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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 ; the Tartars prefer them with
Bpirally wound horns, because the hornless are thought to
lose courage.^^ Some of the Damaras will not eat the flesh
of hornless sheep. In regard to horses, at the end of the
fifteenth centur^^ animals of the colour described as Hart
pomme were most valued in France. Ihe Arabs have a
proverb, " Kever buy a horse with four white feet, for he
carries his shroud with him ; "^^ the Arabs also, as we have
8^en, despise dun-coloured horses. So with dogs, Xenophon
and others at an ancient period were prejudiced in favour of
certain colours ; and " white or slate-coloured hunting dogs
were not esteemed." ^^

Turning to poultry, the old Eoman gourmands thought
that the liver of a white goose was the most savoury. In
Paraguay black-skinned fowls are kept because they are
thought to be more productive, and their flesh the most proper
for invalids.^** In Guiana, as 1 am informed by Sir R. Schom-
burgk, the aborigines will not eat the flesh or eggs of the
fowl, but two races are kept distinct merely for ornament.
In the Philippines, no less than nine sub-varieties of the game-
cock are kept and named, so that they must be separately
bred.

At the present time in Europe, the smallest peculiarities
are carefully attended to in our most useful animals, either
from fashion, or as a mark of purity of blood. Many examples
could be given ; two will suffice. " In the Western counties
*' of England the prejudice against a white pig is nearly as
" strong as against a black one in Yorkshire." In one of the

«* Livingstone's Travels, p. 576 ; «« F. Michel, ' Des Haras,' pp. 47,

Andersson, 'Lake Ngaiiii,' 1856, p. 50.

222. With respect to the sale in *^ Col. Hamilton Smith, Dogs, in

Kaffraria, see ' Quarterly Review,' * Nat. Lib.,' vol. x. p. 103.

1860, p. 139. ^^ Azara, ' Quadrupfedes du Para-

" ' Memoiresur les Chinois'(by the guay,' torn, ii, p. 324.
Jesuits), J 786, torn. xi. p. 57.

Chap. XX. UNCONSCIOUS SELECTION. 195

Berkshire sub-breeds, it is said, " the white should be confined
" to four white feet, a white spot between the eyes, and a few
" white hairs behind each shoulder." Mr. Saddler possessed
" three hundred pigs, every one of which was marked in this
*' manner." ^^ Marshall, towards the close of the last century,
in speaking of a change in one of the Yorkshire breeds of
cattle, says the horns have been considerably modified, as
'* a clean, small, sharp horn has been fashionable for the last
twenty years." '° In a part of Germany the cattle of the
Eace de Gfoehl are valued for many good qualities, but they
must have horns of a particular curvature and tint, so much
so that mechanical means are applied if they take a wrong
direction ; but the inhabitants " consider it of the highest
*' importance that the nostrils of the bull should be flesh-
-coloured, and the eyelashes light; this is an indispensable
" condition. A calf with blue nostrils would not be pur-
" chased, or purchased at a very low price." "^ Therefore let
no man say that any point or character is too trifling to be
methodically attended to and selected by breeders.

Unconscious Selection. — By this term I mean, as already more
than once explained, the preservation by man of the most
valued, and the destruction of the least valued individuals,
without any conscious intention on his part of altering the
breed. It is difficult to offer direct proofs of the results
which follow from this kind of selection ; but the indirect
evidence is abundant. In fact, except that in the one case
man acts intentionally, and in the other unintentionally,
there is little difierence between methodical aad unconscious
selection. In both cases man preserves the animals which
are most useful or pleasing to him, and destroys or neglects
the others. But no doubt a far more rapid result follows from
methodical than from unconscious selection. The " roguing "
of plants by gardeners, and the destruction by law in Henry
VIII.'s reign of all under-sized mares, are instances of a
process the reverse of selection in the ordinary sense of the

«9 Sidney's edit, of Youatt, 1860, vol. ii. p. 182.
pp. 24, 25. " Moll et Gayot, ' Du Bceuf,' 1860

'" * Rural Economy of Yorkshire,' p. 547.

196 SELECTION. Chap. XX.

word, but leading to tlie same general result. The influence
of the destruction of individuals having a particular character
is well shown by the necessity of killing every lamb with a
trace of black about it, in order to keep the flock white ; or
again, by the effects on the average height of the men of
France of the destructive wars of Napoleon, by which many
tall men were killed, the short ones being left to be the
fathers of families. This at least is the conclusion of some of
those who have closely studied the effects of the conscription;
and it is certain that since Napoleon's time the standard for
the armv has been lowered two or three times.

Unconscious selection blends with methodical, so that it is
scarcely possible to separate them. When a fancier long ago
first happened to notice a pigeon with an unusually short
beak, or one with the tail-feathers unusually developed,
although he bred from these birds with the distinct intention
of propagating the variety, yet he could not have intended to
make a short-faced tumbler or a fantail, and was far from know-
ing that he had made the first step towards this end. If he
could have seen the final result, he would have been struck
with astonishment, but, from what we know of the habits of
fanciers, probably not with admiration. Our English carriers,
barbs, and short-faced tumblers have been greatly modified in
the same manner, as we may infer both from the historical
evidence given in the chapters on the Pigeon, and from the
comparison of birds brought from distant countries.

■So it has been with dogs; our present fox-hounds differ
from the old English hound; our greyhounds have become
lighter : the Scotch deer-hound has been m odified, and is now
rare. Our bulldogs differ from those which were formerly
used for baiting bulls. Our pointers and Newfoundlands do
not closely resemble any native dog now found in the countries
whence they were brought. These changes have been effected
partly by crosses ; but in every case the result has been
governed by the strictest selection. Nevertheless, there is no
reason to suppose that man intentionally and methodicall}'
made the breeds exactly what they now are. As our horses
became fleeter, and the country more cultivated and smoothei",
fleeter fox-hounds were desired and produced, but probaLl;y

Chap. XX. UNCONSCIOUS SELECTION. 197

without any one distinctly foreseeing what they would become.
Our pointers and setters, the latter almost certainly descended
from large spaniels, have been greatly modified in accordance
with fashion and the desire for increased speed. Wolves have
become extinct, and so has the wolf-dog ; deer have become
rarer, bulls are no longer baited, and the corresponding breeds
of the dog have answered to the change. But we may feel
almost sure that when, for instance, bulls M^ere no longer
baited, no man said to himself, I will now breed my dogs of
smaller size, and thus create the present race. As circum-
stances changed, men unconsciously and slowly modified their
course of selection.

With race-horses selection for swiftness has been followed
methodically, and our horses now easily surpass their pro-
genitors. The increased size and different appearance of the
English race-horse led a good observer in India to ask, " Could
any one in this year of 1856, looking at our race-horses,
conceive that they were the result of the union of the Arab
horse and the African mare ? " '^^ This change has, it is
probable, been largely effected through unconscious selection,
that is, by the general wish to breed as fine horses as possible
in each generation, combined with training and high feeding,
but without any intention to give to them their present
appearance. According to Youatt,'^^ the introduction in Oliver
Cromwell's time of three celebrated Eastern stallions speedily
affected the English breed ; "so that Lord Harleigh, one of
the old school, complained that the great horse was fast dis-
appearing." This is an excellent proof how carefully selection
must have been attended to ; for without such care, all traces
of so small an infusion of Eastern blood would soon have been
absorbed and lost. Notwithstanding that the climate of
England has never been esteemed particularly favourable to
the horse, yet long-continued selection, both methodical and
unconscious, together with that practised b}^ the Arabs during
a still longer and earlier period, has ended in giving us the
best breed of horses in the world. Macaulay ^* remarks,

"2 ' The India Sporting Review,' " ' The Horse,' p. 22.

vol. ii. p. 181; 'The Stud Farm/ by ^* 'History of England,' vol. i. p,

Cecil, p. 58. 316.

198 SELECTION. Chap. XX.

((

Two men whose authority on such subjects was held in
*' great esteem, the Duke of Newcastle and Sir John Fenwick,
*' pronounced that the meanest hack ever imported from
" Tangier would produce a finer progeny thau could be
*' expected from the best sire of our native breed. They
" would not readily have believed that a time would come
" when the princes and nobles of neighbouring lands would
" be as eager to obtain horses from England as ever the
" English had been to obtain horses from Barbary."

The London dray-horse, which differs so much in appear-
ance from any natural species, and which from its size has so
astonished many Eastern princes, was probably formed by the
heaviest and most powerful animals having been selected
during many generations in Flanders and England, but
without the least intention or expectation of creating a horse
such as we now see. If we go back to an early period of
history, we behold in the antique Greek statues, as Schaaff-
hausen has remarked, '^^ a horse equally unlike a race or dray
horse, and differing from any existing breed.

The results of unconscious selection, in an early stage, are
well shown in the diiference between the flocks descended
from the same stock, but separately reared by careful breeders.
Youatt gives an excellent instance of this fact in the sheep
belonging to Messrs. Buckley and Burgess, which " have been
" purely bred from the original stock of Mr. Bake well for
*' upwards of fifty years. There is not a suspicion existing in
" the mind of any one at all acquainted with the subject that
" the owner of either flock has deviated in any one instance
*' from the pure blood of Mr. Bakewell's flock ; yet the differ-
*' ence between the sheep possessed by these two gentlemen is
" so great, that they have the appearance of being quite
" different varieties." ^^ I have seen several analos^ous and
well marked cases with pigeons : for instance, I had a family
of barbs descended from those long bred by Sir J. Sebright,
and another family long bred by another fancier, and the two
families plainly differed from each other. Xathusius — and a
more competent witness could not be cited — observes that,
though the Shorthorns are remarkably uniform in appearance
^^ ' Ueber Besfandigkeit der Arten. '^ Youatt on Sheep, p. 315.

Chap. XX. UNCONSCIOUS SELECTION. 199

(except in colour), yet the individual character and wishes of
each breeder become impressed on his cattle, so that different
herds differ slightly from one another.'^'^ The Hereford cattle
assumed their present well-marked character soon after the
year 1769, through careful selection by Mr. Tomkins,'^^ and
the breed has lately split into two strains — one strain having
a white face, and differing slightly, it is said,'^^ in some other
points : but there is no reason to believe that this split, the
origin of which is unknown, was intentionally made ; it
may with much more probability be attributed to different
breeders having attended to different points. So again, the
Berkshire breed of swine in the year 1810 had greatly changed
from what it was in 1780; and since 1810 at least two
distinct sub-breeds have arisen bearing the same name.^®
Keeping in mind how rapidly all animals increase, and that
some must be annually slaughtered and some saved for
breeding, then, if the same breeder during a long course of
years deliberately settles which shall be saved and which
shall be killed, it is almost inevitable that his individual
turn of mind will influence the character of his stock,
without his having had any intention to modify the breed.

Unconscious selection in the strictest sense of the word,
that is, the saving of the more useful animals and the neglect
or slaughter of the less useful, without any thought of the
future, must have gone on occasionally from the remotest
period and amongst the most barbarous nations. Savages
often suffer from famines, and are sometimes expelled by war
from their own homes. In such cases it can hardly be doubted
that they would save their most useful animals. When the
Fuegians are hard pressed by want, they kill their old women
for food rather than their dogs ; for, as we were assured,
" old women no use — dogs catch otters." The same sound
sense would surely lead them to preserve their more useful
dogs when still harder pressed by famine. Mr. Oldfield, who
has seen so much of the aborigines of Australia, informs me

" 'Ueber Shcrthoru Rindvieh,' '^ 'Quarterly Review,' 1849, p.

1857, s. 51, 392.

'* Low, ' Domestkated Animals,' ** H. von Nathusins, 'Vorstudien

1845, p. 363. .... Schweineschjidel,' 1864, s. 140.

200 SELECTION. Chap. XX.

that " they are all very glad to get a European kangaroo dog,
and several instances have been known of the father killing
his own infant that the mother might suckle the much-prized
puppy." Diiferent kinds of dogs would be useful to the
Australian for hunting opossums and kangaroos, and to the
Fuegian for catching fish and otters ; and the occasional
preservation in the two countries of the most useful animals
would ultimately lead to the formation of two widely distinct
breeds.

With plants, from the earliest dawn of civilisation, the best
variety which was known would generally have been cultivated
at each period and its seeds occasionally sown ; so that there
will have been some selection from an extremely remote
peiiod, but without any prefixed standard of excellence or
thought of the future. AVe at the present day profit by a
course of selection occasionally and unconsciously carried on
during thousands of years. This is proved in an interesting
manner by Oswald Heer's researches on the lake-inhabitants
of Switzerland, as given in a former chapter ; for he shows
that the grain and seed of our present varieties of w^heat,
barley, oats, peas, beans, lentils, and poppy, exceed in size
those which were cultivated in Switzerland during the
Neolithic and Bronze periods. These ancient people, during
the Neolithic period, possessed also a crab considerably larger
than that now growing wild on the Jura.^^ The pears described
by Pliny were evidently extremely inferior in quality to our
present pears. We can realise the effects of long-continued
selection and cultivation in another way, for would any one
in his senses expect to raise a first-rate apple from the seed of
a truly wild crab, or a luscious melting pear from the wild
pear? Alphonse de Candolle informs me that he has lately
seen on an ancient mosaic at Rome a representation of the
melon ; and as the Eomans, who were such gourmands, are
silent on this fruit, he infers that the melon has been greatly
ameliorated since the classical period.

Coming to later times, Buffon,*- on comparing the flowers,

*i See also Dr. Christ, in Riiti- ^^ The passage is given, ' Bull. Soc

mcyer's * Pfahlbauten,' 1861, s. 226. d'AocIimat.,' 1358, p. 11.

Chap. XX. UNCONSCIOUS SELECTION. 201

fruit, and vegetables which were then cultivated with some
excellent drawings made a hundred and fifty years previously,
was struck with surprise at the great improvement which had
been effected ; and remarks that these ancient flowers and
vegetables would now be rejected, not only by a florist but by
a village gardener. Since the time of Buffon the work of
improvement has steadil}^ and rapidly gone on. Every florist
who compares our present flowers with those figured in books
published not long since, is astonished at the change. A well-
known amateur,^^ in speaking of the varieties of Pelargonium
raised by Mr. Garth only twenty-two years before, remarks,
" What a rage they excited : surely we had attained perfection,
*' it was said; and now not one of the flowers of those days
" will be looked at. But none the less is the debt of gratitude
*' which we owe to those who saw what was to be done, and
*' did it." Mr. Paul, the well-known horticulturist, in writing
of the same flower,^* says he remembers when young being
delighted with the portraits in Sweet's work ; " but what are
'* they in point of beauty compared with the Pelargoniums of
" this day ? Here again nature did not advance by leaps ;
" the improvement was gradual, and if we had neglected
" those very gradual advances, we must have foregone the
" present grand results." How well this practical horti-
culturist appreciates and illustrates the gradual and accumu-
lative force of selection ! The Dahlia has advanced in beauty
in a like manner ; the line of improvement being guided by
fashion, and by the sucessive modifications which the flower
slowly underwent.**^ A steady and gradual change has been
noticed in many other flowers : thus an old florist,^^ after
describing the leading varieties of the Pink which were
grown in 1813, adds, '* the pinks of those days would now be
" scarcely grown as border-flowers." The improvement of
so many flowers and the number of the varieties which have
been raised is all the more striking when we hear that the

"^ * Journal of Horticulture,' 1862, Floricult. See, in * Gardener's Chro-

p. 394. nicle,' 18+3, p. 86.

** 'Gardener's Chronicle,' 1857, *« ' Journal of Horticulture,* Oct.

p. 85. 24th, 18G5, p. 239.

*^ See Mr. Wildman's address to the

202 SELECTION. Chap. XX.

earliest known flower-garden in Europe, namely at Padua,
dates only from the year 1545.^^

Effects of Selection, as shown by the parts most valued by man
presenting the greatest amount of difference. — The power of long-
continued selection, whether methodical or unconscious, or
both combined, is well shown in a general way, namely, by
the comparison of the differences between the varieties of dis-
tinct species, which are valued for different parts, such as for
the leaves, or stems, or tubers, the seed, or fruit, or flowers.
Whatever part man values most, that part will be found to
present the greatest amount of difference. AVith trees culti-
vated for their fruit, Sageret remarks that the fruit is larger
than in the parent-species, whilst with those cultivated for
the seed, as with nuts, walnuts, almonds, chestnuts, &c., it is
the seed itself which is larger ; and he accounts for this fact
by the fruit in the one case, and by the seed in the other,
having been carefully attended to and selected during many
ages. Gallesio has made the same observation. Godron
insists on the diversity of the tuber in the potato, of the bulb
in the onion, and of the fruit in the melon ; and on the close
similarity of the other parts in these same plants.^'*

In order to judge how far my own impression on this
subject was correct, I cultivated numerous varieties of the
same species close to one another. 1'lie comparison of the
amount of difference between widely different organs is neces-
sarily vague ; I will therefore give the results in only a few
cases. We have previously seen in the ninth chapter how
greatly the varieties of the cabbage differ in their foliage and
stems, which are the selected parts, and how closely they re-
semble one another in their flowers, capsules, and seeds. In
seven varieties of the radish, the roots differed greatly in
colour and shape, but no difference whatever could be detected
in their foliage, flowers, or seeds. Now what a contrast is

*'^ Prescott's ' Hist, of Mexico,' vol. eleventh chapters I have given details

ii. p. 61. on the potato ; and I can confirm

*^ Sagaret, ' Pomologie Physiolo- similar remarks with respect to the

gique,' 1830, p. 47 ; Gallesio, ' Teoria onion. I have also shown how far

della Ripi-oduzione,' 1816, p. 88 ; Kaudin concurs in regard to the

Godron, ' De I'Espfece,' 1859, torn. ii. varieties of the melon.
pp. 63, 67, 70. In my tenth and

Chap. XX. SELECTION. 203

presented, if we compare the flowers of the varieties of these
two plants with those of any species cultivated in our flower-
gardens for ornament ; or if we compare their seeds with
those of the varieties of maize, peas, beans, &c., which are
valued and cultivated for their seeds. In the ninth chapter
it was shown that the varieties of the pea differ but little
except in the tallness of the plant, moderately in the shape of
the pod, and greatly in the pea itself, and these are all selected
j)oints. The varieties, however, of the Pois sans parchemin
difier much more in their pods, and these are eaten and valued.
I cultivated twelve varieties of the common bean ; one alone,
the Dwarf Fan, differed considerably in general appearance ;
two differed in the colour of their flowers, one being an albino,
and the other being wholly instead of partially purple ; several
differed considerably in the shape and size of the pod, but far
more in the bean itself, and this is the valued and selected part.
Toker's bean, for instance, is twice-and-a-half as long and
broad as the horse-bean, and is much thinner and of a different
shape.

The varieties of the gooseberr}^, as formerly described, differ
much in their fruit, but hardly perceptibly in their flowers or
organs of vegetation. With the plum, the differences likewise
appear to be greater in the fruit than in the flowers or leaves.
On the other hand, the seed of the strawberry, which corre-
sponds with the fruit of the plum, differs hardly at all ; whilst
every one knows how greatly the fruit — that is, the enlarged
receptacle — differs in several varieties. In apples, pears,
and peaches the flowers and leaves differ considerably, but not,
as far as I can judge, in proportion with the fruit. The
Chinese double- flowering peaches, on the other hand, show
that varieties of this tree have been formed, which differ
more in flower than in fruit. If, as is highly probable, the
peach is the modified descent of the almond, a surprising
amount of change has been effected in the same species,
in the fleshy covering of the former and in the kernels of the
latter.

When parts stand in close relationship to each other, such
as the seed and the fleshy covering of the fruit (v/hatever
its homological nature may be), changes in the one are

204 SELECTION. Chap. XX.

usually accompanied by modifications in the other, though
not necessarily to the same degree. With the plum-tree,
for instance, some varieties produce plums which are nearly
alike, but include stones extremely dissimilar in shape;
whilst conversely other varieties produce dissimilar fruit
with barely distinguishable stones ; and generally the stones,
though they have never been subjected to selection, differ
greatly in the several varieties of the plum. In other
cases organs which are not manifestly related, through
some unknown bond vary together, and are consequently
liable, without any intention on man's part, to be simul-
taneously acted on by selection. Thus the varieties of the
stock (Matthiola) have been selected solely for the beauty of
their flowers, but the seeds differ greatly in colour and some-
what in size. Varieties of the lettuce have been selected solely
on account of their leaves, yet produce seeds which likewise
differ in colour. Generally, through the law of correlation,
when a variety differs greatly from its fellow- varieties in any
one character, it differs to a certain extent in several other
characters. I observed this fact when I cultivated together
many varieties of the same species, for I used first to make a list
of the varieties which differed most from each other in their
foliage and manner of growth, afterwards of those that differed
most in their flowers, then in their seed-capsules, and lastly
in their mature seed ; and I found that the same names gene-
rally occurred in two, three, or four of the successive lists.
Nevertheless the greatest amount of difference between the
varieties was always exhibited, as far as I could judge, by
that part or organ for which the plant was cultivated.

When we bear in mind that each plant was at first culti-
vated because useful to man, and that its variation was a
subsequent, often a long subsequent, event, we cannot explain
the greater amount of diversity in the valuable parts by
siij^posing that species endowed with an especial tendency to
vary in any particular manner were originally chosen. We
must attribute the result to the variations in these parts
having been successively preserved, and thus continually
augmented; whilst other variations, excepting such as in-
evitably appeared through correlation, were neglected and

Chap. XX. SELECTION. 205

lost. We may therefore infer tliat most plants might be
made, through long-continued selection, to yield races as
different from one another in any character as they now are
in those parts for which they are valued and cultivated.

AVith animals we see nothing of the same kind; but a
sufficient number of species have not been domesticated for a
fair comparison. Sheep are valued for their wool, and the
wool differs much more in the several races than the hair in
cattle. Neither sheep, goats, European cattle, nor pigs are
valued for their fleetness or strength ; and we do not possess
breeds differing in these respects like the race-horse and dray-
horse. But fleetness and strength are valued in camels and
dogs ; and we have with the former the swift dromedary and
heavy camel; with the latter the greyhound and mastiff".
But dogs are valued even in a higher degree for their mental
qualities and senses ; and every one knows how greatly
the races differ in these respects. On the other hand, where
the dog is kept solely to serve for food, as in the Polynesian
islands and China, it is described as an extremely stupid
animal.^^ Blumenbach remarks that " many dogs, such as
*' the badger-dog, have a build so marked and so appropriate
" for particular purposes, that I should find it very difficult
" to persuade mj'self that this astonishing figure was an
" accidental consequence of degeneration." ^" Had Blumen-
bach reflected on the great principle of selection, he would not
have used the term degeneration, and he would not have been
astonished that dogs and other animals should liecome excel-
lently adapted for the service of man.

On the whole we may conclude that whatever part or
character is most valued — whether the leaves, stems, tubers,
bulbs, flowers, fruit, or seed of plants, or the size, strength,
fleetness, hairy covering, or intellect of animals — that cha-
racter will almost invariably be found to present the greatest
amount of difference both in kind and degree. And this
result may be safely attributed to man having preserved
during a long course of generations the variations which
were useful to him, and neglected the others.

•' Godron, -De I'Espece,' torn. ii. ^° 'The Anthropological Treatises

p. 27. of Blumenbach/ 1856, p. 292.

31

206 SELECTION. Ckap. XX.

I will conclude this chapter by some remaiks on an im-
portant subject. With animals such as the giraffe, of which
the whole structure is admirabl}^ co-ordinated for certain pur-
poses, it has been supposed that all the parts must have been
simultaneously modified ; and it has been argued that, on the
principle of natural selection, this is scarcely possible. But in
thus arguing, it has been tacitly assumed that the variations
must have been abrupt and great. No doubt, if the neck
of a ruminant were suddenly to become greatly elongated,
the fore limbs and back would have to be simultaneously
strengthened and modified ; but it cannot be denied that an
animal might have its neck, or head, or tongue, or fore-limbs
elongated a very little without any corresponding modifica-
tion in other parts of the body ; and animals thus slightly
modified would, during a dearth, have a slight advantage,
and be enabled to browse on higher twigs, and thus survive.
A few mouth fuls more or less every day would make all the
difference between life and death. By the repetition of the
same process, and by the occasional intercrossing of the sur-
vivors, there would be some progress, slow and fluctuating
though it would be, towards the admirably co-ordinated
structure of the giraffe. If the short-faced tumbler-pigeon,
with its small conical beak, globular head, rounded body,
short wings, and small feet — characters which appear all in
harmony — had been a natural species, its whole structure
would have been viewed as well fitted for its life ; but in this
case we know that inexperienced breeders are urged to attend
to point after point, and not to attempt improving the whole
structure at the same time. Look at the greyhound, that
perfect image of grace, symmetry, and vigour; no naturf^l
species can boast of a more admirably co-ordinated structure,
with its tapering head, slim body, deep chest, tucked-up
abdomen, rat-like tail, and long muscular limbs, all adapted
for extreme fleetness, and for running down weak prey.
Now, fiom what we see of the variability of animals, and
f 1 om what we know of the method which different men follow
in improving their stock — some chiefly attending to one
point, others to another point, others again correcting defects
by crosses, and so forth — we may feel assured that if we

Chap. XX. SELECTION. 207

could see the long line of ancestors of a first- rate greyhound
up to its wild wolf-like progenitor, we should behold an
infinite number of the finest gradations, sometimes in one
character and sometimes in another, but all leading towards
our present perfect type. By small and doubtful steps such
as these, nature, as we may confidently believe, has progressed,
on her grand march of improvement and development.

A similar line of reasoning is as applicable to separate
organs as to the whole organisation. A writer^^ has recently
maintained that " it is probably no exaggeration to suppose
*' that in order to improve such an organ as the eye at all,
" it must be improved in ten different ways at once. And
" the improbability of any complex organ being produced
" and brought to perfection in any such way is an im-
" probability of the same kind and degree as that of producing
" a poem or a mathematical demonstration by throwing
" letters at random on a table." If the eye were abruptly
and greatly modified, no doubt many parts would have to be
simultaneously altered, in order that the organ should remain
serviceable.

But is this the case with smaller changes ? There are
persons who can see distinctly only in a dull light, and this
condition depends, I believe, on the abnormal sensitiveness of
the retina, and is known to be inherited. Now if a bird, for
instance, receive some great advantage from seeing well in
the twilight, all the individuals with the most sensitive
retina would succeed best and be the most likely to survive ;
and why should not all those which happened to have the eye
itself a little larger, or the pupil capable of greater dilatation,
be likewise preserved, whether or not these modifications
were strictly simultaneous? These individuals would sub-
sequently intercross and blend their respective advantages.
By such slight successive changes, the eye of a diurnal bird
would be brought into the condition of that of an owl, which

^' Mr. J. J. Murphy, in his opening cautiously given by the Rev. C.

address to the Beltast Nat. Hist. Soc., Pritchard, Pres. Royal Astronomical

as given in the ' Belfast Northern Soc, in his sermon (Appendix, p. 33)

Whig,' Nov. 19, 1866. Mr. Murphy preached before the British Associa-

here follows the line of argument tion at Nottingham, 1866.
against my views previously and more

208 SELECTION. Chap. XX.

Has often been advanced as an excellent instance of adapta-
tion. Short-sight, which is often inherited, permits a person
to see distinctly a minute object at so near a distance that it
would be indistinct to ordinary eyes ; and here we have a
capacity which might be serviceable under certain conditions,
abruptly gained. The Fuegians on board the Beagle could
certainly see distant objects more distinctly than our sailors
with all their long practi'ce; I do not know whether this
depends upon sensitiveness or on the power of adjustment in
the focus ; but this capacity for distant vision might, it is
probable, be slightly augmented by successive modifications
of either kind. Amphibious animals which are enabled to
see both in the water and in the air, require and possess, as
M. Plateau has shown,^^ eyes constructed on the following
plan : " the cornea is always flat, or at least much flattened
" in the front of the crystalline and over a sj)ace equal to the
" diameter of that lens, whilst the lateral portions may be
" much curved." The crystalline is very nearly a sphere, and
the humours have nearly the same density as water. Now
as a terrestrial animal became more and more aquatic in its
habits, very slight changes, first in the curvature of the
cornea or crystalline, and then in the density of the humours,
or conversely, might successively occur, and would be advan-
tageous to the animal whilst under water, without serious
detriment to its power of vision in the air. It is of course
impossible to conjecture by what steps the fundamental
structure of the eye in the Vertebrata was originally acquired,
for we know nothing about this organ in the first progenitors
of the class. With respect to the lowest animals in the scale,
the transitional states through which the eye at first probably
passed, can by the aid of analogy be indicated, as I have
attempted to show in my ' Origin of Species.' ^^

92 On the Vision of Fishes and p. 469.
Amphibia, translated in 'Annals and ^^ Sisth edition, 1872, p. 144.

Mag. of Nat. Hist.,' vol. xviii., 1866,

Chap. XXI. NATUKAL SELECTION. 209

CHAPTEK XXI.

