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BY THE SAME AUTHOR.

ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION;

or, The Preservation of Favored Races in the Struggle for Life. New
and revised edition, with Additions. i2mo. Cloth, $2.00.

DESCENT OF MAN, AND SELECTION IN RELATION TO

SEX. With many Illustrations. A new edition. i2mo. Cloth, $3.00.

JOURNAL OF RESEARCHES INTO THE NATURAL HISTO-
RY AND GEOLOGY OF THE COUNTRIES VISITED DURING THE
VOYAGE OF H. M. S. BEAGLE ROUND THE WORLD. A new edition.
i2mo. Cloth, $2.00.

EMOTIONAL EXPRESSIONS OF MAN AND THE LOWER

ANIMALS. i2mo. Cloth, $3.50.

THE VARIATIONS OF ANIMALS AND PLANTS UNDER
DOMESTICATION. With a Preface, by Professor Asa Gray. 2 vols. Illus-
trated. Cloth, $5.00.

INSECTIVOROUS PLANTS. i2mo. Cloth, $2.00.
I^IOVEMENTS AND HABITS OF CLIMBING PLANTS. With

Illustrations. i2mo. Cloth, $1.25.

THE VARIOUS CONTRIVANCES BY WHICH ORCHIDS ARE

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THE EFFECTS OF CROSS AND SELF FERTILIZATION IN
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DIFFERENT FORMS OF FLOWERS ON PLANTS OF THE

SAME SPECIES. With Illustrations. i2mo. Cloth, $1.50.

THE POWER OF MOVEMENT IN PLANTS. By Charles Dar-
win, LL. D., F. R. S., assisted by Francis Darwin. With Illustrations. i2mo.
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THE FORMATION OF VEGETABLE MOULD, THROUGH
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trations. 12010. Cloth, $1.50.

For sale by all booksellers ; or sent by mail, post-paid, on receipt of price.

New York: D. APPLETON & CO., 1, 3, & 5 Bond Street.

THE VARIATION

OF

ANIMALS AND PLANTS

UNDER

DOMESTICATION.

By CHAKLES DAEWIN, M.A., F.K.S., &c.

SECOND EDITION, REVISED. FOURTH THOUSAND.

m TWO VOLUMES.— VOL. IL

WITH JLLUSTRATIONS.

NEW YOEK:

D, appleto:n and company,

1, S, AND 5 BOND STREET.

1887.

CONTENTS.

CHAPTER XIII.
INHERITANCE, Continued — reversion or atavism.

DIFFERENT FORMS OF REVERSION — IN PURE OR UNCROSSED BREEDS, AS
IN PIGEONS, FOWLS, HORNLESS CATTLE AND SHEEP, IN CULTIVATED
PLANTS — REVERSION IN FERAL ANIMALS AND PLANTS — REVERSION
IN CROSSED VARIETIES AND SPECIES — REVERSION THROUGH BUD-
PROPAGATION, AND BY SEGMENTS IN THE SAME FLOWER OR FRUIT
— IN DIFFERENT PARTS OF THE BODY IN THE SAME ANIMAL —
THE ACT OF CROSSING A DIRECT CAUSE OF REVERSION, VARIOUS
CASES OF, WITH INSTINCTS —OTHER PROXIMATE CAUSES OF RE-
VERSION — LATENT CHARACTERS — SECONDARY SEXUAL CHARACTERS

— UNEQUAL DEVELOPMENT OF THE TWO SIDES OF THE BODY

APPEARANCE WITH ADVANCING AGE OF CHARACTERS DERIVED
FROM A CROSS — THE GERM, WITH ALL ITS LATENT CHARACTERS,
A WONDERFUL OBJECT — MONSTROSITIES — PELORIC FLOWERS DUE IN

SOME CASES TO REVERSION Pacres 1-36

CHAPTER XIV.
INHERITANCE, continued — fixedness of character —

PREPOTENCY — SEXUAL LIMITATION — CORRESPONDENCE
OF AGE.

iaXEDNT:SS OF CHARACTER APPARENTLY NOT DUE TO ANTIQUITY OF
INHERITANCE — PREPOTENCY OF TRANSMISSION IN INDIVIDUALS OF
THE SAME FAMILY, IN CROSSED BREEDS AND SPECIES ; OFTEN
STRONGER IN ONE SEX THAN THE OTHER; SOMETIMES DUE TO THE
SAME CHARACTER BEING PRESENT AND VISIBLE IN ONE BREED
AND LATENT IN THE OTHER — INHERITANCE AS LIMITED BY SEX

IV CONTENTS.

NEWLT-ACQUTKED CHARACTERS IN OUR DOMESTICATED AISTEMALS
OFTEN TRANSMITTED BY ONE SEX ALONE, SOMETIMES LOST BY ONE

SEX ALONE INHERITANCE AT CORRESPONDING PERIODS OF LIFE

THE IMPORTANCE OF THE PRINCIPLE WITH RESPECT TO EMBRY-
OLOGY ; AS EXHIBITED IN DOMESTICATED ANIMALS ; AS EXHIBITED
IN THE APPEARANCE AND DISAPPEARANCE OF INHERITED DIS-
EASES; SOMETIMES SUPERVENING EARLIER IN THE CHILD THAN
IN THE PARENT — SUMMARY OF THE THREE PRECEDING CHAPTERS.

Pages 37-61

CHAPTEK XV.

ON CROSSING.

FREE INTERCROSSING OBLITERATES THE DIFFERENCES BETWEEN ALLIED
BREEDS — WHEN THE NUMBERS OF TWO COMMINGLING BREEDS ARE
UNEQUAL, ONE ABSORBS THE OTHER — THE RATE OF ABSORPTION
DETERMINED BY PREPOTENCY OF TRANSMISSION, BY THE CON-
DITIONS OF LIFE, AND BY NATURAL SELECTION — ALL ORGANIC
BEINGS OCCASIONALLY INTERCROSS ; APPARENT EXCEPTIONS — ON
CERTAIN CHARACTERS INCAPABLE OF FUSION ; CHIEFLY OR EX-
CLUSIVELY THOSE WHICH HAVE SUDDENLY APPEARED IN THE IN-
DIVIDUAL — ON THE MODIFICATION OF OLD RACES, AND THE
FORMATION OF NEW RACES, BY CROSSING — SOME CROSSED RACES
HAVE BRED TRUE FROM THEIR FIRST PRODUCTION — ON THE CROSS-
ING OF DISTINCT SPECIES IN RELATION TO THE FORMATION OF
DOMESTIC RACES 62-77

CHAPTEK XVI.

CAUSES WHICH INTERFERE WITH THE FREE CROSSING OF
VARIETIES — INFLUENCE OF DOMESTICATION ON FER-
TILITY.

DIFFICULTIES IN JUDGING OF THE FERTILITY OF VARIETIES AVHEN
CROSSED — VARIOUS CAUSES WHICH KEEP VARIETIES DISTINCT, AS
THE PERIOD OF BREEDING AND SEXUAL PREFERENCE — VARIETIES
OF WHEAT SAID TO BE STERILE WHEN CROSSED — VARIETIES OF
MAIZE, VERBASCUM, HOLLYHOCK, GOURDS, MELONS, AND TOBACCO

CONTENTS. V

SEXDEEED IN SOME DEGREE MUTUALLY STERILE — DOMESTICATION
ELIMINATES THE TENDENCY TO STERILITY NATURAL TO SPECIES
WHEN CROSSED — ON THE INCREASED FERTILITY OF UNCROSSED
ANIMALS AND PLANTS FROM DOMESTICATION AND CULTIVATION.

Pages 78-91

CHAPTER XVII.

ON THE GOOD EFFECTS OF CHOSSING, AND ON THE EVIL
EFFECTS OF CLOSE INTERBREEDING.

DEFINITION OF CLOSE INTERBREEDING — AUGMENTATION OF MORBID

TENDENCIES C ENTERAL EVIDENCE OF THE GOOD EFFECTS DERIVED

FROM CROSSING, AND ON THE EVIL EFFECTS OF CLOSE INTERBREED-
ING — CATTLE, CLOSELY INTERBRED ; HALF-WILD CATTLE LONG
KEPT IN THE SAME PARKS — SHEEP — FALLOW-DEER — DOGS, RABBITS,
PIGS — MAN, ORIGIN OF HIS ABHORRENCE OF INCESTUOUS MARRIAGES
— FOWLS PIGEONS — HIVE-BEES PLANTS, GENERAL CONSIDERA-
TIONS ON THE BENEFITS DERIVED FROM CROSSING — MELONS, FRUIT-
TREES, PEAS, CABBAGES, WHEAT, AND FOREST-TREES — ON THE
INCREASED SIZE OF HYBRID PLANTS, NOT EXCLUSIVELY DUE TO
THEIR STERILITY — ON CERTAIN PLANTS WHICH EITHER NORMALLY
OR ABNORMALLY ARE SELF-IMPOTENT, BUT ARE FERTILE BOTH
ON THE MALE AND FEMALE SIDE, WHEN CROSSED WITH DISTINCT
INDIVIDUALS EITHER OF THE SAME OR ANOTHER SPECIES — CON-
CLUSION 92-126

CHAPTER XVIII.

ON THE ADVANTAGES AND DISADVANTAGES OF CHANGED
CONDITIONS OF LIFE : STERILITY FROM VARIOUS CAUSES.

ON THE GOOD DERIVED FROM SLIGHT CHANGES IN THE CONDITIONS OF
LIFE— STERILITY FROM CHANGED CONDITIONS, IN ANIMALS, IN
THEIR NATIVE COUNTRY AND IN MENAGERIES — MAMMALS, BIRDS,
AND INSECTS — LOSS OF SECONDARY SEXUAL CHARACTERS AND OF
INSTINCTS — CAUSES OF STERILITY — STERILITY OF DOMESTICATED
ANIMALS FROM CHANGED CONDITIONS — SEXUAL INCOMPATIBILITY
OF INDIVIDUAL ANIMALS — STERILITY OF PLANTS FROM CHANGED

VI CONTENTS.

CONDITIONS OF LIFE — CONTABESCENCE OF THE ANTHERS — MON-
STROSITIES AS A CAUSE OF STERILITY — DOUBLE FLOWERS— SEED-
LESS FRUIT — STERILITY FROM THE EXCESSIVE DEVELOPMENT OF
THE ORGANS OF VEGETATION — FROM LONG-CONTINUED PROPAGA-
TION BY BUDS — INCIPIENT STERILITY THE PRIMARY CAUSE OF
DOUBLE FLOWERS AND SEEDLESS FRUIT ,. .. Pages 127-156

CHAPTER XIX.

SUMMARY OF TFIE FOUR LAST CHAPTERS, WITH REMARKS

ON HYBRIDISM.

ON THE EFFECTS OF CROSSING THE INFLUENCE OF DOMESTICATION

ON FERTILITY — CLOSE INTERBREEDING — GOOD AND EVIL RESULTS
FROM CHANGED CONDITIONS OF LIFE — VARIETIES WHEN CROSSED
NOT INVARIABLY FERTILE ON THE DIFFERENCE IN FERTILITY BE-
TWEEN CROSSED SPECIES AND VARIETIES — CONCLUSIONS WITH RE-
SPECT TO HYBRIDISM — LIGHT THROWN ON HYBRIDISM BY THE

ILLEGITIMATE PROGENY OF HETEROSTYLED PLANTS STERILITY

OF CROSSED SPECIES DUE TO DIFFERENCES CONFINED TO THE
REPRODUCTIVE SYSTEM — NOT ACCUMULATED THROUGH NATURAL

SELECTION REASONS WHY DOMESTIC VARIETIES ARE NOT MUTUALLY

STERILE — TOO MUCH STRESS HAS BEEN LAID ON THE DIFFERENCE
IN FERTILITY BETWEEN CROSSED SPECIES AND CROSSED VARIETIES
— CONCLUSION 157-175

CHAPTER XX.

SELECTION BY MAN.

SELECTION A DIFFICULT ART — METHODICAL, UNCONSCIOUS, AND NATURAL
SELECTION — RESULTS OF METHODICAL SELECTION — CARE TAKEN IN
SELECTION — SELECTION WITH PLANTS — SELECTION CARRIED ON BY
THE ANCIENTS AND BY SEMI-CIVILISED PEOPLE — UNIMPORTANT

CHARACTERS OFTEN ATTENDED TO — UNCONSCIOUS SELECTION AS

CIRCUMSTANCES SLOWLY CHANGE, SO HAVE OUR DOMESTICATED
ANIMALS CHANGED THROUGH THE ACTION OF UNCONSCIOUS SELEC-
TlOJSr — INFLUENCE OF DIFFERENT BREEDERS ON THE SAME SUB-

CONTENTS. Vll

VARIETY — PLANTS AS AFFECTED BY U^X'ONSCIOUS SELECTION

EFFECTS OF SELECTION AS SHOWN BY THE GREAT AMOUNT OP
DIFFERENCE IN THE PARTS MOST VALUED BY MAN .. PageS 176-208

CHAPTER XXL

SELECTION, continued.

NATURAL SELECTION AS AFFECTING DOMESTIC PRODUCTIONS — CHARAC-
TERS WHICH APPEAR OF TRIFLING VALUE OFTEN OF REAL IM-
PORTANCE — CIRCUMSTANCES FAVOURABLE TO SELECTION BY MAN

FACILITY IN PREVENTING CROSSES, AND THE NATURE OF THE
CONDITIONS — CLOSE ATTENTION AND PERSEVERANCE INDISPENSABLE
THE PRODUCTION OF A LARGE NUMBER OF INDIVIDUALS ESPE-
CIALLY FAVOURABLE — WHEN NO SELECTION IS APPLIED, DISTINCT
RACES ARE NOT FORMED — HIGHLY-BRED ANIMALS LIABLE TO DE-
GENERATION — TENDENCY IN MAN TO CARRY THE SELECTION OF
EACH CHARACTER TO AN EXTREME POINT, LEADING TO DIVERGENCE
OF CHARACTER, RARELY TO CONVERGENCE — CHARACTERS CON-
TINUING TO VARY IN THE SAME DIRECTION IN WHICH THEY HAVE
ALREADY VARIED — DIVERGENCE OF CHARACTER WITH THE EX-
TINCTION OF INTERMEDIATE VARIETIES, LEADS TO DISTINCTNESS IN
OUR DOMESTIC RACES— LIMIT TO THE POWER OF SELECTION — LAPSE
OF TIME IMPORTANT — MANNER IN WHICH DOMESTIC RACES HAVE
ORIGINATED — SUMMARY 209-236

CHAPTER XXII.

CAUSES OF VARIABILITY.

t? A.RIABILITY DOES NOT NECESSARILY ACCOMPANY REPRODUCTION

CAUSES ASSIGNED BY VARIOUS AUTHORS — INDIVIDUAL DIFFERENCES

VARIABILITY OF EVERY KIND DUE TO CHANGED CONDITIONS OF

LIFE— ON THE NATURE OF SUCH CHANGES — CLIMATE, FOOD, EX-
CESS OF NUTRIMENT — SLIGHT CHANGES SUFFICIENT — EFFECTS OF
GRAFTING ON THE VARIABILITY OF SEEDLING-TREES — DOMESTIC PRO-
DUCTIONS BECOME HABITUATED TO CHANGED CONDITIONS — ON THE
ACCUMULATIVE ACTION OF CHANGED CONDITIONS — CLOSE INTER-
BREEDING AND THE IMAGINATION OF THE MOTHER SUPPOSED TO

Vm CONTENTS.

CAUSE VAEIABILITT — CIIOSSING AS A CAUSE OF THE APPEARANCE
OF NEW CHARACTERS — VARIABILITY FROM THE COMMINGLING OF
CHARACTERS AND FROM REVERSION — ON THE MANNER AND PERIOD
OF ACTION OF THE CAUSES WHICH EITHER DIRECTLY, OR IN-
DIRECTLY THROUGH THE REPRODUCTIVE SYSTEM, INDUCE VARIA-
BILITY Pasjes 237-259

CHAPTEE XXIII.

DIRECT AND DEFINITE ACTION OF THE EXTERNAL CON-

DITIO^"S OF LIFE.

SLIGHT MODIFICATIONS IN PLANTS FROM THE DEFINITE ACTION OF
CHANGED CONDITIONS, IN SIZE, COLOUR, CHEMICAL PROPERTIES,
AND IN THE STATE OF THE TISSUES — LOCAL DISEASES — CON-
SPICUOUS MODIFICATIONS FROM CHANGED CLIMATE OR FOOD, ETC.

PLUMAGE OF BIRDS AFFECTED BY PECULIAR NUTRIMENT, AND

BY THE INOCULATION OF POISON — LAND-SHELLS — MODIFICATIONS OF
ORGANIC BEINGS IN A STATE OF NATURE THROUGH THE DEFINITE
ACTION OF EXTERNAL CONDITIONS — COMPARISON OF AMERICAN
AND EUROPEAN TREES — GALLS — EFFECTS OF PARASITIC FUNGI —
CONSIDERATIONS OPPOSED TO THE BELIEF IN THE POTENT IN-
FLUENCE OF CHANGED EXTERNAL CONDITIONS — PARALLEL SERIES
OF VARIETIES — AMOUNT OF VARIATION DOES NOT CORRESPOND
WITH THE DEGREE OF CHANGE IN THE CONDITIONS — BUD-VARIA-
TION MONSTROSITIES PRODUCED BY UNNATURAL TREATMENT

SUMMARY 260-282

CHAPTER XXIV.

LAWS OF VARIATION — USE AND DISUSE, ETC.

KISUS FORMATIVUS, OR THE CO-ORDINATING POWER OF THE ORGANISA-
TION — ON THE EFFECTS OF THE INCREASED USE AND DISUSE OF

ORGANS CHANGED HABITS OF LIFE ACCLIMATISATION WITH

ANIMALS AND PLANTS — VARIOUS METHODS BY WHICH THIS CAN
BE EFFECTED — ARRESTS OF DEVELOPMENT— RUDIMENTARY ORGANS.

283-310

CONTENTS. IX

CHAPTER XXV.

LAWS OF VARIATION, continued— COnUELATEl> VARIA-
BILITY.

EXPLANATION OF TERM CORRELATION — CONNECTED WITH DEVELOP-
MENT — MODIFICATIONS CORRELATED WITH THE INCREASED OR
DECREASED SIZE OF PARTS — CORRELATED VARIATION OF HOMO-
LOGOUS PARTS — FEATHERED FEET IN BIRDS ASSUMING THE STRUC-
TURE OF THE WINGS — CORRELATION BETWEEN THE HEAD AND
THE EXTREMITIES — BETWEEN THE SKIN AND DERMAL APPENDAGES
— BETWEEN THE ORGANS OF SIGHT AND HEARING — CORRELATED
MODIFICATIONS IN THE ORGANS OF PLANTS — CORRELATED MON-
STROSITIES — CORRELATION BETWEEN THE SKULL AND EARS — SKULL
AND CREST OF FEATHERS — SKULL AND HORNS — CORRELATION OF
(iROWTH COMPLICATED BY THE ACCUMULATED EFFECTS OF NATURAL
SELECTION — COLOUR AS CORRELATED WITH CONSTITUTIO^TAL PECU-
LIARITIES Pa^es 31 1-3S2

CHAPTER XXVI.

LAWS OF VARIATION, continued — summary.

THE FUSION OF HOMOLOGOUS PARTS — THE VARIABILITY OF MULTIPLE
AND HOMOLOGOUS PARTS — COMPENSATION OF GROWTH — MECHANICAL
PRESSURE— RELATIVE POSITION OF FLOWERS WITH RESPECT TO
THE AXIS, AND OF SEEDS IN THE OVARY, AS INDUCING VARIA-
TION ANALOGOUS OR PARALLEL VARIETIES — SUMMARY OF THE

THREE LAST CHAPTERS 333-348

CHAPTER XXVII.

PROVISIONAL HYPOTHESIS OF PANGENESIS.

PRELIMINARY REMARKS — FIRST PART:— THE FACTS TO BE CONNECTED
UNDER A SINGLE POINT OF VIEW, NAMELY, THE VARIOUS KINDS
OF REPRODUCTION — RE-GROWTH OF AMPUTATED PARTS — GRAFT-
HYBRIDS — THE DIRECT ACTION OF THE MALE ELEMENT ON THE

X CONTENTS.

FEMALE — DEVELOPMENT — THE FUNCTIONAL INDEPENDENCE OF THE
UNITS OF THE BODY — VARIABILITY — INHERITANCE — REVERSION.

SECOND PART : STATEMENT OF THE HYPOTHESIS HOW FAR THE

NECESSARY ASSUMPTIONS ARE IMPROBABLE — EXPLANATION BY AID
OF THE HYPOTHESIS OF THE SEVERAL CLASSES OF FACTS SPECI-
FIED IN THE FIRST PART — CONCLUSION .. .. Pagt'S 349-399

CHAPTEE XXVIII.

CONCLUDING EEMARKS.

DOMESTICATION — NATURE AND CAUSES OF VARIABILITY — SELECTION —

DIVERGENCE AND DISTINCTNESS OF CHARACTER EXTINCTION OF

RACES — CIRCUMSTANCES FAVOURABLE TO SELECTION BY MAN —
ANTIQUITY OF CERTAIN RACES — THE QUESTION WHETHER EACH
PARTICULAR VARIATION HAS BEEN SPECIALLY PREORDAINED.

400-428

INDEX 429

THE

VARIATION OF ANIMALS AND PLANTS

UNDER DOMESTICATION.

CHAPTER XIII.

INHERITANCE continued — REVERSION OR ATAVISM.

DIFFERENT FORMS OF REVERSION — IN PURE OR UNCROSSED BREEDS, AS IN
PIGEONS, FOWLS, HORNLESS CATTLE AND SHEEP, IN CULTIVATED PLANTS

REVERSION IN FERAL ANIMALS AND PLANTS — REVERSION IN CROSSED

VARIETIES AND SPECIES — REVERSION THROUGH BUD-PROPAGATION, AND
BY SEGMENTS IN THE SAME FLOWER OR FRUIT — IN DIFFERENT PARTS
OF THE BODY IN THE SAME ANIMAL — THE ACT OF CROSSING A DIRECT
CAUSE OF REVERSION, VARIOUS CASES OF, WITH INSTINCTS — OTHER

PROXIMATE CAUSES OF REVERSION LATENT CHARACTERS SECONDARY

SEXUAL CHARACTERS — UNEQUAL DEVELOPMENT OF THE TWO SIDES OF
THE BODY — APPEARANCE WITH ADVANCING AGE OF CHARACTERS DERIVED
FROM A CROSS — THE GERM, WITH ALL ITS LATENT CHARACTERS, A
WONDERFUL OBJECT — MONSTROSITIES — PELORIC FLOWERS DUE IN SOME
CASES TO REVERSION.

The great principle of inlieritance to be discussed in this
chapter has been recognised by agriculturists and authors of
various nations, as shown by the scientific term Atavism, de-
rived from atavus, an ancestor; by the English terms of
Meversion, or Throidng-hach ; by the French Pas-en-Arriere ;
and by the German MiXckschlag, or Muckschritt. When the
child resembles either grandparent more closely than its
immediate parents, our attention is not much arrested, though
in truth the fact is highly remarkable ; but when the child
resembles some remote ancestor or some distant member in a
collateral line, — and in the last case we must attribute this to
the descent of all the members from a common progenitor, —
we feel a just degree of astonishment. When one parent
alone displays some newly-acquired and generally inheritable

2 INHERITANCE. Chap. XIII.

character, and tlie offspring do not inherit it, the cause may
lie in the other parent having the power of prepotent trans-
mission. But when both parents are similarly characterised,
and the child does not, whatever the canse may be, inherit
the character in question, but resembles its grandparents, we
have one of the simplest cases of reversion. We continually
se6 another and even more simple case of atavism, though
not generally included under this head, namely, when the son
more closely resembles his maternal than his paternal grand-
sire in some male attribute, as in any peculiarity in the beard
of man, the horns of the bull, the hackles or comb of the cock,
or, as in certain diseases necessarily confined to the male sex ;
for as the mother cannot possess or exhibit such male attri-
butes, the child must inherit them, through her blood, from
his maternal grandsire.

The cases of reversion ma^^ be divided into two main classes
which, however, in some instances, blend into one another ;
namely, first, those occurring in a variety or race which has
not been crossed, but has lost by variation some character
that it formerly possessed, and which afterwards reappears.
The second class includes all cases in which an individual
with some distinguishable character, a race, or species, has at
some former period been crossed, and a character derived from
this cross, after having disappeared during one or several
generations, suddenly reappears. A third class, differing only
in the manner of reproduction, might be formed to include
all cases of reversion effected by means of buds, and therefore
independent of true or seminal generation. Perhaps even a
fourth class might be instituted, to include reversions by seg-
ments in the same individual flower or fruit, and in different
parts of the body in the same individual animal as it grows
old. But the two first main classes will be sufficient for our
purpose.

Heversion to lost Characters hy jmre or uncrossed forms. —
Striking instances of this first class of cases were given in
the sixth chapter, namely, of the occasional reappearance, in
variously-coloured breeds of the pigeon, of blue birds with all
the marks characteristic of the wild Columha livia. Similar

Chap. XIII. REVERSION. 3

cases were given in the case of tlie fowl. AVith the common
ass, as the legs of the wild progenitor are almost always
striped, we may feel assured that the occasional ajDpearance
of such stripes in the domestic animal is a case of simple
reversion. But I shall be compelled to refer again to these
cases, and therefore here pass them over.

The aboriginal species from which our domesticated cattle
and sheep are descended, no doubt possessed horns ; but
several hornless breeds are now well established. Yet in
these — for instance, in Southdown sheep — " it is not unusual
to find among the male lambs some with small horns," The
horns, which thus occasionally reappear in other polled breeds,
either " grow to the full size," or are curiously attached to the
skin alone and hang "loosely down, or drop oftV'^ The
Galloways and Suifolk cattle have been hornless for the last
100 or 150 years, but a horned calf, with the horn often
loosely attached, is occasionally produced. ^

There is reason to believe that sheep in their early domesti-
cated condition were " brown or dingy black ; " but even in
the time of David certain flocks were spoken of as white as
snow. During the classical period the sheep of Spain are
described by several ancient authors as being black, red, or
tawny. ^ At the present day, notwithstanding the great care
which is taken to prevent it, particoloured lambs and some
entirely black are occasionally, or even frequently, dropped
by our most highly improved and valued breeds, such as the
Southdowns. Since the time of the famous Bakewell, daring
the last century, the Leicester sheep have been bred with the
most scrupulous care ; yet occasionally grey-faced, or black-
spotted, or wholly black lambs appear."* This occurs still
more frequently with the less improved breeds, such as the
Norfolks.^ As bearing on this tendency in sheep to revert
to dark colours, I may state (though in doing so I trench on

* Youatt on Sheep, pp. 20, 234. 145.

The same fact of loose horns oc- * I have been informed of this fact

casionally appearing in hornless breeds through the Rev. W. D. Fox, on the

bas been observed in Germany ; excellent authority of Mr. Wilmot :

Bechstein, ' Naturgesch. Deutsch- see, also, remarks on this subject in

Lnds.' b. i. s. 362. an article in the 'Quarterly Review,'

2 Youatt on Cattle, pp. 155, 174. 1849, p. 395.

* Youatt on Sheep, 1838, pp. 17, ^ Youatt, pp. 19, 234.

4 INHEKITANCE. Chap. XIII.

the reversion of crossed breeds, and likewise on the subject of
prepotency) that the Eev. W. D. Fox was informed that seven
white Southdown ewes were put to a so-called Spanish ram,
which had two small black spots on his sides, and they pro-
duced thirteen lambs, all perfectly black. Mr. Fox believes
that this ram belonged to a breed which he has himself kept,
and which is always spotted with black and white ; and he
finds that Leicester sheep crossed by rams of this breed always
produce black lambs : he has gone on recrossing these crossed
sheep with pure white Leicesters during three successive
generations, but always with the same result. ]\Ir. Fox was
also told by the friend from whom the sjDotted breed was
procured, that he likewise had gone on for six or seven gene-
rations crossing with white sheep, but still black lambs were
invariably produced.

Similar facts could be given with respect to tailless breeeds
of various animals. For instance, Mr. Hewitt ^ states that
chickens bred from some rumpless fowls, which were reckoned
so good that they won a prize at an exhibition, " in a consider-
able number of instances were furnished with fully developed
tail-feathers." On inquiry, the original breeder of these fowls
stated that, from the time when he had first kept them, they
had often produced fowls furnished with tails ; but that these
latter would again reproduce rumpless chickens.

Analogous cases of reversion occur in the vegetable king-
dom ; thus " from seeds gathered from the finest cultivated
varieties of Heartsease (^Viola tricolor), plants perfectly wild
both in their foliage and their flowers are frequently pro-
duced ;" "^ but the reversion in this instance is not to a very
ancient period, for the best existing varieties of the heartsease
are of comparatively modern origin. With most of our cul-
tivated vegetables there is some tendency to reversion to
what is known to be, or may be presumed to be, their abori-
ginal state ; and this would be more evident if gardeners did
not generally look over their beds of seedlings, and pull up

® ' The Poultry Book,' by Mr. much experience on this subject, has

Tegetmeier, 1866, p. 231. likewise assured me that this some-

^ Loudon's ' Gard. Mag.,' vol. x., times occurs.
1834, p. 396 : a nurseryman, with

Chap. XIII. EEVEESION. 5

the false plants or " rogues " as they are called. It has
already been reioarked, that some few seedling apples and
pears generally resemble, but apparently are not identical
with, the wild trees from which they are descended. In our
turnip ^ and carrot-beds a few plants often " break " — that is,
flower too soon ; and their roots are generally hard and
stringy, as in the parent-species. By the aid of a little
selection, carried on during a few generations, most of our
cultivated plants could probably be brought back, without
any great change in their conditions of life, to a wild or
nearly wild condition : Mr. Buckman has effected this with
the parsnip ; ^ and Mr. Hewett C. Watson, as he informs me,
selected, during three generations, " the most diverging
plants of Scotch kail, perhaps one of the least modified
varieties of the cabbage ; and in the third generation some
of the plants came very close to the forms now established in
England about old castle-walls, and called indigenous."

Reversion in Animals and Plants icMch have run wild. — In
the cases hitherto considered, the reverting animals and
plants have not been exposed to any great or abrupt change
in their conditions of life which could have induced this
tendency ; but it is very different with animals and plants
which have become feral or run wild. It has been repeatedly
asserted in the most positive manner by various authors, that
feral animals and plants invariably return to their primitive
specific type. It is curious on what little evidence this belief
rests. ]\Iany of our domesticated animals could not subsist
in a wild state ; thus, the more highly improved breeds of
the pigeon will not " field " or search for their own food.
Sheep have never become feral, and would be destroyed by
almost every beast of prey.^° In several cases we do not
know the aboriginal parent-species, and cannot possibly tell

* 'Gardener's Chron.,' 1855, p. foxind that they are not able to es-

777. tablish themselves; they generally

® Ibid., 1862, p. 721. perish from the frozen snow clingina

^^ Mr. Boner speaks (' Chamois- to their wool, and they have lost the

hunting,' 2nd edit,, 1860, p. 92) of skill necessary to pass over steep icy

sheep often rvinning wild in the slopes. On one occasion two ewe's

Bavarian Alps ; but, on making survived the winter, but their lambs

forther inquiries at my request, he perished.

6 INHERITANCE. Chap. XIII.

vvhetlier or not there has been any close degree of reversion.
It is not known in any instance what variety was first turned
out ; several varieties have probably in some cases run wild,
and their crossing alone would tend to obliterate their proper
character. Our domesticated animals and plants, when they
run wild, must alwaj^s be exposed to new conditions of life,
for, as Mr. Wallace ^^ has well remarked, they have to obtain
their own food, and are exposed to competition with the native
productions. Under these circumstances, if our domesticated
animals did not undergo change of some kind, the result
would be quite opposed to the conclusions arrived at in this
work. Nevertheless, I do not doubt that the simple fact
of animals and plants becoming feral, does cause some
tendency to reversion to the primitive state ; though this
tendency has been much exaggerated by some authors.

I will briefly run tlu'ougli the recorded cases. With neither
horses nor cattle is the priinitive stock known; and it has been
shown in former chapters that they have assumed diiferent colours
in diifereut countries. Thus the horses which have run wild in
South America are generally brownish-bay, and in the East dun-
coloured ; their heads have become larger and coarser, and this
may be due to reversion. No careful description has been given of
the feral goat. Dogs which have run wild in various countries
have hardly anywhere assumed a uniform character; but, they are
probably descended from several domestic races, and aboriginally
from several distinct species. Feral cats, both in Europe and
La Plata, are regularly striped ; in some cases they have grown to
an unvisually large size, but do not differ from the domestic animal
in any other character. When variously-coloured tame rabbits
are turned out in Europe, they generally reacquire the colouring of
the wild animal ; there can be no doubt that this does really occur,
but we should remember that oddly-coloured and conspicuous
animals would suffer much from beasts of prey and from being
easily shot ; this at least was the opinion of a gentleman who tried
to stock his woods with a nearly white variety ; if thus destroyed,
they would be supplanted by, instead of being transformed into,
the common rabbit. We have seen that the feral rabbits of Jamaica,
and especially of Porto Santo, have assumed new colours and other
new characters. The best known case of reversion, and that on
which the widely spread belief in its universality apparently rests,
is that of pigs. These animals have run wild in tlie West Indies,
South America, and the Falkland Islands, and have everywhere

*• See some excellent remarks on Proc, Linn. Soc.,' 1858, vol. iii. p. 60,
this subject by Mr. Wallace, ' Journal

Chap. XIH.

BE VERSION.

acquired the dark colour, the thick bristles, and great tusks of the
wild boar; and the young have reacquired longitudinal stripes.
But even in the case of the pig, Eoulin describes the half-wild
animals in diflferent parts of South America as differing in several
respects. In Louisiana the pig^^ has run wild, and is said to differ
a little in form, and much in colour, from the domestic animal, yet
does not closely resemble the wild boar of Europe. "With pigeons
and fowls,^^ it is not known what variety was first turned out, nor
Avhat character the feral birds have assumed. The guinea-fowl in
the West Indies, when feral, seems to vary more than in the
domesticated state.

With respect to plants run wild. Dr. Hooker" has strongly
insisted on what slight evidence the common belief in their
reversion to a primitive state rests. Godron^^ describes wild
turnips, carrots, and celery; but these plants in their cultivated
state hardly differ from their wild prototypes, except in the succu-
lency and enlargement of certain parts, — characters which would
certainly be lost by plants growing in poor soil and struggling with
other plants. No cultivated plant has run wild on so enormous
a scale as the cardoon {Cynara cardunculus) in La Plata. Every
botanist who has seen it growing there, in vast beds, as high as
a horse's back, has been struck with its peculiar appearance ; but
whether it differs in any important point from the cultivated
Spanish form, which is said not to be prickly like its American
descendant, or whether it differs from the wild Mediterranean
species, which is said not to be social (though this may be due
merely to the nature of the conditions), I do not know.

Heversion to Characters derived from a Cross, in the case of
Sub -varieties. Races, and Species. — When an individual having
some recognisable peculiarity unites with another of the same
sub-variety, not having the peculiarity in question, it often
reappears in the descendants after an interval of several gene-
rations. Every one must have noticed, or heard from old
people of children closely resembling in appearance or mental
disposition, or in so small and complex a character as expres-

^- Bureau de la Malle, in ' Comptes
Rendus,' torn, xli., 18"'5, p. 807.
From the statements above given, the
author concludes that the wild pigs
of Louisiana are not descended from
the European Sus scrofa.

** Capt. W. Allen, in his * Expe-
dition, to the Niger,' states that fowls
have run wild on the island of Anno-
bon, and have become modified in
form and voice. The account is so
meacrre and vague that it did not

appear to me worth copying; but I now
find that Dureau de la Mallet^' Comp-
tes Rendus,' tom. xli., 1855, p. 690)
advances this as a good instance of
reversion to the primitive stock, and as
confirmatory of a still more v;igue
statement in classical times by Yarro.

1* 'Flora of Australia,' 1859, In-
troduct., p. ix.

^^ ' De I'Espece,' tom. ii. pp. 54,
58, 60.

8 INHERITANCE. OiiAP. XIII.

sion,' one of their grandparents, or some more distant collateral
relation. Very many anomalies of structure and diseases,^®
of wliich instances have been given in the last chapter, have
come into a family from one parent, and have reappeared
in the progeny after passing over two or three generations.
The following case has been communicated to me on good
authority, and may, I believe, be fully trusted : a pointer-bitch
produced seven puppies ; four were marked with blue and
white, which is so unusual a colour with pointers that she was
thought to have played false with one of the greyhounds, and
the whole litter was condemned ; but the gamekeeper was per-
mitted to save one as a curiosity. Two years afterwards a
friend of the owner saw the young dog, and declared that he
was the image of his old pointer-bitch Sappho, the only blue
and white pointer of pure descent which he had ever seen.
This led to close inquiry, and it was proved that he was the
great-great-grandson of Sappho ; so that, according to the
common expression, he had only 1-1 6th of her blood in his
veins. I may give one other instance, on the authority of
Mr. E. Walker, a large cattle-breeder in Kincardineshire.
He bought a black bull, the son of a black cow with white
legs, white belly and part of the tail white; and in 1870
a calf the gr.-gr.-gr.-gr.-grandchild of this cow was born
coloured in the same veiy peculiar manner ; all the inter-
mediate offspring having been black. In these cases there
can hardly be a doubt that a character derived from a cross
with an individual of the same variety reappeared after
passing over three generations in the one case, and five in the
other.

When two distinct races are crossed, it is notorious that the
tendency in the offspring to revert to one or both parent-
forms is strong, and endures for many generations. I have
myself seen the clearest evidence of this in crossed pigeons
and with various j^lants. Mr. Sidney ^' states that, in a litter
of Essex pigs, two young ones appeared which were the image
of the Berkshire boar that had been used twenty-eight years

" Mr. Sedgwick gives many in- July, 1863, pp. 448, 188.
stances in The ' British and Foreign *' In his edit, of ' Youatt on the

Med-Chirurg. Review,' April and Pig,' 1860, p. 27.

Chap. XIII. REVEKSION. 9

before in giving size and constitution to the breed. I ob-
eerved in the farmyard at Betley Hall some fowls showing a
strong likeness to the Malay breed, and was told by Mr.
Toilet that he had forty years before crossed his birds with
Malays; and that, though he had at first attempted to get
rid of this strain, he had subsequently given up the attempt
in despair, as the Malay character would reappear.

This strong tendency in crossed breeds to revert has given
]-ise to endless discussions in how many generations after a
single cross, either with a distinct breed or merely with an
inferior animal, the breed may be considered as pure, and free
from all danger of reversion. Ko one supposes that less than
three generations suffices, and most breeders think that six,
seven, or eight are necessary, and some go to still greater
leno-ths.^^ But neither in the case of a breed which has been
contaminated by a single cross, nor w^hen, in the attempt to
form an intermediate breed, half-bred animals have been
matched together during many generations, can any rule be
laid down how soon the tendency to reversion will be oblitera-
ted. It depends on the difference in the strength or pre-
potency of transmission in the two parent-forms, on their
actual amount of difference, and on the nature of the con-
ditions of life to which the crossed offspring are exposed. But
we must be careful not to confound these cases of reversion to
characters which were gained by a cross, with those under the
first class, in which characters originally common to both
parents, but lost at some former period, reappear ; for such
characters may recur after an almost indefinite number of
generations.

The law of reversion is as powerful with hybrids, when
they are sufficiently fertile to breed together, or when they
are repeatedly crossed with either pure j)arent-form, as in the
case of mongrels. It is not necessary to give instances.
With plants almost every one who has worked on this sub-
ject, from the time of Kolreuter to the present day, has
insisted on this tendency. Gartner has recorded some good
instances; but no one has given more striking ones than

'8 Dr. P. Lucas, ' Hered. Nat.,' * Gard. Chronicle,' 1856, p. 620. 1
torn. ii. pp. 314, 892: see a good could add a vast number of references,
practical article on the subject in but th^y would be superfluous.

10

INHERITANCE.

Chap. XII [.

Naiidin.^^ The tendency dififers in degree or strength in
different groups, and partly depends, as we shall presently
see, on whether the parent-plants have been long cultivated.
Although the tendency to reversion is extremely general
with nearly all mongrels and hybrids, it cannot be considered
as invariably characteristic of them ; it may also be mastered
by long-continued selection ; but these subjects will more
properly be discussed in a future chapter on Crossing. From
what we see of the power and scope of reversion, both in pure
races, and when varieties or species are crossed, we may infer
that characters of almost every kind are capable of reappear-
ing after having been lost for a great length of time. But it
does not follow from this that in each particular case certain
characters will reappear ; for instance, this will not occur
when a race is crossed with another endowed with prepotency
of transmission. Sometimes the power of reversion wholly
fails, without our being able to assign any cause for the
failure : thus it has been stated that in a French family in
which 85 out of above 600 members, during six generations,
had been subject to night-blindness, " there has not been a
single example of this affection in the children of parents who
were themselves free from it."'-°

Heversion through Bud-propagation — Partial Iteversio7i, hy seg-
ments in the same floicer or fruit, or in different parts of the body
in the same individual animal. — In the eleventh chapter many
cases of reversion by buds, independently of seminal genera-
tion, were given — as when a leaf-bud on a variegated, a
curled, or laciniated variety suddenly reassumes its proper
character ; or as when a Provence-rose appears on a moss-rose,
or a peach on a nectarine-tree. In some of these cases only
half the flower or fruit, or a smaller segment, or mere stripes,
reassume their former character ; and here we have reversion

^^ Kolreuter gives curious cases in
his ' Dritte Fortsetzung,' 1766, ss. 53,
59; and in his well-known 'Memoirs
on Lavatera and Jalapa.' Gartner,
* Bastarderzevigung,' ss. 437, 441, &c.
Naudin, in his " Recherches sur
I'Hybridite," ' Nouvelles Archives du
Museum,' tom. i. p. 25.

^'^ Quoted by Mr. Sedgwick in

' Med.-Chirurg. Review,' April, 1861,
p. 485. Dr. H. Dobell, in 'Med.-
Chirurg. Transactions,' vol. xlvi.,
gives an analogous case, in which, in
a large family, fingers with thickened
joints were transmitted to several
members during five generations ;
but when the blemish once disappeared
it never reappeared.

Chap. XIII. KEVERSION. 11

by segments. Yilmoriu^^ has also recorded several cases with
plants derived from seed, of flowers reverting by stripes or
blotches to their primitive colours : he states that in all such
cases a white or pale-coloured variety must first be formed,
and, when this is propagated for a length of time by seed,
striped seedlings occasionally make their appearance ; and
these can afterwards by care be multiplied by seed.

The stripes and segments just referred to are not due, as far
as is known, to reversion to characters derived from a cross,
but to characters lost by variation. These cases, however, as
Naudin^^ insists in his discussion on disjunction of character,
are closely analogous wdth those given in the eleventh chapter,
in which crossed plants have been known to produce half-
and-half or striped flow^ers and fruit, or distinct kinds of
flow^ers on the same root resembling the two parent-forms.
Many piebald animals probably come under this same head.
Such cases, as we shall see in the chapter on Crossing, appa-
rently result from certain characters not readily blending
together, and, as a consequence of this incapacity for fusion,
the offspring either perfectly resemble one of their two
parents, or resemble one parent in one part, and the other
parent in another part ; or whilst young are intermediate in
character, but wdth advancing age revert w^holly or by seg-
ments to either parent-form, or to both. Thus, young trees
of the Cytisus adami are intermediate in foliage and flowers
between the two parent-forms ; but when older the buds
continually revert either partially or wholly to both forms.
The cases given in the eleventh chapter on the changes which
occurred during growth in crossed plants of TropEeolum, Cereus,
Datura, and Lathyrus are all analogous. As, however, these
plants are hybrids of the first generation, and as their buds
after a time come to resemble their parents and not their
grandparents, these cases do not at first appear to come under
the law of reversion in the ordinary sense of the w^ord ; never-
theless, as the change is effected through a successiun of bud-
generations on the same plant, they may be thus included.

Analogous facts have been observed in the animal kingdom,

21 Verlot, 'Des Varietes,' 1865, torn. i. p. 25. Alex. Braun (in his 'Ke-
p. 63. juvenescence,' Ray Soc, 1853, p. 315)

" 'Nouvelles Archives du Museum,' apparently holds a similar opinion.

12 INHERITANCE. Chap. XIII.

and are more remarkable, as they occur in the same individual
in the strictest sense, and not as with plants through a suc-
cession of bud-generations. With animals the act of rever-
sion, if it can be so designated, does not pass over a true
generation, but merely over the early stages of growth in the
same individual. For instance, I crossed several white hens
with a black cock, and many of the chickens were, during the
first year, perfectly white, but acquired during the second year
black feathers ; on the other hand, some of the chickens
which were at first black, became during the second year
piebald with white. A great breeder ^^ says, that a Pencilled
Brahma hen which has any of the blood of the Light Brahma
in her, will "occasionally produce a pullet well pencilled
during the first year, but she will most likely moult brown on
the shoulders and become quite unlike her original colours in
the second year." The same thing occurs with light Brahmas
if of impure blood. I have observed exactly similar cases
with the crossed ofispring from differently coloured pigeons.
But here is a more remarkable fact : I crossed a turbit, which
has a frill formed by the feathers being reversed on its breast,
with a trumpeter ; and one of the young pigeons thus raised
at first showed not a trace of the frill, but, after moulting
thrice, a small yet unmistakably distinct frill appeared on
its breast. According to Girou,-* calves produced from a red
cow by a black bull, or from a black cow by a red bull, are
not rarely born red, and subsequently become black. I
possess a dog, the daughter of a white terrier by a fox-
coloured bulldog ; as a puppy she was quite white, but when
about six months old a black spot appeared on her nose, and
brown spots on her ears. A\ hen a little older she was badly
wounded on the back, and the hair which grew on the
cicatrix was of a brown colour, apparently derived from
her father. This is the more remarkable, as with most
animals having coloured hair, that which grows on a wounded
surface is white.

In the foregoing cases, the characters which with advancing
age reappeared, were present in the immediately preceding

23 Mr. Teebay, in * The Poultry ^i Quoted by Hofacker, ' IJeber die

Book,' by Mr. Tegetmeier, 1866, p. Eigenschaften,' &c., s. 98.

rZ.

Chap. XIII. REVERSION. 13

generations ; but cliaracters sometimes reappear in tlie same
manner after a much longer interval of time. Thus the
calves of a hornless race of cattle which originated in
Corrientes, though at first quite hornless, as they become
adult sometimes acquire small, crooked, and loose horns ; and
these in succeeding years occasionally become attached to the
skull.^^ White and black Bantams, both of which generally
breed true, sometimes assume as they grow old a saffron or
red plumage. For instance, a first-rate black bantam has
been described, which during three seasons was perfectly
black, but then annually became more and more red ; and it
deserves notice that this tendency to change, whenever it
occurs in a bantam, " is almost certain to prove hereditary."^^
The cuckoo or blue-mottled Dorking cock, when old, is liable
to acquire yellow or orange hackles in place of his proper
bluish-grey hackles.^^ Now as Gallus hanhiva is coloured red
and orange, and as Dorking fowls and bantams are descended
from this species, we can hardly doubt that the change which
occasionally occurs in the plumage of these birds as their age
advances, results from a tendency in the individual to revert
to the primitive type.

Crossing as a direct cause of Beversion. — It has long been
notorious that hybrids and mongrels often revert to both or
to one of their parent-forms, after an interval of from two to
seven or eight, or, according to some authorities, even a greater
number of generations. But that the act of crossing in itself
gives an impulse towards reversion, as shown by the reap-
pearance of long-lost characters, has never, I believe, been
hitherto proved. The proof lies in certain peculiarities, which
do not characterise the immediate parents, and therefore can-
not have been derived from them, frequently appearing in the
offspring of two breeds when crossed, which peculiarities
never appear, or appear with extreme rarity, in these same
breeds, as long as they are precluded from crossing. As this

«5 Azara, ' Essais Hist. Nat. de 'The Poultiy Book,' by Mr. Teget-

Paraguay,' torn. ii. 1801, p. 372. meier, 1866, p. 248.

2« These facts are given on the ^7 i^^he Poultry Book,' by Teget-

high authority of Mr. Hewitt, in meier, 1866, p. 97.

23

14 INHERITANCE. Chap. XIIL

conclusion seems to me liiglily curious and novel, I will give
the evidence in detail.

My attention was first called to this subject, and I was led to
make numerous experiments, by BIM. Boitard and Corbie having
stated that, when they crossed certain breeds of pigeons, birds
coloured like the wild C. liuia, or the common dovecot— namely,
slaty-blue, wdth double black wing-bars, sometimes chequered
w'ith black, white loins, the tail barred with black, with the outer
feathers edged w'ith wliite, — were almost invariably produced. The
breeds which I crossed, and the remarkable results attained, have
been fully described in the sixth chapter. I selected pigeons
belonging to true and ancient breeds, which had not a trace of blue
or any of the above specified marks ; but when crossed, and their
mongrels recrossed, yomig birds were often produced, more or less
plainly coloured slaty-blue, with some or all of the i3roper charac-
teristic marks. I may recall to the reader's memory one case,
namely, that of a pigeon, hardly distinguishable from the ■wild
Shetland species, the grandchild of a red-spot, white fantail, and
two black barbs, from any of which, when purelj^-bred, the produc-
tion of a pigeon coloured like the wild C. liuia would have been
almost a prodigy.

I was thus led to make the experiments, recorded in the seventh
chapter, on fowls. I selected long-established pure breeds, in
which there was not a trace of red, yet in several of the mongrels
feathers of this colour appeared ; and one magnificent bird, the
offspring of a black Spanish cock and white Silk hen, was coloured
almost exactly like the wild G alius hankiva. All who know any-
thing of the breeding of poultry will admit that tens of thousands
of pure Spanish and of pure white Silk fowls might have been
reared without the appearance of a red feather. The fact, given on
the authority of Mr. Tegetmeier, of the frequent appearance, in
mongrel fowls, of pencilled or transversely-barred feathers, like
those common to many gallinaceous birds, is likewise apparently a
case of reversion to a character formerly possessed by some ancient
progenitor of the family. I owe to the kindness of this excellent
observer the opportunity of inspecting some neck-hackles and tail-
feathers from a hybrid between the common fowl and a very distinct
species, the Gallus varius ; and these feathers are transversely
striped in a conspicuous manner with dark metallic blue and grey,
a character w^hich could not have been derived from either immediate
parent.

I have been informed by Mr. B. P. Brent, that he crossed a white
Aylesbury drake and a black so-called Labrador duck, both of
which are true breeds, and he obtained a young drake closely like
the mallard [A. hoschas). Of the musk-duck {Cairina moschata, Linn.)
there are two sub-breeds, namely, white and slate-coloured; and these
I am informed breed true, or nearly true. But the Rev. W. D. Fox
tells me that, by putting a wliite drake to a slate-coloured duck,

Chap. XIIL EEVEESION. ' 15

black birds, pied with white, like the wild musk-duck, were always
produced, I hear from Mr. Blyth that hybrids from the canary
and gold-finch almost always have streaked feathers on their backs ;
and this streaking must be derived from the original wild canary.

We have seen in the fourth chapter, that the so-called Himalayan
rabbit, with its snow-white body, black ears, nose, tail, and feet,
breeds perfectly true. This race is known to have been formed by
the union of two varieties of silver-grey rabbits. Now, when a
Himalayan doe was crossed by a sandy-coloured buck, a silver-grey
rabbit was produced ; and this is evidently a case of reversion to
one of the parent varieties. The young of the Himalayan rabbit are
born snow-white, and the dark marks do not appear until some
time subsequently ; but occasionally young Himalayan rabbits are
born of a light silver-grey, which colour soon disappears ; so that
here we have a trace of reversion, during an early i3eriod of life, to
the parent varieties, independently of any recent cross.

In the third chapter it was shown that at an ancient period
some breeds of cattle in the wilder parts of Britain were white with
dark ears, and that the cattle now kept half wild in certain parks,
and those which have run quite wild in two distant parts of the
world, are likewise thus coloured. Now, an experienced breeder,
Mr. J. Beasley, of Northamptonshire,^^ crossed some carefully
selected West Highland cows with purely-bred shorthorn bulls.
The bulls were red, red and white, or dark roan ; and the Highland
cows were all of a red colour, inclining to a light or yellow shade.
But a considerable number of the offspring — and Mr. Beasley calls
attention to this as a remarkable fact — were white, or white with
red ears. Bearing in mind that none of the parents were white,
and that they were purely-bred animals, it is highly probable that
here the offspring reverted, in consequence of the cross, to the
colour of some ancient and half- wild parent-breed. The following
case, perhaps, comes under the same head : cows in their natural
state have their udders but little developed, and do not yield nearly
so much milk as our domesticated animals. Now there is some
reason to believe ^^ that cross-bred animals between two kinds, both
of which are good milkers, such as Alderneys and Shorthorns, often
turn out worthless in this respect.

In the chapter on the Horse reasons were assigned for believing
that the primitive stock was striped and dun-coloured ; and details
were given, showing that in all parts of the world stripes of a dark
colour frequently appear along the spine, across the legs, and on
the shoulders, where they are occasionally double or treble, and
even sometimes on the face and body of horses of all breeds and of
all colours. But the stripes appear most frequently on the various

2" ' Gardeuer's Chron. and Agri- of cattle as Mr. Willougbby Wood

cultural Gazette,' 18G6, p. 528. (' Gard. Chron.' 1869, p. 1216), admits

^^ Ibid., I860, p. 343. I am glad my principle of a cross giving a

to find that so experienced a breeder tendency to reversion.

16 INHERITANCE. Chap. XIIL

kinds of duns. In foals they are sometimes plainly seen, and
subsequently disappear. The dun-colour and the stripes are
strongly transmitted when a horse thus characterised is crossed
with any other ; but I was not able to prove that striped duns are
generally produced from the crossing of two distinct breeds, neither
of which are duns, though this does sometimes occur.

The legs of the ass are often striped, and this may considered as
a reversion to the wild parent form, the Equus tseniopus of Abyssinia,^*^
which is generally thus striped. In the domestic animal the stripes
on the shoulder are occasioiially double, or forked at the extremity,
as in certain zebrine species. There is reason to believe that the
foal is more frequently striped on the legs than the adult animal.
As with the horse, I have not acquired any distinct evidence that
the crossing of differently-coloured varieties of the ass brings out
the stripes.

But now let us turn to the result of crossing the horse and ass.
Although mules are not nearly so numerous in England as asses,
I have seen a much greater number with striped legs, and with
the stripes far more conspicuous than in either parent-form. Such
mules are generally light-coloured, and might be called fallow-
duns. The shoulder-stripe in one instance w^as deeply forked at the
extremity, and in another instance was double, though united in the
middle. Mr, Martin gives a figure of a Spanish mule with strong
zebra-like marks on its legs,^^ and remarks that mules are particu-
larly liable to be thus striped on their legs. In South America,
according to Roulin,^^ such stripes are more frequent and con-
spicuous in the mule than in the ass. In the United States, Mr.
Gosse,^^ speakinii; of these animals, says, " that in a great number,
" perhaps in nine out of every ten, the legs are banded with
" transverse dark stripes."

Many years ago I saw in the Zoological Gardens a curious triple
hybrid, from a bay mare, by a hybrid from a male ass and female
zebra. This animal when old had hardly any stripes; but I was
assured by the superintendent, that when young it had shoulder-
stripes, and faint stripes on its flanks and legs. I mention this case
more especially as an instance of the stripes being much j)lainer
during youth than in old age.

As the zebra has such a conspicuously striped body and legs, it
might have been expected that the hybrids from this animal and
the common ass would have had their legs in some degree stripped ;
but it appears from the figures given in Dr. Gray's 'Knowsley
Gleanings,' and still more plainly from that given by Geoffroy and
F. Cuvier,^* that the legs are much more conspicuously striped than
the rest of the body ; and this fact is intelligible only on the belief

30 Sclater, in ' Proc. Zoolog. Soc.,' 1835, p. 338.

1862, p. 163. ^3 ' Letters from Alabama,' 1859, p.

31 ' History of the Horse,' p. 212. 280.

32 'Alem. presentes par divers ^4 'Hist. Nat. des Mammiferes,'
Savans a I'Acad. Royale,' torn. vi. 1820, torn. i.

Chap. XIII.

EEVERSION,

17

that the ass aids in gi^^ng, through the power of reversion, this
character to its hybrid offspring.

The quagga is banded over the whole front part of its body like
a zebra, but has no stripes on its legs, or mere traces of them. Bnt
in the famous hybrid bred by Lord Morton,^^ from a chestnut,
nearly purely-bred, Arabian mare, by a male quagga, the stripes
were " more strongly defined and darker than those on the legs of
" the quagga." The mare was subsequently put to a black Arabian
liorse, and bore two colts, both of which, as formerly stated, were
plainly striped on the legs, and one of them likewise had striiDes on
the neck and body.

