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The variation of animals & plants under domestication, Volume 2 online

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THE VARIATION OF
ANIMALS AND PLANTS
UNDER DOMESTICA-
TION ....



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THE VARIATION OF

ANIMALS Sf PLANTS UNDER

DOMESTICATION

BY CHARLES DARWIN, M.A., LL.D., F.R.S.
EDITED BY FRANCIS DARWIN, FELLOW
OF CHRIST'S COLLEGE, CAMBRIDGE

POPULAR EDITION



IN TWO VOLUMES — VOL. 11.
WITH ILLUSTRATIONS



LONDON
JOHN MURRAY, ALBEMARLE STREET, W.

1905



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<1 ~



2. "IS









rRlSTKD BY

HAZEI.L, WATSON AND VINET, LD.,

LONDON AND ATLBSBURT.



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CONTENTS



CHAPTER XIII
iXHEKiTAKCE, Continued — revkesion oe atavism

DIFFERENT FORJiS OF REVERSION — IN PURE OR UNCROflBED BREEDS^ AS
IN PIGEONS^ FOWIJB^ HORNLESS CATTLE AND SHEEP^ IN CULTIVATED
PLANTS — REVERSION IN FERAL ANIMALB AND PLANTS — REVERSION
IN CROSSED VARIEnEB AND SPECIES — REVERSION THROUGH BUD-
PROPAOATION^ AND BT SEOMEl^TTB 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 —
JfONSTROSITIES — PELORIC FLOWERS DUE IN SOME CASES TO REVER-
SION Pages 1-44



CHAPTER XIV

tNHKEITAXCE, CO^Umued — fixedness of CHAEACTEE — PEE-
POTENCY SEXUAL LIMITATION COEEESPONDENCE OF AGE

FIXEDNESS OP CHARACTER APPARENTLY NOT DUE TO ANTIQUITY OF
INHERITANCB — PREPOTENCY OF TRANSMISSION IN INDIVIDUALS OF
THE SAME FAMILY^ IN CROSSED BREEDS AND SPBOIBB ; OFTF^
STRONGER IN ONE SEX THAN THE OTHER ; SOMETIMES DUE TO THE
SAME CHARACTER BEING PRESENT AND VISIBLE IN ONE BREED AND



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vi CONTENTS



LATENT IN THE OTHER — INHERITANCE AS LIMITED BY SEX —
NEWLY ACQUIRED CHARACTERS IN OUR DOMESTICATED ANIMAIiS
OFTEN TRANSMITTED BY ONE SEX ALONE^ SOMETIMES LOST BY ONE
SEX ALONE — INHERITANCE AT CORRESPONDING PERIODS OF UPE —
THE IMPORTANCE OF THE PRINCIPLE WITH RESPECT TO EMBRYO-
LOOT ; AS EXHIBITED IN DOMESTICATED ANIMALS ; AS EXHIBITED
IN THE APPEARANCE AND DISAPPEARANCE OF INHERITED DISEASES ;
SOMETIMES SUPERVENING EARLIER IN THE CHILD THAN IN THE
PARENT — SUMBfARY OF THE THREE PRECEDING CHAPTERS

Pages 45-75



CHAPTER XV

ON CROSSING

FREE INTERCROSSING OBLITERATES THE DIFFERENCES BETWEEN ALLIED
BREEDS — WHEN THE NUMBERS OF TWO COBiMINOUNO BREEDS ARK
UNEQUAL^ ONE ABSORBS THE OTHER — THE RATE OF ABSORPTION
DETERMINED BY PREPOTENCY OP TRANSMISSION^ BY THE CONDITIONS
OP LIFE, AND BY NATURAL SELECTION — ALL ORGANIC BEINGS

OCCASIONALLY INTERCROSS ; APPARENT EXCEPTIONS ON CERTAIN

CHARACTERS INCAPABLE OF FUSION ; CHIEFLY OR EXCLUSIVELY
THOSE WHICH HAVE SUDDENLY APPEARED IN THE INDI\1DUAL —
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 7^-94