SELECTION, continued.

NATURAL SELECTION AS AFFECTING DOMESTIC PRODLCTIONS CHARACTERS

WHICH APPEAR OP TRIFLING VALUE OFTEN OF REAL IMPORTANCE —

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 ESPECIALLY FAVOURABLE — WHEN NO
SELECTION IS APPLIED, DISTINCT RACES ARE NOT FORMED — HIGHLY-BRED
ANIMALS LIABLE TO DEGENERATION — TENDENCY IN BIAN TO CARRY THE
SELECTION OF EACH CHARACTER TO AN EXTREME POINT, LEADING TO
DIVERGENCE OF CHARACTER, RARELY TO CONVERGENCE — CHARACTEliS
CONTINUING TO VARY IN THE SAME DIRECTION IN WHICH THEY HAVE
ALREADY VARIED — DIVERGENCE OF CHARACTER, WITH THE EXTINCTION
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.

Natural Selection, or tlie Survival of the Fittest, as affecting
domestic productions. — We know little on this head. But as
animals kept by savages have to provide throughout the year
their own food either entirely or to a large extent, it can
hardly be doubted that in different countries, varieties dif-
fering in constitution and in various characters would
succeed best, and so be naturally selected. Hence perhaps it
is that the few domesticated animals kept by savages partake,
as has been remarked by more than one writer, of the wild
appearance of their masters, and likewise resemble natural
species. Even in long-civilised countries, at least in the
wilder parts, natural selection must act on our domestic races.
It is obvious that varieties having very different habits, consti-
tution, and structure, would succeed best on mountains and
on rich lowland pastures. For example, the improved Lei-
cester sheep were formerly taken to the Lammermuir Hills ;
but an intelligent sheep-master reported that " our coarso
" lean pastures were unequal to the task of supporting such
" heavy-bodied sheep ; and they gradually dwindled away
" into less and less bulk : each generation was inferior to the

210 SELECTION. Chap. XXI

" preceding one ; and wlien the spring was severe, seldom
" more than two-thirds of the lambs survived the ravages of
" the storms." ^ So with the mountain cattle of North Wales
and the Hebrides, it has been found that they could not
withstand being crossed with the larger and more delicate
lowland breeds. Two French naturalists, in' describing the
horses of Circassia, remark that, subjected as they are to
extreme vicissitudes of climate, having to search for scanty
pasture, and exposed to constant danger from wolves, the
strongest and most vigorous alone survive.^

Every one must have been struck with the surpassing
grace, strength, and vigour of the Game-cock, with its bold
and confident air, its long, jet firm neck, compact body,
powerful and closely pressed wings, muscular thighs, strong
beak massive at the base, dense and sharp spurs set low on
tVie legs for delivering the fatal blow, and its compact, glossy,
and mail-like plumage serving as a defence. Now the En-
glish game-cock has not only been improved during many
years by man's careful selection, but in addition, as Mr.
Tegetmeier has remarked,^ by a kind of natural selection, for
the strongest, most active and courageous birds have stricken
down their antagonists in the cockpit, generation after gene-
ration, and have subsequently served as the progenitors of
their race. The same kind of double selection has come into
j)lay with the carrier pigeon, for during tlieir training the
inferior birds fail to return home and are lost, so that even
without selection by man only the superior birds propagate
their race.

In Great Britain, in former times, almost everv district
had its own breed of cattle and sheep ; " they were indigenous
" to the soil, climate, and pasturage of the locality on which
" they grazed : they seemed to have been formed for it and
" by it." * But in this case we are quite unable to disentangle
the effects of the direct action of the conditions of life, — of
use or habit — of natural selection — and of that kind of

* Quoted bv Youatt on Sheep, p. viii., 1861, p. 311.

325. See also Youatt on Cattle, pp. ^ t^he Poultry Book,' 1866, p. 123.

62, 69. Mr. Tegetmeier, 'The Homing orCar-

2 MM. Lherbette and De Quatre- rier Pigeon,' 1871, pp. 45-58.

fages, in * Bull. Soc. d'Acclimat.,' trm. * Youatt on Sheep, p. 312.

Chap. XXI. NAT ORAL SELECTION. 211

selection which we have seen is occasionally and uncon-
sciously followed by man even during the rudest periods of
histor}'-.

Let us now look to the action of natural selection on special
characters. Although nature is difficult to resist, yet man
often strives against her power, and sometimes with success.
From the facts to be given, it will also be seen that natural
selection would powerfully affect many of our domestic pro-
ductions if left unprotected. This is a point of much interest,
for we thus learn that differences apparently of very slight
importance would certainly determine the survival of a form
jvhen forced to struggle for its own existence. It may have
occurred to some naturalists, as it formerly did to me, that,
though selection acting under natural conditions would
determine the structure of all important organs, yet that it
could not affect characters which are esteemed by us of little
importa,nce ; but this is an error to which we are eminently
liable, from our ignorance of what characters are of real value
to each living creature.

When man attempts to make a breed with some serious
defect in structure, or in the mutual relation of the several
parts, he will partly or completely fail, or encounter much
difficulty ; he is in fact resisted by a form of natural selection.
We have seen that an attempt was once made in Yorkshire
to breed cattle with enormous buttocks, but the cows perished
so often in bringing forth their calves, that the attempt had
to be given up. In rearing short-faced tumblers, Mr. Eaton
says,^ " I am convinced that better head and beak birds have
*' perished in the shell than ever were hatched ; the reason
" being that the amazingly short-faced bird cannot reach and
*' break the shell with its beak, and so perishes." Here is
a more curious case, in which natural selection comes into
play only at long intervals of time : during ordinary seasons
the Xiata cattle can graze as well as others, but occasionally,
as from 1827 to 1830, the plains of La Plata suffer from long-
continued droughts and the pasture is burnt up ; at such
times common cattle and horses perish by the thousand, but
many survive by browsing on twigs, reeds, &c. ; this the
* ' Treatise on the Almond Tumbler,' 1851, p. 33.

212 SELECTION. Chap. XXI.

Niata cattle cannot so well effect from their upturned jaws
and the shape of their lips ; consequently, if not attended to,
the}' perish before the other cattle. In Columbia, according
to Eoulin, there is a breed of nearly hairless cattle, called
Pelones ; these succeed in their native hot district, but are
found too tender for the Cordillera ; in this case, however,
natural selection determines only the range of the variety.
It is obvious that a host of artificial races could never survive
in a state of nature ; — such as Italian greyhounds, — hairless
and almost toothless Turkish dogs, — fantail pigeons, which
cannot fly well against a strong wind, — barbs and Polish
fowls, with their vision impeded by their eje wattles and
great topknots, — hornless bulls and rams, which consequently
cannot cope with other males, and thus have a poor chance
of leaving offspring, — seedless plants, and many other such
cases.

Colour is generally esteemed by the systematic naturalist
as unimportant : let us, therefore, see how far it indirectly
affects our domestic productions, and how far it would affect
them if they were left exposed to the full force of natural
selection. In a future chapter I shall have to show that con-
stitutional peculiarities of the strangest kind, entailing
liability to the action of certain poisons, are correlated with
the colour of the skin. I will here give a single case, on the
high authority of Professor Wyman ; he informs me that,
being surprised at all the pigs in a part of Virginia being
black, he made inquiries, and ascertained that these animals
feed on the roots of the Lachnanthes tinctoria, which colours
their bones pink, and, excepting in the case of the black
varieties, causes the hoofs to drop off. Hence, as one of the
squatters remarked, " we select the black members of the
litter for raising, as they alone have a good chance of living."
So that here we have artificial and natural selection work-
ing hand in hand. I may add that in the Tarentino tli«
Inhabitants keep black sheep alone, because the Hypericum
crinpum abounds there ; and this plant does not injure black
sheep, but kills the white ones in about a fortnight's tinie.^

Complexion, and liability to certain diseases, are believed

• Dr. Heusinger, ' Woch-iuschrift fiir die Heilkunde,' Berlin, 1840, s. 279.

Chap. XXI. NATURAL SELECTION. 213

to run together in man and the lower animals. Thus white
terriers suffer more than those of any other colour from the
fatal distemper.^ In North America plum-trees are liable to
a disease which Downing^ believes is not caused by insects ;
the kinds bearing purple fruit are most affected, " and we have
" never known the green or yellow fruited varieties infected
" until the other sorts had first become filled with the knots."
On the other hand, peaches in Xorth America suffer much
from a disease called the yellows, which seems to be peculiar
to that continent, and more than nine-tenths of the victims,
" when the disease first appeared, were the yellow-fleshed
" peaches. The white-fleshed kinds are much more rarely
" attacked ; in some parts of the country never." In Mauri-
tius, the white sugar-canes have of late years been so severely
attacked by a disease, that many planters have been compelled
to give up growing this variety (although fresh plants were
imported from China for trial), and cultivate only red canes.^
Now, if these plants had been forced to struggle with other
competing plants and enemies, there cannot be a doubt that the
colour of the flesh or skin of the fruit, unimportant as these
characters are considered, would have rigorously determined
their existence.

Liability to the attacks of parasites is also connected with
colour. "White chickens are certainly more subject than dark-
coloured chickens to the gapes, which is caused by a parasitic
worm in the trachea.^" On the other hand, experience has
shown that in France the caterpillars which produce white
cocoons resist the deadly fungus better than those producing
yellow cocoons.^^ Analogous facts have been observed with
plants : a new and beautiful white onion, imported from
France, though planted close to other kinds, was alone attacked
by a parasitic fungus.^^ White verbenas are especially liable
to mildew.^^ Near Malaga, during an early period of the vine-

' Youatt on the Dog, p. 232. 379.

* 'The Fruit-ti-ees of America,' " Quatrefages, ' Maladies Actuelles
1845, p. 270 : for peaches, p. 466. du Ver a Soie,' 1859, pp. 12, 214.

* *Proc. Royal Soc. of Arts and '^ ' Gardener's Chronicle,' 1851, p.
Sciences of Mauritius,' 1852, p. 595.

czxzv. '^ * Journal of Horticulture,' 1862,

" 'Gardener's Chronicle,' 1856, p. p. 476.

214 SELECTION. Chap. XXI.

disease, the green sorts suffered most ; " and red and black
grapes, even when interwoven with the sick plants, suffered
not at all." In France whole groups of varieties were com-
paratively free, and others, such as the Chasselas, did not
afford a single fortunate exception ; but I do not know
whether any correlation between coloiir and liability to
disease was here observed.^* In a former chapter it was
shown how curiously liable one variety of the strawberry is
to mildew.

It is certain that insects regulate in many cases the range
and even the existence of the higher animals, whilst living
under their natural conditions. Under domestication light-
coloured animals suffer most : in Thuringia ^^ the inhabitants
do not like gre^^ white, or pale cattle, because the}^ are much
more troubled by various kinds of flies than the brown, red,
or black cattle. An Albino negro, it has been remarked,'^
was peculiarly sensitive to the bites of insects. In the West
Indies ^"^ it is said that " the only horned cattle fit for work
" are those which have a good deal of black in them. The
*' white are terribly tormented by the insects ; and they are
" weak and sluggish in proportion to the white."

In Devonshire there is a prejudice against white pigs,
because it is believed that the sun blisters them when turned
out ; ^^ and I knew a man who would not keep white pigs in
Kent, for the same reason. The scorching of flowers by the
sun seems likewise to depend much on colour; thus, dark
pelargoniums suffer most ; and from various accounts it is
clear that the cloth-of-gold variety will not withstand a
degree of exposure to sunshine which other varieties enjoy.
Another amateur asserts that not only all dark-coloured
verbenas, but likewise scarlets, suffer from the sun : " the
paler kinds stand better, and pale blue is perhaps the best of
all." So again with the heartsease (^Viola tricolor); hot

" * Gardener's Chronicle,' 1852, iv. West Indies,' ' Home and Col.

pp. 435, 691. Libr.iry,' p. 100.

^* Bechstein, *Naturgesch. Deutsch- ** Sidney's edit, of Youatt on the

lands,' 1801, B. i. s. 310. Pig, p. 24. I have given analogous

" Prichard, * Phys. Hist, of Man- facts in the case of mankind in my

kind,' 1851, vol. i. p. 224. ' Descent of Man,' 2nd edit. p. 195.

1' G. Lewis's ' Journal of Residence

Chap. XXI. NATURAL SELECTION. 215

weather suits the blotched sorts, whilst it destroys the beau-
tiful markings of some other kinds. ^^ During one extremely
cold season in Holland all red-flowered hyacinths were
observed to be very inferior in quality. It is believed by
many agriculturists that red wheat is hardier in northern
climates than white wheat.^*'

With animals, white varieties from being conspicuous are
the most liable to be attacked by beasts and birds of prey.
In parts of France and Germany where hawks abound, persons
are advised not to keep white pigeons ; for, as Parmentier
says, " it is certain that in a flock the white always first fall
victims to the kite." In Belgium, where so many societies
have been established for the flight of carrier-pigeons, white
is the one colour which for the same reason is disliked.^^
Prof. G. Jaeger-^ whilst fishing found four pigeons which
had been killed by hawks, and all were white ; on another
occasion he examined the ejrie of a hawk, and the feathers of
the pigeons which had been caught were all of a white or
yellow colour. On the other hand, it is said that the sea-
eagle {Falco ossifragus, Linn.) on the west coast of Ireland
picks out the black fowls, so that " the villagers avoid as
much as possible rearing birds of that colour." M. Daudin,'^^
speaking of white rabbits kept in warrens in Kussia, remarks
that their colour is a great disadvantage, as they are thus
more exposed to attack, and can be seen during bright
nights from a distance. A gentleman in Kent, who failed
to stock his woods with a nearly white and hardy kind of
rabbit, accounted in the same manner for their early dis-
appearance. Any one who will watch a white cat prowling
after her prey will soon perceive under what a disadvantage
she lies.

The white Tartarian cherry, " owing either to its colour

" 'Journal of Horticulture,' 1862, Feb. 25, 1865. With respect to black

pp. 476, 498 ; 1865, p. 460. With fowls, see a quotation in Thompson's

/espect to the heartsease, 'Gardener's 'Nat. Hist, of Ireland,' 1849, vol. i.

Chronicle,' 1863, p. 628. p. 22.

2" * Des Jacinthes, de leur Culture,' ^-' ' In Sachen Darwin's contra

1768, p. 53 : on wheat, ' Gardener's Wigand,' 1874, p. 70.

Chronicle,' 1846, p. 653. , " i guH, ^e la See. d'Acclimat.,'

" W. B. Tegetmeier, 'The Field,' torn, vii., 1860, p. 359.

216 SELECTION. Chap. XXL

being so much like that of the leaves, or to the fruit always
appearing from a distance unripe," is not so readily attacked
by birds as other sorts. The yellow-fruited raspberry, which
generally comes nearly true by seed, " is very little molested
by birds, who evidently are not fond of it ; so that nets may
be dispensed with in places where nothing else will protect
the red fruit."^* This immunity, though a benefit to the
gardener, would be a disadvantage in a state of nature both
to the cherry and raspberry, as dissemination depends on
birds. I noticed during several winters that some trees of
the yellow-berried holly, which were raised from seed from a
tree found wild by my father remained covered with fruit,
whilst not a scarlet berry could be seen on the adjoining trees
of the common kind. A friend informs me that a mountain-
ash (JPijrus aucuparid) growing in his garden bears berries
which, though not differently coloured, are always devoured
by birds before those on the other trees. This variety of
the mountain-ash would thus be more freely disseminated,
and the yellow-berried variety of the holly less freely, than
the common varieties of these two trees.

Independently of colour, trifling differences are sometimes
found to be of importance to plants under cultivation, and
would be of paramount importance if they had to fight their
own battle and to struggle with many competitors. The
thin-shelled peas, called ^ois sans parchemin, are attacked by
birds ^^ much more commonly than ordinary peas. On the
other hand, the purple-podded pea, which has a hard shell,
escaped the attacks of tomtits {Parus major) in my garden far
better than any other kind. The thin -shelled walnut like-
wise suffers greatly from the tomtit. ^^ These same birds
have been observed to pass over and thus favour the
filbert, destroying only the other kinds of nuts which grew
in the same orchard.^'

Certain varieties of the pear have soft bark, and these
suffer severely from wood - boring beetles ; whilst other

" 'Transact. Hort. Soc,' rol. i. 2nd " 'Gardener's Chronicle,' 1843, p

oeries, 1835, p. 275. For raspberries, 806.

see 'Gard. Chronicle/ 1855, p. 154, ^ Ibid., 1850, p. 732.

aAd \863, p. 245. »^ Ibid., 1860, p. 956.

CiiAr. XXL NATUKAL SELECTION. 217

varieties are known to resist their attacks mucli better.^^ In
North America the smoothness, or absence of down on the
fruit, makes a great difference in the attacks of the weevil,
" which is the uncompromising foe of all smooth stone-fruits ;"
and the cultivator " has the frequent mortification of seeing
nearly all, or indeed often the whole crop, fall from the trees
when half or tAvo-thirds grown." Hence the nectarine
suffers more than the peach. A particular variety of the
Morello cherry, raised in North America, is, without any
assignable cause, more liable to be injured by this same insect
than other cherry-trees.^^ From some unknown cause, certain
varieties of the apple enjoy, as we have seen, the great ad-
vantage in various parts of the world of not being infested by
the coccus. On the other hand, a j)articular case has been re-
corded in which aphides confined themselves to the \\ inter Nelis
pear and touched no other kind in an extensive orchard.-^" The
existence of minute glands on the leaves of peaches, nectarines,
and apricots, would not be esteemed by botanists as a charac-
ter of the least importance for they are present or absent in
closelv-related sub-varieties, descended from the same narent-
tree ; yet there is good evidence ^^ that the absence of
glands leads to mildew, which is highly injurious to these
trees.

A difference either in flavour or in the amount of nutriment
in certain varieties causes them to be more eagerly attacked
by various enemies than other varieties of the same species.
Bullfinches (Pyrrhula vulgaris) injure our fruit-trees by
devouring the flower-buds, and a pair of these birds have
been seen " to denude a large plum-tree in a couple of days of
almost every bud ;" but certain varieties^^ of the apple and
thorn [Cratcsgus oxyacautha) are more especially liable to
be attacked. A striking instance of this was observed in
Mr. Eivers's garden, in Nvhich two rows of a particular

2* J. De Jonghe, in ' Gardener's ^^ ' Journal of Horticulture,' Sept.

Chronicle,' 1860, p. 120. 26th, 1865, p. 254; see other re-

2* Downing, 'Fruit-trees of North ferences given in chap. x.

America,' pp. 266, 501 : in regai'd to ^ Mr. Stlby, in ' Mag. of Zoology

the cherry, p. 198. and Botany', Edinburgh, vol. ii., 1838,

« * Gardener's Chronicle,' 1849, p. p. 393.
?55.

y

218 SELECTION. Chap. XXL

variety of plum^^ had to be carefully protected, as tliey were
usually stripped of all their buds during the winter, whilst
other sorts growing near them escaped. The root (or en-
larged stem) of Laing's Swedish turnip is preferred by hares,
and therefore suffers more than other varieties. Hares and
rabbits eat down common rye before St. John's-day-rye,
when both grow together.^* In the south of France, when
an orchard of almond-trees is formed, the nuts of the bitter
variety are sown, " in order that they may not be devoured
by field-mice ;" ^^ so we see the use of the bitter principle
m almonds.

Other slight differences, which would be thought quite
unimportant, are no doubt sometimes of great service both
to plants and animals. The Whitesmith's gooseberry, as
formerly stated, produces its leaves later than other varieties,
and, as the flowers are thus left unprotected, the fruit
often fails. In one variety of the cherry, according to Mr.
Rivers,^^ the petals are much curled backwards, and in con-
sequence of this the stigmas were observed to be killed by
a severe frost ; whilst at the same time, in another variety
with incurved petals, the stigmas were not in the least
injured. The straw of the Fen ton wheat is remarkably un-
e(iual in height ; and a competent observer believes that
this variety is highly productive, partly because the ears
from being distributed at various heights ahove the ground
are less crowded together. The same observer maintains that
in the upright varieties the divergent awns are serviceable by
breaking the shocks when the ears are dashed together by the
wind.^'^ If several varieties of a plant are grown together,
and the seed is indiscriminately harvested, it is clear that the
hardier and more productive kinds will, by a sort of natural
selection, gradually prevail over the others ; this takes place,
as Colonel Le Couteur believes, ^^ in our wheat-fields, for, as

" The Reine Claude de Bavay, " Godron, ' De I'Espece,' torn. ii. p.

* Journal of Horticulture,' Dec. 27, 98.

1864, p. 61 1. ^« ' Gardener's Chron.,' 186G, p. 732.

^* Mr. Pusey, in 'Journal of R. ^7 'Gardener's Chronicle,' 1862, pp.

Agricult. Soc.,' vol. vi. p. 179. For 820, 821.

Swedish turnips, see ' Gard. Chron.,' ^* 'On the Varieties of Wheat/ p

1847, p. 91. 59^

Chap. XXL FAVOURABLE CIRCUMSTANCES. 219

formerly shown, no variety is qnite uniform in character.
The same thing, as I am assured by nurserymen, would take
place in our flower-gardens, if the seed of the different
varieties were not separately saved. AVhen the eggs of the
wild and tame duck are hatched together, the young wild
ducks almost invariably perish, from being of smaller size
and not getting their fair share of food.^^

Facts in sufficient number have now been given shovring
that natural selection often checks, but occasionally favours,
man's power of selection. These facts teach us, in addition,
a valuable lesson, namely, that we ought to be extremely
cautious in judging what characters are of importance in a
state of nature to animals and plants, which have to struggle
for existence from the hour of their birth to that of their
death, — their existence dejDcnding on conditions, about which
we are profoundly ignorant.

Circumstances favourable to Selection hj Man.

The possibility of selection rests on variability, and this, as
we shall see in the folloT\dng chapters, mainly depends on
changed conditions of life, but is governed by infinitely com-
plex and unknown laws. Domestication, even when long
continued, occasionally causes but a small amount of varia-
bility, as in the case of the goose and turkey. The slight
differences, however, which characterise each individual
animal and plant would in most, probably in all, cases suffice
for the production of distinct races through careful and pro-
longed selection. We see what selection, though acting on
mere individual differences, can effect when families of cattle,
sheep, pigeons, &c., of the same race, have been separately
bred during a number of years by different men without any
wish on their part to modify the breed. We see the same
fact in the difference between hounds bred for hunting in
different districts,*^ and in many other such cases.

In order that selection should produce any result, it is
manifest that the crossing of distinct races must be prevented ;
hence facility in pairing, as with the pigeon, is highly

^® Mr. Hewitt and others, in ' Jour- ** ' Encyclop. of Rural Sports,' p.

nai of Hort.,' 1862, p. 778. 405.

220 SELrCTION. Chap. XXI.

favourable for the work ; and difficulty in pairing, as with
cats, prevents the formation of distinct breeds. On nearly
the same principle the cattle of the small island of Jersey
have been improved in their milking qualities "with a
rapidity that could not have been obtained in a widely
extended country like France." *^ Although free crossing
is a danger on the one side which every one can see, too close
interbreeding is a hidden danger on the other side. Un-
favourable conditions of life overrule the power of selection.
Our improved heavy breeds of cattle and sheep could not
have been formed on mountainous pastures ; nor could dray-
horses have been raised on a barren and inhospitable land,
such as the Falkland Islands, where even the light horses of
La Plata rapidly decrease in size. It seems impossible to
preserve several English breeds of sheep in France; for as
soon as the lambs are weaned their vigour decays as the heat
of the summer increases :*^ it Avould be impossible to give
great length of wool to sheep within the tropics ; yet
selection has kept the Merino breed nearly true under diver-
sified and unfavourable conditions. The power of selection
is so great, that breeds of the dog, sheep, and poultry, of the
largest and smallest size, long and short beaked pigeons, and
other breeds with opposite characters, have had their charac-
teristic qualities augmented, though treated in every way
alike, being exposed to the same climate and fed on the same
food. Selection, however, is either checked or favoured by
the effects of use or habit. Our wonderful! ^''-improved pigs
could never have been formed if they had been forced to
search for their own food ; the English race-horse and grey-
hound could not have been improved up to their jDresent high
standard of excellence without constant training.

As conspicuous deviations of structure occur rarely, the
improvement of each breed is generally the result of the
selection of slight individual differences. Hence the closest
attention, the sharpest powers of observation, and indomitable
perseverance, are indispensable. It is, also, highly important

*^ Col, Le Couteur, ' Journal Roy. Agricult. Soc.,' vol. xiv., 1853, pp. 215,
Agricult. See.,' vol. iv. p. 43. 217.

*' Malingie - Nouel, Journal R

Chap. XXL FAVOURABLE CIRCUMSTANCES. 221

that many individuals of the breed which is to be improved
should be raised ; for thus there will be a better chance of the
appearance of variations in the right direction, and individuals
varjdng in an unfavourable manner may be freely rejected or
destroyed. But that a large number of individuals should be
raised, it is necessary that the conditions of life should favour
the propagation of the species. Had the peacock been reared
as easily as the fowl^ we should probably ere this have had
many distinct races. We see the importance of a large
number of plants, from the fact of nursery gardeners almost
always beating amateurs in the exhibition of new varieties.
In 1845 it was estimated "^^ that between 4000 and 5000
pelargoniums were annually raised from seed in England, yet
a decidedly improved variety is rarely obtained. At Messrs.
Carter's grounds, in Essex, where such flowers as the Lobelia,
Nemophila, Mignonette, &c., are grown by the acre for seed,
" scarcely a season passes without some new kinds beii^g
raised, or some improvement effected on old kinds.""^* At
Kew, as Mr. Beaton remarks, where many seedlings of common
plants are raised, " you see new forms of Laburnums, Spir{«as,
and other shrubs." *^ So with animals : Marshall,*"^ in speak-
ing of the sheep in one part of Yorkshire, remarks, " as they
belong to poor people, and are mostly in small lots, they never
can be improved." Lord Kivers, when asked how he suc-
ceeded in always having first-rate greyhounds, answered, " I
breed many, and hang many." This, as another man remarks,
" was the secret of his success ; and the same will be found in
exhibiting fowls, — successful comj)etitors breed largely, and
keep the best." *^

It follows from this that the capacity of breeding at an
early age and at short intervals, as with pigeons, rabbits, &c.,
facilitates selection ; for the result is thus soon made visible,
and perseverance in the work encouraged. It can hardly be
an accident that the great rnajorit}^ of the culinary and agri-
cultural plants which have 3delded numerous races are annuals

<* 'Gardener's Chronicle,' 1845, p. 368.
273. ■•« 'A Review of Reports,' 1808, p.

** 'Journal of Horticulture,' 1862, 406.
p. 157. *^ ' Gardener's Chronicle,' 1853, p.

" 'Cottage Gardener,' 1860, p. 45.

222 SELECTION. Chap. XXL

or biennials, wliicli therefore are capable of rapid propagation,
and thus of improvement. Sea-kale, asparagus, common and
Jerusalem artichokes, potatoes, and onions, must be excepted,
as they are perennials : but onions are propagated like annuals,
and of the other plants just specified, none, with the exception
of the potato, have yielded in this country more than one or
two varieties. In the Mediterranean region, where artichokes
are often raised from seed, there are several kinds, as I hear
from Mr. Bentham. No doubt fruit-trees, which cannot be
propagated quickly by seed, have yielded a host of varieties,
though not permanent races ; but these, judging from pre-
historic remains, have been produced at a comparatively late
period.

A species may be highly variable, but distinct races will
not be formed, if from any cause selection be not applied. It
would be difficult to select slight variations in fishes from
their place of habitation ; and though the carp is extremely
variable and is much attended to in Germany, only one well-
marked race has been formed, as I hear from Lord A. Russell,
namely the sjpiegel-carpe ; and this is carefully secluded from
the common scaly kind. On the other hand, a closely allied
species, the gold-fish, from being reared in small vessels, and
from having been carefully attended to by the Chinese, has
yielded many races. Neither the bee, which has been semi-
domesticated from an extremely remote period, nor the cochi-
neal insect, which was cultivated by the aboriginal Mexicans,*^
has yielded races ; and it would be impossible to match the
queen-bee with any particular drone, and most difficult to
match cochineal insects. Silk-moths, on the other hand, have
been subjected to rigorous selection, and have produced a host
of races. Cats, which from their nocturnal habits cannot be
selected for breeding, do not, as formerly remarked, yield dis-
tinct races within the same country. Dogs are held in
abomination in the East, and their breeding is neglected ;
consequently, as Prof. Moritz "Wagner ^^ reuiarks, one kind
alone exists there. The ass in England varies much in

** Isidore Geoffroy Saint-Hilaire, *^ ' Die Darwin'sche Theorie und das

* Hist. Nat. Gen.,' torn. iii. p. 49. ' On Migrationsgesetz der Organismen,'
the Cochineal Insect,' p. 46. 1868, p. 19.