The Equus indicus^^ is cliaracterised by a spinal stripe, without
shoulder or leg stripes; but traces of these latter stripes may occa-
sionally be seen even in the adult ;^^ and Colonel S. Poole, who has
had ample opportunities for observation, informs me that in the
foal, when first born, the head and legs are often striped, but the
shoulder-stripe is not so distinct as in the domestic ass ; all these
stripes, excepting that along the spine, soon disappear. Now a
hybrid, raised at Knowsley^^ from a female of this species by a
male domestic ass, had all four legs transversely and conspicuously
striped, had three short stripes on each shoulder and had even some
zebra-like stripes on its face! Dr. Gray informs me that he has
seen a second hybrid of the same parentage similarly striped.

From these facts we see that the crossing of the several equine
species tends in a marked manner to cause stripes to appear on
various parts of the body, especially on the legs. As we do not
know whether the parent-form of the genus was striped, the appear-
ance of the stripes can only hypothetically be attributed to reversion.
But most persons, after considering the many undoubted cases of
variously coloured marks reappearing by reversion in my experi-
ments on crossed pigeons and fowls, will come to the same conclu-
sion with respect to the horse-genus; and if so, we must admit
that the progenitor of the group was striped on the legs, shoulders,
iace, and probably over the whole body, like a zebra.

Lastly, Professor Jaeger has given ^^ a good case with pigs. He

^^ ' Phiiosoph. Transact.,' 1821, p.
20.

^^ Sclater, in ' Proc. Zoolog. f'yC.,'
1862, p. 163: this species ij the
Ghor-Khur of N.W. India, and has
often been called the Hemionus of
Pallas. See, also, Mr. Blyth's ex-
cellent paper in ' Journal of Asiatic
Soc. of Bengal,' vol. xxviii., 1860, p.
229.

^' Another species of wild ass, the
true U. hemiomis or Kiang, which
ordinarily has no shoulder-sti'ipes, is
said occasionally to have them ; and

these, as with the horse and ass, are
sometimes double : see Mr. Blyth, in
the paper just quoted, and in 'Indian
Sporting Keview,' 1856, p. 320: and
Col. Hamilton Smith, in 'Xat. Library,
Horses,' p. 318; and 'Diet. Class.
d'Hist. Nat.,' tom. iii. p. 563.

^^ Figured in the ' Gleanings from
the Knowsley Menageries,' by Dr. J.
E. Gray.

^^ ' Darwin'sche Theorie und ihre
Stellung zu Moral und Keligion,' ji,
85.

18

INHEEITANCE.

Chap. XHI.

crossed tlie Japanese or masked breed with the common German
breed, and the offspring were intermediate in character. He then
re-crossed one of these mongrels with the pure Japanese, and in
the litter thns produced one of the young resembled in all its
characters a wild pig ; it had a long snout and upright ears, and
was striped on the back. It should be borne in mind that the
young of the Japanese breed are not striped, and that they have
a short muzzle and ears remarkably dependent.

A similar tendency to the recovery of long lost characters
holds good even with the instincts of crossed animals. There
arc some breeds of fowls which are called " everlasting
la^^ers," because they have lost the instinct of incubation ;
and so rare is it for them to incubate that I have seen notices
published in works on poultry, when hens of such breeds have
taken to sit.^° Yet the aboriginal species was of course a
good incubator ; and with birds in a state of nature hardly
any instinct is so strong as this. Xoav, so many cases have
been recorded of the crossed offspring from two races, neither
of which are incubators, becoming first-rate sitters, that the
reappearance of this instinct must be attributed to reversion
from crossing. One author goes so far as to say, " that a cross
between two non- sitting varieties almost invariably produces
a mongrel that becomes broody, and sits with remarkable
steadiness." *^ Another author, after giving a striking ex-
ample, remarks that the fact can be explained only on the
principle that " two negatives make a positive." It cannot,
however, be maintained that hens produced from a cross

** Cases of both Spanish and Polish
hens sitting are given in the ' PouUry
Chronicle,' 1855, vol. iii. p. 477.

41 'The Poultry Book,' by Mr.
Tegetmeier, 1866, pp. 119, 163. The
author, who remarks on the two
negatives (' Journ. of Hort.,' 1862,
p. 325), states that two broods were
raised from a Spanish cock and Silver-
pencilled Hamburg hen, neither of
which are incubators, and no less
than seven out of eight hens in these
two broods " showed a perfect ob-
stinacy in sitting." The Rev. E. S.
Dixon (' Ornamental Poultry,' 1848,
p. 200) says that chickens reared

from a cross between Golden and
Black Polish fowls, are " good and
steady birds to sit." Mr. B. P. Brent
informs me that he raised some good
sitting hens by crossing Pencilled
Hamburg and Polish breeds. A
cross-bred bird from a Spanish non-
incubating cock and Cochin incu-
bating hen is mentioned in the 'Poultry
Chronicle,' vol. iii. p. 13, as an "ex-
emplary mother." On the other
hand, an exceptional case is given in
the 'Cottage Gardener,' 1860^ p. 388,
of a hen raised from a Spanish cock
and black Polish hen which did not
incubate.

Chap. XIII. REVERSION. 19

between two non-sitting breeds invariably recover tlieir lost
instinct, any more than that crossed fowls or pigeons invari-
ably recover the red or blue plumage of their prototypes. Thus
I raised several chickens from a Polish hen by a Spanish
cock, — breeds which do not incubate, — and none of the young
hens at first showed any tendency to sit ; but one of them —
the only one which was preserved — in the third year sat well
on her eggs and reared a brood of chickens. So that here we
have the reappearance with advancing age of a primitive
instinct, in the same manner as we have seen that the red
plumage of the Gallas hanldva is sometimes reacquired both
b}^ crossed and purely -bred fowls of various kinds as they
grow old.

The parents of all our domesticated animals were of course
aboriginally wild in disposition ; and when a domesticated
species is crossed with a distinct species, whether this is a
domesticated or only a tamed animal, the hybrids are often
wild to such a degree, that the fact is intelligible only on the
principle that the cross has caused a partial return to a
primitive disposition. Thus, the Earl of Powis formerly im-
ported some thoroughly domesticated humped cattle from
India, and crossed them with English breeds, which belong to
a distinct species ; and his agent remarked to me, without
any question having been a«ked, how oddly wild the cross-
bred animals were. The European wild boar and the Chinese
domesticated pig are almost certainly specifically distinct:
Sir F. Darwin crossed a sow of the latter breed with a wild
Alpine boar which had become extremely tame, but the young,
though having half-domesticated blood in their veins, were
*' extremely wild in confinement, and would not eat swill like
common English pigs." Captain Hutton, in India, crossed a
tame goat with a wild one from the Himalaya, and he re-
marked to me how surprisingly wild the oifspring were.
Mr. Hewitt, who has had great experience in crossing tame
cock-pheasants with fowls belonging to five breeds, gives as
the character of all " extraordinary wildness ;"'^^ but I have
myself seen one exception to this rule. Mr. S. J. Salter,*^

« 'The Poultry Book,' by Teget- " ' Natural Ili.-.toiy lievicw,' 1863.

meier, 1866, pp. 165, 167. A]>ril, p. 277.

20 INHERITANCE. Chap. XIII.

wlio raised a large mimber of hybrids from a bantam-hen by
Gallus sonneraiii, states that "all were exceedingly wild."
Mr. Waterton ^* bred some wild ducks from eggs hatched
under a common duck, and the young were allowed to cross
freely both amongst themselves and with the tame ducks ;
they were " half wild and half tame ; they came to the
windows to be fed, but still they had a wariness about them
quite remarkable."

On the other hand, mules from the horse and ass are
certainly not in the least wild, though notorious for obstinacy
and "vice. Mr. Brent, who has crossed canary-birds with
many kinds of finches, has not obsei'ved, as he informs me,
that the hybrids were in any way remarkably wild : but
Mr. Jenner Weir who has had still greater experience, is of a
directly opposite opinion. He remarks that the siskin is the
tamest of finches, but its mules are as wild, when young, as
newly caught birds, and are often lost through their continued
efforts to escape. Hybrids are often raised between the
common and musk duck, and I have been assured by three
persons, who have kept these crossed birds, that they were
not wild ; but Mr. Garnett*^ observed that his hybrids were
wild, and exhibited " migratory propensities " of which there
is not a vestige in the common or musk duck. Ko case is
known of this latter bird having escaped and become wild in
Europe or Asia, except, according to Pallas, on the Caspian
Sea ; and the common domestic duck only occasionally becomes
wild in districts where large lakes and fens abound. Never-
theless, a large number of cases have been recorded*^ of
hybrids from these two ducks having been shot in a com-
pletely wild state, although so few are reared in comparison
with purely-bred birds of either species. It is im23robable
that any of these hybrids could have acquired their wildness

** 'Essays on Natural History,' p. asserts (' Zoologist,' vol. v., 184-5-46,

917. p. 1254) that several have been shot

*^ As stated by Mr. Orton, in his in various parts of Belgium and

' Physiology of Breeding,' p. 12. Northern France. Audubon (' Ornith-

*^ M. E, de Selys-Longchamps olog. Biography,' vol. iii. p. 1(J8),

refers (' Bulletin Acad. Roy. de Brux- speaking of these hybrids, says that,

elles,' torn. xii. No. 10) to more than in North America, they " now and

seven of these hybrids shot in then wander off and become quite

Switzerland and France. M, Deby wild."

CuAP. XIII. REVERSION. 21

from the musk-duck having paired with a truly wild duck ;
aud this is known not to be the case in North America ; hence
we must infer that they have reacquired, through reversion,
their wildness, as well as renewed powers of flight.

These latter facts remind us of the statements, so frequently
made by travellers in all parts of the world, on the degraded
state and savage disposition of crossed races of man. That
many excellent and kind-hearted mulattos have existed no one
will dispute ; and a more mild and gentle set of men could
hardly be found than the inhabitants of the island of Chiloe,
who consist of Indians commingled with Spaniards in various
proportions. On the other hand, man}^ years ago, long before
I had thought of the present subject, I was struck Avith the
fact that, in South America, men of complicated descent
between Negroes, Indians, and Spaniards, seldom had, what-
ever the cause might be, a good expression.'^' Livingstone, —
and a more unimpeachable authority cannot be quoted, — after
speaking of a half-caste man on the Zambesi, described by the
Portuguese as a rare monster of inhumanity, remarks, " It is
unaccountable why half-castes, such as he, are so much more
cruel than the Portuguese, but such is undoubtedly the case."
An inhabitant remarked to Livingstone, " God made white
men, and God made black men, but the Devil made half-
castes." '^^ When two races, both low in the scale, are crossed
the progeny seems to be eminentl}'' bad. Thus the noble-
hearted Humboldt, who felt no prejudice against the inferior
races, speaks in strong terms of the bad and savage disposition
of Zambos, or half-castes between Indians and Negroes ; and
this conclusion has been arrived at by various observers.*^
From these facts we may perhaps infer that the degraded state
of so many half-castes is in part due to reversion to a primitive
and savage condition, induced by the act of crossing, even if
mainly due to the unfavourable moral conditions under which
they are generally reared.

Summary on tJie jproximate causes leading to Reversion. — When

*^ 'Journal of Researches,' 1845, ^^ Dr. P. Broca, on ' Hybridity in

p. 71. the Genus Homo,' Eng. translat.,

48 ' Expedition to the Zambesi,' 1864, p. 39.
1865, pp. 25, 150.

22 INHERITANCE. Chap. XIII.

purely- bred animals or plants reassiime long-lost characters,—
when the common ass, for instance, is born with striped legs,
when a pure race of black or white pigeons throAvs a slaty-
blue bird, or when a cultivated heartsease with large and
rounded flowers produces a seedling with small and elongated
flowers, — we are quite unable to assign any proximate cause.
When animals run wild, the tendency to reversion, which,
though it has been greatly exaggerated, no doubt exists, is
sometimes to a certain extent intelligible. Thus, with feral
pigs, exposure to the weather will probably favour the growth
of the bristles, as is known to be the case with the hair of
other domesticated animals, and through correlation the tusks
will tend to be redeveloped. But the reappearance of coloured
longitudinal stripes on j^oung feral pigs cannot be attributed
to the direct action of external conditions. In this case, and
in many others, we can only say that any change in the
habits of life apjoarently favour a tendency, inherent or latent
in the species, to return to the primitive state.

It will be shown in a future chapter that the position of
flowers on the summit of the axis, and the position of seeds
within the capsule, sometimes determine a tendency towards
reversion ; and this apparently depends on the amount of sap
or nutriment which the flower-buds and seeds receive. The
position, also, of buds, either on branches or on roots, some-
times determines, as was formerl}^ shown, the transmission of
the character proper to the variet}^, or its reversion to a former
state.

We have seen in the last section that when two races or
species are crossed there is the strongest tendency to the re-
appearance in the offspring of long-lost characters, possessed
by neither parent nor immediate progenitor. When two
white, or red, or black j)igeons, of well-established breeds,
are united, the ofispring are almost sure to inherit the same
colours ; but when differently-coloured bii ds are crossed, the
opposed forces of inheritance apparently counteract each
other, and the tendency which is inherent in both parents to
produce slaty-blue offspring becomes predominant. So it is
in several other cases. But when, for instance, the ass is
crossed with E. indicus or with the horse,— animals which

Chap. XIII. REVEKSION. 23

have not striped legs, — and the hybrids have conspicuous
stripes on their legs and even on their faces, all that can be
said is, that an inherent tendency to reversion is evolved
through some disturbance in the organisation caused by the
act of crossing.

Another form of reversion is far commoner, indeed is almost
universal with the offspring from a cross, namely, to the
characters proper to either pure parent-form. As a genei al
rule, crossed offspring in the first generation are nearly inter-
mediate between their parents, but the grandchildren and
succeeding generations continually revert, in a greater or
lesser degree, to one or both of their progenitors. Several
authors have maintained that hj^brids and mongrels include
all the characters of both parents, not fused together, but
merely mingled in different projiortions in different parts of
the body ; or, as Kaudin ^° has expressed it, a h^^brid is a
living mosaic- work, in which the eye cannot distinguish the
discordant elements, so completely are they intermingled.
AVe can hardly doubt that, in a certain sense, this is true, as
when we behold in a hybrid the elements of both species
segregating themselves into segments in the same flower or
fruit, by a process of self-attraction or self-affinity ; this
segregation taking place either by seminal or bud-propagation.
Naudin further believes that the segregation of the two
specific elements or essences is eminently liable to occur in
the male and female reproductive matter ; and he thus
explains the almost universal tendency to reversion in succes-
sive hybrid generations. For this would be the natural
result of the union of pollen and ovules, in both of which the
elements of the same species had been segregated by self-
affinity. If, on the other hand, pollen w^hich included the
elements of one species happened to unite with ovules includ-
ing the elements of the other species, the intermediate or
hybrid state would still be retained, and there would be
no reversion. But it would, as I suspect, be more correct
to say that the elements of both parent-species exist in every
hybrid in a double state, namely, blended together and com-

** 'Nouvelles Archives du Museum,' torn, i, p. 151.

24 INHERITANCE. Chap. XIIL

pletely separate. How this is possible, and what the term
specific essence or element may be supposed to express, I shall
attempt to show in the chapter on the hypothesis of pangenesis.

But Naudin's view, as propounded by him, is not applicable
to the reappearance of characters lost long ago by variation ;
and it is hardly applicable to races or species which, after
having been crossed at some former period with a distinct
form, and having since lost all traces of the cross, neverthe-
less occasionally yield an individual which reverts (as in the
case of the great-great-grandchild of the pointer Sappho) to
the crossing form. The most simple case of reversion, name! 3^,
of a hybrid or mongrel to its grandparents, is connected by an
almost perfect series with the extreme case of a purely-bred
race recovering characters which had been lost during many
ages ; and we are thus led to infer that all the cases must be
related by some common bond.

Gartner believed that only highly sterile hybrid plants ex-
hibit any tendency to reversion to their parent-forms. This
erroneous belief iiiaj perhaps be accounted for by the nature
of the genera crossed by him, for he admits that the tendency
dijBfers in different genera. The statement is also directly con-
tradicted by Naudin's observations, and by the notorious fact
that perfectl}^ fertile mongrels exhibit the tendency in a high
degree, — even in a higher degree, according to Gartner
himself, than hybrids. ^^

Gartner further states that reversions rarely occur with
hybrid plants raised from species which have not been culti-
vated, whilst, with those which have been long cultivated,
they are of frequent occurrence. This conclusion explains
a curious discrepancy : Max Wichura,^^ who worked exclu-
sively on willows which had not been subjected to culture,
never saw an instance of reversion ; and he goes so far as to
suspect that the careful Gartner had not suflicientl}^ protected
his hybrids from the pollen of the parent-species : Naudin, on
the other hand, who chiefly experimented on cucurbitaceous and
other cultivated plants, insists more strenuously than any other

** ' Bastarderzeugung,' s. 582, 438, der Weiden,' 1865, s. 23. For Gartner's
&c. remarks on this head, see 'Bastard-

*2 ' Die Bastardbefruchtuug . . . erzeugung,' s. 474, 582.

Chai'. XIII. REVERSION. 25

author on tlio tendency to reversion in all hybrids. The con-
clusion that the condition of the parent-species, as affected by
culture, is one of the proximate causes leading to reversion,
agrees well with the converse case of domesticated animals and
cultivated plants being liable to reversion when they become
feral ; for in both cases the organisation or constitution must
be disturbed, though in a very different way.^^

Finally, we have seen that characters often reappear in
purely-bred races without our being able to assign any
proximate cause ; but when they become feral this is either
indirectly or directly induced by the change in their condi-
tions of life. With crossed breeds, the act of crossing in
itself certainly leads to the recovery of long-lost characters,
as well as of those derived from either parent-form. Changed
conditions, consequent on cultivation, and the relative position
of buds, flowers, and seeds on the plant, all apparently aid in
giving this same tendency. Eeversion may occur either
through seminal or bud generation, generally at birth, but
sometimes only with an advance of age. Segments or portions
of the individual may alone be thus affected. That a being
should be born resembling in certain characters an ancestor
removed by two or three, and in some cases by hundreds or
even thousands of generations, is assuredly a wonderful fact.
In these cases the child is commonly said to inherit such
characters directly from its grandparent, or more rfimote
ancestors. But this view is hardly conceivable. If, however,
we suppose that every character is derived exclusively from
the father or mother, but that many characters lie latent or
dormant in both parents during a long succession of genera-
tions, the foregoing facts are intelligible. In what manner
characters may be conceived to lie latent, will be considered
in a future chapter to which I have lately alluded.

Latent Characters. — But I must explain what is meant by

^^ Prof. Weismann, in his very elusion, namely, that any cause which

curious essay on the diti'erent forms disturbs the organisation, such as the

produced by the same species of exposure of the cocoons to heat or

butterfly at different seasons (' Saison- eA^en to much shaking, gives a

Dimorphismus der Schmetterlinge,' pp. tendency to reversion.
27, 28), has come to a similar con-

26

INHEEITAXCE.

Chap. XIII,

characters lying latent. The niost obvious illustration is
aiforded by secondary sexual characters. In every female all
the secondary male charactei's, and in every male all the
secondary female characters, apparently exist in a latent
state, ready to be evolved under certain conditions. It is
well known that a large number of female birds, such as
fowls, various pheasants, partridges, peahens, ducks, &c.,
when old or diseased, or when operated on, assume many or
all of the secondary male characters of their sj)ecies. In
the case of the hen-pheasant this has been observed to occur
far more frequently during certain years than during others.^*
A duck ten years old has been known to assume both the
perfect winter and summer plumage of the drake.^^ Water-
ton ^^ gives a curious case of a hen which had ceased laying,
and had assumed the plumage, voice, spurs, and w^arlike
disposition of the cock ; when opposed to an enemy she would
erect her hackles and show fight. Thus everj character, even
to the instinct and manner of fighting, must have lain
dormant in this hen as long as her ovaria continued to act.
The females of two kinds of deer, when old, have been known
to acquire horns ; and, as Hunter has remarked, we see some-
thing of an analogous nature in the human species.

On the other hand, with male animals, it is notorious that
the secondary sexual characters are more or less completely
lost when they are subjected to castration. Thus, if the
operation be i^erformed on a young cock, he never, as Yarrell
states, crows again ; the comb, wattles, and spurs do not grow
to their full size, and the hackles assume an intermediate
appearance between true hackles and the feathers of the hen.
Cases are recorded of confinement, which often afiects the
reproductive system, causing analogous results. But clia-

5* Yarrell, 'Phil. Transact.,' 1827,
p. 268 ; Dr. Hamilton, iu ' Proc.
Zoolog. Soc.,' 1862, p. 23.

^^ ' Archiv. Skand. Beitrage zur
Naturgesch.' viii. s. 397-413.

*^ In his 'Essays on Nat. Hist.,'
1838, Mr. Hewitt gives analogous
cases with hen-pheasants in ' Journal
of Horticulture, July 12, 1864, p. 37.

Isidore Geoffroy Saint-Hilaire, in his
' Essais de Zoolog. Gen.' (' suites a
Buffon,' 1842, pp. 496-513), has
collected such cases in ten different
kinds of birds. It appears that
Aristotle was well aware of the
change in mental disposition in old
hens. The case of the female deer
acquiring horns is given at p. 513.

Chap. XIII. REVERSION. 27

racters properly confined to tlie feruale are likewise acquired
by the male ; tlie capon takes to sitting on eggs, and will
bring uj) cliickens ; and what is more curious, the utterly
sterile male hybrids from the pheasant and the fowl act in
the same manner, " their delight being to watch when the
hens leave their nests, and to take on themselves the oifice of
a sitter." ^^ That admirable observer Eeaumnr ^^ asserts that
a cock, by being long confined in solitude and darkness, can
be taught to take charge of yomig chickens ; he then utters
a peculiar cr}'^, and retains during his whole life this newly
acquired maternal instinct. The many well-ascertained cases
of various male mammals giving milk shows that their rudi-
mentary mammar}^ glands retain this capacity m a latent
condition.

We thus see that in man}^ probably in all cases, the
secondary characters of each sex lie dormant or latent in the
opposite sex, ready to be evolved under peculiar circumstances.
We can thus understand how, for instance, it is possible for
a good milking cow to transmit her good qualities through
her male offspring to future generations ; for we may confi-
dently believe that these qualities are present, though latent,
in the males of each generation. So it is with the game-cock,
who can transmit his superiority in courage and vigour
through his female to his male offspring ; and with man it is
known ^^ that diseases, such as hydrocele, necessarily confined
to the male sex, can be transmitted through the female to the
grandson. Such cases as these offer, as was remarked at the
commencement of this chapter, the simplest possible examples
of reversion ; and they are intelligible on the belief that
characters common to the grandf)arent and grandchild of the
same sex are present, though latent, in the intermediate
parent of the opposite sex.

The subject of latent characters is so important, as we shall
see in a future chapter, that I will give another illustration.
Many animals have the right and left sides of their body

" ' Cottage Gardener,' 18G0, p. ^» Sir H. Holland, ' Medical Notes

379. and Reflections,' 3rd edit., 1855, p.

^8 'Art de faire Eclore,' &c., 1749, 31.
torn. ii. p. 8.

28 INHEEITANCE. Chap. XIII.

unoqiially developed : this is well known to be the case with
flat-fish, in which the one side differs in thickness and colour
and in the shape of the fins, from the other, and during the
growth of the young fish one eye is gradually twisted from
the lower to the upper surface. ^° In most flat-fishes the left
is the blind side, but in some it is the right ; though in both
cases reversed or" wrong fishes," are occasionally developed ;
and in Platessa flesiis the right or left side is indifferently the
upper one. With gasteropods or shell-fish, the right and left
sides are extremely unlike ; the far greater number of species
are dextral, with rare and occasional reversals of development,
and some few are normally sinistral ; but certain species of
Bulimus, and many Achatinella3,"^ are as often sinistral as
dextral. I will give an analogous case in the great articulate
kingdom : the two sides of Verruca*^^ are so wonderfully
unlike, that without careful dissection it is extremely difficult
to recognise the corresponding parts on the oj^posite sides of
the body; yet it is apparently a mere matter of chance
whether it be the right or the left side that undergoes so
singular amount of change. One plant is known to me ^^ in
which the flower, according as it stands on the one or other
side of the spike, is unequally developed. In all the foregoing
cases the two sides are perfectly symmetrical at an early
period of growth. Now, whenever a species is as liable to be
unequally developed on the one as on the other side, we may
infer that the capacity for such development is present,
though latent, in the undeveloped side. And as a reversal of
development occasionally occurs in animals of many kinds,
this latent capacity is probably very common.

The best jQt simplest cases of characters lying dormant
are, perhaps, those previously given, in which chickens and
young pigeons, raised from a cross between differently coloured

«<> See Steenstrup on the ' Obliquity p. 209,

of Flounders' : in ' Annals and Mag. of ^"^ Darwin, ' Balanidw,' Ray Soc,

Nat. Hist.' May, 1865, p. 361. I 1854, p. 499 : see also the appended

have given an abstract of Malm's remarks on the apparently capricious

explanation of this wonderful pheno- development of the thoracic limbs on

menon in the ' Origin of Species' 6th the right and left sides in the higher

Edit. p. 186. crustaceans.

''* Dr. E. von Martens, in ' Annals *•' Mormodes ignea : Darwin, ' Fer-

and Mag. of Nat. Hist.' March, 1866, tilisation of Orchids,' 1862, p. 251,

Chap. XIll. EEVERSION. 29

birds, are at first of one colour, but in a j-ear or two acquire
featliers of the colour of the other parent ; for in this case the
tendency to a change of plumage is clearly latent in the young
bird. So it is with hornless breeds of cattle, some of which
acquire small horns as they grow old. Purely bred black and
white bantams, and some other fowls, occasionally assume, with
advancing years, the red feathers of the parent-sf)ecies. I will
here add a somewhat different case, as it connects in a striking
manner latent characters of two classes. Mr. Hewitt ^^ pos-
sessed an excellent Sebright gold-laced bantam hen, which,
as she became old, grew diseased in her ovaria, and assumed
male characters. In this breed the males resemble the females
in all respects except in their combs, wattles, sjDurs, and
instincts ; hence it might have been expected that the diseased
hen would have assumed only those masculine characters
which are proper to the breed, but she acquired, in addition,
well-arched tail sickle-feathers quite a foot in length, saddle-
feathers on the loins, and hackles on the neck, — ornaments
which, as Mr. Hewitt remarks, " would be held as abominable
in this breed." The Sebright bantam is known ^^ to have
originated about the year 1800 from a cross between a common
bantam and a Polish fowl, recrossed by a hen-tailed bantam,
and carefully selected ; hence there can hardly be a doubt
that the sickle-feathers and hackles which appeared in the old
hen were derived from the Polish fowl or common bantam ; and
we thus see that not only certain masculine characters proper
to the Sebright bantam, but other masculine characters derived
from the first progenitors of the breed, removed by a period of
above sixty years, were lying latent in this henbird, ready
to be evolved as soon as her ovaria became diseased.

From these several facts it must be admitted that certain
characters, capacities, and instincts, may lie latent in an indi-
vidual, and even in a succession of individuals, without our
being able to detect the least sign of their presence. When
fowls, pigeons, or cattle of different colours are crossed, and

^* ' Journal of Horticulture,' July, Tegetmeier.
1864, p. 38. I have had the oppor- " 'The Poultry Book,' by Mr.

tunity of examining these remarkable Tegetmeier, 1866, p. 241.
feathers through the kindness of Mr.

30 INHERITANCE. Chap. XIII,

their offspring change colour as they grow okl, or when the
crossed turbit acquired the characteristic frill after its third
moult, or when p arely-bred bantams partially assume the red
plumage of their prototype, we cannot doubt that these
qualities were from the first present, though latent, in the
individual animal, like the characters of a moth in the cater-
pillar. Now, if these animals had produced offspring before
they had acquired with advancing age their new characters,
nothing is more probable than that they would have trans-
mitted them to some of their offspring, who in this case would
in appearance have received such characters from their grand-
parents or more distant progenitors. AVe should then have
had a case of reversion, that is, of the reappearance in the
child of an ancestral character, actually present, though
during youth completely latent, in the parent ; and this we
may safely conclude is what occurs in all reversions to pro-
genitors, however remote.

This view of the latency in each generation of all the cha-
racters which appear through reversion, is also sujDported by
their actual presence in some cases during early youth alone,
or by their more frequent appearance and greater distinctness
at this age than during maturity. We have seen that this is
often the case with the stripes on the legs and faces of the
several species of the horse-genus. The Himalayan rabbit,
when crossed, sometimes produces offspring which revert to
the parent silver-grey breed, and we have seen that in purely
bred animals pale-grey fur occasionally reappears during earl}^
youth. Black cats, we may feel assured, would occasionally
produce by reversion tabbies ; and on young black kittens,
with a pedigree '^^ known to have been long pure, faint traces
of stripes may almost always be seen which afterwards dis-
appear. Hornless Suffolk cattle occasionally produce by
reversion horned animals ; and Youatt ''^ asserts that even in
hornless individuals " the rudiment of a horn may be often
felt at an early age."

No doubt it appears at first sight in the highest degree im-
probable that in every horse of every generation there should

«« Carl Vogt, ' Lectures on Man,' ^7 ; Qn Cattle,' p. 174.

Eng. translat., 186-1, p. 411.

CuAT. XIII. EEVEESION. 31

be a latent capacit}? and tendency to produce stripes, though
these may not appear once in a thousand generations ; that in
every white, black, or other coloured pigeon, which may have
transmitted its proper colc^ur during centuries, there should
be a latent capacity in the plumage to become blue and to be
marked with certain characteristic bars ; that in every child
in a six-fingered family there should be the capacity for the
production of an additional digit ; and so in other cases.
Nevertheless, there is no more inherent improbability in this
being the case than in a useless and rudimentary organ, or even
in only a tendency to the production of a rudimentary organ,
being inherited during millions of generations, as is well
known to occur with a multitude of organic beings. There is
no more inherent improbability in each domestic pig, during a
thousand generations, retaining the capacity and tendency to
develop great tusks under fitting conditions, than in the young-
calf having retained for an indefinite number of generations
rudimentary incisor teeth, which never protrude through the
gums.

I shall give at the end of the next chapter a summary of the
three preceding chapters ; but as isolated and striking cases
of reversion have here been chiefl}^ insisted on, I wish to
guard the reader against supposing that reversion is due to
some rare or accidental combination of circumstances. When
a character, lost during hundreds of generations, suddenly
reappears, no doubt some such combination must occur ; but
reversions to the immediately preceding generations may be
constantly observed, at least, in the offspring of most unions.
This has been universally recognised in the case of hybrids
and mongrels, but it has been recognised simply from the
difference between the united forms rendering the resemblance
of the offspring to their grandjoarents or more remote pro-
genitors of easy detection. Eeversion is likewise almost in-
variably the rule, as Mr. Sedgwick has shown, with certain
diseases. Hence we must conclude that a tendency to tliis
peculiar form cf transmission is an integral part of the
general law of inheritance.

Monstrosities. — A large number of monstrous growths and

32 INHEEITANCE. Chap. XIII.

of lesser anomalies aro admitted by every one to be due to an
arrest of development, that is, to the persistence of an embry-
onic condition. But many monstrosities cannot be thus
explained ; for parts of which no trace can be detected in the
embryo, but which occur in other members of the same class
of animals occasionally appear, and these may probably with
truth be attributed to reversion. As, however, I have treated
this subject as fully as I could in my ' Descent of Man '
(chap, i., 2nd edit.), I will not here recur to it.

When flowers which have normally an irregular structure become
regular or peloric, the chauge is generally looked at by botanists as
a return to the primitive state. But Dr. Maxwell Masters, ^'^ who
has ably discussed this subject, remarks that when, for instance, all
the sepals of a Tropseolum become green and of the same shape,
instead of being coloured with one prolonged into a spur, or when
all the petals of a Linaria become simple and regular, such cases
may be due merely to an arrest of development ; for in these flowers
all the organs during their earliest condition are symmetrical, and,
if arrested at this stage of growth, they would not become irregular.
If, moreover, the arrest were to take place at a still earlier period
of development, the result would be a simple tuft of green leaves ;
and no one probably w^ould call this a case of reversion. Dr. Masters
designates the cases first alluded to as regular peloria ; and others,
in which all the corresponding parts assume a similar form of
irregularity, as when all the petals in a Linaria become spurred, as
irregular peloria. We have no right to attribute these latter cases
to reversion, until it can be shown that the parent-form, for instance,
of the genus Linaria had had all its petals spurred ; for a chance of
this nature might result from the spreading of an anomalous
structure, in accordance with the law, to be discussed in a future
chapter, of homologous parts tending to vary in the same manner.
But as both forms of peloria frequently occur on the same intlividual
plant of the Linaria,*^^ they probably stand in some close relation to
one another. On the doctrine that peloria is simply the result of an
arrest of development, it is diificult to understand how an organ
arrested at a very early period of growth should acquire its full
functional perfection ; — how a petal, supposed to be thus arrested
should acquire its brilliaiit colours, and serve as an envelope to the
flower, or a stamen produce efficient pollen ; yet this occurs with

^* ' Natural Hist. Review,' April, cases, Sitzb. d. k. Alv.id. d. Wissensch. :

1863, p. 258. See also his Lecture, Wien. Bd. LX. auJ especially Bd.

Royal Institution, March 16, 1860. LXVI., 1872, p. 125.
On same subject, see Moquin-Tandou, ''^ Verlot, ' Des Varietes,' 1865, p.

' Elements de Teratologie,' 1841, pp. 89; Naudin, ' Nouvelles Archives du

184, 352, Dr. Peyritsch has coUected Museum,' torn. i. p 137.
a large number of very interesting'

Chap. XIII. KEVEKSION. 33

many peloric flox\-ers. That pelorism is not dne to mere chance
variability, but eitlier to an arrest of development or to reversion,
we may infer from an observation made by Ch. Morren/*^ namely,
that families which have irregular flowers often " return by these
monstrous growths to their regular form; whilst we never see a
regular flower realise the structure of an irregular one."

Some flowers have almost certainly become more or less completely
peloric through reversion, as the following interesting case shows.
Corydalis tuberosa properly has one of its two nectaries colourless,
destitute of nectar, only half the size of the other, and therefore, to
a certain extent, in a rudimentary state; the pistil is curved
towards the perfect nectary, and the hood, formed of the inner
petals, slips off the pistil and stamen in one direction alone, so that,
when a bee sucks the perfect nectary, the stigma and stamens are
exposed and rubbed against the insect's body. In several closely
allied genera, as in Dielytra, &c., there are two perfect nectaries,
the pistil is straight, and the hood slips off on either side, accord-
ing as the bee sucks either nectary. Now, I have examined several
flowers of Corydalis tuherosa, in which both nectaries were equally
developed and contained nectar ; in this we see only the redevelop-
ment of a partially aborted organ ; but with this redevelopment the
pistil becomes straight, and the hood sli23S off in either direction ,
so that these flowers have acquired the perfect structure, so well
adapted for insect agency, of Dielytra and its allies. "We cannot
attribute these coadapted modifications to chance, or to correlated
variability; we must attribute them to reversion to a primordial
condition of the species.

The peloric flowers of Pelargonium have their five petals in all
respects alike, and there is no nectary ; so that they resemble the
symmetrical flowers of the closely allied genus Geranium ; but the
alternate stamens are also sometimes destitute of anthers, the
shortened filaments being left as rudiments, and in this respect
they resemble the symmetrical flowers of the closely allied genus
Erodium. Hence we may look at the peloric flowers of Pelargo-
nium as having reverted to the state of some primordial form, the
progenitor of the three closely related genera of Pelargonium,
Geranium, and Erodium.

In the peloric form of Antirrhinum maji's, appropriately called
the " Wonder," the tubular and elongated flowers differ wonderfully
from those of the common snapdragon ; the calyx and the mouth
of the corolla consist of six equal lobes, and include six equal instead
of four unequal stamens. One of the two additional stamens is
manifestly formed by the development of a microscopically minute
papilla, which may be found at the base of the upper lip of the
flower of the common snapdragons in the nineteen plants examined

^* In his discussion on some curious nal of Horticulture,' Feb. 24,1863,
peloric Calceolarias, quoted in ' Jour- p. 152.

34 INHERITANCE. Chap. XIIL

by me. That this papilla is a rudiment of a staroen was well shown
by its Yarious degrees of development in crossed plants between the
common and the peloric Antirrhinnm. Again, a peloric GaJeoh-
dolon Iidemn, growing in my garden, had five equal petals, all striped
like the ordinary lower lip, and included five equal instead of four
unequal stamens ; but Mr. E. Keeley, who sent me this i^lant,
informs me that the flowers vary greatly, having from four to six
lobes to the corolla, and from three to six stamens.^^ Now, as the
members of the two great families to which the Antirrhinum and
Galeobdolon belong are j)roperly pentamerous, with some of the
parts confluent and others suppressed, we ought not to look at the
sixth stamen and the sixth lobe to the corolla in either case as due
to reversion, any more than the additional petals in double flowers
in these same two families. But the case is diiferent with the fifth
stamen in the peloric Antirrhinum, which is produced by tlie
redevelopment of a rudiment always present, and which probably
reveals to us the state of the flower, as ftir as the stamens are con-
cerned, at some ancient epoch. It is also diflicult to believe that
the other four stamens and the i)etals, after an arrest of develop-
ment at a very early embryonic age, would have come to full
perfection in colour, structure, and function, unless these orgnns
had at some former period normally passed through a similar course
of growth. Hence it appears to me probable that the progenitor of
the genus Antirrhinum must at some remote epoch have included
five stamens and borne flowers in some degree resembling those now
produced by the peloric form. The conclusion that peloria is not
a mere monstrosity, irrespective of any former state of the species,
is supported by the fact that this structure is often strongly in-
herited, as in the case of the peloric Antirrhinum and Gloxinia and
sometimes in that of the peloric CorydnUs soJida."''^

Lastly I may add that many instances have been recorded of
flowers, not generally considered as peloric, in which certain
organs are abnormally augmented in number. As an increase
of parts cannot be looked at as an arrest of development, nor as due
to the redevelopment of rudiments, for no rudiments are present,
and as these additional parts bring the plant into closer relationship
with its natural allies, they ought probably to be viewed as rever-
sions to a primordial condition.

These several facts show us in an interesting manner how
intimately certain abnormal states are connected together;
namely, arrests of development causing parts to become rudi-
mentary or to be wholly su2:)pressed,— the redevelopment oi

^^ For other cases of six divisions "- Godron, reprinted from the

in peloric flowers of the Labiatae and * Memoires de I'Acad. de Stanislas,'"

ScrophulariaceEe, see Moquin-Tandon, 1868.
* Teratologie,' p. 1U2.

Chap. XIII. EEVEllblON. 35

parts now in a more or less rudiment a r^^ condition, — the re-
appearance of organs of which not a vestige can be detected,
— and to these may be added, in the case of animals, the
presence during youth, and subsequent disappearance, of cer-
tain characters which occasionally are retained throughout
life. Some naturalists look at all such abnormal structures as
a return to the ideal state of the group to which the affected
beins: belong-s ; but it is difficult to conceive what is meant to
be conveyed by this expression. Other naturalists maintain,
with greater probability and distinctness of view, that the
common bond of connection between the several foregoing
cases is an actual, though partial, return to the structure of
the ancient progenitor of the group. If this view be correct,
we must believe that a vast number of characters, capable of
evolution, lie hidden in every organic being. But it would
be a mistake to suppose that the number is equally great in
all beings. We know, for instance, that plants of many
orders occasionall}^ become peloric ; but many more cases have
been observed in the Labiatse and Scrophulariaceee than in
any other order ; and in one genus of the Scrophulariaceae,
namely Linaria, no less than thirteen species have been de-
scribed in this condition.'^ On this view of the nature of
peloric flowers, and bearing in mind certain monstrosities in
the animal kingdom, Ave must conclude that the progenitors of
most plants and animals have left an impression, capable of
redevelopment, on the germs of their descendants, although
these have since been profoundly modified.

The fertilised germ of one of the higher animals, subjected
as it is to so vast a series of changes from the germinal cell to
old age, — incessantly agitated by what Quatrefages well calls
the toiirhillon vital, — is perhaps the most wonderful object in
nature. It is probable that hardly a change of any kind
affects either parent, without some mark being left on the
germ. But on the doctrine of reversion, as given in this
chapter, the germ becomes a far more marvellous object, for,
besides the visible changes which it undergoes, we must

" Moquin-Tandon, ' Teratologie,' p. 186.

36 INHERITANCE. Chap. XIII.

believe that it is crowded witli invisible characters, proper to
both sexes, to both the right and left side of the body, and
to a long line of ■ male and female ancestors separated by
hundreds or even thousands of generations from the present
time : and these characters, like those written on paper with
invisible ink, lie ready to be evolved whenever the organisa-
tion is disturbed by certain known or unknown conditions.

Ohap. XiV. I:NHERITANCE : FIXEDNESS OF CHARACTER. 37

CHAPTER XIY.

INllERITAXCE continued — FIXEDNESS OF CHARACTER — PREPOTENCY
SEXUAL LIMITATION — CORRESPONDENCE OF AGE.

FIXEDNESS OF CHAEACTER APPARENTLY NOT DVE TO ANTIQUITY OF INHERI-
TANCE—PREPOTENCY OF TRANSMISSION IN INDIVIDUALS OF THE SAME
FAMILY, IN CROSSED BREEDS AND SPECIES ; OFTEN STRONGER IN ONE
SEX THAN THE OTHER ; SOMETIMES DUE TO THE SAME CHARACTER
BEING PRESENT AND VISIBLE IN ONE BREED AND LATENT IN THE OTHER
— INHERITANCE AS LIMITED BY SEX — NEWLY-ACQUIRED CHARACTERS IN
OUR DOMESTICATED ANIMALS OFTEN TRANSMITTED BY ONE SEX ALONE,
SOMETIMES LOST BY ONE SEX ALONE — INHERITANCE AT CORRESPONDING
PERIODS OF LIFE — THE IMPORTANCE OF THE PRINCIPLE WITH RESPECT
TO EMBRYOLOGY ; AS EXHIBITED IN D03IESTICATED ANIMALS : AS
EXHIBITED IN THE APPEARANCE AND DISAPPEARANCE OF INHERITED
DISEASES; SOMETIMES SUPERVENING EARLIER IN THE CHILD THAN IN
THE PARENT — SUMJIARY OF THE THREE PRECEDING CHAPTERS.

In tlie last two chapters tlie nature and force of Inheritance,
the circumstances which interfere with its power, and the
tendency to Ee version, with its many remarkable contingen-
cies, were discussed. In the present chapter some other
related phenomena will he treated of, as fully as my materials
permit.

Fixedness of Character.

It is a general belief amongst breeders that the longer any
character has been transmitted by a breed, the more fully it
will continue to be transmitted. I do not wish to dispute the
truth of the proposition that inheritance gains strength
simply through long continuance, but I doubt whether it can
be proved. In one sense the proposition is little better than
a truism ; if any character has remained constant during many
generations, it will be likely to continue so, if the conditions
of life remain the same. So, again, in improving a breed, if
care be taken for a length of time to exclude all inferior
individuals, the breed will obviously tend to become truer,
as it will not have been crossed during many generations by
an inferior animal. We have previously seen, but without

24

38 INHEEITANCE. Chap. XIV.

being able to assign any cause, that, when a new character
appears, it is occasionally from the first constant, or fluctuates
much, or wholly fails to be transmitted. So it is with the
ag-OTeerate of slio;ht differences which characterise a new
variety, for some propagate their kind from the first much
truer than others. Even with plants multiplied by bulbs,
layers, &c., which may in one sense be said to form parts of
the same individual, it is well known that certain varieties
retain and transmit through successive bud-generations their
newly-acquired characters more truly than others. In none
of these, nor in the following cases, does there appear to be
any relation between the force with Avhich a character is
transmitted and the length of time during which it has been
transmitted. Some varieties, such as white and yellow hya-
cinths and white sweet-peas, transmit their colours more
faithfully than do the varieties which have retained their
natural colour. In the Irish family, mentioned in the twelfth
chapter, the peculiar tortoiseshell-like colouring of the eyes
was transmitted far more faithfully than any ordinary colour.
Ancon and Mauchamp sheep and niata cattle, which are all
comparatively modern breeds, exhibit remarkably strong
powers of inheritance. Many similar cases could be adduced.
As all domesticated animals and cultivated plants have
varied, and yet are descended from aboriginally wild forms,
which no doubt had retained the same character from an
immensely remote ej)Och, we see that scarcely any degree of
antiquity ensures a character being transmitted perfectly
true. In this case, however, it may be said that changed
conditions of life induce certain modifications, and not that
the power of inheritance fails ; but in every case of failure,
some cause, either internal or external, must interfere. It
will generally be found that the organs or parts which in
our domesticated productions have varied, or which still
continue to vary, — that is, which fail to retain their formei
state, — are the same with the parts which differ in the natural
species of the same genus. As, on the theory of descent with
modification, the species of the same genus have been modified
since the}' branched off from a common progenitor, it follows
that the characters by which they differ from one another

Chap. XIV. FIXEDNESS OF CnAKACTEE. 39

have varied, whilst other parts of the organisation have re-
mained unchanged ; and it might be argued that these same
characters now vary under domestication, or fail to be in-
herited, from their lesser antiquity. But variation in a state
of nature seems to stand in some close relation with changed
conditions of life, and characters which have already varied
under such conditions would be apt to vary under the still
greater changes consequent on domestication, independently
of their greater or less antiquity.

Fixedness of character, or the strength of inheritance, has
often been judged of by the preponderance of certain charac-
ters in the crossed offspring between distinct races ; but
prepotency of transmission here comes into play, and this, as
we shall immediately see, is a very different consideration
from the strength or weal^ness of inheritance.^ It has often
been observed that breeds of animals inhabiting wild and
mountainous countries cannot be permanently modified by
our improved breeds ; and as these latter are of modern
origin, it has been thought that the greater antiquity of the
wilder breeds has been the cause of their resistance to im-
provement by crossing ; but it is more probably due to their
structure and constitution being better adapted to the sur-
rounding conditions. When plants are first subjected to
culture, it has been found that, during several generations,
they transmit their characters truly, that is, do not vary, and
this has been attributed to ancient characters being strongly
inherited : but it may with equal or greater probability be
consequent on changed conditions of life requiring a long
time for their cumulative action. Notwithstanding these
considerations, it would perhaps be rash to deny that charac-
ters become more strongly fixed the longer they are trans-
mitted ; but I believe that the proposition resolves itself into
this, — that characters of all kinds, whether new or old, tend
to be inherited, and that those which have already withstood
all counteracting influences and been truly transmitted, will,
as a general rule, continue to withstand them, and conse-
quently be faithfully inherited.

1 See Touatt on Cattle, pp. 92, 69, p. 325. Also Dr. Lucas, 'L'H^red,
78, 88, 163; and Youatt on Sheep, Nat.,' torn. ii. p. 310.

40 INHERITANCE. Chap. XIV.

Prepotency in the Transmission of Character.

When individuals, belonging to the same family, but
distinct enough to be recognised, or when two well-marked
races, or two species, are crossed, the usual result, as stated
in the previous chapter, is, that the offspring in the first
generation are intermediate between their parents, or resemblG
one parent in one part and the other parent in another part.
But this is by no means the invariable rule ; for in many
cases it is found that certain individuals, races, and species,
are prepotent in transmitting their likeness. This subject
has been ably discussed by Prosper Lucas,^ but is rendered
extremely complex b}^ the prepotency sometimes running
equally in both sexes, and sometimes more strongly in one
sex than in the other ; it is likewise complicated by the
presence of secondary sexual characters, which render the
comparison of crossed breeds with their parents difficult.

It would appear that in certain families some one ancestor,
and after him others in the same family, have had great
power in transmitting their likeness through the male line ;
for we cannot otherwise understand how the same features
should so often be transmitted after marriages with many
females, as in the case of the Austrian Emperors ; and so it was,
according to Niebuhr, with the mental qualities of certain
Eoman families.^ The famous bull Favourite is believed *
to have had a prepotent influence on the short-horn race. It
has also been observed ^ with English race-horses that certain
mares have generall}'- transmitted their own character, whilst
other mares of equally pure blood have allowed the character
of the sire to prevail. A famous black greyhound, Bedlamite,
as I hear from Mr. C. M. Brown "invariably got all his
*' puppies black, no matter what was the colour of the bitch ;"
but then Bedlamite " had a preponderance of black in his
" blood, both on the sire and dam side."

2 'Hered. Nat.,' torn. ii. pp. 112- 270.

120. ^ Mr. N. H. Smith, ' Observations

3 Sir H. Holland, ' Chapters on on Breeding,' quoted in ' Encyclop. of
Mental Physiology,' 1852, p. 234. Rural Sports,' p. 278.

4

' Gardener's Chronicle,' 1860, p.

Chap. XIY. PREPOTENCY OF TEANSMISSION. 41

The trtitli of the principle of prepotency comes ont more clearly
when distinct races are crossed. ' The improved Short-horns, not-
withstanding that the breed is comparatively modern, are generally
acknowledged to possess great power in impressing their likeness
on all other breeds ; and it is chiefly in consequence of this x)ower
that they are so highly valued for exportation.*^ Godine has given
a curions case of a ram of a goat-hke breed of sheep from the Cape
of Good Hope, which lorodnced oflspring hardly to be distingnislied
from himself, when crossed with ewes of twelve other breeds. But
two of these half-bred ewes, when put to a merino ram, x)roduced
lambs closely resembling the merino breed. Girou de Bnzareingnes '^
found that of two races of French sheep the ewes of one, when
crossed during successive generations with merino rams, yielded
up their character far sooner than the ewes of the other race.
Sturm and Girou have given analogous cases with other breeds of
sheep and with cattle, the prepotency running in these cases
through the male side ; but I was assured on good authority in
South America, that when niata cattle are crossed with common
cattle, though the niata breed is prepotent whether males or females
are used, yet that the prepotency is strongest through the female
line. Tlie Manx cat is tailless and has long hind legs ; Dr. "Wilson
crossed a male Manx with common cats, and, out of twenty-three
kittens, seventeen were destitute of tails ; but when the female
Manx was crossed by common male cats all the kittens had tails,
though they were generally short and imperfect.^

In making reciprocal crosses between pouter and fantail pigeons,
the pouter-race seemed to be prepotent through both sexes over
the fantail. But this is probably due to weak power in the fantail
rather than to any unusually strong power in the pouter, for I have
observed that barbs also preponderate over fantails. This weak-
ness of transmission in the fantail, though the breed is an ancient
one, is said ^ to be general ; but I have observed one exception to
the rule, namely, in a cross between a fantail and laugher. The
most curious instance known to me of weak power in both sexes is
in the trumpeter pigeon. This breed has been well known for at
least 130 years: it breeds perfectly true, as I have been assured by
those who have long kept many birds : it is characterised by a
peculiar tuft of feathers over the beak, by a crest on the head, by
a singular coo quite unlike that of any other breed, and by much-
feathered feet. I have crossed both sexes with turbits of two sub-
breeds, with almond tumblers, si3ots, and runts, and reared many
mongrels and recrossed them ; and though the crest on the head

* Quoted by Bronn, ' Gesi hichte p. 112.

der Natur,' b. ii. s. 170. See Sturm, * ]\Ir. Orton, ' Physiology of Breed-

' Lfeber Kacen,' 1825, s. 104-107. ing,' 1855, p. 9.

For the niata cattle, see my ' Journal ^ Boitard and Corbie, 'Les Pigeons,*

of Researches,' 1845, p. 146. 1824, p. 224.

^ Lucas, ' L'Heredite Nat.,' torn. ii.

i2 INHERITANCE. Chap. XIV.

and feathered feet were inherited (as is generally the case with
most breeds), 1 have never seen a vestige of the tuft over the beak
or heard the peculiar coo. Boitard and Corbie '^^ assert that tliis is
the invariable result of crossing trumpeters with other breeds:
Neumeister,^^ however, states that in Germany mongrels have been
obtained, though very rarely, which were furnished with the tuft
and would trumpet: but a pair of these mongrels with a tuft,
which I imported, never trumpeted. Mr. Brent states ^^ that the
crossed offspring of a trumpeter were crossed with trumpeters for
three generations, by which time the mongrels had 7-8ths of this
blood in their veins, yet the tuft over the beak did not appear. At
the fourth generation the tuft appeared, but the birds though now
having 15-16ths trumpeter's blood still did not trumpet. This
case well shows the wide difference between inheritance and pre-
potency ; for here we have a well-established old race Avhich
transmits its characters faithfully, but which, wiien crossed with
any other race, has the feeblest power of trausmittiug its two chief
characteristic qualities.

I will give one other instance with fowls and pigeons of weakness
and strength in the transmission of the same character to their
crossed offspring. The Silk-fowl breeds true, and there is reason
to believe is a very ancient race ; but when I reared a large number
of mongrels from a Silk-hen by a Spanish cock, not one exhibited
even a trace of the so-called silkiness. Mr. Hewitt also asserts that
in no instance are the silky feathers transmitted by this breed when
crossed with any other variety. But three birds out of many raised
by Mr. Orton from a cross between a silk-cock and a bantam-hen
had silky feathers.^^ So that it is certain that this breed very
seldom has the power of transmitting its peculiar plumage to its
crossed progeny. On the other hand, there is a silk sub- variety
of the fantail pigeon, which has its feathers in nearly the same
state as in the Silk-fowl : now we have already seen that fantails,
when crossed, possess singularly weak power in transmitting their
general qualities; but the silk sub- variety when crossed with
any other small-sized race invariably transmits its silky feathers ! ^*

The well-known horticulturist, Mr. Paul, informs me that he
fertilised the Black Prince hollyhock with pollen of the White
Globe and the Lemonade and Black Prince hollyhocks reciprocally;
but not one seedling from these three crosses inherited the black
colour of the Black Prince. So, again, Mr. Laxton, who has had
such great experience in crossing jjeas, writes to me that " when-
" ever a cross has been effected between a white-blossomed and a
" purple-blossomed pea, or between a white-seeded and a purple-
"■ sjiotted, brown or maple-seeded pea, the offspring seems to lose

i<^ ' Les Pigeons,' pp. 168, 198. Mr. Hewitt, in 'The Poultry Book,'

»i 'Das Ganze,' &c., 1837, s. 39. by Tegetmeier, 1866, p. 224.
12 'The Pigeon Book,' p. 46. ''' Boitard and Corbie, 'Les Pigeons,'

i« ' Physiology of Breeding,' p. 22 ; 1824, p. 226.

Chap, XIV.

PREPOTENCY OF TRANSMISSION.

43

" nearly all the characteristics of the ■white-flowered and white-
" seeded varieties ; and this result follows whether these yarieties
" have been iise<:l as the pollen-bearing or seed-producing parents."

The law of prepotency comes into action when species are crossed,
as with races and individuals. Gartner has unequivocally shown ^*
that this is the case with plants. To give one instance: when
JSiicotiana paniciilata and vincoijiora are crossed, the character of
N, paniculata is almost completely lost in the hybrid ; but if N.
quadrivalvis be crossed with N. vincceflora, this latter species,
which was before so prejiotent, now in its turn almost disappears
under the power of A\ quadrivalvis. It is remarkable that the
prepotency of one species over another in transmission is quite in-
dependent, as shown by Gartner, of the greater or less facility with
which the one fertilises the other.

With animals, the jackal is prepotent over the dog, as is stated
by Flourens, who made many crosses between these animals ; and
this was likewise the case with a hybrid which I once saw between
a jackal and a terrier. I cannot doubt, from the observations of
Colin and others, that the ass is prepotent over the horse ; the pre-
potency in this instance running more strongly through the male
than through the female ass ; so that the mule resembles the ass
more closely than does the hinny.'* The male pheasant, judging
from Mr. Hewitt's descriptions,^'^ and from the hybrids which I
have seen, preponderates over the domestic fowl ; but the latter, as
far as colour is concerned, has considerable power of transmission,

^^ ' Basiarderzeugnng,' s. 256, 290,
&c. Kaudin (' Xouvelles Archives du
Museum,' torn. i. p. 149) givfes a
striking instance of prepotency in
Datura stramonium v/hen crossed with
two other species.

*^ Flourens, ' Longevite Humaine,'
p. 144-, on crossed jackals. With
respect to the difference between the
mule and the hiuny, I am aware that
this has generally been attributed to
the sire and dam transmitting their
characters difterently; but Colin,
who has given in his 'Traite Phys.
Comp.,' torn. ii. pp. 537-539, the
fullest description which I have met
with of these reciprocal hybrids, is
strongly of opinion that the ass pre-
ponderates in both crosses, but in an
unequal degree. This is likewise the
conclusioa of Flourens, and of Bech-
6tein in his ' Naturgeschichte Deutsch-
lands,' b. i. s. 294. The tail of the
hinny is much more like that of the
horse than is the tail of the mule.

and this is generally accounted for
by the males of both species trans-
mitting with greater power this part
of their structure ; but a compound
hybrid which I saw in the Zoological
Gardens, from a mare by a hybrid
ass-zebra, closely resembled its mother
in its tail.

*^ Mr. Hewitt, who has had such
great experience in raising these
hybrids, says (' Poultry Book,' by
Mr. Tegetmeier, 1866, pp. 165-167)
that in all, the head was destitute of
wattles, comb, and ear-lappets ; and
all closely resembled the pheasant in
the shape of the tail and general con-
tour of the body. These hybi'ids
were raised from hens of several
breeds by a cock-pheasant ; but
another hj'brid, described by Mr.
Hewitt, was raised from a hen-
pheasant, by a silver-laced Bantam
cock, and this possessed a rudimeutaj
comb and wattles.

i4 INHEEITANCE. Chap. XIV.

for hybrids raised from five diflferently coloured hens differed
greatly in plumage. I formerly examined some curious hybrids in
the Zoological Gardens, between the Penguin variety of the com-
mon duck and the Egyptian goose (Amer cegyptiacus) ; and al-
though I Mali not assert that the domesticated variety prepon-
derated over the natural species, yet it had strongly impressed its
unnatural upright figure on these hybrids.