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 VARIBTIBS DISTINCT, AS

THE PERIOD OP BREEDING AND SEXUAL PREFERENCE — VARIETIES
OP WHEAT SAID TO BE STERILE WHEN CROSSED — VARIETIES OF
MAIZE, VERBASCUM, HOLLYHOCK, GOURDS, MELONS, AND TOBACCO



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CONTENTS vii

RENDERED I!f SOME DEGREE MUTUALLY STERILE — ^DOMERICATION
ELDflNATEB THE TEIVDENCT TO flTERnJTT NATURAL TO SPBCIEB
WHEN CROSSED — ON THE INCREASED FERTfUTT OF UNOROMED
ANIMAIA AND PLANTS PROM DOMBBTICATION AND CULTIVATrON

P^;«6 95-112

CHAPTER X\II

ON THE GOOD EFFECTS OF CROSSING, AND ON THE EVIL
EFFECTS OF CLOSE INTERBBEEDIN6

DEFINITION OF CLOSE INTERRRBRDING — AUGMENTATION OF MORRID
TENDENCIES — GENERAL EVIDENCE OF THE GOOD EFFECTS DERIVED
FROM CROSSINO^ AND ON THE EVIL EFFECTS FROM CLOSE INTERBREED-
ING-— CATIXiE, CLOSELY INTBRRRED ; HALF-WILD CATTUI LONG
KEPT IN THE SAME PARKS — SHBBP — FALLOW-DEER — ^DOGS, RABBITS^
PIGS — ^MAN^ ORIGIN OP HIS ABHORRENCE OF INCBSTUOUS MARRIAGES
— FOWLS — ^PIGEONS — HIVE-BEEB — PLANTS^ GENERAL CONSIDERA-
TIONS ON THE BENHFITS DERIVED FROM CROSSING — MELONS, FRUIT-
TREES, PEAS, CABBAGES, WHEAT, AND FOREST-TREES — ON THE
INCREASED SIZE OF HYBRID PLANTS, NOT BZCLUSIVBLY DUB 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 SPBCIES — CON-
CLUSION 113-157



CHAPTER XVIII

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

ON THE GOOD DERIVED FROM SLIGHT CHANGES IN THE CONDITIONS OF
LIFE — STERILITY FROM CHANGED CONDITIONS, IN ANIMAI^, IN
THEIR NATIVE COUNTRY AND IN MENAGERIES — MAMMALS, BIRDS,
AND INSECTS — LOSS OF SECONDARY SEXUAL CHARACTERS AND OF
INOTINCTS — CAUSES OF STERILITY — STERILITY OF DOMESTICATED
ANIMAIJ9 FROM CHANGED CONDITIONS — SEXUAL INCOMPATIBILITY
OF INDIVIDUAL ANIMALS — STERIIJTY OF PT<ANTS FROM CHANGED



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viii CONTENTS

CONDITIONS OF UFB — CONTABEBCENCB OF THE ANTHERS — HON-
STROSITIBS AS A CAUSE OF STERILITY — DOUBLE FLOWERS — SEEDLESS
FRUIT — STERILITY FROM THE EXCESSIVE DEVELOPMENT OF THE
OROANS OF VEGETATION — FROM LONG-CONTINUED PROPAGATION
BY BUDS — INCIPIENT STERILITY THE PRIMARY CAUSE OF DOUBLE
FLOWERS AND SEEDLESS FRUIT PflgeS 168-196



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 OF LIFE — VARIETIES WHEN CROSSED NOT

INVARIABLY FERTILE ON THE DIFFERENCE IN FERTIUTY BETWEEN

CROSSED SPECIES AND VARIETIES — CONCLUSIONS WITH RESPECT TO
HYBRIDISM — LIGHT THROWN ON HYBRIDISM BY THE ILLEGITIMATE
PROGENY OP HETER08TYLED PLANTS — 8TERIUTY 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 VARIETIBB— CONCLUSION 197-218