CuAP. XXI. FAVOURABLE CIKCUMSTANCES. 223

colour and size ; hut as it is an animal of little value and
bred by poor people, there has been no selection, and distinct
races have not been formed. We must not attribute the
inferiority of our asses to climate, for in India they are of
even smaller size than in Europe. But when selection is
brought to bear on the ass, all is changed. Near Cordova, as I
am informed (Feb. 18 GO) by Mr. W. E. Webb, C.E., they are
carefully bred, as much as 200Z. having been paid for a
stallion ass, and they have been immensely improved. In
Kentucky, asses have been imported (for breeding mules)
from SjDain, Malta, and France ; these " seldom averaged
" more than fourteen hands high : but the Kentuckians, by
" great care, have raised them up to fifteen hands, and some-
" times even to sixteen. The prices paid for these splendid
" animals, for such they really are, will prove how much they
"are in request. One male, of great celebrity, was sold for
"upwards of one thousand pounds sterling." These choice
asses are sent to cattle-shows, a day being given for the'r
exhibition.^ *^

Analogous facts have been observed with plants : the
nutmeg-tree in the Malay archipelago is highly variable, but
there has been no selection, and there are no distinct races. ^^
The common mignonette (JReseda oclorata), from bearing in-
conspicuous flowers, valued solely for their fragrance, " remains
" in the same unimproved condition as when first intro-
•' duced." ^^ Our common forest-trees are very variable, as
may be seen in every extensive nursery-ground ; but as the}-
are not valued like fruit-trees, and as they seed late in life,
no selection has been applied to them ; consequently, as Mr.
Patrick Matthews remarks,^^ they have not yielded distinct
races, leafing at different periods, growing to different sizes,
and producing timber fit for different purposes. We have
gained only some fanciful and semi-monstrous varieties,
which no doubt appeared suddenly as we now see them.

Some botanists have argued that plants cannot have sc

50 Capt. Marryat, quoted by Blyth 645.

in 'Journ. Asiatic Soc. of Bengal,' ^^ Mr. Abbey, in ' Journal of Horti-

vol. xxviii. p. 229. culture,' Dec. 1, 1863, p. 430.

5» Mr. Oxley, 'Journal of the " 'On Naval Timber,' 1831, p.

Indian Archipelago,' vol. ii., 1848, p, 107.

224 SELECTION. Chap. XXI.

strong a tendency to vary as is generally supposed, because
many species long grown in botanic gardens, or unintention-
ally cultivated year after year mingled with our corn crops,
have not produced distinct races ; but this is accounted for
by slight variations not having been selected and 23ropagated.
Let a plant which is now grown in a botanic garden, or any
common weed, be cultivated on a large scale, and let a sharp-
sighted gardener look out for each slight variety and sow the
seed, and then, if distinct races are not produced, the argument
will be valid.

The importance of selection is likewise shown by consider-
ing special characters. For instance, with most breeds of
fowls the form of the comb and the colour of the plumage
have been attended to, and are eminently characteristic of
each race ; but in Dorkings, fashion has never demanded
uniformity of comb or colour ; and the utmost diversity in
these respects j)revails. Eose-combs, double-combs, cup-combs,
&c., and colours of all kinds, may be seen in purely bred and
closely related Dorking fowls, whilst other points, such as
the general form of body, and the presence of an additional
toe, have been attended to, and are invariably present. It
has also been ascertained that colour can be fixed in this
breed, as well as in any other.^*

During the formation or improvement of a breed, its
members will always be found to vary much in those
characters to which especial attention is directed, and of
which each slight improvement is eagerly s ;ught and selected.
Thus, with short-faced tumbler-pigeons, the shoitness of the
beak, shape of head and plumage, — with carriers, the length
of the beak and wattle, — with fantails, the tail and carriage,
— with Spanish fowls, the white face and comb, — with long-
eared rabbits, the length of ear, are all points which are
eminently variable. So it is in every case ; and the large
price paid for first-rate animals proves the difSculty of breed-
ing them up to the highest standard of excellence. This
subject has been discussed by fanciers,^^ and the greater

'^ Mr. Baily, in 'The Poultry Chro- •" < Cottage Gardener,' 1855, De-

nicie,' vol. ii., 1854:, p. 150. Also ceniber, p. 171; 1856, Janaary, pp.
vol. i. p. 342 ; vol. iii. p. 245. 248, 323.

Chap. XXI. CARRIED TO AN EXTREME. 225

prizes given for highly improved breeds, in comparison with
those given for old breeds which are not now undergoing
rapid improvement, have been fully justified. Kathusius
makes ^^ a similar remark when discussing the less uniform
character of improved Shorthorn cattle and of the English
horse, in comparison, for example, with the unennobled cattle
of Hungary, or with the horses of the Asiatic steppes. This
want of uniformity in the parts which at the time are under-
going selection chiefly depends on the strength of the prin-
ciple of reversion ; but it likewise depends to a certain
extent on the continued variability of the parts which have
recently varied. That the same parts do continue varying
in the same manner Ave must admit, for if it were not so,
there could be no improvement beyond an early standard of
excellence, and we know that such improvement is not only
possible, but is of general occurrence.

As a consequence of continued variability, and more espe-
cially of roxersion, all highly improved races, if neglected or
not subjected to incessant selection, soon degenerate. Youatt
gives a curious instance of this in some cattle formerly kept
in Glamorganshire ; but in this case the cattle were not fed
with sufficient care. Mr. Baker, in his memoir on the Horse,
sums up : " It must have been observed in the preceding
" pages that, whenever there has been neglect, the breed has
" proportionally deteriorated." ^'^ If a considerable number
of improved cattle, sheep, or other animals of the same race,
were allowed to breed freely together, with no selection, but
with no change in their condition of life, there can be no
doubt that after a score or hundred generations they would
be very far from excellent of their kind ; but, from what we
see of the many common races of dogs, cattle, fowls, pigeons,
&c., which without any particular care have long retained
nearly the same character, we have no grounds for believing
that they would altogether depart from their type.

It is a general belief amongst breeders that characters of
all kinds become fixed by long-continued inheritance. But I

*s ' Ueber Shorthorn Rindvieh,' 720. For the Glamorganshire cattle,
1857, s. 51. see Youatt on Cattle, p. 51

" *The Veterinary,' vo?. xiii. p.

226 SELECTION. Chap. XXI.

have attempted to show in the fourteenth chapter that this
belief apparently resolves itself into the following proposition,
namely, that all characters whatever, whether recently
acquired or ancient, tend to be transmitted, but that those
which have already long withstood all counteracting in-
fluences, will, as a general rule, continue to withstand them,
and consequently be faithfully transmitted.

Tendency in 3Ian to carry the jpraciice of Selection to an extreme

'point.

It is an important principle that in the process of selection
man almost invariably wishes to go to an extreme point.
Thus, there is no limit to his desire to breed certain kinds of
horses and dogs as fleet as possib^.e, and others as strong as
possible ; certain kinds of sheep for extreme fineness, and
others for extreme length of wool ; and he wishes to produce
fruit, grain, tubers, and other useful parts of plants, as large
and excellent as possible. With animals bred for amusement,
the same principle is even more powerful ; for fashion, as we see
in our dress, alwaj^s runs to extremes. This view has been
expressly admitted by fanciers. Instances were given in the
chapters on the pigeon, but here is another : Mr. Eaton, after
describing a comparatively new variety, namely, the Arch-
angel, remarks, " What fanciers intend doing wdth this bird
*' I am at a loss to know, whether they intend to breed it
" down to the tumbler's head and beak, or carry it out to the
" carrier's head and beak ; leaving it as they found it, is not
*' progressing." Ferguson, speaking of fowls, says, " their
" peculiarities, whatever they may be, must necessarily be
" fully developed : a little peculiarity forms nought but
" ugliness, seeing it violates the existing laws of symmetry."
So Mr. Brent, in discussing the merits of the sub-varieties of
the Belgian canary-bird, remarks, *' Fanciers always go to
" extremes ; they do not admire indefinite properties." ^^

This principle, which necessarily leads to divergence of
character, explains the present state of various domestic

^* J. M. Eaton, ' A Treatise on Mr. Brent, in * Cottage Gfcr'lener,'
Fancy Pigeons,' p. 82 ; Ferguson, on Oct. 18(30, p. 13.
liare and Prize Poultry,' p. 162 ;

Chap. XXI. CAERIED TO AN EXTREME. 227

races. We can thus see liow it is that race-horses and dray-
horses, greyhounds and mastiffs, which are opposed to each
other in every character, — how varieties so distinct as Cochin-
china fowls and bantams, or carrier-pigeons with very long
beaks, and tumblers with excessively short beaks, have been
derived from the same stock. As each breed is slowly im-
proved, the inferior varieties are first neglected and finally
lost. In a few cases, by the aid of old records, or from inter-
mediate varieties still existing in countries where other
fashions have prevailed, we are enabled partially to trace the
graduated changes through which certain breeds have passed.
Selection, whether methodical or unconscious, always tending
towards an extreme point, together with the neglect and slow
extinction of the intermediate and less-valued forms, is the
key which unlocks the mystery of how man has produced
such wonderful results.

In a few instances selection, guided by utility for a single
purpose, has led to convergence of character. All the im-
proved and different races of the pig, as Nathusius has well
shown,^^ closely approach each other in character, in their
shortened legs and muzzles, their almost hairless, large,
rounded bodies, and small tusks. We see some degree of
convergence in the similar outline of the body in well-bred
cattle belonging to distinct races. ''° I know of no other such
cases.

Continued divergence of character depends on, and is indeed
a clear proof, as previously remarked, of the same parts con-
tinuing to vary in the same direction. The tendency to mere
general variability or plasticity of organisation can certainly
be inherited, even from one parent, as has been shown by
Gartner and Kolreuter, in the production of varying h3^brids
from two species, of which one alone was variable. It is in
itself probable that, when an organ has varied in any manner,
it will again vary in the same manner, if the conditions which
first caused the being to vary remain, as far as can be judged,
the same. This is either tacitly or expressly admitted by all

*' 'Die Racen des Sohweines,' 1860, head by M. de Quatrefages, ' Unite de
8. 48. I'Espfece Humaine,' 1861, p. 119.

"" See some good remarks on this

228 SELECTION. Chap. XXI.

horticulturists : if a gardener observes one or two additional
petals in a flower, he feels confident that in a few generations
he will be able to raise a double flower, crowded with petals.
Some of the seedlings from the weeping Moccas oak were so
prostrate that they only crawled along the ground. A seedling
from the fastigate or upright Irish yew is described as differ-
ing greatly from the parent-form " by the exaggeration of
the fastigate habit of its branches." ^^ Mr. Shirrefif, who has
been highly successful in raising new kinds of wheat, remarks,
" A good variety may safely be regarded as the forerunner of
a better one." ^'^ A great rose-grower, Mr. Rivers, has made
the same remark with respect to roses. Sageret,*"^ who had
large experience, in speaking of the future progress of fruit-
trees, observes that the most important principle is " that the
more plants have departed from their original type, the more
they tend to depart from it." There is apparently much
truth in this remark ; for we can in no other wa}'' understand
the surprising amount of difference between varieties in the
parts or qualities which are valued, whilst other parts retain
nearly their original character.

The foregoing discussion naturally leads to the question,
what is the limit to the possible amount of variation in any
part or quality, and, consequently, is there any limit to what
selection can effect ? Will a race-horse ever be reared fleeter
than Eclipse? Can our prize-cattle and sheep be still further
improved? Will a gooseberry ever weigh more than that
produced by "London" in 1852? Will the beet-root in
France yield a greater percentage of sugar ? Will future
varieties of wheat and other grain produce heavier crops than
our present varieties ? These questions cannot be ]30sitively
answered ; but it is certain that we ought to be cautious in
answering them by a negative. In some lines of variation
the limit has probably been reached. Youatt believes that
the reduction of bone in some of our sheep has already been
carried so far that it entails great delicacy of constitution.^*

«' Verlot, * Des Varietes,' 1865, p. " ' Pomologie Physiolog.,' 1830, p.

94. 106.

«2 Mr. Patrick Shirreff, in * Gard. " Youatt on Sheep, p. 521.
Chronicle,' 1858, p. 771.

Chap. XXI. SELECTION. 229

But seeing the great improvement within recent times in our
cattle and sheep, and especially in our pigs; seeing the
wonderful increase in weight in our poultry of all kinds
during the last few years; he would be a bold man who
would assert that perfection has been reached. It has often
been said that Eclipse never was, and never will be, beaten in
speed by any other horse; but on making inquiries I find
that the best judges believe that our present race-horses are
fleeter. ^^ The attempt to raise a new variety of wheat more
productive than the many old kinds, might have been thought
until lately quite hopeless; but this has been effected by
Major Hallett, by careful selection. With respect to almost
all our animals and plants, those who are best qualified to
judge do not believe that the extreme point of perfection has
yet been reached even in the characters which have already
been carried to a high standard. For instance, the short-
faced tumbler-pigeon has been greatly modified ; nevertheless,
according to Mr. Eaton, ^^ " the field is still as open for fresh
competitors as it was one hundred years ago." Over and
over again it has been said that perfection had been attained
with our flowers, but a higher standard has soon been reached.
Hardly any fruit has been more improved than the straw-
berry, yet a great authority remarks,^^ " it must not be
concealed that we are far from the extreme limits at which
we may arrive."

Ko doubt there is a limit beyond which the organisation
cannot be modified compatibly with health or life. The
extreme degree of fleetness, for instance, of which a terrestrial
animal is capable, may have been acquired by our present
race-horses ; but as Mr. Wallace has well remarked, ^^ the
question that interests us, " is not whether indefinite and un-
" limited change in any or all directions is possible, but
" whether such difierences as do occur in nature could have
" been produced by the accumulation of varieties by selection."
And in the case of our domestic productions, there can be no

^^ See also Stonehenge, 'British Chron.,' 1858. p. 173.

Rural Sports/ edition of 1871, p. 384. "* 'Contributions to the Theory of

** 'A Treatise on the Almond Natural Selection,' 2nd edit., 1871,

Tumbler,* p. i. p. 292.

*' M. J. de Jonghe, in *Gard.

32

230 SELECTION. Chap. XXL

doubt tliat many parts of tlie organisation, to whicli man has
attended, have been thus modified to a greater degree than
the corresponding parts in the natural species of the same
genera or even families. We see this in the form and size
of our light and heavy dogs or horses, — in the beak and many
other characters of our pigeons,— in the size and quality of
many fruits, — in comparison with the species belonging to
the same natural groups.

Time is an important element in the formation of our
domestic races, as it permits innumerable individuals to be
born, and these when exposed to diversified conditions are
rendered variable. Methodical selection has been occasionally
practised from an ancient period to the present clay, even by
semi-civilised people, and during former times will have pro-
duced some effect. Unconscious selection will have been still
more effective ; for during a lengthened period the more
valuable individual animals will occasionally have been
saved, and the less valuable neglected. In the course of time,
different varieties, especially in the less civilised countries,
will also have been more or less modified through natural
selection. It is generally believed, though on this head we
have little or no evidence, that new characters in time be-
come fixed ; and after having long remained fixed it seems pos-
sible that under new conditions they might again be rendered
variable.

How great the lapse of time has been since man first do-
mesticated animals and cultivated plants, we begin dimly to
see. When the lake-dwellings of Switzerland were inhabited
during the Neolithic period, several animals were already
domesticated and various plants cultivated. The science of
language tells us that the art of ploughing and sowing the
land was followed, and the chief animals had been already
domesticated, at an epoch so immensely remote, that the
Sanskrit, Greek, Latin, Gothic, Celtic, and Sclavonic languages
had not as yet diverged from their common parent-tongne.*"^

It is scarcely possible to overrate the effects of selection
occasionally carried on in various ways and places during
thousands of generations. All that we know, and, in a still
«» Max Miiller, 'Science of Language,' 1861, p. 223.

Chap. XXI. SELECTION. 231

stronger degree, all that we do not know,"*' of the history of
the great majority of our breeds, even of our more modern
breeds, agrees with the view that their production, through
the action of unconscious and methodical selection, has been
almost insensibly slow. When a man attends rather more
closel}^ than is usual to the breeding of his animals, he is
almost sure to improve them to a slight extent. They are
in consequence valued in his immediate neighbourhood, and
are bred by others ; and their characteristic features, whatever
these may be, will then slowly but steadily be increased,
sometimes by methodical and almost alwaj^s by unconscious
selection. At last a strain, deserving to be called a sub-variety,
becomes a little more widely known, receives a local name,
and spreads. The spreading will have been extremely slow
during ancient and less civilised times, but now is rapid.
By the time that the new breed had assumed a somewhat
distinct character, its history, hardly noticed at the time,
will have been completely forgotten ; for, as Low remarks, ^^
" we know how quickly the memory of such events is
efiaced."

As soon as a new breed is thus formed, it is liable through
the same process to break up into new strains and sub-
varieties. For different varieties are suited for, and are
valued under, different circumstances. Fashion changes, but,
should a fashion last for even a moderate length of time, so
strong is the principle of inheritance, that some effect will
probably be impressed on the breed. Thus varieties go on
increasing in number, and history shows us how wonderfully
they have increased since the earliest records.'^^ As each
new variety is produced, the earlier, intermediate, and less
valuable forms will be neglected, and perish. When a breed,
from, not being valued, is kept in small numbers, its extinc-
tion almost inevitably follows sooner or later, either from
accidental causes of destruction or from close interbreeding ;
and this is an event which, in the case of well-marked breeds,
excites attention. The birth or production of a new domestic
race is so slow a process that it escapes notice ; its death or

^<» Youatt on Cattle, pp. 116, 128. " Volz, ' Beitrage zur Kulturge-

'' * Domesticated Animals,' p. 188. schichte,' 1852, s. 99 et passim.

232 SELECTION. Chap. XXI.

destruction is comparatively sudden, is often recorded, and
when too late sometimes regretted.

Several authors have drawn a wide distinction between
artificial and natural races. The latter are more uniform in
character, possessing in a high degree the appearance of
natural species, and are of ancient origin. They are generally
found in less civilised countries, and have probably been
largely modified by natural selection, and only to a small
extent by man's unconscious and methodical selection. They
have, also, during a long period, been directly acted on by
the physical conditions of the countries which they inhabit.
The so-called artificial races, on the other hand, are not so
uniform in character ; some have a semi-monstrous character,
such as " the wry-legged terriers so useful in rabbit- shoot-
ing,""^ turnspit dogs, ancon sheep, niata oxen, Polish fowls,
fantail-pigeons, &c. ; their characteristic features have gene-
rally been acquired suddenly, though subsequently increased
by careful selections in many cases. Other races, which
certainly must be called artificial, for they have been largely
modified by methodical selection and by crossing, as the
English race-horse, terrier-dogs, the English game-cock,
Antwerp carrier-pigeons, &c., nevertheless cannot be said to
have an unnatural appearance ; and no distinct line, as it
seems to me, can be drawn between natural and artificial
races.

It is not surprising that domestic races should generally
present a difi'erent aspect from natural species. Man selects
and propagates modifications solely for his own use or fancy,
and not for the creature's own good. His attention is struck
by strongly marked modifications, which have appeared
suddenly, due to some great disturbing cause in the organi-
sation. He attends almost exclusively to external characters ;
and when he succeeds in modifying internal organs, — when
for instance he reduces the bones and offal, or loads the viscera
with fat, or gives early maturity, &c., — the chances are
strong that he will at the same time weaken the constitution.
On the other hand, when an animal has to struggle through-
out its life with many competitois and enemies, under
^' Blaine, ' Encyclop. of Rural Sports,' p, 213,

Chap. XXI. SELECTION. 233

circumstances inconceivably comi3lex and liable to change,
modifications of the most varied nature in the internal organs
as well as in external characters, in the functions and mutual
relations of parts, will be rigorously tested, preserved, or
rejected. Natural selection often checks man's comparatively
feeble and capricious attempts at improvement ; and if it were
not so, the result of his work, and of nature's work, would be
even still more different. Nevertheless, we must not overrate
the amount of difference between natural species and domestic
races ; the most experienced naturalists have often disputed
whether the latter are descended from one or from several
aboriginal stocks, and this clearly shows that there is no
palpable difference between sjDecies and races.

Domestic races propagate their kind far more truh% and
endure for much longer periods, than most naturalists are
willing to admit. Breeders feel no doubt on this head : ask
a man who has long reared Shorthorn or Hereford cattle,
Leicester or Southdown sheep, Spanish or Game poultry,
tumbler or carrier-pigeons, whether these races may not have
been derived from common progenitors, and he will probably
laugh you to scorn. The breeder admits that he may hope
to produce sheep with finer or longer wool and with better
carcases, or handsomer fowls, or carrier-pigeons with beaks
just perceptibly longer to the practised eye, and thus be
successful at an exhibition. Thus far he will go, but
no farther. He does not reflect on what follows from
adding up during a long course of time many slight,
successive modifications ; nor does he reflect on the former
existence of numerous varieties, connecting the links in each
divergent line of descent. He concludes, as was shown in
the earlier chapters, that all the chief breeds to which he
has long attended are aboriginal productions. The systematic
naturalist, on the other hand, who generally knows nothing
of the art of breeding, who does not pretend to know hoAV
and when the several domestic races were formed, who cannot
have seen the intermediate gradations, fur they do not now
exist, nevertheless feels no doubt that these races are sprung
from a single source. But ask him whether the closely
allied natural species which he has studied may not have

234 SELECTION. Chap. XXI,

descended from a common progenitor, and he in his turn will
perhaps reject the notion with scorn. Thus the naturalist
and breeder may mutually learn a useful lesson from each
other.

Summary on Selection hy Man. — There can be no doubt that
methodical selection has effected and will effect wonderful
results. It was occasionally practised in ancient times, and
is still practised by semi-civilised people. Characters of the
highest importance, and others of trifling value, have been
attended to, and modified. I need not here repeat what has
been so often said on the part which unconscious selection
has played : we see its power in the difference between flocks
whieh have been separately bred, and in the slow changes,
as circumstances have slowly changed, which many animals
have undergone in the same country, or when transported
into a foreign land. We see the combined effects of methodi-
cal and unconscious selection, in the great amount of
difference in those parts or qualities which are valued by man
in comparison with the parts which are not valued, and
consequently have not been attended to. Natural selection
often determines man's power of selection. We sometimes
err in imagining that characters, which are considered as
unimportant by the systematic naturalist, could not be
affected by the struggle for existence, and could not be acted
on by natural selection ; but striking cases have been given,
showing how great an error this is.

The possibility of selection coming into action rests on
variability ; and this is mainly caused, as we shall hereafter
see,' by changes in the conditions of life. Selection is some-
times rendered difficult, or even impossible, by the conditions
being opposed to the desired character or quality. It is
sometimes checked by the lessened fertility and weakened
constitution which folloAv from long-continued close inter-
breeding. That methodical selection may be successful, the
closest attention and discernment, combined with unwearied
patience, are absolutel}^ necessary ; and these same qualities,
though not indispensable, are highly serviceable in the case
of unconscious selection. It is almost necessary that a large
number of individuals should be reared ; for thus there will

Chap. XXI. SELECTION. 235

be a fair chance of variations of the desired nature arising,
and of every individual with the slightest blemish or in any
degree inferior being freely rejected. Hence length of time
is an important element of success. Thus, also, reproduction
at an early age and at short intervals favours the work.
Facility in pairing animals, or their inhabiting a confined
area, is advantageous as a check to free crossing. Whenever
and wherever selection is not practised, distinct races are not
formed within the same country. When any one part of the
body or one quality is not attended to, it remains either un-
changed or varies in a fluctuating manner, whilst at the same
time other parts and other qualities may become permanently
and greatly modified. But from the tendency to reversion and
to continued variability, those parts or organs which are now
undergoing rapid improvement through selection, are likewise
found to vary much. Consequently highly-bred animals when
neglected soon degenerate ; but we have no reason to believe
that the efifects of long-continued selection would, if the con-
ditions of life remained the same, be soon and completely lost.
Man always tends to go to an extreme point in the selection,
whether methodical or unconscious, of all useful and pleasing
qualities. This is an important principle, as it leads to con-
tinued divergence, and in some rare cases to convergence of
character. The possibility of continued divergence rests on
the tendency in each part or organ to go on varying in the
same manner in which it has already varied ; and that this
occurs, is proved by the steady and gradual improvement of
many animals and plants during lengthened periods. The
principle of divergence of character, combined with the
neglect and final extinction of all previous, less-valued, and
intermediate varieties, explains the amount of difference and
the distinctness of our several races. Although we may have
reached the utmost limit to which certain characters can be
modified, yet we are far from having reached, as we have
good reason to believe, the limit in the majority. of cases,
rinall}^ from the difference between selection as carried on
by man and by nature, we can understand how it is that
domestic races often, though by no means always, difiier in
general aspect from closely allied natural species.

236 SELECTION. Chap. XXL

Througlioiit this chapter and elsewhere I have spoken of
selection as the paramount power, yet its action absolutely
depends on what we in our ignorance call spontaneous or
accidental variability. Let an architect be compelled to
build an edifice with uncut stones, fallen from a precipice.
The shape of each fragment may be called accidental ; jet
the shape of each has been determined by the force of gravity,
the nature of the rock, and the slope of the precipice, — events
and circumstances, all of which depend on natural laws ; but
there is no relation between these laws and the purpose for
which each fragment is used by the builder. In the same
manner the variations of each creature are determined by
fixed and immutable laws ; but these bear no relation to the
living structure which is slowly built up through the power
of selection, whether this be natural or artificial selection.

If our architect succeeded in rearing a noble edifice, using
the rough wedge-shaped fragments for the arches, the longer
stones for the lintels, and so forth, we should admire his skill
even in a higher degree than if he had used stones shaped for
the purpose. So it is with selection, whether applied by
man or by nature ; for although variability is indispensably
necessary, yet, when we look at some highly complex and
excellently adapted organism, variability sinks to a quite
subordinate position in importance in comparison with selec-
tion, in the same manner as the shape of each fragment used
by our supposed architect is unimportant in comparison with
Ills skill.

Chap. XXII. CAUSES OF VARIABILITY. 237

CHAPTER XXII.

CAUSES OF VARIABILITY.

VARIABILITY 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, EXCESS OF NUTRIMENT — SLIGHT
CHANGES SUFFICIENT — EFFECTS OF GRAFTING ON THE VARIABILITY OF
SEEDLING - TREES — DOMESTIC PRODUCTIONS BECOME HABITUATED TO
CHANGED CONDITIONS— ON THE ACCUMULATIVE ACTION OF CHANGED
CONDITIONS — CLOSE INTERBREEDING AND THE IMAGINATION OF THE
MOTHER SUPPOSED TO CAUSE VARIABILITY — CROSSING AS A CAUSE OF
THE APPEARANCE OF NEW CHARACTERS — VARIABILITY FROM THE COM-
MINGLING 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 VARIABILITY,

We will now consider, as far as we can, the causes of the
almost universal variability of our domesticated productions.
The subject is an obscure one ; but it may be useful to probe
our ignorance. Some authors, for instance Dr. Prosper Lucas,
look at variability as a necessary contingent on reproduction,
and as much an aboriginal law as growth or inheritance.
Others have of late encouraged, perhaps unintentionally, this
view by speaking of inheritance and variability as equal and
antagonistic principles. Pallas maintained, and he has had
some followers, that variability depends exclusively on the
crossing of primordially distinct forms. Other authors attri-
bute variability to an excess of food, and with animals to an
excess relatively to the amount of exercise taken, or again to
the effects of a more genial climate. That these causes are
all effective is highly j)robable. But we must, I think, take
a broader view, and conclude that organic beings, when sub-
jected during several generations to any change whatever in
their conditions, tend to vary ; the kind of variation which
ensues depending in most cases in a far higher degree on tlie
nature or constitution of the being, than on the nature of the
changed conditions.

238 CAUSES OF VARIABILITY. Chap. XXII.

Those authors who believe that it is a law of nature that
each individual should differ in some slight degree from every
other, may maintain, apparently with truth, that this is the
fact, not only with all domesticated animals and cultivated
plants, but likewise with all organic beings in a state of
nature. The Laplander by long practice knows and gives
a name to each reindeer, though, as Linnceus remarks, " to
distinguish one from another among such multitudes was
beyond my comprehension, for they were like ants on an ant-
hill." In Germany shepherds have won wagers by recog-
nising each sheep in a flock of a hundred, which they had
never seen until the previous fortnight. This power of
discrimination, however, is as nothing compared to that
which some florists have acquired. Verlot mentions a
gardener who could distinguish 150 kinds of camellia, when
not in flower ; and it has been positively asserted that the
famous old Dutch florist "Voorhelm, who kept above 1200
varieties of the hj^acinth, was hardly ever deceived in knowing
each variety by the bulb alone. Hence we must conclude
that the bulbs of the hyacinth and the branches and leaves
of the camellia, though appearing to an unpractised eye
absolutely undistinguishable, jet really differ.^

As Linnteus has compared the reindeer in number to an^^s.
I may add that each ant knows its fellow of the same com-
munity. Several times I carried ants of the same species
(Formica rufa) from one ant-hill to another, inhabited
apparently by tens of thousands of ants ; but the strangers
were instantly detected and killed. I then put some ants
taken from a very large nest into a bottle strongly perfumed
with assafoetida, and after an interval of twenty-four hours
returned them to their home ; they were at first threatened
by their fellows, but were soon recognised and allowed to
pass. Hence each ant certainly recognised, independently of
odour, its fellow ; and if all the ants of the same community
have not some countersign or watchword, they must present
to each other's senses some distinguishable character.