I am aware that such, cases as the foregoing have been ascribed
by various authors, not to one sjDecies, race, or individual being
prepotent over the other in imjn'essing its character on its crossed
offspring, but to such rules as that the father influences the ex-
ternal characters and the mother the internal or vital organs. But
the great diversity of the rules given by various authors almost
proves their falseness. Dr. Prosper Lucas has fully discussed this
point, and has shown ^* that none of the rules (and I could add
others to those quoted by him) apply to all animals. Similar rules
have been announced for plants, and have been proved by Gartner ^^
to be all erroneous. If we confine our view to the domesticated
races of a single species, or perhaps even to the sjDecies of the same
genus, some such rules may hold good ; for instance, it seems that
in reciprocally crossing various breeds of fowls the male generally
gives colour ; ^*^ but conspicuous exceptions have passed under my
own eyes. It seems that the ram usually gives its peculiar horns
and fleece to its crossed offsi^ring, and the bull the presence or
absence of horns.

In the following chapter on Crossing I shall have occasion to
show that certain characters are rarely or never blended by cross-
ing, but are transmitted in an unmodified state from either parent-
form ; I refer to this fact here because it is sometimes accompanied
on the one side by prepotency, which thus acquires the false
appearance of unusual strength. In the same chapter I shall
show that the rate at which a species or breed absorljs and ob-
literates another by repeated crosses, depends in chief part on
prepotency in transmission.

In conclusion, some of the cases above given, — for instance,
that of the trumpeter pigeon, — prove that there is a wide
difference between mere inheritance and prepotenc}''. This
latter power seems to us, in our ignorance, to act in most cases
quite capriciously. The very same character, even though
it be an abnormal or monstrous one, such as silky feathers,
may be transmitted b}^ different species, when crossed, either
with prepotent force or singular feebleness. It is obvious,

^* ' L'Hered. Nat.,' torn, ii, book ii. Museum/ torn. i. p. 148) has arrived

ch. i. at a similar conclusion.

i» ' Bastarderzeugung,' s. 264-266. ^o < Cottage Gardener,' 1856, pp

Naudin (' Nouvelles Archives du 101, 137.

CiiAP. XiV. PREPOTENCY OF TRANSMISSION. 45

that a purely-bred form of either sex, in all cases in which
prepotency does not run more strongly in one sex than the
other, will transmit its character with prepotent force over
a monoTelised and alreadv variable form.'^^ From several of
the above-given cases we may conclude that mere antiquity
of character does not by any means necessarily make it pre-
potent. In some cases prepotency apjoarently def)ends on the
same character being present and visible in one of the two
breeds which are crossed, and latent or invisible in the other
breed ; and in this case it is natural that the character which
is potentially present in both breeds should be prepotent.
Thus, we have reason to believe that there is a latent ten-
dency in all horses to be dun-coloured and striped ; and
when a horse of this kind is crossed with one of any other
colour, it is said that the offspring are almost sure to be
striped. Sheep have a similar latent tendency to become
dark-coloured, and we have seen with what prepotent force
a ram with a few black spots, when crossed with white sheep
of various breeds, coloured its offspring. All pigeons have a
latent tendency to become slaty-blue, with certain character-
istic marks, and it is known that, when a bird thus coloured
is crossed with one of any other colour, it is most difficult
afterwards to eradicate the blue tint. A nearly parallel case
is offered by those black bantams which, as they grow old,
develope a latent tendency to acquire red feathers. But
there are exceptions to the rule : hornless breeds of cattle
possess a latent capacity to reproduce horns, yet when crossed
with horned breeds they do not invariably produce offspring
bearing horns.

We meet with analogous cases with plants. Striped flowers,
though they can be propagated truly b}' seed, have a latent
tendency to become uniformly coloured, but when once crossed
by a uniformly coloured variety, they ever afterwards fail to

2' See some remarks on this head between English and French sheep,

with respect to sheep by Mr. Wilson, He found that he obtained the

in • Gardener's Chronicle,' 1863, p. 15. desired influence of the English breeds

Many strilcing instances of this result by crossing intentionally mongrelised

are given by M. Malingie-Xouel French breeds with pure English

(' Journ. R. Agricult. Soc.,' vol. xiv. breeds.
1853, p. 220) with respect to crosses

i6 INHERITANCE. Chap. XIV.

produce striped seedliugs.^^ Another case is in some respects
more curious : plants bearing peloric flowers have so strong
a latent tendency to reproduce their normally irregular
flowers, that this often occurs by buds when a plant is trans-
planted into poorer or richer soil.'-^^ Now I crossed the peloric
snapdragon (^Antirrhinum majns), described in the last chapter,
with pollen of the common form ; and the latter, reciprocally,
with peloric pollen. I thus raised two great beds of seed-
lings, and not one was peloric. Xaudin ^^ obtained the same
result from crossing a peloric Linaria with the common form.
I carefully examined the flowers of ninety plants of the
crossed Antirrhinum in the two beds, and their structure had
not been in the least affected by the cross, except that in a
few instances the minute rudiment of the fifth stamen, which
is always present, was more fully or even completely de-
veloped. It must not be supposed that this entire obliteration
of the peloric structure in the crossed plants can be accounted
for by any incapacity of transmission ; for I raised a large
bed of plants from the peloric Antirrhinum, artificially fer-
tilised by its own pollen, and sixteen plants, which alone
survived the winter, were all as perfectly peloric as the
parent-plant. Here we have a good instance of the wide dif-
ference between the inheritance of a character and the power
of transmitting it to crossed offspring. The crossed plants,
which perfectly resembled the common snapdragon, were
allowed to sow themselves, and out of a hundred and twenty-
seven seedlings, eighty-eight proved to be common snap-
dragons, two were in an intermediate condition between the
peloric and normal state, and thirty-seven were perfectl}'-
peloric, having reverted to the structure of their one grand-
parent. This case seems at first sight to offer an exception
to the rule just given, namely, that a character which is
present in one form and latent in the other is generally
transmitted with prepotent force when the two forms are
crossed. For in all the Scrophulariacea3, and especially in
the genera Antirrhinum and Linaria, there is, as was shown

22 Verlot, ' Des Varietes,' 1865, p. Q6.

22 Moquin-Tandon, ' Teratologie,' p. 191.

*■* ' Nouvelles Archives du Museum,' torn i. p. 137.

Chap. XIV. SEXUAL LIMITATION. 47

in the last cliapter, a strong latent tendency to become
peloric; but there is also, as we have seen, a still stronger
tendency in all peloric plants to reacquire their normal
irregular structure. So that we have two opposed latent
tendencies in the same plants. Now, with the crossed
Antirrhinums the tendency to produce normal or irregular
flowers, like those of the common Snapdragon, prevailed in
the first generation ; whilst the tendency to pelorism, ap-
pearing to gain strength by the intermission of a generation,
prevailed to a large extent in the second set of seedlings.
How it is possible for a character to gain strength by the
intermission of a generation, will be considered in the chapter
on pangenesis.

On the whole, the subject of prepotency is extremely intri-
cate, — from its varj^ing so much in strength, even in regard
to the same character, in different animals, — from its runnins:
either equally in both sexes, or, as frequently is the case with
animals, but not witli plants, much stronger in one sex than
the other, — from the existence of secondary sexual charac-
ters, — from the transmission of certain characters beinac
limited, as we shall immediately see, by sex, — from certain
characters not blending together, — and, perhajDS, occasionally
from the effects of a previous fertilisation on the mother.
It is therefore not surprising that no one has hitherto
succeeded in drawing up general rules on the subject of
prepotency.

lalieritance as limited hy Sex.

New characters often appear in one sex, and are afterwards
transmitted to the same sex, either exclusively or in a much
greater degree than to the other. This subject is important,
because with animals of many kinds in a state of nature, both
high and low in the scale, secondary sexual characters, not
directly connected with the organs of reproduction, are con-
spicuously present. With our domesticated animals, characters
of this kind often differ widely from those distinguishing the
two sexes of the parent species ; and the principle of inheri-
tance, as limited by sex, explains how this is possible.

ilr8 INHERITANCE. Chap. XIV.

Dr. P. Liicas has shown "^ tliat when a peculiarity, in no manner
connected with the reproductive organs, appears in either parent,
it is often transmitted exclusively to the offspring of the same sex,
or to a much greater number of them than of the opposite sex.
Thus, in the family of Lambert, the horn-like projections on the
skin were transmitted from the father to his sons and grandsons
alone; so it has been with other cases of ichthyosis, with super-
numerary digits, with a deficiency of digits and phalanges, and in a
lesser degree with various diseases, especially with colour-blindness
and the hsemorrhagic diathesis, that is, an extreme liability to profuse
and uncontrollable bleeding from trifling wounds. On the other
hand, mothers have transmitted, during several generations, to their
daughters alone, supernumerary and deficient digits, colour-blindness
and other peculiarities. So that the very same peculiarity may
become attaced to either sex, and be long inherited by that sex
alone ; but the attachment in certain cases is much more frequent
to one than the other sex. The same peculiarities also may be
promiscuously transmitted to either sex. Dr. Lucas gives other
cases, showing that the male occasionally transmits his peculiarities
to his daughters alone, and the mother to her sons alone ; but even
in this case we see that inheritance is to a certain extent, though
inversely, regulated by sex. Dr. Lucas, after weighing the whole
evidence, comes to the conclusion that every peculiarity tends to
be transmitted in a greater or lesser degree to that sex in which it
first appears. But a more definite rule, as I have elsewhere shown,=^^
generally holds good, namely, that variations which first appear in
either sex at a late period of life, when the reproductive functions
are active, tend to be developed in that sex alone ; whilst variations
which first appear early in life in either sex are commonly trans-
mitted to both sexes. I am, however, far from supposing that this
is the sole deteiinining cause.

A few details from the many cases collected by Mr. Sedgwick,^*"
may be here given. Colour-blindness, from some unknown cause,
shows itself much oftener in males than in females ; in upwards of
two hundred cases collected by Mr. Sedgwick, nine-tenths related
to men ; but it is eminently liable to be transmitted through women.
In the case given by Dr. Earle, members of eight related families
were affected during five generations : these families consisted of
sixty-one individuals, namely, of thirty-two males, of whom nine-
sixteenths were incapable of distinguishing colour, and of twenty-
nine females, of whom only one-fifteenth were thus affected.
Although colour-blindness thus generally clings to the male sex.

2^ ' L'Hered. Nat.,* torn. ii. pp. 137- ^^ On Sexual Limitation in Heredi-

165. /S'^e, also, Mr. Sedgwick's four tary Diseases, ' Biit. an I For. Med. -

memoii-s, immediately to be referred Chirurg. Review,' April 1861, p. 477 ;

io. July, p. 198 ; April 1863, p. 445 ; and

'6 ' Descent of Man,' 2nd edit., p. July, p. 159. Also in 1867, 'On the

32. influence of Age in Hereditai-y Diuease.'

Chap. XIV. SEXUAL LIMITATION. 49

nevertheless, in one instance in wliicli it first appeared in a female,
it was transmitted during five generations to thirteen individuals,
all of whom were females. The hsemorrhagic diathesis, often accom-
panied by rheumatism, has been known to aifect the males alone
during five generations, being transmitted, however, through the
females. It is said that deficient phalanges in the fingers have
been inherited by the females alone during ten generations. In
another case, a man thus deficient in both hands and feet, trans-
mitted the peculiarity to his two sons and one daughter; but in
the third generation, out of nineteen grandchildren, tw^elve sons
had the family defect, whilst the seven daughters were free. In
ordinary cases of sexual limitation, the sons or daughters inherit
the peculiarity, whatever it may be, from their father or mother,
and transmit it to their children of the same sex; but generally
wdth the h?emorrhagic diathesis, and often with colour-blindness,
and in some other cases, the sons never inherit the peculiarity
directly from their fathers, but the daughters alone transmit the
latent tendency, so that the sons of the daughters alone exhibit it.
Thus the father, grandson, and great-great-grandson will exhibit a
I)oculiarity, — the grandmother, daughter, and great-grand -daughter
having transmitted it in a latent state. Hence w^e have, as Mr.
Sedgwick remarks, a double kind of atavism or reversion; each
grandson apparently receiving and developing the peculiarity from
his grandfatlier, and each daughter apparently receiving the latent
tendency from her grandmother.

From the various facts recorded by Dr. Prosper Lucas, My.
Sedgwick, and others, there can be no doubt that peculiarities first
ai^pearing in either sex, though not in any way necessarily or
invariably connected with that sex, strongly tend to be inherited by
the oli'spring of the same sex, but are often transmitted in a latent
state through the opposite sex.

Turning now to domesticated animals, we find that certain
characters not proper to the parent species are often confined to,
and inherited by, one sex alone ; but we do not know the history
of the first appearance of such characters. In the chapter on Sheep,
w^e have seen that the males of certain races differ greatly from
the females in the shape of their horns, these being absent in the
ewes of some breeds ; they diifer also in the development of fat in
the tail and in the outline of the forehead^ These difi"erences,
judging from the character of the allied wild species, cannot be
accounted for by supposing that they have been derived from
distinct parent forms. There is, also, a great difl'erence between
the horns of the two sexes in one Indian breed of goats. The bull
zebu is said to have a larger hump than the cow. In the Scotch
deer-hound the two sexes differ in size more than in any other
variety of the dog,^^ and, judging from analogy, more than in the
aboriginal parent-species. The peculiar colour called tortoiso-

** W. Scrope, ' Art of Deer Stalking,' p. 354.

50 INHERITANCE. Chap. XIV.

shell is very rarely seen in a male cat ; the males of this variety
being of a rusty tint.

In various breeds of the fowl the males and females often differ
greatly ; and these differences are far from being the same with
those which distinguish the two sexes of the parent-species, the
GaUus hanldva ; and consequently have originated under domesti-
cation. In certain sub-varieties of the Game race we have tlie
unusual case of the hens differing from each other more than the
cocks. In an Indian breed of a white colour shaded with black, the
hens invariably have black skins, and their bones are covered by a
black periosteum, whilst the cocks are never or most rarely thus
characterised. Pigeons offer a more interesting case ; for throughout
tlie whole great family the two sexes do not often differ much ; and
the males and females of the parent-form, the G. livia, are undistin-
guishable : yet we have seen that with pouters the male has the
characteristic quality of pouting more strongly developed than the
female; and in certain sub- varieties the males alone are spotted or
striated with black, or otherwise differ in colour. When male and
female English carrier-pigeons are exhibited in separate pens, the
difference in the development of the wattle over the beak and
round the eyes is conspicuous. So that here we have instances of
the appearance, of secondary sexual characters in the domesticated
races of a species in which such differences are naturally quite
absent.

«

On the other hand, secondary sexual characters which
belong to the species in a state of nature are sometimes quite
lost, or greatly diminished, under domestication. AYe see
this in the small size of the tusks in our improved breeds of
the pig, in comparison with those of the wild boar. There
are sub-breeds of fowls, in which the males have lost the fine-
flowing tail-feathers and hackles ; and others in which there
is no difference in colour between the two sexes. In some
cases the barred plumage, which in gallinaceous birds is
commonly the attribute of the hen, has been transferred to
the cock, as in the cuckoo sub-breeds. In other cases mascu-
line characters have been partly transferred to the female, as
with the splendid plumage of the golden-spangled Hamburg
hen, the enlarged comb of the Spanish hen, the pugnacious
disposition of the Game hen, and as in the well-developed
spurs which occasionally appear in the hens of various breeds.
In Polish fowls both sexes are ornamented with a topknot,
that of the male being formed of hackle-like feathers, and
this is a new male character in the genus G alius. On the

Chap. XIV. AT COREESPONDING PERIODS. 51

wliole, as far as I can judge, new characters are more apt
to appear in the males of our domesticated animals than in
the females, ^^ and afterwards to be inherited exclusivelv or
more strongly by the males. Finally, in accordance with
the principle of inheritance as limited by sex, the preserva-
tion and augmentation of secondary sexual characters in
natural species offers no especial difficulty, as this would
follow through that form of selection which I have called
sexual selection.

InJieritance at corresj>ondin(j periods of Life.

This is an important subject. Since the publication of my
' Origin of Species,' I have seen no reason to doubt the truth
of the explanation there given of one of the most remarkable
facts in biology, namely, the difference between the embr^^o
and the adult animal. The explanation is, that variations
do not necessarily or generally occur at a very early period
of embryonic growth, and that such variations are inherited
at a corresponding age. As a consequence of this the embrj^o,
even after the parent-form has undergone great modification,
is left only slightly modified ; and the embryos of widely-
different animals which are descended from a common pro-
genitor remain in manj^ important respects like one another
and probably like their common progenitor. We can thus
understand why embryology throws a flood of light on the
natural system of classification, as this ought to be as far as
possible genealogical. When the embryo leads an inde-
pendent life, that is, becomes a larva, it has to be adapted
to the surrounding conditions in its structure and instincts,
independently of those of its parents; and the principle
of inheritance at corresponding periods of life renders this
possible.

This principle is, indeed, in one way so obvious that it
escapes attention. We possess a number of races of animals
and plants, which, when compared with one another and with

^^ I have given in my ' Descent of usually more variable than the fe*
Man ' (2nd edit. p. 223) sufficient males,
evidence that male animals are

52 INHEElTAi^CE. Chap. XIV.

tlieir parent-forms, present conspicuous differences, both in
their immature and mature states. Look at the seeds of the
several kinds of peas, beans, maize, which can be propagated
truly, and see how they differ in size, colour, and shape,
whilst the full-grown plants differ but little. Cabbages, on
the other hand, differ greatly in foliage and manner of growth,
but hardly at all in their seeds ; and generally it will be
found that the differences between cultivated plants at dif-
ferent periods of growth are not necessarily closely connected
together, for plants may differ much in their seeds and little
when full-grown, and conversely may yield seeds hardly
distinguishable, yet differ much when full-grown. In the
several breeds of poultr}^, descended from a single species,
differences in the eggs and chickens whilst covered with
down, in the plumage at the first and subsequent moults, as
well as in the comb and wattles, are all inherited. With
man peculiarities in the milk and second teeth (of which I
have received the details) are inheritable, and longevity is
often transmitted. So again with our improved breeds of
cattle and sheep, early maturity, including the early develop-
ment of the teeth, and Avith certain breeds of fowl the early
appearance of secondary sexual characters, all come under the
same head of inheritance at corresponding periods.

Numerous analogous facts could be given. The silk-moth,
pei'haps, offers the best instance ; for in the breeds which
ti'ansmit their characters truly, the eggs differ in size, colour,
and shape : the caterpillars differ, in moulting three or four
times, in colour, even in having a dark-coloured mark like
an evebrow, and in the loss of certain instincts : — the cocoons
differ in size, shape, d;nd in the colour and quality of the
silk ; these several differences being followed by slight or
barely distinguishable differences in the mature moth.

But it may be said that, if in the above cases a new pecu-
liarity is inherited, it must be at the corresponding stage of
development ; for an egg or seed can resemble only an egg or
seed, and the horn in a full-grown ox can resemble only a
horn. The following cases show inheritance at corresponding
periods more plainly, because they refer to peculiarities which
might have supervened, as far as we can see, earlier or later

Chap. XIV. A r COltRESPONDING PERIODS. 53

in life, 3'et are inherited at tlie same period at which they
first appeared.

In the Lan]l)ert family the porcnpine-Hke excrescences appeared
in the father and sons at the same age, namely, ahout nine weeks
after birth.^° In the extraordinary hairy family described by Mr.
Crawfurd,^^ children were produced during three generations with
hairy ears ; in the father the hair began to grow over his body at
six years old ; in his daughter somewhat earlier, namely, at one
year ; and in both generations the milk teeth appeared late in life,
the permanent teeth being afterwards singularly deficient. Grey-
ness of hair at an unusually early age has been transmitted in some
families. These cases border on diseases inherited at corresi3onding
periods of life, to which I shall immediately refer.

It is a well known peculiarity with almond-tumbler pigeons, that
the full beauty and peculiar character of the plumage does not
appear until the bird has moulted two or three times. Neumeister
describes and figures a brace of pigeons in which the whole body is
white except the breast, neck, and head; but in their first plumage
all the white feathers have coloured edges. Another breed is more
remarkable : its first plumage is black, with rusty-red wing-bars
and a crescent-shaped mark on the breast ; these marks then
become white, and remain so during three or four moults; but after
this period the white spreads over the body, and the bird loses its
beauty.^^ Prize canary-birds have their wings and tail black :
" this colour, however, is only retained until the first moult, so that
" they must be exhibited ere the change takes place. Once
" moulted, the f)eculiarity has ceased. Of course all the birds
" emanating from this stock have black wings and tails the first
year."^^ A curious and somewhat analogous account has been
given ^ of a family of wild pied rooks which were first observed in
1798, near Chalfont, and which every year from that date up to the
period of the published notice, viz., 1837, " have several of their
" brood particoloured, black and white. This variegation of the
*' plumage, however, disappears with the first moult ; but among
" the next young families there are always a few pied ones."
These changes of plumage, w^hich are inherited at various corre-
sponding periods of life in the pigeon, canary-bird, and rook, are
remarkable, because the parent-species passes through no such
change.

Inherited diseases affe^rd evidence in some respects of less value

30 Prichard, ' Phvs. Hist, of Man- ^- 'Das Ganze der Taubenzucbt,'

kind,' 1851, vol. i. p. 349. 1837, s. 24, tab. iv., tig. 2 ; s. 21, tab.

3' 'Embassy to the Court of Ara,' i., fig. 4.

vol. i. p. 320. The third generation ^^ Kidd's ' Treatise on the Canary,'

is described by Capt. Yule in his p. 18.

' Narrative of the Mission to the ^* Charlesworth, ' Mag. of Nat.

Court of Ava,' 1855, p. 94. Hist.,' vol. i. 1837, p. 167.

54 INHERITANCE. Chap. XIV

than the foregoing cases, because diseases are not necessarily con-
nected with any change in structure ; but in other respects of more
value, because the periods have been more carefully observed.
Certain diseases are communicated to the child apparently by
a j)rocess like inoculation, and the child is from the hrst affected ;
such cases may be here passed over. Large classes of diseases
usually appear at certain ages, such as St. Titus's dance in youth,
consumption in early mid-life, gout later, and apoplexy still later ;
and these are naturally inherited at the same period. But even in
diseases of this class, instances have been recorded, as with St.
Vitus's dance, showing that an unusually early or late tendency to
the disease is inheritable.^^ In most cases the appearance of any
inherited disease is largely determined by certain critical periods
in each person's life, as well as by unfavourable conditions. There
are many other diseases, which are not attached to any particular
period, but which certainly tend to appear in the child at about
the same age at which the i3arent was first attacked. An array of
high authorities, ancient and modern, could be given in support of
this proposition. The illustrious Hunter believed in it; and Piorry"*^
cautions the physician to look closely to the child at the period
when any grave inheritable disease attacked the parent. Dr.
Prosper Lucas;'''^ after collecting facts from every source, asserts
that affections of all kinds, though not related to any particular
period of life, tend to reappear in the offspring at whatever period
of life they first appeared in the progenitor.

As the subject is important, it may be well to give a few
instances, simply as illustrations, not as proof; for jDroof, recourse
must be had to the authorities above quoted. Some of the
following cases have been selected for the sake of showing that, when
a slight departure fi'om the rule occurs, the child is affected some-
what earlier in life than the parent. In the family of Le Compte
blindness was inherited through three generations, and no less
than twenty-seven children and grandcliildren were all affected at
about the same age; their blindness in general began to advance
about the fifteenth or sixteenth year, and ended in total deprivation
of sight at the age of about twenty- two.^^ In another case a father
and his four children all became blind at twenty-one years old ; in
another, a grandmother grew blind at thirty-five, her daughter at
nineteen, and three grandchildren at the ages of thirteen and eleven.^^

^* Dr. Prosper Lucas, ' Hered. Nat.,' children and grandchildren is given

torn. ii. p. 713. as 37 ; but this seems to be an error

^^ ' L'Hered. dans les Maladies,' judging from the paper first published

1840, p. 135. For Hunter, see Har- in the ' Baltimore Med. and Phys.

lan's ' Med. Researches,' p. 530. Reg.' 1809, of which Mr. Sedgwick

^^ ' L'Hered. Nat,,' torn. ii. p. 850. has been so kind as to send me a cop)'.

^^ Sedgwick, ' Brit, and For, Med.- '^ Prosper Lucas, ' Hered. Nat.

Chirurg. Review,' April, 1861, p, 485, torn. i. p. 400.
In some accounts the number of

Chap. XIV. AT COKKESPONDING PEEIODS. 55

So with deafness, two brothers, their father and paternal grand-
father, all became deaf at the age of forty.'*^

Esqnirol gives several striking instances of insanity coming on
at the same age, as that of a grandfather, father, and son, who all
committed suicide near their fiftieth year. Many other cases conld
be given, as of a whole family who became insane at the age of forty. ^^
Other cerebral affections sometimes follow the same rule3 — for
instance, epilepsy and apoplexy. A woman died of the latter
disease when sixty-three years old ; one of her daughters at forty-
three, and the other at sixty-seven : the latter had twelve children,
who all died from tubercular meningitis."^-^ I mention this latter
case because it illustrates a frequent occurrence, namely, a change
in the precise nature of an inherited disease, though still affecting
the same organ.

Asthma has attacked several members of the same family when
forty years old, and other families during infancy. The most
different diseases, such as angina pectoris, stone in the bladder, and
various affections of the skin, have appeared in successive genera-
tions at nearly the same age. The little finger of a man began from
some unknown cause to grow inwards, and the same finger in his
two sons began at the same age to bend inwards in a similar
manner. Strange and inexplicable neuralgic affections have caused
parents and children to suffer agonies at about the same period
of life.^3

I will give only two other cases, which are interesting as
illustrating the disappearance as well as the api3earance of disease
at the same age. Two brothers, their father, their paternal uncles,
seven cousins, and their paternal grandfather, were all similarly
affected by a skin-disease, called pityriasis versicolor ; " the disease,
strictly limited to the males of the family (though transmitted
through the females), usually appeared at puberty, and dis-
appeared at about the age of forty or forty-five years." The second
case is that of four brothers, who when al:fiDut twelve years old
suffered almost every week from severe headaches, which were
relieved only by a recumbent jDOsition in a dark room. Their
father, paternal uncles, paternal grandfather, and granduncles all
suffered in the same way from headaches, which ceased at the age
of fifty-four or fifty-five in all those who lived so long. None of
the females of the family were affected.^^

It is impossible to read the foregoing accounts, and the
many others which have been recorded, of diseases coming

40 Sedgwick, ibid., July, 18G1, p. 1863, p. 449, and July, 1863, p. 162,

202. Dr. J. Steinan, ' Easay on Hereditary

•'^ Piorry, p. 109 ; Prosper Lucas, Disea.se,' 1843, pp. 27, 34.

torn. ii. p. 759. '*•' These cases are given by Mr.

*^ Prosper Lucas, torn. ii. p. 748. Sedgwick, on the authority of Dr. H.

*3 Prosper Lucas, torn. iii. pp. 678, Stewart, in ' Med.-Chirurg. Review,'

700, 702 ; Sedgwick, ibid., April, April, 1863, pp. 449, 477.

56 INHEEITANCE. Chap. XIV.

on during three or even more generations in several members
of the same family at the same age, especially in the case of
rare affections in which the coincidence cannot be attributed
to chance, and to doubt that there is a strong tendency to in-
heritance in disease at corresponding periods of life. When
the rule fails, the disease is apt to come on earlier in the child
than in the parent ; the exceptions in the other direction
being very much rarer. Dr. I^ucas "^^ alludes to several cases
of inherited diseases coming on at an earlier period. I have
already given one striking instance with blindness during
three generations ; and Mr. Bowman remarks that this fre-
quently occurs with cataract. With cancer there seems to be
a peculiar liability to earlier inheritance : Sir J. Paget, who
has particularly attended to this subject, and tabulated a large
number of cases, informs me that he believes that in nine
cases out of ten the later generation suffers from the disease
at an earlier period than the previous generation. He adds,
" In the instances in which the opposite relation holds, and
the members of later generations have cancer at a later age
than their predecessors, I think it will be found that the
non-cancerous parents have lived to extreme old ages." 80
that the longevity of a non-affected parent seems to have the
power of influencing the fatal period in the offspring ; and
we thus apparently get another element of complexity' in
inheritance.

The facts, showing that with certain diseases the period of
inheritance occasionally or even frequently advances, are
important with respect to the general descent-theory, for they
render it probable that the same thing would occur with
ordinary modifications of structure. The final result of a
long series of such advances would be the gradual obliteration
of characters proper to the embrj^o and larva, which would
thus come to resemble more and more closely the mature
parent-form. But any structure which was of service to the
embryo or larva would be preserved by the destruction at
this stage of growth of each individual which manifested
any tendency to lose its proper character at too early an age.

*5 ' Hered. Xat.,' torn. ii. p. 852.

Chap. XIV. SUMMAKY. 57

Finally, from the numerous races of cultivated plants and
domestic animals, in which the seeds or eggs, the yoiing or
old, differ from one another and from those of the parent-
si^ecies : — from the cases in which new characters have ap-
peared at a particular period, and afterwards been inherited
at the same period ; — and from what we know with respect
to disease, we must believe in the truth of the great principle
of inheritance at corresponding periods of life.

Summary of the three preceding Chapters. — Strong as is the
force of inheritance, it allows the incessant appearance of new
characters. These, whether beneficial or injurious, — of the
most trifling importance, such as a shade of colour in a flower,
a coloured lock of hair, or a mere gesture, — or of the highest
importance, as when affecting the brain, or an organ so perfect
and complex as the eye,— or of so grave a nature as to deserve
to be called a monstrosity, — or so peculiar as not to occur
normally in any member of the same natural class, — are often
inherited by man, by the lower animals, and plants. In
numberless cases it suffices for the inheritance of a pecu-
liarity that one parent alone should be thus characterised.
Inequalities in the two sides of the body, though opposed to
the law of symmetr}^, may be transmitted. 'J here is ample
evidence that the effects of mutilations and of accidents, es-
pecially or perhaps exclusively when followed by disease, are
occasionally inherited. There can be no doubt that the evil
effects of the long-continued exposure of the parent to in-
jurious conditions are sometimes transmitted to the offspring.
So it is, as we shall see in a future chapter, with the effects
of the use and disuse of parts, and of mental habits. Periodi-
cal habits are likewise transmitted, but generally, as it would
appear, with little force.

Hence we are led to look at inheiitance as the rule, and
non-inheritance as the anomaly. But this power often ap-
pears to us in our ignorance to act capriciously, transmitting
a character with inexplicable strength or feebleness. The
yerj same peculiarity, as the weeping habit of trees, silky
feathers, d'c, may be inherited either firmly or not at all by
different members of the same group, and even by different

58 INHEKITANCE. Chap. XIV.

individuals of tlie same species, tliougii treated in tlie same
manner. In this latter case we see that the power of trans-
mission is a quality which is merel}^ individual in its attach-
ment. As with single characters, so it is with the several
concurrent slight differences wbich distinguish sub-varieties
or races ; for of these, some can be propagated almost as truly
as species, whiLst others "cannot be relied on. The same rule
holds good with plants, when propagated by bulbs, offsets,
&c., which in one sense still form parts of the same individual,
for some varieties retain or inherit through successive bud-
generations their character far more truly than others.

Some characters not proper to the parent-species have dr-
tainly been inherited from an extremely remote epoch, and
may therefore be considered as firmly fixed. But it is doubt-
ful whether length of inheritance in it^^elf gives fixedness of
character ; though the chances are obviously in favour of any
character which has long been transmitted true or unaltered
still being transmitted true as long as the conditions of life
remain the same. We know that many species, after having
retained the same character for countless ages, whiUt living
under their natural conditions, when domesticated have varied
in the most diversified manner, that is, have failed to transmit
their original form ; so that no character appears to be
absolutel}^ fixed. AVe can sometimes account for the failure
of inheritance by the conditions of life being opposed to the
development of certain characters ; and still oftener, as with
plants cultivated by grafts and buds, by the conditions
causing new and slight modifications incessantly to appear.
In this latter case it is not that inheritance wholly fails, but
that new characters are continually superadded. In some
few cases, in which both parents are similarly characterised,
inheritance seems to gain so much foce by the combined
action of the two parents, that it counteracts its own power,
and a new modification is the result.

In many cases the failure of the parents to transmit their
likeness is due to the breed having bten at some former period
crossed; and the child takes after his grandparent or more
remote ancestor of foreign blood. In other cases, in which
the breed has not been crossed, but some ancient character

Chap. XIV. SUMMARY. 59

has been lost through variation, it occasionally reappears
through reversion, so that the parents apparently fail to
transmit tlieir own likeness. In all cases, however, we may
safely conclude that the child inherits all its characters from
its parents, in whom certain characters are latent, like the
secondary sexual characters of one sex in the other. When,
after a long succession of bud-generatious, a floAver or fruit
becomes separated into distinct segments, having the colours
or other attributes of both parent-forms, we cannot doubt
that these characters were latent in the earlier buds, though
they could not then be detected, or could be detected only in
an intimate] 3^ commingled state. So it is with animals of
crossed jDarentage, w^hich with advancing years occasionally
exhibit characters derived from one of their two parents, of
which not a trace could at first be perceived. Certain mon-
strosities, which resemble what naturalists call the typical
form of the grouj) in question, apparently come under the
same law of reversion. It is assuredly an astonishing fact
that the male and female sexual elements, that buds, and
even full-gro\\Ti animals, should retain characters, dnring
several generations in the case of crossed breeds, and during
thousands of generations in the case of pure breeds, written
as it were in invisible ink, yet read}^ at any time to be evolved
under certain conditions.

What these conditions precisely are, we do not know.
But any cause which disturbs the organisation or constitu-
tion seems to be sufficient. A cross certainly gives a strong
tendency to the reappearance of long-lost characters, borli
corporeal and mental. In the case of plants, this tendency
is much stronger with those species which have been crossed
after long cultivation and which therefore have had their
constitutions disturbed by this cause as well as by cro. sing,
than with species which have always lived under their natural
conditions and have then been crossed. A return, also, of
domesticated animals and cultivated plants to a wild state
favours reversion ; but the tendency under these circumstances
has been much exaggerated.

When individuals of the same family which differ some-
what, and when races or species are crossed, the one is often

60 INHEKITANCE, Chap. XIV.

prepotent over the other in transmitting its character. A
race may possess a strong power of inheritance, and yet when
crossed, as we have seen with trumpeter-pigeons, yield to the
prej)otency of every other race. Prepotency of transmission
may be equal in the two sexes of the same species, but often
runs more strongl}^ in one sex. It plays an important part
in determining the rate at which one race can be modified or
wholly absorbed by repeated crosses with another. We can
seldom tell what makes one race or species prepotent over
another ; but it sometimes depends on the same character
being present and visible in one parent, and latent or poten-
tially jDresent in the other.

Characters may first appear in either sex, but oftener in
the male than in the female, and afterwards be transmitted
to the offspring of the same sex. In this case we may feel
confident that the peculiarity in question is really present
though latent in the opposite sex ! hence the father may
transmit through his daughter any character to his grandson ;
and the mother conversely to her granddaughter. We thus
learn, and the fact is an important one, that transmission and
development are distinct powers. Occasionally these two
powers seem to be antagonistic, or incapable of combination
in the same individual ; for several cases have been recorded
in which the son has not directly inherited a character from
his father, or directly transmitted it to his son, but has
received it by transmission through his non-affected mother,
and transmitted it through his non-affected daughter. Owing
to inheritance being limited by sex, we see how secondary
sexual characters may have arisen under nature ; their
preservation and accumulation being dependent on their
service to either sex.

At whatever period of life a new character first appears, it
generally remains latent in the offspring until a corresponding
age is attained, and then is developed. When this rule fails,
the child generally exhibits the character at an earlier period
than the parent. On this principle of inheritance at corre-
sponding periods, we can understand how it is that most
animals display from the germ to maturity such a marvellous
succession of characters.

Chap. XIY. SUMMAEY. 61

Finally, tlioiigli much remains obscure with respect to In-
heritance, we may look at the following laws as fairly well
established. Firstly, a tendency in every character, new and
old, to be transmitted by seminal and bud generation, though
often counteracted by various known and unknown causes.
Secondly, reversion or atavism, which depends on transmis-
sion and development being distinct powers : it acts in
various degrees and manners through both seminal and bud
generation. Thirdly, prepotency of transmission, which
may be confined to one sex, or be common to both sexes.
Fourthly, transmission, as limited by sex, generally to the
same sex in which the inherited character first appeared ;
and this in many, probably most cases, depends on the
new character having first appeared at a rather late period
of life. Fifthly, inheritance at corresponding periods of life,
wdth some tendency to the earlier development of the
inherited character. In these laws of Inheritance, as dis-
played under domestication, we see an ample provision for
the production, through variability and natural selection, of
new specific forms.

25

62 ON CKOSSING AS A CAUSE. Chap. XV.

CHAPTER XV.

ON CEOSSING.

FREE INTERCROSSING OBLITERATES THE DIFFERENCES BETWEEN ALLIED
BREEDS— WHEN THE NUMBERS OP TWO COMMINGLING BREEDS ARE
UNEQUAL, ONE ABSORBS THE OTHER — THE RATE OF ABSORPTION DETER-
MINED BY PREPOTENCY OF TRANSMISSION, BY THE CONDITIONS OF LIFE,
AND BY NATURAL SELECTION — ALL ORGANIC BEINGS OCCASIONALLY INTER-
CROSS ; APPARENT EXCEPTIONS — ON CERTAIN CHARACTERS INCAPABLE OF
FUSION ; CHIETLY OR EXCLUSIVELY THOSE WHICH HAVE SUDDENLY
APPEARED IN THE INDIVIDUAL — ON THE MODIFICATION OF OLD RACES, AND

THE FORMATION OF NEW RACES, BY CROSSING SOME CROSSED RACES

HAVE BRED TRUE FROM THEIR FIRST PRODUCTION — ON THE CROSSING OF
DISTINCT SPECIES IN RELATION TO THE FORMATION OF DOMESTIC
RACES.

In the two previous chapters, when discussing reversion and
prepotency, I was necessarily led to give many facts on
crossing. In the present chapter I shall consider the part
which crossing plays in two opposed directions, — firstly, in
obliterating characters, and consequently in preventing the
formation of new races ; and secondly, in the modification of
old races, or in the formation of new and intermediate races,
by a combination of characters. I shall also show that certain
characters are incapable of fusion.

The effects of free or uncontrolled breeding between the
members of the same variety or of closely allied varieties are
important ; but are so obvious that they need not be dis-
cussed at much length. It is free intercrossing which chiefly
gives uniformity, both under nature and under domestication,
to the individuals of the same species or variety, Avhen they
live mingled together and are not exposed to any cause
inducing excessive variability. The prevention of free cross-
ing, and the intentional matching of individual animals, are
the corner-stones of the breeder's art. Ko man in his senses
would *ixpect to improve or modify a breed in any particular
manner, or keep an old breed true and distinct, unless he

Chap. XV. OF UNIFOKMITY OF CHARACTER. 63

separated his animals. The killing of inferior animals in
each generation comes to the same thing as their separation.
In savage and semi-civilised countries, where the inhabitants
have not the means of separating their animals, more than
a single breed of the same species rarely or never exists. In
former times, even in the United states, there were no distinct
races of sheep, for all had been mingled together.^ The cele-
brated agriculturist Marshall '^ remarks that " sheep that
*' are kept within fences, as well as shepherded flocks in open
" countries, have generally a similarity, if not a uniformity,
" of character in the individuals of each flock ;" for they
breed freely together, and are prevented from crossing with
other kinds; whereas in the unenclosed parts of England
the unshepherded sheep, even of the same flock, are far from
true or uniform, owing to various breeds having mingled
and crossed. We have seen that the half-wild cattle in
each of the several British parks are nearly uniform in cha-
racter ; but in the different parks, from not having mingled
and crossed during many generations, they differ to a
certain small extent.

We cannot doubt that the extraordinary number of varieties
and sub-varieties of the pigeon, amounting to at least one
hundred and fifty, is partly due to their remaining, dif-
ferently from other domesticated birds, paired for life once
matched. On the other hand, breeds of cats imjDorted into
this country soon disappear, for their nocturnal and rambling
habits render it hardly possible to prevent free crossing.
Eengger^ gives an interesting case with respect to the cat
in Paraguay : in all the distant parts of the kingdom it has
assumed, apparently from the effects of the climate, a peculiar
character, but near the capital this change has been pre-
vented, owing, as he asserts, to the native animal frequently
crossing with cats imported from Europe. In all cases like
the foregoing, the effects of an occasional cross will be aug-
mented by the increased vigour and fertility of the crossed
offsjDring, of which fact evidence will hereafter be given ; for

^ 'Communications to the Board of England,' 1808, p. 200.
Agriculture,' vol. i. p. 367. ^ ' Saugethiere von Paraguay.

2 ' Review of Reports, North of 1830, s. 2l2.

61 ON CEOSSING AS A CAUSE. ChaP. XV.

tliis will lead to the mongrels increasing more rapidly than
the pure parent-breeds.

When iistinct breeds are allowed to cross freely, the result
will be a heterogeneous body ; for instance, the dogs in Para-
guay are far from uniform, and can no longer be affiliated to
their parent -races.* The character which, a crossed body of
animals will ultimately assume must depend on several con-
tingencies, — namely, on the relative members of the individuals
belonging to the two or more races which are allowed to
mingle ; on the prepotency of one race over the other in the
transmission of character; and on the conditions of life to
which they are exposed. AVhen two commingled breeds exist
at first in nearly equal numbers, the whole will sooner or
later become intimately blended, but not so soon, both breeds
being equally favoured in all respects, as might have been
expected. The following calculation ^ shows that this is the
case : if a colony with an equal number of black and white
men were founded, and we assume that they marry indis-
criminately, are equally prolific, and that one in thirty
annually dies and is born ; then " in 65 years the number of
" blacks, whites, and mulattoes would be equal. In 91 years
" the whites would be 1-lOth, the blacks 1-1 0th, and the
*' mulattoes, or people of intermediate degrees of colour,
" 8-lOths of the whole number. In three centuries not
" l-lOOth part of the whites would exist."

When one of two mingled races exceed the other greatly
in number, the latter will soon be wholly, or almost wholly,
absorbed and lost.® Thus European pigs and dogs have been
largely introduced in the islands of the Pacific Ocean, and
the native races have been absorbed and lost in the course of
about fifty or sixty years ; ^ but the imported races no doubt
were favoured. Eats may be considered as semi-domesticated
animals. Some snake-rats (^Mus alexandrinus) escaped in the
Zoological Gardens of London, " and for a long time after-

* Rengger, ' Siiugethiere,' &c., s. maines,' p. 24, first called attention
154. to this subject, and ably discussed it.

* White, ' Regular Gradation in ^ Rev. D. Tyerman and Bennett,
Man,' p. 146. ' Journal of Voyages,' 1821-1829, vol.

8 Dr. W. F. Edwards, in his ' Ca- i. p. 300.
ract6res Physiolog. des Races Hu-

Chap. XV. OF UNIFOKMITY OF CHARACTEK. 65

" wards the keepers frequently caught cross-bred rats, at
" first half-breds, afterwards with less of the character of the
*' snake-rat, till at length all traces of it disappeared.^ On
the other hand, in some parts of London, especially near the
docks, where fresh rats are frequently imported, an endless
variety of intermediate forms may be found between the
brown, black, and snake rat, which are all three usually
ranked as distinct species.

How many generations are necessary for one species or race
to absorb another by repeated crosses has often been dis-
cussed;^ and the requisite number has probably been much
exao-orerated. Some writers have maintained that a dozen
or score, or even more generations, are necessary ; but this in
itself is improbable, for in the tenth generation there would
be only 1-1 024th part of foreign blood in the offspring.
Gartner found,^° that with plants, one species could be made
to absorb another in from three to five generations, and he
believes that this could always be effected in from six to
seven generations. In one instance, however, Kolreuter ^^
speaks of the offspring of Mirahilis vulgaris^ crossed during
eight successive generations by M. lonr/ijiora, as resembling
this latter species so closely, that the most scrupulous
observer could detect " vix aliquam notabilem differentiam "
or, as he says, he succeeded, " ad plenariam fere transmnta-
tionem." But this expression shows that the act of absorp-
tion was not even then absolutely complete, though these
crossed plants contained only the 1-2 5 6th part of M. vulgaris.
The conclusions of such accurate observers as Gartner and
Kolreuter are of far higher worth than those made without
scientific aim by breeders. The most precise account which
I have met with is given by Stonehenge,^^ and is illustrated
by photographs. Mr. Hanley crossed a. greyhound bitch with
a bulldog ; the offspring in each succeeding generation being
recrossed with first-rate grej-hounds. As Stonehenge remarks,

^ Mr. S. J. Salter, ' Journal Liua. crosses. Dr. P. Lucas, ' L'Hereditd

Soc.,' vo.. vi., 18(J2, p. 71. Xat.,' torn. ii. p. 308.

9 Sturm, 'Ueber Racen, &c.,' 1825, i" ' Bastarderzeugung,' s. 463, 470.

s. 107. Bronn, ' Geschichte der Na- '^ ' Nova Acta Petrop.,' 1794, p.

tur,' b. ii. s. 170, gives a table of the 393 : see also previous volume,

proportions of blood after successive '^ ' The Dog,' 1867, pp. 179-184.

66 ON CROSSING AS A CAUSE Chap. XV

It might naturally be supposed tliat it would take several
orosR-es to get rid of the heavy form of the bulldog; but
Hysteriob, tlie gr-gr-granddaughter of a bulldog, showed no
trace whatever of this breed in external form. She and all
of the same litter, however, were " remarkably deficient in
" stoutness, thousrh fast as well as clever." I believe clever
refers to skill in turning. Hysterics was jiut to a son of
Bedlamite, " but the result of the fifth cross is not as yet, I
" believe, more satisfactory than that of .the fourth." On the
other hand, with sheep, Fleischmann ^^ shows how persistent
the effects of a single cross may be : he says " that the original
" coarse sheep (of Germany) have 5500 fibres of wool on a
" square inch ; grades of the third or fourth Merino cross
" produced about hOOO, the twentieth cioss 27,000, the per-
*' feet pure Merino blood 40,000 to 48,000." So that common
German sheep crossed twenty times successively with Merino
did not by any menns acquire avooI as fine as that of the pure
breed. But in all cases, the rate of absorption will depend
largely on the conditions of life being favourable to any
particular character ; and we may suspect that there would
be a constant tendency to degeneration in the wool of Merinos
under the climate of Germany, unless prevented by careful
selection; and thus perhaps ike foregoing remarkable case
may be explained. The rate of absorption must also depend
on the amount of distinguishable difference between the two
forms which are crossed, and especially, as Gartner insists, on
prepotency of transmission in lUe one form over the other.
We have seen in the last cnapter that one of two French
breeds of sheep yielded up its character, when crossed with
Merinos, very much more slowly than the other ; and the
common German sheep referred to by Fleischmann may be in
this respect analogous. In all cases there will be more or less
liability to reversion during man}'' subsequent generations,
and it is this fact which has probably led authors to maintain
that a score or more of generations are requisite for one race
to absorb another. In considering the final result of the
commingling of two or more breeds, we must not forget that

" As quoted in the * True Principles of Breeding,' by C. H. Macknight
and Dr. H. Madden, 1865, p. 11.

Chap. XV. oF UNIFORMITY OF CHAKACTER. 67

«

the act of c]'0>sin<2: in itself tends to brins; back lono;-los1
characters not proper to the immediate parent-forms.

With respect to the influence of the conditions of life on
any two breeds which are allowed to cross freely, unless both
are indigenous and have long been accustomed to the country
where they live, they will, in all probability, be unequally
affected by the conditions, and this will modify the result.
Even with indigenous breeds, it will rarely or never occur
that both are equally well adapted to the surrounding cir-
cumstances ; more especially when permitted., to roam freely,
and not carefully tended, as is generally the case with breeds
allowed to cross. As a consequence of this, natural selection
will to a certain extent come into action, and the best fitted
will survive, and this will aid in determining the ultimate
character of the commingled body.

How long a time it w^ould require before such a crossed body
of animals would assume a uniform character within a limited
area, no one can say ; that they would ultimately become
uniform from free intercrossing, and from the survival of the
fittest, we may feel assured ; but the characters thus acquired
would rarely or never, as may be inferred from the previous
considerations, be exactly intermediate between those of the
two 23arent-breeds. With respect to the very slight differences
by which the individuals of the same sub-variety, or even of
allied varieties, are characterised, it is obvious that free
crossing would soon obliterate such small distinctions. The
formation of new varieties, independently of selection, would
also thus be prevented ; except when the same variation
continually recurred from the action of some strongly pre-
disposing cause. We may therefore conclude that free
crossing has in all cases played an important part in giving
uniformity of character to all the members of the same
domestic race and of the same natural species, though largely
governed by natural selection and b^^ the direct action of the
surrounding conditions.

On the ijossihility of all organic hcings occasionally infer'crossing.
— But it may be asked, can free crossing occur with herma-
phrodite animals and plants ? All the higher animals, and
the few insects which have lieen domesticated, have separate

68 ON ALL OKGANIC BEINGS Chap. XY.

gexes, and must inevitably unite for each birth. With respect
to the crossing of hermaphrodites, the subject is too large for
the present volume, but in the ' Origin of Species,' I have
given a short abstract of the reasons which induce me to
believe that all organic beings occasionally cross, though
perhaps in some cases onl}^ at long intervals of time.^* I
will merely recall the fact that many plants, though herma-
phrodite in structure, are unisexual in function ; — such as
those called by C. K. Sprengel dichogamotis, in which the
pollen and stigma of the same flower are matured at different
periods ; or those called by me reciprocally dimorphic, in which
the flower's own pollen is not fitted to fertilise its own
stigma ; or again, the many kinds in which curious mechani-
cal contrivances exist, eflectually preventing self-fertilisation.
There are, however, many hermaphrodite plants wnich are not
in any way specially constructed to favour intercrossing, but
which nevertheless commingle almost as freely as animals
with separated sexes. This is the . case with cabbages,
radishes, and onions, as I know from having experimented on
them : even the peasants of Liguria say that cabbages must
be prevented " from falling in love " with each other. In
the orange tribe, Gallesio^^ remarks that the amelioration of
the various kinds is checked by their continual and almost
regular crossing. So it is with numerous other plants.

On the other hand, some cultivated plants rarely or never
intercross, for instance, the common pea and sweet-pea
{Latliyrus odoratus); yet their flowers are certainly adapted
for cross fertilisation. The varieties of the tomato and
aubergine {Solanura) and the pimenta (Pimenla vulgaris?)
are said^^ never to cross, even when growing alongside one
another. But it should be observed that these are all exotic
plants, and we do not know how they would behave in their
native country when visited by the proper insects. With

^* With respect to plants, an admir- appeared on the same subject, more

able essay on this subject (Die Gesch- especially by Hermann Miiller and

lechter-V'ertheilung bei den Pflanzen : Delpino.

1867) has been published by Dr. Hil- *^ ' Teoria della Riproduzione Vege-

debrand, who arrives at the same tal,' 1816, p. 12.

general conclusions as I have done. '* Verlot, ' Des Varietes,' 1865, p.

Various other treatises have since 72.

Chap. XV. OCCASIONALLY INTERCROSSING. G9

respect to the common pea, I have ascertained that it is
rarely crossed in this conntr}'' owing to premature fertilis-
ation. There exist, however, some plants which under their
natural conditions ap})ear to be always self-fertili^jed, buch as
the Bee Ophrys {Ophrys apifera) 2indi a few other Orchids;
yet these plants exhibit the plainest adaptations for cross-
fertilisation. Again, some few plants are believed to produce
only closed flowers, called cleistogene, which cannot j)ossibly
be crossed. This was long thought to be the case with the
Leersia oryzoides,^'^ but this grass is now known occasionally
to produce perfect flowers, which set seed.

Although some plants, both indigenous and naturalised,
rarely or never produce flowers, or if they flower never
produce seeds, yet no one doubts that phanerogamic plants
are adapted to produce flowers, and the flowers to produce
seed. When the}'' fail, we believe that such plants under
different conditions would perform their proper function, or
that they formerly did so, and will do so again. On analo-
gous grounds, I believe that the flowers in the above specified
anomalous cases which do not now intercross, either would
do so occasionally under different conditions, or that they
formerly did so — the means for affecting this being generally
still retained — and will again intercross at some future
period, unless indeed they become extinct. On this view
alone, many points in the structure and action of the repro-
ductive organs in hermaphrodite plants and animals are in-
telligible, — for instance, the fact of the male and female organs
never being so completely enclosed as to render access from
without impossible. Hence we may conclude that the most
important of all the means for giving uniformity to the in-
dividuals of the same species, namely, the capacity of oc-
casionally intercrossing, is present, or has been formerly
present, with all organic beings, except, perhaps, some of
the lowest.

On certain Characters not blending. — When two breeds are crossed
their characters usually become intimately fused together; but

" Duval Jouve, ' Bull. Soc. Bnt. setting seed, see Dr. Ascherson in ' Bot.
de France,' torn, x., 1863, p. 194. Zeitung,' 1864, p. 350.
With respect to the perfect flowers

70

ON CERTAIN CHARACTERS

Chap. XV

some characters refuse to blend, and are transmitted in an nn-
modified state either from both parents or from one. When grey
and white mice are paired, the young are piebald, or pure white or
grey, but not of an intermediate tint; so it is when white and
common collared turtle-doves are paired. In breeding Game fowls,
a great authority, Mr. J. Douglas, remarks, " I may here state a
" strange fact : if you cross a black with a white game, you get
" birds of both breeds of the clearest colour." Sir R. Heron crossed
during many years white, black, brown, and fiiwn-coloured Angora
rabbits, and never once got these colours mingled in the same
animal, but often all four colours in the same litter.^** From cases like
these, in which the colours of the two parents are transmitted quite
separately to the offspring, we have all sorts of gradations, leading
to complete fusion. I will give an instance : a gentleman with a
fair complexion, light hair but dark eyes, married a lady with dark
hair and complexion : their three children have very light hair, but
on careful search about a dozen black hairs were found scattered in
the midst of the light hair on the heads of all three.

When turnspit dogs and ancon sheep, both of which have dwarfed
limbs, are crossed ^yith common breeds, the offspring are not inter-
mediate in structure, but take after either parent. When tailless or
hornless animals are crossed with perfect animals, it frequently, but
by no means invariably, happens that the offspring are either
furnished with these organs in a perfect state, or are quite destitute
of them. According to liengger, the hairless condition of the
Paraguay dog is either perfectly or not at all transmitted to its
mongrel offspring; but I have seen one partial exception in a dog
of this parentage which had part of its skin hairy, and part naked,
the parts being distinctly separated as in a piebald animal. When
Dorking fowls with five toes are crossed with other breeds, the
chickens often have five toes on one foot and four on the other.
Some crossed pigs raised by Sir E. Heron between the solid-hoofed
and common pig had not all four feet in an intermediate condition,
but two feet were furnished with properly divided, and two with
■united hoofs.

Analogous facts have been observed with plants : Major Trevor

** Extract of a letter from Sir R.
Heron, 1838, given me bj Mr. Yarrell.
With respect to mice, ste ' Annal. des
Sc. Nat.,' torn. i. p. 180; and I have
heard of other similar ca'^es. For
turtle-doves, Boitard and Corbie, ' Les
Pigeons,' &c., p. 238. For the Game
fowl, 'The Poultry Book,' 1866, p.
128. For crosses of tailless fowls,
see Bejhstein, 'Naturge-. Deutsch.'
b. iii. s. 403. Bronn, ' Geschichte
der Natur,' b. ii. s. 170, gires analo-
gous facts with horses. On the hair-

less condition of crossed South Ameri-
can dogs, see Hengger, ' Saugethiere
von Paraguay,' s. 152 : but I saw in
the Zoological Gardens mongrels,
from a similar cross, which were
hairless, quite hairy, or hairy in
patches, that is, piebald with hair.
For crosses of Dorking and other
fowls, see ' Poultry Chronicle,' vol. ii.
p. 355. About the crossed pigs, ex-
tract of letter from Sir R. Heron to
Mr. Yarrell. For other cases, see P.
Lucas, ' L'Hered. Nat.' torn. i. p. 212.