CHAPTER XX

SELECTION BY MAN

SELECTION A DIFFICULT ART — METHODICAL^ UNCONSCIOUS^ AND NATURAL
SELBOnON — RESULTS OP METHODICAL SELECTION — CARE TAKEN IN
SELECTION— SELECTION WITH PLANTS — SELECTION CARRIED ON BY
THE ANCIENTS AND BY SEMI-CIVILIZED PEOPLE — UNIMPORTANT CHA-
RACTERS OFTEN ATTENDED TO— UNCON80IOU8 SELECTION — ^A8 CIRCUM-
STANCES SLOWLY CHANGE^ 80 HAVE OUR DOMESTICATED AlOMALS
CHANGED THROUGH THE ACTION OP UNCONSCIOUS SELECTION —
INFLUENCE OP BIFFKRKST BREEDERS ON THE SAME SUB-VARIETY —



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CONTENTS ix

PLANTS AS AFFBCTED BY UNCONSCIOUS SELBCTION — EryBCra OP
SELBCnON AS SHOWN BY THE GREAT AMOUNT OP DIPPERENCE IN
THE PARTS MOST VALUED BY MAN Pa§pM 210-258

CHAPTER XXI
SELECTION, continued

NATURAL SELECTION AS APPECTINO DOMESTIC PRODUCTIONS— CHARAC-
TERS WHICH APPEAR OP TRIPUNO VALUE OPTEN OP REAL IM-
PORTANCE — cmCUMBTANCES FAVOURABLE TO SELECTION BY MAN
— PAOIUTY IN PREVENTINO CROSSES, AND THE NATURE OP THE
CONDITIONS — CLOSE ATTENTION AND PERSEVERANCE INDUPENSABLB
— THE PRODUCTION OP A LAROE NUMBER OP INDIVIDUAUB ESPE-
CIALLY PAVOURABIJ] — 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 DIVEROENCB
OP CHARACTER, RARELY TO CONVERGENCE— CHARACTERS CONTINU-
ING TO VARY IN THE SAME DIRECTION IN WHICH THEY HAVE
ALREADY VARIED— DIVERGENCE OF CHARACTER, WITH THE EX-
TINCTION OP INTERMEDIATE VARIETIES, LEADS TO DISTINCTNESS IN
OUR DOMESTIC RACES — LIMIT TO THE POWER OF SELECTION — LAPSE
OP TIME IMPORTANT — MANNER IN WHICH DOMESTIC RACES HAVE
ORIGINATED — SUMMARY 250-292



CHAPTER XXn

CAUSES OF VARIABILITY

VARIABILrrY DOBS NOT NECESSARILY ACCOMPANY REPRODUCTION —
CAUSES ASSIGNED BY VARIOUS AUTHORS — INDIVIDUAL DIFFERENCES
— VARIABILITY OP EVERY KIND DUB TO CHANGED CONDITIONS OF
LIFE— ON THE NATURE OP SUCH CHANGES — CLIMATE, POOD, EXCESS
OP NUTRIMENT — BLIGHT CHANGES SUFFICIENT — EFFECTS OP GRAFT-
ING ON THE VARIABILITY OF SEEDLING-TREES — DOMESTIC PRO-
DUCTIONS BECOME HABITUATED TO CHANGED CONDITIONS— ON THE
ACCUMULATIVE ACTION OP CHANGED CONDITIONS — CLOSE INTER-
BREEDING AND THE IMAGINATION OF THE MOTHER SUPPOSED TO