^ ' Des Jacinthes,' &c., Amsterdam, lated by Sir J. E. Smith, a'oI. i. p.

1768, p, 43; Verlot, 'Des Varietes,' 314. the statement in regard to

&c., p. 86. On the reindeer, see German shepherds is given on the

Linnffius, ' Tour in Lapland,' trans- authority of Dr. Weinland.

Chap. XXII.

CAUSES OF VARIABILITY.

239

The dissimilarity of brothers or sisters of the same family,
and of seedlings from the same capsule, may be in part
accounted for by the unequal blending of the characters of
the two parents, and by the more or less complete recovery
through reversion of ancestral characters on either side ; but
we thus only push the difficulty further back in time, for
what made the parents or their progenitors different ? Hence
the belief'^ that an innate tendenc}^ to Yary exists, indepen-
dently of external differences, seems at first sight probable.
But even the seeds nurtured in the same capsule are not sub-
jected to absolutely uniform conditions, as they draw their
nourishment from different points ; and we shall see in a future
chapter that this difference sometimes suffices to affect the
character of the future plant. The greater dissimilarity of
the successive children of the same family in comparison with
twins, which often resemble each other in external appearance,
mental disposition, and constitution, in so extraordinary a
manner, apparently proves that the state of the parents at the
exact period of conception, or the nature of the subsequent
embryonic development, has a direct and powerful influence
on the character of the offspring. Nevertheless, when we

' Miiller's ' Physiology,' Eng. trans-
lation, vol. ii. p. 1662. With respect
to the similarity of twins in consti-
tution, Dr. William Ogle has gi.ven me
the following extract from Professor
Trousseau's Lectures (' Clinique ]\Iedi-
cale,' torn. i. p. 523), in which a
curious case is recorded : — " J'ai donne
mes soins i deux freres juraeaux, tous
deux si extraordinairement ressem-
blants qu'il m'etait impossible de les
■^ecunnaitre, a moins de les voir I'un
a cote de I'aiitre. Cette ressemblance
physique s'etendait plus loin : ils
ivaient, permettez-moi I'expression,
nne similitude pathologique plus re-
marquable encore. Ainsi I'un d'eux
que je voyais aux neothermes k Paris
malade d'une ophthalmic rhumatis-
male me disait, ' En ce moment mon
frere doit avoir une ophthulmie comme
la mienne ; ' et comme je m'etais recrie,
.'1 me montrait quelques jours apres
une lettre qu'il venait de recevoir de

ce frere alors a Vienne, et qui lui ecri-
vait en eff'et — 'J'ai mon ophthalmie,
tu dois avoir la tienne.' Quelque sin-
gulier que ceci puisse paraitre, le fait
n'en est pas moins exact : on ne me I'a
pas raconte, je I'ai vu, et j'en ai vu
d'autres analogues dans ma pratique.
Ces deux jumeaux etaient aussi tous
deux asthmatiques, et asthmatiques
a un efiroyable degre. Originaires de
Marseille, ils n'ont jamais pu de-
meurer dans cette ville, oil leurs
interets los appelaient souvent. sans
etre pris de leurs acces ; jamais ils n'en
eprouvaient a Paris. Bien mieux. il
leur suffisait de gagner Toulon pour
etre gueris de leurs attaques de Mar-
seille. Voyageant sans cesse et dan-
tous pays pour leurs affaires, ii-
av.tient remarque que certaim's
localites leur etaient funestes, qi..:
dans d'autres ils etaient exempts d?
tout phenomene d'oppression."

240 CAUSES OF VARIABILITY. Chap. XXII.

reflect on the individual differences between organic beings in
a state of nature, as shown by every wild animal knowing its
mate ; and when we reflect on the infinite diversity of the
many varieties of our domesticated productions, we may well
be inclined to exclaim, though falsely as I believe, that
Vaiiability must be looked at as an ultimate fact, necessarily
contingent on rej)roduction.

Those authors who adopt this latter view would probably
deny that each separate variation has its own proper exciting
cause. Although we can seldom trace the precise relation
between cause and effect, yet the considerations presently to
be given lead to the conclusion that each modification must
have its own distinct cause, and is not the result of what we
blindly call accident. The following striking case has been
communicated to me b}'' Dr. William Ogle. Two girls, born
as twins, and in all respects extremely alike, had their little
fingers on both hands crooked ; and in both children the
second bicuspid tooth of the second dentition, on the right side
in the upper jaw was misplaced ; for, instead of standing in a
line with the others, it grew from the roof of the mouth
behind the first bicuspid. Neither the parents nor any other
members of the family were known to have exhibited any
similar peculiarity ; but a son of one of these girls had the
same tooth similarly misplaced. Kow, as both the girls were
affected in exactly the same manner, the idea of accident is at
once excluded : and we are compelled to admit that there
must have existed some precise and sufficient cause which, if
it had occurred a hundred times, would have given crooked
fingers and misplaced bicuspid teeth to a hundred children.
It is of course possible that this case may have been due to
reversion to some long-forgotten progenitor, and this would
much weaken the value of the argument. I have been led to
think of the probability of reversion, from having been told by
Mr. Galton of another case of twin girls born with their little
fingers slightly crooked, which they inherited from their
maternal grandmother.

We will now consider the general arguments, which appear
to me to have great weight, in favour of the view that varia-
tions of all kinds and degrees are directly or indirectly caused

Ch.*^'. XXII. CAUSES OF VARIABILITY. 241

by the conditions of life to which, each being, and more
especially its ancestors, have been exposed.

No one doubts that domesticated productions are more
variable than organic beings which have never been removed
from their natural conditions. Monstrosities graduate so in-
sensibly into mere variations that it is impossible to separate
them ; and all those who have studied monstrosities believe
that they are far commoner with domesticated than with wild
animals and plants ; ^ and in the case of plants, monstrosities
would be equally noticeable in the natural as in the cultivated
state. Under nature, the individuals of the same species are
exposed to nearly uniform conditions, for they are rigorously
kept to their proper places by a host of competing animals and
plants ; they have, also, long been habituated to their condi-
tions of life ; but it cannot be said that they are subject to
quite uniform conditions, and they are liable to a certain
amount of variation. The circumstances under which our
domestic productions are reared are widely different : they
are protected from competition ; they have not only been
removed from their natural conditions and often from their
native land, but they are frequently carried from district to
district, where they are treated differently, so that they rarely
remain during any considerable length of time exposed to
closely similar conditions. In conformity with this, all our
domesticated productions, with the rarest exceptions, vary far
mors than natural species. The hive-bee, which feeds itself and
follows in most respects its natural habits of life, is the least
variable of all domesticated animals, and probably the goose
is the next least variable; but even the goose varies more
than almost any wild bird, so that it cannot be affiliated with
perfect certainty to any natural species. Hardly a single
plant can be named, which has long been cultivated and
propagated by seed, that is not highly variable ; common rye
{Secede cereale) has afforded fewer and less marked varieties
than almost any other cultivated plant ; * but it may be

3 Isid. Geoffroy St.-Hilaiie, * Hist. 1841, p. 115.
ies Anomalies,' torn. iii. p. 052; Mo- ■* Metzger, ' L)ie Getrei learten,

quin-'fandon, * Teratologie Vcg^tale,' 1811, s. '69.

242 CAUSES OF VARIABILITY. Chap. XXIJ.

doubted wlietlier the variations of this, the least valuable of
all our cereals, have been closely observed.

Bud- variation, which was fully discussed in a former chap-
ter, shows us that variability may be quite independent of
seminal reproduction, and likewise of reversion to long-lost
ancestral characters. No one will maintain that the sudden
appearance of a moss-rose on a Provence-rose is a return to a
former state, for mossiness of the calyx has been observed in
no natural species ; the same argument is applicable to varie-
gated and laciniated leaves ; nor can the appearance of necta-
rines on peach-trees be accounted for on the principle of rever-
sion. But bud-variations more immediately concern us, as
they occur far more frequently on plants which have been
highly cultivated during a length of time, than on other and
less highly cultivated plants ; and very few well-marked
instances have been observed with plants growing under
strictly natural conditions. I have given one instance of an
ash-tree growing in a gentleman's pleasure-grounds ; and
occasionally there may be seen, on beech and other trees,
twigs leahng at a different period from the other branches.
But our forest trees in England can hardly be considered as
living under strictly natural conditions ; the seedlings are
raised and protected in nursery-grounds, and must often be
transplanted into places where wild trees of the kind would
not naturally grow. It would be esteemed a prodigy if a dog-
rose growing in a hedge produced by bud-variation a moss-
rose, or a wild bullace or wild cherrj'-tree jdelded a branch
bearing fruit of a different shape and colour from the ordinar}'-
fruit. The prodigy would be enhanced if these varying
branches were found capable of propagation, not only by
grafts, but sometimes bj^ seed ; yet analogous cases have
occurred with many of our highly cultivated trees and herbs.

These several considerations alone render it probable that
variability of every kind is directly or indirectly caused by
changed conditions of life. Or, to put the case under another
point of view, if it were possible to expose all the individuals
of a species during many generations to absolutely uniform
conditions of life, there would be no variability.

Chap. XXII. CAUSES OF VARIABILITY. 243

On the Nature of the Changes in the Conditions of Life which

induce Variahilitij.

From a remote period to the present day, under climates
and circumstances as different as it is possible to conceive,
organic beings of all kinds, when domesticated or cultivated,
have varied. We see this with the many domestic races of
quadrupeds and birds belonging to different orders, with gold-
fish and silkworms, with plants of many kinds, raised in
various quarters of the world. In the deserts of northern
Africa the date-palm has yielded thirty-eight varieties ; in
the fertile plains of India it is notorious how many varieties
of rice and of a host of other plants exist ; in a single Poly-
nesian island, twenty-four varieties of the bread-fruit, the
same number of the banana, and twenty-two varieties of the
arum, are cultivated by the natives ; the mulberry-tree in
India and Europe has yielded many varieties serving as food
for the silkworm ; and in China sixtj^-three varieties of the
bamboo are used for various domestic purposes.^ These facts,
and innumerable others which could be added, indicate that
a change of almost any kind in the conditions of life suffices
to cause variability — different changes acting on different
organisms.

Andrew Knight ^ attributed the variation of both animals
and plants to a more abundant supply of nourishment, or to a
more favourable climate, than that natural to the species. A
more genial climate, however, is far from necessary ; the
kidney-bean, which is often injured by our spring frosts, and
peaches, which require the protection of a wall, have varied
much in England, as has the orange-tree in northern Italy,
where it is barely able to exist. "^ Kor can we overlook the

5 On the date-palm, see Vogel, of the Pandanus and other trees in

'Annals and Mag. of JSat. Hist.,' the Marianne Island, see 'Hooker's

1854-, p. 460. On Indian varieties, Miscellany,' vol. i. p. 308. On the

Dr. F. Hamilton, ' Transact. Linn. bamboo in China, see Hue's ' Chinese

Soc.,' vol. xiv. p. 296. On the varie- Empire,' vol. ii. p. 307.
ties cultivated in Tahiti, see Dr. ^ 'Treatise on the Culture of the

Bennett, in Loudon's ' Mag. of N. Apple,' &c., p. 3.
Hist.,' vol. v., 1832, p. 484. Also ' Gallesio, 'Teoria della Ripro-

Ellis, ' Polynesian Researches,' vol. i. duzione Veg.,' p. 125.
pp. 370, 375. On twenty varieties

244

CAUSES OF VARIABILITY.

Chap. XXn.

fact, though not immediately connected with our present
Bubject, that the plants and shells of the Arctic regions are
eminently variable.^ Moreover, it does not appear that a
change of climate, whether more or less genial, is one of the
most potent causes of variability ; for in regard to plants Alph.
De Candolle, in his ' Geographic Botanique,' repeatedly shows
that the native country of a plant, where in most cases it has
been longest cultivated, is that where it has yielded the
greatest number of varieties.

It is doubtful whether a change in the nature of the food
is a potent cause of variability. Scarcely any domesticated
animal has varied more than the pigeon or the fowl, but
their food, especially that of highly-bred pigeons, is generally
the same. Kor can our cattle and sheep have been subjected
to any great change in this respect. But in all these cases
the food probably is much less varied in kind than that which
was consumed by the species in its natural state.^

Of all the causes which induce variability, excess of food,
whether or not changed in nature, is jDrobably the most
powerful. This view was held with regard to plants by
Andrew Knight, and is now held by Schleiden, more esj)ecially
in reference to the inorganic elements of the food.^° In
order to give a plant more food it suffices in most cases to
grow it separately, and thus prevent other plants robbing its
roots. It is surprising, as I have often seen, how vigorously
our common wild species flourish when planted by them-
selves, though not in hio;hty manured land ; separate growth
is, in fact, the first step in cultivation. We see the converse
of the belief that excess of food induces variability in the
following statement by a great raiser of seeds of all kinds :^^

* See Dr. Hooker's Memoir on
Arctic Plants in ' Linn. Transact.,'
voL xxiii. part ii. Mr. Woodward,
and a higher authority cannot be
quoted, speaks of the Arctic mollusca
(in his ' Rudimentary Treatise,' 1856,
p. 355) as remarkably subject to
variation.

^ Bechstein, in his ' Naturge-
schuihte der Stubenvcigel,' 1840, s,
238, has some good remarks on this

subject. He states that his canary-
birds varied in coloui*, though kept on
uniform food.

" 'The Plant,' by Schleiden, trans-
lated by Henfrey, 1848, p. 169. See
also Alex. Braun, in ' Bot. Memoirs,'
Ray Soc, 1853, p. 313.

'' Messrs. Hardy and Son, of Mal-
don, in ' Gard. Chronicle,' 1856, p.
458. Carriere, ' Production et Fixa
Vion des Varietes,' 1865, p. 31.

Chap. XXII. CAUSES OF VARIABILITY. 245

" It is a rule invariably with us, when we desire to keep a
*' true stock of any one kind of seed, to grow it on poor land
" without dung ; but when we grow for quantity, we act
" contrary, and sometimes have dearly to repent of it."
According also to Carriere, who has had great experience with
flower-garden seeds, " On remarque en general les plantes de
*' vigeur moyenne sont celles qui conservent le mieux leurs
" caracteres."

In the case of animals the want of a proper amount of
exercise, as Bechstein remarked, has perhaps played, inde-
pendently of the direct effects of the disuse of any parti-
cular organ, an important part in causing variability. We
can see in a vague manner that, when the organised and
nutrient fluids of the body are not used during growth, or by
the wear and tear of the tissues, they will be in excess ; and
as growth, nutrition, and reproduction are intimately allied
processes, this superfluity might disturb the due and proper
action of the reproductive organs, and consequently afiect the
character of the future offspring. But it may be argued that
neither an excess of food nor a superfluity in the organised
fluids of the body necessarily induces variability. The goose
and the turkey have been well fed for many generations, yet
have varied very little. Our fruit-trees and culinary plants,
which are so variable, have been cultivated from an ancient
period, and, though they probably still receive more nutri-
ment than in their natural state, yet they must have received
during many generations nearly the same amount ; and it
might be thought that they would have become habituated to
the excess. Nevertheless, on the whole, Knight's view, that
excess of food is one of the most potent causes of variability,
appears, as far as I can judge, probable.

Whether or not our various cultivated plants have received
nutriment in excess, all have been exposed to changes of
various kinds. Fruit-trees are grafted on diSerent stocks,
and grown in various soils. The seeds of culinary and agri-
cultural plants are carried from place to place; and during
the last century the rotation of our crops and the manures
used have been greatly changed.

Slight changes of treatment often suflSce to induce varia-

246 CAUSES OP VARIABILITY. Chap. XXII

bility. The simple fact of almost all our cultivated plants
and domesticated animals having varied in all places and at
all times, leads to this conclusion. Seeds taken from common
English forest-trees, grown under their native climate, not
highly manured or otherwise artificially treated, yield seed-
lings which vary much, as may be seen in exery extensive
seed-bed. I have shown in a former chapter what a number
of well-marked and singular varieties the thorn (Cratcegus
oxycantha) has produced : yet this tree has been subjected to
hardly any cultivation. In Staffordshire I carefully examined
a large number of two British plants, namely Geranium pliceum
and pyrenaicum, which have never been highly cultivated.
These plants had spread spontaneously by seed from a
common garden into an open plantation ; and the seedlings
varied in almost every single character, both in their flower
and foliage, to a degree which I have never seen exceeded ;
yet they could not have been exposed to any great change in
their conditions.

With respect to animals, Azara has remarked with much
surprise,^ ^ that, whilst the feral horses on the Pampas are
always of one of three colours, and the cattle always of a
uniform colour, yet these animals, when bred on the un-
enclosed estancias, though kept in a state which can hardly
be called domesticated, and apparently exposed to almost
identically the same conditions as when they are feral, never-
theless display a great diversity of colour. So again in India
several species of fresh-water fish are only so far treated
artificially, that they are reared in great tanks; but this
small change is sufficient to induce much variability.^^

Some facts on the effects of grafting, in regard to the
variability of trees, deserve attention. Cabanis asserts that
when certain pears are grafted on the quince, their seeds yield
a greater number of varieties than do the seeds of the same
variety of pear w^hen grafted on the wild pear.^'* But as the
pear and quince are distinct species, though so closely related

" 'Quadrupedes du Paraguay,' 1839, pp. 266, 268, 313.

1801, torn. ii. p. 319. ^^ Quoted by Sageret, ' Pom. Phys.,

»3 M'Clelland on Indian Cyprinida?, 1830, p. 43, This statement, how-

* Asiatic Researches,' vol. xix. part ii., ever, is not believed by Decaisne.

Chap. XXII. CAUSES OF VARIABILITY. 247

that the one can he readily grafted and succeeds admirably on
the other, the fact of variability being thus caused is not sur-
prising ; as we are here enabled to see the cause, namely, the
very different nature of the stock and graft. Several North
American varieties of the plum and peach are well known to
reproduce themselves truly by seed ; but Downing asserts,^^
*' that when a graft is taken from one of these trees and
" placed upon another stock, this grafted tree is found to lose
"its singular property of producing the same variety by
'' seed, and becomes like all other worked trees ;" — that is, its
seedlings become highly variable. Another case is worth
giving : the Lalande variety of the walnut-tree leafs between
April 20th and May 15th, and its seedlings invariably
inherit the same habit ; whilst several other varieties of
the walnut leaf in June. Now, if seedlings are raised from
the May-leafing Lalande variety, grafted on another May-
leafing variety, though both stock and graft have the same
early habit of leafing, yet the seedlings leaf at various times,
even as late as the 5th of June.^^ Such facts as these are
well fitted to show on what obscure and slight causes vari-
ability depends.

I may here just allude to the appearance of new and valuable
varieties of fruit-trees and of A^heat in woods and waste places,
which at first sight seems a most anomalous circumstance. In
France a considerable number of the best pears have been discovered
in woods ; and this has occurred so frequently, that Piteau asserts
that " improved varieties of our cultivated fruits rarely originate
with nurserymen." In England, on the other hand, no instance of
a good pear having been found wild has been recorded ; and Mr.
Eivers informs me that he knows of only one instance with apples,
namely, the Bess Poole, which was discovered in a wood in Notting-
hamshire. This diiference between the two countries may be in part
accounted for by the more favourable climate of France, but chiefly

*^ 'The Fruits of America,' 1845, Poiteau's remark is quoted in ' Gar-

p. 5. dener's Slag.,' vol. iv.. 1828, p. 385.

*® M. Cardan, in 'Comptes Ren- See ' Gard. Chronicle,' 1862, p. 335,

dus,' Dec. 1848, quoted in 'Gard. for another case of a new varietv of

Chronicle,' 1849, p. 101. the pear found in a hedge in France.

*^ M. Alexis Jordan mentions four Also for another case, see Loudon's

excellent pears found in woods in ' Eneyclop. i>f Gardening,' p. 901.

P'rance, and alludes to others (' Mem. Mr. Rivers has given rne similar

A.cad. de Lyon,' torn ii. 1852, p. 159). information.

248 CAUSES OF VAE I ABILITY. Chap. XXII

from the great number of seedlings which spring up there in the
woods. I infer that this is the case from a remark made by a
French gardener,^^ who regards it as a national calamity that such
a number of pear-trees are periodically cut down for firewood, before
they have borne fruit. The new varieties which thus spring up in
the woods, though they cannot have received any excess of nutri-
ment, will have been exposed to abruptly changed conditions, but
whether this is the cause of their production is very doubtful.
These varieties, however, are probably all descended ^^ from old
cultivated kinds growing in adjoining orchards — a circumstance
which will account for their variability ; and out of a vast number
of varying trees there will always be a good chance of the appear-
ance of a valuable kind. In North America, where fruit-trees
frequently spring up in waste places, the Washington ijeai was
found in a hedge, and the Emperor peach in a wood.^"

With respect to wheat, some writers have spoken-^ as if it were
an ordinary event for new varieties to be found in waste places ; the
Fenton wheat was certainly discovered growing on a pile of basaltic
detritus in a quarry, but in such a situation the plant would
probably receive a sufficient amount of nutriment. The Chidham
wheat was raised from an ear found on a hedge; and Hunters
wheat was discovered hy the roadside in Scotland, but it is not said
that this latter variety grew where it was found.^^

Whether our domestic productions would ever become so
completely habituated to the conditions under which they
now live, as to cease varying, we have no sufficient means for
judging'. But, in fact, our domestic productions are never
exposed for a great length of time to uniform conditions, and
it is certain that our most anciently cultivated plants, as well
as animals, still go on varying, for all have recently under-
gone marked improvement. In some few cases, however,
plants have become habituated to new conditions. Thus,
Metzger, who cultivated in Germany during many years
numerous varieties of wheat, brought from different coun-
tries,^^ states that some kinds were at first extremely vari-
able, but gradually, in one instance after an interval of

>* Duval, 'Hist, du Poirier,' 1849, aboriginal species,

p. 2. "** Downing, 'Fruit-trees of North

*^ I infer that this is the fact from America,' p. 422 ; Foley, in ' Transact.

Van Mons* statement (' Arbres Frui- Hort. Soc.,' vol. vi. p. 412.

tiers,' 1835, torn. i. p. 446) that he '^ ' Gard. Chronicle,' 1847, p. 244.

findsin the woods seedlings resembling "^"^ 'Gardener's Chronicle,' 1841, p.

all the chief cultivated races of both o83 ; 1850, p. 700 ; 1854, p. 650.

the pear and apple. Van Mons, how- ^^ ' Die Getreidearten,' 1843, s. 66,

ever looked at these wild varieties as 116, 117.

Chap. XXII. CAUSES OF VARIABILITY. 249

twenty-five years, became constant ; and it does not appear
that this resulted from the selection of the more constant
forms.

On the Accumulative Action of changed Conditions of Life. —
AVe have good grounds for believing that the influence of
changed conditions accumulates, so that no effect is produced
on a species until it has been exposed during several genera-
tions to continued cultivation or domestication. Universal
experience shows us that when new flowers are first introduced
into our gardens they do not vary ; but ultimately all, with
the rarest exceptions, vary to a greater or less extent. In
a few cases the requisite number of generations, as well as
the successive steps in the progress of variation, have been
recorded, as in the often quoted instance of the Dahlia.^*
After several years' culture the Zinnia has only lately (1860j
begun to vary in any great degree. *' In the first seven or
" eight years of high cultivation, the Swan Eiver daisy
" {Bracliycome iheridifolia) kept to its original colour ; it then
" varied into lilac and purple and other minor shades."-^
Analogous facts have been recorded with the Scotch rose. In
discussing the variability of plants several experienced hor-
ticulturists have spoken to the same general effect. Mr.
Salter '^^ remarks, " Every one knows that the chief difficulty
*' is in breaking through the original form and colour of the
" species, and every one will be on the look-out for any
" natural sport, either from seed or branch ; that being once
" obtained, however trifling the change may be, the result
" depends upon himself." M. de Jonghe, who has had so much
success in raising new varieties of pears and strawberries,^^
remarks with respect to the former, " There is another prin-
" ciple, namely, that the more a type has entered into a state
" of variation, the greater is its tendency to continue doing
" so ; and the more it has varied from the original type, the

2* Sabine, in' Hort. Transact,,' vol. ^^ 'The Chrysanthemum, its His-

iii. p. 225; Brona, ' Geschichte der tory, &c.,' 1865, p. 3.
Natur,' b. ii. s. 119. ^^ 'Gardener's Chron.,* 1855, ]),

" 'Journal of Horticulture,' 1861, 5-i ; 'Journal of Horticulture,' Ma/

p. 112; on Zinnia, 'Gardener's 9, 1865, p. 363.
Chi-onicle,* 1860, p. 852.

250 CAUSES OF VARIABILITY. Chap. XXII

" more it is disposed to vary still farther." We have, indeed,
already discussed this latter point when treating of the power
which man possesses, through selection, of continually aug-
menting in the same direction each modification ; for this
power depends on continued variability of the same general
kind. The most celebrated horticulturist in France, namely,
Vilmorin,^^ even maintains that, when any particular varia-
tion is desired, the first step is to get the plant to vary in
any manner whatever, and to go on selecting the most
variable individuals, even though they vary in the wrong
direction; for the fixed character of the species being once
broken, the desired variation will sooner or later appear.

As nearly all our animals were domesticated at an extremely
remote epoch, we cannot, of course, say whether they varied
quickl}'- or slowly when first subjected to new conditions.
But Dr. Bachman-^ states that he has seen turkeys raised
from the eggs of the wild species lose their metallic tints and
become spotted with white in the third generation. ]Vlr.
Yarrell many years ago informed me that the wild ducks
bred on the ponds in St. James's Park, which had never been
crossed, as it is believed, with domestic ducks, lost their true
plumage after a few generations. An excellent observer,^*^
who has often reared ducks from the eggs of the wild bird,
and who took precautions that there should be no crossing
with domestic breeds, has given, as previously stated, full
details on the changes which they gradually undergo. He
found that he could not breed these wild ducks true for more
than five or six generations, "as they then proved so much
" less beautiful. The white collar round the neck of the
" mallard became much broader and more irregular, and
" white feathers appeared in the ducklings' wings." They
increased also in size of body; their legs became less fine,
and they lost their elegant carriage. Fresh eggs were then
procured from wild birds ; but again the same result followed.
In these cases of the duck and turkey we see that animals,

2'* Quoted by Verlot, ' Des Varietes,' ton, 1855, p. 14.

&c., 1865, p. 28. 30 j^ir. Hewitt, ' Journal of Hort.,

^' ' Examination of the Characteris- 1863, p. 39.
tics of Genera and Species :' Charles-

Chap. XXII. CAUSES OF VARIABILITY. 231

like plants, do not depart from their primitive type until
they have been subjected during several generations to
domestication. On the other hand, Mr. Yarrell informed me
that the Australian dingos, bred in the Zoological Gardens,
almost invariably produced in the first generation puppies
marked with white and other colours ; but these introduced
dingos had probably been procured from the natives, who
keep them in a semi-domesticated state. It is certainly a
remarkable fact that changed conditions should at first pro-
duce, as far as we can see, absolutely no effect; but that
they should subsequently cause the character of the species
to change. In the chapter on pangenesis I shall attempt to
throw a little light on this fact. •

Eeturning now to the causes which are supposed to induce
variability. Some authors ^^ believe that close interbreeding
gives this tendency, and leads to the production of monstro-
sities. In the seventeenth chapter some few facts were
advanced, showing that monstrosities are, as it appears,
occasionally thus induced ; and there can be no doubt that
close interbreeding causes lessened fertility and a weakened
constitution ; hence it may lead to variability : but 1 have
not sufBcient evidence on this head. On the other hand,
close interbreeding, if not carried to an injurious extreme,
far from causing variability, tends to fix the character of each
breed.

It was formerly a common belief, still held by some persons,
that the imagination of the mother affects the child in the
womb.^^ This view is evidently not applicable to the lower
animals, which lay unimpregnated eggs, or to plants. Dr.
AVilliam Hunter, in the last century, told my father that
during many years every woman in a large London Lying-in
Hospital was asked before her confinement whether an^'thing
had specially affected her mind, and the answer was written
down ; and it so happened that in no one instance could a
coincidence be detected between the woman's answer and any

*' Devay, ' Mariages Consanguins,' ^^ Mullei* has conclusively argued

pp. 97, 125. In conversation I have against this belief, ' Elements of

found two or three naturalists of the Phys.,' Eng. translat., vol. ii. 1842>

siime opinion. p. 1405.