Chap. XV. NOT BLENDING. 71

Clarke crossed the little^ glabrous-leaved, annual stock (Math tola),
with pollen of a large, red- flowered, rough-leaved, biennial stock,
called cocardeau by the French, and the result was that half the
seedlings had glabrous and the other half rough leaves, but none
had leaves in an intermediate state. That the glabrous seedlings
were the product of the rough-leaved variety, and not accidentally
of the mother-plant's own pollen, was shown by their tall and
strong habit of growth.^^ In the succeeding generations raised
from the rough-leaved crossed seedlings, some glabrous plants
appeared, showing that the glabrous character, though incapable
of blending with and modifying the rough leaves, was all the time
latent in this family of plants. The numerous plants formerly
referred to, which I raised from reciprocal crosses between the
peloric and common Antirrhinum, offer a nearly parallel case ; for
in the first generation all the plants resembled the common form,
and in the next generation, out of one hundi'ed and thirty-seven
plants, two alone were in an intermediate condition, the others
perfectly resembling either the peloric or common form. Major
Trevor Clarke also fertilised the above-mentioned red-flowered
stock with pollen from the purple Queen stock, and about half the
seedlings scarcely differed in habit, and not at all in the red colour of
the flower, from the mother-plant, the other half bearing blossoms
of a rich pnrple, closely like those of the paternal plant. Gartner
crossed many white and yellow-flowered species and varieties of
Yerbascum; and these colours were never blended, but the off-
spring bore either pure white or pure yellow blossoms ; the former
in the larger proportion.'^" Dr. Herbert raised many seedlings, as
he informed me, from Swedish turnips crossed by two other
varieties, and these never produced flowers of an intermediate tint,
but always like one of their parents. I fertilised the purple sweet-
pea (Lat/iyrifs odoratus), which has a dark reddish-pm-ple standard-
petal and violet-coloured wings and keel, with pollen of the painted
lady sweet-pea, which has a pale cherry-coloured standard, and
almost white wings and keel ; and from the same pod I twice
raised plants perfectly resembling both sorts ; the greater number
resembling the father. So perfect was the resemblance, that I
should have thought there had been some mistake, if the plants
which were at first identical with the paternal variety, namely, the
painted-lady, had not later in the season produced, as mentioned in
a former chapter, flowers blotched and streaked with dark purple.
I raised grandchildren and great-grandchildren from these crossed
plants, and they continued to resemble the painted-lady, but
during later generations became rather more blotched with purple,
yet none reverted comj^letely to the original mother-plant, the purple

" * Internat. Hort. and Bot. Con- diate tints from similar crosses in the

grass of London,' 18G6. genus Verbascum. With respect to

2° ' Bastarderzeugung,' s. 307. the turnips, see Herbert's ' Amarylli-

Kolreuter ('Dritte Fortsetszung,' s. daceas,' 1837, p. 370.
34, 39), however, obtained interme-

72 ON CERTAIN CHARACTERS NOT BLENDING. Chap. XV.

sweet-pea. The following case is slightly different, but still shows the
same principle : Naudin'^^ raised numerous hybrids between the
yellow Linaria vulgaris and the purple L. purpurea, and during
three successive generations the colours kept distinct in different
parts of the same flower.

From cases such as the foregoing, in which the offspring of the first
generation perfectly resemble either parent, we come by a small
step to those cases in which differently coloured flowers borne on
the same root resemble both parents, and by another step to those
in which the same flower or fruit is striped or blotched with
the two parental colours, or bears a single stripe of the colour or
other characteristic quality of one of the parent-forms. With hybrids
and mongrels it frequently or even generally happens that one part
of the body resembles more or less closely one parent and another
part the other parent ; and here again some resistence to fusion, or,
what comes to the same thing, some mutual affinity between the
organic atoms of the same nature, apparently comes into play, for
otherwise all parts of the body would be equally intermediate in
character. So again, when the offspring of hybrids or mongrels,
which are themselves nearly intermediate in character, revert either
wholly or by segments to their ancestors, the principle of the
affinity of similar, or the repulsion of dissimilar atoms, must come
into action. To this principle, which seems to be extremely general,
we shall recur in the chapter on pangenesis.

It is remarkable, as has been strongly insisted upon by Isidore
Geoflfroy St. Hilaire in regard to animals, that the transmission of
characters without fusion occurs very rarely when species are
crossed ; I know of one exception alone, namely, with the liybrids
naturally produced between the common and hooded crow (Corvus
corone and comix), which, however, are closely allied species,
differing in nothing except colour. Nor have I met with any well-
ascertained cases of transmission of this kind, even when one form
is strongly prepotent over another, when two races are crossed
which have been slowly formed by man's selection, and therefore
resemble to a certain extent natural species. Such cases as puppies
in the same litter closely resembling two distinct breeds, are
probably due to snperfoetation, — that is, to the influence of two
fathers. All the characters above enumerated, which are trans-
mitted in a perfect state to some of the offspring and not to others,
— such as distinct colours, nakedness of skin, smoothness of leaves,
absence of horns or tail, additional toes, pelorism, dwarfed structure,
&c., — have all been known to appear suddenly in individual animals
and plants. From this fact, and from the several slight, aggregated
diiferences which distinguish domestic races and species from one
another, not being liable to this peculiar form of transmission, we
may conclude that it is in some way connected with the sudden
appearance of the characters in question.

2' * NouTclles Archives du Museum,' torn. i. p. 100,

Chap. XV. CROSSING AS MODIFYING RACES. 73

On tlie Modification of old Races and the Furmation of new
"Races hy Crossing. — We have hitherto chiefly considered the
effects of crossing in giving uniformity of character ; we
must now look to an opposite result. There can be no doubt
that crossing, with the aid of rigorous selection during
several generations, has been a potent means in modifying
old races, and in forming new ones. Lord Orford crossed his
famous stud of greyhounds once with the bulldog, in order to
give them courage and perseverance. Certain pointers have
been crossed, as I hear from the Rev. AV. D. Fox, with the
foxhound, to give them dash and speed. Certain strains of
Dorking fowls have had a slight infusion of Game blood ;
and I have known a great fancier who on a single occasion
crossed his turbit-pigeons with barbs, for the sake of gaining
greater breadth of beak.

In the foregoing cases breeds have been crossed once, for
the sake of modifying some particular character ; but with
most of the improved races of the pig, which now breed true,
there have been repeated crosses, — for instance, the improved
Essex owes its excellence to repeated crosses with the Neapo-
litan, together probably with some infusion of Chinese blood. ^^
So with our British sheep : almost all the races, except the
Southdown, have been largely crossed; "this, in fact, has
been the history of our principal breeds." '^^ To give an
example, the " Oxfordshire Downs " now rank as an estab-
lished breed.-^ They were produced about the year 1830 by
crossing "Hampshire and in some instances Southdown ewes
with Cotswold rams : " now the Hampshire ram was itself
produced by repeated crosses between the native Hampshire
sheep and Southdowns ; and the long-woolled Cotswold were
improved by crosses with the Leicester, which latter again is
believed to have been a cross between several long-woolled
Bheep. Mr. Spooner, after considering the various cases

" Richardson, ' Pigs,' 184-7. pp. 37, part ii. : see also an equally good

4-2 ; S. Sidney's edition of ' Youatt on article by Mr. Ch. Howard, in ' Gar-

the Pig,' 1860, p. 3. dener's Chronicle,' 1860, p. 320.

" Seellv. W. C. Spooner's excel- 2* ' Gardener's Chronicle,' 1857, pp.

lent paper on Cross-Breeding, ' Jour- 649, 652.
ual Koyal Agricult. Soc.,' vol. xx..

74 ON CROSSING AS A CAUSE Chap. XV

wliich. h-ive been carefully recorded, concludes, " that from a
judicious pairing of cross-bred animals it is practicable to
establish a new breed." On the continent the history of
several crossed races of cattle and of other animals has been
well ascertained. To give one instance : the King of Wurtem-
burg, after twenty-five years' careful breeding, that is, after
six or seven generations, made a new breed of cattle from a
cross between a Dutch and a Swiss breed, combined with other
breeds.^^ The Sebright bantam, which breeds as true as any
other kind of fowl, was formed about sixty years ago by a
complicated croi^s.-*^ Dark Brahmas, which are believed by
Fome fanciers to constitute a distinct species, were un-
doubtedly formed'-^^ in the United States, within a recent
period, by a cross between Chittagongs and Cochins. With
plants there is little doubt that the Swede-turnip originated
from a cross ; and the history of a variet}"- of wheat, raised
from two very distinct varieties, and which after six years'
culture presented an even yample, has been recorded on good
authority. 2^

Until lately, cautious and experienced breeders, though
not averse to a single infusion of foreign blood, were al-
most universally convinced that the attempt to establish a
new race, intermediate between two widely distinpt races,
was hopeless : " they clung with superstitious tenacit}^ to the
" doctrine of purity of blood, believing it to be the ark in
" which alone true safety could be found." ^^ Nor was this
conviction unreasonable : when two distinct races are crossed,
the offspring of the first generation are generally nearly uni-
form in character ; but even this sometimes fails to be the
case, especially with crossed dogs and fowls, the young of
which from the fi.rst are sometimes much diversified. As
cross bred animals are generally of large size and vigorous,
they have been raised in great numbers for immediate con-
sumption. But for breeding they are found utterly useless ;

" ' Bulletin de la Soc. d'Acclimat.,' " ' The Poultry Book,' by W. B.

1862, torn. ix. p. 463. See also, for Tegetmeier, 1866, p. 58.
other cases, MM. Moll and Gayot, "* 'Gardener's Chronicle,' 1852,

' Du Boeuf,' 1860, p. xxxii. p. 765.

2^ ' Poultry Chvonicle,'' vol. ii., "^ Spooner, in ' Journal Royal Agri-

1854, p. 36. cult. Sue.,' vol. xx., part ii.

Chap. XV. OF THE MODIFICATION OF RACES. 75

for tliongli tliev may themselves be imifovm in cliaracter,
they yield during many generations astonishingly diversified
offspring. The breeder is driven to despair, and concludes
that he will never form an intermediate race. But from the
cases already given, and from others which have been re-
corded, it appears that patience alone is necessary ; as Mr.
Spooner remarks, "nature opposes no barrier to successful
admixture ; in the course of time, by the aid of selection and
careful weeding, it is practicable to establish a new breed."
After six or seven generations the hoped-for result will in
most cases be obtained ; but even then an occasional reversion,
or failure to keep true, may be expected. The attempt,
however, will assuredly fail if the conditions of life bo
decidedly unfavourable to the characters of either parent-
breed. ^°

Although the grandchildren and succeeding generations
of cross-bred animals are generally variable in an extreme
degree, some curious exceptions to the rule have been observed
both with crossed races and species. Thus Boitard and
Corbie ^^ assert that from a Pouter and a Eunt " a Cavalier
will appear, which we have classed amongst pigeons of pure
race, because it transmits all its qualities to its posterity."
The editor of the ' Poultry Chronicle ' ^^ bred some bluish
fowls from, a black Spanish cock and a Malay hen ; and these
remained true to colour "generation after generation." The
Himalayan breed of rabbits was certainly formed by crossing
two sub-varieties of the silver-grey rabbit ; although it sud-
denly assumed its present character, which differs much from
that of either parent-breed, yet it has ever since been easily
and truly propagated. I crossed some Labrador and Penguin
ducks, and recrossed the mongrels with Penguins ; afterwards
most of the ducks reared during three generations were nearly
uniform in character, being brown with a white crescentic
mark on the lower part of the breast, and with some Avhite
spots at the base of the beak ; so that by the aid of a little
selection a new breed might easily have been formed. With

so See Colin's ' Traite de Phys. well treated.
Comp. de!i Animaux Domesciquos,' ^'' ' Les Pigeons,' p. 37.

(x>m."ii. p. 536, where this subject is ^^ Vol. i., 1854, p. 101.

76 ON CROSSING AS A" CAUSE Chap. XV.

regard to crossed varieties of plants, Mr. Beaton remarks ^^
that " Melville's extraordinary cross between the Scotch kale
and an early cabbage is as true and genuine as any on record ;"
but in this case no doubt selection was practised. Gartner ^*
has given five cases of hybrids, in which the progeny kept
constant ; and hybrids between Dlanthus armeria and deltoides
remained true and uniform to the tenth generation. Dr.
Herbert likewise showed me a hybrid from two species of
Loasa which from its first production had kept constant
during several generations.

We have seen in the first chapter, that the several kinds
of dogs are almost certainl}'" descended from more than one
species, and so it is with cattle, pigs and some other domesti-
cated animals. Hence the crossing of aboriginally distinct
species probably came into play at an early period in the
formation of our present races. From Eiitimeyer's observa-
tions there can be little doubt that this occurred with cattle ;
but in most cases one foim will probably liave absorbed and
obliterated the other, for it is not likely that semi-civilized
men would have taken the necessary pains to modify by
selection their commingled, crossed, and fluctuating stock.
Nevertheless, those animals which were best adapted to their
conditions of life would have survived through natural
selection ; and by this means crossing will often have in-
directly aided in the formation of primeval domesticated
breeds. Within recent times, as far as animals are concerned,
the crossing of distinct species has done little or nothing to-
wards the formation or modification of our races. It is not yet
known whether the several species of silk-moth which have
been recently crossed in France will yield permanent races.
With plants which can be multiplied by buds and cuttings,
hybridisation has done wonders, as with many kinds of Eoses,
Rhododendrons, Pelargoniums, Calceolarias, and Petunias.
Nearly all these plants can be propagated by seed, most of
them freely ; but extremely few or none come true by seed.

Some authors believe that crossing is the chief cause of
variability, — that is, of the appearance of absolutely new

'^ ' Cottage Gardener,' 1856, p. ^* ' Bastarderzegung,' s. 55-3.

110.

Chap. XV. OF THE MODIFICATION OF RACES. 77

characters. Some have gone so far as to look at it as the
sole cause ; but this conclusion is disproved by the facts
given in the chapter on Bud-variation. The belief that
characters not present in either parent or in their ancestors
frequently originate from crossing is doubtful ; that they
occasionally do so is probable ; but this subject will be more
conveniently discussed in a future chapter on the causes of
Variability.

A condensed summary of this and of the three following
chapters, together with some remarks on Hybridism, will be
given in the nineteenth chapter.

78 CAUSES WHICH CHECK Chap. XVL

CHAPTER XVI.

CAUSES WHICH INTERFERE WITH THE FREE CROSSING OF
VARIETIES — INFLUENCE OF DOMESTICATION ON FERTILITY.

DIFFICULTIES IN JUDGING OF THE FERTILITY OF VARIETIES WHEN CROSSED

VARIOUS CAUSES WHICH KEEP VARIETIES DISTINCT, AS THE PERIOD

OF BREEDING AND SEXUAL PREFERENCE — VARIETIES OF WHEAT SAID TO
BE STERILE WHEN CROSSED — VARIETIES OF MAIZE, VERBASCUM, HOLLY-
HOCK, GOURDS, MELONS, AND TOBACCO, RENDERED IN SOME DEGREE
MUTUALLY STERILE — DOMESTICATION ELIMINATES THE TENDENCY TO
STERILITY NATURAL TO SPECIES WHEN CROSSED — ON THE INCREASED
FERTILITY OF UNCROSSED ANIMALS AND PLANTS FROM DOMESTICATION
AND CULTIVATION.

The domesticated races of both animals and plants, vvlien
crossed, are, with extremely few exceptions, quite prolific, — in
some cases even more so than the purely-bred parent-races.
The offspring, also, raised from such crosses are likewise, as
we shall see in the following cha23ter, generally more vigorous
and fertile than their parents. On the other hand, species
when crossed, and their hybrid offspring, are almost invariably
in some degree sterile ; and here there seems to exist a broad
and insuperable distinction between races and species. The
importance of this subject as bearing on the origin of species
is obvious ; and we shall hereafter recur to it.

It is unfortunate how few precise observations have been
made on the fertility of mongrel animals and plants during
several successive generations. Dr. Broca ^ has remarked
that no one has observed whether, for instance, mongrel dogs,
bred iiiter se, are indefinitely fertile ; yet, if a shade of in-
fertility be detected by careful observation in the offspring of
natural forms when crossed, it is thought that their specific
distinction is proved. But so many breeds of sheep, cattle,
pigs, dogs, and poultry, have been crossed and recrossed in
various w^ays, that any sterility, if it had existed, would from
"being injurious almost certainly have been observed. In

* * Journal de Physiolog.,' torn, ii., 1859, p. 385.

Chap. XVI. THE CROSSING OF VAEIETIKS. 79

investigating the fertility of crossed varieties many source of
doTibt occur. Whenever the least trace of sterility between
two plants, however closely allied, was observed by Kolreuter,
and more especially by Gartner, who counted the exact num-
ber of seed in each capsule, the two forms wore at once ranked
as distinct species ; and if this rule be followed, assuredly it
will never be proved that varieties when crossed are in any
degree sterile. We have formerly seen that certain breeds of
dogs do not readily pair together ; but no observations have
been made whether, when paired, they produce the full
number of young, and whether the latter are perfectly fertile
inter se ; but, supposing that some degree of sterility weie
found to exist, naturalists would simply infer that these
breeds were descended from aboriginally distinct species; and
it would be scarcely possible to ascertain whether or not this
explanation was the true one.

The Sebright Bantam is much less prolific than any other
breed of fowls, and is descended from a cross between two
very ditstinct breeds, recrossed by a third sub-variety. But it
would be extremely rash to infer that the loss of fertility was
in any manner connected with its crossed origin, for it mav
with more probability be attributed either to long-continued
close interbreeding, or to an innate tendency to sterility
correlated with the absence of hackles and siclde tail-feathers.

Before giving the few recorded cases of forms, which must
be ranked as varieties, being in some degree sterile when
crossed, I may remark that other causes sometimes inteifere
with varieties freely intercrossing. Thus they may differ too
greatly in size, as with some kinds of dogs and fowls : for
instance, . the editor of the ' Journal of Horticulture, &c.,' ^
says that he can keep Bantams with the larger breeds without
much danger of their crossing, but not with the smaller
breeds, such as Games, Haraburgs, &g. With plants a
difference in the period of flowering serves to keep varieties
distinct, as with the various kinds of maize and wheat : thus
Colonel Le Couteur ^ remarks, " the Talavera wheat, fiom
flowering much earlier than any other kind, is sure to

» Dec. 18G3, p. 484. ' Oa -The Varieties of Wheat,' p. 66.

80 CAUSES WHICH CHECK Guar XVI.

continue pure." In different parts of the Falkland Islands
the cattle are breaking up into herds of different coloui s ;
and those on the higher ground, which are generall}'" white,
usually breed, as I am informed by Sir J. Sulivan, three
months earlier than those on the lowland ; and this would
manifestly tend to keep the herds from blending.

Cei tain domestic races seem to prefer breeding with their
own kind ; and this is a fact of some importance, for it is a step
towards that instinctive feeling which helps to keep closely
allied species in a state of nature distinct. We have now
abundant evidence that, if it were not for this feeling, many
more hybrids would be naturally produced than in this 'case
We have seen in the first chapter that the alco dog of Mexico
dislikes dogs of other breeds ; and the hairless dog of
Paraguay mixes less readily with the European i-aces, than
the latter do with each other. In Germany the female Spitz-
dog is said to receive the fox more readily than will other
dogs ; a" female Australian Dingo in England attracted the
wild male foxes. But these differences in the sexual instinct
and attractive power of the various breeds may be wholly
due to their descent from distinct species. In Paraguay the
horses have much freedom, and an excellent observer * believes
that the native horses of the same colour and size prefer
associating with each other, and that the horses which have
been imported from Entre Eios and Banda Oriental into
Paraguay likewise prefer associating together. In Circassia
six sub-races of the horse have received distinct names ; and
a native proprietor of rank^ asserts that horses of three of
these races, whilst living a free life, almost always refuse to
mingle and cross, and will even attack one another.

It has been observed, in a district stocked with heavy
Lincolnshire and light Norfolk sheep, that both kinds, though
bred together, when turned out, " in a short time separate to
a sheep ; " the Lincolnshires drawing off to the rich soil, and
the Norfolks to their own dry light soil ; and as long as there
is plenty of grass, " the two breeds keep themselves as

* Rengger, ' Saugethiere von Para- and De Quatrefages, in ' Bull. Soc.
guay,' s. 336. d'Acclimat.,' torn, viii,, July, 1861,

* See a memoir by MM. Lherbette p. 312.

Chap. XVI. THE CROSSING OF VARIETIES. 81

distinct as rooks and pigeons." In this case different habits
of life tend to keep the races distinct. On one of the Faroe
islands, not more than half a mile in diameter, the half- wild
native black sheep are said not have readily mixed with the
imported white sheep. It is a more curious fact that the
semi-monstrous ancon sheep of modern origin "have been
observed to keep together, separating themselves from the
rest of the flock, when put into enclosures with othei sheep. "^
With respect to fallow-deer, which live in a semi domesti-
cated condition, Mr. Bennett ^ states that the dark and pale
coloured herds, which have long been kept together in the
Forest of Dean, in High Meadow Woods, and in the New
Forest, have never been known to mingle : the dark-coloured
deer, it may be added, are believed to have been first brought
by James I. from Norway, on account of their greater
hardiness. I imported from the island of Porto Santo two of
the feral rabbits, which differ, as described in the fourth
chapter, from common rabbits ; both proved to be males,
and, though they lived during some years in the Zoological
Gardens, the superintendent, Mr. Bartlett, in vain endea-
voured to make them breed with various tame kinds ; but
whether this refusal to breed was due to any change in the
instinct, or simply to their extreme wildiiess, or whether
confinement had rendered them sterile, as often occurs, cannot
be determined.

Whilst matching for the sake of experiment many of the
most distinct breeds of pigeons, it frequently appeared to
me that the birds, though faithful to their marriage vow,
retained some desire after their own kind. Accordingly I
asked Mr. Wicking, who has kept a larger stock of various
breeds together than any man in England, whether he thought
that they would prefer pairing with their own kind, suppos-
ing that there were males and females enough of each ; and
he without hesitation answered that he was convinced that

« For the Norfolk sheep, see Mar- ^ White's ' Nat. Hist, of Selbourne,'

shall's 'Rural EconDmy of Norfolk,' edited by Bennett, p. 39. With respect

vol. ii. p. 136. See Rev. L. Landt's to the origin of the dark-coloured

' Description of Faroe,' p. QQ. For deer, see * Souie Account of English

the ancon sheep, see ' Phil. Transact.,' Deer Parks,' by E. P. Shirley, Esq.
1813, p. 90.

82 CAUSES WHICH CHECK Chap. XYI.

tliis was the case. It lias often been noticed that the
dovecot pigeon seems to have an actual aversion towards the
several fancy breeds ; ^ yet all have certainly sprung from a
common progenitor. The Rev. W. D. Fox informs me that
his flocks of white and common Chinese geese kept distinct.

These facts and statements, though some of them are
incapable of proof, resting only on the opinion of experienced
observers, show that some domestic races are led by different
habits of life to keep to a certain extent separate, and that
others prefer couj)ling with their own kind, in the same
manner as species in a state of nature, though in a much less
degree.

With respect to sterility from the crossing of domestic races, 1
know of no well-ascertained case with animals. This fnct, seeing
the great difference in structure between some breeds of i^igeons,
fowls, pigs, dogs, &c., is extraordinary, in contrast with the sterility
of many closely allied natural species when crossed ; but we shall
hereafter attempt to show that it is not so extraordinary as it at
first appears. And it may be well here to recall to mind that the
amount of external difference between two species is not a safe guide
for predicting whether or not they will breed together, — some
closely allied species when crossed being utterly sterile, and otliers
which are extremely unlike being moderately fertile. I have said
that no case of sterility in crossed races rests on satisfactory evi-
dence ; but here is one which at first seems trustworthy, Mr.
Youatt,^ and a better authority cannot be quoted, states, that
formerly in Lancashire crosses were frequently made between
longhorn and shorthorn cattle ; the first cross was excellent, but
the produce was uncertain ; in the third or fourth generation the
cows were bad milkers ; " in addition to which, there was much
uncertainty whether the cows would conceive ; and full one-third
of the cows among some of these half-breds failed to be in calf."
This at first seems a good case : but Mr. Wilkinson states,^*' that a
breed derived from this same cross was actually established in
another part of England; and if it had failed in fertility, the fact
would surely have been noticed. Moreover, supposing that Mr.
Youatt had proved his case, it might be argued that the sterility
was wholly due to the two parent-breeds being descended from
primordially distinct species.

In the case of plants Gartner states that he fertilised thirteen
heads (and subsequently nine others) on a dwarf maize bearing

* * The Dovecote,* by the Rev. E. S. » * Cattle,' p. 202.

Dixon, p. 155 ; Bechstein, ' Natur- ^° Mr. J, Wilkinson, in ' Remarks

gesch. Deutschlands,' Band iv., 1795, addressed to Sir J Sebright," 1820,

s. 17. p. 38.

Ohap. xvl the crossing of varieties. 83

yellow seed" with pollen of a tall maize having red seed; and one
head alone produced good seed, but only five in number. Though
these plants are monoecious, and therefore do not require castration,
yet I should have suspected some accident in the manipulation, had
not Gartner expressly stated that he had during many years grown
these two varieties together, and they did not spontaneously cross ;
and this, considering that the plants are monoecious and abound
with pollen, and are well known generally to cross freely, seems
explicable only on the belief that these two varieties are in some
degree mutually infertile. The hybrid plants raised from the above
five seeds were intermediate in structure, extremely variable, and
perfectly fertile.^^ In like manner Prof. Hildebrand^^ could not
succeed in fertilising the female flowers of a plant bearing brown
grains with pollen from a certain kind bearing yellow grains ;
although other flowers on the same plant, which were fertilised
Avith their own pollen, yielded good seed. No one, I believe, even
suspects that these varieties of maize are distinct species ; but had
the hybrids been in the least sterile, no doubt Gartner would at
once have so classed them. I may here remark, that with undoubted
species there is not necessarily any close relation between the
sterility of a first cross and that of the hybrid offspring. Some
species can be crossed with facility, but produce utterly sterile
hybrids; others can be crossed with extreme difficulty, but the
hybrids when produced are moderately fertile. I am not aware,
however, of any instance quite like this of the maize, namely, of a
first cross made with difficulty, but yielding perfectly fertile hybrids.^*
The following case is much more remarkable, and evidently per-
plexed Gartner, whose strong wish it was to draw a broad line of
distinction between species and varieties. In the genus Verbascum,
he made, during eighteen years, a vast number of experiments, and
crossed no less than 1085 flowers and counted their seeds. Many
of these experiments consisted in crossing white and yellow varieties
of both V. lychnitis and V. Uattaria with nine other species and
their hybrids. That the white and yellow flowered plants of these
two species are really varieties, no one has doubted ; and Gartner
actually raised in the case of both species one variety from the seed of
the other. Now in two of his works ^^ he distinctly asserts that crosses
between similarly-coloured flowers yield more seed than between
dissimilarly-coloured ; so that the yellow-flowered variety of either
species (and conversely with the white-flowered variety), when
crossed with pollen of its own kind, yields more seed ttian when

^^ ' Bastarderzeugung,* s. 87, 169. varieties of wheat became sterile in

See also the Table at the end of the fourth generation ; but he now

volume. admits (' Improvement of the Cereals,*

*2 ' Bastarderzeugung,' s. 87, 577. 1873) that thi« was an error.

" *Bot. Zeitung,' 1868, p. 327. ^^ ' Kenntniss der Befruchtung,' s.

^* Mr. Shirreff formerly thought 137 ; ' Bastarderzeugung,' s. 92, 181.

(' Gard. Chron.,' 1858, p. 77 1) that the On raising the two varieties from seed,

offspring from a cross between certain see s. 307.

84 CAUSES WHICH CHECK Chap. XVL

crossed with that of the white variety ; and so it is when dififerently
coloured species are crossed. The general results may be seen in the
Table at the end of his volume. In one instance he gives ^^ the
following details; but I must premise that Gartner, to avoid ex-
aggerating the degree of sterility in his crosses, always compares the
maximum number obtained from a cross with the average number
naturally given by the pure mother-plant. The white variety of
V. lychnitis, naturally fertilised by its own pollen, gave from an
average of twelve caj^sules ninety-six good seeds in each; whilst
twenty flowers fertilised with pollen from the yellow variety of this
same species, gave as the maximum only eighty-nine good seeds ; so
that we have the proportion of 1000 to 908, according to Gartner's
usual scale. I should have thought it possible that so small a difference
in fertility might have been accounted for by the evil effects of the
necessary castration ; but Gartner shows that the white variety of V.
lychnitis, when fertilised iirst by the white variety of V. blnttaria, and
then by the yellow variety of this species, yielded seed in the propor-
tion of 62'i to 438 ; and in both these cases castration was performed.
Now the sterility which results from the crossing of the differently
coloured varieties of the same species, is fully as great as that which
occurs in many cases when distinct species are crossed. Unfortu-
nately Gartner compared the results of the first unions alone, and
not the sterility of the two sets of hybrids produced from the white
variety of V. lychnitis when fertilised by the white and yellow
varieties of V. blatt'tria, for it is probable that they would have
differed in this respect.

Mr. J. Scott has given me the results of a series of experiments on
Verbascum, made by him in the Botanic Gardens of Edinburgh, i'^ He
repeated some of Gartner's experiments on distinct species, but
obtained only fluctuating results, some confirmatory, the greater
number contradictory ; nevertheless these seem hardly sufficient to
overthrow the conclusion arrived at by Gartner from experiments
tried on a larger scale. Mr. Scott also experimented on the relative
fertility of unions between similarly and dissimilarly- coloured
varieties of the same species. Thus he fertilised six flowers of the
yellow variety of V. lychnitis by its own pollen, and obtained six
capsules; and calling, for the sake of comparison, the average
number of good seed in each of their capsules one hundred, he found
that this same yellow variety, when fertilised by the white variety,
yielded from seven capsules an average of ninety-four seed. On the
same principle, the white variety of V. lychnitis by its own pollen
Cfrom six capsules), and by the pollen of the yellow variety (eight
capsules), yielded seed in the proportion of 100 to 82. The yellow
variety of V. thapsus by its own pollen (eight capsules), and by
that of the white variety (only two capsules), yielded seed in the
proportion of 100 to 94. Lastly, the white variety of V. hlattaria

^* * Bastarderzeugung,' s. 216. published ia 'Journ. Asiatic Soc. o/

*" The results have since been Bengal,' 1867, p. 145.

Chap. XVI.

THE CROSSING OF VAEIETIES.

85

by its own pollen (eight capsules), and by that of the yellow variety
(five capsules), yielded seed in the proportion of 100 to 79. So that
in every case the unions of similarly-coloured varieties of the same
)^pecies were more fertile than the unions of dissimilarly-coloured
varieties ; when all the cases are grouped together, the difference of
fertilitv is as ICO to 86. Some additional trials were made, and
altogether thirty-six similarly-coloured unions yielded thirty-five
good capsules ; whilst thirty-five dissimilarly-coloured unions yielded
OFily twenty-six good capsules. Besides the foregoing experiments,
the purple V. phoeniceum was crossed by a rose-coloured and a white
variety of the same species ; these two varieties were also crossed
together, and these several unions yielded less seed than V. phoe-
niceum by its own pollen. Hence it follows from ]\Ir. Scott's experi-
ments, that in the genus Yerbascum the similarly and dissimilarly-
coloured varieties of the same species behave, when crossed, like
closely allied but distinct species.^^

This remarkable fact of the sexual aflSnity of similarly-coloured
varieties, as observed by Gartner and Mr. Scott, may not be of very
rare occurrence; for the subject has not been attended to by others.
The following case is worth giving, partly to show how difficult it
is to avoid error. Dr. Herbert ^^ has remarked that variously-
coloured double varieties of the Hollyhock (Althea rosea) may be
raised with certainty by seed from plants growing close together.
I have been informed that nurserymen who raise seed for sale do
not separate their plants ; accordingly I procured seed of eighteen
named varieties; of these, eleven varieties produced sixty-two
plants all perfectly true to their kind ; and seven produced forty-
nine plants, half of which were true and half false. Mr. Masters of

** The following facts, given by
Kclreuterin his ' Dritte Fortsetzung,'
ss. 34, 39, appear at first sight strongly
to confirm Mr. Scott's and Gartner's
statements ; and to a certain limited
extent they do so. Koh-euter asserts,
from innumerable observations, that
insects incessantly carry pollen from
one species and variety of Yerbascum
to another ; and I can confirm this
assertion ; yet he found that the
white and yellow varieties of Verbas-
cum lychnitis often grew wild mingled
together : moreover, he cultivated
these two varieties in considerable
numbers during four years in his
garden, and they kept true by seed ;
but when he crossed them, they pro-
duced flowers of an intermediate tint.
Hence it might have been thought
that both varieties must have a
stronger elective affinity for the pollen

26

of their own variety than for that of
the other ; this elective affinity, I
may add of each species for its own
pollen (Kolreuter, 'Dritte Forts.' s.
39, and Gartner, ' Bastarderz., ^jass/m)
being a perfectly well-ascertained
power. But the force of the fore-
going facts is much lessened by
Gartner's numerous experiments, for,
dirtierently from Kolreuter, he never
once got (' Bastarderz.,' s. 307) an
mtermediate tint when he crossed the
yellow and white flowered varieties
of Verbascum. So that the fact of
the white and yellow varieties keep-
ing true to their colour by seed does
not proA'-e that they were not mutual-
ly fertilised by the pollen carried by
insects from one to the other.

18 ' Amaryllidaceee,' 1837, p. 366.
Gartner has made a similar observa-
tion.

86 CAUSES WHICH CHECK Chap. XYl.

Canterbury has given me a more striking case ; he saved seed from
a great bed of twenty-four named varieties planted in closely ad-
joining rows, and each variety reproduced itself truly with only
sometimes a shade of difference in tint. Now in the hollyhock the
pollen, which is abundant, is matured and nearly all shed before
the stigma of the same flower is ready to receive it ; ^° and as bees
covered with pollen incessantly fly from plant to plant, it would
appear that adjoining varieties could not escape being crossed. As,
however, this does not occur, it appeared to me probable that the
pollen of each variety was prepotent on its own stigma over that of
all other varieties, but I have no evidence on this point. Mr. C.
Turner of Slough, well known for his success in the cultivation of
this plant, informs me that it is the doubleness of the flowers which
prevents the bees gaining access to the pollen and stigma ; and he
finds that it is difficult even to cross them artificially. Whether
this explanation will fully account for varieties in close proximity
propagating themselves so truly by seed, I do not know.

The following cases are worth giving, as they relate to monoecious
forms, which do not require, and consequently cannot have been
injured by, castration. Girou do Buzareingues crossed what he
designates three varieties of gourd,^^ and asserts that their mutual
fertilisation is less easy in proportion to the difference which they
present. I am aware how imperfectly the forms in this group were
until recently know^n ; but Sageret,'^ who ranked them according to
their mutual fertilitv, considers the three forms above alluded to as
varieties, as does a far higher authority, namely, M. Naudin.^^
Sageret^^has observed that certain melons have a greater tendency,
whatever the cause may be, to keep true than others ; and M. Naudin,
who has had such immense experience in this group, informs me
that he believes that certain varieties intercross more readily than
others of the same species ; but he has not proved the truth of this
conclusion ; the frequent abortion of the pollen near Paris being
one great difficulty. Nevertheless, he has grown close together,
during seven years, certain forms of Citrullus, which, as they
could be artificially crossed with perfect facility and produced
fertile offspring, are ranked as varieties ; but these forms when not
artificially crossed kept true. Many other varieties, on the other
hand, in the same group cross with such facility, as M. Naudin
repeatedly insists, that without being grown far apart they cannot
be kept in the least true.

Another case, though somewhat different, may be here given, as

-" Kolreuter first observed this fact, ^- ' Memoire sur les Cucurbitacese,'

* Mem. de I'Acad. de St. Petersburg,' 1826, pp. 46, 55.

vol. iii. p. 127. See also C. K. 23 < Annates des Sc. Nat.,' 4th

Sprengel, * Das Entdeckte Geheimniss,' series, torn. vi. M. Naudin considers

s. 345. these forms as undoubtedly varieties

'* Namely, Barbarines, Pastissons, of Cucurbiti pepo.

Giraumous : ' Annal. des Sc. Nat.' ^* ' Mem. Cucurb.,' p. 8.
torn XXX., 1833, pp. 398 and 405.

Chap. XVI.

THE CROSSING OF VARIETIES.

87

it is highly remarkable, and is established on excellent evidence.
Kolreuter minutely describes five varieties of the common tobacco,^^
which were reciprocally crossed, and the offspring were intermediate
in character and as fertile as their parents : from this fact Kolreuter
inferred that they are really varieties ; and no one, as far as I can
discover, seems to have doubted that such is the case. He also
crossed reciprocally these five varieties with N. glutmosa, and they
yielded very sterile hybrids; but those raised from the var.percnnis,
whether used as the father or mother plant, were not so sterile as
the hybrids from the four other varieties.^^ So that the sexual
capacity of this one variety has certainly been in some degree
modified, so as to approach in nature that of N. glutinosaj-^''

These facts with respect to plants show that in some few
cases certain varieties have had their sexual powers so far
modified, that they cross together less readily and yield less
seed than other varieties of the f^ame species. We shall
presently see that the sexual functions of most animals and
plants are eminently liable to be affected by the conditions
of life to which they are exposed ; and hereafter we shall

" 'Zweite Forts.,' s. 53, namely,
Nicotiana major vulgaris ; (2) peren-
nis ; (3) transylvanica ; (4) a sub-
var. of the last ; (5) major latifol. jl.
alb.

2^ Kolreuter was so much struck
with this fact that he suspected th.it
a little pollen of iV. glutinosa in one
of his experiments might have acci-
dentally got mingled with that of
var. perennis, and thus aided its fer-
tilising power. But we now know
conclusively from Gartner (' Bastar-
derz.,' s. 34, 43) that the pollen of
two species never acts coiijointly on a
third species ; still less will the pollen
of a distinct species, mingled with a
plant's own pollen, if the latter be
present in sutficient quantity, have
any effect. The sole efiect of mingling
two kinds of poUe^i is to produce in
the same capsule seeds which j'ield
plants, some taking after the one and
some after the other parent.

*^ Mr. Scott has made some olser-
vations on the absolute sterility of a
purple and white primrose (^Primula
vulgaris) when fertilised by pollen
from the common primrose (' Journal

of Proc. of Linn. Soc.,' vol. viii., 1864,
p. 98) ; but these observations require
confirmation, I raised a number of
purple-flowered long-styled seedlings
from seed kindly sent me by Mr.
Scott, and, though they were all in
some degree sterile, they were much
more fertile with polhm taken from
the common primrose than with their
own pollen. Mr. Scott has likewise
described a red equal-styled cowslip
(P. veris, ibid. p. 106), which was
found by him to be highly sterile
when crossed with the common cow-
slip ; but this was not the case with
several equal - styled red seedlings
raised by me from his plant. This
variety of the cowslip presents the
remarkable peculiarity of combining
male organs in every respect like
those of the short-styled form, with
female organs resembling in function
and partly in structure those of the
long-styled form ; so that we have
the singular anomaly of the two
forms combined in the same flower.
Hence it is not surprising that these
flowers should be spontaneously self-
fertile in a high degree.

88 DOMESTICATION ELIMINATES STERILITY. Chap. XVI.

briefly discuss the conjoint bearing of this fact, and others,
on the difference in fertility between crossed varieties and
crossed species.

Domestication eliminates the tendency to Sterility which is general

with Species lohen crossed.

This hypothesis was first propounded by Pallas,^^ and has
been adopted by several authors. I can find hardly any
direct facts in its sujoport ; but unfortunately no one has
compared, in the case of either animals or plants, the fertility
of anciently domesticated varieties, w^hen crossed with a
distinct species, with that of the wild parent species when
similarly crossed. No one has compared, for instance, the
fertilit}'' of Gallus hanJciva and of the domesticated fowl, when
crossed with a distinct species of Gallus or Phasianus ; and
the experiment w^ould in all cases be surrounded by many
difficulties. Dureau de la Malle, who has so closely studied
classical literature, states -^ that in the time of the Eomans
the common mule was produced with more difficulty than at
the present day ; but whether this statement may be trusted
I know not. A much more important, though somewhat dif-
ferent, case is given by M. Groenland,^° namely, that plants,
known from their intermediate character and sterilit}^ to
be hybrids between ^gilops and wheat, have perpetuated
themselves under culture since 1857, with a rapid but varying
increase of fertility in each generation. In the fourth generation
the plants, still retaining their intermediate character, had
become as fertile as common cultivated wheat.

The indirect evidence in favour of the Pallasian doctrine
appears to me to be extremely strong. In the earlier chapters
I have shown that our various breeds of the dog are descended
from several wild species ; and this probably is the case with
sheep. There can be no doubt that the Zebu or humped
Indian ox belongs to a distinct species from European cattle :
the latter, moreover, are descended from two forms, which
may be called either species or races. We have good evidence

" 'Act. Acad. St. Petersburg,' (1st series), p. 61.
1780, part ii. pp. 84, 100. ^^ ' Bull. Bot. Soc. de France,' Dec

*9 ' Annales des Sc. Nat.' torn. xxi. 27th, 1861, torn. viii. p. 612.

Chap. XVI. INCREASED FERTILITY FROM DOMESTICATION. 89

that our domesticated pigs belong to at least two specific
types, S. scrofa and indicus. Kow a widely extended analogy
leads to the belief that if these several allied species, when
first reclaimed, had been crossed, they would have exhibited,
both in their first unions and in their hybrid offspring, some
degree of sterility. Nevertheless, the several domesticated
races descended from them are now all, as far as can be
ascertained, perfectly fertile together. If this reasoning be
trustworthy, and it is apparently sound, we must admit the
Pal las i an doctrine that long-continued domestication tends
to eliminate that sterility which is natural to species when
crossed in their aboriginal state.

Ofi increased Fertility from Domestication and Cultivation.

Increased fertility from domestication, without any refer-
ence to crossing, may be here briefly considered. This subject
bears indirectly on two or three points connected with the
modification of organic beings. As Buffon long ago re-
marked,^^ domestic animals breed oftener in the year and
produce more young at a birth than wild animals of the same
species ; they, also, sometimes breed at an earlier age. The
case would hardly have deserved further notice, had not
some authors lately attempted to show that fertility increases
and decreases in an inverse ratio with the amount of food.
This strange doctrine has apparently arisen from individual
animals when supplied with an inordinate quantity of food,
and from plants of many kinds when grown on excessively
rich soil, as on a dunghill, becoming sterile : but to this
latter point I shall have occasion presently to return. With
hardly an exception, our domesticated animals, which have
been long habituated to a regular and copious supply of food,
witliout the labour of searching for it, are more fertile than
the corresponding wild animals. It is notorious how fre-
quently cats and dogs breed, and how many young they
produce at a birth. The wild rabbit is said generally to

^^ Quoted by Isid. Geoffroy St. the present subject has appeared in

Hilaire, ' Hist. Naturelle Generale,' Mr. Herbert Spencer's ' Principles of

torn. iii. p. 476. Since this MS. has Biology,' vol. ii., 1867, p. 457 ct seq.
been sent to press a full discussion on

90

INCREASED FERTILITY

Chap. XVI.

breed four times yearly, and to produce each time at most
six young ; tlie tame rabbit breeds six or seven times yearly,
produc^'ng each time from four to eleven young ; and
Mr. Harrison AVeir tells me of a case of eighteen young
having been produced at a birth, all of which survived.
The ferret, though generally so closely confined, is more
prolific than its supposed wild prototype. The wild sow is
remarkaldy prolific; she often breeds twice in the year, and
bears from four to eight and sometimes even twelve young ;
but the domestic sow regularly breeds twice a j^ear, and would
breed oftener if permitted ; and a sow that produces less than
eight at a birth " is worth little, and the sooner she is fattened
for the butcher the better." The amount of food affects the
fertility of the same individual : thus sheep, which on moun-
tains never produce more than one lamb at a birth, when
brought down to lowland pastures frequently bear twins.
This difference apparently is not due to the cold of the higher
land, for !>heep and other domestic animals are said to be ex-
tremely prolific in Lapland. Hard living, also, retards the
period at which animals conceive ; for it has been found dis-
advantageous in the northern islands of Scotland to allow
cows to bear calves before the}^ are four years old.^^

Birds offer still better evidence of increased fertility from domesti-
cation : the hen of the wild (Julius binkiva lays from six to ten
eggs, a number which would be thought nothing of with the
domestic hen. The wild duck lays from live to ten eggs ; the tame
one in the course of the year from eighty to one hundred. The wild
grey-lag goose lays from five to eight eggs ; the tame from thirteen
to eighteen, and she lays a second time ; as Mr. Dixon has remarked,
" high-feeding, care, and moderate warmth induce a habit of proli-
ficacy which becomes in some measure hereditary." Whether the
semi-domesticated dovecot pigeon is more fertile than the wild
rock-pigeon, C. livia, I know not ; but the more thoroughly domesti-

32 For cats and dogs, &c., see Bel-
lingeri, iu 'Annal. des Sc. Nat.,' 2nd
series, Zoolog., torn. xii. p. 155. For
ferrets, Bechstein, ' Naturgeschichte
Deutschlands,' Band i., 18i)l, s. 786,
795. For rabbits, ditto, s. 1123, 1131 ;
and Bronn's ' Geschichte der Natur.,'
B. ii. s, 99. For mountain sheep,
ditto, s. 102. For the fertility of the

wild sow, see Bechstein's ' Naturgesch.
Deutschlands,' B. i., 1801, s. 534; for
the domestic pig, Sidney's edit, of
Youatt on the Pig, 1860, p. 62. With
respect to Lapland, see Acerbi's
'Travels to the North Cape,' Eng.
translat., vol. ii. p. 222. About the
Highland cows, see Hogg on Sheop,
p. 263.

Chap. XVI. FROM DOMESTICATION. 91

cated breeds are nearly twice as fertile as dovecots: the latter,
however, when caged and highly fed, become equally fertile with
house pigeons. 1 hear from Judge Caton that the wild turkey in
the United States does not breed when a year old, as the domesti-
cated turkeys there invarial)ly do. The peahen alone of domesti-
cated birds is rather more fertile, according to some accounts, when
wild in its native Indian home, than in Europe when exposed to our
much colder climate.^

With respect to plants, no one would expect wheat to tiller more,
and each ear to produce more grain, in poor than in rich soil ; or to
get in poor soil a heavy crop of peas or beans. Seeds vary so much
in number that it is difficult to estimate them ; but on comparing
beds of carrots in a nursery garden with wild plants, the former
seemed to produce about twice as much seed. Cultivated cabbages
yielded thrice as many pods by measure as wild cabbages from the
rocks of South Wales, The excess of berries produced by the culti-
vated asparagus in comjmrison with the wild jDlant is enormous.
No doubt many highly cultivated plants, such as pears, pineapples,
bananas, sugar-cane, &c., are nearly or quite sterile; and I am
inclined to attribute this sterility to excess of food and to other
unnatural conditions ; but to this subject I shall recur.

In some cases, as with the pig, rabbit, &c., and with, those
plants which are valued for tlieir seed, the direct selection of
the more fertile individuals has probably much, increased
their fertility; and in all cases this may have occurred in-
directly, from the better chance of some of the numerous
offspring from the more fertile individuals having been pre-
served. But with cats, ferrets, and dogs, and with plants
like carrots, cabbages, and asparagus, which are not valued
for their prolificacy, selection can have played only a sub-
ordinate part ; and their increased fertility must be attributed
to the more favourable conditions of life under which they
have long existed.

33 For the eggs of Gallns hankiv'i, Pigeons,' p. 158. With respect to

see Blyth, in 'Annals and Mag. of peacocks, according to Temminck

Nat. Hist.,' 2nd series, vol. i., iSiS, (' Hist. Nat. Gen. des Pigeons,' &c.,

p. 456. For wild and tame ducks, 1813, torn. ii. p. 41), the hen lays in

Macgillivray, ' British Birds,' vol. v. India even as many as twenty eggs ;

p. 37 ; and ' Die Enten,' s. 87. For but according to Jerdon and another

wild geese, L. Llovd, ' Scandinavian writer (quoted in Tegetmeier's

Adventures,' vol. "ii. 1854, P. 413; Poultry Book,' 1866, pp. 280, 28.'),

and for tame geese, ' Ornamental she there lays only from four to nine

Poultry,' by Rev, E. S. Dixon, p. 139. or ten eggs: in England she is said,

On the breeding of Pigeons, Pistor, in the ' Poultry Book,' to lay five or

* Das Ganze der Taubenzucht,' 1831, six, but another writer savs from

». 46 ; and Boitard and Corbie * Les eight to twelve eggs.

92 GOOD FROM CE0S8ING. Chap. XYU

CHAPTER XVII.

ON THE GOOD EFFECTS OF CROSSING, AND ON THE EVIL EFFECTS

OF CLOSK INTERBREEDING.

DEFINITION OF CLOSE INTERBREEDING — AUGMENTATION OP MORBID TEN-
DENCIES — GENERAL EVIDENCE OF THE GOOD EFFECTS DERIVED FROM
CROSSING, AND ON THE EVIL EFFECTS FROM CLOSE INTERBREEDING — ■
CATTLE, CLOSELY INTERBRED; HALF-WILD CATTLE LONG KEPT IN THE
SAME PARKS — SHEEP — FALLOW-DEER — DOGS, RABBITS, PIGS — MAN, ORIGIN
OF HIS ABHORRENCE OF INCESTUOUS MARRIAGES — FOWLS — PIGEONS — HIVE-
BEES — PLANTS, (JENERAL CONSIDERATIONS ON THE BENEFITS DERIVED FROM
CROSSING — MELONS, FRUIT-TREES, PEAS, CABBAGES, WHEAT, AND FOREST-
TREES — ON THE INCREASED SIZE OF HYBRID PLANTS, NOT EXCLUSIVELY
DUE TO THEIR STERILITY — ON CERTAIN PLANTS WHICH EITHER NOR-
MALLY OR ABNORMALLY ARE SELF-IMFOTENT, BUT ARE FERTILE, BOTH
ON THE MALE AND FEMALE SIDE, WHEN CROSSED WITH DISTINCT INDI-
VIDUALS EITHER OF THE SAME OR ANOTHER SPECIES — CONCLUSION.

The gain in constitutional vigour, derived from an occasional
cross between individuals of the same variety, but belonging
to distinct families, or between distinct varieties, bas not
been so largely or so frequently discussed, as have the evil
effects of too close interbreeding. But the former point is
the more important of the two, inasmuch as the evidence is
more decisive. The evil results from close interbreeding are
difficult to detect, for they accumulate slowly, and differ
much in degree with different species ; whiL-it the good effects
which almost invariablv follow a cross are from the first
manifest. It should, however, be clearly understood that the
advantage of close interbreeding, as far as the retention of
character is concerned, is indisputable, and often outweighs
the evil of a slight loss of constitutional vigour. In relation
to the subject of domestication, the whole question is of some
importance, as too close interbreeding interferes with the
improvement of old races. It is important as indirectly
bearing on Hybridism ; and possibly on the extinction of
species, when any form has become so rare that only a few
individuals remain within a confined area. It bears in an

Chap. XVII. EVIL FEOM INTERBREEDING. 93

important manner on the influence of free intercrossing, in
obliterating individual differences, and thus giving uniformity
of character to the individuals of the same race or species ; for
if additional vigour and fertility he thus gained, the crossed
offspring will multiply and prevail, and the ultimate result
will be far greater than otherwise would have occurred. Lastly,
the question is of high interest, as bearing on mankind. I shall
therefore discuss this subject at full length. As the facts which
prove the evil effects of close interbreeding are more copious,
though less decisive, than those on the good effects of crossing,
I shall, under each group of beings, begin with the former.

There is no difficulty in defining what is meant by a cross ;
but this is by no means easy in regard to " breeding in and
in " or " too close interbreeding," because, as we shall see,
different species of animals are differently affected by the
same degree of interbreeding. The pairing of a father and
daughter, or mother and son, or brothers and sisters, if carried
on during several generations, is the closest possible form of
interbreeding. But some good judges, for instance Sir J.
Sebright, believe that the pairing of a brother and sister is
much closer than that of parents and children ; for when the
father is matched with his daughter he crosses, as is said,
with only half his own blood. The consequences of close
interbreeding carried on for too long a time, are, as is 2;enerallv
believed, loss of size, constitutional vigour, and fertility,
sometimes accompanied by a tendency to malformation.
Manifest evil does not usually follow from pairing the nearest
relations for two, three, or even four generations ; but several
causes interfere with our detecting the evil — such as the
deterioration being very gradual, and the difficulty of dis-
tinguishing between such direct evil and the inevitable
augmentation of any morbid tendencies which may be latent
or apparent in the related parents. On the other hand, the
benefit from a cross, even when there has not been any very
close interbreeding, is almost invariably at once conspicuous.
There is good reason to believe, and this was the ojDinion of
that most experienced observer Sir J. Sebright,^ that the evil

» 'The Art of Improving the Breed, &c.,' 1809, p. 16.

94 GOOD FROM CROSSING. Chap. XVII.

effects of close interbreeding may be checked or quite pre-
vented by the related individuals being separated for a few
generations and exposed to different conditions of life. This
conclusion is now held by many breeders ; for instance Mr.
Carr ^ remarks, it is a well-known " fact that a change of soil
and climate effects perhaps almost as great a change in the
constitution as would result from an infusion of fresh blood."
I hope to show in a future work that consanguinity by itself
counts for nothing, but acts solely from related organisms gene-
rally having a similar constitution, and having been exposed
in most cases to similar conditions.

That any evil directl}'- follows from the closest interbreeding
has been denied by many persons ; but rarely by any practical
breeder ; and never, as far as I know, by one who has largely
bred animals which propagate their kind quickly. Many
physiologists attribute the evil exclusively to the combination
and consequent increase of morbid tendencies common to both
parents ; and that this is an active source of mischief there
can be no doubt. It is unfortunately too notorious that men
and various domestic animals endowed with a wretched
constitution, and with a strong hereditary disposition to
disease, if not actually ill, are fully capable of procreating
their kind. Close interbreeding, on the other hand, often
induces sterility ; and this indicates something quite distinct
from the augmentation of morbid tendencies common to both
parents. The evidence immediately to be given convinces me
that it is a great law of nature, that all organic beings profit
from an occasional cross with individuals not closely related
to them in blood ; and that, on the other hand, long-continued
close interbreeding is injurious.

Various general considerations have had much influence in
leading me to this conclusion ; but the reader will probably
rely more on special facts and opinions. The authority of
exj)erienced observers, even when they do not advance the
grounds of their belief, is of some little value. Kow almost
all men who have bred many kinds of animals and have
written on the subject, such as Sir J. Sebright, Andrew

* ' The History of the Rise and Progress of the Killerby, &c. Herds,' p. 41.

Chap. XVII. EVIL FROM INTERBREEDING. 95

Kniglit, &c.,^ have expressed the strongest conviction on the
impossibility of long-continued close interbreeding. Those
who have compiled works on agriculture, and have associated
much with breeders, such as the sagacious Youatt, Low, &c.,
liave strongly declared their opinion to the same effect.
Prosper Lucas, trusting largely to French authorities, has
come to a similar conclusion. The distinguished German
agriculturist Hermann von Nathusius, who has written the
most able treatise on this subject which I have met- with,
concurs ; and as I shall have to quote from this treatise, I
may state that Kathusius is not only intimately acquainted
with works on agriculture in all languages, and knows the
pedigrees of our British breeds better than most Englishmen,
but has imported many of our improved animals, and is him-
self an experienced breeder.

Evidence of the evil effects of close interbreeding can most
readily be acquired in the case of animals, such as fowls,
pigeons, &c., which propagate quickly, and, fix)m being kept
in the same place, are exposed to the same conditions. Now
I have inquired of very many breeders of these birds, and I
have hitherto not met with a single man who was not
thoroughly convinced that an occasional cross with another
strain of the same sub-variety was absolutely necessary.
Most breeders of highly improved or fanc}'' birds value their
own strain, and are most unwilling, at the risk, in their
opinion, of deterioration, to make a cross. The purchase of a
first-rate bird of another strain is expensive, and exchanges
are troublesome ; yet all breeders, as far as I can hear, ex-
cepting those who keep large stocks at different places for
the sake of crossing, are driven after a time to take this step.

Another general consideration which has had great influence
on my mind is, that with all hermaphrodite animals and
plants, which it might have been thought would have per-
petually fertilised themselves and been thus subjected for long
ages to the closest interbreeding, there is not a single species,
as far as I can discover, in which the structure ensures self-
fertilisation. On the contrary, there are in a multitude of

' For Andrew Knight, see A. 227. Sir J. Sebright's Treatise ha«
Talker, on 'Intermarriage,' 1838, p. ju>t been quoled.

96

GOOD FFvOM CROSSING.

Chap. XVII.

cases, as briefly stated in the fifteenth chapter, manifest
adaptations which favour or inevitably lead to an occasional
cross between one hermaphrodite and another of the same
species ; and these adaptive structures are utterl}^ purposeless,
as far as we can see, for any other end.