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CONTENl'S

CAUSE VARIABILITY CR06SIN0 AS A CAUSE OF THE APPEARANCB

OF NEW CHARACTERS — VARIABIUTY FROM THE COMMINOLINO OP

CHARACTERS AND FROM REVERSION ON THE MANNER AND PERIOD

OF ACTION OF THE CAUSES WHICH EITHER DIRECTLY^ OR INDIRECTLY
THROUOH THE REPRODUCTIVE SYSTEM^ INDUCE VARIABILITY

Pages 293-320



CHAPTER XXIII

DIRECT AND DEFmiTE ACTION OF THE EXTERNAL
CONDITIONS OF UFE

SUOHT MODIFICATIONS IN PLANTS FROM THE DEFINITE ACTION OF
CHANGED CONDITIONS^ IN SIZE^ COLOUR^ CHEMICAL PROPERTIES^
AND IN THE STATE OF THE TISSUES — LOCAL DISEASES — CONSPICUOUS
MODIFICATIONS FROM CHANGED CLIMATE OR FOOD, ETC. — PLUMAGE
OF BIRDS AFFECTED BY PECULIAR NUTRIMENT, AND BY TH6
INOCULATION OF POISON— LAND-SHELLS — MODIFICATIONS OF ORGANIC
BEINGS IN A STATE OF NATURE THROUOH THE DEFINITE ACTION
OF EXTERNAL CONDITIONS — COMPARISON OF AMERICAN AND
EUROPEAN TREES GALLS — EFFECTS OF PARASITIC FUNGI — CON-
SIDERATIONS OPPOSED TO THE BELIEF IN THE POTENT INFLUENCE
OF CHANGED EXTERNAL CONDITIONS — PARALLEL SERIES OP
VARIETIES — AMOUNT OF VARIATION DOES NOT CORRESPOND WITH

THE DEGREE OF CHANGE IN THE CONDITIONS — BUD-VARIATION

MONSTROSITIES PRODUCED BY UNNATURAL TREATMENT — SUMMARY

321-350



CHAPTER XXIV

LAWS OF VARIATION USE AND DISUSE, ETC.

NISU8 FORMATIVUS, OR THE CO-ORDINATING POWER OF THE ORGANIZA-
TION—ON THE EFFECTS OF THE INCREASED USE AND DISUSE OP
ORGANS — CHANGED HABITS OF LIFE — ACCLIMATIZATION WITH
ANIMALS AND PLANTS — ^VARIOUS METHODS BY WHICH THIS CAN
BB EFFECTED — ARRESTS OF DEVELOPMENT — RUDIMENTARY ORGANS.

361-385



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CONTENTS xi

CHAPTER XXV

LAWS OF VAKIATION, COn^tflU^J— CORRELATED VARIABILITY

EXPLANATION OF TERM CORRELATION — CONNECTED WITH DEVELOPMENT
— MODIFICATIONS CORRELATED WITH THE INCREASED OR DECREASED
SIZE OF PARTS — CORRELATED VARIATION OF HOMOLOGOUS PARTR —
FEATHERED FEET IN RIRDS ASSUMING THE STRUCTURE OF THE
WINGS — CORRELATION BETWEEN THE HEAD AND THE BXTRBMITnBB —
BETWEEN THE SKIN AND DERMAL APPENDAGES — ^BETWEEN THE
ORGANS OF SIGHT AND HEARING— CORRELATED MODIFICATIONS Df
THE ORGANS OF PLANTS — CORRELATED M0N8TR0SITIBS — CORRE-
LATION BETWEEN THE SKULL AND EAR»— SKULL AND CREST OF
FEATHERS — SKULL AND HORNS— CORRELATION OF GROWTH COM-
PLICATED BT THE ACCUMULATED EFFMCl 'S OF NATURAL SELECTION
— COLOUR AS CORRELATED WITH CONSTITUTIONAL PECULIARITIEB

Pages 386-411

CHAPTER XXVI

LAWS OF VARIAT10K9 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 VARIATION —
ANALOGOUS OR PARALLEL VARIETIES — SUMMARY OF THE THREE
LAST CHAPTERS 412-431



CHAPTER XXVII

PROVISIONAL HYPOTHESIS OF PANGENESIS

PREUMINARY 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



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xii 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 THR
HYPOTHESIS OF THE SEVERAL CLASSES OF FACTS SPECIFIED IN THE
FIRST PART — CONCLUSION Pagcs 432-491