252 CAUSES OP VARIABILITY. Chap. XXII.

abnormal structure ; but when slie knew the nature of the
structure, she frequently suggested some fresh cause. The
belief in the power of the mother's imagination may perhaps
have arisen from the children of a second marriage resembling
the previous father, as certainly sometimes occurs, in accord-
ance with the facts given in the eleventh chapter.

Crossing as a Cause of Variahility. — In an early part of this
chapter it was stated that Pallas^^ and a few other naturalists
maintain that variabilit}'- is wholly due to crossing. If this
means that new characters never spontaneously appear in our
domestic races, but that they are all directly derived from
certain aboriginal species, .the doctrine is little less than
absurd ; for it implies that animals like Italian greyhounds,
pug-dogs, bull-dogs, pouter and fantail pigeons, &c., were able
to exist in a state of nature. But the doctrine may mean
something widel}^ different, namely, that the crossing of
distinct species is the sole cause of the first appearance of new
characters, and that without this aid man could not have
formed his various breeds. As, however, new characters have
appeared in certain cases by bud- variation, we may conclude
with certainty that crossing is not necessary for variability.
It is, moreover, certain that the breeds of various animals,
such as of the rabbit, pigeon, duck, &c., and the varieties of
several plants, are the modified descendants of a single wild
species. Nevertheless, it is probable that the crossing of
two forms, when one or both have long been domesticated
or cultivated, adds to the variability of the offspring, inde-
pendently of the commingling of the characters derived from
the two parent-forms ; and this implies that new characters
actually arise. But we must not forget the facts advanced
in the thirteenth chapter, which clearly prove that the act
of crossing often leads to the reappearance or reversion of
long-lost characters ; and in most cases it would be impossible
to distinguish between the reappearance of ancient characters
and the first appearance of absolutely new characters. Practi-
cally, whether new or old, they would be new to the breed in
which they reappeared.

33 ' Act. Acad. St. Petersburg,' 1780, part ii, p, 84, &c.

Chap. XXII. CAUSES OF VARIABILITY. 253

Gartner declares,^^ and his experience is of the highest rahie on
Biich a point, that, when he crossed native plants wliich had not
been cultivated, he never once saw in the offspring any new character ;
but that from the odd manner in which the characters derived from
the parents were combined, they sometimes appeared as if new.
^Yhen, on the other hand, he crossed cultivated plants, he admits
that new characters occasionally appeared, but he is strongly
inclined to attribute their appearance to ordinary variability, not
in any M'ay to the cross. An opposite conclusion, however, apj)ears
to me the more probable. According to Kulreuter, hybrids in the
genus Mirabilis vary almost infinitely, and he describes new and
singular characters in the form of the seeds, in the colour of the
anthers, in the cotyledons being of immense size, in new and highly
peculiar odours, in the flowers expanding early in the season, and
in their closing at night. With respect to one lot of these hybrids,
he remarks that they presented characters exactly the reverse of
what might have been expected from their parentage.^^

Prof. Lecoq"^ speaks strongly to the same effect in regard to this
same genus, and asserts that many of the hybrids from Mirabilis
jalapa and multifiora might easily be mistaken for distinct species,
and adds that they differed in a greater degree than the other
species of the genus, from M. jalapa. Herbert, also, has describeu^'^
certain hybrid Ehododendions as being '' as unlike all others in
" foliage, as if they had been a separate species." The common
experience of floriculturists proves that the crossing and recrossing
of distinct but allied plants, such as the species of Petunia, Calceo-
laria, Fuchsia, Verbena, &c., induces excessive variability; hence
the appearance of quite new characters is probable. M. Carriere^"
has lately discussed this subject : he states that Erythrina cristaf/tilli
had been multiplied by seed for many years, but hcid not yielded
any varieties : it was then crossed with the allied A', herbacea, and
" the resistance was now overcome, and varieties were produced
" with flowers of extremely different size, form, and colour."

From the general and apparently well-founded belief that the
crossing of distiiKit species, besides commingling their characters,
adds greatly to their variability, it has probably arisen that some
botanists have gone so far as to maintain ^^ that, when a genus
includes only a single species, this when cultivated never varies.
The proposition made so broadly cannot be admitted; but it is
probably true that the variability of monotypic genera when culti-

3* ' Bastarderzeugung,* s. 249, 255, ^* Abstracted in ' Gard. Chronicle,'

295. 1860, p. 1081.

^^ 'Nova Acta, St. Petersburg,' 39 This was the opinion of the elder

1794, p. 378 ; 1795, pp. o07, 31:3, De Candolle, as quoted in ' Die. Class.

316 ; 1787, p. 407. d'Hist. Nat.,' torn. viii. p. 405. Puvis,

^^ *De la Fe'condation,' 18G2, p. in his work, ' De la Degeneration,*

311. 1837, p. 37, hua discussed thjs sam<*

" * Amaryllidaceae,' 1837, p. 362. point.

33

254 CAUSES OF VARIABILITY. Chap. XXIL

vated is generally less tlian that of genera including numerous
species, and this quite independently of the effects of crossing.
I have shown in my ' Origin of Species; that the species belonging
to small genera generally yield a less number of varieties in a state
of nature than those belonging to large genera. Hence the species
of small genera would, it is probable, produce fewer varieties under
cultivation than the already variable species of larger genera.

Although we have not at present sufficient evidence that the
crossing of species, which have never been cultivated, leads to the
appearance of new characters, this apparently does occur with
species which have been already rendered in some degree variable
through cultivation. Hence crossing, like any other change in the
conditions of life, seems to be an element, probably a potent one, in
causing variability. But we seldom have the means of distinguish-
ing, as previously remarked, between the appearance of really new
characters and the reappearance of long-lost characters, evoked
through the act of crossing. I will give an instance of the difficulty
in distinguishing such cases. The species of Datura may be divided
into two sections, those having white flowers with green stems,
and those having purple flowers with brown stems : now Naudin^**
crossed Datura la^vis and ferox, both of which belong to the white
section, and raised from them 205 hybrids. Of these hybrids, every
one had brow-n stems and bore purple flowers; so that they re-
sembled the si)ecies of the other section of the genus, and not their
own two parents. Naudin was so much astonished at this fact,
that he was led carefully to observe both parent-species, and he
discovered that the pure seedlings of D. ferox, immediately after
germination, had dark purple stems, extending from the young roots
up to the cotyledons, and that this tint remained ever afterwards
as a ring round the base of the stem of the plant when old. Now I
have shown in the thirteenth chapter that the retention or exaggera-
tion of an early character is so intimately related to reversion, that it
evidently comes under the same principle. Hence probably we
ought to look at the purple flowers and brown stems of these
hybrids, not as new characters due to variabiHty, but as a return
to the former state of some ancient progenitor.

Independently of the appearance of new characters from crossing,
a few words may be added to what has been said in former chapters
on the unequal combination and transmission of the characters
proper to the two parent-forms. When two species or races are
crossed, the offspring of the first generation are generally uniform,
but those subsequently produced display an almost infinite diversity
of character. He who wishes, says Kolreuter,*^ to obtain an endless
number of varieties from hybrids should cross and recross them.
There is also much variability when hybrids or mongrels are
reduced ox absorbed by repeated crosses with either pure parent-

<o 'Comptes RenduSj'Novembre 21, ^* ' Nova Acta, St. Petersburg,

1864, p. 838. ^ 1794, p. 391.

Chap. XXII. CAUSES OF VARIABILITY. 255

form : and a still higher degree of Yariability when three distinct
species, and most of all when four species, are blended together by
successive crosses. Beyond this point Gartner,^^on whose authority
the foregoing statements are made, never succeeded in effecting a
union; but Max Wichura^^ united six distinct species of willows
into a single hybrid. The sex of the parent species affects in an
inexplicable manner the degree of variability of hybrids; for
Gartner" repeatedly found that when a hybrid was used as a father
and cither one of the pure parent-species, or a third species, was
used as the mother, the offspring were more variable than when the
same hybrid was used as the mother, and either pure parent or the
same third species as the father : thus seedlings from Dianthus
harhatus crossed by the hybrid D. chinensi-harbatus were more
variable than those raised from this latter hybrid fertilised by the
pure D. hurhdtus. Max Wichura*^ insists strongly on an analogous
result with his hybrid willows. Again Gartner ''^ asserts that the
degree of variability sometimes differs in hybrids raised from re-
ciprocal crosses between the same two species; and here the sole
difference is, that the one species is first used as the father and then
as the mother. On the whole we see that, independently of the
appearance of new characters, the variability of successive crossed
generations is extremely complex, partly from the offspring partaking
unequally of the characters of the two parent-forms, and more
especially from their unequal tendency to revert to such characters
or to those of more ancient progenitors.

On the Manner and on the Period of Action of the Causes which
induce Variahility. — This is an extremely obscure subject, and
we need here only consider, whether inherited variations are
due to certain parts being acted on after they have been
formed, or through the reproductive system being affected
before their formation ; and in the former case at what period
of growth or development the effect is produced. AVe shall
see in the two following chapters that various agencies, such
as an abundant supply of food, exposure to a different climate,
increased use or disuse of parts, &o., prolonged during several
generations, certainly modify either the whole organisation or
certain organs ; and it is clear at least in the case of bud-
vuriation that the action cannot have been through the repro-
ductive system.

" 'Bastarderzeugung,'s. 507, 516, ** ' Bastarderzeugung,'s. 452, 507

572. *^ ' Die Bastardbefruchtung,' s. 56

*^ ' Die Bastardbefruchtung,' &c., *^ ' Bastarderzeugung,* s. 423.
1S65, s. 24.

256 CAUSES OF VAEIABILITY. Chap. XXIL

With respect to the part which the reproductive system takes in
cavising* variability, we have seen in the eighteenth chapter that
even slight changes in the conditions of hfe have a remarkable
power in causing a greater or less degree of sterility. Hence it
seems not improbable that beings generated through a system so
easily affected should themselves be affected, or should fail to
inherit, or inherit in excess, characters proper to their parents.
Wc know that certain groups of organic beings, but with exceptions
in each group, have their reproductive systems much more easily
affected by changed conditions than other groups; for instance,
carnivorous birds more readily than carnivorous mammals, and
parrots more readily than pigeons ; and this fact harmonises with
the apparently capricious manner and degree in which various
groups of animals and plants vary under domestication.

Kolreuter^^ was struck with the parallelism between the excessive
variability of hybrids when crossed and recrossed in various w^ays, —
these hybrids having their reproductive powers more or less affected,
— and the variability of anciently cultivated plants. Max Wichura'**
has gone one step farther, and shows that with many of our highly
cultivated plants, such as the hyacinth, tulip, auricula, snapdragon,
potato, cabbage, &c., which there is no reason to believe have been
hybridised, the anthers contain many irregular pollen-grains in the
same state as in hybrids. He finds also in certain wild forms, the
same coincidence between the state of the pollen and a high degree
of variability, as in many species of Eubus ; but in R. ccesius and
idceiis, which are not highly variable species, the pollen is sound.
It is also notorious that many cultivated plants, such as the banana,
pine-apple, bread-fruit, and others previously mentioned, have their
reproductive organs so seriously affected as to be generally quite
sterile ; and when they do yield seed, the seedlings, judging from
the large number of cultivated races which exist, must be variable
in an extreme degree. These facts indicate that there is some
relation between the state of the reproductive organs and a tendency
to variability ; but we must not conclude that the relation is strict.
Although many of our highly cultivated plants may have their
pollen in a deteriorated condition, yet, as we have previously seen,
they yield more seeds, and our anciently domesticated animals are
more prolific, than the corresponding species in a state of nature.
The peacock is almost the only bird which is believed to be less
fertile under domestication than in its native state, and it has varied
in a remarkably small degree. From these considerations it would
seem that changes in the conditions of life lead either to sterility
or to variability, or to both ; and not that sterility induces variability.
On the whole it is probable that any cause affecting the organs of

*^ * Dritte Fortsetzung,' &c., 1766, Berkeley on the same subjeci, iu

s. 85. 'Journal ol lioynl lioit. Soc.,' 18<)6,

*^ *Die BastardbefruchtvTng,* &c., }». 80.
1865, s. 92 : see also the Rev. M. J.

f

Chap. XXII. CAUSES OF VAEIABILITY. 257

reproduction would likewise affect their product, — that is, the
offspring thus generated.

The period of life at which the causes that induce variability act,
is likewise an obscure subject, which has been discussed by various
authors.'*^ In some of the cases, to be given in the following chapter,
of modifications from the direct action of changed conditions, which
are inherited, there can be no doubt that the causes have acted on
the mature or nearly mature animal. On the other hand, monstrosi-
ties, which cannot be distinctly separated from lesser variations, are
often caused by the embryo beiug injured whilst in the mother's
womb or in the egg. Thus I. Geoffroy Saint-Hilaire ^" asserts that
poor women who work hard during their pregnancy, and the mothers
of illegitimate children trouliled in their minds and forced to conceal
their state, are far more liable to give birth to monsters than women
in easy circumstances. The eggs of the fowl when placed upright
or otherwise treated unnaturally frequently produce monstrous
chickens. It would, however, appear that complex monstrosities
are induced more frequently during a rather late than during a very
early period of embryonic life ; but this may partly result from some
one part, which has been injured during an early period, affecting
by its abnormal growth other parts subsequently developed; and
this would be less likely to occur with parts injured at a later period.^^
When any part or organ becomes monstrous through abortion, a
rudiment is generally left, and this likewise indicates that its
development had already commenced.

Insects sometimes have their antennae or legs in a monstrous
condition, the krvse of which do not possess either antennae or legs ;
and in these cases, as Quatrefages ^- believes, we are enabled to see
the precise period at which the normal progress of development
was troubled. But the nature of the food given to a caterpillar
sometimes affects the colours of the moth, without the caterpillar
itself being affected ; therefore it seems possible that other characters
in the mature insect might be indirectly modified through the larvae.
There is no reason to suppose that organs which have been rendered
monstrous have always been acted on during their development ; the
cause may have acted on the organisation at a much earlier stage.
It is even probable that either the male or female sexual elements,
or both, before their union, may be affected in such a manner as to
lead to modifications in organs developed at a late period of life ; in
nearly the same manner as a child may inherit from his father a
disease which does not appear until old age.

*® Dr P Lucar. has given a history several memoirs by M. Dareste here-
of opinion on this subject : ' Hered. after referred to are of special
Nat..' 1847, torn. i. p 175. value on this whole subject.

*• 'Hist, des Anomali<»*!,' torn. iii. ^'^ See his interesting work, ' Meta-

p. 499. morphoses de I'Homme,' &c., 1862, p

^> Ibid., torn. iii. pp. 392, 501 The 129.

258 CAUSES OF VAEIABILITY. Chap. XXII.

In accordance with the facts above given, which prove that in
many ca<=es a close relation exists between variability and the sterility
following from changed conditions, we may conclude that the ex-
citing cause often acts at the earliest possible period, namely, on the
sexual elements, before impregnation has taken place. That an
affection of the female sexual element may induce variability we may
likewise infer as probable from the occurrence of bud- variations ;
for a bud seems to be the analogue of an ovule. But the male element
is apparently much oftener affected by changed conditions, at least
in a visible manner, than the female element or ovule; and we know
from Gartner's and Wichura's statements that a hybrid used as
the father and crossed with a pure species gives a greater degree of
variability to the offspring, than does the same hybrid when used as
the mother. Lastly, it is certain that variability may be transmitted
through either sexual element, whether or not originally excited in
them, for Kolreuter and Gartner ^^ found that when two species were
crossed, if either one was variable, the offspring were rendered
variable.

Summary. — From the facts given in this chapter, we may
conclude that the variability of organic beings under domes-
tication, although so general, is not an inevitable contingent
on life, but results from the conditions to which the parents
have been exp)0sed. Changes of any kind in the conditions
of life, even extremely slight changes, often suffice to cause
variability. Excess of nutriment is perhaps the most efficient
single exciting cause. Animals and plants continue to be
variable for an immense period after their first domestication ;
but the conditions to which they are exposed never long
remain quite constant. In the course of time they can be
habituated to certain changes, so as to become less variable ;
and it is possible that when first domesticated they may have
been even more variable than at present. There is good
evidence that the power of changed conditions accumulates ;
so that two, three, or more generations must be exposed to
new conditions before any effect is visible. The crossing of
distinct forms, which haA^e already become variable, increases
in the offspring the tendency to further variabilit}^ by the
unequal commingling of the characters of the two parents, by
the reajijoearance of long-lost characters, and by the appear-
ance of absolutely new characters. Some variations are in-
duced by the direct action of the surrounding conditions ob

" 'Dritte Fortsetzung,' &c., s. 123; ' Bastarderzeugung,' s. 249.

..'HAI-. XXll. CAUSES OF VARIABILITY. 259

the whole organisation, or on certain parts alone ; other
variations appear to be induced indirectly through the re-
productive system being affected, as we know is often the
case with various beings, which when removed from their
natural conditions become sterile. The causes which induce
variability act on the mature organism, on the embryo, and,
probably, on the sexual elements before impregnation has
been effected.

260 DEFINITE ACTION OF THE Chap. XXILl.

CHAPTER XXIII.

DIRECT AND DEFINITE ACTION OP THE EXTERNAL CONDITIONS OF

LIFE.

BLIGHT MODIFICATIONS IX 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 THE INOCULATION OF POISON — LAND-
SHELLS — MODIFICATIONS OP ORGANIC BEINGS IN A STATE OP NATURE
THROUGH THE DEFINITE ACTION OF EXTERNAL CONDITIONS — COMPARISON
OF AMERICAN AND EUROPEAN TREES — GALLS — EFFECTS OF PARASITIC
FUNGI — CONSIDE RATIONS OPPOSED TO THE BELIEF IN THE POTENT
INFLUENCE OF CHANGED EXTERNAL CONDITIONS — PARALLEL SERIES OP
VARIETIES — AMOUNT OP VARIATION DOES NOT CORRESl'OND WITH THE
DEGREE OF CHANGE IN THE CONDITIONS — BUD-VARIATION — MONSTROSI-
TIES PRODUCED BY UNNATURAL TREATMENT — SUMMARY.

If we ask ourselves why this or that character has been modi-
fied under domestication, we are, in most cases, lost in utter
darkness. Many naturalists, especially of the French school,
attribute every modification to the " moude ambiant," that is,
to changed climate, with all its diversities of heat and cold,
dampness and dryness, light and electricity, to the nature of
the soil, and to varied kinds and amount of food. By the
term definite action, as used in this chapter, I mean an action
of such a nature that, when m?iny individuals of the same
variety are exposed during several generations to any par-
ticular change in their conditions of life, all, or nearly all the
individuals, are modified in the same manner. The effects of
habit, or of the increased use and disuse of various organs,
might have been included under this head ; but it will be con-
venient to discuss this subject in a separate chapter. B}'' the
term indefinite action I mean an action which causes one in-
dividual to vary in one way and another individual in another
wsij, as we often see with plants and animals after they have
been subjected for some generations to changed conditions of
life. But we know far too little of the causes and laws of

Chap XXlII. CONDITIONS OF LIFE. 261

variation to make a sound classification. The action of
changed conditions, whether leading to definite or indefinite
results, is a totally distinct consideration from the eifects of
selection ; for selection depends on the preservation by man
of certain individuals, or on their survival under various and
complex natural circumstances, and has no relation whatever
to the primary cause of each particular variation.

I will first give in detail all the facts which I have been
able to collect, rendering it probable that climate, food, &c.,
have acted so definitely and powerfully on the organisation of
our domesticated productions, that new sub-varieties or races
have been thus formed without the aid of selection by man or
nature. I will then give the facts and considerations opposed
to this conclusion, and finally we will weigh, as fairly as we
can, the evidence on both sides.

When we reflect that distinct races of almost all our domes-
ticated animals exist in each kingdom of Europe, and formerly
even in each district of England, we are at first strongly
inclined to attribute their origin to the definite action of the
physical conditions of each country; and this has been the
conclusion of many authors. But we should bear in mind
that man annually has to choose which animals shall be pre-
served for breeding, and which shall be slaughtered. We
have also seen that both methodical and uncon.-cious selection
were formerly practised, and are now occasionally practised
by the most barbarous races, to a much greater extent than
might have been anticipated. Hence it is difficult to judge
how far differences in the conditions between, for instance,
the several districts in England, have sufficed to modify the
breeds which have been reared in each. It may be argued
that, as numerous wild animals and plants have ranged
during many ages throughout Great Britain, and still retain
the same character, the difference in conditions between the
several districts could not have modified in a marked manner
the various native races of cattle, sheep, pigs, and horses.
The same difficulty of distinguishing between the effects of
natural selection and the definite action of external conditions
is encountered in a still higher degree when we compare closely
allied species inhabiting two countries, such as North America

262 DEFINITE ACTION OF THE Chap. XXIIL

and Europe, which do not differ greatly in climate, nature of
soil, &c., for in this case natural selection will inevitably and
rigorously have acted during a long succession of ages.

Prof. Weismann has suggested ^ that when a variable
species enters a new and isolated country, although the varia-
tions may be of the same geneial nature as before, yet it is
improbable that they should occur in the same proportional
numbers. After a longer or shorter period, the species will
tend to become nearly uniform in character from the incessant
crossing of the varying individuals ; but owing to the pro-
portion of the individuals varying in different ways not being
the same in the two cases, the final result will be the pro-
duction of two forms somewhat different from one another.
In cases of this kind it would falsely appear as if the con-
ditions had induced certain definite modifications, whereas
they had only excited indefinite variability, but with the
variations in slightly different proportional numbers. This
view may throw some light on the fact that the domestic
animals which formerly inhabited the several districts in
Great Britain, and the half wild cattle lately kept in
several British parks, differed slightly from one another ; for
these animals were prevented from wandering over the whole
country and intercrossing, but would have crossed freely
within each district or park.

From the difficulty of judging how far changed conditions have
caused definite modifications of structure, it will be advisable to
give as large a body of facts as possible, showing that extremely
slight differences wathin the same country, or during different
seasons, certainly produce an appreciable effect, at least on varieties
which are already in an unstable condition. Ornamental flowers are
good for this purpose, as they are highly variable, and are carefully
observed. All floriculturists are unanimous that certain varieties
are affected by very slight differences in the nature of the artificial
compost in which they are grown, and by the natural soil of the
district, as well as by the season. Thus, a skilful judge, in writing
on Carnations and Picotees,^ asks " where can Admiral Curzon be
" seen possessing the colour, size, and strength which it has in
" Derbyshire ? Where can Flora's Garland be found equal to those
" at Slough ? Where do high-coloured flowers revel better than at

^ ' Ueber den Einflnss der Isolirung ^ 'Gardener's Chronicle,* 1853, p

auf die Artbildune.' 1 872. 183.

Chap. XXIII. CONDITIONS OF LIFE. 263

*' Woolwicli and Bii*mingham ? Yet in no two of these districts do
" the same varieties attain an equal degree of excellence, although
*' each may be receiving the attention of the most skilful cultivators.'*
The same writer then recommends every cultivator to keep five
different kinds of soil and manure, " and to endeavour to suit the
" respective appetites of the plants you are dealing with, for without
*' such attention all hope of general success will be vain." So it is
with the Dahlia^ : the Lady Cooj^er rarely succeeds near London, but
does admirably in other districts; the reverse holds good with other
varieties; and again, there are others which succeed equally well
in various situations. A skilful gardener * states that he procured
cuttings of an old and well-known variety (pulchella) of Verbena,
which from having been propagated in a different situation presented
a slightly different shade of colour ; the two varieties were after-
wards multiplied by cuttings, being carefully kept distinct ; but in
the second year they could hardly be distinguished, and in the third
year no one could distinguish them.

The nature of the season has an especial influence on certain
varieties of the Dahlia: in 1841 two varieties were pre-eminently
good, and the next year these same two were pre-eminently bad.
A famous amateur^ asserts that in 1861 many varieties of the Eose
came so untrue in character, " that it was hardly possible to recog-
" nise them, and the thought was not seldom entertained that the
" grower had lost his tally." The same amateur ^ states that in 1862
two-thirds of his Auriculas produced central trusses of flowers, and
such trusses are liable not to keep true ; and he adds that in some
seasons certain varieties of this plant all prove good, and the next
season all prove bad ; whilst exactly the reverse happens with other
varieties. In 1845 the editor of the ' Gardener's Chronicle ' ^ remarked
how singular it was that this year many Calceolarias tended to
assume a tubular form. With Heartsease * the blotched Sf irts do not
acquire their proper character until hot weather sets in ; whilst other
varieties lose their beautiful marks as soon as this occurs.

Analogous facts have been observed with leaves: Mr. Beaton
asserts^ that he raised at Shrubland, during six years, twenty thousand
seedlings from the Punch Pelargonium, and not one had variegated
leaves ; but at Surbiton, in Surrey, one-third, or even a greater pro-
portion, of the seedlings from this same variety were more or less
variegated. The soil of another district in Surrey has a strong ten-
dency to cause variegation, as appears from information given me
by Sir F. Pollock. Verlot ^" states that the variegated strawberry

* Mr. VVildman, * Floricultural ^ Ibid., 1862, p. 83.

Soc.,' Feb. 7, 1843, reported in ' Gard. ^ ' Gard. Chron.,' 1845, p. 660.

Chron.,' 1843, p. 86. » Ibid., 1863, p. 628.

* Mr. RobsoD, in' Journal of Horti- * ' Journal of Hort.,' 1861, pp. 64^
culture,' Feb. 13th, 1866, p. 122. 309.

* 'Journal of Horticulture,' 1861, *<* ' Des Varietes,' &c., p. 76.
p. 24.

261 DEFINITE ACTION OF THE Chap. XXIIl

retains its character as long as grown in a dryish soil, but soon
loses it when planted, in fresh and humid soil. Mr. Salter, who is
well known for his success in cultivating variegated plants, informs
me that rows of strawberries were planted in his garden in 1859, in
the usual way ; and at various distances in one row, several plants
simultaneously became variegated; and what made the casp. more ex-
traordinary, all were variegated in precisely the same manner. These
plants were removed, but during the three succeeding years other
plants in the same row became variegated, and in no instance were
the plants in any adjoining row affected.

The chemical qualities, odours, and tissues of plants are oftctn
modified by a change which seems to us slight. The Hemlock is
said not to yield conicine in Scotland. The root of the Aconitum
liupeUus becomes innocuous in frigid climates. The medicinal pro-
perties of the Digitalis are easily affected by culture. As the FiUacia
lentiscus grows abundantly in the South of France, the climate must
suit it, but it yields no mastic. The Laurus sassafras in Europe
loses the odour proper to it in North America.^^ Many similar facts
could be given, and they are remarkable because it might have been
thought that definite chemical compounds would have been little
liable to change either in quality or quantity.

The wood of the American Locust-tree (Bohinut) when grown in
England is nearly worthless, as is that of the Oak-tree when gro^^ n
at the Cape of Good Hope.^^ Hemp and flax, as I hear from Dr.
Falconer, flourish and yield plenty of seed on the plains of India,
but their fibres are brittle and useless. Hemp, on the other hand,
fails to produce in England that resinous matter which is so largely
used in India as an intoxicating drug.

The fruit of the Melon is greatly influenced by slight differences
in culture and climate. Hence it is generally a better plan,
according to Naudin, to improve an old kind than to introduce a
new one into any locality. The seed of the Persian Melon pro-
duces near Paris fruit inferior to the poorest market kinds, but at
Bordeaux yields delicious fruit.^^ Seed is annually brought from
Thibet to Kashmir,^* and produces fruit weighing from four to ten
pounds, but plants raised next year from seed saved in Kashmir
give fruit weighing only from two to three pounds. It is well known
that American varieties of the Apple produce in their native
land magnificent and brightly-coloured fruit, but these in England
are of poor quality and a dull colour. In Hungary there are many

^» Engel, 'Sur les Prop. Medicales 'Gardener's Chronicle/ 1849, p. 355;

des Plantes,' 1860, pp. 10, 25. On 1862, p. 1123.
changes in the odours of plants, see ^^ Hooker, ' Flora Indica,' p. 32.

Ds libert's Experiments, quoted by ^^ Naudin, ' Annales des Sc. Nat.,*

Bejkman, ' Inventions,* vol. ii. p. 344; 4th series, Bot., torn, xi., 1859, p. 81.

and Nees, in Ferussac, * Bull, des Sc. ' Gardener's Chronicle,' 1859, p. 464.
Nat.,' 1824, torn. i. p. 60. With i* Moorcroft's ' Travels,' &i-., vol

respect to the rhubarb, &c., see also ii p. 143.