With Cattle there can be no doubt that extremely close inter-
breeding may be long carried on advantageously with respect to
external characters, and with no manifest evil as far as constitution
is concerned. The case of Bakewell's Longhorns, which were
closely interbred for a long period, has often been quoted; yet
Youatt says* the breed " had acquired a delicacy of constitution
inconsistent with common management," and " the propagation of
the species was not always certain.'^ But the Shorthorns offer the
most striking case of close interbreeding ; for instance, the famous
bull Favourite (who was himself the oftspring of a half-brother and
sister from Foljambe) was matched with his own danghter, grand-
daughter, and great-granddaughter ; so that the prodnce of this
last union, or the great-great-granddaughter, had 15-16ths, or
93*75 per cent, of the blood of Favourite in her veins. This cow
was matched with the bull "Wellington, having 62-5 per cent, of
Favourite blood in his veins, and produced Clarissa; Clarissa was
matched with the bull Lancaster, having 68"75 of the same blood,
and she yielded valuable offspring.^ Nevertheless CoUings, who
reared these animals, and was a strong advocate for close breeding,
once crossed his stock with a Galloway, and the cows from this
cross realised the highest prices. Bates's herd was esteemed the
most celebrated in the w^orld. For thirteen years he bred most
closely in and in ; but during the next seventeen years, though he
had the most exalted notion of the value of his own stock, he thrice
infused fresh blood into his herd : it is said that he did this, not to
improve the form of his animals, but on account of their lessened
fertility. Mr. Bates's own view, as given by a celebrated breeder,^

* ' Cattle,' p. 199.

* I give this on the authority of
Nathusius, ' Uebei* Shorthora Kind-
vieh,' 1857, s. 71 {see also ' Gardener's
Chronicle,' 1860, p. 270). But Mr.
J. Storer, a large breeder of cattle,
informs me that the parentage of
Clarissa is not well authenticated. In
the first vol. of the ' Herd Book,' she
was entered as having six descents
from Favourite, " which was a palpa-
ble mistake," and in all subsequent
editions she was spcsen of as having
only four descents. Mr. Storer doubts
even about the four, as no names of

the dams are given. Moreover, Cla-
rissa bore " only two bulls and one
heifer, and in the next generation her
progeny became extinct." Analogous
cases ot close interbreeding are given
in a pamphlet published by Mr. C.
Macknight and Dr. H. Madden, ' On
the True Principles of Breeding ; '
Melbourne, Australia, 18G5.

^ Mr. Willoughby Wood, in ' Gar-
dener's Chronicle,' 1855, p. 411 ; and
1860, p. 270. See the very clear
tables and pedigrees given in Nathu-
sius' ' Rindvieh/ s. 72-77.

Chap. XVn. EVIL FROM INTEEBREEDINQ. 97

was, that " to breed in-and-in from a bad stock was ruin and de-
vastation; yet that the practice may be safely followed within
certain limits when the parents so related are descended from first-
rate animals." We thus see that there has been much close inter-
breeding with Shorthorns ; but Nathusius, after the most careful
study of their pedigrees, says that he can find no instance of a
breeder who has strictly followed this practice during his whole
life. From this study and his own experience, he concludes that
close interbreeding is necessary to ennoble the stock ; but that in
effecting this the greatest care is necessary, on account of the ten-
dency to infertility and weakness. It may be added, that another
high authority "^ asserts that many more calves are born cripples
from Shorthorns than from other and less clostly interbred races
of cattle.

Although by carefully selecting the best animals (as Nature
effectually does by the law of battle) close interbreeding may be
long carried on with cattle, yet the good effects of a cross between
almost any two breeds is at once shown by the greater size and
vigour of the offspring; as Mr. Spooner writes to me, " crossing
distinct breeds certainly improves cattle for the butcher." Such
crossed animals are of course of no value to the breeder ; but they
have been raised during many years in several parts of England to
be slaughtered ; ^ and their merit is now so fully recognised, that
at fat-cattle shows a separate class has been formed fo'r their re-
ception. The best fat ox at the great show at Islington in 1862
was a crossed animal.

The half-wild cattle, which have been kept in British parks pro-
bably for 400 or 500 years, or even for a longer period, have been
advanced by Culley and others as a case of long continued inter-
breeding within the limits of the same herd without any consequent
injury. With respect to the cattle at Chillingham, the late Lord
Tankerville owned that they were bad breeders.^ The agent, Mr,
Hardy, estimates (in a letter to me, dated May, 1861) that in the
herd of about fifty the average number annually slaughtered, killed
by fighting, and dying, is about ten, or one in five. As the herd
is kept up to nearly the same average number, the annual rate of
increase must be likewise about one in five. The bulls, I may add,
engage in furious battles, of which battles the present Lord Tan-
kerville has given me a graphic description, so that there will
always be rigorous selection of the most vigorous males. I pro-
cured in 1855 from Mr. D. Gardner, agent to the Duke of Hamilton,

^ Mr. Wright, 'Journal of Royal bred his herd in-and-in for some yeais,

Agricult. See.,' vol. vii., 1846, p. 204. "lost in one season twenty -eight

Mr. J. Downing (a successful breeder calves solely from want of constibu-

of Shorthorns in h-eland) informs me tion."

that the raisers of the great families ^ Youatt on Cattle, p. 202.

of Shorthorns carefully conceal their ^ ' Report British Assoc, Zoolog.

sterility and want of constitution. He Sect.,' 1838.
adds that Mr. Bates, after he had

98 GOOD FEOM CROSSING. Chap. XVII.

the following account of the wild cattle kept in the Duke's park in
Lanarkshire, which is about 200 acres in extent. The number of
cattle -varies from sixty-five to eighty ; and the number annually
killed (I presume by all causes) is from eight to ten ; so that the
annual rate of increase can hardly be more than one in six. Now
in South America, where the herds are half-wild, and therefore
offer a nearly fair standard of comparison, according to Azara the
natural increase of the cattle on an estancia is from one-third to
one- fourth of the total number, or one in between three and four •
and this, no doubt, applies exclusively to adult animals fit for con-
sumption. Hence the half-wild British cattle which have long
interbred within the limits of the same herd are relatively far less
fertile. Although in an unenclosed country like Paraguay there
must be some crossing between the different herds, yet even there
the inhabitants believe that the occasional introduction of animals
from distant localities is necessary to prevent " degeneration in size
and diminution of fertility." ^^ The decrease in size from ancient
times in the Chillingham and Hamilton cattle must have been pro-
digious, for Professor Riitimeyer has shown that they are almost
certainly the descendants of the gigantic Bos primigenius. No
doubt this decrease in size may be largely attributed to less favour-
able conditions of life ; yet animals roaming over large j)arks, and
fed during severe winters, can hardly be considered as placed under
very unfavourable conditions.

AVith Shef:p there has often been long-continued interbreeding
within the limits of the same flock ; but whether the nearest rela-
tions have been matched so frequently as in the case of Shorthorn
cattle, I do not know. The Messrs. Brown during fifty years have
never infused fresh blood into their excellent flock of Leicesters.
Since 1810 Mr. Barford has acted on the same principle with the
Foscote flock. He asserts that half a century of experience has
convinced him that when two nearly related animals are quite
sound in constitution, in-and-in breeding does not induce dege-
neracy ; but he adds that he " does not pride himself on breeding
from the nearest affinities." In France the Naz flock has been bred
for sixty years without the introduction of a single strange ram.^^
Nevertheless, most great breeders of sheep have protested against
close interbreeding prolonged for too great a length of time.^'^ The
most celebrated of recent breeders, Jonas Webb, kept five separate
families to work on, thus " retaining the requisite distance of rela-
tionship between the sexes ;"^^ and what is probably of greater
importance, the separate flocks will have been exposed to somewhat
different conditions.

" Azai'a, ' Quadrupedes du Para- flock, * Bull, de la Soc. d'Acclimat.,'

guay,' torn. ii. pp. 354, 368. 1860, p. 477.

1^ For the case of the Messrs. '^ Nathusius, ' Rindvieh,' s. 65;

Brown, see 'Gard. Chronicle,' 1855, Youatt on Sheep, p. 495.

p. 26. For the Foscote flock, 'Gard. »3 'Gard. Chronicle,' 1861, p. 631
Chron.,' 1860, p. 416. For the Naz

Chap. XVII. EVIL FROM INTEEBREEDING. 99

Although by the aid of careful selection the near interbreeding
of sheep may be long continued without any manifest evil, yet it
has often been the practice with farmers to cross distinct breeds to
obtain animals for the butcher, which plainly shows that good of
some kind is derived from this practice. We have excellent evi-
dence on this head from Mr. S. Druce/* who gives in detail the
comparative numbers of four pure breeds and of a cross-breed
which can be supported on the same ground, and he gives their pro-
duce in fleece and carcase. A high authority, Mr. Pusey, sums up
the result in money value during an equal length of time, namely
(neglecting shilhngs), for Cotswolds 248?., for Leicesters 223?., for
Southdowns 204/., for Hampshire Downs 264/., and for the cross-
bred 293/. A former celebrated breeder, Lord Somerville, states
that his half-breeds from Eyelauds and Spanish sheep were larger
animals than either the pure Eyelands or pure Spanish sheep.
Mr. Spooner concludes his excellent Essay on Crossing by asserting
that there is a pecuniary advantage in judicious cross-breeding,
esjiecially when the male is larger than the female.'^

As some of our British parks are ancient, it occurred to me that
there must have been long-continued close interbreeding with the
fallow-deer (Cerv^Ks dama) kept in them ; but on inquiry I find that
it is a common practice to infuse new blood by procuring bucks
from other parks. Mr. Shirley ,^^ who has carefully studied the
management of deer, admits that in some parks there has been no
admixture of foreign blood from a time beyond the memory of man.
But he concludes " that in the end the constant breeding in-and-in
" is sure to tell to the disadvantage of the whole herd, though it
" may take a very long time to prove it ; moreover, when we find,
" as is very constantly the case, that the introduction of fresh blood
" has been of the very greatest use to deer, both by improving their
" size and appearance, and particularly by being of service in re-
"■ moving the taint of ' rickback,' if not of other diseases, to which
" deer are sometimes subject when the blood has not been changed,
" there can, I think, be no doubt but that a judicious cross with a
" good stock is of the greatest consequence, and is indeed essential,
" sooner or later, to the prosperity of every well-ordered park."

Mr. Meynell's famous foxhounds have been adduced, as showing
that no ill effects follow from close interbreeding; and Sir J,
Sebright ascertained from him that he frequently bred from father
and daughter, mother and son, and sometimes even from brothers
and sisters. With greyhounds also there has been much close
interbreeding, but the best breeders agree that it may be carried

'* 'Journal R. Agricult. Soc.,' vol. ii. See also an excellent paper on

xiv., 1853, p. 212. the same subjectin ' Gard. Chronicle,'

^^ Lord Somerville, 'Facts on 1860, p. 321, by Mr. Charles Howard.
Sheep and Husbandry,' p. 6. Mr. '^ ' Some Account of English De&l

Spooner, in ' Journal of Royal Agri- Parks,' by Evelyn P. Shirley, 1867.
cult. Soc. of England,* vol. xx. part

100

GOOD FROM CKOSSING.

Chap. XVII

too far.^"^ But Sir J. Sebright, declares/^ that by breeding in-and-in,
by which he meaDS matching brothers and sisters, he has actually
Been the offspring of strong spaniels degenerate into weak and
diminutive lapdogs. The Kev. W. D. Fox has communicated to
me the case of a small lot of bloodhounds, long kept in the same
family, which had become vei-y bad breeders, and nearly all had a
bony enlargement in the tail. A single cross with a distinct strain
of bloodhounds restored their fertility, and drove away the tendency
to malformation in the tail I have heard the particulars of an-
other case with bloodhounds, in which the female had to be held to
the male. Considering how rapid is the natural increase of the
dog, it is difficult to understand the large price of all highly im-
proved breeds^ which almost implies long-continued close inter-
breeding, except on the belief that this process lessens fertility
and increases liability to distemper and other diseases. A high
authority, Mr. Scrope, attributes the rarity and deterioration in
size of the Scotch deerhound (the few individuals formerly existing
throughout the country being all related) in large part to close
interbreeding.

With all highly-bred animals there is more or less difficulty in
getting them to procreate quickly, and all suffer much from delicacy
of constitution. A great judge of rabbits ^^ says, "the long-eared
does are often too highly bred or forced in their youth to be of much
value as breeders, often turning out barren or bad mothers."
They often desert their young, so that it is necessary to have
nurse-rabbits, but I do not pretend to attribute all these evil results
to close interbreeding.^*'

With respect to Figs there is more unanimity amongst breeders
on the evil effects of close interbreeding than, perhaps, with any
other large animal. Mr. Druce, a great and successful breeder of
the Improved Oxfordshires (a crossed race), writes, "without a
change of boars of a different tribe, but of the same breed, constitu-
tion cannot be preserved." Mr. Fisher Hobbs, the raiser of the

17 Stonehenge, ' The Dog,' 1867, pp.
175-188.

1* 'The Alt of Improving the
Breed,' &c., p. 13. With respect to
Scotch deerhounds, see Scrope's 'Art
of Deer Stalking,' pp. 350-353.

19 'Cottage Gardener,' 1861, p. 327.

'^" Mr. Huth gives (' The Marriage
of Near Kin,' 1875, p. 302) from the
' Bulletin de I'Acad. R. de Med, dc
Belgique' (vol. ix., 1866, pp. 287,
305), several statements made by a
M. Legrain with respect to crossing
brother and sister rabbits for five or
six successive generations with no
consequent evil results. I was so
much surprised at thih account, and

at M. Legrain's invariable success
in his experiments, that I wrote to a
distinguished naturalist in Belsfium
to inquire whether M. Legrain was a
trustworthy observer. In answer, I
have heard that, as doubts were ex-
pressed about the authenticity of these
experiments, a commission of inquiry
was appointed, and that at a suc-
ceeding meeting of the Society (' Bull,
de I'Acad. E. de Med. de Belgique,'
1867, 3rd series. Tome 1, No. i to
5), Dr. Crocq repoj. ied " qu'il etait
materiellement impossible que M. Le-
grain ait fait les experiences qu'il
annonce." To this public accusation
110 satisfactory answer was made.

CiiAP. XYII. EVIL FEOM INTEKBEEEDING. lOl

celebrated Improved Essex breed, divided his stock into three
separate families, by which means he maintained the breed for
more than twenty years, *'by judicious selection from the three
distinct families "'^^ Lord Western was the first importer of a
Neapolitan boar and sow. "From this pair he bred in-and-in,
until the breed was in danger of becoming extinct, a sure result
(as Mr. Sidney remarks) of in-and-in breeding." Lord Western
then crossed his Neapolitan pigs with the old Essex, and made the
first great step towards the Improved Essex breed. Here is a more
interesting case. Mr. J.Wright, well known as a breeder, crossed ^^
the same boar with the daughter, granddaughter, and great-grand-
daughter, and so on for seven generations. The result was, that
in many instances the offsiDring failed to breed; in others they
produced few that lived ; and of the latter many were idiotic,
without sense, even to suck, and when attempting to move could
not walk straight. Now it deserves especial notice, that the two
last sows produced by this long course of interbreeding were sent
to other boars, and they bore several litters of healthy pigs. The
best sow in external appearance produced during the whole seven
generations was one in the last stage of descent; but the litter
consisted of this one sow. She would not breed to her sire, yet
bred at the first trial to a stranger in blood. So that, in Mr.
Wright's case, long-continued and extremely close interbreeding
did not affect the external form or merit of the young ; but with
many of them the general constitution and mental powers, and
especially the reproductive functions, were seriously afiected.

Nathusius gives ^^ an analogous and even more striking case : he
imported from England a pregnant sow of the large Yorkshire
•breed, and bred the product closely in-and-in for three generations :
the result was unfavourable, as the young were weak in constitution,
with impaired fertility. One of the latest sows, which he esteemed
a good animal, produced, when paired with her ow^n uncle (who was
known to be productive with sows of other breeds), a litter of six,
and a second time a litter of only five weak young pigs. He then
paired this sow with a boar of a small black breed, which he had
likewise imported from England ; this boar, when matched with
sows of his own breed, produced from seven to nine young. Now,
the sow of the large breed, which was so unproductive when paired
with her own uncle, yielded to the small black boar, in the first
litter twenty-one, and in the second litter eighteen young pigs ; so
that in one year she produced thirty-nine fine young animals !

As in the case of several other animals already mentioned, even

^^ Sidney's edit, of ' Youatt on the Col. Le Couteur, who has done so

Pig,' 1860, p. 30; p. 33, quotation much for the agriculture of Jersey,

from Mr. Druce ; p. 29, on Lord writes to me that from possessing a

Western's case. fine breed of pigs he bred them very

^" ' Journal of Royal Agricult. Soc. closely, twice pairing brothers and

of England,' 1846, vol. vii. p. 205. sisters, but nearly all the young had

2^ ' Ucber Rindvieh,' kc, s. 78. fits and died suddenly.

102

GOOD FROM CROSSING.

CiiAP. XVII.

when no injury is perceptible from moderately close interbreeding,
y^et, to quote the words of Mr. Coate (who five times won the annual
gold medal of the Smithfield Club Show for the best pen of pigs),
" Crosses answer well for profit to the farmer, as you get more
" constitution and quicker growth ; but for me, who sell a great
" number of pigs for breeding purposes, I find it will not do, as
it requires many years to get anything like purity of blood

" again." ^^

Almost all the animals as y^t mentioned are gregarious,
and the males must frequently pair with their own daughters,
for they expel the young males as well as all intruders, until
forced by old age and loss of strength to yield to some stronger
male. It is therefore not improbable that gregarious animals
may have been rendered less susceptible than non-social
species to the evil consequences of close interbreeding, so
that they may be enabled to live in herds without injury
to their offspring. Unfortunately we do not know whether
an animal like the cat, which is not gregarious, would suffer
from close interbreeding in a greater degree than our other
domesticated animals. But the jDig is not, as far as I can
discover, strictly gregarious, and we have seen that it appears
eminently liable to the evil effects of close interbreeding.
Mr. Huth, in the case of the pig, attributes (p. 285) these
effects to their having been " cultivated most for their fat," or*
to the selected individuals having had a weak constitution ;
but we must remember that it is great breeders who have
brought forward the above cases, and who are far more
familiar than ordinary men can be, with the causes which are
likely to interfere with the fertility of their animals.

The effects of close interbreeding in the case of man is a
difficult subject, on which 1 will say but little. It has been
discussed by various authors under many points of view.^^

2^ Sidney (.n the Pig, p. 36. See
also note, p. 34. Also Richardson un
the Pig, 1847, p. 26.

** Dr. Dally has published an excel-
lent article (translated in the ' Anthro-
polog. Review/ May, 1864, p. 65),
criticising all writers who b.ave main-
tained that evil follows from con-
sanguineous marriages. No doubt on
this side of the question many advo-

cates have injured their cause by in-
accuracies : thus it has been stated
(Devay, ' Du Danger des Manages,*
&c., 1862, p. 141) that the marriages
ot" cousins have been prohibited by
the legishiture of Ohio ; but I have
been assured, in answer to inquiries
made in the L'nited States, that this
statement is a mere fable.

Chap. XYIl.

EVIL FROM INTERBREEDING.

103

Mr. Tylor ^^ has sliown that with widely different races in
the most distant quarters of the world, marriages between
relations — even between distant relations — have been strictly
prohibited. There are, however, many exceptions to the
rule, which are fully given by Mr. Huth.^^ It is a curious
problem how these prohibitions arose during early and
barbarous times. Mr. Tyler is inclined to attribute them to
the evil effects of consanguineous marriages having been ob-
served ; and he ingeniously attempts to explain some apparent,
anomalies in the prohibition not extending equally to the
relations on the male and female side. He admits, however,
that other causes, such as the extension of friendly alliances,
may have come into play. Mr. W. Adam, on the other hand,
concludes that related marriages are prohibited and viewed
with repugnance, from the confusion which would thus arise
in the descent of property, and from other still more recondite
reasons. But I cannot accept these views, seeing that incest
is held in abhorrence by savages such as those of Australia
and South America,^^ who have no property to bequeath, or
fine moral feelings to confuse, and who are not likely to
reflect on distant evils to their progeny. According to jMr.
Huth the feeling is the indirect result of exogamy, inasmuch
as when this practice ceased in any tribe and it became
endogamous, so that marriages were strictly confined to the
same tribe, it is not unlikely that a vestige of the former
practice would still be retained, so that closely-related
marriages would be prohibited. With respect to exogamy
itself Mr. MacLennan believes that it arose from a scarcity
of women, owing to female infanticide, aided perhaps by
other causes.

It has been clearly shown b}^ Mr. Huth that there is no

26 See his interesting work on the
' Early History of Man,' 1865, chap. x.

-' 'The Marriage of Near Kin,'
1875. The evidence given by INlr.
Huth would, I think, have been even
more valuable than it is on this and
some other points, if he had referred
solely to the works of men who had
long resided in each country referred
to, and who showed that they possessed

ju.dgment and caution. See also Mr.
\V. Adam, ' On Consanguinity in Mar-
riaoe ' in the ' Fortnightly Review,'
1865, p. 710. Also Hofacker, ' Ueber
die Eigenschaften,' &c., 18J8.

2^ Sir G. Grey's ' Journal of Expe-
ditions into Australia,' vol. ii. ji. 24r;3 ;
and Dobrizhotfer, ' On the Ablpones oi
South America.'

104 GOOD FROM CROSSING. Chap. XYU.

instinctive feeling in man against incest any more than in
gregarious animals. We know also liow readily an}' prejudice
or feeling may rise to abhorrence, as shown by Hindus in
regard to objects causing delilement. Although there seems
to be no strong inherited feeling in mankind against incest,
it seems possible that men during primeval times may have
been more excited by strange females than by those with
whom they habitually lived ; in the same manner as accord-
•ing to Mr. Cupples,^^ male deerhounds are inclined towards
strange females, while the females prefer dogs with whom
they have associated. If any such feeling formerly existed
in man, this would have led to a preference for marriages
beyond the nearest kin, and might have been strengthened
by the offspring of such marriages surviving in greater
numbers, as analogy would lead us to believe would have
occurred.

AVhether consanguineous marriages, such as are permitted
in civilised nations, and which would not be considered as
close interbreeding in the case of our domesticated animals,
cause any injury will never be known with certainty until a
census is taken with this object in view. My son, George
Darwin, has done what is possible at present by a statistical
investigation,^*^ and he has come to the conclusion, from his
own researches and those of Dr. Mitchell, that the evidence as
to any evil thus caused is conflicting, but on the whole points
to the evil being very small.

Birds. — III the case of the Fowl a whole array of authorities
could be given against too close interbreeding. Sir J. Sebright
positively asserts that he made many trials, and that his fowls,
when thus treated, became long in the legs, small in the body, and
bad breeders.^' He produced the famous Sebright Bantams by
complicated crosses, and by breeding in-and-in ; and since his time
there has been much close interbreeding with these animals ; and
they are now notoriously bad breeders. 1 have seen Silver Bantams,
directly descended from his stock, which had become almost as
barren as hybrids; for not a single chicken had been that year

29 'Descent of Man, 2Dd. edit p. Review.' June, 1875.
524. ^' ' The Art of Irnprov.'ag the

^° 'Journal of Statistical Soc' June, Breed/ p. 13.
1875, p. 153 : and ' Fortnightly

Chap. XYIL

EVIL FROM INTEEBEEEDING.

105

(f

(I

((

hatclied fi'om two full nests of eggs. Mr. Hewitt says that with
these Bantams the sterility of the male stands, with rare exceptions,
in the closest relation with their loss of certain secondary male
characters : he adds, " I have noticed, as a general rule, that even
" the slightest deviation from feminine character in the tail of the
" male Sebright — say the elongation by only half an inch of the two
" principal tail feathers — brmgs with it improved probability of
" increased fertility." ^^

Mr. Wright states ^^ that Mr. Clark, "whose fighting-cocks were
" so notoiious, continued to breed from his own kind till tbey lost
" their disposition to fight, but stood to be cut up without making
*•' any resistance, and were so reduced in size as to be under those
weights required for the best prizes; but on obtaining a cross
from Mr. Leighton, they again resumed their former courage and
weight." It should be borne in mind that game-cocks before they
fought were always weighed, so that nothing was left to the imagi-
nation about any reduction or increase of weight. Mr. Clark does
not seem to have bred from brothers and sisters, which is the most
injurious kind of union; and he found, after repeated trials, that
there was a greater reduction in weight in the young from a
father paired with his daughter, than from a mother with her son
I may add that Mr. Eyton, of Eyton, the well-known ornithologist,
who is a large breeder of Grey Dorkings, informs me that they
certainly diminish in size, and become less prolific, unless a cross
with another strain is occasionally obtained. So it is with Malays,
according to Mr. Hewitt, as far as size is concerned.^*

An experienced writer ^^ remarks that the same amateur, as
is well known, seldom long maintains the suiDeriority of his birds ;
and this, he adds, undoubtedly is due to all his stock " being
of the same blood;" hence it is indispensable that he should
occasionally procure a bird of another strain. But this is not
necessary with those who keep a stock of fowls at different stations.
Thus, Mr. Ballance, who has bred Malays for thirty years, and
has won more prizes with these birds than any other fancier
in England, says that breeding in-and-in does not necessarily
cause deterioration ; " but all depends upon how this is managed."
" My plan has been to keep about five or six distinct runs, and
" to rear about two hundred or three hundred chickens each year,
" and select the best birds from each run for crossing. I thus
" secure sutficient crossing to prevent deterioration." ^^

32 < The Poultry Book,' by W. B.
Tegetmeier, 186'?, p. 245.

^^ ' Journal Royal Agricult. Soc.,'
1846, vol. vii. p. 205 ; see also Fergu-
son on the Fowl, pp. 83, 317 ; see also
' The Poultry Book,' by Tegetmeier,
1866, p. 135, with respect to the
extent to which cock-fighters found
that they could venture to breed in-

and-in, viz., occasionally a hen with
her own son ; " but they were cautious
not to repeat the in-and-in breeding.'*

3< 'The Poultry Book,' by W. B.
Tegetmeier, 1866, p. 79.

3^ 'The Poultry Chronicle,' 1854,
vol. i. p. 43.

36 ' The Poultry Book,' by W. R
Tegetmeier, 1866, p. 79.

106 GOOD FROM CEOSSING. Chap. XVII-

We thus see that there is almost complete ■unanimity with
poultry-breeders that, when fowls are kept at the same jDlaoe,
evil quickly follows from interbreeding carried on to an extent
which would be disregarded in the case of most quadrupeds.
Moreover, it is a generally received opinion that cross-bred
chickens are the hardiest and most easily reared.^^ Mr. Tegetmeier,
who has carefully attended to poultry of all breeds, says^^ that
Dorking hens, allowed to run with Houdan or Crevecoeur cocks,
*' produce in the early spring chickens that for size, hardihood,
" early maturity, and fitness lor the market, surpass those of any
*' pure breed that we have ever raised." Mr. Hewitt gives it as
a general rule with fowls, that crossing the breed increases their
size. He makes this remark after stating that hybrids from
the pheasant and fowl are consideralily larger than either progenitor :
so again, hybrids from the male golden pheasant and female common
pheasant "are of far larger size than either parent-bird."^^ To
this subject of the increased size of hybrids I shall presently return.

With Pigeonf^, breeders are unanimous, as previously stated,
that it is absolutely indispensable, notwithstanding the trouble
and expense thus caused, occasionally to cross their much-prized
birds with individuals of another strain, but belonging, of course,
to the same variety. It deserves notice that, when size is one
of the desired characters, as with pouters,'*" the evil effects of close
interbreeding are much sooner perceived than when small birds,
such as short-faced tumblers, are valued. The extreme delicacy
of the high fancy breeds, such as these tumblers and improved
English carriers, is remarkable; they are liable to many diseases,
and often die in the egg or during the first moult ; and their eggs
have generally to be hatched under foster-mothers. Although
these highly-prized birds have invariably been subjected to much
close interbreeding, yet their extreme delicacy of constitution
cannot perhaps bo thus fully explained. Mr. Yarrell informed me
that 8ir J. Sebright continued closely interbreeding some owl-
pigeons, until from their extreme sterility he as nearly as possible
lost the whole family. Mr. Brent" tried to raise a breed of
trumpeters, by crossing a common pigeon, and recrossing the
daughter, granddaughter, great-granddaughter, and great-great-
granddaughter, with the same male trumpeter, until he obtained
a bird with ^f of trumpeter's blood; but then the experiment
failed, for "breeding so close stopped reproduction." The ex-
perienced Neumeister ^^ also asserts that the offspring from dove-
cotes and various other breeds are "generally very fertile and

37 * The Poultry Chronicle,' vol. i. ^° ' A Treatise on Fancy Pigeons,'

p. 89. by J. M. Eaton, p. 56.

28 <The Poultry Book,' 1866, p. *^ ' The Pigeon Book,' p. 46.

210. ""^ ' Das Ganze der Taubenzucht,'

39 Ibid. 1866, p. 167 ; and ' Poultry 1837, s. 18.
Chronicle,' vol. lii., 1855, p. 15.

.Chap. XVIL EVIL FROM INTEEBKEEDINa. 107

hardy birds : " so again, ]\I]\I. Boitard and Corbie/^ after forty-five
years' experience, recommend persons to cross their breeds for
amusement ; for, if they fail to make interesting birds, they will
BTicceed nnder an economical point of view, " as it is found that
mongrels are more fertile than pigeons of pure race."

I will refer only to one other animal, namely, the Hive-bee,
because a distinguished entomologist has advanced this as a case
of inevitable close interbreeding. As the hive is tenanted by a
single female, it might have been thought that her male and
female offspring would always have bred together, more especially
as bees of different hives are hostile to each other ; a strange worker
being almost always attacked when trying to enter another hive.
But Mr. Tegetmeier has shown ^* that this instinct does not apply
to drones, which are permitted to enter any hive ; so that there
is no a priori improbability of a queen receiving a foreign drone.
The fact of the union invariably and necessarily taking place
on the wing, during the queen's nuptial flight, seems to be a special
provision against continued interbreeding. However this may be,
experience has shown, since the introduction of the yellow-banded
Ligurian race into Germany and England, that bees freely cross :
Mr. Woodbury, who introduced Ligurian bees into Devonshire,
found during a single season that three stocks, at distances of from
one to two miles from his hives, were crossed by his drones.
In one case the Ligurian drones must have flown over the city
of Exeter, and over several intermediate hives. On another
occasion several common black queens were crossed by Ligurian
drones at a distance of from one to three and a half miles.*^

Plants.

When a single plant of a new species is introduced into any
country, if propagated by seed, many individuals will soon be
raised, so that if the proper insects be present there will be crossing.
With newly-introduced trees or other plants not propagated
by seed we are not here concerned. With old-established plants
it is an almost universal practice occasionally to make exchanges
of seed, by which means individuals which have been exposed
to different conditions of life, — and this, as we have seen with
animals, diminishes the evil from close interbreeding, — will
occasionally be introduced into each district.

With respect to individuals belonging to the same sub-variety,
Gartner, whose accuracy and experience exceeded that of all other
observers, states ^^ that he has many times observed good effects
from this step, especially with exotic genera, of which the fertility
is somewhat impaired, such as Passiflora, Lobelia, Euchsia.

<3 ' Les Pigeons,' 1824, p. 35. pp. 39, 77, 158 ; and 1864, p. 206.
** ' Proc. Entomolog. Soc.,' Aug. *^ ' Beitrage zur Kenntniss der

Sth, 1860, p. 126. Befruchtung,' 1844, s. 366.
" ' Journal of Horticulture,' 1S61,

108 GOOD FROM CROSSING. Chap. XVII.

Herbert also says/"^ " I am inclined to think that I have derived
"advantage from impregnating the flower from which I wished
" to obtain seed with pollen from another individual of the same
" variety, or at least from another flower, rather than with its
" own." Again, Professor Lecoq ascertained that crossed offsj)ring
are more vigorous and robust than their parents.^^

General statements of this kind, however, can seldom be fully
trusted : I therefore began a long series of experiments, continued
for about ten years, which will I think conclusively show the
good effects of crossing two distinct plants of the same variety,
and the evil effects of long-continued self- fertilisation. A clear
light will thus be thrown on such questions, as why flowers are
almost invariably constructed so as to permit, or favour, or necessi-
tate the union of two individuals. We shall clearly understand
why monoecious and dioecious, — why dichogamous, dimorphic and
trimorphic plants exist, and many other such cases. I intend soon
to publish an account of these experiments, and I can here give only
a few cases in illustration. The plan which I followed was to grow
plants in the same pot, or in pots of the same size, or close together in
the open ground ; carefully to exclude insects ; and then to fertilise
some of the flowers with pollen from the same flower, and others
on the same plant with pollen from a distinct but adjoining plant.
Ill many of these experiments, the crossed plants yielded much
more seed than the self-fertilised plants ; and I have never seen
the reversed case. The self-fertilised and crossed seeds thus
obtained were allowed to germinate in the same glass vessel on
damp sand ; and as the seeds germinated, they were planted
in pairs on opposite sides of the same pot, with a superficial
partition between them, and were placed so as to be equally ex-
posed to the light. In other cases the self-fertilised and crossed
seeds were simply sown on opposite sides of the same small pot.
I have, in short, followed different plans, but in every case have
taken all the precautions which I could think of, so that the two
lots should be equally favoured. The growth of the plants raised
from the crossed and self-fertilised seed, were carefully observed from
their germination to maturity, in species belonging to fifty-two
genera; and the difference in their growth, and in withstanding
unfavourable conditions, was in most cases manifest and strongly
marked. It is of importance that the two lots of seed should be
sown or planted on opposite sides of the same pot, so that the seed-
lings may struggle against each other; for if sown separately in
ample and good soil, there is often but little difference in their growth.

I will briefly describe two of the first cases observed by me.
Six crossed and six self-fertilised seeds of Jpomoea purpurea, from
plants treated in the manner above described, were planted as soon
as they had germinated, in pairs on opposite sides of two pots,
and rods of equal thickness were given them to twine up. Five

' Amaryllidaceae,' p. 371. " 'De la Fecondatioo,' 2n'l edit., 1862, p. 79.

Chap. XVll. EVIL FROM INTERBREEDING. 109

of the crossed plants grew from the first more quickly than the
opposed self-fertilised plants ; the sixth, however, was weakly and
was for a time beaten, but at last its sounder constitution jirevailed
and it shot ahead of its antagonist. As soon as each crossed plant
reached the top of its seven-foot rod its fellow was measured, and
the result was that, when the crossed plants were seven feet high
the self- fertilised had attained the average height of only five feet
four and a half inches. The crossed plants flowered a little before,
and more profusely than the self-fertilised plants. On opposite
sides of another small pot a large number of crossed and self-
fertilised seeds were sown, so that they had to struggle for bare
existence ; a single rod was given to each lot : here again the crossed
plants showed from the first their advantage ; they never quite
reached the summit of the seven-foot rod, but relatively to the
self- fertilised plants their average height was as seven feet to five
feet two inches. The experiment was repeated during several
succeeding generations, treated in exactly the same manner, and
with nearly the same result. In the second generation, the crossed
plants, which were again crossed, produced 121 seed - capsules,
whilst the self- fertilised, again self-fertilised, produced only 84
capsules.

Some flowers of the Mimuhis Intevs were fertilised with their
own pollen, and others were crossed with pollen from distinct plants
gTOwing in the same pot. The seeds were thickly sown on
opposite sides of a pot. The seedlings were at first equal in
height; but when the young crossed plants were half an inch,
the self-fertilised plants were only a quarter of an inch high.
But this degree of inequality did not last, for, when the crossed
plants were four and a half inches high, the self-fertilised were
three inches, and they retained the same relative difference till
their growth was complete. The crossed plants looked far more
vigorous than the uncrossed, and flowered before them ; they
produced also a far greater number of capsules. As in the former
case, the experiment was repeated during several succeeding gene-
rations. Had I not watched these plants of Mimulus and Ipomoea
during their whole growth, I could not have believed it possible,
that a difference apparently so slight as that of the pollen being taken
from the same flower, or from a distinct plant growing in the same
pot, could have made so wonderful a difference in the gi'owth and
vigour of the plants thus produced. This, under a physiological
point of view, is a most remarkable phenomenon.

With respect to the benefit derived from crossing distinct
varieties, plenty of evidence has been published. Sageret^^ re-
peatedly speaks in strong terms of the vigour of melons raised by
crossing different varieties, and adds that they are more easily
fertilised than common melons^ and produce numerous good seed.

*' • Memoire sur les Cucurbitacees,' pp. 36, 28, 30.

27

110 GOOD FROM CEOSSING. nuAP. XVII.

Here follows the ondence of an English gardener :°° "I have this
" summer met Avith better success in my cultivation of melons, in
" an unprotected state, from the seeds of hybrids (i.e. mongrels)
" obtained by cross impregnation, than with old varieties. The
" offspring of three different hybridisations (one more esj)ecially, of
" which the parents were the two most dissimilar varieties I could
" select) each yielded more ample and finer produce than any one
" of between twenty and thirty established varieties."

Andrew Knight^^ believed that his seedlings from crossed varieties
of the apple exhibited increased vigour and luxuriance; and M,
ChevreuP- alludes to the extreme vigour of some of the crossed
fruit-trees raised by Sageret.

By crossing reciprocally the tallest and shortest peas. Knight"'^
says : " I had in this experiment a striking instance of the
" stimulative effects of crossing the breeds; for the smallest variety,
" whose height rarely exceeded two feet, was increased to six feet ;
*' whilst the height of the large and luxuriant kind was very little
" diminished." Mr. Laxton gave me seed-peas produced from
crosses between four distinct kinds ; and the plants thus raised were
extraordinarily vigorous, being in each case from one to two or three
feet taller than tbe parent-forms growing close alongside them.

Wiegmann^* made many crosses between several varieties of
cabbage; and he speaks with astonishment of the vigour and
height of the mongrels, which excited the amazement of all the
gardeners who beheld them. Mr. Chaundy raised a great number
of mongrels by planting together six distinct varieties of cabbage.
These mongrels displayed an infinite diversity of character ; " But
" the most remarkable circumstance was, that, while all the other
" cabbages and borecoles in the nursery were destroyed by a severe
" winter, these hybrids were little injured, and supplied the kitchen
" when there was no other cabbage to be had."

Mr. Maund exhibited before the Eoyal Agi'icultural Society ^^
specimens of crossed wheat, together with their parent varieties ;
and the editor states that they were intermediate in character,
" united with that greater vigour of growth, which it appears, in
" the vegetable as in the animal world, is the result of a first cross."
Knight also crossed several varieties of wheat,''^^ and he says " that
" in the years 1795 and 1796, when almost the whole crop of corn
" in the island was blighted, the varieties thus obtained, and these
" only, escaped in this neighbourhood, though sown in several
" different soils and situations."

^* Loudon's ' Gard. Mag.,' vol. viii., ^'^ ' Ueber die Bastarderzeticrung,'

1832, p. 52. 1828, s. 32, 33. For Mr. Chauruly's

*^ ' Tx-ausact. Hort. Soc.,' vol. i. p. case, see Loudon's ' Gard. Mag.' voL

25. vii. 1831, p. 69G.

'" ' Annal. des Sc. Nat.,' 3rd series, " ' Gardener's Chron.,' 1846, p

Bot., torn. vi. p. 189. 601.

53 ' Philosophical Transactions,' *^ ' Philosoph. Transact.,' 1799, p

1799, p. 200. 201.

Chap. XYII. EVIL FKOM INTEEBEEEDING. Ill

Here is a remarkable case : M. Clotzsch'^'^ crossed Pinus sylvestris
and nigricans, Quercus robur and pedunciilata, Alnus glutinosa and
incana, Ulmus campestris and effusa ; and the cross-fertilised seeds,
as well as seeds of the pure parent-trees, were all sown at the same
time and in the same place. The result was, that after an interyal of
eight years, the hybrids were one-third taller than the pure trees !

The facts above given refer to undoubted varieties, excepting
the trees crossed by Clotzsch, which are ranked by various botanists
as strongly-marked races, sub-species, or sj^ecies. That true
hybrids raised from entirely distinct species, though they lose in
fertility, often gain in size and constitutional vigour, is certain. It
would be superfluous to quote any facts; for all experimenters,
Kolreuter, Gartner, Herbert, Sageret, Lecoq, and Naudin, have
been struck with the wonderful vigour, height, size, tenacity of life,
precocity, and hardiness of their hybrid productions. Gartner^*
sums up his conviction on this head in the strongest terms. Kol-
reuter^^ gives numerous precise measurements of the weight and
height of his hybrids in his comparison with measurements of both
parent-forms ; and speaks with astonishment of their statura por~
" tentosa" their "ambitus vastissimus ac uUitudo vulde conspicua."
Some exceptions to the rule in the case of very sterile hybrids have,
however, been noticed by Gartner and Herbert; but the most
striking exceptions are given by Max Wichura,*^^ who found that
hybrid willows were generally tender in constitution, dwarf, and
short-lived.

Kolreuter explains the vast increase in the size of the roots,
stems, &c., of his hybrids, as the result of a sort of compensation
due to their sterility, in the same way as many emasculated
animals are larger than the perfect males. This view seems at first
sight extremely probable, and has been accepted by various authors ;'^^
but Gartner''^ has well remarked that there is much difficulty in
fully admitting it ; for with many hybrids there is no parallelism
between the degree of their sterility and their increased size and
vigour. The most striking instances of luxuriant gi'owth have been
observed with hybrids which were not sterile in any extreme
degree. In the genus Mirabilis, certain hybrids are unusually
fertile, and their extraordinary luxuriance of growth, together with

5" Quoted in 'Bull. Bot. Soc. ^o < Die Bastardbefruchtung,' &c.,

France,' vol ii., 1855, p. 327. 18(35, s. 31, 41, 42.

*^ Gai'tner, ' Bastarderzeugung,' s. ^' Max Wichura fully accepts this

259, 518, 526 et seq. view (' Bastardbefrucbtung,' s. 43),

^^ ' Fortsetzung,' 1763, s. 29 ; as does the Rev. M. J. Berkeley, in

* Dritte Fortsetzung,' s. 44, 96 ; ' Act. ' Journal of Hort. Soc.,' Jan. 1866,

Acad. St. Petersbux-g,' 1782, part ii., p. 70.

p. 251; 'Nova Acta,' 1793, pp. 391, ^^ 'Bastarderzeugung,' s. 394, 526,

394; 'Nova Acta,' 1795, pp. 316, 528.
323.

112 GOOD FEOM CROSSING. Chap. XVIL

their enormous roots/^ have been transmitted to tlieir progeny.
The result in all cases is probably in part cine to the saving of
nutriment and vital force through the sexual organs acting imper-
fectly or not at all, but more especially to the general law of good
being derived from a cross. For it deserves especial attention that
mongrel animals and plants, which are so far from being sterile that
their fertility is often actually augmented, have, as jDreviously
shown, their size, hardiness, and constitutional vigour generally
increased. It is not a little remarkable that an accession of vigour
and size should thus arise under the opi^osite contingencies of
increased and diminished fertility.

It is a perfectly well ascertained fact^* that hybrids invariably
breed with either pure parent, and not rarely with a distinct species,
more readily than with one another. Herbert is inclined to explain
even this fact by the advantage derived from a cross ; but Gartner
more justly accounts for it by the pollen of the hybrid, and
probably its ovules, being in some degree vitiated, whereas the
pollen and ovules of both pure parents and of any third species are
sound. Nevertheless, there are some well-ascertained and "re-
markable facts, which, as we shall presently see, show that a cross
by itself undoubtedly tends to increase or re-establish the fertility
of hybrids.

The same law, namely, that the crossed offspring both of varieties
and species are larger than the parent-forms, holds good in the
most striking manner with hybrid animals as well as with mongrels.
Mr. Bartlett, who has had such large experience says, " Among all
" hybrids of vertebrated animals there is a marked increase of size."
He then enumerates many cases with mammals, including monkeys,
and with various families of birds.^^

On certain Hermaplirodite Plants ivliich, eitlier normally or abnor-
mally, require to he fertilised hy pollen from a distinct individual
or species.

The facts now to be given diifer from the foregoing, as
self-sterility is not here the result of long-continued close
interbreeding. These facts are, however, connected with our
present subject, because a cross with a distinct individual is
shown to be either necessary or advantageous. Dimorphic
and trimorphic plants, though they are hermaphrodites, must
be reciprocally crossed, one set of forms by the other, in order
to be fully fertile, and in some cases to be fertile in any degree.

. «3 Kolreuter, < Nova Acta,' 1795, 430.

p. 316. «^ Quoted by Dr. Murie, iu ' Proc.

** Gartuer, ' Bastarderzeugung,' s. Zoolog. Soc.,' 1870, p. 40.

Chap. XYIL EVIL FROM INTEEBREEDIXG. 113

But I should not have noticed fhese plants, had it not been
for the following cases given by Dr. Hildebrand :^^ —

Primula sinensis is a reciprocally dimorphic species: Dr. Hilde-
brand fertilised twenty-eight fioAvers of both forms, each by pollen of
the other form, and obtained the full number of capsules containing
on an average 42"7 seed per capsule ; here we have complete and
normal fertility. He then fertilised forty-two flowers of both forms
with pollen of the same form, but taken from a distinct j^lant, and
all produced capsules containing on an average only 19*6 seed.
Lastly, and here we come to our more immediate point, he fertilised
forty-eight flowers of both forms with pollen of the same form and
taken from the same flower, and now he obtained only thirty-two
capsules, and these contained on an average 18'6 seed, or one less
per capsule than in the former case. So that, with these illegitimate
unions, the act of impregnation is less assured, and the fertility
slightly less, wdien the pollen and ovules belong to the same flower,
than w^hen belonging to two distinct individuals of the same form.
Dr. Hildebrand has recently made analogous experiments on the
long -styled form of Oxalis rosea, with the same result.'^^

It has recently been discovered that certain plants, whilst
growing in their native country under natural conditions,
cannot be fertilised with pollen from the same plant. They
are sometimes so utterly self-impotent, that, though they can
readily be fertilised by the pollen of a distinct species or
even distinct genus, j^et, wonderful as is the fact, they never
produce a single seed by their own pollen. In some cases,
moreover, the plant's own pollen and stigma mutually act on
each other in a deleterious manner. Most of the facts to be
given relate to orchids, but I will commence with a plant
belonging to a widely different family.

Sixty-three flowers of Corijdalis cava, borne on distinct plants,
were fertilised by Dr. Hildebrand '^^ witli pollen from other plants of
the same species; and tifty-eight capsules were obtained, including
on an average 4*5 seed in each. He then fertilised sixteen flowers
l^roduced by the same raceme, one with another, but obtained only
three capsules, one of which alone contained any good seeds,
namely, two in number. Lastly, he fertilised twenty-seven flowers,
each with its own pollen ; he left also fifty-seven flowers to be
spontaneously fertilised, and this would certainly have ensued if it

«• ' Botanische Zeitung,' Jan. 1864-, Berlin, 1866, s. .372.
». 3. '^^ International Hort. Congress,

*' ' Monatslcrioht Akad. Wissen.' London, 1866.

114 GOOD FROM CROSSING. Chap. XVII.

had been possible, for the anthers not only touch the stigma, bnt
the pollen-tubes were seen by Dr. Hildebrand to penetrate it ;
nevertheless these eighty-four flowers did not produce a single
seed-capsule ! This whole case is highly instructive, as it shows
how widely different the action of the same pollen is, according as
it is i)laced on the stigma of the same flower, or on that of another
flower on the same raceme, or on that of a distinct plant.

With exotic Orchids several analogous cases have been observed,
chiefly by Mr. John Scott.*^^ Oncidium sphacelatum has effective
pollen, for Mr. Scott fertilised two distinct species with it: the
ovules are likewise capable of impregnation, for they were readily
fertilised by the pollen of 0. divaricatum ; nevertheless, between
one and two hundred flowers fertilised by their own pollen did not
produce a single capsule, though the stigmas were penetrated by
the pollen-tubes. Mr. Eobertson Munro, of the Koyal Botanic
Gardens of Edinburgh, also informs me (1864) tliat a hundred and
twenty flowers of this same species were fertilised by him with
their own pollen, and did not produce a capsule, but eight flowers,
fertilised by the pollen of 0. diuaricatum, produced four fine cap-
sules : again, between two and three hundred flowers of 0. divari-
catum, fertilised by their own pollen, did not set a capsule, but
twelve flowers fertilised by O.jitxuosum produced eight fine cap-
sules : so that here we have three utterly self-impotent species, with
their male and female organs perfect, as shown by their mutual
fertilisation. In these cases fertilisation was effected only by the
aid of a distinct species. But, as we shall presently see, distinct
plants, raised from seed, of Oncidium flexuosum, and probably of the
other species, would have been perfectly capable of fertilising each
other, for this is the natural process. Again, Mr. Scott found that the
pollen of a plant of 0. microckilum was efi'ective, for with it he ferti-
lised two distinct species ; he found its ovules good, for they could
be fertilised by the pollen of one of these species, and by the pollen
of a distinct plant of 0. microchilum ; but they could not be ferti-
lised by pollen of the same plant, though the pollen-tubes penetrated
the stigma. An analogous case has been recorded by M. Eiviere,'^"
with two plants of 0. caiK-ndishiauum, which were both self-sterile,
but reciprocally fertilised each other. All these cases refer to the
genus Oncidium, but j\Ir. Scott found that Maxillaria atro-rubens
was " totally insusceptible of fertilisation with its own pollen," but
fertilised, and was fertilised by, a widely distinct species, viz. M,
squalens.

As these orchids had been grown under unnatural conditions in
hot-houses, I concluded that their self-sterility was due to this
cause. But Fritz Mliller informs me that at Desterro, in Brazil, he

69 ;

Proc. Bot. Soc. of Edinburgh,' Liun. Soc.,' vol. viii. Bot., 1864, p.

May, 1863 : these observations are 162.

given in abstract, and others are ^" Prof. Lecoq, * De la Fecondation,

added, in the 'Journal of Proc. of 2nd edit.^ 1862, p. 76.

Chap. XVII. SELF-IMPOTENT PLANTS. 115

fertilised above one hundred flowers of the above-mentioned Onci
dium fltxuosnm, which is there endemic, with its own pollen, and
with that taken from distinct plants : all the former were sterile,
whilst those fertilised by pollen from ^mj other plant of the same
species were fertile. During the first three days there was no
difference in the action of the two kinds of pollen : that placed on
stigma of the same plant separated in the usual manner into grains,
and emitted tubes which penetrated the column, and the stigmatic
chamber shut itself; but only those flowers which had been fertilised
by pollen taken from a distmct j^lant produced seed-capsules. On
a subsequent occasion these experiments were repeated on a large
scale with the same result. Fritz Miiller found that foar other
endemic specios of Oncidium were in like manner utterly sterile
with their own pollen, but fertile with that from any other plant :
some of them likewise produced seed-capsules when impregnated
with pollen of widely distinct genera, such as Cyrtopodium, and
Bodriguczia. Oncidium crisjium, however, differs from the fore-
going species in varying much in its self-sterility ; some plants
producing tine pods with their own pollen, others failing to do so
in two or three instances, Fritz Miiller observed that the pods i)ro-
duced by pollen taken from a distinct flower on the same plant, were
larger than those produced by the flower's own pollen. In Epidm-
drum cinnabar inurn, an orchid belonging to another division of the
family, fine pods were produced by the plant's own pollen, but they
contained by weight only about half as much seed as the capsules
which had been fertilised by pollen from a distinct plant, and in
one instance from a distinct species ; moreover, a very large propor-
tion, and in some cases nearly all the seeds produced by the plant's
own pollen, were destitute of an embryo. Some self-fertilised
cajisules of a Maxillaria were in a similar state.

Another observation made by Fritz Miiller is highly remarkable,
namely, that with various orchids the plant's own pollen not only
fails to impregnate the flower, but acts on the stigma, and is acted,
on, in an injurious or poisonous manner. This is shown by the
surface of the stigma in contact with the pollen, and by the pollen
itself, becoming in from three to five days dark brown, and then
decaying. The discoloration and decay are not caused by
parasitic cryptograms, which were observed by Fritz Miiller in only
a single instance. These changes are well shown by placing on
the same stigma, at the same time, the plant's own pollen and
that from a distinct plant of the same species, or of another
species, or even of another and widely remote genus. Thus,
on the stigma of Oncidiam jiexaomm, the plant's own pollen and
that from a distinct plant were placed side by side, and in five days'
time the latter was perfectly fresh, whilst the plant S' own pollen
was brown. On the other hand, when the pollen of a distinct plant
of the Oncidium fiexaosum, and of the Epidttidrtim zebra (nov.
spec, f) were placed together on the same stigma, they behaved in
exactly the same manner, the grains separating, emitting tubes.

116 GOOD FROM CROSSING. Chap. XVII.

and penetrating the stigma, so that the two pollen-masses, after an
interval of eleven days, could not be distinguished except by the
difference of their candicles, which, of course, undergo no change.
Fritz Mliller has, moreover, made a large number of crosses between
orchids belonging to distinct sjDecies and genera, and he finds that
in all cases when the flowers are not fertilised their footstalks first
begin to wither ; and the withering slowly spreads upwards until
the germens fall off, after an interval of one or two weeks, and in
one instance of between six and seven weeks ; but even in this latter
case, and in most other cases, the pollen and stigma remained in
appearance fresh. Occasionally, however, the pollen becomes
brownish, generally on the external surface, and not in contact with
the stigma, as is invariably the case when the plant's own j)ollen is
aj^plied.

Fritz Miiller observed the poisonous action of the plant's own
pollen in the above-mentioned Oncidium fiexuosum, 0. u7ncorne,
'piihcH (J), and in two other unnamed species. Also in two species of
Kodriguezia, in two of Notylia, in one of Burlingtonia, and of a
fourth genus in the same group. In all these cases, except the last,
it was i^roved that the flowers were, as might have been expected,
lertile with jDollen from a distinct plant of the same species.
Numerous flowers of one species of Notylia were fertilised with
pollen from the same raceme ; in two days' time they all withered,
the germens began to shrink, the pollen-masses became dark brown,
and not one pollen-gi'ain emitted a tube. So that in this orchid the
injurious action of the plant's own pollen is more rapid than with
Oncidium flexuosum. Eight other flowers on the same raceme were
fertilised with pollen from a distinct plant of the same species : two
of these were dissected, and their stigmas were found to be pene-
trated by numberless pollen-tubes ; and the germens of the other
six flow^ers became well developed. On a subsequent occasion many
other flowers were fertilised with their own pollen, and all fell olf
dead in a few days ; w^hilst some flowers on the same raceme which
had been left simply unfertilised adhered and long remained fresh.
We have seen that in cross-unions between extremely distinct
orchids the pollen long remains undecayed ; but Notylia behaved
in this respect differently ; for when its pollen was placed on the
stigma of Oncidium Jiexuosum, both tlie stigma and pollen quickly
became dark brown, in the same manner as if the plant's own pollen
had been applied.

Fritz Miiller suggests that, as in all these cases the plant's own
pollen is not only impotent (thus eftectually preventing self-fertilisa-
tion), but likewise prevents, as was ascertained in the case of the
Notylia and Oncidium flexzwsum, the action of subsequently applied
pollen from a distinct individual, it would be an advantage to the
plant to have its own pollen rendered more and more deleterious ;
for the germens would thus quickly be killed, and dropping off,
there would be no further waste in nourishing a part which
ultimately could be of no avail

Chap. XVII. SELF-IMPOTENT PLANTS. 117

The same uatiiralist found in Brazil three plants of a Bignonia
growing near together. He fertilised twenty-nine flowerets on one
of them with their own pollen, and they did not set a single
capsule. Thirty flowers were then fertilised with pollen from a
distnict plant, one of the three, and they yielded only two capsules.
Lastly, five flowers were fertilised with jDollen from a fourth
plant growing at a distance, and all five produced capsules.
Fritz Miiller thinks that the three plants which grew near one
another were probably seedlings from the same parent, and that
from being closely related, they acted very feebly on one another.
This view is extremely probable, for he has since shown in a
remarkable paper,''^ that in the case of some Brazilian species of
Abutilon, which are self-sterile, and between which he raised some
comxDlex hybrids, that these, if near relatives, were much less fertile
inter se, than when not closely related.

We now come to cases closely analogous with those just
given, but different in so far that only certain individuals
of the species are self-sterile. This self-impotence does not
depend on the pollen or ovules being in an unfit slate for
fertilisation, for both have been found effective in union with
other plants of the same or of a distinct species. The fact
of plants having acquired so peculiar a constitution, that they
can be fertilised more readil}" by the pollen of a distinct
species than by their own, is exactly the reverse of what
occurs with all ordinary species. For in the latter the two
sexual elements of the same individual plant are of course
capable of freely acting on each other ; but are so constituted
that they are more or less impotent when brought into union
with the sexual elements of a distinct species, and produce
more or less sterile hybrids.

Gartner experimented on two plants of Lobeh'a fulgens, brought
from separate places, and found ^- that their pollen was good, for he
fertihsed with it L. cardinalis and syphilitica ; their ovules were
likewise good, for they were fertilised by the pollen of these same
two species ; but these two plants oiL.fulgens could not be fertilised
by their own pollen, as can generally be effected with perfect ease
with this species. Again, the pollen of a plant of Verhascum nigrum
grown in a pot was found by Gartner '^ capable of fertilising V.
hjchnitis and V. austriacum ; the ovules could be fertilised by the

" ' Jenaische Zeitschrift fiir Natur- Naturalist,' 1874, p. 223.
wiss.* B. vii. p. 22, 1872, and p. 441, "- ' Bastarderzeugung,* s. 64, 357.

1873. A large part of this paper has ^^ Ibid., s. 357.

been translated in the ' American

118

GOOD FEOM CROSSING.