CHAPTER XXVIII

CONCLUDING REMARKS

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 PAR-
TICULAR VARIATION HAS BEEN SPECIALLY PREORDAINED 492-526



527



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THE

VARIATION OF ANIMALS AND PLANTS

UNDER DOMESTICATION



CHAPTER Xin

INHEBITAUCE COlUvnued — REVERSION OE 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 OP 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 inheritance to be discussed in this
chapter has been recognized by agriculturists and authors
of various nations, as shown by the scientific term Atavism
derived from atavus, an ancestor; by the English terms
of Reversion, or TTi^rottrntg-back ; by the French Pcu en-
Arrtire ; and by the German RUckschlag, or RUckschritt.
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

VOL. II. ^ B

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2 INHERITANCE [chap, xiii

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 dis-
plays some newly acquired and generally inheritable
character, and the offspring do not inherit it, the cause
may lie in the other parent having the power of pre-
potent transmission. But when both parents are similarly
characterized, and the child does not, whatever the cause
may be, inherit the character in question, but resembles its
grandparents, we have one of the simplest cases of rever-
sion. We continually see another and even more simple
case of atavism, though not genei'aJly included imder this
head, namely, when the son more closely resembles his
maternal than his paternal grandsire in some male attri-
bute, 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 attributes,
the child must inherit them, through her blood, from his
maternal grandsire.

The cases of reversion may 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



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CHAP, xiu] REVBBSIQN 8

instituted, to include leveniicms by segments in the sMEie
individual flower or fruit, and in difleroit parts of the
body in the same individual animal as it grows <dd. But
the two first main classes will be suffidoit for our purpose.

Reversion to lost Characters bjf ptire or uncrossed forms. —
Striking instances of this first class of cases were given in
the sixth chapter, namely, of the occasional rei^pearance,
in variously coloured l»eeds of the pigecm, of blue birds
with all the marks characteristic of the wild Cohimba fivto.
Similar cases were given in the case of the fowL With the
common ass, as the legs of the wild progenitor are almost
always striped, we may feel assured that the occasional
appearance 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
homs.^ 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 off.''^ The Galloways and Suffolk cattle
have been hornless for the last 100 or 150 years ; but a
'homed calf, with the horn often loosely attached, is
occasionally produced.'

There is reason to believe that sheep in their early
domesticated condition were " brown or dingy black *" ;
but even in the time of David certain flocks were spoken

* Youatt on Sheep, pp. ao^ 234. many ; Bechstein, ' Naturgesch.

The same fact of loose horns oc- Deutsch lands,' b. i. s. 36a.

casionally appearing in hornless ' Youatt on Cattle, pp. 155, 174.
breeds has beien observed in Ger-



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4 INHERITANCE [chap, xiii

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, parti-coloured
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, during 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 the reversion of crossed breeds, and likewise
on the subject of prepotency) that the Rev. 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 produced 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. Mr. Fox was also told
by the friend from whom the spotted breed was procured,
that he likewise had gone on for six or seven generations
crossing with white sheep, but still black lambs were
invariably produced.

» Youatt on Sbeep» 1838, pp. 17, Wilmot: 5##, also, remarks on this

145. subject in an article in the 'Quar-

* I have been informed of thb terly Review/ 1849, P« 395'

fact through the Rev. W. D. Fox, • Youatt, pp. 19, 284.
on the excellent authority of Mr.



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CHAP, xm] REVERSION 6

Similar &ct8 could be given with respect to taillefls
breeds 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 considerable nmnber of instances
were fiimished 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
kingdom ; 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 produced ; ^ ^ but the reversion in this instance
is not to a very ancient period, for the best exist-
ing varieties of the heartsease are of comparatively
modem origin. With most of our cultivated vege-
tables there is some tendency to reversion to what
is known to be, or may be presumed to be, their



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