Chap. XXUL CONDITIONS OF LIFE. 2(55

varieties of the kidney-bean, remarkable for the beauty of their
seeds, but the Rev. M. J. Berkeley ^^ found that their beauty could
hardly ever be preserved in England, and in some cases the colour
was greatly changed. We have seen in the ninth chapter, with
respect to wheat, what a remarkable effect transportal from the
north to the south of France, and conversely, produced on the
weight of the grain.

When man can perceive no change in plants or animals
which have been exposed to a new climate or to different
treatment, insects can sometimes perceive a marked change,
A cactus has been imported into India from Canton, Manilla
Mauritius, and from the hot-houses of Kew, and there is like- -
wise a so-called native kind which was formerly introduced
from South. America ; all these plants belong to the same
species and are alike in appearance, but the cochineal insect
flourishes only on the native kind, on which it thrives
prodigiously.^*' Humboldt remarks^'' that white men " born
in the torrid zone walk barefoot with impunity in the same
apartment where a European, recently landed, is exposed to
the attacks of the Pulex penetrans.'^ This insect, the too well-
known chigoe, must therefore be able to perceive what the
most delicate chemical analysis fails to discover, namely, a
difference between the blood or tissues of a European and
those of a white man born in the tropics. But the discern-
ment of the chigoe is not so surprising as it at first appears ;
for according to Liebig^^ the blood of men with different
complexions, though inhabiting the same country, emits a
different odour.

Diseases peculiar to certain localities, heights, or climates, may be
here briefly noticed, as showing the influence of external circum-
stances on the human body. Diseases confined to certain races of
man do not concern us, for the constitution of the race may play
the more important part, and this may have been determined by
unknown causes. The Plica Polonica stands, in this respect, in a

^' 'Gardener's Chronicle,' 1861, p. has been confirmed by Karsten

1113. (' Beitrag zur Kenntniss der Rhyn-

^^ Royle, ' Productive Resources of choprion :' Moscow, 1864, s. 39), and

India,' p. 39. by others.

^^ ' Personal Narrative,' Eng. trans- ** 'Organic Chemistry,' Eng. trans-

lat., vol. V. p. 101. This statement lat., 1st edit., p. 369.

266 DEFINITE ACTION OF THE Chap. XXIIl

nearly intermediate position ; for it rarely affects Germans, who in-
habit the neighbourhood of the Vistula, where so many Poles are
grievously affected ; neither does it affect Russians, who are said
to belong to the same original stock as the Poles.^^ The eleva-
tion of a district often governs the appearance of diseases; in Mexico
the yellow fever does not extend above 924 metres ; and in Peru,
people are affected with the verugas only between 600 and 1600
metres above the sea; many other such cases could be given. A
peculiar cutaneous complaint, called the Bouton d'Alep, affects
in Aleppo and some neighbouring districts almost every native
infant, and some few strangers ; and it seems fairly well established
that this singular complaint depends on drinking certain waters.
In the healthy little island of St. Helena the scarlet-fever is dreaded
like the Plague; analogous facts have been observed in Chili and
Mexico.^" Even in the different departments of France it is found
that the various infirmities which render the conscript unfit for
serving in the army, prevail M'ith remarkable inequality, revealing,
as Boudin observes, that many of them are endemic, which other-
wise would never have been suspected.-^ Any one who will study
the distribution of disease will be struck with surprise at what
slight differences in the surrounding circumstances govern the
nature and severity of the complaints by which man is at least
temporarily affected.

The modifications as yet referred to are extremely slight, and in
most cases have been caused, as far as we can judge, by equally slight
differences in the conditions. But such conditions acting during
a series of generations would perhaps produce a marked effect.

"With plants, a considerable change of climate sometimes produces
a conspicuous result. I have given in the ninth chapter the most
remarkable case known to me, namely, that of varieties of maize,
which were greatly modified in the course of only two or three
generations when taken from a tropical country to a cooler one, or
conversely. Dr. Falconer informs me that he has seen the English
llibston-pippin apple, a Himalayan oak, Prunus andPyrus, all assume
in the hotter parts of India a fastigate or pyramidal habit ; and this
fact is the more interesting, as a Chinese tropical species of Pyrus
naturally grows thus. Although in these cases the changed manner
of growth seems to have been directly caused by the great heat, we
know that many fastigate trees have originated in their temperate
homes. In the Botanic Gardens of Ceylon the apple-tree ^^ "sends
out numerous runners under ground, which continually rise into
small stems, and form a growth around the parent-tree." The
varieties of the cabbage which produce heads in Europe fail to do so

• Pj ichard, * Phys. Hist, of Man- taken from Dr. Boudin's * Gdographie

kbd,' 1851, vol. i. p. 155. et Statistique Medicale,' 1857, torn.

'■'^ Darwin, 'Journal of Researches,' i. pp. xliv. and Hi.; torn. ii. p. 315.
1845, p. 434. " <Cevlon,' by Sir J. E. Tennent,

*' These statements on disease are vol. i., 1859, p. 89.

Chap. XXIII.

CONDITIONS OF LIFE.

2G7

in certain tropical countries.^^ Tlie Rhododendron ciHatum produced
at Kew flowers so much larger and paler-coloured than those which
it bears on its native Himalayan mountain, that Dr. Hooker ^^ would
hardly have recognised the species by the flowers alone. Many
similar facts with respect to the colour and size of flowers could
be given.

The experiments ol Yilmorin and Buckman on carrots and
parsnips prove that abundant nutriment produces a definite and
inheritable effect on the roots, with scarcely any change in other
parts of the plant. Alum directly influences the colour of the
flowers of the Hydrangea.'^^ Dryness seems generally to favour the
hairiness or villosity of plants. Gartner found that hybrid
Verbascums became extremely w^ooUy when grown in pots. Mr,
Masters, on the other hand, states that the Opuntia leucotricha "is
" well clothed with beautiful white hairs when grown in a damp
" heat, but in a dry heat exhibits none of this peculiarity." ^^ Slight
variations of many kinds, not worth specifying in detail, are retained
only as long as plants are grown in certain soils, of which Sageret-'
gives some instances from his own experience. Odart, who insists
strongly on the permanence of the varieties of the grape, admits^*
that some varieties, when grown under a different climate or treated
difiierently, vary in a slight degree, as in the tint of the fruit and in
the period of ripening. Some authors have denied that grafting
causes even the slightest difference in the scion ; but there is
sufficient evidence that the fruit is sometimes slightly affected in
size and flavour, the leaves in duration, and the flowers in appear-
ance.^

There can be no doubt, from the facts given in the first
chapter, that European dogs deteriorate in India, not only in
their instincts but in structure ; but the changes which they undergo
are of such a nature, that they may be partly due to reversion to a
primitive form, as in the case of feral animals. In parts of India the
turkey becomes reduced in size, " with the pendulous appendage over
the beak enormously developed."^" We have seen how soon the wild
duck, when domesticated, loses its true character, from the effects of
abundant or changed food, or from taking little exercise. From the
direct action of a humid climate and poor pasture the horse rapidly
decreases in size in the Falkland Islands. From information which

2' Godron. ' De I'Espfece,' torn. ii.
p. 52.

^* ' Journal of Horticultural Soc.,'
rol. vii., 18")2, p. ] 17.

25 ' Journal of Hort. Soc.,' vol. i. p.
160.

2'* See Lecoq, on the Villosity of
Plants, ' Geograph. Bot.,' torn. iii. pp.
287, 291; Gkrtner, ' Bastarderz.,' s.
261 ; Mr. Masters, on the Opuntia,
in * Gard. Chronicle,' 1846, p. 444.

" 'Pom. Phys.,'p. 136.

2» ' Ampelographie,' 1849, p. 19.

29 Gartner, ' Bastarderz.,' s. 606,
has collected nearly all recorded facts.
Andrew Knight (in 'Transact, Hort.
Soc.,' vol. ii. p. 160) goes so far as to
maintain that few varieties are abso-
lutely permanent in character when
propagated by buds or grafts.

^° Mr. Blyth, in ' Annals and Mag
of Nat. Hist.,' vol. xx., 1847, p. 391.

268 DEFINITE ACTION OF THE Chap. XXIIL

I have received, this seems likewise to be the case to a certain
extent with sheep in Australia.

Climate definitely influences the hairy covering of animals; in
the West Indies a great change is i)roduced in the fleece of sheep,
in about three generations. Dr. Falconer states ^^ that the Thibet
mastiff and goat, when brought down from the Himalaya to
Kashmir, lose their fine wool. At Angora not only goats, but
shepherd-dogs and cats, have fine fleecy hair, and Mr. Ainsworth ^^
attributes the thickness of the fleece to the severe winters, and its
silky lustre to the hot summers. Burnes states positively ^^ that the
Karakool sheep lose their peculiar black curled fleeces when removed
into any other country. Even within the limits of England, I have
been assured that the wool of two breeds of sheep was slightly
changed by the flocks being pastured in different localities.^* It
has been asserted on good authority ^ that horses kept during
several years in the deep coal-mines of Belgium become covered
with velvety hair, almost like that on the mole. These cases
probably stand in close relation to the natural change of coat in
winter and summer. Naked varieties of several domestic animals
have occasionally appeared ; but there is no reason to believe that
this is in any way related to the nature of the climate to which
they have been exposed.^*^

It appears at first sight probable that the increased size, the
tendency to fatten, the early maturity and altered forms of our
improved cattle, sheep, and pigs, have directly resulted from their
abundant supply of food. This is the opinion of many competent
judges, and probably is to a great extent true. But as far as form is
concerned, we must not overlook the more potent influence of
lessened use on the limbs and lungs. We see, moreover, as far as
size is concerned, that selection is apparently a more powerful agent
than a large supply of food, for we can thus only account for the
existence, as remarked to me by Mr. Blyth, of the largest and
smallest breeds of sheep in the same country, of Cochin-China fowls
and Bantams, of small Tumbler and large Kunt pigeons, all kept
together and supplied with abundant nourishment. Nevertheless
there can be little doubt that our domesticated animals have been
modified, independently of the increased or lessened use of parts, by
the conditions to which they have been subjected, without the aid
of selection. For instance. Prof. Riitimeyer ^^ shows that the bones of

21 ' Natural History Review,' 1862, 'Hist. Nat. Gen.,' torn. iii. p. 438.

p. 113. ^* Azara has made some good re-

'2 ' Journal of Roy. Geographical marks on this subject, ' Quadrupedes

3oc.,' vol. ix., 1839, p. 275. du Paraguay,' torn. ii. p. 337. See

'* 'Travels in Bokhara,' vol. iii. p. an account of a family of naked mice

151. produced in England, ' Proc. Zoolog,

2* See also, on the influence of Soc.,' 1856, p. 38.

marshy pastures on the wool, Godron, " ' Die Fauna der Pfahlbauten,

*L'Espece,' torn. ii. p. 22. 1861, s. 15.

'* Isidorft Geotfroy Saint-Hilaire,

Chap. XXIII. CONDITIONS OF LIFE. 269

domesticated quadrupeds can be distinguished from those of wild
animals by the state of their surface and general appearance. It is
scarcely possible to read Nathusius's excellent 'Yorstudien/^^ and
doubt that, with the highly improved races of the pig, abundant
food has produced a conspicuous effect on the general form of tho
body, on the breadth of the head and face, and even on the t^eth,
Nathusius rests much on the case of a purely bred Berkshire pig,
which when two months old became diseased in its digestive organs,
and was preserved for observation until nineteen months old ; at
this age it had lost several characteristic features of the breed, and
had acquired a long, narrow head, of large size relatively to its
small body, and elongated legs. But in this case and in some others
we ought not to assume that, because certain characters are last,
perhaps through reversion, under one course of treatment, therefore
that they were at first directly produced by an opposite treatment.

In the case of the rabbit, which has become feral on the island of
Porto Santo, we are at first strongly tempted to attribute the
whole chauge — the greatly reduced size, the altered tints of the fur,
and the loss of certain characteristic marks — to the definite action
of the new conditions to which it has been exposed. But in all such
cases we have to consider in addition the tendency to reversion to
progenitors more or less remote, and the natural selection of the
finest shades of difference.

The nature of the food sometimes either definitely induces certain
peculiarities, or stands in some close relation with them. Pallas
long ago asserted that the fat-tailed sheep of Siberia degenerate
and lose their enormous tails when removed from certain saline
pastures ; and recently Erman ^^ states that this occurs with the
Kirgisian sheep when brought to Orenburgh.

It is well known that hemp-seed causes bullfinches and certain
other birds to become black. ]Mr. Wallace has communicated to me
some much more remarkable facts of the same nature. The natives
of the Amazonian region feed the common gi*een parrot (Chrysotis
/estiva, Linn.) with the fat of large Siluroid fishes, and the birds
thus treated become beautifully variegated with red and yellow
feathers. In the Malayan archipelago, the natives of Gilolo alter in
an analogous manner the colours of another parrot, namely, the
Lorius garridus, Linn,, and thus produce the Lori rajah or King-
Lory. These parrots in the Malay Islands and South America,
when fed by the natives on natural vegetable food, such as rice and
plaintains, retain their proper colours. Mr. Wallace has, also, re-
corded^" a still more singular fact. " The Indians (of S. America)
*' have a curious art by which they change the colours of the feathers
" of many birds. They pluck out those from the part they wish to
*' paint, and inoculate the fresh wound with the milky secretion
" from the skin of a small toad. The feathers grow of a brilliant

" 'Schweineschadel,' 186+,s. 99. "o A. R. Wallace, 'Travels on th«

'^ 'Travels in Siberia,' Eng. trans- Amazon and Rio Negro/ p. 25:'4.
lat., vol. i. p. 228.

270

DEFINITE ACTION OF THE

Chap. XXUl

" yellow colour, and on being plucked out, it is said, grow again of
" the same colour without any fresh operation."

Bechstein^^ does not entertain any doubt that seclusion from
light affects, at least temporarily, the colours of cage-birds.

It is well known that the shells of land-mollusca are affected by
the abundance of lime in different districts. Isidore Geoffroy Saint-
Hilaire ^^ gives the case of Helix lactea, which has recently been
carried from Spain to the South of France and to the Rio Plata, and
in both countries now presents a distinct appearance, but whether
this has resulted from food or climate is not known. With respect
to the common oyster, Mr. F. Buckland informs me that he can
generally distinguish the shells from different districts; young
oysters brought from Wales and laid down in beds where " natives "
are indigenous, in the short space of two months begin to assume
the " native " character. M. Costa^^ has recorded a much more re-
markable case of the same nature, namely, that young shells taken
from the shores of England and placed in the Mediterranean, at
once altered their manner ofgrowth and formed prominent diverging
rays, like those on the shells of the proper Mediterranean oyster. The
same individual shell, showing both forms of growth, was exhibited
before a society in Paris. Lastly, it is well known that caterpillars
fed on different food sometimes either themselves acquire a dilfei-ent
colour or produce moths differing in colour.^*

It would be travelling beyond my proper limits here to discuss
how far organic beings in a state of nature are definitely modified
by changed conditions. In my ' Origin of Species ' I have given a
brief abstract of the facts bearing on this point, and have shown the
influence of light on the colours of birds, and of residence near the
sea on the lurid tints of insects, and on the succulency of plants.
Mr. Herbert Spencer*^ has recently discussed with much ability
this whole subject on general grounds. He argues, for instance,
that with all animals the external and internal tissues are differently
acted on by the surrounding conditions, and they invariably differ
in intimate structure. So again the upper and lower surfaces of
true leaves, as well as of stems and petioles, when these assume

** ' Naturgeschichte der Stuben-
vogel,' 1840, s. 262,308.

*^ ' Hist. Nat Gen.,' torn. iii. p.
402.

« ' Bull, de la Soc. Imp. d'Accli-
mat.,' torn. viii. p. 351.

** See an account of Mr. Gregson's
experiments on the Ahraxus grossu-
lariata, ' Proc. Entomolog. Soc.,' Jan.
6th, 1862: these experiments have
been confirmed by Mr. Greening, in
' Proc. of the Northern Entomolog.
Soc.,' July 28th, 1862. For the etiects
of food on caterpillars, see a curious
account by M. Michely, in 'Bull, de

la Soc. Imp. d'Acclimat.,' tom. viii. p.
663. For analogous facts from
Dahlbom on Hymenoptera, see West-
wood's ' Modern Class, of Insects,' vol.
ii. p. 98. See also Dr. L. Moller,
' Die Abhangigkeit der Insecten,'
1867, s. 70.

*^ 'The Principles of Biology,' vol.
ii., 1866. The present chapters were
written before I had read Mr. Her-
bert Spencer's work, so that I have
not been able to make so much use of
it as I should otherwise probably
have done.

Chap. XXIII. CONDITIONS OF LIFE. 271

the function and occupy the position of leaves, are differently
circumstanced with respect to light, &c., and apparently in con-
sequence differ in structure. But, as Mr. Herbert Spencer admits,
it is most difficult in all such cases to distinguish between the
effects of the definite action of physical conditions and the accumu-
lation through natural selection of inherited yariations which are
serviceable to the organism, and which have arisen indei)endently
of the definite action of these conditions.

Although, we are not here concerned with the definite
action of the conditions of life on organisms in a state of
nature, I may state that much evidence has been gained
during the last few years on this subject. In the United
States, for instance, it has been clearly proved, , more
esjDCcially by Mr. J. A. Allen, that, with birds, man}'- sjDecies
differ in tint, size of body and of beak, and in length of tail,
in proceeding from the North to the South ; and it ajDpears
that these differences must be attributed to the direct action
of temperature.*^ With respect to plants I will give a some-
what analogous case : Mr. Meehan,''^ has compared twenty-
nine kinds of American trees with their nearest EurojDean
allies, all grown in close proximity and under as nearly as
possible the same conditions. In the American species he
finds, with the rarest exceptions, that the leaves fall earlier in
the season, and assume before their fall a brighter tint ; that
they are less deeply toothed or serrated ; that the buds are
smaller; that the trees are more diffuse in growth and have
fewer branchlets ; and, lastly, that the seeds are smaller— all
in comparison with the corresponding European species. Now
considering that these corresponding trees belong to several
distinct orders, and that they arc adapted to widely different
stations, it can hardly be supposed that their differences are
of any special service to them in the New and Old worlds ;
and if so such differences cannot have been gained through
natural selection, and must be attributed to the long con-
tinued action of a different climate.

^* Professor Weismann comes to other authors on the present subject ;

the same conclusion with respect to lor instance, to Kerner's ' Gute und

certain European butterflies in his schlechte Arten,' 1866.

valuable essay, ' Ueber den Saison- *'' ' Proc. Acad. Nat. Soc. of I*hila«

Dimorphismus,' 1875. I might also delphia,' Jan. 28th, 186'J.
refer to the recent works of several

272 DEFINITE ACTION OF THE Chap. XXIII,

Galls. — Another class of facts, not relating to cultivated
plants, deserves attention. I allude to the production of galls.
Every one knows the curious, bright-red, hairy productions
on the wild rose-tree, and the various different galls produced
by the oak. Some of the latter resemble fruit, with one face
as rosy as the rosiest apple. These bright colours can be of
no service either to the gall-forming insect or to the tree, and
probably are the direct result of the action of the light, in the
same manner as the apples of Nova Scotia or Canada are
brighter coloured than English apples. According to Osten
Sacken's latest revision, no less than fifty-eight kinds of galls
are produced on the several species of oak, by Cyni]3S with its
sub-genera; and Mr. B. D. Walsh"^^ states that he can add
many others to the list. One American species of willow,
the Salix Immilis, bears ten distinct kinds of galls. The leaves
which spring from the galls of various English willows differ
completely in shape from the natural leaves. The young
shoots of junipers and firs, when punctured by certain insects,
yield monstrous growths resembling flowers and fir-cones : and
the flowers of some plants become from the same cause wholl v
changed in appearance. Galls are produced in every quartei-
of the world ; of several sent to me by Mr. Thwaites from
Ceylon, some were as s^'mmetrical as a composite flower
when in bud, others smooth and spherical like a berry ; some
protected by long spines, others clothed with yellow wool
formed of long cellular hairs, others with regularly tufted
hairs. In some galls the internal structure is simple, but in
others it is highly complex ; thus M. Lacaze-Duthiers*^ has
figured in the common ink-gall no less than seven concentric
layers, composed of distinct tissue, namely, the epidermic,
sub -epidermic, spongy, intermediate, and the hard protective
layer formed of curiously thickened woody cells, and, lastly,
the central mass, abounding with starch-granules on which
the larvae feed.

Galls are pioduced by insects of various orders, but the

48 See Mr. B. D. Walsh's excellent 1864, p. 546.

papers in ' Pi'oc. Entoraolog. Soc. ''^ See his admirable ' Histoire des

Philadelphia,' Dec. 1866, p. 284. Galles,' in ' Annal. des Sc. Nat. Bot.,'

With respect to the willow, see ibid., 3rd series, torn, xi.x., 18o3, p. 273.

Chap. XXIII. CONDITIONS OF LIFE. 273

greater number by species of Cynips. It is impossible to read
M. Lacaze-Duthiers' discussion and doubt that the poisonous
secretion of the insect causes the growth of the gall ; and every
one knows how virulent is the poison secreted by wasps and
bees, which belong to the same group with Cynips. Galls
grow with extraordinary rapidity, and it is said that they
attain their full size in a few days ; ^° it is certain that they
are almost completely develoj)ed before the larvae are batched.
Considering that many gall-insects are extremely small, the
drop of secreted poison must be excessively minute ; it pro-
bably acts on one or two cells alone, which, being abnor-
mally stimulated, rapidly increase by a process of self-division.
Galls, as Mr. Walsh^^ remarks, afford good, constant, and
definite characters, each kind keeping as true to foim as does
any independent organic being. This fact becomes still more
remarkable when we hear that, for instance, seven out of the
ten different kinds of galls produced on Salix humilis are formed
by gall-gnats {Cecidomyidce) which " though essentially dis-
" tinct species, yet resemble one another so closely that in
" almost all cases it is difficult, and in most cases impossible,
" to distinguish the full-grown insects one from the other."^-
For in accordance with a wide-spread analogy we may safely
infer that the poison secreted by insects so closely allied
would not differ much in nature ; yet this slight difference is
sufficient to indiK e widely different results. In some few
cases the same specie.s of gall-gnat produces on distinct species
of willows galls which cannot be distinguished ; the Cynijjs
fecundatrix, also, has been known to produce on the Turkish
oak, to which it is not properly attached, exactly the same
kind of gall as on the European oak.^^ These latter facts
apparently prove that the nature of the poison is a more
powerful agent in determining the form of the gall than the
specific character of the tree which is acted on.

As the poisonous secretion of insects belonging to various
orders has the special power of affecting the growth of various

^0 KirbyandSpence's 'Entomology,' " Mr. B. D.Walsh, ibid., p. 633,

1818, vol. i. p. 450; Lacaze-Duthiers, and Dec. 1866, p. 275.
ibid., p. 284. " Mr. B. D. Walsh, ibid., 1864, pj)

"'Proc. Entomolog. Soc. Phila- 545, 411, 495 ; and Dec. 1866, p. 27«

delphia,' 1864, p. 558. See also Lacaze-Duthiers.

274 DEFINITE ACTION OF THE Chap. XXIII.

plants ; as a slight difference in the nature of the poison suffices
to produce widely different results ; and lastly, as we know
that the chemical compounds secreted by plants are eminently
liable to be modified by changed conditions of life, we may
believe it possible that various parts of a plant might be
modified through the agency of its own altered secretions.
Compare, for instance, the mossy and viscid calyx of a moss-
rose, which suddenly appears through bud-variation on a
Provence- rose, with the gall of red moss growing from the
inoculated leaf of a wild rose, with each filament symmetri-
cally branched like a microscopical spruce-fir, bearing a
glandular tip and secreting odoriferous gummy matter.^* Or
compare, on the one hand, the fruit of the peach, with its
hairy skin, fleshy covering, hard shell and kernel, and on the
other hand one of the more complex galls with its epidermic,
spongy, and woody layers, surrounding tissue loaded with
starch granules. These normal and abnormal structures
manifestly present a certain degree of resemblance. Or,
again, reflect on the cases above given of parrots which have
had their plumage brightly decorated through some change
in their blood, caused by having been fed on certain fishes, or
locally inoculated with the poison of a toad. I am far from
wishing to maintain that the moss-rose or the hard shell of
the peach-stone or the bright colours of birds are actually due
to any chemical change in the sap or blood ; but these cases of
galls and of parrots are excellently adapted to show us how
powerfully and singularlj^ external agencies may affect struc-
ture. With such facts before us, we need feel no surprise
at the appearance of any modification in any organic being.

I may, also, here allude to the remarkal^le effects which parasitic
fungi sometimes produce on plants. Eeissek^^ has described a
Thesium, affected by an CEcidium, which was greatly modified, and
assumed some of the characteristic features of certain allied species,
or even genera. Suppose, says Eeissek, " the condition originally
" caused by the fungus to become constant in the course of time,
" the plant would, if found growing wild, be considered as a distinct
" species or even as belonging to a new genus." I quote this

^* Lacaze-Duthiers, ibid., pp. 325, by Dr. M. T. Masters, Royal Institu*
328. tion, March IGth, 18()0.

" 'Linnsea,' vol. xvii., 1843 ; quoted

Chap. XXTTT. CONDITIONS OF LIFZ. 275

remark to sliow how profoundly, yet in liow natural a manner, this
plant must have been moclitied by the parasitic fungus. Mr.
Meehan^^ also states that three species of Euphorbia and Fortulaca
olereacea, which naturally grow prostrate, become erect when they
are attacked by the CEcidium. Euphoy-'hia maculata in this case also
becomes nodose, with the branchlets comparatively smooth and the
leaves modified in shape, approaching in these respects to a distinct
species, namely, the K hyper icifolia.

Facts and Considerations opposed to the belief that the Conditions
of Life act in a potent manner in causing definite Modijications
of Structure,

I have alluded to the slight differences in species naturally
living in distinct countries under different conditions ; and
such differences we feel at first inclined to attribute, probably
often with justice, to the definite action of the surrounding con-
ditions. But it must be borne in mind that there exist many
animals and plants which range widely and have been exposed
to great diversities of climate, yet remain uniform in character.
Some authors, as previously remarked, account for the varie-
ties of our culinary and agricultural plants by the definite
action of the conditions to which they have been exposed in
the different parts of Great Britain ; but there are about 200
plants ^"^ which are found in every single English county ; and
these plants must have been exposed for an immense period
to considerable differences of climate and soil, yet do not
differ. So, again, some animals and plants range over a large
jDortion of the world, yet retain the same character.

Notwithstanding the facts previously given on the occurrence of
highly peculiar local diseases and on the strange modifications of
structure in plants caused by the inoculated poison of insects, and
other analogous cases; still there are a multitude of variations — ■
such as the modified skull of the niata ox and bulldog, the long
horns of Caffre cattle, the conjoined toes of the solid-hoofed swine,
the immense crest and protuberant skull of Polish fowls, the crop
of the pouter-pigeon, and a host of other such cases — which we can
hardly attribute to the definite action, in the sense before specified,
of the external conditions of life. No doubt in every case there
must have been some exciting cause ; but as we see innumerable

56

' Proc. Acad. Nat. Sc, Philadcl- " Hewett C. Watson, ' Cybele

phia,' June 16, 1874, and July 23, Britannica,' vol. i., 1847, p. 11.
1875.

276 DEFINITE ACTION OF THE Chap. XXIII.

individuals exposed to nearly the same conditions, and one alone is
affected, we may conclude that the constitution of the individual is
of far higher importance than the conditions to which it has been
exposed. It seems, indeed, to be a general rule that conspicuous
variations occur rarely, and in one individual alone out of millions,
though all may have been exposed, as far as we can judge, to nearly
the same conditions. As the most strongly marked variations
graduate insensibly into the most trifling, we are led by the same
train of thought to attribute each slight variation much more to
innate differences of constitution, however caused, than to the
definite action of the surrounding conditions.

We are led to the same conclusion by considering the cases,
formerly alluded to, of fowls and pigeons, which have varied and
will no doubt go on var^'ing in directly opposite ways, though kept
during many generations under nearly the same conditions. Some,
for instance, are born with their beaks, wings, tails, legs, &c., a
little longer, and others with these same parts a little shorter. By
the long-continued selection of such slight individual differences
which occur in birds kej^t in the same aviary, widely different races
could certainly be formed ; and long-continued selection, important
as is the result, does nothing but preserve the variations which arise,
as it appears to us, spontaneously.