Chap. XVII.

pollen of V. thapsus ; but the flowers could not be fertilised by their
own pollen. Kolreuter, also,^* gives the case of three garden plants
of Verbascum phoeniceum, which bore during two years many flowers ;
the?e he fertilised successfully with the pollen of no less than
four distinct species, but they produced not a seed with their own
apparently good pollen ; subsequently these same plants, and others
raised from seed, assumed a strangely fluctuating condition, being
temporarily sterile on the male or female side, or on both sides, and
sometimes fertile on both sides; but two of the plants were perfectly
fertile throughout the summer.

With Reseda odorata I have found certain individuals quite sterile
with their own pollen, and so it is with the indigenous lieseda lutea.
The self-sterile plants of both species were perfectly fertile when
crossed with pollen from any other individual of the same species.
These observations will hereafter be published in another work, in
which I shall also show that seeds sent to me by Fritz Miiller
produced by plants of Eschscholtzia californica which were quite
self-sterile in Brazil, yielded in this country j^lants which were only
slightly self-sterile.

It appears''^ that certain flowers on certain plants of LiHum.
candidum can be fertilised more freely by pollen from a distinct
individual than by their own. So, again, with the varieties of the
potato. Tinzmann,'*^ who made many trials with this f)lant, says
that pollen from another variety sometimes "exerts a powerful
" influence, and I have found sorts of potatoes which would not
" bear seed from impregnation with the pollen of their own flowers
" would bear it when impregnated with other pollen," It does
not, however, appear to have been proved that the pollen which
failed to act on the flow^er's own stigma w^as in itself good.

In the genus Passiflora it has long been known that several
species do not produce fruit, unless fertilised by pollen taken from
distinct species: thus, Mr. Mowbray ^"^ found that he could not get
fruit from P. alata and racemosa except by reciprocally fertilising
them with each other's pollen ; and similar facts have been observed
in Germany and France.'^^ I have received two accounts of P.
quadrangular is never producing fruit from its own pollen, but
doing so freely when fertilised in one case with the pollen of P.
coerulea, and in another case with that of P. edidis. But in three

'♦ 'Zweite Fortsetzung,' s. 10;
* Dritte Forts.,' s. 40. Mr. Scott like-
wise fertilised fifty-four flowers of
Verbascum phocniceum, including two
varieties, with their own pollen, and
not a single capsule was produced.
Many of the pollen - grains emitted
their tubes, but only a few of them
oenetrated the stigmas ; some slight
eflect however was produced, as many
of the ovaries became somewhat

developed : ' Journal Asiatic Soc. Ben-
gal,' 1867, p. 150.

" Duvernoy, quoted by Gartner,
* Bastarderzeugung,' s. 334.

'^ ' Gardener's Chronicle,' 1846, p.
183.

^^ ' Transact. Hort. Soc.,' vol, vii.,
1830, p. 95.

•^ Prof. Lecoq, ' De la Fecondation,*
1845, p. 70; Gartner, ' Bastarder-
zeuf^ung,* s. 64.

Chap. XVII. SELF-IMFOTENT PLANTS. 119

other cases this species fruited freely when fertilised with its own
pollen ; and the writer in one case attributed the favourable result
to the temperature of the house having been raised from 5° to lO'^
Fahr. above the former temperature, after the flowers were fertilised.'^
"With respect to P. Janrifolia, a cultivator of much experience has
recently remarked ^*^ that the flowers "must be fertilised with the
pollen of P. coendea, or of some other common kind, as their own
pollen will not fertilise them." But the fullest details on this
subject have been given by Messrs. Scott and Eobertson Munro :^^
plants of fassljiora racemosa, coerulea, and alata flowered profusely
during many years in the Botanic Gardens of Edinburgh, and,
though repeatedly fertilised with their own pollen, never produced
any seed ; yet this occurred at once with all three species when they
were crossed together in various ways. In the case of P. coerulea
three plants, two of which grew in the Botanic Gardens, were all
rendered fertile, merely by impregnating each with pollen of one of
the others. The same result was attained in the same manner with
P. alata, but with only one plant out of three. As so many self-
sterile species of Passiflora have been mentioned, it should be
stated that the flowers of the annual P. gracilis are nearly as fertile
with their own pollen as with that from a distinct plant; thus
sixteen flowers spontaneously self-fertilised produced fruit, each
containing on an average 21"3 seed, whilst fruit from fourteen
crossed flowers contained 24:'l seed.

Eeturning to P. alata, I have received (1866) some interesting
details from Mr. Eobertson Munro. Three plants, including one in
England, have already been mentioned which were inveterately
self-sterile, and Mr. Munro informs me of several others which,
after repeated trials during many years, have been found in the
same predicament. At some other places, however, this species
fruits readily when fertilised with its own pollen. At Taymouth
Castle there is a plant which was formerly grafted by Mr. Donaldson
on a distinct species, name unknown, and ever since the operation
it has produced fruit in abundance by its own pollen ; so that this
small and unnatural change in the state of this plant has restored
its self- fertility ! Some of the seedlings from the Taymouth Castle
plant were found to be not only sterile with their own pollen, but
with each other's pollen, and with the pollen of distinct species.
Pollen from the Taymouth plant failed to fertilise certain plants of the
same species, but was successful on one plant in the Edinburgh
Botanic Gardens. Seedlmgs were raised from this latter union, and
some of their flowers were fertilised by Mr. Munro with their own
pollen ; but they were found to be as self-impotent as the mother-
plant had always proved, except when fertilised by the grafted

'9 'Gard. Chron.,' 1868, p. 1341. vol. viii., 18G4, p. 11G8. Mr. Robert-

®" ' Gardener's Chron.,' 1866, p. son Munro, in ' Trans. Bot. Soc' of

1068. Edinburgh, vol. ix. p. 399.
*^ ' Journal of Proc. of Linn. Soc.,*

120 GOOD FROM CROSSING. Chap. XVIL

Taymouth plant, and except, as we shall see, when fertilised by her
own seedlings. For Mr. Munro fertilised eighteen flowers on the self-
impotent mother-plant with pollen from these her own self-impotent
seedlings, and obtained, remarkable as the fact is, eighteen fine
capsnles full of excellent seed ! I have met with no case in regard
to plants which shows so well as this of F. alata, on what small and
mysterious causes complete fertility or complete sterility depends.

The facts hitherto given relate to the mnch-lessened or
completely destroyed fertility of pure species when impreg-
nated with their own pollen, in comparison with their
fertility when impregnated by distinct individuals or distinct
species ; but closely analogous facts have been observed with
hybrids.

Herbert states ^^ that having in flower at the same time nine
hybrid Hippeastrums, of complicated origin, descended from
several species, he found that " almost every flower touched with
" pollen from another cross produced seed abundantly, and those
" which were touched with their own pollen either failed entirely,
" or formed slowly a pod of interior size, with fewer seeds." In
the * Horticultural Journal ' he adds that " the admission of the
*' pollen of another cross-bred Hippeastrum (however complicated
" the cross) to any one flower of the number, is almost sure to
" check the fructification of the others." In a letter written to me
in 1839, Dr. Herbert says that he bad already tried these experi-
ments during five consecutive years, and he subsequently repeated
them, with the same invariable result. He was thus led to make an
analogous trial on a pure species, namely, on the Bippeastrvm auUcnm,
which he had lately imported from Brazil: this bulb produced
four flowers, three of which were fertilised by their own pollen, and
the fourth by the pollen of a triple cross between //. hulhaJosum,
reginos, a^ndviUatum ; the result was, that " the ovaries of the three
" first flowers soon ceased to grow, and after a few days perished
" entirely : whereas the jDod impregnated by the hybrid made
" vigorous and rapid progress to maturity, and bore good seed,
" which vegetated freely." This is, indeed, as Herbert remarks,
" a strange truth," but not so strange as it then appeared.

As a confirmation of these statements, I may add that Mr. M.
Mayes,^^ after much experience in crossing the species of Amaryllis
(Hippeastrum), says, " neither the species nor the hybrids will, we
" are well aware, produce seed so abundantly from their own
" pollen as from that of others." So, again, Mr. Bidwell, in New

®2 ' Amaryllidacese,* 1837, p. 371 ; ®^ Loudon's 'Gardener's Magazine,

'Journal of Hort. Soc.,' vol. ii., 1847, vol. xi., 1835, p. 2(>0.
p. 19.

Chap. XYII. SELF-IMPOTENT PLANTS. 121

South Wales/'' asserts that Amaryllis helladonna bears many more
seeds when fertilised by the pollen of Brunsivigia {Amaryllis of some
authors) jos'phince or of B. muUijlora, than when fertilised by its
own pollen. Mr. Beaton dusted four flowers of a Cyrtanthus with
their own pollen, and four with the pollen of Vnllota (Amaryllis)
purpurea; on the seventh day "those which received their own
" pollen slackened their growth, and ultimately perished ; those
" which were crossed with the Yallota held on."**^ "These latter cases,
however, relate to uncrossed species, like those before given with
respect to Passiflora, Orchids, &c., and are here referred to only
because the plants belong to the same group of Amaryllidacese.

In the experiments on the hybrid Hippeastrums, if Herbert had
found that the pollen of two or three kinds alone had been more
eflficient on certain kinds than their own pollen, it might have been
argued that these, from their mixed parentage, had a closer mutual
affinity than the others ; but this explanation is inadmissible, for
the^ trials were made reciprocally backwards and forwards on nine
different hybrids ; and a cross, whichever way taken, always proved
highly beneficial. I can add a striking and analogous case from
experiments made by the Eev. A. Eawson, of Bromley Common,
with some complex hybrids of Gladiolus. This skilful horticul-
turist possessed a number of French varieties, differing from each
other only in the colour and size of the flowers, all descended from
Gandavensis, a well-known old hybrid, said to be descended from
G. nafalensis by the pollen of G. o2->2-)ositiflorns.^^ Mr. Eawson, after
repeated trials, found that none of the varieties would set seed with
their own pollen, although taken from distinct plants of the same
variety (which had, of course, been propagated by bulbs), but that
they all seeded freely with pollen from any other variety. To give
two examples : Ophir did not produce a capsule with its own pollen,
but when fertilised with that of Janire, Brenchleyensis, Yulcain
and Linne, it produced ten fine capsules ; but the pollen of Ophir
was good, for when Linne was fertilised by it seven capsules were
produced. This latter variety, on the other hand, was utterly
barren with its own pollen, which we have seen was perfectly
efficient on Ophir. Altogether, Mr. Eawson, in the year 1861,
fertihsed twenty-six flowers borne by four varieties with pollen
taken from other varieties, and every single flower produced a fine
seed-capsule ; whereas fifty-two flowers on the same plants, fertilised
at the same time with their own pollen, did not yield a single seed-
capsule. Mr. Eawson fertilised, in some cases, the alternate flowers,

*^ ' Gardener*s Chronicle,' 1850, p. Hort.,' 18G1, p. 453. Lecoq, ho^t-ever

470. (' De la Fecond.,' 1862, p. 369), states

*^ ' Journal Hort. Soc.,* vol. v. p. that this hybrid is descended from

135. The seedlings thus raised were G. psittacinus&XiA cardinalis ; but this

given to the Hort. Soc. ; but I rind, on is opposed to Herbert's experience,

inquiry, that they unfortunately died who found that the former speciei

the following winter. could not be crossed.

*^ Mr. D. Beaton, in ' Journal of

122 GOOD FROM CROSSING. Chap. XYIL

and in other cases all those clown one side of the spike, with pollen
of other varieties, and the reruaining flowers with their own pollen.
I saw these plants when the capsules were nearly mature, and
their curious arrangement at once brought full conviction to the
mind that an immense advantage had been derived from crossing
these hybrids.

Lastly, I have heard from Dr. E. Bornet, of Antibes, who has
made numerous experiments in crossing the species of Cistus, but
has not yet published the results, that, when any of these hybrids
are fertile, they may be said to be, in regard to function, dioecious ;
" for the flowers are always sterile when the pistil is fertilised by
" pollen taken from the same flower or from flowers on the same
" plant. But they are often fertile if pollen be employed from a
" distinct individual of the same hybrid nature, or from a h^'brid
" made by a reciprocal cross."

Conclusion. — That plants should be self-sterile, although
both sexual elements are in a fi^t state for reproduction, appears
at first sight opposed to all analogy. With respect to the
species, all the individuals of which are in this state, although
living under their natural conditions, we may conclude that
their self-sterility has been acquired for the sake of effectually
preventing self-fertilisation. The case is closely analogous
with that of dimorphic and trimorphic or heterostj'led jDlants,
which can be fully fertilised only by plants belonging to a
different form, and not, as in the foregoing cases, indifferently
by any other individual of the species. Some of these hetero-
styled plants are completely sterile -with pollen taken from
the same plant or from the same form. With respect to
species living under their natural conditions, of which only
certain individuals are self-sterile (as with Reseda lutea), it
is TDrobable that these have been rendered self-sterile to ensure
occasional cross-fertilisation, whilst other individuals have
remained self-fertile to ensure the propagation of the species.
The case seems to be paiallel with that of plants which
produce, as Hermann Miiller has discovered, two forms
— one bearing more conspicuous flowers with their structure
adapted for cross-fertilisation by insects, and the other form
with less conspicuous flowers adapted for self-fertilisation.
The self-sterility, however, of some of the foregoing plants
is incidental on the conditions to which they have been
subjected, as with the Eschscholtzia, the Verhascum pJioe-

Chap. XVII. CONCLUSION. 123

fiiceum (the sterility of which varied according to the season),
and with the Passiflora alata, which recovered its self-fertility
when grafted on a different stock.

It is interesting to observe in the above several cases the
graduated series from plants which, when fertilised by their
own pollen, yield the full number of seeds, but with the
seedlings a little dwarfed in stature — to plants which when
self-fertilised yield few seeds — to those which yield none,
but have their ovaria somewhat developed — and, lastly, to
those in which the plant's own pollen and stigma mutually
act on one another like poison. It is also interesting to
observe on how slight a difference in the nature of the pollen
or of the ovules complete self-sterility or complete self-fertility
must depend in some of the above cases. Every individual
of the self-sterile species appears to be capable of producing
the full complement of seed when fertilised by the pollen of
any other individual (though judging from the facts givea
with respect to Abutilon the nearest kin must be excepted) ;
but not one individual can be fertilised by its own pollen.
As every organism differs in some slight degree from every
other individual of the same species, so no doubt it is with
their pollen and ovules ; and in the above cases we must
believe that complete self-sterility and complete self-fertility
depend on such slight differences in the ovules and pollen, and
not their having been differentiated in some special manner
in relation to one another ; for it is impossible that the sexual
elements of many thousand individuals should have been
specialised in relation to every other individual. In some, how-
ever, of the above cases, as with certain Passifloras, an amount
of differentiation between the pollen and ovules sufficient
for fertilisation is gained only by employing pollen from a
distinct species ; but this is probably the result of such plants
having been rendered somewhat sterile from the unnatural
conditions to which they have been exposed.

Exotic animals confined in menageries are sometimes in
nearly the same state as the above-described self-impotent
plants ; for, as we shall see in the following chapter, certain
monkeys, the larger carnivora, several finches, geese, and
pheasants, cross together, quite as freely as, or even more

124 GOOD FROM CROSSINa. Chap. XVIL

freely tlian the individuals of tlie same species breed together.
Cases will, also, be given of sexual incompatibility between
certain male and female domesticated animals, which, never-
theless, are fertile when matched with any other individual
of the same kind.

In the early part of this chapter it was sho\\Ti that the
crossing of individuals belonging to distinct families of the
same race, or to different races or species, gives increased size
and constitutional vigour to the offspring, and, except in the
case of crossed species, increased fertility. The evidence
rests on the universal testimony of breeders (for it should be
observed that I am not here speaking of the evil results of
close interbreeding), and is practically exemplified in the
higher value of cross-bred animals for immediate consump-
tion. The good results of crossing have also been demon-
strated with some animals and with numerous plants, by
actual weight and measurement. Although animals of pure
blood will obviously be deteriorated by crossing, as far as
their characteristic qualities are concerned, there seems to be
no exception to the rule that advantages of the kind just
mentioned are thus gained, even when there has not been any
previous close interbreeding ; and the rule applies to such
animals as cattle and sheep, which can long resist breeding
in-and-in between the nearest blood-relations.

In the case of crossed species, although size, vigour, j^re-
cocity, and hardiness are, with rare exceptions, gained, fer-
tility, in a greater or less degree, is lost ; but the gain in the
above respects can hardly be attributed to the principle of
compensation ; for there is no close parallelism between the-
increased size and vigour of hybrid offspring and their
sterility. Moreover, it has been clearly proved that mongrels
which are perfectly fertile gain these same advantages as well
as sterile hybrids.

With the higher animals no special adaptations for ensuring
occasional crosses between distinct families seem to exist.
The eagerness of the males, leading to severe competition
between them, is sufficient ; for even with gregarious animals,
the old and dominant males will be dispossessed after a time
and it would be a mere chance if a closely related member

Chap. XVII. CONCLUSION. 125

of the same family were to be the victorious successor. The
structure of many of the lower animals, when they are
hermaphrodites, is such as to prevent the ovules being fer-
tilised by the male element of the same individual ; so that
the concourse of two individuals is necessary. In other cases
the access of the male element of a distinct individual is
at least possible. With plants, which are affixed to the
ground and cannot wander from place to place like animals,
the numerous adaptations for cross-fertilisation are wonder-
fully perfect, as has been admitted by ever}^ one who has
studied the subject.

The evil consequences of long-continued close interbreeding
are not so easily recognised as the good effects from crossing,
for the deterioration is gradual. Nevertheless, it is the
general opinion of those who have had most experience,
especially with animals which propagate quickly, that evil
does inevitably follow sooner or later, but at different rates
with different animals. No doubt a false belief may, like a
superstition, prevail widely ; 3'et it is difficult to suppose that
so many acute observers have all been deceived at the expense
of much cost and trouble. A male animal may sometimes be
paired with his daughter, granddaughter, and so on, even for
seven generations, without any manifest bad result : but the
experiment has never been tried of matching brothers and
sisters, which is considered the closest form of interbreeding,
for an equal number of generations. There is good reason to
believe that by keeping the members of the same family in
distinct bodies, especially if exposed to somewhat different
conditions of life, and by occasionally crossing these families,
the evil results of interbreeding may be much diminished or
quite eliminated. These results are loss of constitutional
vigour, size, and fertility; but there is no necessary dete-
rioration in the general form of the body, or in other good
qualities. We have seen that with pigs first-rate animals
have been produced after long-continued close interbreeding,
though they had become extremely infertile when paired
with their near relations. The loss of fertility, when it
occurs, f-eems never to be absolute, but only relative to
animals of the same blood ; so that this sterility is to a certain

126 GOOD FROM CROSSING. Chap. XYII.

extent analof^ous witL. that of self- impotent plants whicli
cannot be fertilised by tlieir own pollen, but are perfectly
fertile with, pollen of any other individual of the same species.
The fact of infertility of this peculiar nature being one of the
results of long-continued interbreeding, shows that inter-
breeding does not act merely by combining and augmenting
various morbid tendencies common to both parents ; for
animals with such tendencies, if not at the time actually ill,
can generally propagate their kind. Although offspring
descended from the nearest blood-relations are not necessarily
deteriorated in structure, yet some authors believe that they
are eminently liable to malformations ; and this is not im-
probable, as everything which lessens the vital powers acts
in this manner. Instances of this kind have been recorded
in the case of pigs, bloodhounds, and some other animals.

Finally, when we consider the various facts now given
which plainly show that good follows from crossing, and less
plainly that evil follows from close interbreeding, and when
we bear in mind that with very many organisms elaborate
provisions have been made for the occasional union of distinct
individuals, the existence of a great law of nature is almost
proved ; namely, that the crossing of animals and plants
which are not closely related to each other is highly beneficial
or even necessary, and that interbreeding prolonged during
many generations is injurious.

Ca4P. XVIII. GOOD FROM CHANGED CONDITIONS. 127

CHAPTER XYIII.

ON THE ADVANTAGES AND DISADVANTAGES OF CHANGED
CONDITIONS OF LIFE : STERILITY FROM VARIOUS CAUSES.

ON THE GOOD DERIVED FROM SLIGHT CHANGES IN THE CONDITIONS OF LIFE
— STERILITY FROM CHANGED CONDITIONS, IN ANIMALS, IN THEIR NATIVE
COUNTRY AND IN MENAGERIES — MAMMALS, BIRDS, AND INSECTS — LOSS OP
SECONDARY SEXUAL CHARACTERS AND OF INSTINCTS — CAUSES OF STERILITY

STERILITY OF DOMESTICATED ANIMALS FROM CHANGED CONDITIONS —

SEXUAL INCOMPATIBILITY OF INDIVIDUAL ANIMALS — STERILITY OF PLANTS
FROM CHANGED CONDITIONS OF LIFE — CONTABESCENCE OF THE ANTHEl.'S
— MONSTROSITIES AS A CAUSE OP STERILITY — DOUBLE FLOWERS — SEEDLESS
FRUIT — STERILITY FROM THE EXCESSIVE DEVELOPMENT OF THE ORGANS
OP VEGETATION — FROM LONG-CONTINUED PROPAGATION BY BUDS — IN-
CIPIENT STERILITY THE PRIMARY CAUSE OP DOUBLE FLOWERS AND
SEEDLESS FRUIT.

On tlie Good derived from slight Changes in the Conditions of
Life. —In considering whether any facts were known which
might throw light on the conclusion arrived at in the last
chapter, namely, that benefits ensue from crossing, and that
it is a law of nature that all organic beings should occasionally
cross, it appeared to me probable that the good derived from
slight changes in the conditions of life, from being an analo
gous phenomenon, might serve this purpose. Ko two indi-
viduals, and still less no two varieties, are absolutely alike
in constitution and structure ; and when the germ of one is
fertilised by the male element of another, we may believe that
it is acted on in a somewhat similar manner as an individual
when exposed to slightly changed conditions. Now, every
one must have observed the remarkable influence on conva-
lescents of a change of residence, and no medical man doubts
the truth of this fact. Small farmers who hold but little
land are convinced that their cattle derive great benefit from
a change of pasture. In the case of plants, the evidence is
strong that a great advantage is derived from exchanging
seeds, tubers, bulbs, and cuttings from one soil or place to
another as different as possible.

128

ON THE GOOD DERIVED

Chap. XVIII.

The belief that plants are thus benefited, whether or not well
founded, has been firmly maintained from the time of Columella,
who wrote shortly after the Christian era, to the present day ; and
it now prevails in England, France, and Germany,^ A sagacious
observer, Bradley, writing in 1724,^ says, " When we once become
" Masters of a good Sort of Seed, we should at least put it into
" Two or Three Hands, where the Soils and Situations are as dif-
" ferent as possible ; and every Year the Parties should change
" with one another ; by which Means, I find the Goodness of the
" Seed will be maintained for several Years. For Want of this
" Use many Farmers have failed in their Crops and been great
" Losers." He then gives his own practical experience on this
bead. A modern writer ^ asserts, " Nothing can be more clearly
" established in agriculture than that the continual growth of any
" one variety in the same district makes it liable to deterioration
" either in quality or quantity." Another writer states that he
sowed close together in the same field two lots of wheat-seed, the
product of the same original stock, one of which had been grown
on the same laud and the other at a distance, and the difference in
favour of the crop from the latter seed was remarkable. A gentle-
man in Surrey who has long made it his business to raise wheat to
sell for seed, and who has constantly realised in the market higher
prices than others, assures me that he finds it indispensable con-
tinually to change his seed ; and that for this purpose he keeps two
farms differing much in soil and elevation.

With respect to the tubers of the jDotato, I find that at the present
day the practice of exchanging sets is almost everywhere followed.
The great growers of potatoes in Lancashire formerly used to get
tubers from Scotland, but they found that " a change from the
moss-lands, and vice versa, was generally sufficient." In former
times in France the crop of potatoes in the Yosges had become
reduced in the course of fifty or sixty years in the proportion from
120-150 to 80-40 bushels ; and the famous Oberlin attributed the
surprising good which he effected in large part to changing the sets.^

A ^^•ell-known practical gardener, Mr. Eobson,^ positively states

* For England, see below. For
Germany, s^o'Metzger, ' Getreidearten,'
1841, s. 63. For France, Loiseleur-
Deslongchamps (' Consid. sur les
Coreales,' 1843, p. 200) gives nu-
merous references on this stibject. For
Southern France, see Godron, ' Florula
Juvenalis,' 1854, p. 28.

2 'A General Treatise of Hus-
bandry,' vol. iii. p. 58.

* 'Gardener's Chronicle and Agri-
cult. Gazette,' 1858, p. 247 ; and for
the second statement, Ibid., 1850, p.
702. On this same subject, see also

Kev. D. Walker's ' Prize Essay of
Highland Agri'^ult. Soc.,' vol. ii. p.
200. Also Marshall's 'Minutes of
Agriculture,' Nr^vembcr, 1775.

* Oberlin's ' Memoirs,' Eng. trans-
lat., p. 73. For J ancashire, see
Marshall's ' Review of Reports,' 1808,
p. 295.

5 'Cottage Gardener,' 1856, p. 186.
For Mr. Kobson's subsequent state-
ments, see ' Journal of Horticulture,
Feb. 18, 1866, p. 121. For Mr
Abbey's remarks on grafting, &c..
Ibid., July 18, 1865, p. 44.

Chap. XVIII. FIIOM CHANGED COXDITIOXS. 129

that he has himself witnessed, decided advantage from obtaining
bulbs of the onion, tubers of the potato, and Ycirious seeds, all of
the same kind, from different soils and distant parts of England.
He further states that with plants propagated by cuttings, as with
the Pelargonium, and especially the Dahlia, manifest advantage is
derived from getting plants of the same variety, which have been
cultivated in another j^lace ; or, "where the extent of the place
" allows, to take cuttings from one description of soil to plant on
" another, so as to afford the change that seems so necessary to the
" well-being of the plants." He maintains that after a time an
exchange of this nature is " forced on the grower, whether he be
" prepared for it or not." Similar remarks have been made by
another excellent gardener, Mr. Fish, namely, that cuttings of the
same variety of Calceolaria, which he obtained from a neighbour,
" showed much greater vigour than some of his own that were
" treated in exactly the same manner," and he attributed this
solely to his own plants having become " to a certain extent worn
" out or tired of their quarters." Something of this kind appar-
ently occurs in grafting and budding fruit-trees ; for, according to
Mr. Abbey, grafts or buds generally take with greater facility on
a distinct variety or even species, or on a stock previously grafted,
than on stocks raised from seeds of the variety which is to be
grafted ; and he believes this cannot be altogether explained by
the stocks in question being better adapted to the soil and climate
of the place. It should, however, be added, that varieties grafted
or budded on very distinct kinds, though they may take more
readily and grow at first more vigorously than when grafted on
closely allied stocks, afterwards often become unhealthy.

I have studied M. Tessier's careful and elaborate experiments,^
made to disprove the common belief that good is derived from a
change of seed ; and he certainly shows that the same seed may
with care be cultivated on the same farm (it is not stated whether
on exactly the same soil) for ten consecutive years without loss.
Another excellent observer, Colonel Le Couteur,' has come to the
same conclusion ; but then he expressly adds, if the same seed be
used, " that which is grown on land manured from the mixen one
" year becomes seed for land prepared with lime, and that again
" becomes seed for land dressed with ashes, then for land dressed
" with mixed manure, and so on." But this in effect is a systematic
exchange of seed, within the limits of the same farm.

On the whole the belief, which has long been held by many
cultivators, that good follows from exchanging seed, tubers,
&c., seems to be fairly well founded. It seems hardl}'' credible
that the advantage thus derived can be due to the seeds,
especially if very smtill ones, obtaining in one soil some

^ ' Mem. de I'Acad. des Sciences,' ^ ' On the Varieties of Wheat,' p*

1790. p. 209. 52.

130 STERILITY FROM Chap. XVIII.

chemical element deficient in the other and in sufficient
quantity to influence the whole after-growth of the plant.
As plants after once germinating are fixed to the same spot,
it might have heen anticipated that they would show the
good efiects of a change more plainly than do animals which
continually w^ander about ; and this aj^parently is the case.
Life depending on, or consisting in, an incessant play of the
most complex forces, it would appear that their action is
in some way stimulated by slight changes in the circum-
stances to which each organism is exposed. All forces through-
out nature, as Mr. Herbert Spencer ^ remarks, tend towards
an equilibrium, and for the life of each organism it is neces-
sary that this tendency should be checked. These views and
the foregoing facts probably throw light, on the one hand,
on the good efiects of crossing the breed, for the germ will
be thus slightly modified or acted on by new forces ; and
on the other hand, on the evil efiects of close interbreeding
prolonged during many generations, during which the germ
will be acted on by a male having almost identically the
same constitution.

Sterility from Changed Conditions of Life.

I will now attempt to show that animals and plants, when
removed from their natural conditions, are often rendered in
some degree infertile or completely barren ; and this occurs
even when the conditions have not been greatly changed.
This conclusion is not necessarily opposed to that at which
we have just arrived, namely, that lesser changes of other
kinds are advantageous to organic beings. Our present
subject is of some importance, from having an intimate con-
nection with the causes of variability. Indirectly it perhaps
bears on the sterility of species when crossed : for as, on the
one hand, slight changes in the conditions of life are favour-
able to plants and animals, and the crossing of varieties adds

^ Mr. Spencer has fully and ably from cross-breeding, and of the evil

discussed this whole subject in his effects from great changes in the con-

' Principles of Biology,' 1864-, vol. ii. ditions and from crossing widely dis-

ch. X. In the first edition of my tinct forms, as a series of facts " con-

* Origin of Species,' 1859, p. 267, I nected together by some common but

spoke of the good effects from slight unknown bond, which is essentially

changes in the conditions of life and related to the principle of life.

Chap. XVin. CHANGED CONDITIONS. 131

to the size, vigour, and fertility of their ofi'spring ; so, on tho
other hand, certain other changes in the conditions of life
cause sterility ; and as this likewise ensues from crossing
inuch-modified forms (;r species, we have a parallel and double
series of facts, which apparently stand in close relation to
each other.

It is notorious that many animals, though perfectly tamed,
refuse to breed in captivity. Isidore Geoffrey St.-Hilaire^
consequently has drawn a broad distinction between tamed
animals which will not breed under captivity, and truly
domesticated animals which breed freely — generally more
freely, as shown in the sixteenth chapter, than in a state of
nature. It is possible and generally easy to tame most
animals ; but experience has shown that it is difficult to get
them to breed regularly, or even at all. I shall discuss this
subject in detail ; but will give only those cases which seem
most illustrative. My materials are derived from notices
scattered through various works, and especially from a Report,
kindly drawn up for me by the officers of the Zoological
Society of London, which has especial value, as it records
all the cases, during nine years from 1838-46, in which the
animals were seen to couple but produced no offspring, as well
as the cases in which they never, as far as known, coupled.
This MS. Report I have corrected by the annual Rej^orts
subsequently published up to the year 1865.^^ Many facts
are given on the breeding of the animals in that magnificent
work, ' Gleanings from the Menageries of Knowsley Hall,' by
Dr. Gray. I made, also, particular inquiries from the expe-
rienced keeper of the birds in the old Surrey Zoological
Gardens. I should premise that a slight change in the treat-
ment of animals sometimes makes a great difference in their
fertility ; and it is probable that the results observed in

* ' Essais de Zoologie Generale,' kept, and of these 1 species in 1*9

1841, p. 256. have bred at least once during the

^" Since the appearance of the first 20 years ; of 28 Marsupialia, 1 in 2*5

edition of this work, Mr. Sclater has have bred ; of 74 Carnivora, 1 in 3*0

published (' Proc. Zoolog. Soc.,' 1808, have bred; of 52 Rodentia, 1 in 4*7

p. 623) a list of the species of mam- have bred; and of Quadrumana 75

mals which have bred in the gardens species have been kept, and 1 in 6*2

from 1848 to 1867 inclusive. Of the have bred.
Artiodactyla 85 species have been

132 STERILITY FROM Chap. XVI II.

diiFerent menageries would differ. Indeed, some animals in
our Zoological Gardens liave become more productive since
tlie year 1846. It is, also, manifest from F. Cuvier's account
of the Jar din des Plant es,^^ that the animals formerly bred
much less freely there than with us ; for instance, in the
Duck tribe, which is highly prolific, only one species had at
that period produced young.

The most remarkable cases, however, are afforded by animals
kept in their native country, which, though perfectly tamed, cfuite
healtliy, and allowed some freedom, are absolutely incapable of
breeding. Eengger,^^' who in Paraguay particularly attended to
this subject, specifies six quadrupeds in this condition; and he
mentions two or three others which most rarely breed. Mr. Bates,
in his admirable w^ork on the Amazons, strongly insists on similar
cases ; ^^ and he remarks, that the fact of thoroughly tamed native
mammals and birds not breeding when kept by the Indians, cannot
be wholly accounted for by their negligence or indifference, for
the turkey and fowl are kept and bred % various remote tribes.
In almost every part of the world — for instance, in the interior of
Africa, and in several of the Polynesian islands — the natives are
extremely fond of taming the indigenous quadrupeds and birds;
but they rarely or never succeed in getting them to breed.

The most notorious case of an animal not breeding in captivity
is that of the elephant. Elephants are kept in large numbers in
their native Indian home, live to old age, and are vigorous enough
for the severest labour ; yet, with a very few exceptions, they have
never been known even to couple, though both males and females
have their proper periodical seasons. If, however, we proceed a
little eastward to Ava, we hear from Mr. Crawfurd ^"^ that their
" breeding in the domestic state, or at least in the half-domestic
state in which the female elephants are generally kept, is of every-
day occurrence ;" and Mr. Crawfurd informs me that he believes
that the difference must be attributed solely to the females being
allowed to roam the forest with some degree of freedom. The
captive rhinoceros, on the other hand, seems from Bishop Heber's
account ^^ to breed in India far more readily than the elephant.
Four wild species of the horse genus have bred in Europe, though
here exposed to a great change in their natural habits of life ; but
the species have generally been crossed one with another. Most of

" Du Rut, ' Aunales du Museum,' 1863, vol. i. pp. 99, 193 ; vol. ii. p.

1807, torn. ix. p. 120. 113.

12 ' Saugethiere von Paraguay,' *•* ' Embassy to the Court of Ava/

1830, s. 49, 106, 118, 124, 201, 2u8, vol. i. p. 534.
249, 265, 327, i^ ' Journal,' vol. i. p. 213.

1* ' The Naturalist on the Amazons,'

Chap. XVIIl. CHANGED CONDITIONS. 133

the members of the pig family breed readily in our menageries ;
even the Eed Eiver hog {Potamochcerus penicillatus), from the
sweltering plains of West Africa, has bred twice in the Zoological
Gardens. Here also the Peccary {Dicotyles torquatus) has bred
several times ; but another species, the D. lahiatus, though ren-
dered so tame as to be half-domesticated, is said to breed so rarely
in its native country of Paraguay, that according to Eengger ^^
the fact requires confirmation. Mr. Bates remarks that the tapir,
though often kept tame in Amazonia by the Indians, never
breeds.

Euminants generally breed quite freely in England, though
brought from widely diiferent climates, as may be seen in the
Annual Eeports of the Zoological Gardens, and in the Gleanings
from Lord Derby's menagerie.

The Carnivora, with the exception of the Plantigrade division,
breed (though with capricious exceptions) about half as freely as
ruminants. Many species of Felidie have bred in various mena-
geries, although imported from diverse climates and closely con-
fined. Mr, Bartlett, the present superintendent of the Zoological
Gardens,^^ remarks that the lion appears to breed more frequently
and to bring forth more young at a birth than any other species of
the family. He adds that the tiger has rarely bred ; " but there
are several well-authenticated instances of the female tiger breed-
ing with the lion." Strange as the fact may appear, many animals
under confinement unite with distinct siDC'cies and produce hj brids
quite as freely as, or even more freely than, with their own species.
On inquiring from Dr. Falconer and others, it appears that the
tiger when confined in India does not breed, though it has been
known to couple. The chetah (Felis juhatd) has never been
known by Mr. Bartlett to breed in England, but it has bred at
Frankfort ; nor does it breed in India, where it is kept in large
numbers for hunting ; but no pains would be taken to make them
breed, as only those animals which have hunted for themselves in
a state of nature are serviceable and worth training.^* According
to Eengger, two species ofwildcatsinParaguay, though thoroughly
tamed, have never bred. Although so many of the Felidse breed
readily in the Zoological Gardens, yet conception by no means
always follows union : in the nine-year Report, various species are
specified which were observed to couple seventy-three times, and
no doubt this must have passed many times unnoticed ; yet from
the seventy-three unions only fifteen births ensued. The Carnivora
in the Zoological Gardens were formerly less freely exposed to the
air and cold than at present, and this change of treatment, as I was
assured by the former superintendent, Mr. Miller, greatly increased
their fertility. Mr. Bartlett, and there cannot be a more cajDable

>« ' Saugethiere,' s. 327. 140,

" On the Breeding of the Larger ^^ Sleemai^'s 'I^ambles in Ipdia,'

Felidae, ' Proc. Zoolog. Soc.,' 1861, p. vol. ii. p. 10.

28

134 STERILITY FROM Chap. XVIIL

judge, says, " it is remarkable that lions breed more freely in
" travelling collections than in the Zoological Gardens ; probably
" the constant excitement and irritation produced by moving from
" place to place, or change of air, may have considerable influence
" in the matter."

Many members of the Dog family breed readily when confined.
The Dhole is one t)f the most untamable animals in India, yet a
pair kept there by Dr. Falconer produced young. Foxes, on the
other hand, rarely breed, and I have never heard of such an occur-
rence with the European fox: the silver fox of North America
{Can is argentatus), however, has bred several times in the Zoo-
logical Gardens. Even the otter has bred there. Every one
knows how readily the semi-domesticated ferret breeds, though
shut up in miserably small cages ; but other species of Viverra and
Paradoxurus absolutely refuse to breed in the Zoological Gardens.
The Genetta has bred both here and in the Jardin des Plantes, and
produced hybrids. The Berpestesfaaciatus has likewise bred ; but I
was formerly assured that the H. grisetts, though many were kept
in the Gardens, never bred.

The Plantigrade Carnivora breed under confinement much less
freely than other Carnivora, although no reason can be assigned
fv>r this fact. In the nine-year Eeport it is stated that the bears
had been seen in the Zoological Gardens to couple freely, but
previously to 1848 had most rarely conceived. In the Eeports
published since this date three species have produced young
(liybrids in one case), and, wonderful to relate, the white Polar
bear has produced young. The badger (Meles tains) has bred
several times in the Gardens ; but I have not heard of this occurring
elsewhere in England, and the event must be very rare, for an
instance in Germany has been thought worth recording. ^^ In
Paraguay the native Nasua, though kept in pairs during many
years and perfectly tamed, has never been known, according to
]iengger, to breed or show any sexual passion ; nor, as I hear from
Mr. Bates, does this animal, or the Cercoleptes, breed in Amazonia.
Two other plantigrade genera, Procyon and Gulo, though often
kept tame in Paraguay, never breed there. In the Zoological
Gardens species of Nasua and Procyon have been seen to couple;
but they did not produce young.

As domesticated rabbits, guinea-pigs, and white mice breed
so abundantly when closely confined under various climates, it
might have been thought that most other members of the Rodent
order would have bred in captivity, but this is not the case.
It deserves notice, as showing how the capacity to breed sometimes
goes by affinity, that the one native rodent of Paraguay, which
there breeds freely and has yielded successive generations, is the
Cavia aperea; and this animal is so closely allied to the guinea-pig.

IB Wiegmann's ' Archiv fiir Naturgesch.,' 1837, s. 162.

Chap. XVIII.

CHANGED CONDITIONS.

135

that it has been erroneously thought to be the parent form.^*' In
the Zoological Gardens, some rodents have coupled, but have never
produced young ; some have neither coupled nor bred ; but a few
have bred, as the porcupine more than once, the Barbary mouse,
lemming, chinchilla, and agouti {Dasyprocta a(juti) several times.
This latter animal has also produced young in Paraguay, though
they were born dead and ill-formed ; but in Amazonia, according
to Mr. Bates, it never breeds, though often kept tame about the
houses. Nor does the paca (Ccelogenys paca) breed there. The
common hare when confined has, I believe, never bred in EurojDe ;
though, according to a recent statement, it has crossed with the
rabbit.^^ I have never heard of the dormouse breeding in confine-
ment. But squirrels offer a more curious case : with one exception,
no species has bred in the Zoological Gardens, yet as many as
fourteen individuals of S. palmarum were kept together during
several years. The S. cinera has been seen to couple, but it did
not produce young ; nor has this species, when rendered extremely
tame in its native country, North America, been ever known to
breed.^^ At Lord Derby's menagerie squirrels of many kinds were
kept in numbers, but Mr. Thompson, the superintendent, told me
that none had ever bred there, or elsewhere as far as he knew.
I have never heard of the English squirrel breeding in confinement.
But the species which has bred more than once in the Zoological
Gardens is the one which perhaps might have been least expected,
namely, the flying squirrel (Sciuropterus volucella) : it has, also,
bred several times near Birmingham ; but the female never pro-
duced more than two young at a birth, whereas in its native
American home she bears from three to six young,^^

Monkeys, in the nine-year Eeport from the Zoological Gardens,
are stated to unite most freely, but during this period, though
many individuals were kept, there were only seven births. I have
heard of only one American monkey, the Ouistiti, breeding in
Europe.^ A Macacus, according to Flourens, bred in Paris ; and

^^ Ren^ger, * Saugethiere,' &c., s.
276. On the parentage of the guinea-
pig, see also Isid. Geoffrey St.-Hilaire,
' Hist. Nat. Gen.' I sent to Mr. H.
Denny of Leeds the lice which I col-
lected from the wild aperea in La
Plata, and he informs me that they
belong to a genus distinct from those
found on the guinea-pig. This is
imi)ortant evidence that the aperea is
not the parent of the guinea-pig ; and
is worth giving, as some authors erro-
neously suppose that the guinea-pig
since being domesticated has become
sterile when crossed with the aperea.

*' Although the existence of the

Leporides, as described by Dr. Broca
(' Journal de Phys.,' torn. ii. p. 370),
has been positively denied, yet Dr. Pi-
geaux (' Annals and Mag. of Nat.
Hist.' vol. XX., 1867, p. 75) affirms that
the hare and rabbit have produced
hybrids.

^2 ' Quadrupeds of North America,
by Audubon and Bachnian, 1846, p.
268.

23 Loudon's ' Mag. of Nat. Hist.,'
vol. ix., 1836, p. 571 ; Audubon and
Bachman's ' Quadrupeds of North
America,' p. 221.

2* Flourens, ' De I'lnstinct,' &o.,
1845, p. 88.

136

STERILITY FROM

Chap. a. f UL

more than one species of this genns has produced young in London,
especially the Macacus rhesus, which everywhere shows a special
capacity to breed under confinement. Hybrids have been produced
both in Paris and London from this same genus. Tlie Arabian
baboon, or Cynocephalus liamadryas^'" and a Cercopithecus have
bred in the Zoological Gardens, and the latter species at the Duke
of Northumberland's. Several members of the family of Lemurs
have produced hybrids in tlie Zoological Gardens. It is much
more remarkable that monkeys very rarely breed when confined
in their native country ; thus the Cay (Ce6«s ftzaroe) is frequently
and completely tamed in Paraguay, but Eengger ^'^ says that it breeds
so rarely, that he never saw more than two females which had
produced young. A similar observation has been made with respect
to the monkeys which are frequently tamed by the aborigines in
Brazil.^^ In Amazonia, these animals are so often kept in a tame
state, that Mr. Bates in walking through the streets of Para counted
thirteen species ; but, as he asserts, they have never been known to
breed in captivity.-^

Birds.

Birds offer in some respects better evidence than quadrupeds,
from their breeding more rapidly and being kept in greater
numbers.^^ We have seen that carnivorous animals are more
fertile under confinement than most other mammals. The reverse
holds good with carnivorous birds. It is said^'^ that as many
as eighteen species have been used in Europe for hawking, and
several others in Persia and India ; ^^ they have been kept in their
native country in the finest condition, and have been flown during
six, eight, or nine years ; ^^ yet there is no record of their having
ever produced young. As these birds were formerly caught whilst
young, at great expense, being imported from Iceland, Norway,

2^ See ' Annual Reports Zoolog.
Soc' 1855, 1858, 1863, 1864; 'Times'
newspapei*, Aug. 10th, 18-t7 ; Flou-
rens, ' De ITnstinct,' p. 85.

s" ' Saugethiere,' &c., s. 34, 49.

2^ Art. Brazil, 'Penny Cyclop.,' p.
363.

28 < The Naturalist on the Amazons,'
vol. i. p. 99.

^' A list of the species of birds
which have bred in the Zoological
Gardens from 1848 to 1867 inclusive
has been, published by Mr. Sclater
in ' Proc. Zoolog. Soc.,' 1869, p. 626,
since the first edition of this work
appeared. Of Columbae 51 species
have been kept, and of Anseres 80
species, and in both these families, 1

species in 2*6 have bred at least once
in the 20 years. Of Gallina3, 83
species have been kept, and 1 in 2*7
have bred ; of 57 Oral la?, 1 in 9 have
bred; of 110 Prehensores, 1 in 22
have bred ; of 178 Passeres, 1 in
25*4 have bred; of 94 Accipitres,
1 in 47 have bred ; of 25 Picaria;, and
of 35 Herodiones, not one species in
either group has bred.

^* ' Encyclop. of Rural Sports,' p.
691.

^^ According to Sir A. Burnes
(' Cabool,' &c,, p. 51), eight species
are used for hawking in Sinde.

32 Loudon's ^Mag. of Nat. Hist.,
vol. vi., 1833, p. 110.

Chap. XYIII. CHANGED CONDITIONS. 137

and Sweden, there can be little doubt that, if possible, they would
have been propagated. In the Jardin des Plantes, no iDJrd of prey
has been known to couple.^^ No hawk, vulture, or owl has ever
produced fertile eggs in the Zoological Gardens, or in the old Surrey
Gardens, witli the exception, in the former j^lace on one occasion,
of a condor and a kite {Milvus iiiyer). Yet several species, namely,
the Aquila funca, Balicttus Jeucocephalus, Falco tinnuncu/tcs, F. sub-
biiteo, and L'ufeo vulgaris, have been seen to couple in the Zoological
Gardens. Mr. Morris ^^ mentions as a unique fact that a kestrel
{Falco tinnunculus) bred in an aviary. The one kind of owl which
has been known to couple in the Zoological Gardens was the Eagle
Owl (Bicho mnximm) ; and this species shows a special inclination
to breed in captivity; for a pair at Arundel Castle, kept more
nearly in a state of nature " than ever fell to the lot of an animal
deprived of its liberty," ^^ actually reared their young. Mr. Gurney
has given another instance of this same owl breeding in confinement ;
and he records the case of a second species of owl, the Strixjiasserina,
breeding in captivity.^"^

Of the smaller graminivorous birds, many kinds have been kept
tame in their native countries, and have lived long ; yet, as the
highest authority on cage-birds-'^'' rem.arks, their propagation is
" uncommonly difficult." The canary-bird shows that there is no
inherent difficulty in these birds breeding freely in confinement ;
and Audubon says^** that the Fringilla (JSjpiza) ciris of North
America breeds as perfectly as the canary. The difficulty with
the many finches which have been kept in confinement is all the
more remarkable as more than a dozen species could be named
which have yielded hybrids with the canary; but hardly any
of these, with the ex'^eption of the siskin ( Fringilla spimis), have
reproduced their own kind. Even the bullfinch {Loxia pyrrJmla)
has bred as frequently with the canary, though belonging to
a distinct genus, as with its own species.^^ With respect to the
skylark (Alauda arverisis), I have heard of birds living for seven
years in an aviary, which never produced young; and a great
London bird-fancier assured me that he had never known an
instance of their breeding ; nevertheless one case has been recorded.^*^
In the nine-year Eeport from the Zoological Society, twenty-four

^^ F. Cuvier, ' Annal. du Museum,' ^® ' Ornithological Biography,' vol.

torn. ix. p. 128. V. p. 517.

2* ' The Zoologist,' vol. vii.-viii., ^^ A case is rocor-led in ' The Zoo-

1849-50, p. 2648. legist,' vol. i.-ii., 1843-45, p. 453. For

^^ Knox, ' Ornithological Ramhies the siskin breeding, vol. iii.-iv., 1845-

in Sussex,' p. 91. 4(5, p. 1075. Bechstein, ' Stuben-

^^ 'The Zoologist,' vol. vii.-viii., v5gel,' s. 139, speaivs of bullfinches

1849-50, p. 2566 ; vol. ix.-x., 1851-2, making nests, but rarely producing

p. 3207. youuo;.

" Bechstein, 'Naturgesch.derStu- ^^ Yarrell's 'Hist. British Birds,'

benvogel,' 1840, s. 20. 1839, vol. i. j-. 412.

138

STERILITY FROM

Chap. XVIIl.

lusessorial species are enumerated which had not bred, and of
these only four were known to have coupled.

Parrots are singularly long-lived birds ; and Humboldt mentions
the curious fact of a parrot in South America, which spoke the
language of an extinct Indian tribe, so that this bird preserved
the sole relic of a lost language. Even in this country there is
reason to believe ^^ that parrots have lived to the age of nearly
one hundred years ; yet they breed so rarely, though many have been
kept in Europe, that the event has been thought worth recording
in the gravest publications.'*^ Nevertheless, when Mr. Buxton
turned out a large number of parrots in Norfolk, three pairs bred
and reared ten young birds in the course of two seasons ,• and this
success may be attributed to their free life.'*^ According to Bechstein **
the African Fsittacus erithacus breeds oftener than any other species
in Germany : the P. macoa occasionally lays fertile eggs, but rarely
succeeds in hatching them; this bird, however, has the instinct
of incubation sometimes so strongly developed, that it will hatch
the eggs of fowls or pigeons. In the Zoological Gardens and in
the old Surrey Gardens some few species have coupled, but, with
the exception of three species of parrakeets, none have bred. It
is a much more remarkable fact that in Guiana parrots of two
kinds, as I am informed by Sir E. Schomburgk, are often taken
from the nests by the Indians and reared in large numbers ; they
are so tame that they fly freely about the houses, and come when
called to be fed, like pigeons ; yet he has never heard of a single
instance of their breeding.'*^ In Jamaica, a resident naturalist,
Mr. K. Hill,*^ says, "no birds more readily submit to human
" dependence than the parrot- tribe, but no instance of a parrot
" breeding in this tame life has been known yet." Mr. Hill specifies
a number of other native birds kept tame in the West Indies, which
never breed in this state.

The great pigeon family offers a striking contrast with the parrots :
in the nine-year Report thirteen species are recorded as having
bred, and, what is more noticeable, only two were seen to couple
without any result. Since the above date every annual Report
gives many cases of various pigeons breeding. The two magnificent
crowned pigeons (Go^<ra coronata and vic^or/ce) produced hybrids;

** Loudon's ' !Mag. of Nat. History,'
vol. xix., 1836, p. 347.

<2 ' Memoires du Museum d'Hist.
Nat.,' torn. X. p. 314: five cases of
parrots breeding in France are here
recorded. See also ' Report Brit.
Assoc. Zoolog.,' 1843.

•'^ ' Annals and Mag. of Nat. Hist.,'
Nov. 1868, p. 311.

** ' Stubenvogel,' s. 105, 83.

♦' Dr. Hancock remarks (' Charles-

worth's Mag. of Nat. Hist.' vol.
ii., 1838, p. 492), "it is singular
that, amongst the numerous useful
birds that are indigenous to Guiana,
none are found to propagate among
the Indians ; yet the common fowl is
reared in abundance throughout the
country."

4« 'A Week at Pert Royal,' 1855,
p. 7.

Chap. XV III-

CHANGED CONDITIONS.

139

nevertheless, of the former species more than a dozen birds were
kept, as I am informed by Mr. Crawfurd, in a park at Penang,
under a perfectly well-adapted climate, but never once bred. The
Columha miyratoria in its native country. North America, invariably
lays two eggs, but in Lord Derby's menagerie never more than
one. The same fact has been observed with the C. Uucocephala.*'^

Gallinaceous birds of many genera likewise show an eminent
capacity for breeding under captivity. This is particularly the case
with pheasants, yet our English sjDecies seldom lays more than ten
eggs in confinement ; whilst from eighteen to twenty is the usual
number in the wild state.^^ With the GrallinaceaB, as with all other
orders, there are marked and inexplicable exceptions in regard to
the fertility of certain species and genera under confinement.
Although many trials have been made with the common partridge,
it has rarely bred, even when reared in large aviaries ; and the hen
will never hat<5h her own eggs.*^ The American trite of Guaus
or Cracidse are tamed with remarkable ease, but are very shy
breeders in this country;^ but with care various species were
formerly made to breed rather freely in Holland.^^ Birds of this
tribe are often kept in a perfectly tamed condition in their native
country by the Indians, but they never breed.^^ It might have been
expected that grouse from their habits of life would not have bred in
captivity, more especially as they are said soon to languish and
die.^ But many cases are recorded of their breeding : the caper-
cailzie (Tetrao urogallus) has bred in the Zoological Gardens; it
breeds without much dilficulty when confined in Norway, and in
Russia five successiA^e generations have been reared : Tetrao tdrix
has likewise bred in Norway ; T. scoticus in Ireland ; T. umbeUus at
Lord Derby's; and T. cupido in North America.

It is scarcely possible to imagine a greater change in habits than
that which the members of the ostrich family must sulfer, when
cooped up in small enclosures under a temperate climate, after
freely roaming over desert and tropical plains or entangled forests ;

*' Audubon, * American Ornith-
ology,' vol. V. pp. 552, 557.

** Moubray on Poultry, 7th edit,,
p. 133.

*^ Temminck, ' Hist. Nat. Gen. des
Pigeons,' &c., 1813, torn. iii. pp. 288,
382; 'Annals and Mag. of Nat. Hist.,'
vol xii., 1843, p. 453. Other species
of partridge have occasionally bred ;
as the red-legged (P. rubra), when
kept in a large court in France {see
'Journal de Physique,' torn. xxv. p.
294), and in the Zoological Gardens
in 1856.

" Rev. E. S. Dixon, 'The Dove-
cote,' 1851, pp. 243-252.

*' Temminck, ' Hist. Nat. Gen. des
Pigeons,' kc, torn. ii. pp. 456, 458 ;
torn. iii. pp. 2, 13, 47.

*- Bates, 'The Naturalist on the
Amazons,' vol. i. p. 193 ; vol. ii. p.
112.

S3 Temminck, ' Hist. Nat. Gen.,' &c.,
torn. ii. p. 125. For Tetrao urogallus,
see L. Lloyd, 'Field Sports of North
of Europe,' vol. i. pp. 287, 314 ; and
' Bull, de la Soc. d'Acclimat.,' torn,
vii., 1860, p. 600. For T. scoticns,
Thompson, 'Nat. Hist, of Ireland,'
vol. ii. 1850, p. 49. For T. cupido.
' Boston Journal of Nat. Hist.,' vol.
iii. p. 199.

240 STERILITY FROM Chap. XVIIL

yet almost all the kinds have frequently produced young in the
various European menageries, even the mooruk {Casuarius bennetii)
from New Ireland. The African ostrich, though perfectly healthy
and living long in the South of France, never lays more than from
twelve to fifteen eggs, though in its native country it lays from
twenty-five to thirty.-^* Here we have another instance of fertility
impaii-ed, but not lost, under confinement, as with the flying
squirrel, the hen-pheasant, and two species of American pigeons.

Most Waders can be tamed, as the Kev. E. S. Dixon informs me,
with remarkable facility ; but several of them are short-lived under
confinement, so that their sterility in this state is not surprising.
The cranes breed more readily than other genera : Orvs montigresia
has bred several times in Paris and in the Zoological Gardens, as
has G. cinerea at the latter place, and G. antigone at Calcutta. Of
other members of this great order, Tttrapteryx paradisca has bred
at Knowsley, a Porphyrio in Sicily, and the Gallimda chloropus in
the Zoological Gardens. On the other hand, several birds belonging
to this order will not breed in their native coimtry, Jamaica ; and
the Psophia, though often kept by the Indians of Guiana about
their houses, " is seldom or never known to breed." ^^

The members of the great Duck family breed as readily in
confinement as do the Columbse and Gallinse ; and this, considering
their aquatic and wandering habits, and the nature of their food,
could not have been anticipated. Even some time ago above two
dozen species had bred in the Zoological Gardens ; and M. Selys-
Longchampshas recorded the production of hybrids from forty-four
different members of the family ; and to these Professor Newton has
added a few more cases.^^ " There is not," says Mr. Dixon,^^ " in
the wide world, a goose which is not in the strict sense of the word
domesticable ;" that is, capable of breeding under confinement ;
but this statement is probably too bold. The capacity to breed
sometimes varies in individuals of the same species; thus Audubon^^
kept for more than eight years some wild geese {Anser canadensis'),
but they would not mate; whilst other individuals of the same
species produced young during the second year. I know of but one
instance in the whole family of a species which absolutely refuses
to breed in captivity, namely, the Dendrocygna viduata, although,
according to Sir E. Schomburgk,^^ it is easily tamed, and is
frequently kept by the Indians of Guiana. Lastly, with respect

*■* Marcel de Sevres, ' Annales des ' Report Asiatic Soc. of Bengal,' May

Sci. Nat.,' 2nd series, Zoolog., torn. 1855.

xiii. p. 175. ^^ Prof. Newton, in * Proc. Zoolog.