In these cases we see that domesticated animals vary in an
indefinite number of particulars, though treated as imiformly as
is possible. On the other hand, there are instances of animals and
plants, which, though they have been exposed to very different
conditions, both under nature and domestication, have varied in
nearly the same manner. Mr. Layard informs me that he has
observed amongst the Caffres of South Africa a dog singularly like
an arctic Esquimaux dog. Pigeons in India present nearly the
same wide diversities of colour as in Europe; and I have seen
chequered and simply barred pigeons, and pigeons with blue and
white loins, from Sierra Leone, Madeira, England, and India. New
varieties of flowers are continually raised in different parts of Great
Britain, but many of these are found by the judges at our exhibitions
to be almost identical with old varieties. A vast number of new
fruit-trees and culinary vegetables have been produced in North
America : these differ from European varieties in the same general
manner as the several varieties raised in Europe differ from one
another ; and no one has ever pretended that the climate of America
has given to the many American varieties any general character by
which they can be recognised. Nevertheless, from the facts pre-
viously advanced on the authority of Mr. Meehan with respect to
American and European forest-trees it would be rash to affirm that
varieties raised in the two countries would not in the course of
ages assume a distinctive character. Dr. M. Masters has recorded a
striking fact *** bearing on this subject: he raised numerous plants

" 'Gardener's Chronicle,' 1857, p. 629.

Chap. XXIII. CONDITIONS OF LIFE. 277

of TTyhhcus syriacus from seed collected in South Caroliua and the
Holy Land, where the parent-plants must have been exposed to
considerably different conditions; yet the seedlings from both
localities broke into two similar strains, one with obtuse leaves and
purple or crimson flowers, and the other with elongated leaves and
more or less pink flowers.

We may, also, infer the prepotent influence of the constitution of
the organism over the definite action of the conditions of life, from
the several cases given in the earlier chapters of parallel series of
varieties, — an important subject, hereafter to be more fully dis-
cussed. Sub-varieties of the several kinds of wheat, gourds, peaches,
and other plants, and to a limited extent sub-varieties of the fowl,
pigeon, and dog, have been shown either to resemble or to differ
from one another in a closely corresponding or parallel manner.
In other cases, a variety of one sjDecies resembles a distinct species ;
or the varieties of two distinct species resemble one another.
Although these parallel resemblances no doubt often result from
reversion to the former characters of a common progenitor ; yet in
other cases, when new characters first appear, the resemblance must
be attributed to the inheritance of a similar constitution, and con-
sequently to a tendency to vary in the same manner. We see
something of a similar kind in the same monstrosity appearing and
reappearing many times in the same species of animal, and, as Dr.
Maxvvell Masters has remarked to me, in the same species of plant.

We may at least conclude, that the amount of modification
which animals and plants have undergone under domestication
does not correspond with the degree to which they have been
subjected to changed circumstances. As we know the parent-
age of domesticated birds far better than of most quadrupeds,
we will glance through the list. The pigeon h-is varied iu
Europe more than almost any other bird ; yet it is a native
species, and has not been exposed to any extraordinary change
of conditions. The fowl has varied equally, or almost equally,
with the pigeon, and is a native of the hot jungles of India.
Neither the peacock, a native of the same country, nor the
guinea-fowl, an inhabitant of the dry deserts of Africa, has
varied at all, or only in colour. The turkey, from Mexico,
has varied but little. The duck, on the other hand, a native
of Europe, has j^elded some well-marked races ; and as this
is an aquatic bird, it must have been subjected to a far more
serious change in its habits than the pigeon or even the fowl,
which nevertheless have varied in a much higher degree.
The goose, a native of Europe and aquatic like the duck, has
34

278 DEFINITE ACTION OF TUE Chap. XXIII.

varied less tlian any other domesticated bird, except tlie
peacock.

Bud-variation is, also, important under our present point of
vievv^. In some few cases, as v^hen all the eyes on the same
tuber of the potato, or all the fruit on the same plum-tree, or
all the flowers on the same plant, have suddenly varied in the
same manner, it might be argued that the variation had been
definitely caused by some change in the conditions to which
the plants had been exposed; yet, in other cases, such an
admission is extremely difficult. As new characters some-
times apj)ear by bud-variation, which do not occur in the
parent-species or in any allied species, we may reject, at least
in these cases, the idea that they are due to reversion. Now
it is well worth while to reflect maturely on some striking
case of bud -variation, for instance that of the peach. This
tree has been cultivated by the million in various parts of the
world, has been treated differently, grown on its own roots
and grafted on various stocks, planted as a standard, trained
against a wall, or under glass ; yet each bud of each sub-
variety keeps true to its kind. But occasionally, at long
intervals of time, a tree in England, or under the widely
different climate of Virginia, produces a single bud, and this
yields a branch which ever afterwards bears nectarines.
Nectarines differ, as every one knows, from peaches in their
smoothness, size, and flavour ; and the difference is so great
that some botanists have maintained that they are speci-
fically distinct. So permanent are the characters thus
suddenly acquired, that a nectarine produced by bud-variation
has propagated itself by seed. To guard against the supposi-
tion that there is some fundamental distinction between bud
and seminal variation, it is well to bear in mind that
nectarines have likewise been produced from the stone of the
peach ; and, reversely, peaches from the stone of the nectarine.
ISow is it possible to conceive external conditions more
closely alike than those to which the buds on the same tree
are exposed ? Yet one bud alone, out of the many thousands
borne by the same tree, lias suddenly, without any apparent
cause, produced a nectarine But the case is even stronger
than this, for the same flower -bud has yielded a fruit, one-

Chap. XXIII. CONDITIONS OF LIFE. 279

half or one-quarter a nectarine, and the other half or three-
quarters a peach. Again, seven or eight varieties of the
peach have yielded by bud-variation nectarines : the nectarines
thus produced, no doubt, difi'er a little from one another ;
but still they are nectarines. Of course there must be
some cause, internal or external, to excite the peach-bud to
change its nature; but I cannot imagine a class of facts
better adapted to force on our minds the conviction that
what we call the external conditions of life are in many cases
quite insignificant in relation to any particular variation, in
comparison with the organisation or constitution of the being
which varies.

It is known from the labours of Geoffrey Saint-Hilaire, and
recently from those of Dareste and others, that eggs of the
fowl, if shaken, placed upright, perforated, covered in part
with varnish, &c., produce monstrous chickens. Now these
monstrosities may be said to be directly caused by such
unnatural conditions, but the modifications thus induced are
not of a definite nature. An excellent observer, M. Camille
Dareste,^^ remarks " that the various species of monstrosities
" are not determined by specific causes ; the external agencies
" which modify the development of the embr3^o act solely in
"causing a perturbation — a perversion in the normal course of
" development." He compares the result to what we see in
illness : a sudden chill, for instance, affects one individual
alone out of many, causing either a cold, or sore-throat, rheu-
matism, or inflammation of the lungs or pleura. Contagious
matter acts in an analogous manner.^" We may take a still
more specific instance : seven pigeons were struck hy rattle-
snakes :^^ some suffered from convulsions ; some had their
blood coagulated, in others it was perfectly fluid ; some
showed ecchymosed spots on the heart, others on the intestines,
&c. ; others again showed no visible lesion in any organ. It
is well known that excess in drinking causes different diseases

^® * Memoire sur la Production his ' Vie, Travaux,' &c., 18+7, p. 290.
Artificielle des Monstruosites,' 18'^2, ^^ P^get, ' Lectures on Surgical

pp. 8-r2; ' Recherches sur les Conai- Pathology,' 1853, vol. i. p. 48.).
t'ons, &c., chez les Monstres,' 1863, ^' ' Researches upon the Venom of

p. b. An abstract is given of the Rattle-snake,' Jan. 1861, by Dr.

Geoffroy's Experiments by his son, in Mitchell, p. 67.

280 DEFINITE ACTION OF THE Chap. XXIIl

in different men ; but in the tropics the effects of intemper-
ance differ from those caused in a cold climate ; ^^ and in this
case we see the definite influence of 0]3posite conditions.
The foregoing facts apparently give us as good an idea as
we are likely for a long time to obtain, how in many cases
external conditions act directl}^ though not definitely, in
causing modifications of structure.

Summary. — There can be no doubt, from the facts given in
this chapter, that extremely slight changes in the conditions
of life sometimes, probably often, act in a definite manner
on our domesticated productions ; and, as the action of
changed conditions in causing indefinite variability is accumu-
lative, so it may be with their definite action. Hence
considerable and definite modifications of structure probably
follow from altered conditions acting during a long series of
generations. In some few instances a marked effect has been
produced quickly on all, or nearly all, the individuals which
have been exposed to a marked change of climate, food, or
other circumstance. This has occurred with EurojDcan men in
the United States, with European dogs in India, with horses
in the Falkland Islands, apparently with various animals at
Angora, with foreign oysters in the Mediterranean, and with
maize transported from one climate to another. We have
seen that the chemical compounds of some plants and the
state of their tissues are readily affected by changed condi-
tions. A relation apparently exists between certain characters
and certain conditions, so that if the latter be changed the
character is lost — as with the colours of flowers, the state of
some culinary plants, the fruit of the melon, the tail of
fat- tailed sheep, and the peculiar fleeces of other sheep.

The production of galls, and the change of plumage in parrots
when fed on peculiar food or when inoculated by the poison
of a toad, prove to us what great and mysterious changes in
structure and colour, may be the definite result of chemical
changes in the nutrient fluids or tissues.

We now almost certainly know that organic beings in a

•' Mr. So(igwick, in ' British and Foreign Medico-Chirurg. Review,' Julv
1863, p. 175."

Chap. XXIIL CONDITIONS OF LIFE. 281

state of nature may be modified in various definite \vays by
the conditions to which they have been long exposed, as in
the case of the birds and other animals in the northern and
southern United States, and of American trees in comparison
with their representatives in Europe. But in many cases it
is most difficult to distinguish between the definite result of
changed conditions, and the accumulation through natural
selection of indefinite variations which have prove serviceable.
If it profited a plant to inhabit a humid instead of an arid
station, a fitting change in its constitution might possibly
result from the direct action of the environment, though we
have no grounds for believing that variations of the right
kind would occur more frequently with plants inhabiting a
station a little more humid than usual, than with other plants.
Whether the station was unusually dry or humid, variations
adapting the plant in a slight degree for directly opposite
habits of life would occasionally arise, as we have good reason
to believe from what we actually see in other cases.

The organisation or constitution of the being which is
acted on, is generally a much more important element than
the nature of the changed conditions, in determining the
nature of the variation. We have evidence of this in the
appearance of nearly similar modifications under different
conditions, and of diff'erent modifications under apparently
nearly the same conditions. We have still better evidence of
this in closely parallel varieties being frequently produced
from distinct races, or even distinct species ; and in the
frequent recurrence of the same monstrosity in the same
species. We have also seen that the degree to which
domesticated birds have varied, does not stand in any close
relation with the amount of change to which they have been
subjected.

To recur once again to bud-variations. When we reflect on
the millions of buds which many trees have produced, before
some one bud has varied, we are lost in wonder as to what
the precise cause of each variation can be. Let us recall the
case given by Andrew Knight of the forty-year-old tree of the
yellow magnum bonum plum, an old variety which has been
propagated by grafts on various stocks for a very long period

282 DEFINITE ACTION OF CONDITIONS OF LIFE. Chap. XXIII.

througliout Europe and North America, and on which a
single bud suddenly produced the red magnum boniim. We
should also bear in mind that distinct varieties, and even
distinct species, — as in the case of j^eaches, nectarines, and
apricots, — of certain roses and camellias, — although separated
by a vast number of generations from any progenitor in
common, and although cultivated under diversified conditions.
have yielded by bud-variatiou closely analogous varieties.
When we reflect on these facts we become deeply impressed
with the conviction that in such cases the nature of the
variation depends but little on the conditions to which the
jolunt has been exposed, and not in any especial manner on
its individual character, but much more on the inherited
nature or constitution of the whole group of allied beings to
which the plant in question belongs. AVe are thus driven to
conclude that in most cases the conditions of life play a
subordinate part in causing any particular modification ; like
that which a spark plays, when a mass of combustibles bursts
into flame — the nature of the flame depending on the com-
bustible matter, and not on the spark. ^^

No doubt each slight variation must have its efficient cause ;
but it is as hopeless an attempt to discover the cause of each,
as to say why a chill or a poison affects one man differently
from another. Even with modifications resulting from the
definite action of the conditions of life, when all or nearly all
the individuals, which have been similarly exposed, are simi-
larly affected, we can rarely see the precise relation between
cause and efiect. In the next chapter it will be shown that
the increased use or disuse of various organs j^i'oduces an
inherited effect. It will further be seen that certain varia-
tions are bound together by correlation as well as by other
laws. Beyond this we cannot at present explain either the
causes or nature of the variability of organic beings.

®^ Professor Weismann argues 'Saison-Dimorphismusder Schmctter-
strongly in favour cf this view in his ling^,' 1875, pp. 40-43.

Chap. XXIV. LAWS OF VAKIATION : NISUS FORM ATI VUS. 283

CHAPTER XXIV.

LAWS OF VARIATION — USP: AND DISUSE, ETC.

ITTSUS FOPvMATlVUS, OR THE CO-ORDINATING POWER OF THE ORGANISATION —
ON THE EFFECTS OP THE INCREASED USE AND DISUSE OF OliGANS —
CHANGED HABITS OF LIFE — ACCLI3IATISATI0N WITH ANIMALS AND PLANTS
— 'VARIOUS METHODS BY WHICH THIS CAN BE EFFECTED — ARRESTS OF
DEVEL0F3IENT — RUDIMENTARY ORGANS.

In this and the two following chapters I shall discuss, as well
as the difficulty of the subject permits, the several laws which
govern Variability. These may be grouped under the effects
of use and disuse, including changed habits and acclimatisation
— arrest of development — correlated variation — the cohesion
of homologous parts — the variability of multiple parts — com-
pensation of growth — the position of buds with respect to the
axis of the plant — and lastly, analogous variation. These
several subjects so graduate into one another that their dis-
tinction is often arbitrar}''.

It may be convenient first briefly to discuss that co-
ordinating and reparative power which is common, in a higher
or lower degree, to all organic beings, and which was formerly
designated by ph3"siologists as nisus formativus.

Bkimenbach and others ^ have insisted that the principle which
permits a Hydra, when cut into fragments, to develop itself into
two or more perfect animals, is the same with that which causes
a wound in the higher animals to heal by a cicatrice. Such cases
as that of the Hydra are evidently analogous to the spontaneous
division or fissiparous generation of the lowest animals, and like-
wise to the budding of j)lants. Between these extreme cases and
that of a mere cicatrice we have every gradation. Spallanzani,- by
cutting off the legs and tail of a Salamander, got in the course of three
months six crops of these members ; so that 687 perfect bones were
reproduced by one animal during one season. At whatever point

* ' An Essay on Generation,* Eng. 209.
translat., p. 18 ; Paget, ' Lectures on ^ ' An Essay on Animal ReproJuc-

Surgical Pathology,' 18")3, vol. i. p. tion,' Eng. translat., 1769, p. 79.

284 LAWS OF VAEIATION. Chap. XX J V.

the limb was cut off, the deficient part, and no more, was exactly
reproduced. When a diseased bone has been removed, a new one
sometimes " gradually assumes the regular form, and all the attach-
" ments of muscles, ligaments, &c., become as complete as before."^

This power of re-growth does not, however, always act perfectly ;
the reproduced tail of a lizard differs in the form of the scales from
the normal tail : \vith certain Ortliopterons insects the large hind
legs are reproduced of smaller size:^ the white cicatrice which in
the higher animals ncites the edges of a deep wound is not formed
of perfect skin, for elastic tissue is not produced till long afterwards.^
" The activity of the nisus formativiis," says Bhimenbach, " is in an
" inverse ratio to the age of the organised body." Its power is also
greater with animals, the lower they stand in the scale of organi-
sation ; and animals low in the scale correspond with the embryos of
higher animals belonging to the same class. Newport's observations ^
afford a good illustration of this fact, for he found that " myriapods,
" whose highest development scarcely carries them beyond the larvae
" of perfect insects, can regenerate limbs and antennae np to the
" time of their last moult ;" and so can the larvae of true insects,
but, except in one order, not in the mature insect. Salamanders cor-
respond in development with the tadpoles or larvae of the tailless
Batrachians, and both possess to a large extent the power of re-
growth ; but not so the mature tailless Batrachians.

Absorption often plays an important j)art in the repair of injuries.
When a bone is broken and does not unite, the ends are absorbed
and rounded, so that a false joint is formed ; or if the ends unite,
but overlap, the projecting parts are removed.^ A dislocated bone
will form for itself a new socket. Displaced tendons and varicose
veins excavate new channels in the bones against which they press.
But absorption comes into action, as Virchow remarks, during the
normal growth of bones ; parts which are solid during youth become
hollowed out for the medullary tissue as the bone increases in size.
In trying to understand the many well-adapted cases of re-growth
when aided by absorption, we should remember that almost all
parts of the organisation, even whilst retaining the same form,
undergo constant renewal ; so that a part which is not renewed would
be liable to absorption.

Some cases, usually classed under the so-called nisus formativus,
at first appear to come under a distinct head ; for not only are old
stxuctures reproduced, but new structures are formed. Thus, after
inflammation "false membranes," furnished with blood-vessels,
lymphatics, and nerves, are developed ; or a foetus escapes from the

^ Carpenter's ' Principles of Comp. Phys.,' p. 479.
Physiology,' 18o4, p. 47 9. ^ Prof. Marey's discussion on the

■* Chariesworth's ' Mag. of Nat. power of co-adaptation in all parts of

Hist.,' vol. i., 1837, p. 145. the organisation is excellent. 'La

^ Paget, 'Lectures on Surgical Machine Animale,' 1873, chap. ix. Sef.

P',thology,' vol. i. p. 239. also Paget, ' Lectures,' &c., p. 257.

6

Quoted by Carpenter, *Comp.

Chap. XXIV. EFFECTS OF USE AND DISUSE. 285

Fallopian tubes, and falls into the abdomen, " nature pours out a
" quantity of plastic lymph, which forms itself into organised mem-
" brane, richly supplied with blood-vessels," and the foetus is
nourished for a time. In certain cases of hydrocephtilus the open
and dangerous spaces in the skull are filled up with new bones,
which interlock by perfect serrated sutures.^ But most physiolo-
gists, especially on the Continent, have now given up the belief in
plastic IjTnph or blastema, and Virchow^ maintains that every
structure, new or old, is formed by the proliferation of pre-existing
cells. On this view -false membranes, like cancerous or other
tumours, are merely abnormal developments of normal growths ;
and we can thus understand how it is that they resemble adjoining
structures ; for instance, that a " false membrane in the serous
" cavities acquires a covering of epithelium exactly like that which
" covers the original serous membrane ; adliesions of the iris may
" become black apparently from the production of pigment-cells like
" those of the uvea." '^

No doubt the power of reparation, though not always perfect, is
an admirable provision, ready for various emergencies, even for such
as occur only at long intervals of time.*^ Yet this power is not more
wonderful than the growth and development of every single creature,
more especially of those which are propagated by iissiparous gene-
ration. This subject has been here noticed, because we may infer
that, when any part or organ is either greatly increased in size or
wholly suppressed through variation and continued selection, the
co-ordinating power of the organisation will continually tend to
bring again all the parts into harmony with one another.

On the Effects of the Increased Use and Disuse of Organs.

It is notorious, and we shall immediately adduce proofs,
that increased use or action strengthens muscles, glands,
sense-organs, &c. ; and that disuse, on the other hand, weakens
them. It has been experimentally proved by Eanke ^^ that
the flow of blood is greatly increased towards any part which
is performing work, and sinks again when the part is at rest.
Consequently, if the work is frequent, the vessels increase in
size and the part is better nourished. Paget ^^ also accounts
for the long, thick, dark-coloured hairs which occasionally

* These cases are given by Blum en- ^^ 'Die BlutA-ertheilung, &c. der

bach in his ' Essay on Generation,' pp. Organe,' 1871, as quoted by Jaeger,

52, 54. ' In Sachen Darwin's,' 1874, p. 48.

^ ' Cellular Pathology,' trans, by See also H. Spencer, ' The Principles

Dr. Chance, 1860, pp. 27, 441. of Biology,' vol. ii. 1866, chap. 3-5.

^* Paget, ' Lectures on Pathology,' ^^ ' Lectures en Pathology,' 1853,

vol. i., 1853, p. 357. vol. i. p. 71.

»' Paget, ibid., p. 150.

286 LAWS OF YAEIATIOX. ':;hap. XXI \^.

grow, even in young cliildren, near old-standing inflamed
surfaces or fractured bones by an increased flow of blood to
the part. When Hunter inserted the spur of a cock into the
comb, which is well supplied with blood-vessels, it grew in
one case spirally to a length of six inches, and in another case
forward, like a horn, so that the bird could not touch the
ground with its beak. According to the interesting observa-
tions of M. Sedillot,^* when a portion of one of the bones of
the leg of an animal is removed, the associated bone enlarges
till it attains a bulk equal to that of the two bones, of which
it has to perform the functions. This is best exhibited in
dogs in which the tibia has been removed ; the companion
bone, which is naturally almost filiform and not one-fifth the
size of the other, soon acquires a size equal to or greater than
that of the tibia. Kow, it is at first difficult to believe that
increased weight acting on a straight bone could, by alternately
increasing and diminishing the pressure, cause the blood to
flow more freely in the vessels which permeate the periosteum
and thus supply more nutriment to the bone. Nevertheless
the observations adduced by Mr. Spencer,^^ on the strengthen-
ing of the bowed bones of rickety children, along their con-
cave sides, leads to the belief that this is possible.

The rocking of the stem of a tree increases in a marked
manner the growth of the woody tissue in the parts which are
strained. Prof. Sachs believes, from reasons which he assigns,
that this is due to the pressure of the bark being relaxed in
such parts, and not as Knight and H. Spencer maintain, to
an increased flow of sap caused by the movement of the
trunk.^^ But hard woody tissue may be developed without
the aid of any movement, as we see with ivy closely attached
to an old wall. In all such cases, it is very difficult to distin-
guish between the effects of long-continued selection and those
which follow from the increased action of the part, or directly
from some other cause. Mr. H. Spencer ^^ acknowledges
this difficulty, and gives as an instance the thorns on trees

»* 'Comptes Rend us,' Sept. 26th, '« Ibid., vol. ii. p. 269. Sachs,

1864, p. 539. 'Text-book of Botany,' 1875, p. 734.

^^ H. Spencer, 'The Principles of ^' Ibid, vol. ii. p. 273.

Biology,' vol. ii. p. 243.

Chap. XXIV. EFFECTS OF USE AND DISUSE. 287

and the shells of nuts. Here we have extremely hard woody
tissue without the possibility of any movement, and without,
as far as we can see, any other directly exciting cause ; and as
the hardness of these parts is of manifest service to the j)lant,
we may look at the result as probably due to the selection of
so-called spontaneous variations. Every one knows that hard
work thickens the epidermis on the hands ; and when we
hear that with infants, long before birth, the epidermis is
thicker on the palms and soles of the feet than on any other
part of the body, as was observed with admiration by Albinus,^^
we are naturally inclined to attribute this to the inherited
effects of long-continued use or pressure. We are tempted to
extend the same view even to the hoofs of quadrupeds ; but
who will pretend to determine how far natural selection may
have aided in the formation of structures of such obvious
importance to the animal ?

That use strengthens the muscles may be seen in the limbs of
artisans who follow different trades; and when a muscle is
strengthened, the tendons, and the crests of bone to which they are
attached, become enlarged ; and this must likewise be the case with
the blood-vessels and nerves. On the other hand, when a limb is
not used, as by Eastern fanatics, or when the nerve supplying it
with nervous power is effectually destroyed, the muscles wither.
So again, when the eye is destroyed the optic nerve becomes
atrophied, sometimes even in the course of a few montlis.^^ The
Proteus is furnished with branchiae as well as with lungs : and
Schreibers^" found that when the animal was compelled to live in
deep water, the branchiae were developed to thrice their ordinary
size, and the lungs were partially atrophied. When, on the other
hand, the animal was compelled to live in shallow water, the lungs
became larger and more vascular, whilst the branchiae disappeared
in a more or less complete degree. Such modifications as these are,
however, of comparatively little value for us, as we do not actually
know that they tend to be inherited.

In many cases there is reason to believe that the lessened use of
various organs has affected the corresponding parts in the offspring.
But there is no good evidence that this ever follows in the course
of a single generation. It appears, as in the case of general or iu-

" Paget, ' Lectures on Pathology,' p. 10) a curious account of the atrophy

vol. ii. p. 209. of the limbs of rabbits after the de«

'® Miiller's ' Phys.,' Eng. translat., struction of the nerve,
pp. 54, 791. Prof. Reed has given ^^ Quoted by Lecoq, in * Geograph,

(' Physiological and Anat. Piesearches,' Bot.,' torn, i,, 1854, p. 182.

288 LAWS OF VARIATION. Chap. XXIV.

definite variability, that several generations must be subjected to
changed habits for any appreciable result. Our domestic fowls,
ducks, and geese have almost lost, not only in the individual but
in the race, their povsrer of flight ; for we do not see a young fowl,
when frightened, take flight like a young pheasant. Hence I was
led carefully to compare the limb-bones of fowls, ducks, pigeons,
and rabbits, with the same bones in the wild parent-species. As
the measurements and weights were fully given in the earlier
chapters I need here only recapitulate the results. With domestic
pigeons, the length of the sternum, the j^rominence of its crest,
the length of the scapulse and furculum, the length of the wings as
measured from tip to tip of the radii, are all reduced relatively to the
same parts in the wild pigeon. The wing and tail feathers, however,
are increased in length, but this may have as little connection with
the use of the wings or tail, as the lengthened hair on a dog with
the amount of exercise wiiich it has habitually taken. The feet of
pigeons, except in the long-beaked races, are reduced in size. "With
fowls the crest of the sternum is less prominent, and is often dis-
torted or monstrous ; the wing-bones have become lighter relatively
to the leg-bones, and are apparently a little shorter in comparison
with those of the parent-form, the OaUus hankiva. With ducks,
the crest of the sternum is affected in the same manner as in the
foregoing cases : the furculum, coracoids, and scapulae are all reduced
in weight relatively to the wiiole skeleton : the bones of the wings
are shorter and lighter, and the bones of the leg^ longer and heavier,
relatively to each other, and relatively to the whole skeleton, in
comparison with the same bones in the wild-duck. The decreased
weight and size of the bones, in the foregoing cases, is probably the
indirect result of the reaction of the weakened muscles on the bones.
I failed to compare the feathers of the wings of the tame and wild
duck ; but Gloger^^ asserts that in the wild duck the tips of the
wing-feathers reach almost to the end of the tail, whilst in the
domestic duck they often hardly reach to its base. He remarks
also on the greater thickness of the legs, and says that the swimming
membrane between the toes is reduced ; but I was not able to
detect this latter difference.

With the domesticated rabbit the body, together with the whole
skeleton, is generally larger and heavier than in the wild animal,
and the leg-bones are heavier in due proi^ortion ; but whatever
standard of comparison be taken, neither the leg-bones nor the
scapulae have increased in length proportionally with the increased
dimensions of the rest of the skeleton. The skull has become in a
marked manner narrower, and, from the measurements of its
capacity formerly given, we may conclude, that this narrowness
results from the decreased size of the brain, consequent on the
mentally inactive life led by these closely-confined animals.

We have seen in the eighth chapter that silk- moths, which have

2» ' Das Abander:. dev Vogel,' 1833, s. 74.

Chap XXIV. EFFECTS OF USE AND DISUSE. 289

been kept during many centuries closely confined, emerge from their
cocoons with their wings distorted, incapable of flight, often greatly
reduced in size, or even, according to Quatrefages, quite rudimentary.
This condition of the wings may be largely owing to the same kind
of monstrosity which often affects wild Lepidoptera when artificially
reared from the cocoon ; or it may be in part due to an inherent
tendency, which is common to the females of many Bombycidse, to
have their wings in a more or less rudimentary state ; but part of
the effect may be attributed to long-continued disuse.

From the foregoing facts there can be no doubt that with
our anciently domesticated animals, certain bones have in-
creased or decreased in size and weight owing to increased or
decreased use ; but they have not been modified, as shown in
the earlier chapters, in shape or structure. AVith animals
living a fiee life and occasionally exposed to severe compe-
tition the reduction would tend to be greater, as it would be
ail advantage to them to have the development of every
superfluous part saved. AVith highly-fed domesticated animals,
on the other hand, there feeems to be no economy^ of growth,
nor any tendency to the elimination of superfluous details.
But to this subject I shall recur.