" Dr. Hancock, in ' Charlesworth's Soc.,' 1860, p. 336.

Mag. of Nat. Hist.,' vol. ii., 1838, p. ^^ 'The Dovecote and Aviary,' p,

49 1 ; R. Hill, ' A Week at Port Royal,' 428.

p. 8 ; ' Guide to the Zoological Gardens,' ^® ' Ornithological Biography,' vol.

by P. L. Sclater, 1859, pp. 11, 12; iii. p. 9.

* The Knowsley Menagerie,* bv Dr. *^ ' Geograph. Journal,' vol. xiii.,

Gray, 1846, pi. xiv. ; E. lilyth, 1844 '). 32

CuAT. XVIII. CHANGED CONDITIONS. 141

to Gulls, tlioiigh mai^ have been kept in the Zoological Gardens
and in the old Surrey Gardens, no instance "was known before the
year 1818 of their coupling or breeding ; but since that period the
herring gull (Larus argentatus) has bred many times in the
Zoological Gardens and at Knowsley.

There is reason to believe that insects are affected by confinement
like the higher animals. It is well known that the Sphingidae
rarely breed when thus treated. An entomologist^*' in Paris kept
twenty-five specimens of ISaturnia pyri, but did not succeed in
getting a single fertile egg. A number of females of Orthosia munda
and of Mamestra snasa reared in confinement were unattractive to
the males.''^ Mr. Newport kept nearly a hundred individuals of
two sf)ecies of Vanessa, but not one j^aired ; this, however, might
have been due to their habit of coupling on the wing.^^ Mr.
Atkinson could never succeed in India in making the Tarroo silk-
moth breed in confinement.^^ It appears that a number of moths,
especially the Sphingidae, when hatched in the autumn out of their
proper season, are completely barren; but this latter case is still
involved in some obscurity.^*

Independently of the fact of many animals under confine-
ment not coupling, or, if they couple, not producing young,
there is evidence of another kind that their sexual functions
are disturbed. For many cases have been recorded of the
loss by male birds when confined of their characteristic plu-
mage. Thus the common linnet (Linota cannabina) when
caged does not acquire the fine crimson colour on its breast,
and one of the buntings {Emheriza passerina) loses the black
on its head. A Pyrrhula and an Oriolus have been observed
to assume the quiet plumage of the hen-bird ; and the Falco
alhidus returned to the dress of an earlier age.^^ Mr. Thomp-
son, the superintendent of the Knowsley menagerie, informed
me that he had often observed analogous facts. The horns
of a male deer (Cerviis canadensis) during the voyage from
America were badly developed ; but subsequently in Paris
perfect horns were produced.

^o Loudon's ' Mag. of Nat. Hist.,' 5764 ; and Dr. Wallace, in ' Proc.

vol. v., 1832, p. 153. Entomolog. Soc.,' June 4th, 1860, p.

«» ' Zoologist,' vols, v.-vi., 1847-48, 119.
p. 1660. *^^ Yarrell's ' British Birds,' vol. i.

®2 ' Transact. Entomolog. Soc.,' vol. p. 506 ; Bechstein, ' Stubenvogel,' s.

iv., 1845, p. 60. 185 ; ' Philosoph. Transact.,' 1772, p.

*' 'Transact. Linn. Soc.,' vol. vii. 271. Bronn (' Geschichte der Natur,'

p. 40. Band ii. s. 96) has collected a number

^* See an interesting paper by Mr. of cases. For the case of the deer, see

Newman, in the 'Zoologist,' 1857, p. ' Penny Cyclop.,' vol. viii. p. 350.

142 STEEILITY FK03I Cha?. XYIII,

When conception takes place under confinement, the young
are often born dead, or die soon, or are ill-formed. This
frequently occurs in the Zoological Gardens, and, according to
Eengger, with native animals confined in Paraguay. The
mother's milk often fails. We may also attribute to the dis-
turbance of the sexual functions the frequent occurrence of
that monstrous instinct which leads the mother to devour her
own offspring, — a mysterious case of perversion, as it at first
appears.

Sufficient evidence has now been advanced to prove that
animals when first confined are eminently liable to suffer in
their reproductive systems. We feel at first naturally inclined
to attribute the result to loss of health, or at least to loss of
vigour ; but this view can hardly be admitted when we
reflect how healthy, long-lived, and vigorous many animals
are under captivity, such as parrots, and hawks when used for
hawking, chetahs when used for hunting, and elephants. The
reproductive organs themselves are not diseased ; and the
diseases, from which animals in menageries usually perish,
are not those which in any way affect their fertility. No
domestic animal is more subject to disease than the sheep, yet
it is remarkably prolific. The failure of animals to breed
under confinement has been sometimes attributed exclusively
to a failure in their sexual instincts : this may occasionally
come into play, but there is no obvious reason why this
instinct should be especially liable to be affected with per-
fectly tamed animals, except, indeed, indirectly through the
reproductive S3^stem itself being disturbed. Moreover,
numerous cases have been given of various animals which
couple freely under confinement, but never conceive; or, if
they conceive and produce young, these are fewer in number
than is natural to the species. In the vegetable kingdom
instinct of course can pla}^ no part ; and we shall j)resently see
that plants when removed from their natural conditions are
affected in nearly the same manner as animals. Change of
climate cannot be the cause of the loss of fertility, for, whilst
many animals imported into Europe from extiemely different
climates breed freely, many others when confined in their
native land are completely sterile. Change of food cannot be

Chap. XVIII. CHANGED CONDITIONS. 143

the chief cause ; for ostriches, ducks, and man}' other animals,
which must have undergone a great change in this respect,
breed freely. Carnivorous birds when confined are extremely
sterile, whilst most carnivorous mammals, except plantigrades,
are moderately fertile. IS or can the amount of food be the
cause ; for a sufficient supply will certainly be given to valuable
animals ; and there is no reason to suppose that much more
food would be given to them than to our choice domestic
productions which retain their full fertility. Lastly, we may
infer from the case of the elephant, chetah, various hawks, and
of many animals which are allowed to lead an almost free life
in their native land, that want of exercise is not the sole cause.
It would appear that any change in the habits of life, what-
ever these habits may be, if great enough, tends to affect in
an inexplicable manner the powers of reproduction. The
result depends more on the constitution of the species than on
the nature of the change ; for certain whole groups are
affected more than others ; but exceptions always occur, for
some species in the most fertile groups refuse to breed, and
some in the most sterile groups breed freely. Those animals
which usually breed freely under confinement, rarely breed,
as I was assured, in the Zoological Gardens, within a year or
two after their first importation. When an animal which is
generally sterile under confinement happens to breed, the
young apparently do not inherit this power : for had this
been the case, various quadrupeds and birds, which are
valuable for exhibition, would have become common. Dr.
Broca even affirms ^^ that many animals in the Jardin des
Plantes, after having produced young for three or four suc-
cessive generations, become sterile ; but this may be the
result of too close interbreeding. It is a remarkable circum-
stance that many mammals and birds have produced hybrids
under confinement quite as readily as, or even more readily
than, they have procreated their own kind. Of this fact many
instances have been given ; ^^ and we are thus reminded of
those plants which when cultivated refuse to be fertilised by

®® 'Journal de Physiologie,' torn. svbject, see F. Cuvier, in * Annales da
U. p. 347. Museum,' torn. xii. p. 119.

•^ For additional evidence on this

144

STERILITY FROM

Chap. XVIU.

their own jjolleu, "but can easily "be fertilised \>y that of a
distinct species. Finally, we must conclude, limitt d as the
conclusion is, that changed conditions of life have an especial
power of acting injuriously on the reproductive system. The
whole case is quite peculiar, for these organs, though not
diseased, are thus rendered incapable of performing their
proper functions, or perform them imperfectly.

Sterility of Doim'sficated Animals from chanrjed conditions. — "With
respect to domesticated animals, as their domestication mainly
depends on the accident of their breeding freely under captivity,
we ought not to expect that their reproductive system would be
affected by any moderate degree of change. Those orders of
quadrupeds and birds, of which the wild species breed most readily
in our menageries, have afforded us the greatest number of domes-
ticated productions. Savages in most parts of the world are fond
of taming animals ;^^ and if any of these regularly produced young,
and were at the same time useful, they would be at once domesti-
cated. If, when their masters migrated into other countries, they
were in addition found capable of withstanding various climates,
they would be still more valuable; and it appears that the animals
which breed readily in captivity can generally withstand different
climates. Some few domesticated animals, such as the reindeer and
camel, offer an exception to this rule. Many of our domesticated
animals can bear with imdiminished fertility the most unnatural
conditions; for instance, rabbits, guinea-pigs, and ferrets breed in
miserably confined hutches. Few European dogs of any kind
withstand the climate of India without degenerating, but as long
as they survive, they retain, as I hear from Dr. Falconer, their
fertility ; so it is, according to Dr. Daniell, with English dogs
taken to Sierra Leone, The fowl, a native of the hot jungles of
India, becomes more fertile than its parent-stock in every quarter
of the world, until we advance as far north as Greenland and
Northern Siberia, where this bird will not breed. Both fowls and
pigeons, which I received during the autumn direct from Sierra
Leone, were at once ready to couple.^ I have, also, seen pigeons

*^ Numerous instances could be
given. Thus Livingstone ('Travels,'
p. 217) states that the King of the
Barotse, an inland tribe which never
had any communication with white
men, was extremely fond of taming
animals, and every young antelope was
brought to him. Mr. Galton informs
Qie that the Dnmaras are likewise
fond cf lieeping pets. The Indians of
South America follow the same habit.
Capt. Wilkes states that the Poly-

nesians of the Samoan Islands tamed
pigeons; and the New Zealanders, as
Mr. ]\Iantell informs me, kept various
kinds of birds.

°^ For analogous cases with the
fowl, see Reaumur, ' L'Art de faire
Eclore,' &c., 1749, p. 243 ; and Col.
Sykes, in * Proc. Zoolog. Soc.,' 1832,
&C. With respect to the fowl not
breeding in northern regions, see
Latham's ' Hist, of P>irds,' vol. viii.,
1823, p. 169.

CiiAr. XVIII. CHANGED CONDITIONS. 145

breeding as freely as the common kinds within a year after their
importation from the upper Nile. The guinea-fowl, an aboriginal
of the hot and dry deserts of Africa, whilst living under our damp
and cool climate, produces a large supply of eggs.

Nevertheless, our domesticated animals under new conditions
occasionally show signs of lessened fertility. Eoulin asserts that
in the hot valleys of the equatorial Cordillera sheep are not fully
fecund ;'° and according to Lord Somerville,^^ the merino-sheep
which he imported from Spain were not at first perfectly fertile. It
is said^^ that mares brought up on dry food in the stable, and
turned out to grass, do not at iirst breed. The peahen, as we have
seen, is said not to lay so many eggs in England as in India. It
was long before the canary-bird was fully fertile, and even now first-
rate breeding birds are not common,'^^ In the hot and dry province
of Delhi, as I hear from Dr. Falconer, the eggs of the turkey,
though placed under a hen, are extremely liable to fail. According
to Eoulin, geese taken to the lofty plateau of Bogota, at first laid
seldom, and then only a few eggs ; of these scarcely a foui'th were
hatched, and half the young birds died ; in the second generation
they were more fertile; and when Eoulin wrote they were becoming
as fertile as our geese in Europe. With respect to the valley of
Quito, LIr. Orton says :'^* '' the only geese in the valley are a few
imported from Europe, and these refuse to propagate." In the
Philii^pine Archipelago the goose, it is asserted, will not breed or even
lay eggs.'^ A more curious case is that of the fowl, wliich, accord-
ing to Eoulin, when first introduced would not breed at Cusco in
Bolivia, but subsequently became quite fertile ; and the English Game
fowl, lately introduced, had not as yet arrived at its full fertihty,
for to raise two or three chickens from a nest of eggs was thought
fortunate. In Europe close confinement has a marked eifect on the
fertility of the fowl : it has been found in France that with fowls
allowed considerable freedom only twenty per cent, of the eggs failed ;
when allowed less freedom forty per cent, failed ; and in close con-
finement sixtv out of the hundred were not hatched.'^^ So we see that
unnatural and changed conditions of life produce some effect on the
fertility of our most thoroughly domesticated animals, in the same
manner, though in a far less degree, as with captive wild animals.

It is by no means rare to find certain males and females which will
not breed together, though both are known to be perfectly fertile
with other males and females. We have no reason to suppose that
this Is caused by these animals having been subjected to any change
in their habits of life ; therefore such cases are hardly related to our
present subject. The cause ajjparently lies in an innate sexual in-

^'"' Mem. par divers Savans," 'Acad. "■* 'The Andes and the .\mazcn,'

des Sciences,' torn, vi., 183-5, p. 347. 1870, p. 107.

^^ Youatt on Sheep, p. 181. ^^ Crawfurd's ' Descriptive Diet, of

^^ J. Mills, 'Treatise on Cattle,' the Indian islands,' 1856, p. 145.
1776, p. 72. "6 ' Bull, de la Soc. d'Acclimat.,

" Bechstein, ' Stubenvogel,' s. 242. torn, ix., 1862, pp. 380, 384.

146 STERILITY FROM Chap. XVIII.

compatibility of the pair which are matched. Several instances have
been communicated to me by Mr. W. C. Spooner (well known for his
essay on Cross-breeding), by Mr. Eyton of Eyton, by Mr. Wicksted
and other breeders, and especially by Mr. Waring of Chelsfield, in
relation to horses, cattle, pigs, foxhounds, other dogs, and pigeons.''^
In these cases, females, which either previously or subsequently were
proved to be fertile, failed to breed with certain males, with whom
it was particularly desired to match them. A change in the con-
stitution of the female may sometimes have occurred before she was
put to the second male ; but in other cases this explanation is hardly
tenable, for a female, known not to be barren, has been unsuccessfully
paired seven or eight times with the same male likewise known to be
perfectly fertile. With cart-mares, which sometimes will not breed
with stallions of pure blood, but subsequently have bred with cart-
stallions, Mr. Spooner is inclined to attribute the failure to the lesser
sexual power of the race-horse. But I have heard from the greatest
breeder of race-horses at the present day, through Mr. Waring, that
*' it frequently occurs with a mare to be imt several times during
" one or two seasons to a jDarticular stallion of acknowledged power,
" and yet prove barren ; the mare afterwards breeding at once with
'' some other horse." These facts are worth recording, as they show,
like so many previous facts, on what slight constitutional differences
the fertility of an animal often depends.

Sterility of Plants from changed Conditions of Life, and from

other causes.

In the vegetable kingdom cases of sterility frequently
occur, analogous Avith those previously given in the animal
kingdom. But the subject is obscured by several circum-
stances, presently to be discussed, namely, the contabescence
of the anthers, as Gartner has named a certain affection —
monstrosities — doubleness of the flower— much-enlarged fruit
--and long-continued or excessive propagation by buds.

It is notorious that many plants in our gardens and hot-houses,
though preserved in the mo.st perfect health, rarely or never pro-
duce seed. I do not allude to plants which run to leaves, from
being kept too damp, or too warm, or too much manured; for
these do not flower, and the case may be wholly different. Nor do
I allude to fruit not ripening from want of heat or rotting from too
much moisture. But many exotic plants, with their ovules and
pollen appearing perfectly sound, will not set any seed. The
sterility in many cases, as I know from my own observation, is
simply due to the absence of the proper insects for carrying the
pollen to the stigma. But after excluding the several cases just

77

For pigeons, see Dr. Chapuis, * Le Pigeon Voyageur Beige,' 1865, p. 66.

Chap. XVIU. CHANGED CONDITIONS. 147

specified, there are many plants in which the reproductive system
has been seriously afiected by the altered conditions of life to
which they have been subjected.

It would be tedious to enter on many details. Linnaeus long
ago observed "^^ that Alpine plants, although naturally loaded with
seed, produce either few or none when cultivated in gardens. But
exceptions often occur : the Draba sylvestris, one of our most
tlioroughly Alpine plants, multiplies itself by seed in Mr. H. C.
Watson's garden, near London ; and Kerner, who has particularly
attended to the cultivation of Alpine plants, found that various
kinds, when cultivated, spontaneously sowed themselves.'^ Many
plants which naturally grow in peat-earth are entirely sterile in our
gardens. I have noticed the same fact with several liliaceous plants,
which nevertheless grew vigoroasly.

Too much manure renders some kinds utterly sterile, as I have
myself observed. The tendency to sterility from this cause runs
in families ; thus, according to Gartner,^^ it is hardly possible to
give too much manure to most Graminese, Cruciferse, and Legu-
minosse, whilst succulent and bulbous-rooted plants are easily
afiected. Extreme poverty of soil is less apt to induce sterility ;
but dwarfed plants of Trifoliuni minus and repens, growing on a
lawn often mown and never manured, were found by me not to
produce any seed. The temperature of the soil, and the season at
which plants are watered, often have a marked effect on their
fertility, as was observed by Kolreuter in the case of Mirabilis.*^
Mr. Scott, in the Botanic Gardens of Edinburgh, observed that
Oiiculiitm divaricatum would not set seed when grown in a basket
in which it throve, but was capable of fertilisation in a pot where
it was a little damper. Pelargonium f id gidum, for many years after
its introduction, seeded freely; it then became sterile; now it is
fertiJe^^ if kept in a dry stove during the winter. Other varieties
of pelargonium are sterile and others fertile without our being able
to assign any cause. Very slight changes in the position of a plant,
whether planted on a bank or at its base, sometimes make all the
difference in its producing seed. Temperature apparently has a
much more powerful influence on the fertility of plants than on
that of animals. Nevertheless it is wonderful what changes some
few plants will withstand with undiminished fertility : thus the
Zephyranthes Candida, a native of the moderately warm banks of the
Plata, sows itself in the hot dry country near Lima, and in Yorkshire

^8 'Swedish Acts,' vol. i., 1739, Chronicle,' 1848, pp. 253, 268, and

p. 3. Pallas riakes the same remark mentions a few which seed,

in his ' Travels '(Eng. translat.), vol. i. ** ' Beitrage zur Kenntniss der

p. 292. Befruchtung,' 1844, s. 333.

^» A. Kerner, 'Die Cultur der Al- ^i 'Nova Acta Petrop.,' 1793, p.

penpflanzen,' 1864, s. 139; Watson's 391.

' Cybele Britannica,' vol. i. p. 131; ^^ 'Cottage Gardener,' 1856, pp

Mr. D. Cameron, also, has written on 4 4, 109.
the culture of Alpine plants in ' Gard.

148 STERILITY FROM CHANGED CONDITIONS. Chap. X\'1U.

resists the severest frosts, and I have seen seeds gathered from pods
"which had been covered with snow during three weeks.**^ Berberis
wallichii, from the hot Khasia range in India, is uninjured by our
sharpest frosts, and ripens its fruit under our cool summers.
Nevertheless, I presume we must attribute to change of climate the
sterility of many foreign plants ; thus, the Persian and Chinese
lilacs {Syringa persica and chinensis), though perfectly hardy
here, never produce a seed ; the common lilac {S. vulgaris) seeds
with us moderately well, but in parts of Germany the capsules
never contain seed.^* Some few of the cases, given in the last
chapter, of self-impotent plants, might have been here introduced,
as their state seems due to the conditions to wliich they have been
subjected.

The liability of plants to be affected in their fertility by slightly
changed conditions is the more remarkable, as the pollen when
once in process of formation is not easily injured ; a plant may be
transplanted, or a branch with flower-buds be cut olf and placed in
water, and the pollen will be matured. Pollen, also, when
once mature, may be kept for weeks or even months.^^ The female
organs are more sensitive, for Gartner ^^ found that dicotyledonous
plants, when carefully removed so that they did not in the least
flag, could seldom be fertilised ; this occurred even with potted
plants if the roots had grown out of the hole at the bottom. In
some few cases, however, as with Digitalis, transplantation did not
prevent fertilisation; and according to the testimony of Mawz,
Brassica rapa, when pulled up by its roots and placed in water,
ripened its seed. Flower-stems of several monocotyledonous plants
uhen cut off and placed in water likewise produce seed. But in
these cases I presume that the flowers had been already fertilised,
for Herbert ^' found with the Crocus that the plants might be re-
moved or mutilated after the act of fertilisation, and would still
perfect their seeds; but that, if transplanted before being fertilised,
the application of pollen was powerless.

Plants which have been long cultivated can generally endure
with undiminished fertility various and great changes ; but not in
most cases so great a change of climate as domesticated animals.
It is remarkable that many plants under these circumstances are
so much affected that the proportion and the nature of their che-
mical ingredients are modified, yet their fertility is unimpaired.
Thus, as Dr. Falconer informs me, there is a great difference in the
character of the fibre in hemp, in the quantity of oil in the seed of

*^ Dr. Herbert, ' Amaryllidaceas,* ' La Variabilite des Especes,' 1868, p.

p. 176, 155,

** Gartner, ' Beitrage zur Kennt- *^ * Beitrage zur Kenntniss,' &c., s.

Diss,' &c., s. 560, 564. 252, 333.

85 * Gardener's Chronicle,* 1844, p. ^7 i Journal of Hort. Soc.,* voL ii.,

215 ; 1850, p. 470. Faivre gives a 1847, p. 83.
good resume on this subject in his

Chap. XVIII. CONTABESCENCE. 149

the Linum, in the proportion of narcotin to morphine in the poppy,
in gluten to starch in wheat, when these plants are cultivated on
the i^lains and on the mountains of India ; nevertheless, they all
remain fully fertile.

Contabescenct:. — Gartner has designated by this term a peculiar
condition of the anthers in certain plants, in which they are sliri-
velled, or become brown and tough, and contain no good pollen.
When in this state they exactly resemble the anthers of the most
sterile hybrids, Gartner,^** in his discussion on this subject, has
shown that plants of many orders are occasionally thus affected ;
but the Caryophyllacese and Liliaceae suffer most, and to these
orders, I think, the Ericaceae may be added. Contabescence varies
in degree, but on the same plant all the flowers are generally affected
to nearly the same extent. The anthers are affected at a very early
period in the flower-bud, and remain in the same state (with one
recorded exception) during the life of the plant. The afft-ction
cannot be cured by any change of treatment, and is propagated by
layers, cuttings, &c., and perhaps even by seed. In contabescent
plants the female organs are seldom affected, or merely became
precocious in their development. The cause of this affection is
doubtful, and is different in differeni cases. Until I read Gartner's
discussion I attributed it, as apparently did Herbert, to the un-
natural treatment of the plants ; but its permanence under chunged
conditions, and the female organs not being affected, seem incom-
patible with this view. The fact of several endemic plants be-
coming contabescent in our gardens seems, at first sight, equally
incompatible with this view; but Kolreuter believes that this is
the result of their transplantation. The contabescent plants of
Dianthus and Verbascum, found wild by Wiegmann, grew on a
dry and sterile bank. The fact that exotic plants are eminently
liable to this affection also seems to show that it is in some manner
caused by their unnatural treatment. In some instances, as with
Silene, Gartner's view seems the most probable, namely, that it is
caused by an inherent tendency in the species to become dioecious.
I can add another cause, namely, the illegitimate unions of hetero-
styled plants, for I have observed seedlings of three species of
Primula and of Lythrum salicaria, which had been raised from
plants illegitimately fertilised by their own-form pollen, with some
or all their anthers in a contabescent state. There is perhaps an
additional cause, namely, self-fertilisation ; for many plants of
Dianthus and Lobelia, which had been raised from self-fertilised
seeds, had their anthers in this state ; but these instances are not
conclusive, as both genera are liable from other causes to this
affection.

Cases of an opposite nature likewise occur, namely, plants with

*' ' Beitrage zur Kenntniss,' &c., s. setzung,* s. 57. Herbert, * Amarylli-
lll et seq. ; Koheuter, 'Zweite Fort- daceae,' p. 355. Wiegmann, ' Ueber
setzuug,' s. 10, 121 ; * Dritte Fort- die Bastarderzeugung,' s. 27.

150

STERILITY.

Chm\ XVIII.

the female organs struck with sterility, whilst the male organs
remain perfect. Dtaidhus japonicus, a Passiflora, and Nicotiana,
have been described by Gartner ^^ as being in this unusual con-
dition.

Monstrosities as a cause of sterility. — Great deYiations of structure,
even when the reproductive organs themselves are not seriously
affected, sometimes cause plants to become sterile. But in other
cases plants may become monstrous to an extreme degree and yet
retain their full fertility. Gallesio, who certainly had great ex-
perience,^^ often attributes sterility to this cause; but it may be
suspected that in some of his cases sterility was the cause, and not
the result, of the monstrous growths. The curious St. Valery apple,
although it bears fruit, rarely produces seed. The wonderfully
anomalous flowers of Begonia friyida, formerly described, though,
they appear fit for fructification, are sterile.^^ Species of Primul i
in which the calyx is brightly coloured are said^^ to be often sterile,
though I have known them to be fertile. On the other hand,
Verlot gives several cases of proliferous flowers which can be pro-
pagated by seed. This was the case with a poppy, which had
become monopetalous by the union of its petals.^^ Another extra-
ordinary poppy, with the stamens replaced by numerous small
supplementary capsules, likewise reproduces itself by seed. This
has also occurred with a plant of ISaxifraga geuin, in which a series
of adventitious carpels, bearing ovules on their margins, had been
developed between the stamens and the normal carpels.'-** Lastly,
with respect to peloric flowers, which depart wonderfully from the
natural structure, — those of Linaria vulgaris seem generally to be
more or less sterile, whilst those before described of Antirrhinum
7nujus, when artificially fertilised with their o^ti pollen, are
perfectly fertile, though sterile when left to themselves, for bees are
unable to crawl into the narrow tubular flower. The peloric
flowers of Corydalis solida, according to Godron,^^ are sometimes
barren and sometimes fertile; wiiilst those of Gloxinia are well
known to yield plenty of seed. In our greenhouse Pelargoniums,
the central flower of the truss is often peloric, and Mr. Masters
informs me that he tried in vain during several years to get seed
from these flowers. I likewise made many vain attempts, but some-
times succeeded in fertilising them with pollen from a normal

^^ ' Bastarderzeugung,' s. 356.

^° ' Teoria della Kiproduzione,*
1816, p. 84; 'Traite du Citrus,' 1811,
p. 67.

91 Mr. C. W. Crock«r, in ' Gard.
Chronicle,' 1861, p. 1092.

" Verlot, 'Des Varietes,' 1865,
p. 80.

«3 Verlot, ibid., p. 88.

** Prof. AUman, Brit. Assoc,
quoted in the ' Phytologi.^t,' vol. ii.

p. 483. Prof. Harvey, on the autho-
rity of Mr. Andrews, who discovered
the plant, informed me that this
monstrosity could be propagated by
seed. With respect to the poppy, see
Prof. Goepi)ert, as quoted in ' Journal
of Horticulture,' July 1st, 1863, p.
171.

»5 'Compter Rendus,' Dec. 19th,
1864, p. 1039.

Chap. XVi.I. DOUBLE FLOWEES. 151

flower of another yariety ; and conversely I several times fertilised
ordinary flowers with peloric pollen. Only once I succeeded in
raising a plant from a peloric flower fertilised by pollen from a
peloric flower borne by another variety ; but the plant, it may be
added, presented nothing particular in its structure. Hence we
may conclude that no general rule can be laid down; but any
great deviation from the normal structure, even when the repro-
ductive organs themselves are not seriously affected, certainly often
leads tc sexual impotence.

Double Flowers. — "When the stamens are converted into petals,
the plant becomes on the male side sterile ; when both stamens
and pistils are thus changed, the plant becomes comjDletely barren.
Symmetrical flowers having numerous stamens and petals are the
most liable to become double, as perhaps follows from all multiple
organs being the most subject to variability. But flowers furnished
with only a few stamens, and others which are asymmetrical in
structure, sometimes become double, as we see with the double
gorse or Ulex, and Antirrhinum. The Compositae bear what are
called double flowers by the abnormal development of the corolla of
their central florets. Doubleness is sometimes connected with
prolification,^'^ or the continued growth of the axis of the flower.
Doubleness is strongly inherited. No one has produced, as Lindley
remarks,^^ double flowers by promoting the perfect health of the
plant. On the contrary, unnatural conditions of life favour their
production. There is some reason to believe that seeds kept during
many years, and seeds believed to be imperfectly fertilised, yield
double flowers more freely than fresh and perfectly fertilised seed.^^
Long-continued cultivation in rich soil seems to be the commonest
exciting cause. A double narcissus and a double Anthemis nohilis,
transplanted into very poor soil, has been observed to become
single ; ^'^ and I have seen a completely double white primrose
rendered permanently single by being divided and transplanted
whilst in full flower. It has been observed by Professor E. Morren
that doubleness of the flowers and variegation of the leaves are
antagonistic states ; but so many exceptions to the rule have lately
been recorded,^*^*^ that, though general, it cannot be looked at as
invariable. Variegation seems generally to result from a feeble or
atrophied condition of the plant, and a large proportion of the
seedlings raised from parents, if both are variegated, usually perish at
an early age ; hence we may perhaps infer that doubleness, which is

"* < Gardener's Chronicle,' 1866, p. cm Journ. of Science,' vol. xxiii. p.

681. 47 ; and Verlot, ' Des V'aiictos,' 186.'),

9' ' Theory of Horticulture,' p. .333. p. 84.

"* Mr. Fair weather, in ' Transact. "'•* Lindley's ' Theory of Horticxil-

Hort. Soc.,' vol. iii. p. 406 : Bosse, ture,' p. 3 3.

quoted by Bronn, 'Ge.schichte der ""* ' Gardener's ("Chronicle,' 1865, p.

Natur,' B. ii. s. 77. On the effects of
the removal of the anthers, see ]\Ir.
Leitner, in Sillimau's ' iS'orth Ameri-

626; 1866, pp.290, 730; ^ad Verlot,
' Des Varietes,' p. 75.

152

STERILITY FROM THE DEVELOPMENT Chap. XVIIL

the antagonistic state, commonly arises from a pletlioric condition.
On the other hand, extremely poor soil sometimes, though rarely,
appears to cause doubleness : I formerly described ^*^^ some completely
double, bud-like, flowers produced in large numbers by stunted
wild plants of Oentiana amarella growing on a poor chalky bank. I
have also noticed a distinct tendency to doubleness in the flowers of
a Eanunculus, Horse-chestnut, and Bladder-nut {Ranunculus repens,
yEscuJus pavia, and Staphylea), growing under very unfavourable
conditions. Professor Lehmann ^^'^ found several wild plants growing
near a hot spring with double flowers. With respect to the cause of
doubleness, which arises, as we see, under widely different circum-
stances, I shall presently attempt to show that the most probable
view is that unnatural conditions first give a tendency to sterility,
and that then, on the principle of compensation, as the reproductive
organs do not j)erfoi'm their proper functions, they either become
developed into petals, or additional petals are formed. This
view has lately been supported by Mr. Laxton,^*^^ who advances the
ease of some common peas, which, after long-continued heavy rain,
flowered a second time, and produced double flowers.

Seedless Fruit. — Many of our most valuable fruits, although con-
sisting in a homological sense of widely different organs, are either
quite sterile, or produce extremely few seeds. This is notoriously
the case with our best pears, grapes, and figs, with the joine-apple,
banana, bread-fruit, pomegranate, azarole, date-palms, and some
members of the orange-tribe. Poorer varieties of these same fruits
either habitually or occasionally yield seed.^''^ Most horticulturists
look at the great size and anomalous development of the fruit as the
cause, and sterility as the result ; but the opj)osite view, as we shall
presently see, is more probable.

Sterility from the excessive development of the organs of Growth or
Vegetation. — Plants which from any cause grow too luxuriantly, and
produce leaves, stems, runners, suckers, tubers, bulbs, &c., in excess,
sometimes do not flower, or if they flower do not yield seed. To
make European vegetables under the hot climate of India yield
seed, it is necessary to check their growth ; and, when one-third
grown, they are taken up, and their stems and tap-roots are cut or

»«> ' Gardener's Chronicle,' 184-3, p.
628. In this article I sufirgested the
theory above given on the doubleness
of flowers. This view is adopted by
Carriere, ' Production et Fix. des
Var idles,' 1865, p. 67.

^"2 Quoted by Gartner, ' Bastarder-
zeugung,' s. 567.

»»2 'Gardener's Chronicle,' 18G6, p.
1)01.

»»* Lindley, 'Theory of Horticul-
ture,' pp. 175-179 ; Godron, ' De I'Es-
p6ce,' torn. ii. p. 106 ; Pickering,

* Races of Man ; ' Gallesio, ' Teoria
dellaRiproduzione,'1816, pp. 101-1 10.
Meyen (' Reise um Erde,' Th. ii. s.
214) states that at Manilla one
variety of the banana is full of seeds:
and Chamisso (Hooker's ' Bot. Misc.,'
vol. i. p. 310) describes a variety of
the bread-fruit in the jMariana Islands
with small fruit, containing seeds
which are frequently perfect. Burner,
in his ' Travels in Bokhara,' remarks
on the pomegranate seeding in Mazen*
deran, as a remarkable peculiarity.

Chap. XVIII. OF THE OKGANS OF VEGETATION.

153

mutilated. ^''^ So it is with hybrids; for instance, Prof. Lecoq^"'' had
three plants of Mirabilis, which, though they grew luxuriantly and
flowered, were quite sterile ; but after beating one with a stick until
a few branches alone were left, these at once yielded good seed. The
sugar-cane, which grows yigorously and produces a large supply of
succulent stems, never, according to various observers, bears seed in
the West Indies, Malaga, India, Cochin China, Mauritius, or the
Malay Archipelago.^*^^ Plants which produce a large number of
tubers are apt to be sterile, as occurs, to a certain extent, with the
common potato ; and Mr. Fortune informs me that the sweet
potato {ConvoJvuhis batatas) in China never, as far as he has seen,
yields seed. Dr. Eoyle remarks ^^^ that in India the A(;ave vivipara,
when grown in rich soil, invariably produces bulbs, but no seeds ;
whilst a poor soil and dry climate lead to an opposite result. In
China, according to Mr. Fortune, an extraordinary number of little
bulbs are developed in the axils of the leaves of the yam, and this
plant does not bear seed. Whether in these cases, as in those of
double flowers and seedless fruit, sexual sterility from changed
conditions of life is the primary cause which leads to the excessive
development of the organs of vegetation, is doubtful ; though some
evidence might be advanced in favour of this view. It is perhaps a
more probable view that plants which propagate themselves largely
by one method, namely by buds, have not sufficient vital power or
organised matter for the other method of sexual generation.

Several distinguished botanists and good practical judges believe
that long-continued propagation by cuttings, runners, tubers, bulbs,
&c., independently of any excessive development of these parts, is
the cause of many plants failing to produce flowers, or producing
only barren flowers, — it is as if they had lost the habit of sexual
generation.^^^ That many plants when thus propagated are sterile '
tliere can be no doubt, but as to whether the long continuance of this
form of propagation is the actual cause of their sterility, I will not
venture, from the want of sufficient evidence, to express an opinion.

That plants may be propagated for long periods by buds, without
the aid of sexual generation, we may safely infer from this being the
case with many plants which must have long survived in a state of
nature. As I have had occasion before to allude to this subject, I
will here give such cases as I have collected. Many alpine plants

^"^ Inglerlew, in ' Transact, of Agri-
cult, and Hort. Soc. of India,' vol. ii.

los 'De la Fecondation,' 1862, p.
308.

•07 Hooker's ' Bot. Misc.,' vol. i. p.
99; Gallesio, 'Teoria della Ripro-
duzione,' p. 110. Dr. J. de Cordemoy,
in 'Transact, of the R. Soc. of Mauri-
tius' (new serie.s), vol. vi. 1873, pp.
60-67, gives a large number of cases
of plants which never seed, including

several species indigenous in Mauri-
tius.

108 'Transact. Linn. Soc.,' vol. xvii.
p. 563.

'09 Godron, < De I'Esp&ce,' torn. ii.
p. 106 ; Herbert on Crocus, in ' Jour-
nal of Hort. Soc.,' vol. i., 184:6, p.
254 : Dr. Wight, from what he has
seen in India, believes in this view ;
* Madras Journal of Lit. and Science/
vol. iv., 1836, p. 61.

154

STERILITY.

Chap. XVIII

ascend mountains beyond the height at which they can produce
seed.^^° Certain species of Poa and Festuca, when growing on
mountain-pastures, propagate themselves, as I hear from Mr.
Bentham, almost exclusively by bulblets. Kalm gives a more curious
instance ^^^ of several American trees, which grow so plentifully in
marshes or in thick woods, that they are certainly well adapted for
these stations, yet scarcely ever produce seeds ; but when acciden-
tally growing on the outside of the marsh or wood, are loaded with
seed. The common ivy is found in Northern Sweden and Eussia,
but flowers and fruits only in the southern provinces. The Acorus
calamus extends over a large portion of the globe, but so rarely
perfects fruit that this has been seen only by a few botanists,
according to Caspary, all its pollen-grains are in a worthless condi-
tion."^ The Hypericum caJycinum, which propagates itself so freely
in our shrubberies by rhizomes, and is naturalised in Ireland,
blossoms profusely, but rarely sets any seed, and this only during
certain years; nor did it set any when fertilised in my garden by
pollen from plants growing at a distance, Tiie Ly^imachia riummu-
lai'iriy which is furnished with long runners, so seldom produces
seed-capsules, that Prof. Decaisne,"^ who has especially attended to
this plant, has never seen it in fruit. The Carex rigida often fails
\o perfect its seed in Scotland, Lapland, Greenland, Germany, and
New Hampshire in the United States."* The periwinkle ( I'inca
irunor), which spreads largely by runners, is said scarcely ever to
produce fruit in England ; "^ but this plant requires insect-aid for
its fertilisation, and the proper insects may be absent or rare. The
Jusst'oea graridiflora. has become naturalised in Southern France, and
has spread by its rhizomes so extensively as to impede the naviga-
tion of the waters, but never produces fertile seed,"^ The horse-
radish {Cochlearia armoracia) spreads pertinaciously and is natural-
ised in various parts of Europe ; though it bears flowers, these
rarely produce capsules : Professor Caspary informs me that he has
watched this plant since 1851, but has never seen its fruit; 65 per
cent, of its pollen-grains are bad. The common llanunculus ficaria
rarely bears seed in England, France, or Switzerland ; but in 1863
I. observed seeds on several plants growing near my house."" Other

^'" Wahlenberg specifies eight
species in this state on the Lapland
Alps : see Appendix to Linnaeus' ' Tour
in Lapland,' translated by Sir J. E.
Smith, vol. ii. pp. 274-280.

''' 'Travels in North America,'
Eng. translat., vol. iii. p. 175.

^'2 With respect to the ivy and
Acorus, see Dr. Bromfield in the ' Phy-
tologist,' vol. iii. p. 376. Also Lind-
lev and Vaucher on the Acorus, and
see Caspary as below.

^" 'Annal. des Sc. Nat.,' 3rd series,

ZooL, torn. iv. p. 280. Prof. Decaisne
refers also to analogous cases with
mosses and lichens near Paris.

"•• Mr. Tuckermaun, in Silliman's
'American Journal of Science,' vol.
xlv. p. 1.

>i^ Sir J. E. Smith, ' English Flora,'
vol. 1. p. 339.

"« G. Planchon, 'Flora de Mont-
pellier,' 1864, p. 20.

^^' On the non-production of seeds
in England, see Mr. Crocker, in ' Gar-
dener's Weekly Magazine,' 1852, p.

Chap. XVIU.

STERILITY.

155

rases analogous with the foregoing conld be given; for instance,
some kinds of mosses and lichens have never been seen to fructify in
France.

Some of these endemic and naturalised plants are probably
rendered sterile from excessive multiplication by buds, and their
consequent incapacity to produce and nourish seed. But the
sterility of others more probably depends on the peculiar condi-
tions under which they live, as in the case of the ivy in the northern
parts of Europe, and of the trees in the swamps of the United
States ; yet these plants must be in some respects eminently well
adapted for the stations which they occupy, for they hold their
places against a host of competitors.

Finally, the high degree of sterility which often accom-
panies the doubling of flowers, or an excessive develoj)ment of
fruit, seldom siij)ervenes at once. An incipient tendency is
observed, and continued selection completes the result. The
view which seems the most probable, and which connects
together all the foregoing facts and brings them within our
present subject, is, that changed and unnatural conditions of
life first give a tendency to sterility; and in consequence of
this, the organs of reproduction being no longer able fully to
perform their proper functions, a supply of organised matter,
not required for the development of the seed, flows either into
these organs and renders them foliaceous, or into the fruit,
stems, tubers, &c., increasing their size and succulency. But
it is probable that there exists, independently of any incipient
sterility, an antagonism between the two forms of repro-
duction, namely, by seed and buds, when either is carried to
an extreme degree. That incipient sterility plays an impor-
tant part in the doubling of flowers, and in the other cases
just specified, I infer chiefly from the following facts. When
fertility is lost from a wholly different cause, namely, from
hybridism, there is a strong tendency, as Giirtner^^"^ affirms,

70 ; Vaucher, ' Hist. Pliys. Plantes
d'Euroj^e,' torn. i. p. 33 ; Lecoq, ' Geo-
graph. Bot. d'Europe,' torn. iv. p.
46(3; Dr. D. Clos, in 'Annal. des Sc.
Nat.,' 3rd series, Bot., torn, xvii.,
1852, p. 129: this latter author refers
to other analogous cases. See more
especially on this plant, and on other
allied cases, Prof. Caspary, " Die Nu-

phav,"' ibhand. Naturw.Gesellsch. zu
Halle,' B. xi. 1870, p. 40, 78.

"* ' Bastarderzeugung,' s. 5G5
Kolreuter (Dritte Fortsetzung, s.
73, 87, 119) also shows that wher.
two species, one single and the other
double, are crossed, the hybrids are
apt to be extremely double.

156 STERILITY. CuAP. XVIII.

for flowers to become double, and this tendency is inherited.
Moreover, it is notorious that with hybrids the male organs
become sterile before the female organs, and with double
flowers the stamens first become foliaceous. This latter fact
is well shown by the male flowers of dioecious plants, which,
according to Gallesio,^^^ first become double. Again, Gart-
ner ^^° often insists that the flowers of even utterly sterile
hybrids, which do not produce any seed, generally yield
perfect capsules or fruit,- a fact which has likewise been
repeatedly observed by Naudin with the Cucurbitace<e ; so
that the production of fruit by plants rendered sterile through
iny cause is intelligible. Kolreuter has also expressed his
unbounded astonishment at the size and development of the
tubers in certain hybrids; and all experimentalists^^^ have
remarked on the strong tendency in hybrids to increase by
roots, runners, and suckers. Seeing that hybrid plants,
which from their nature are more or less sterile, thus tend to
produce double flowers ; that the}^ have the parts including
the seed, that is the fruit, perfectly developed, even when
containing no seed ; that they sometimes yield gigantic
roots ; that they almost invariably tend to increase largely by
suckers and other such means ; — seeing this, and knowing,
from the many facts given in the earlier parts of this chapter,
that almost all organic beings when exposed to unnatural
conditions tend to become more or less sterile, it seems much
the most probable view that with cultivated plants sterility
is the exciting cause, and double flowers, rich seedless fruit,
and in some cases largely-developed organs of vegetation, &c.,
are the indirect results — these results having been in most
cases largely increased through continued selection by man.

*^' 'Teoria della Riproduzione ^^^ ' Bastarderzeugung,' s. 573.

V eg.,' 1816, p. 73. »" Ibid., s. 527.

f

Uhap. XIX. SUMMARY OF THE FOUR LAST CHAPTERS. 157

CHAPTER XIX.

SUMMARY OF THE FOUR LAST CHAPTERS, WITH REMARKS ON

HYBRIDISM.

ON THE EFFECTS OF CROSSING — THE INFLUENCE OF DOMESTICATION ON
FERTILITY — CLOSE INTERBREEDING — GOOD AND EVIL RESULTS FROM
CHANGED CONDITIONS OP LIFE — VARIETIES WHEN CROSSED NOT IN-
VARIABLY FERTILE ON THE DIFFERENCE IN FERTILITY BETWEEN

CROSSED SPECIES AND VARIETIES — CONCLUSIONS WITH RESPECT TO
HYBRIDISM — LIGHT THROWN ON HYBRIDISM BY THE ILLEGITIMATE
PROGENY OF HETEROSTYLED PLANTS — STERILITY OF CROSSED SPECIES
DUE TO DIFFERENCES CONFINED TO THE REPRODUCTIVE SYSTEM — NOT
ACCUMULATED THROUGH NATURAL SELECTION — REASONS WHY DOMESTIC
VARIETIES ARE NOT MUTUALLY STERILE — TOO MUCH STRESS HAS BEEN
LAID ON THE DIFFERENCE IN FERTILITY BETWEEN CROSSED SPECIES AND
CROSSED VARIETIES — CONCLUSION.

It w^as shown in the fifteenth chapter that v^^hen individuals
of the same variety, or even of a distinct variety, are allowed
freely to intercross, uniformity of character is ultimately ac-
quired. Some few characters, however, are incapable of
fusion, but these are unimportant, as they are often of a
semi-monstrous nature, and have suddenly apj)eared. Hence,
to preserve our domesticated breeds true, or to improve them
by methodical selection, it is obviously necessary that they
should be kept separate. Nevertheless, a whole body of
individuals may be slowly modified, through unconscious
selection, as we shall see in a future chapter, without separa-
ting them into distinct lots. Domestic races have often been
intentionally modified by one or two crosses, made with some
allied race, and occasionally even by repeated crosses with
very distinct races ; but in almost all such cases, long-con-
tinued and careful selection has been absolutely necessary,
owing to the excessive variability of the crossed offspring,
due to the principle of reversion. In a few instances, how-
ever, monofrels have retained a uniform character from their
first production.

When two varieties are allowed to cross freely, and one is

29

158 SUMMARY OF THE Chap. XIX.

much, more mimerous than the other, the former will ulti-
mately absorb the latter. Should both varieties exist in
nearly equal numbers, it is probable that a considerable
period would elapse before the acquirement of a uniform
character; and the character ultimately acquired would
largely depend on prepotency of transmission and on the con-
ditions of life; for the nature of these conditions would
generally favour one variety more than another, so that a kind
of natural selection would come into play. Unless the crossed
offspring were slaughtered by man without the least discri
mination, some degree of unmethodical selection would like-
wise come into action. From these several considerations
we may infer, that when two or more closely allied species
first came into the po.^session of the same tribe, their crossing
wdl not have influenced, in so great a degree as has often
been supposed, the character of the offspring in future times ;
although in some cases it probably has had a considerable
effect.

Domestication, as a general rule, increases the prolificness
of animals and plants. It eliminates the tendency to sterility
wliich is common to species when first taken from a state of
nature and crossed. On this latter head we have no direct
evidence ; but as our races of dogs, cattle, pigs, &c., are almost
certainly descended from aboriginally distinct stocks, and as
these races are now fully fertile together, or at least incom-
pMrably more fertile than most species when crossed, we may
with entire confidence accept this conclusion.

Abundant evidence has been given that crossing adds to
the size, vigour, and fertility of the offspring. This holds
good when there has been no previous close interbreeding.
It applies to the individuals of the same variety but belonging
to different families, to distinct varieties, sub-species, and
even to species. In the latter case, though size is gained,
fertility is lost ; but the increased size, vigour, and hardiness
of many hybrids cannot be accounted for solely on the
principle of compensation from the inaction of the reproduc-
tive system. Certain plants whilst growing under their
natural conditions, others when cultivated, and others of
hybrid origin, are completely self-impotent, though per-

Chap. XIX. FOUR LAST CHAPTERS. 159

fectly healtliy ; and sucli plants can be stimulated to fertility
only by being crossed with other individuals of the same or
of a distinct species.

On the other hand, long-continued close interbreeding
between the nearest relations diminishes the constitutional
vigour, size, and fertility of the offspring ; and occasionally
leads to malformations, but not necessarily to general de-
terioration of form or structure. This failure of fertility
shows that the evil results of interbreeding are independent
of the augmentation of morbid tendencies common to both
parents, though this augmentation no doubt is often highly
injurious. Our belief that evil follows from close interbreed-
ing rests to a certain extent on the experience of practical
breeders, especially of those who have reared many animals
of quickl}^ propagating kinds ; but it likewise rests on several
carefully recorded experiments. With some animals close
interbreeding may be carried on for a long period with im-
punity by the selection of the most vigorous and healthy
individuals ; but sooner or later evil follows. The evil, how-
ever, comes on so slowly and gradually that it easily escapes
observation, but can be recognised by the almost instantaneous
manner in which size, constitutional vigour, and fertility are
regained when animals that have long been interbred are
crossed with a distinct family.

These two great classes of facts, namely, the good derived
from crossing, and the evil from close interbreeding, with the
consideration of the innumerable adaptations throughout
nature for compelling, or favouring, or at least permitting,
the occasional union of distinct individuals, taken together,
lead to the conclusion that it is a law of nature that organic
beings shall not fertilise themselves for perpetuity. This law
was first plainly hinted at in 1799, with respect to plants,
by Andrew Knight,^ and, not long afterwards, that sagacious

^ ' Transactions Phil. Soc.,' 1799, observei* failftd to understand the full
p. 202. For Kolreuter, see ' Mem. de meaning of the structure of the
I'Acad. de St.-Petersbourg,' torn. iii. flowers which he has so well de-
1809 (published 1811), p. 197. In scribed, from not always having
reading C. K. Sprengel's remarkable before his mind the key to the pro-
work, 'Das entdeckte Geheimniss,' blem, namely, the good derived from
&c., 1793, it is curious to observe the crossing of distinct individual
how often this wonderfully acute plants.

160 SUMMABY OF THE Chap. XIX.

observer Kolreiiter, after showing how well the Malvaceae
are adapted for crossing, asks, "an id aliquid in recessu
habeat, quod hujuscemodi flores nunquam proprio suo pul-
vere, sed semper eo aliarum suse speciei impregnentur, nierito
quaeritur ? Certe natura nil facit frnstra." Although we
may demur to Kolreuter's saying that nature does nothing
in vain, seeing how many rudimentary and useless organs
there are, yet undoubtedly the argument from the innumer-
able contrivances, which favour crossing, is of the greatest
weight. The most important result of this law is that it
leads to uniformity of character in the individuals of the
same species. In the case of certain hermaphrodites, which
probably intercross only at long intervals of time, and with
unisexual animals inhabiting somewhat separated localities,
which can only occasionally come into contact and pair, the
greater vigour and fertility of the crossed offspring will
ultimately tend to give uniformity of character. But when
we go beyond the limits of the same species, free intercrossing
is barred by the law of sterility.

In searching for facts which might throw light on the
cause of the good effects from crossing, and of the evil effects
from close interbreeding, we have seen that, on the one hand,
it is a widely prevalent and ancient belief, that animals and
plants profit from slight changes in their condition of life ;
and it would appear that the germ, in a somewhat analogous
manner, is more effectually stimulated by the male element,
when taken from a distinct individual, and therefore slightly
modified in nature, than when taken from a male having the
same identical constitution. On the other hand, numerous
facts have been given, showing that when animals are first
subjected to captivity, even in their native land, and although
allowed much liberty, their reproductive functions are often
greatly impaired or quite annulled. Some groups of animals
are more affected than others, but with apparently capricious
exceptions in every group. Some animals never or rarely
couple under confinement ; some couple freely, but never or
rarely conceive. The secondary male characters, the maternal
functions and instincts, are occasionally affected. With
plants, when first subjected to cultivation, analogous facts

Chap. XIX. FOUR LAST CHAPTERS. 161

have been observed. We probably owe our double flowers,
rich seedless fruits, and in some cases greatly developed
tubers, &c., to incipient sterility of the above nature combined
with a copious siipply of nutriment. Animals which have
long been domesticated, and plants which have long been
cultivated, can generally withstand, with unimpaired fertility,
great changes in their conditions of life ; though both are
sometimes slightly affected. With animals the somewhat
rare capacity of breeding freely under confinement, together
with their utility, mainly determine the kinds which have
been domesticated.

We can in no case precisely say what is the cause of the
diminished fertility of an animal when first captured, or of a
plant when first cultivated ; we can only infer that it is caused
by a change of some kind in the natural conditions of life.
The remarkable susceptibility of the reproductive system to
such changes, — a susceptibility not common to any other
organ, — apparently has an important bearing on Variability,
as we shall see in a future chapter.

It is impossible not to be struck with the double parallelism
between the two classes of facts just alluded to. On the one
hand, slight changes in the conditions of life, and crosses
between slightly modified forms or varieties, are beneficial as
far as prolificness and constitutional vigour are concerned.
On the other hand, changes in the conditions greater in degree,
or of a different nature, and crosses between forms which
have been slowly and greatly modified by natural means, —
in other words, between species, — are highly injurious, as far
as the reproductive system is concerned, and in some few
instances as far as constitutional vigour is concerned. Can
this parallelism be accidental ? Does it not rather indicate
some real bond of connection ? As a fire goes out unless
it be stirred up, so the vital forces are always tending,
according to Mr. Herbert Spencer, to a state of equilibrium,
unless disturbed and renovated through the action of other
forces.

In some few cases varieties tend to keep distinct, by breed-
ing at different seasons, by great difference in size, or by
sexual preference. But the crossing of varieties, far from

162 HYBRIDISM. CuAP. XIX.

diminishing, generally adds to tlie fertility of tlie first
union and of the mongrel offspring. Whether all the more
widely distinct domestic varieties are invariably quite fertile
when crossed, we do not positively know ; much time and
trouble would be requisite for the necessary experiments, and
many difficulties occur, such as the descent of the various
races from aboriginally distinct species, and the doubts
whether certain forms ought to be ranked as species or
varieties. Nevertheless, the wide experience of practical
breeders proves that the great majority of varieties, even if
some should hereafter prove not to be indefinitely fertile
inter se, are far more fertile when crossed, than the vast
majority of closely allied natural species. A few remarkable
cases have, however, been given on the authority of excellent
observers, showing that with plants certain forms, which un-
doubtedly must be ranked as varieties, yield fewer seeds when
crossed than is natural to the parent-species. Other varieties
have had their reproductive powers so far modified that they
are either more or less fertile than their parents, when crossed
with a distinct species.

Kevertheless, the fact remains indisputable that domesti-
cated varieties, of animals and of plants, which differ greatly
from one another in structure, but which are certainly
descended from the same aboriginal species, such as the races
of the fowl, pigeon, many vegetables, and a host of other
productions, are extremely fertile when crossed ; and this
seems to make a broad and impassable barrier between
domestic varieties and natural species. But, as I will now
attempt to show, the distinction is not so great and over-
whelmingly important as it at first aji^^ears.

On the Difference in Fertility between Varieties and Species wJien

crossed.

This work is not the proper place for fully treating the
subject of hybridism, and I have already given in my 'Origin
of Species ' a moderately full abstract. I will here merely
enumerate the general conclusions w^hich may be relied on,
and which bear on our present point.

Firstly, the laws governing the production of hybrids are

Chap. XIX. HYBRIDISM. 163

identical, or nearly identical, in tlie animal and vegetable
kingdoms.

Secondly, the sterility of distinct species when first united,
and that of their h^'brid offspring, graduate, by an almost
infinite number of steps, from zero, when the ovule is never
impregnated and a seed-capsule is never formed, up to com-
plete fertility. We can only escape the conclusion that some
species are fully fertile when crossed, by determining to
designate as varieties all the forms which are quite fertile.
This high degree of fertility is, however, rare. Nevertheless,
plants, which have been exposed to unnatural conditions,
sometimes become modified in so peculiar a manner, that they
are much more fertile when crossed with a distinct species than
when fertilised by their own pollen. Success in effecting a
first union between two species, and the fertility of their
hybrids, depend in an eminent degree on the conditions of
life being favourable. The innate sterility of hybrids of the
same parentage and raised from the same seed-capsule often
differs much in degree.

Thirdly, the degree of sterility of a first cross between two
species does not always run strictly parallel with that of their
hybrid offspring. Many cases are known of species which
can be crossed with ease, but yield hybrids excessively
sterile; and conversely some which can be crossed with
great difficulty, but produce fairly fertile hybrids. This is
an inexplicable fact, on the view that species have been
specially endowed with mutual sterility in order to keep
them distinct.

Fourthly, the degree of sterility often differs greatly in two
species when reciprocally crossed ; for the first will readily
fertilise the second ; but the latter is incapable, after hundreds
of trials, of fertilising the former. H3^brids produced from
reciprocal crosses between the same two species likewise
sometimes differ in their degree of sterility. These cases
also are utterly inexplicable on the view of sterility being a
special endowment.

Fifthly, the degree of sterility of first crosses and of hybrids
runs, to a certain extent, parallel with the general or system-
atic affinity of the forms which are united. For species be-

164 HYBRIDISM. Chap. XIX

longing to distinct genera can rarely, and ttiose belonging
to distinct families can never, be crossed. The parallelism,
however, is far from complete ; for a multitude of closely
allied species will not unite, or unite vrith extreme difficulty,
whilst other species, widely different from one another, can
be crossed with perfect facility. Nor does the difficulty
depend on ordinary constitutional differences, for annual and
perennial plants, deciduous and evergreen trees, plants
flowering at different seasons, inhabiting different stations,
and naturally living under the most opposite climates, can
often be crossed with ease. The difficulty or facility ap-
parently depends exclusively on the sexual constitution of
the species which are crossed ; or on their sexual elective
affinity, i.e. Walilverwandtschaft of Gartner. As species rarely
or never become modified in one character, without being at
the same time modified in many characters, and as systematic
affinity includes all visible similarities and dissimilarities,
any difference in sexual constitution between two species
would naturally stand in more or less close relation with their
systematic position.

Sixthly, the sterility of species when first crossed, and that
of hybrids, may possibly depend to a certain extent on distinct
causes. With pure species the reproductive organs are in a
perfect condition, whilst with hybrids they are often plainly
deteriorated. A hybrid embryo which partakes of the con-
stitution of its father and mother is exposed to unnatural
conditions, as long as it is nourished within the womb, or
egg, or seed of the mother-form ; and as we know that
unnatural conditions often induce sterility, the reproductive
organs of the hybrid might at this early age be permanently
affected. But this cause has no bearing on the infertility of
first unions. The diminished number of the offspring from
first unions may often result, as is certainly sometimes the
case, from the premature death of most of the hybrid embryos.
But we shall immediately see that a law of an unknown
nature apparently exists, which leads to the offspring from
unions, which are infertile, being themselves more or less
infertile ; and this at present is all that can be said.

Seventhly, hybrids and mongrels present, with the one great

Chap. XIX. HYBRIDISM. 165

excej)tion of fertility, the most striking accordance in all other
respects ; namely, in the laws of their resemblance to their
two parents, in their tendency to reversion, in their varia-
bility, and in being absorbed through repeated crosses by
either parent- form.

After arriving at these conclusions, T was led to investigate
a subject which throws considerable light on hybridism,
namely, the fertility of heterostyled or dimorphic and
triinorphic plants, when illegitimately united. I have had
occasion several times to allude to these plants, and I may
here give a brief abstract of my observations. Several plants
belonging to distinct orders present two forms, which exist
in about equal numbers, and which differ in no respect except
in their reproductive organs ; one form having a long pistil
with short stamens, the other a short pistil with long
stamens ; both with differently sized pollen-grains. With
trimorphic plants there are three forms likewise differing in
the lengths of their pistils and stamens, in the size and colour
of the pollen-grains, and in some other respects ; and as in
each of the three forms there are two sets of stamens, there
are altogether six sets of stamens and three kinds of pistils.
These organs are so proportioned in length to one another
that, in any two of the forms, half the stamens in each stand
on a level with the stigma of the third form. Kow I have
shown, and the result has been confirmed by other observers,
that, in order to obtain full fertility with these plants, it is
necessary that the stigma of the one form should be fertilised
by pollen taken from the stamens of corresponding height in
the other form. So that with dimorphic species two unions,
which may be called legitimate, are fully fertile, and two,
which may be called illegitimate, are more or less infertile.
With trimorphic species six unions are legitimate, or fully
fertile, and twelve are illegitimate, or more or less infertile.^

The infertility which may be observed in various dimorphic

* My observations 'On the Cha- Linnean Soc.,' vol. x. p. 393. The

racter and hybrid-like nature of the abstract here given is nearly the

offspring from the illegitimate union same with that which appeared in

of Dimorphic and Trimorphic Plants ' the 6th edition of my ' Origin of

urere published in the ' Journal of the Species.*

166 HYBRIDISM. Chap. XIX.

and trimorpliic plants, when illegitimately fertilised, that is,
b}^ pollen taken from stamens not corresponding in height
with the pistil, differs mnch in degree, np to absolute and
utter sterility ; just in the same manner as occurs in crossing
distinct species. As the degree of sterility in the latter case
depends in an eminent degree on the conditions of life being
more or less favourable, so I have found it with illegitimate
unions. It is well known that if pollen of a distinct species
be placed on the stigma of a flower, and its own pollen be
afterwards, even after a considerable interval of time, placed
on the same stigma, its action is so strongly prej)otent that it
generally annihilates the effect of the foreign pollen ; so it is
with the pollen of the several forms of the same species, for
legitimate pollen is strongly prepotent over illegitimate
pollen, when both are placed on the same stigma. I ascer-
tained this by fertilising several flowers, first illegitimately,
and twenty-four hours afterwards legitimately, with pollen
taken from a peculiarly coloured variety, and all the seedlings
were similarly coloured ; this shows that the legitimate
pollen, though applied twenty-four hours subsequently, had
wholly destroyed or prevented the action of the previously
applied illegitimate pollen. Again, as, in making reciprocal
crosses between the same two species, there is occasionally a
great difference in the result, so the same thing occurs with
trimorphic plants ; for instance, the mid-sty ltd form of
Lythrum salicaria could be illegitimately fertilised with the
greatest ease by pollen from the longer stamens of the short-
styled form, and yielded many seeds ; but the short-styled form
did not yield a single seed when fertilised by the longer
stamens of the mid-styled form.

In all these respects the forms of the same undoubted
species, when illegitimately united, behave in exactly the
same manner as do two distinct species when crossed. This
led me carefully to observe during four years many seedlings,
raised from several illegitimate unions. 1'he chief result is
that these illegitimate plants, as they may be called, are not
fully fertile. It is possible to raise from dimorphic species,
both long-styled and short-stj^led illegitimate plants, and
from trimorphic plants all three illegitimate forms. These

Chap. XIX. HYBRIDISM. 167

can then be properly united in a legitimate manner. When
this is done, there is no apparent reason why they should
not jdeld as many seeds as did their parents when legiti-
mately fertilised. But such is not the case ; they are all
infertile, but in various degrees ; some being so utterly and
incurably sterile that they did not yield during four seasons
a single seed or even seed-capsule. These illegitimate plants,
which are so sterile, although united with each other in a
legitimate manner, may be strictly compared with hybrids
w^hen crossed inter se, and it is well known how sterile these
latter generally are. When, on the other hand, a hybrid is
crossed Tvdth either pure parent-species, the sterility is usually
much lessened : and so it is when an illegitimate plant is
fertilised by a legitimate plant. In the same manner as the
sterility of hybrids does not always run parallel with the
difficulty of making the first cross between the two parent-
species, so the sterility of certain illegitimate plants was
unusually great, whilst the sterility of the union from which
they were derived was by no means great. With hybrids
raised from the same seed-capsule the degree of sterility is
innately variable, so it is in a marked manner with illegiti-
mate plants. Lastly, many hybrids are profuse and persistent
flowerers, whilst other and more sterile hybrids produce few
flowers, and are weak, miserable dwarfs ; exactly similar
cases occur with the illegitimate offspring of various dimorphic
and trimorphic plants.

Although there is the closest identity in character and
behaviour between illegitimate plants and hybrids, it is
hardly an exaggeration to maintain that the former are
hybrids, but produced within the limits of the same sjDecies
by the improper union of certain forms, whilst ordinary
hybrids are produced from an improper union between so-
called distinct species. We have alread}^ seen that there is
the closest similarity in all respects between first illegitimate
unions, and first crosses between distinct species. This will
perhaps be made more fully apparent by an illustration : we
may suppose that a botanist found two well-marked varieties
(and such occur) of the long-styled form of the trimorphic
Ly thrum salicaria, and that he determined to try by crossing

168 HYBRIDISM. Chap. XIX.

whether they were specifically distinct. He would find that
they yielded i)nly about one-fifth of the proper number of
seed, and that they behaved in all the other above- specified
respects as if they had been two distinct species. But to
make the case sure, he would raise plants from his supposed
hj'bridised seed, and he would find that the seedlings were
miserably dwarfed and utterly sterile, and that they behaved
in all other respects like ordinary hybrids. He might then
maintain that he had actually proved, in accordance with the
common view, that his two varieties were as good and as
distinct species as any in the world ; but he would be com-
pletely mistaken.

The facts now given on dimorphic and trimorphic plants
are important, because they show us, first, that the physio-
logical test of lessened fertility, both in first crosses and in
hybrids, is no criterion of specific distinction ; secondly,
because we may conclude that there is some unknown bond
which connects the infertility of illegitimate unions with'that
of their illegitimate offspring, and we are led to extend the
same view to first crosses and hybrids ; thirdly, because we
find, and this seems to me of especial importance, that two or
three forms of the same species may exist and may difier in no
respect whatever, either in structure or in constitution,
relatively to external conditions, and yet be sterile when
united in certain ways. For we must remember that it is
the union of the sexual elements of individuals of the same
form, for instance, of two long-styled forms, which results in
sterility ; whilst it is the union of the sexual element proper
to two distinct forms which is fertile. Hence the case appears
at first sight exactly the reverse of what occurs in the
ordinary unions of the individuals of the same species, and
with crosses between distinct species. It is, however, doubt-
ful whether this is really so ; but I will not enlarge on this
obscure subject.

We may, however, infer as probable from the consideration
of dimorphic and trimorphic plants, that the sterility of dis-
tinct species when crossed, and of their hybrid progeny,
depends exclusively on the nature of their sexual elements,
and not ou any difference in their structure or general con-

Chap. XIX. HYBRIDISM. 169

btitution. We are also led to this same conclusion by con-
sidering reciprocal crosses, in which the male of one species
cannot be united, or only with great difficulty, with the
female of a second species, whilst the converse cross can be
effected with perfect facility. That excellent observer, Gartner,
likewise concluded that species when crossed are sterile owing
to differences confined to their reproductive systems.

On the principle which makes it necessary for man, whilst
he is selecting and improving his domestic varieties, to keep
them separate, it would clearly be advantageous to varieties
in a state of nature, that is to incipient species, if they could
be kept from blending, either through sexual aversion, or by
becoming mutually sterile. Hence it at one time appeared to
me probable, as it has to others, that this sterility might have
been acquired through natural selection. On this view we
must suppose that a shade of lessened fertility first spon-
taneously appeared, like any other modification, in certain
individuals of a species when crossed with other individuals
of the same species; and that successive slight degrees of
infertility, from being advantageous, were slowly accumulated.
This appears all the more probable, if Ave admit that the
structural difierences between the forms of dimorphic and
trimorphic plants, as the length and curvature of the pistil,
&c., have been co-adapted through natural selection ; for if
this be admitted, we can hardly avoid extending the same
conclusion to their mutual infertility. Sterility, moreover, has
been acquired through natural selection for other and widely
different purposes, as with neuter insects in reference to their
social economy. In the case of plants, the flowers on the
circumference of the truss in the guelder-rose (^Viburnum
opulus) and those on the summit of the spike in the feather-
hyacinth [3Iiiscari comosum) have been rendered conspicuous,
and apparently in consequence sterile, in order that insects
might easily discover and visit the perfect flowers. But
when we endeavour to apply the principle of natural selection
to the acquirement by distinct species of mutual sterility, we
meet with great difficulties. In the first place, it may be
remarked that separate regions are often inhabited by groups

170 HYBRIDISM. Chap. XIX.

of species or by single species, whicli wlien brought together
and crossed are found to be more or less sterile ; now it could
clearly have been no advantage to such separated species to
have been rendered mutually sterile, and consequently this
could not have been effected through natural selection ; but
it may perhaps be argued, that, if a species were rendered
sterile with some one compatriot, sterility with other species
Wwuld follow as a necessary consequence. In the second
place, it is as much opposed to the theory of natural selection,
as to the theory of special creation, that in reciprocal crosses
the male element of one form should have been rendered
utterly impotent on a second form, whilst at the same time
the male element of this second form is enabled freely to
fertilise the first form ; for this peculiar state of the repro-
ductive system could not possibly have been advantageous
to either species.

In considering the probability of natural selection having
come into action in rendering species mutually sterile, one
of the greatest difficulties will be found to lie in the existence
of many graduated steps from slightlj^ lessened fertility to
absolute sterility. It may be admitted, on the principle
above explained, that it would profit an incipient species if it
were rendered in some slight degree sterile when crossed with
its parent-form or with some other variety ; for thus fewer
bastardised and deteriorated offspring would be produced to
commingle their blood with the new species in process of
formation. But he who will take the trouble to reflect on the
steps by which this first degree of sterility could be increased
through natural selection to that higher degree which is
common to so many species, and which is universal with
species which have been differentiated to a generic or family
rank, will find the subject extraordinarily complex. After
mature reflection it seems to me that this could not have been
effected through natural selection. Take the case of any two
species which, when crossed, produce few and sterile offspring ;
now, what is there which could favour the survival of those
individuals which happened to be endowed in a slightly
higher degree with mutual infertility, and which thus
approached by one small step towards absolute sterility "^

Chap. XIX. HYBRIDISM. 171

Yet an advance of this kind, if the theory of natural selection
be brought to bear, must have incessantly occurred with
many species, for a multitude are mutually quite barren.
AYith sterile neuter insects we have reason to believe that
modifications in their structure and fertility have been slowly
accumulated by natural selection, from an advantage having
been thus indirectly given to the community to which they
belonged over other communities of the same species ; but an
individual animal not belonging to a social community, if
rendered slightly sterile when crossed with some other variety,
would not thus itself gain any advantage or indirectly give
any advantage to the other individuals of the same variety,
thus leading to their preservation.

But it would be superfluous to discuss this question in
detail ; for with plants we have conclusive evidence that the
sterility of crossed species must be due to some principle,
quite independent of natural selection. Both Gartner and
Kcilreuter have proved that in general including numerous
species, a series can be formed from species which when crossed
yield fewer and fewer seeds, to species which never produce a
single seed, but yet are affected by the pollen of certain other
species, for the germen swells. It is here manifestly im-
possible to select the more sterile individuals, which have
already ceased to yield seeds ; so that this acme of sterility,
when the germen alone is affected, cannot have been gained
through selection ; and from the laws governing the various
grades of sterility being so uniform throughout the animal
and vegetable kingdoms, we may infer that the cause, what-
ever it may be, is the same or nearly the same in all cases.

As species have not been rendered mutually infertile
through the accumulative action of natural selection, and as
we may safely conclude, from the previous as well as from
other and more general considerations, that they have not
been endowed through an act of creation with this quality,
we must infer that it has arisen incidentally during their slow
formation in connection with other and unknown changes in
their organisation. By a quality arising incidentally, I refer
to such cases as different species of animals and plants being
differently affected by poisons to which they are not naturally

172 HYBRIDISM. Chap. XIX.

exposed ; and this difference in susceptibility is clearly in-
cidental on other and unknown differences in their organisa-
tion. So again the capacity in different kinds of trees to be
grafted on each other, or on a third species, differs much, and
is of no advantage to these trees, but is incidental on struc-
tural or functional differences in their woody tissues. We
need not feel surprise at sterility incidentally resulting from
crosses between distinct species, — the modified descendants of
a common progenitor, — when we bear in mind how easily the
reproductive system is affected by various causes — often by
extremely slight changes in the conditions of life, by too close
interbreeding, and by other agencies. It is well to bear in
mind such cases as that of the Passiflora alata, which re-
covered its self-fertility from being grafted on a distinct
species — the cases of plants which normally or abnormally
are self-impotent, but can readily be fertilissed by the pollen
of a distinct species — and lastly the cases of individual
domesticated animals which evince towards each other sexual
incompatibility.

, We now at last come to the immediate point under dis-
cussion : how is it that, with some few exceptions in the case
of plants, domesticated varieties, such as those of the dog, fowl,
pigeon, several fruit-trees, and culinary vegetables, which differ
from each other in external characters more than many species,
are perfectly fertile when crossed, or even fertile in excess,
whilst closely allied species are almost invariably in some
degree sterile ? W^e can, to a certain extent, give a satisfac-
tory answer to this question. Passing over the fact that the
amount of external difference between two species is no sure
guide to their degree of mutual sterility, so that similar differ-
ences in the case of varieties would be no sure guide, we know
that with species the cause lies exclusively in differences in
their sexual constitution. Now the conditions to which
domesticated animals and cultivated plants have been sub-
jected have had so little tendency towards modifying the
reproductive system in a manner leading to mutual sterilit}^,
that we have very good grounds for admitting the directly
opposite doctrine of Pallas, namely, that such conditio is

Chap. XIX. HYBKIDISM. 173

generally eliminate this tendency ; so that the domesticated
descendants of species, which in their natural state would
have been in some degree sterile when crossed, become
perfectly fertile together. AVith plants, so far is cultivation
from giving a tendency towards mutual sterility, that in
several well - authenticated cases, already often alluded to,
certain species have been affected in a very different manner,
for they have become self-impotent, whilst still retaining the
capacity of fertilising, and being fertilised by, distinct species.
If the Pallasian doctrine of the elimination of sterility through
long-continued domestication be admitted, and it can hardly
be rejected, it becomes in the highest degree improbable that
similar circumstances should commonly both induce and
eliminate the same tendency ; though in certain cases, with
species having a peculiar constitution, sterility might occa-
sionally be thus induced. Thus, as I believe, we can under-
stand why with domesticated animals varieties have not been
produced which are mutually sterile ; and why with plants
only a few such cases have been observed, namely, by Gartner,
with certain varieties of maize and verbascum, by other ex-
perimentalists with varieties of the gourd and melon, and by
Kolreuter with one kind of tobacco.

With respect to varieties which have originated in a state
of nature, it is almost hopeless to expect to prove by direct
evidence that they have been rendered mutually sterile ; for if
even a trace of sterility could be detected, such varieties would
at once be raised by almost every naturalist to the rank of
distinct species. If, for instance, Gartner's statement were
fully confirmed, that the blue and red flowered forms of the
pimpernel (^AnagalUs arvensis) are sterile when crossed, I pre-
sume that all the botanists who now maintain on various
grounds that these two forms are merely fleeting varieties,
would at once admit that they were specifically distinct.

The real difficulty in our present subject is not, as it appears
to me, why domestic varieties have not become mutually in-
fertile when crossed, but why this has so generally occurred
with natural varieties as soon as they have been modified in a
sufficient and permanent degree to take rank as species. We
are far from precisely knowing the cause ; but we can see

174 HYBRIDISM. Chap. XIX.

that tlie species, owing to their struggle for existence with
numerous competitors, must have been exposed to more uni-
form conditions of life during long periods of time than
domestic varieties have been, and this may well make a
wide diiference in the result. For we know how commonly
wild animals and plants, when taken from their natural
conditions and subjected to captivity, are rendered sterile ;
and the reproductive functions of organic beings which have
always lived and been slowly modified under natural con
ditions would probably in like manner be eminently sensitive
to the influence of an unnatural cross. Domesticated pro-
ductions, on the other hand, which, as shown by the mere fact
of their domestication, were not originally highly sensitive
to changes in their conditions of life, and which can now
generally resist with undiminished fertility repeated changes
of conditions, might be expected to produce varieties, which
would be little liable to have their reproductive powers inju-
riously affected by the act of crossing with other varieties
which had originated in a like manner.

Certain naturalists have recently laid too great stress, as it
appears to me, on the difference in fertility between varieties
and species when crossed. Some allied species of trees cannot
be grafted on one another, whilst all varieties can be so
grafted. Some allied animals are affected in a very different
manner by the same poison, but with varieties no such case
until recently was known ; whilst now it has been proved that
immunity from certain poisons sometimes stands in correla-
tion with the colour of the individuals of the same species.
The period of gestation generally differs much in distinct
sx)ecies, but with varieties until lately no such difference had
been observed. Here we have various phj^siological differences,
and no doubt others could be added, between one species and
another of the same genus, which do not occur, or occur with
extreme rarity, in the case of varieties ; and these differences
are apparently wholly or in chief part incidental on other
constitutional differences, just in the same manner as the
sterility of crossed species is incidental on differences confined
to the sexual sj^stem. Why, then, should these latter differ-
ences, however serviceable they may indirectly be in keej)ing

Chap. XIX. HYBRIDISM. 175

the inhabitants of the same country distinct, be thought of
such paramount importance, in comparison with other inci-
dental and functional differences ? No sufficient answer to
this question can be given. Hence the fact that widely
distinct domestic varieties are, with rare exceptions, perfectly
fertile when crossed, and produce fertile offspring, whilst
closely allied species are, with rare exceptions, more or less
sterile, is not nearly so formidable an objection as it appears
at first to the theory of the common descent of allied species.

176 SELECTION. Chap. XX

CHAPTER XX.

SELECTION BY MAX.

SELJECTION A DIFFICULT ART — METHODICAL, UNCONSCIOUS, AND NATURAL
SELECTION — RESULTS OF METHODICAL SELECTION — CARE TAKEN IN SE-
LECTION SELECTION WITH PLANTS — SELECTION CARRIED ON BY THE

ANCIENTS AND BY SE3II-CIVILISED PEOPLE — UNIMPORTANT CHARACTERS

OFTEN ATTENDED TO — UNCONSCIOUS SELECTION AS CIRCUMSTANCES

SLOWLY CHANGE, SO HAVE OUR DOMESTICATED ANIMALS CHANGED
THROUGH THE ACTION OF UNCONSCIOUS SELECTION — INFLUENCE OF
DIFFERENT BREEDEUS ON THE SAME SUB-VARIETY — PLANTS AS AFFECTED
BY UNCONSCIOUS SELECTION — EFFECTS OF SELECTION AS SHOWN BY THE
GREAT AJIOUNT OF DIFFERENCE IN THE PARTS MOST VALUED BY MAN.

The power of Selection, whether exercised b}'' man, or brought
into play under nature through the struggle for existence and
the consequent survival of the fittest, absolutely depends on
the variability of organic beings. Without variability
nothing can be effected; slight individual differences, how-
ever, suffice for the work, and are probably the chief or sole
means in the production of new species. Hence our dis-
cussion on the causes and laws of variability ought in strict
order to have preceded the present subject, as well as inheri-
tance, crossing, &c. ; but practically the present arrange-
ment has been found the most convenient. Man does not
attempt to cause variability ; though he unintentionally effects
this by exposing organisms to new conditions of life, and by
crossing breeds already formed. But variability being granted,
he works wonders. Unless some degree of selection be exer-
cised, the free commingling of the individuals of the same
variety soon obliterates, as we have previously seen, the
slight differences which arise, and gives uniformity of cha-
racter to the whole body of individuals. In separated
districts, long-continued exposure to different conditions of
life may produce new races without the aid of selection ; but
to this subject of the direct action of the conditions of life
I shall recur in a future chapter.

UHAP. AX. SELECTION. 177

When animals or plants are born with some conspicuous
and firmly inherited new character, selection is reduced to the
preservation of such individuals, and to the subsequent pre-
vention of. crosses ; so that nothing more need be said on the
subject. But in the great majority of cases a new character,
or some superiority in an old character, is at first faintly
pronounced, and is not strongly inherited ; and then the full
difficulty of selection is experienced. Indomitable patience,
the finest powers of discrimination, and sound judgment must
be exercised during many years. A clearly predetermined
object must be kept steadily in view. Few men are endowed
with all these qualities, especially with that of discriminating
very slight differences ; judgment can be acquired only by
long experience ; but if an^^ of these qualities be wanting,
the labour of a life may be thrown away. I have been
astonished when celebrated breeders, whose skill and judg-
ment have been proved by their success at exhibitions, have
shown me their animals, which appeared all alike, and have
assigned their reasons for matching this and that individual.
The importance of the great principle of Selection mainly lies
in this power of selecting scarcely appreciable differences,
which nevertheless are found to be transmissible, and which
can be accumulated until the result is made manifest to the
ejes of every beholder.

The principle of selection may be conveniently divided into
three kinds. Methodical selection is that which guides a man
who systematically endeavours to modify a breed according to
some predetermined standard. Unconscious selection is that
which follows from men naturally preserving the most valued
and destroying the less valued individuals, without any
thought of altering the breed ; and undoubtedly this process
slowly works great changes. Unconscious selection graduates
into methodical, and only extreme cases can be distinctly
separated ; for he who preserves a useful or perfect animal
will generally breed from it with the hope of getting offspring
of the same character ; but as long a6 he has not a prede-
termined purpose to improve the breed, he may be said to be
selecting unconsciously.^ Lastly, we have Natural selection,

^ The ternj unconscious selection has been objected to as a contradiction ;

178 SELECTION. Chap. XX.

which implies that the individnals which are best fitted for
the complex, and in the course of ages changing conditions to
which they are exposed, generally survive and procreate their
kind. With domestic productions, natural selection comes to
a certain extent into action, independently of, and even in
opposition to, the will of man.

MetJiodical Selection. — "VThat man has effected within recent
times in England by methodical selection is clearly shown by
our exhibitions of improved quadrupeds and fancy birds.
With respect to cattle, sheep, and pigs, we owe their great
improvement to a long series of well-known names — Bake-
well, Colling, Ellman, Bates, Jonas Webb, Lords Leicester
and Western, Fisher Hobbs, and others. Agricultural writers
are unanimous on the power of selection : any number of
statements to this effect could be quoted ; a few will suffice.
Youatt, a sagacious and experienced observer, writes,^ the
principle of selection is " that which enables the agricul-
turist, not only to modify the character of his flock, but to
change it altogether." A great breeder of Shorthorns ^ says,
" In the anatomy of the shoulder modern breeders have made
" great improvement on the Ketton shorthorns by correcting
" the defect in the knuckle or shoulder-joint, and by laying
" the top of the shoulder more snugly in the crop, and thereby

" filling up the hollow behind it The eye has its

" fashion at different periods : at one time the eye high and

*' outstanding from the head, and at another time the sleepy

' eye sunk into the head ; but these extremes have merged

* into the medium of a full, clear and prominent eye with a

placid look."

Again, hear what an excellent judge of pigs * says : " The

' legs should be no longer than just to prevent the animal's

" belly from trailing on the ground. The leg is the least

but see some excellent observations ^ ' On Sheep,' 1838, p. 60.

on this head by Prof. Huxley (' Nat. ^ Mr, J. Wright on Shorthorn

Hist. Review,' Oct. 1864, p. 578), who Cattle, in ' Journal of Royal Agricult

remarks that when the wind heaps Soc.,' vol, vii. pp. 208, 209.

up sand-dunes it sifts and uncon- * H, D. Richardson * On Pigs,' 184-7,

sciously selects from the gravel on the p. 44,

beach grains of sand of equal size.

Chap. XX. METHODICAL SELECTION. 179

" profitable portion of the hog, and we therefore require no
*' more of it than is absolutely necessary for the support of
" the rest." Let any one compare the wild-boar with any
improved breed, and he will see how effectually the legs have
been shortened.

Few persons, except breeders, are aware of the systematic
care taken in selecting animals, and of the necessity of having
a clear and almost prophetic vision into futurit}^. Lord
Spencer's skill and judgment were well kno'vvn; and he
writes,^ " It is therefore very desirable, before any man com-
" mences to breed either cattle or sheep, that he should make
" up his mind to the shape and qualities he wishes to obtain,
"and steadily pursue this object." Lord Somerville, in
speaking of the marvellous improvement of the Kew Leicester
sheep, effected by Bakewell and his successors, says, " It
would seem as if they had first drawn a perfect form, aud
then given it life." Youatt ^ urges the necessity of annually
drafting each flock, as many animals will certainly degenerate
" from the standard of excellence which the breeder has
established in his own mind." Even with a bird of such
little importance as the canary, long ago (1780-1790) rales
were established, and a standard of perfection was fixed ac-
cording: to which the London fanciers tried to breed the
several sub- varieties.' A great winner of prizes at the Pigeon -
shows,^ in describing the short-faced Almond Tumbler, ssljs,
" There are many first-rate fanciers who are particularly
" partial to what is called the goldfinch-beak, which is very
" beautiful ; others say, take a full-size round cherry then
" take a barleycorn, and judiciously placing and thrusting it
" into the cherry, form as it were your beak ; and that is not
" all, for it will form a good head and beak, provided, as I
"said before, it is judiciously done; others take an oat; but
" as I think the goldfinch-beak the handsomest, I would advi-e
" the inexperienced fancier to get the head of a goldfinch, and
"keep it by him for his observation." Wonderfully different

^ * Journal of Royal Agricult. Sue.,' vol. viii., 1835, p. 618.
rol. i. p. 24. * * A treatise on the Art of Breed-

« ' On Sheep,' pp. 520, 319. ing the Almond Tumbler,' 1851, p. 9.
^ Loudon's ' Mag. of Nat. Hist.,'

180 SELECTION. Chap. XX.

as are tlie "beaks of the rock pigeon and goldfincli, the end
has nndoubtedly been nearly gained, as far as external shape
and proportions are concerned.

Kot only should our animals be examined with the greatest
care whilst alive, but, as Anderson remarks,^ their carcases
should be scrutinised, " so as to breed from the descendants
of such only as, in the language of the butcher, cut up well."
The " grain of the meat " in cattle, and its being well marbled
with fat,^° and the greater or less accumulation of fat in the
abdomen of our sheep, have been attended to with success.
So with poultry, a writer,^^ speaking of Cochin-China fowls,
which are said to differ much in the quality of their flesh,
says, " the best mode is to purchase two young brother-cocks,
" kill, dress, and serve up one ; if he be indifferent, similarly
" dispose of the other, and try again ; if, however, he be fine
" and well-flavoureti, his brother will not be amiss for breeding
" purposes for the table."

The great principle of the division of labour has been
brought to bear on selection. In certain districts ^^ " the
" breeding of bulls is confined to a very limited number of
" persons, who by devoting their whole attention to this
*' department, are able from jea,T to year to furnish a class of
" bulls which are steadily improving the general breed of the
" district." The rearing and letting of choice rams Las long
been, as is well known, a chief source of profit to several
eminent breeders. In parts of Germany this principle is
carried with merino sheep to an extreme point.^^ So impor-
" tant is the proper selection of breeding animals considered,
" that the best flock-masters do not trust to their own judg-
" m.ent or to that of their shepherds, but employ persons called
" ' sheep-classifiers,' who make it their special business to
" attend to this part of the management of several flocks,
" and thus to preserve, or if possible to improve, the best
' qualities of both parents in the lambs." In Saxony, " when

® ' Recreations in Agriculture,' vol. Agricult. Soc.,' quoted in ' Gard.

ii. p. 409. Chronicle,' 1844, p. 29.

'" Youatt on Cattle, pp. 191, 227. " Simmonds, quoted in * Gard.

" Ferguson, * Prize Poultry,' 1854, Chronicle,' 1855, p. 637. Aud for

p. 208, the second quotation, see Youatt on

>2 Wilson, in 'Transact. Highland Sheep, p. 171.

Chap. XX. METHODICAL SELECTION. 181

" the lambs are weaned, eacli in his turn is placed upou a
" table that his wool and form may be minutely observed.
" The finest are selected for breeding and receive a first
" mark. When they are one year old, and prior to shearing
" them, another close examination of those previously marked
" takes place : those in which no defect can be found receive
" a second mark, and the rest are condemned. A few months
' afterwards a third and last scrutiny is made ; the prime
* rams and ewes receive a third and final mark, but the
" slightest blemish is sufficient to cause the rejection of the
" animal." These sheep are bred and valued almost ex-
clusively for the fineness of their wool ; and the result
corresponds with the labour bestowed on their selection.
Instruments have been invented to measure accurately the
thickness of the fibres ; and " an Austrian fleece has been
produced of which twelve hairs equalled in thickness one
from a Leicester sheep."

Throughout the world, wherever silk is produced, the
greatest care is bestowed on selecting the cocoons from which
the moths for breeding are to be reared. A careful cultivator^'*
likewise examines the moths themselves, and destroys those
that are not perfect. But what more immediately concerns
us is that certain families in France devote themselves to
raising eggs for sale.^^ In China, near Shanghai, the in-
habitants of two small districts have the privilege of raising
eggs for the whole surrounding country, and that they may
give up their whole time to this business, they are interdicted
by law from producing silk.^^

The care which successful breeders take in matching their
birds is surprising. Sir John Sebright, whose fame is per-
petuated by the " Sebright Bantam," used to spend " two and
three days in examining, consulting, and disputing with a
friend which were the best of five or six birds." ^^ Mr. Bult,
whose pouter-pigeons won so many prizes, and were exported
to North America under the charge of a man sent on purpose,

" Robinet, ' Vers a Soie,' 1848, p. " M. Simon, in < Bull, de la Soc.

271. d'Acclimat.,' torn, ix., 1862, p. 221.

" Quatrefages, ' Les Maladies du ^^ ' The Poultry Chronicle,' vol. i.,

Ver k Soie,' 1859, p. 101. 1854, p. 607.

30

182 SELECTION. Chap. XX.

told me that he always deliberated for several dsijs before he
matched each pair. Hence we can understand the advice of
an eminent fancier, who writes,^^ " I would here particularly
" guard you against having too great a variety of pigeons,
" otherwise you will know a little of all, but nothing about
" one as it ought to be known." Apparently it transcends
the power of the human intellect to breed all kinds : "it
" is possible that there may be a few fanciers that have a
" good general knowledge of fancy pigeons ; but there are
" many more who labour under the delusion of supposing
" they know what they do not." The excellence of one sub-
variety, the Almond Tumbler, lies in the plumage, carriage,
head, beak, and eye ; but it is too presumptuous in the
beginner to try for all these points. The great judge above
quoted says, " There are some young fanciers who are over-
" covetous, who go for all the above five properties at once ;
they have their reward b}' getting nothing." We thus see
that breeding even fanc}'' pigeons is no simple art : we may
smile at the solemnity of these precepts, but he who laughs
will win no prizes.

What methodical selection has effected for our animals is
sufficiently proved, as already remarked, by our Exhibitions.
So greatly were the sheep belonging to some of the earlier
breeders, such as Bakewell and Lord Western, changed, that
many persons could not be persuaded that they had not been
crossed. Our pigs, as Mr. Gorringham remarks, ^^ during the
last twenty years have undergone, through rigorous selection
together with crossing, a complete metamorphosis. The first
exhibition for poultry was held in the Zoological Gardens in
1845; and the improvement effected since that time has been
great. As Mr. Bailey, the great judge, remarked to me, it
was formerly ordered that the comb of the Spanish cock
should be upright, and in four or five years all good birds
had upright combs ; it was ordered that the Polish cock
should have no comb or wattles, and now a bird thus fur-
nished would be at once disqualified ; beards were ordered,

i« J. M. Eaton, 'A Treatise on 1851, p. 11.
Fancy Pigeons,' 1852, p. xiv., and *^ 'Journal Royal Agricultural

A Treatise oa the Almond Tumbler,' Soc.,' vol. vi. p. 22.

Chap. XX. METHODICAL SELECTIOX. 183

and out of fifty-seven pens lately (1860) exhibited at tlie
Crystal Palace, all had beards. So it has been in many other
cases. But in all cases the judges order only what is occa-
sionally produced and what can be improved and rendered
constant by selection. The steady increase in weight during
the last few years in our fowls, turkeys, ducks, and geese is
notorious ; " six-pound ducks are now common, whereas four
pounds was formerly the average." As the time required to
make a change has not often been recorded, it may be
worth mentioning that it took Mr. Wicking thirteen years
to put a clean white head on an almond tumbler's body,
" a triumph," sa^^s another fancier, " of which he may be
justly proud." ^°

Mr. Toilet, of Betley Hall, selected cows, and especially
bulls, descended from good milkers, for the sole purpose of
improving his cattle for the production of cheese ; he steadily
tested the milk with the lactometer, and in eight years he
increased, as I was informed by him, the product in propor-
tion of four to three. Here is a curious case ^^ of steady but
slow progress, with the end not as yet fully attained : in
1784 a race of silkworms was introduced into France, in
which one hundred in the thousand failed to produce white
cocoons ; but now after careful selection during sixty-five
generations, the proportion of yellow cocoons has been
reduced to thirty -five in the thousand.

With plants selection has been followed with the same
good result as with animals. But the process is simpler,
for plants in the great majority of cases bear both sexes.
Nevertheless, with most kinds it is necessary to take as much
care to prevent crosses as with animals or unisexual plants ;
but with some plants, such as peas, this care is not necessary.
With all improved plants, excepting of course those which
are propagated by buds, cuttings, &c., it is almost indispen-
sable to examine the seedlings and destroy those which
depart from the proper type. This is called " roguing," and
is, in fact, a form of selection, like the rejection of inferior
animals. Experienced horticulturists and agriculturists

20 * Poultry Chronicle,' vol. ii., " jgi^j^ Geoffroy St.-Hilaire, ' Hist

1855, p. 596. Nat. Gen.,' torn. iii. p. 254.

184 SELECTION. Chap. XX.

incessantly urge every one to preserve the finest plants for
the production of seed.

Although plants often present much more conspicuous
variations than animals, yet the closest attention is generally
requisite to detect each slight and favourable change. Mr.
Masters relates ^^ how "many a patient hour was devoted,"
whilst he was young, to the detection of differences in peas
intended for seed. Mr. Barnet ^^ remarks that the old scarlet
American strawberr}^ was cultivated for more than a century
without producing a single variety ; and another writer ob-
serves how singular it was that when gardeners first began
to attend to this fruit it began to vary ; the truth no doubt
being that it had always varied, but that, until slight vari-
ations were selected and propagated by seed, no conspicuous
result was obtained. The finest shades of difference in wheat
have been discriminated and selected with almost as much
care as, in the case of the higher animals, for instance by
Col. Le Couteur and more especially by Major Hallett.

It may be worth while to give a few examples of method-
ical selection with plants ; but in fact the great improvement
of all our anciently cultivated plants may be attributed to
« selection long carried on, in part methodically, and in part
unconsciously. I have shown in a former chapter how the
weight of the gooseberry has been increased by systematic
selection and culture. The flowers of the Heartsease have
been similarly increased in size and regularity of outline.
With the Cineraria, Mr. Glenny ^^ " was bold enough when
" the flowers were ragged and starry and ill defined in colour,
" to fix a standard which was then considered outrageously
*' high and impossible, and which, even if reached, it was
*' said, we should be no gainers by, as it would spoil the
*' beauty of the flowers. He maintained that he was right;
" and the event has proved it to be so." The doubling of
flowers has several times been effected by careful selection :
the Eev. W. Williamson,-^ after sowing during several years

22 'Gardener's Chron.,' 1850, p. '-4 tjoumal of Horticulture,' 1862,

198. p. 369.

" * Transact. Hort, Soc.,' vol. vi. p. 's < Transact. Hort. Soc.,' vol. iv.

152. p. 381.

Chap. XX. BY THE ANCIENTS. 185

seed of Anemone coronaria, found a plant with one additional
petal ; he sowed the seed of this, and by pei severance in the
same course obtained several varieties with six or seven row^s
of petals. The single Scotch rose was doubled, and yielded
eight good varieties in nine or ten years. ^^ The Canterbury
bell (^Campanula medium') was doubled by careful selection in
four generations.^^ In four years Mr. Buckman,^^ by culture
and careful selection, converted parsnips, raised from wild
seed, into a new and good variety. By selection during a
long course of years, the early maturity of peas has been
hastened by between ten and twenty-one days.^^ A more
curious case is offered by the beet plant, which since its culti-
vation in France, has almost exactly doubled its yield of
sugar. This has been effected by the most careful selection ;
the specific gravity of the roots being regularly tested, and
the best roots saved for the production of seed.^*^

Stlection hy Ancient and Semi- civilised People.

In attributing so much importance to the selection of
animals and plants, it may be objected, that methodical selec-
tion would not have been carried on during ancient times.
A distinguished naturalist considers it as absurd to suppose
that semi-civilised people should have practised selection of
any kind. Undoubtedly the principle has been systematically
acknowledged and followed to a far greater extent within the
last hundred years than at any former period, and a corre-
sponding result has been gained ; but it would be a greater
error to suppose, as we shall immediately see, that its impor-
tance was not recognised and acted on during the most ancient
times, and by semi-civilised people. I should premise that
many facts now to be given only show that care was taken
in breeding ; but when this is the case, selection is almost
sure to be practised to a certain extent. We shall hereafter
be enabled better to judge how far selection, when only occa-

"^^ ' Transact. Hort. Soc.,' vol. iv. p. vi. p. 96 ; Mr. Barnes, in ' Gard.

285. Chronicle,' 1844-, p. 476.

2' Rev. W. Bromehead, in 'Gard. ^o Qodron, 'De I'Espfece,' 1859,

Chronicle,' 1857, p. 550. torn. ii. p. 69; 'Gard. Chronicle/

2» 'Gard. Chronicle,' 1862, p. 721. 1854, p. 258.

'^ Dr. Anderson, in ' The Bee,' vol.

186 SELECTION. Chap. XX.

Bionally carried on, by a few of the iuhabitants of a country,
will slowly produce a great effect.

In a well known passage in the thirtieth chapter of Genesis,
rules are given for influencing, as was then thought possible,
the colour of sheep ; and speckled and dark breeds are spoken
of as being kept separate. By the time of David the fleece
was likened to snow. Youatt,^^ who has discussed all the
passages in relation to breeding in the Old Testament, con-
cludes that at this early period " some of the best principles
of breeding must have been steadily and long pursued." It
was ordered, according to Moses, that " Thou shalt not let thy
cattle gender with a diverse kind ; " but mules were pur-
chased,^^ so that at this early period other nations must have
crossed the horse and ass. It is said^^ that Erichthonius,
some generations before the Trojan war, had many brood-
mares, " which by his care and judgment in the choice of
stallions produced a breed of horses superior to any in the
surrounding countries." Homer (Book v.) speaks of ^Eneas'
horses as bred from mares which were put to the steeds of
Laomedon. Plato, in his ' Eepublic,' says to Glaucus, " I see
that you raise at your house a great many dogs for the chase.
Do you take care about breeding and pairing them ? Among
animals of good blood, are there not alwa3^s some which are
superior to the rest ? " To which Glaucus answers in the
affirmative.^* Alexander the Great selected the finest Indian
cattle to send to Macedonia to improve the breed.^^ Acccord-
ing to Pliny,^^ King Pyrrhus had an especiall}' valuable
breed of oxen : and he did not suffer the bulls and cows to
come together till four years old, that the breed might not
degenerate. Virgil, in his Georgics (lib. iii.), gives as strong
advice as any modern agriculturist could do, carefull}'" to select
the breeding stock ; " to note the tribe, the lineage, and the
sire ; whom to reserve for husband of the herd; " — to brand
the progen}^ ; — to select sheep of the purest white, and to
examine if their tongues are swarthy. We have seen that the

31 On Sheep, p. 18. ^ Dr. Dally, trssil(?.ted in * Anthro-

32 Volz, ' Beitriige zur Kulturge- pological Review,' May 1864, p. 101.
schichte,' 1852, s. 47. ^""Volz, 'Beitrage,' kc, 1852, s.

" Mitford's 'History of Greece,' 80.
vol. i. p. 73. »« ' History of the World,' ch. 45.

Chap. XX. BY THE ANCIENTS. 187

Romans kept pedigrees of tlieir pigeons, and this wonld have
been a senseless proceeding had not great care been taken in
breeding them. Columella gives detailed instructions about
breeding fowls : " Let the breeding hens therefore be of a
choice colour, " a robust body, square-built, full- breasted, vv^ith
" large heads, with upright and bright-red combs. Those
" are believed to be the best bred which have five toes." ^^
According to Tacitus, the Celts attended to the races of their
domestic animals ; and Ceesar states that they paid high
prices to merchants for fine imported horses.^** In regard to
plants, Virgil speaks of yearly culling the largest seeds ; and
Celsus says, " where the corn and crop is but small, we must
pick out the best ears of corn, and of them lay up our seed
separately by itself." ^^

Coming down the stream of time, we may be brief. At
about the beginning of the ninth century Charlemagne
expressly ordered his officers to take great care of his stallions ;
and if any proved bad or old, to forewarn him in good time
before they were put to the mares.*^ Even in a country so
little civilised as Ireland during the ninth century, it would
appear from some ancient verses,*^ describing a ransom
demanded by Cormac, that animals from particular places,
or having a particular character, were valued. Thus it
is said, —

Two pigs of the pigs of Mac Lir,

A ram and ewe both round and red,

I brought with me from Aeugus.

1 brought with me a stallion and a mare

From the beautiful stud of Manannan,

A bull and a white cow from Druim Cain.

Athelstan, in 930, received running-horses as a present from
Germany ; and he prohibited the exportation of English
horses. King John imported " one hundred chosen stallions
from Flanders." ^^ On June 16th, 1305, the Prince of Wales

" 'Gardener's Chronicle,' 1848, p. *^ Sir W. Wilde, an 'Essay on Un-

323. manufactured Animal Remains,' &c.,

»* Reynier, ' De I'Economie des 1860, p. 1 1.

Celtes,' 1818, pp. 487, 503. « Col. Hamilton Smith, 'Nat.

^^ Le Couteur on Wheat, p. 15. Library,' vol. xii., Horses, pp. 135,

*« Michel, ' Des Haras,' 1861, p. 84, 140.

188

SELECTION.

Chap. XX.

wrote to the Archbishop of Canterbury, begging for the loan
of any choice stallion, and promising its return at the end of
the season.^-^ There are numerous records at ancient periods
in English history of the importation of choice animals of
vaiious kinds, and of foolish laws against their exportation.
In the reigns of Henry VII. and VIII. it was ordered that
the magistrates, at Michaelmas, should scour the heaths and
commons, and destroy all mares beneath a certain size."*^
Some of our earlier kings passed laws against the slaughter-
ing rams of any good breed before they were seven years old,
so that they might have time to breed. In Spain Cardinal
Ximenes issued, in 1509, regulations on the selection of good
rams for breeding.^^

The Emperor Akbar Khan before the year 1600 is said to
have " wonderfully improved " his pigeons by crossing the
breeds ; and this necessarilj^ implies careful selection. About
the same period the Dutch attended with the greatest care
to the breeding of these birds. Belon in 1555 says that good
managers in France examined the colour of their goslings in
order to get geese of a white colour and better kinds. Mark-
ham in 1631 tells the breeder "to elect the largest and good-
liest conies," and enters into minute details. Even with
respect to seeds of plants for the flower-garden. Sir J. Hanmer
writing about the year 1660*^ says, in "choosing seed, the
best seed is the most weighty, and is had from the lustiest
and most vigorous stems ; " and he then gives rules about
leaving only a few flowers on plants for seed ; so that even
such details were attended to in our flower-gardens two
hundred years ago. In order to show that selection has been
silently carried on in places where it would not have been
expected, I may add that in the middle of the last century,
in a remote part of North America, Mr. Cooper improved by
careful selection all his vegetables, " so that they were greatly
" superior to those of any other person. When his radishes,

« Michel, ' Des Haras,' p. 90.

** Mr. Baker, 'History of the
Horse,' ' Veterinary,' vol. xiii. p. 423.

** M. I'Abbe Carlier, in ' Journal
de Physique,' vol. xxiv,, 1784, p. 181 ;
this memoir contains much informa-

tion on the ancient selection of sheep ;
and is my authority for rams not
being killed young in England.

"« 'Gardener's Chronicle,' 184 3, p,
389.

Chap. XX. BY SEMI-CIVILISED PEOPLE. 189

*' for instance, are fit for use, he takes ten or twelve that he
" most approves, and plants them at least 100 yards from
" others that blossom at the same time. In the same manner
" he treats all his other plants, varying the circumstances
*' according to their nature." *^

In the great work on China published in the last century
by the Jesuits, and which is chiefly compiled from ancient
Chinese encyclopaedias, it is said that with sheep " improving
*' the breed consists in choosing with particular care the
" lambs which are destined for propagation, in nourishing
*' them well, and in keeping the flocks separate." The same
princij)les were applied by the Chinese to various plants and
fruit-trees.^^ An imperial edict recommends the choice of
seed of remarkable size ; and selection was practised even
by imperial hands, for it is said that the Ya-mi, or imperial
rice, was noticed at an ancient jDcriod in a field by the Em-
peror Khang-hi, Tvas saved and cultivated in his garden, and
has since become valuable from being the only kind which
will grow north of the Great Wall."^^ Even with flowers,
the tree pseony (P. moutan) has been cultivated, according to
Chinese traditions, for 1400 years; between 200 and 300
varieties have been raised, w^hich are cherished like tulips
formerly were by the Dutch.^^

Turning now to semi-civilised people and to savages : it
occurred to me, from what I had seen of several parts of South
America, where fences do not exist, and where the animals are
of little value, that there would be absolutely no care in
breeding or selecting them ; and this to a large extent is
true. Eoulin,^^ however, describes in Columbia a naked race
of cattle, w^hich are not allowed to increase, on account of
their delicate constitution. According to Azara ^- horses are
often born in Paraguay with curly hair ; but, as the natives

*^ * Communications to Board of to Khang-hi, sec Hue's ' Chinese Em-
Agriculture,' quoted in Dr. Darwin's pire,' p. 311.
Phytologia,' 1800, p. 451. *' Anderson, in 'Linn. Transact.,'

** ' Memoire sur les Chinois,' 1786, vol. sii. p. 253.

tom. xi. p. 55; torn. v. p. 507. ^' 'Mem. de I'Acad.' (divers -sa-

*^ 'Recherches sur I'Agriculture vants), tom. vi., 1835, p. 333.

des Chinois,' par L. D'Hervey Saint- " ' Des Quadrupedes du Paraguay,'

Denys, 1850, p. 229. With respect 1801, tom. ii. pp. 333, 371.

190 SELECTION. Chap. XX.

do not like them, tliey are destroyed. On the other hand,
Azara states that a hornless bull, born in 1770, was preserved
and propagated its race. I was informed of the existence in
Banda Oriental of a breed with reversed hair ; and the extra-
ordinary niata cattle first appeared and have since been kept
distinct in La Plata. Hence certain conspicuous variations
have been preserved, and others have been habitually
destroyed, in these countries, which are so little favourable
for careful selection. We have also seen that the inhabitants
sometimes introduce fresh cattle on their estates to prevent the
evil effects of close interbreeding. On the other hand, I have
heard on reliable authority that the Gauchos of the Pampas
never take any pains in selecting the best bulls or stallions
for breeding ; and this probably accounts for the cattle and
horses being remarkably uniform in character throughout the
immense range of the Argentine republic.

Looking to the Old World, in the Sahara Desert " The
" Touareg is as careful in the selection of his breeding Mahari
" (a fine race of the dromedary) as the Arab is in that of his
" horse. Ilie pedigrees are handed down, and many a drome-
" dary can boast a genealogy far longer than the descendants
" of the Darley Arabian." ^■^ According to Pallas the Mongo-
lians endeavour to breed the Yaks or horse-tailed buffaloes
with white tails, for these are sold to the Chinese mandarins
as fly-flappers ; and Moorcroft, about seventy years after
Pallas, found that white-tailed animals were still selected for
breeding.^*

We have seen in the chapter on the Dog that savages in
different parts of North America and in Guiana cross their
dogs with wild Canida^., as did the ancient Gauls, according
to Pliny. This was done to give their dogs strength and
vigour, in the same way as the keepers in large warrens
now sometimes cross their ferrets (as I have been informed by
Mr. Yarrell) with the wild polecat, " to give them more devil."
According to Yarro, the wild ass was formerly caught and
crossed with the tame animal to improve the breed, iu the

" 'The Great Sahara,' by the Rev. burg,' 1777, p. 249, Moorcroft and
H. B. Tristram, 1860, p. 238. Trebeck, ' Travels in the Himalayan

*< Pallas. 'Act. Acad. St. Peters- Provinces,' 1841.

Chap. XX. BY SEMI-CIVILISED PEOPLE. 191

Bame manner as at tlie present day tlie natives of Java some-
times drive their cattle into the forests to cross with the wild
Banteng (^Bos sondaicus).^^ In Korthern Siberia, among the
Ost3'aks, the dogs vary in markings in different districts, but
in each place they are spotted black and white in a remark-
ably uniform manner ; ^'^ and from this fact alone we may
infer careful breeding, more especially as the dogs of one
locality are famed throughout the country for their superio-
rity. I have heard of certain tribes of Esquimaux who take
pride in their teams of dogs being uniformly coloured. In
Guiana, as Sir R. Schomburgk informs me,^'^ the dogs of the
Turuma Indians are highly valued and extensively bartered :
the price of a good one is the same as that given for a wife :
they are kept in a sort of cage, and the Indians " take great
cai'e when the female is in season to prevent her uniting with
a dog of an inferior description." The Indians told Sir
Eobert that, if a dog proved bad or useless, he was not killed,
but was left to die from sheer neglect. Hardly any nation is
more barbarous than the Fuegians, but I hear from Mr.
Bridges, the Catechist to the Mission, that, " when these
" savages have a large, strong, and active bitch, they take
" care to put her to a fine dog, and even take care to feed
" her well, that her young may be strong and well favoured."
In the interior of Africa, negroes, who have not associated
with white men, show great anxiety to improve their animals ;
they " always choose the larger and stronger males for stock ;"
the Malakolo were much pleased at Livingstone's promise to
send them a bull, and some Bakalolo carried a live cock all
the way from Loanda into the interior.^^ At Falaba Mr.
Winwood Eeade noticed an unusually fine horse, and the
negro King informed him that " the owner was noted for his
" skill in breeding horses." Further south on the same
continent, Andersson states that he has known a Damara
give two fine oxen for a dog which struck his fancy. The

*' Quoted from Raffles, in the graph. See.,' vol. xiii. part i. p. 65.
* Indian Field,' 1859, p. 196: for ^^ Livingstone's ' First Travels,' pp.

Varro, see Pallas, ut supra. 191, 439, 565 ; see also ' Expedition to

" Erman's 'Travels in Siberia,' the Zambesi,' 1865, p. 495, for an

\iXig. translat., vol. i. p. 4-53. analogous case respecting a good

^"^ See also ' Journal of R. Geo- breed of goats.

192 SELECTION. Chap. XX

Damaras take great delight in having whole droves of cattle
of the same colour, and they prize their oxen in proportion to
the size of their horns. "The Namaquas have a perfect
" mania for a uniform team ; and almost all the people of
*' Southern Africa value their cattle next to their women, and
" take a pride in possessing animals that look high-bred."
'* They rarely or never make use of a handsome animal as a
" beast of burden."^^ The power of discrimination which
these savages possess is wonderful, and they can recognise to
which tribe any cattle belong. Mr. Andersson further in-
forms me that the natives frequently match a particular bull
with a particular cow.

The most curious case of selection by semi-civilised people,
or indeed by any people, which I have found recorded, is that
given by Garcilazo de la Vega, a descendant of the Incas, as
having been practised in Peru before the country was sub-
jugated by the Spaniards. ^° The Incas annually held great
hunts, when all the wild animals were driven from an im-
mense circuit to a central point. The beasts of prey were
first destroj^ed as injurious. The wild Guanacos and Vicunas
were sheared ; the old males and females killed, and the
others set at liberty. The various kinds of deer were
examined ; the old males and females were likewise killed ;
" but the young females, with a certain number of males,
selected from the most beautiful and strong," w^ere given
their freedom. Here, then, we have selection by man aiding
natural selection. So that the Incas followed exactly the
reverse system of that which our Scottish sportsman are
accused of following, namely, of steadily killing the finest
stags, thus causing the whole race to degenerate.^^ In regard
to the domesticated llamas and alpacas, they were separated
in the time of the Incas according to colour : and if by chance
one in a flock was born of the wrong colour, it was eventually
put into another flock.

In the genus Auchenia there are four forms, — the Guanaco

*® Andersson's 'Travels in South 136.
A-frica,' pp. 232, 318, 319. " 'The Natural History of Dee

«<» Dr. Vavasseur, in < Bull, de la Side,' 1855, p. 476.
See. d'Acclimat.,' torn, viii., 1861, p.

Chap. XX. OF TRIFLING CHARACTERS. 193

and Vicuna, found wild and undoubtedly distinct species ;
the Llama and Alpaca, known only in a domesticated con-
dition. These four animals appear so different, that most
naturalists, especially those who have studied these animals
in their native country, maintain that they are specifically
distinct, notwithstanding that no one pretends to have seen
a wild llama or alpaca. Mr. Ledger, however, who has closely
studied these animals both in Peru and during their exporta-
tion to Australia, and who has made many experiments on
their propagation, adduces arguments ^^ which seem to me
conclusive, that the llama is the domesticated descendant of
the guanaco, and the alpaca of the vicuna. And now that we
know that these animals were systematically bred and selected
many centuries ago, there is nothing surprising in the great
amount of change which they have undergone.

It appeared to me at one time probable that, though
ancient and semi-civilised people might have attended to the
improvement of their more useful animals in essential points,
yet that they would have disregarded unimportant characters.
But human nature is the same throughout the world : fashion
everywhere reigns supreme, and man is apt to value whatever
he may chance to possess. We have seen that in South
America the niata cattle, which certainly are not made useful
by their shortened faces and upturned nostrils, have been
preserved. The Damaras of South Africa value their cattle for
uniformity of colour and enormously long horns. And I will
now show that there is hardly any peculiarity in our most
useful animals which, from fashion, superstition, or some
other motive, has not been valued, and consequently pre-
served. With respect to cattle, " an early record," according
to Youatt,^^ " speaks of a hundred white cows with red ears
" being demanded as a compensation by the princes of North
" and South AVales. If the cattle were of a dark or black
"colour, 150 were to be presented." So that colour was
attended to in Wales before its subjugation by England. In
Central Africa, an ox that beats the ground with its tail is
killed ; and in South Africa some of the Damaras will not eat

« 'Bull, de la Soc. d'Acclimat.,' torn, vu., 1860, p. 457. «3 < Cattle,' p. 48.

194 SELECTION. Ch/lp. XX.

the flesh of a- spotted ox. The Kaffirs value an animal with
a musical voice ; and " at a sale in British Kaffraria the low
" of a heifer excited so much admiration that a sharp com
" petition si3rung up for her possession, and she realised a
*' considerable price." ^* "With respect to sheep, the Chinese
prefer rams without horns