Turning now to more general observations, Nathusius has
shown that with the improved races of the j)ig, the shortened
legs and snout, the form of the articular condyles of the
occiput, and the position of the jaws with^he upper canine
teeth projecting in a most anomalous manner in front of the
lower canines, may be attributed to these parts not having
been fully exercised. For the highly-cultivated races do not
travel in search of food, nor root up the ground with their
ringed muzzles.'^^ These modifications of structure, which
are all strictly inherited, characterise several improved
breeds, so that they cannot have been derived from any single
domestic stock. With respect to cattle, Professor Tanner has
remarked that the lungs and liver in the imj)roved breeds
" are found to be considerably reduced in size when compared
"with those possessed by animals having perfect liberty ;"2^

22 Nathusius, * Die Racen des Nathusius : ' Der Schadel des Masken*

Schweines,' 1860, s. 53, 57; ' Vor- schweiues,' 1870.
studiea .... Schweineschadel,' 1864, ^s 'Journal of Agriculture of H^gh-

s. 103, 130, 133. Prof. Lucae supports land Soc.,' July, 1860, p. 321.
and estends the conclusions of Von

290 LAWS OF VARIATION. Chap. XXIV.

and tlie reduction of these organs affects the general shape
of the body. The cause of the reduced lungs in highly -bred
animals which take little exercise is obvious; and perhaps
the liver may be aifected b}^ the nutritious and artificial food
on which they largely subsist. Again, Dr. Wilckens asserts ^*
that vaiious parts of the body certainly diifer in AljDine ar.d
h^wland breeds of several domesticated animals, owing to
their different habits of life ; for instance, the neck and fore-
legs in length, and the hoofs in shape.

It is well known that, when an artery is tied, the anastomosing
branches, from being forced to transmit more blood, increase in
diameter ; and this increase cannot be accounted for by mere exten-
sion, as their coats gain in strength. With respect to glands. Sir
J. Paget observes that " when one kidney is destroyed the other
" often becomes much larger, and does double work." ^° If we
compare the size of the udders and their power of secretion in cows
which have been long domesticated, and in certain breeds of the goat
in which the udders nearly touch the ground, with these organs in
wild or half-domesticated animals, the difference is great. A good
cow with us daily yields more than five gallons, or forty pints of
milk, whilst a first-rate animal, kept, for instance, by the Damaras
of South Africa,'''^ "rarely gives more than two or three pints of milk
" daily, and, should her calf be taken from her, she absolutely
" refuses to give any." We may attribute the excellence of our
cows and of certain goats, partly to the continued selection of the
best milking animals, and partly to the inherited efi'ects of the
increased action, through man's art, of the secreting glands.

It is notorious that short-sight is inherited ; and we have seen in
the twelfth chapter from the statistical researches of M. Giraud-
Teulon, that the habit of viewing near objects gives a tendency to
short-sight. Veterinarians are unanimous that horses are affected
with spavins, splints, ringbones, &c., from being shod and from
travelling on hard roads, and they are almost equally unanimous
that a tendency to these malformations is transmitted. Formerly
horses were not shod in North Carolina, and it has been asserted that
they did not then suffer from these diseases of the legs and feet.^^

Our domesticated quadrupeds are all descended, as far as is
known, from species having erect ears ; yet few kinds can be
named, of which at least one race has not drooping ears.

2* " Landwirth. Wochenblatt,' No. in South America, see Aug. St.-Hilaire,

10. ' Voyage dans la Province de Goyaz,'

25 ' Lectures on Surgical Pathology,' torn. i. p. 71.
1853, vol. i. p. 27. " Brickell's 'Nat. Hist, of North

2® Andersson, ' Travels in South Carolina,' 1739, p. 53.
Africa,* p. 318. For analogous cases

Chap. XXIV. EFFECTS OF USE AND DISUSE. 291

Cats in China, horses in parts of Russia, sheep in Italy and else-
where, the guinea-pig formerly in Germany, goats and cattle
in India, rabbits, pigs, and dogs in all long-civilised countries
have dependent ears. With wild animals, which constantly
use their ears like funnels to catch ever}^ passing sound, and
es2:)ecially to ascertain the direction whence it comes, there is
not, as Mr. Blyth has remarked, any species with drooping
ears except the elephant. Hence the incapacity to erect the
ears is certainly in some manner the result of domestication ;
and this incapacity has been attributed by various authors ^^
to disuse, for animals protected b}^ man are not compelled
habitually to use their ears. Col. Hamilton Smith'^^ states
that in ancient effigies of the dog, " with the exception of one
" Egyptian instance, no sculpture of the earlier Grecian era
" produces representations of hounds vnih completely drooping
" ears ; those with them half pendulous are missing in the
" most ancient ; and this character increases, by degrees, in
*' the works of the Roman period." Godron also has remarked
" that the j)igs of the ancient Egyptians had not their ears
" enlarged and pendent. "^^ But it is remarkable that the
drooping of the ear is not accompanied by any decrease in
size ; on the contrary, animals so different as fancy rabbits,
certain Indian breeds of the goat, our petted spaniels, blood-
hounds, and other dogs, have enormously elongated ears, so
that it would appear as if their weight had caused them to
di'oop, aided perhaps by disuse. With rabbits, the drooping
of the much elongated ears has affected even the structure of
the skull.

The tail of no wild animal, as remarked to me by Mr. Blyth,
is curled ; whereas pigs and some races of dogs have their tails
much curled. This deformity, therefore, appears to be the
result of domestication, but whether in any way connected
with the lessened use of the tail is doubtful.

28 Livingstone, quoted by Youatt ' Jahrbuch der deutschen Viehzucht,'

on Sheep, p. 142. Hodgson, in' Jour- 1866.

nal of Asiatic Soc. of Bengal,' vol. xvi., '" ' Naturalist's Library,' Dogs, vol.

1847, p. 1006, &c. &c. On the other ii, 1840, p. 104.
hand, Dr. Wilckens argues strongly ^° ' De I'Espece,' torn, i., 1859, p.

against the belief that the drooping 367.
of the eai-s is the result of disuse :

292 LAWS OF VARIATION. Chap. XXIV.

The epidermis on our liancls is easily tliickened, as every
one knows, by hard work. In a district of Ceylon the sheep
have " horny callosities that defend their knees, and which
" arise from their habit of kneeling down to crop the short
" herbage, and this distinguishes the Jaffna flocks from those
" of other portions of the island ;" but it is not stated whether
this peculiarity is inherited. ^^

The mucous membrane which lines the stomach is con-
tinuous with the external skin of the bod}'" ; therefore it is
not surprising that its texture should be affected by the
nature of the food consumed, but other and more interesting
changes likewise follow. Hunter long ago observed that the
muscular coat of the stomach of a gull (Lams tridadylus)
which had been fed for a year chiefly on grain was thickened ;
and, according to Dr. Edmondston, a similar change periodi-
cally occurs in the Shetland Islands in the stomach of the
Lariis argentatus, which in the spring frequents the corn-
fields and feeds on the seed. 1'he same careful observer has
noticed a great change in the stomach of a raven which had
been long fed on vegetable food. In the case of an owl (^Strix
grallaria), similarly treated, Menetries states that the form of
the stomach was changed, the inner coat became leathery,
and the liver increased in size. Whether these modifications
in the digestive organs would in the course of generations
become inherited is not known. ^^

The increased or diminished length of the intestines, which
apparently results from changed diet, is a more remarkable
case, because it is characteristic of certain animals in their
domesticated condition, and therefore must be inherited.
The complex absorbent system, the blood-vessels, nerves, and
muscles, are necessarily all modified together with the
intestines. According to Daubenton, the intestines of the
domestic cat are one-third longer than those of the wild cat
of Europe ; and although this species is not the parent-stock
of the domestic animal, yet, as Isidore Geoffrey has remarked,

2' 'Ceylon,' by Sir J. E. Tennent, as quoted in Macgillivray's 'British

1859, vol. ii. p. 531. Birds,' vol. v. p. 550: Menetries, as

22 For the foregoing statements, see quoted in Bronn's ' Geschichte der

Hunter's 'Essays and Observations,' Natur,' B. ii. s. 110.
1861, vol. ii. p. 329; Dr. Edmondston,

Chap. XXIV. CHANGED HABITS OF LIFE. 293

the several species of cats are so closely allied that the
comparison is probably a fair one. The iu creased length
appears to be due to the domestic cat being less strictly car-
nivorous in its diet than any wild feline species ; for instance,
I have seen a French kitten eating vegetables as readily as
meat. According to Cuvier, the intestines of the domesticated
pig exceed greatly in proportionate length those of the wild
boar. In the tame and wild rabbit the change is of an
opposite nature, and probably results from the nutritious food
given to the tame rabbit.^^

Changed and inherited Habits of Life. — This subject, as far as
the mental powers of animals are concerned, so blends into
instinct, that I will here only remind the reader of such cases
as the tameness of our domesticated animals — the poin'ing or
retrieving of dogs — their not attacking the smaller animals
kept by man — and so forth. How much of these changes
ought to be attributed to mere habit, and how much to the
selection of individuals which have varied in the desired
manner, irrespectively of the special circumstances under
which they have been kept, can seldom be told.

We have already seen that animals may be habituated to
a changed diet ; but some additional instances may be given.
In the Polynesian Islands and in China the dog is fed exclu-
sively on vegetable matter, and the taste for this kind of food
is to a certain extent inherited.^"^ Our sporting dogs will not
touch the bones of game birds, whilst most other dogs devour
them with greediness. In some parts of the world sheep have
been largely fed on fish. The domestic hog is fond of barley,
the wild boar is said to disdain it; and the disdain is partially
inherited, for some j^'oung wild pigs bred in captivity showed
an aversion for this grain, whilst others of the same brood
relished it."^ One of my relations bred some young pigs
from a Chinese sow by a wild Alpine boar ; they lived free
in the park, and were so tame that they came to the house to

** These statoments on the intestines borne,' 1825, vol. ii. p. 121.

!' re taken from Isidore Geoffroy Saint- ^* Burdach, 'Traite de Phys.,' torn.

Hilaire, 'Hist. iSat. Gen.,' torn. iii. pp. ii. p. 267, as quoted by Dr. P. Lucas^

427, 44 1. ' L'Hered. Nat.,' torn. i. p. 388.

s* Gilbert White ' Xat. Hist. Sel-

294 LAWS OF VAEI VI ION. Chap. XX1\

"be fed ; but tliey would not touch swiil, which was devoured
by the other pigs. An animal when once accustomed to an
unnatural diet, which can generally be effected only during
youth, dislikes its proper food, as Spallanzani found to be
the case with a pigeon which had been long fed on meat.
Individuals of the same species take to new food with different
degrees of readiness ; one horse, it is stated, soon learned to
eat meat, whilst another would have perished from hunger
rather than have partaken of it.^^ The caterpillars of the
Bomhyx Jiesperus feed in a state of nature on the leaves of the
Cafe diable, but, after having been reared on the Ailanthus,
they would not touch the Cafe diable, and actually died of
hunger.^^

It has been found possible to accustom marine fish to live
in fresh water ; but as such changes in fish and other marine
animals have been chiefly observed in a state of nature, they
do not properly belong to our present subject. The period
of gestation and of maturity, as shown in the earlier chapters,
— the season and the frequency of the act of breeding, — have
all been greatly modified under domestication. With the
Eg3"ptian goose the rate of change with respect to the season
has been recorded,^^ The wild drake pairs with one female,
the domestic drake is polygamous. Certain breeds of fowls
have lost the habit of incubation. The paces of the horse,
and the manner of flight of certain breeds of the pigeon,
have been modified and are inherited. Cattle, horses, and
pigs have learnt to browse under water in the St. John's River,
East Florida, where the Vallisneria has been largely natural-
ised. The cows were observed by Prof. Wyman to keep their
heads immersed for " a period varying from fifteen to thirt}--
five seconds."^^ The voice differs much in certain kinds of
fowls and pigeons. Some varieties are clamorous and others
silent, as the Call and common duck, or the Spitz and pointer
dog. Every one knows how the breeds of the dog differ from

^^ This and several other cases are 563.
given by Colin, ' Physiologic Comp. ^8 Quatrefages, * Unite de I'Espece

des Animaux Dom.,' 1854, torn. i. p. Humaine,' 1861, p. 79.
426. ^® ' The American Naturalist,' Ap^ '

" M. Michely de Cayenne, in ' Bull. 1874, p. 237.
Soc. d'Acclimat.,' torn, viii., 1861, p.

Chap. XXIV. ACCLIMATISATION. 295

one another in their manner of hunting, and in their ardour
after different kinds of game or vermin.

With plants the period of vegetation is easily changed and
is inherited, as in the case of summer and winter wheat,
barley, and vetches ; but to this subject we shall immediatel}^
return under acclimatisation. Annual plants sometimes
become perennial under a new climate, as I hear from Dr.
Hooker is the case with the stock and mignonette in Tasmania.
On the other hand, perennials sometimes become annuals, as
with the Ricinus in England, and as, according to Captain
Mangles, with many varieties of the heartsease. Von Berg ^°
raised from seed of Verhascum phoeniceum, which is usually a
biennial, both annual and perennial varieties. Some de-
ciduous bushes become evergreen in hot countries.^^ Eice
requires much water, but there is one variety in India which
can be grown without irrigation.*'^ Certain varieties of the
oat and of our other cereals are best fitted for certain soils. '^^
Endless similar facts could be given in the animal and vege-
table kingdoms. They are noticed here because they illustrate
analogous differences in closely allied natural species, and
because such changed habits of life, whether due to habit, or
to the direct action of external conditions, or to so-called spon-
taneous variability, would be apt to lead to modifications of
structure.

Acclimatisation. — From the previous remarks we are
naturally led to the much disputed subject of acclimatisation.
There are two distinct questions : Do A^arieties descended from
the same species differ in their power of living under different
climates ? And secondly, if they so differ, how have they
become thus adapted ? We have seen that Euroj)ean dogs do
not succeed well in India, and it is asserted,*'* that no one has
there succeeded in keeping the Newfoundland long alive ; but
then it may be argued, and probably Avith truth, that these

•«o ' Flora,' 1835, B. ii. p. n04. *^ ' Gardeuer's Chronicle,' I80O,

<» Alph. de CaadoUe, ' Geograph. pp. 204, 219.

Bot.,' torn. ii. p. 1078. ** Rev. R. Everest, ' Journal As.

*'^ Royle, 'Illustrations of the Soc. of Bengal,' vol. iii. p. 19.
Botany of the Himalaya,' p. 19.

29G LAWS OF VAEIATION. Chap. XXIV.

northern breeds are specifically distinct from the native dogs
which flourish in India. The same remark may be made with
respect to different breeds of sheep, of which, according to
Yoiiatt,^^ not one broiight " from a torrid climate lasts out
*' the second year," in the Zoological Gardens. But sheep
are capable of some degree of acclimatisation, for Merino sheep
bred at the Cape of Good Hope have been found far better
adapted for India than those imported from England.**^ It is
ahnost certain that all the breeds of the fowl are descended
from one species ; but the Spanish breed, which there is good
reason to believe originated near the Mediterranean,*'^ though
so fine and vigorous in England, suffers more from frost than
any other breed. The Arrindy silk moth introduced from
Bengal, and the Allan thus moth from the temperate province
of Shan Tung, in China, belong to the same species, as we
may infer from their identity in the caterpillar, cocoon, and
mature states ; *^ jet they differ much in constitution : the
Indian form " will flourish only in warm latitudes," the other
is quite hardy and withstands cold and rain.

Plants are more strictly adapted to climate than are animals. The
latter when domesticated withstand such great diversities of climate,
that we find nearly the same species in tropical and temperate
countries ; whilst the cultivated plants are widely dissimilar. Hence
a larger field is open for inquiry in regard to the acclimatisation of
plants than of animals. It is no exaggeration to say that with almost
every plant which has long been cultivated, varieties exist which
are endowed with constitutions fitted for very different climates ; I
will select only a few of the more striking cases, as it would be
tedious to give all. In North America numerous fruit-trees have
been raised, and in horticultural publications, — for instance, in that
by Downing, — lists are given of the varieties which are best able to
withstand the severe climate of the northern States and Canada.
Many American varieties of the pear, plum, and peach are excellent
in their own country, but until recently, hardly one w^as known that
succeeded in England ; and with apples,^^ not one succeeds. Though
the American varieties can withstand a severer winter than ours, the

*^ Youatt on Sheep, 1838, p. 491. municated to Bot. Soc. of Canada,

*^ Roy le, ' Prod. Resources of India,' quoted in the 'Reader,' 1863, iS'ov

p. 153. 13th.

•*' Tegetnieier, ' Poultry Book,' '*^ See remarks by Editor in ' (lard.

1886, p. 102. " Chronicle,' 1848, p. 5.

•** Dr. R. Paterson, in a paper com-

Chap. XXIV. ACCLIMATISATION. 297

summer here is not hot enonp;h. Fruit-trees have also originated
in Europe with different constitutions, but they are not much
noticed, because nurserymen here do not supply wide areas. The
Forelle pear flowers early, and when the flowers have just set, and
this is the critical period, they have been observed, both in France
and England, to withstand with complete impunity a frost of 18°
and even 14° Fahr., which killed the flowers, whether fully expanded
or in bud, of all other kinds of pears.^*^ This power in the flower of
resisting cold and afterwards producing fruit does not invariably
depend, as we know on good authority ,^^ on general constitutional
vigour. In proceeding northward, the number of varieties which
are found capable of resisting the climate rapidly decreases, as may
be seen in the list of the varieties of the cherry, apple, and pear,
which can be cultivated in the neighbourhood of Stockholm. ^^ Near
Moscow, Prince Troubetzkoy planted for experiment in tVe open
ground several varieties of the pear, but one alone, the Poire san <
Fepins, withstood the cold of winter.^^ We thus see that our fruit-
trees, like distinct species of the same genus, certainly differ frjm
each other in their constitutional adaptation to different climates.

With the varieties of many plants, the adaptation to climate is
often very close. Thus it has been proved by repeated trials " that
" few if any of the English varieties of wheat are adapted for culti-
" vation in Scotland ; " ^* but the failure in this case is at first only
in the quantity, though ultimately in the quality, of the grain
produced. The Eev. M. J. Berkeley sowed wheat-seed from India,
and got " the most meagre ears,"' on land which would certainly
have yielded a good crop from English wiieat,^^ In these cases
varieties have been carried from a warmer to a cooler climate ; in
the reverse case, as " when wheat was imported directly from France
" into the West Indian Islands, it produced either Avholly barren
" spikes or furnished with only two or three miserable seeds, while
" West Indian seed by its side yielded an enormous harvest." ^'^
Here is another case of close adaptation to a slightly cooler climate ;
a kind of wheat which in England may be used indiflerently either
as a winter or summer variety, when sown under the warmer
climate of Grignan, in France, behaved exactly as if it had been a
true winter wheat.^^

Botanists believe that all the varieties of maize belong to the
same species ; and we have seen that in North America, in proceed-
ing northward, the varieties cultivated in each zone produce their

50 ' Gard. Chronicle,' 1860, p. 938. p. 7.
Remarks by Editor and quotation ^^ 'Gard. Chronicle,' 1851, p. 39(5.

from Decaisne. ^^ Ibid., 1862, p. 235.

5' J. de Jonghe, of Brussels, in ^^ On the authority of Labat,

'Gard. Chronicle,' 1857, p. 612. quoted in 'Gard. Chron.,' 1862, p.

" Ch. Martins, ' Voyage Bot. Cotes 235.
Sept. de la Norvege,' p. 26. ^^ MM. Edwards and Colin, ' Annal.

5^ ' Journal de I'Acad. Hort. de des Sc. Nat.,' 2nd series, Bot., torn. v.

Gand,' quoted in ' Gard. Chron.,' 1859, p. 22.

298 LAWS OF VARIATION. Chap. XXIV.

flowers and ripen their seed within shorter and shorter periods. So
that the tall, slowly maturing southern varieties do not succeed in
New England, and the New English varieties do not succeed in
Canada. I have not met Avith any statement that the southern
varieties are actually injured or killed by a degree of cold which the
northern varieties can withstand with impunity, though this is
probable ; but the production of earJy flowering and early seeding
varieties deserves to be considered as one form of acclimatisation.
Uence it has been found possible, according to Kalm, to cultivate
maize further and further northwards in America. In Europe, also,
as we learn from the evidence given by Alph. de Candolle, the
culture of maize has extended since the end of the last century
thirty leagues north of its former boundary.^^ On the authority of
Linnfeus,^^ I may quote an analogous case, namely, that in Sweden
tobacco raised from home-grown seed ripens its seed a month
soimer and is less liable to miscarry than j^lants raised from foreign
Beed.

With the Vine, differently from the maize, the line of practical
culture has retreated a little southward since the middle ages;*^*^ but
this seems due to commerce being now easier, so that it is better to
import wine from the south than to make it in northern districts.
Nevertheless the fact of the vine not having spread northward shows
that acclimatisation has made no progress during several centuries.
There is, however, a marked ditference in the constitution of the
several varieties, — some being hardy, whilst others, like the muscat
of Alexandria, require a\eryhigh temperature to come to perfection.
According to Labat,*^^ vines taken from France to the West Indies
succeed with extreme difiiculty, whilst those imported from Madeira
or the Canary Islands thrive admirably.

Gallesio gives a curious account of the naturalisation of the Orange
in Italy. During many centuries the sweet orange was propagated
exclusively by grafts, and so often suffered from frosts, that it re-
quired protection. After the severe frost of 1709, and more especially
after that of 1763, so many trees were destroyed, that seedlings from
the sweet orange were raised, and, to the surprise of the inhabitants,
their fruit was found to be sweet. The trees thus raised were larger,
more productive, and hardier than the old kinds; and seedlings are
now continually raised. Hence Gallesio concludes that much more
was effected for the naturalisation of the orange in Italy by the
accidental production of new kinds during a period of about sixty
years, than had been effected by grafting old varieties during many
ages.^'^ I may add that Risso ^^ describes some Portuguese varieties

58 < Geograph. Bot.,' p. 337. p. 339.

59 'Swedish Acts,' Eng. translat., «i ' Gard. Chronicle,' 1862, p. 235.
1739-40, vol. i. Kalm, in his 'Travels,' ^^ Gallesio, ' Teoria della Ripro-
vol. ii. p. 166, gives an analogous duzione Veg.,' 1816, p. 125 ; and
case with cotton-plants raised in New 'Traite du Citrus,' 1811, p. 359.
jersey from Carolina seed. ®' ' Essai sur I'Hist. des Grangers,*

«« De Candolie, 'Geograph. Bot.,' 1813, p. 20, &c.

Chap. XXIV. ACCLIMATISATION. 299

of the orange as extremely sensitive to cold, and as mucli tcnderei
than certain other varieties.

The peach was known to Theophrastns, 322 b.c.^* According to
the autliorities quoted by Dr. F. Eolle,*^^ it was tender when first
introduced into Greece, and even in the island of Ehodes only
occasionally bore fruit. If this be correct, the peach, in spreading
during the last two thousand years over the middle parts of Europe,
must have become much hardier. At the present day different
varieties differ much in hardiness : some French varieties will not
succeed in England; and near Paris, the Pavie de Bonneuil does not
ripen its fruit till very late in the season, even when grown on a
wall ; " it is, therefore, only fit for a very hot southern climate." "^

I will briefly give a few other cases. A variety of Alagnolia
grandiflora, raised by M. Eoy, withstands a temperature several
degrees lower than that which any other variety can resist. With
camellias there is much difference in hardiness. One particular
variety of the Noisette rose withstood the severe frost of 18G0 " un-
*' touched and hale amidst a universal destruction of other Noisettes."
In New York the " Irish yew is quite hardy, but the common yew
*' is liable to be cut down." I may add that there are varieties of
the sweet potato (Convolmdus batatas) which are suited for warmer,
as well as for colder, climates.'''^

The plants as jet mentioned have been found capable of
resisting an unusual degree of cold or heat, when fully grown.
The following cases refer to plants whilst j^oung. In a large
bed of young Araucarias of the same age, growing close to-
gether and equally exposed, it was observed,^*^ after the
unusually severe winter of 1860-61, that, "in the midst of
" the dying, numerous individuals remained on which the
" frost had absolutely made no kind of impression." Dr.
Lindley, after alluding to this and other similar cases,
remarks, " Among the lessons which the late formidable
" winter has taught us, is that, even in their power of
" resisting cold, individuals of the same species of plants are
" remarkably different." Near Salisbury, there was a sharp
frost on the night of May 24th, 1836, and all the French

64

Alph. de Candolle, ' Geograph. For camellias and I'oses, see * Gard.

Bot.,' p. 88-2. Chrou.,' ISOO, p. 384-. For the yew,

^' 'Ch. Darwin's Lehre von der ' Journal of Hort.,' March 3rd, 1863,

Entstehimg,' &c., 1862, s, 87. p 174. For sweet potatoes, see Co].

®^ Decaisne, quoted in ' Gard. Chro- von Siebold, in 'Gard. Chron.,' 1855,

nicle,' 1865, p. 271. p. 822.

" For the magnolia, see Loudon's «* The Editor, 'Gard. Chron.,' 1861,

'Gard. Mag.,' vol. xiii., 1837, p. 21. p. 239.

300 LAWS OF VARIATION. Chap. XXIV.

"beans (Pliaseolus vulgaris) in a bed were killed except about
one in thirty, which completely escaped. ^^ On the same day of
the month, but in the year 1864, there was a severe frost in
Kent, and two rows of scarlet-runners (P. multifiorus) in my
garden, containing 390 plants of the same age and equally
exposed, were all blackened and killed except about a dozen
plants. In an adjoining row of " Fulmer's dAvarf bean"
(P. vulgaris)^ one single plant escaped. A still more severe
frost occurred four days afterwards, and of the dozen j)lants
which had previously escaped only three survived ; these
were not taller or more vigorous than the other young plants,
but they escaped completely, with not even the tips of their
leaves browned. It was impossible to behold these three
plants, with their blackened, withered, and dead brethren all
around, and not see at a glance that they differed widely in
constitutional power of resisting frost.

This work is not the proper place to show that wild plants
of the same species, naturally growing at different altitudes
or under different latitudes, become to a certain extent accli-
matised, as is proved by the different behaviour of their seed-
lings when raised in another country. In my ' Origin of
Species ' I have alluded to some cases, and I could add many
others. One instance must suffice : Mr. G rigor, of Forres,'^*^
states that seedlings of the Scotch fir (Pinns sylvestris), raised
from seed from the Continent and from the forests of Scotland,
differ much. " The difference is perceptible in one-year-old,
" and more so in two-year-old seedlings ; but the effects of
" the winter on the second year's growth almost uniformly
" make those from the Continent quite brown, and so damaged,
" that by the month of March they are quite unsaleable,
" while the plants from the native Scotch pine, under the
" same treatment, and standing alongside, although consider-
" ably shorter, are rather stouter and quite green, so that the

«» Loudon's * Gard. Mag.,' vol. xii., plants, which he cultivated in

1836, p. 378. England alongside specimens from

■<"Gardeuer'sChron.,*1865, p. 699. northern districts; and he found a

Mr. G. Maw gives ('Gard. Chron.' great difference not only in their

1870, p. 895) a number of striking hardiness during the winter, but in

cases ; he brought home from south- the behaviour of some of them

ern Spain and northern Africa several during the summer.

Chap. XXIV. ACCLIMATISATION. 301

" beds of the one can "be known from the other when seen
" from the distance of a mile." Closely similar facts have been
observed with seedling larches.

Hardy varieties would alone be valued or noticed in Europe ;
whilst tender varieties, requiring more warmth, would generally be
neglected; but such occasionally arise. Thus Loudon ^^ describes a
Cornish variety of the elm which is almost an evergreen, and of
which the shoots are often killed by the autumnal frosts, so that its
timber is of little value. Horticulturists know that some varieties
are much more tender than others : thus all the varieties of the
broccoli are more tender than cabbages ; but there is much difference
in this respect in the sub- varieties of the broccoli ; the pink and
fjurple kinds are a little hardier than the white CajDC broccoli, " but
" they are not to be depended on after the thermometer falls below
" 2i° Fahr. ;" the Walcheren broccoli is less tender than the Cape,
and there are several varieties which will stand much severer cold
than the AValcheren.'^^ Cauliflowers seed more freely in India than
cabbages.^^ To give one instance with flowers : eleven j)lants raised
from a hollyhock, called the Queen of the Wliites,"'^ were found to be
much more tender than various other seedlings. It may be pre-
sumed that all tender varieties would succeed better under a climate
warmer than ours. "With fruit-trees, it is well known that certain
varieties, for instance of the peach, stand forcing in a hot-house
better than others ; and this shows either pliability of organisation
or some constitutional difference. The same individual cherry-tree,
when forced, has been observed during successive years gradually to
change its period of vegetation.'*^ Few pelargoniums can resist the
heat of a stove, but Alha Multiflora will, as a most skilful gardener
asserts, " stand pine-apple top and bottom heat the whole winter,
*' without looking any more drawn than if it had stood in a common
'' greenhouse ; and Blanche Fleur seems as if it had been made on
" purpose for growing in winter, like many bulbs, and to rest all
'' summer." ^*^ There can hardly be a doubt that the Alba Multiflora
pelargonium must have a widely different constitution from that of
most other varieties of this plant ; it would probably withstand even
an equatorial climate.

We have seen that according to Labat the vine and wheat require
acclimatisation in order to succeed in the West Indies, Similar
facts have been observed at Madras : "two parcels of mignonette-

^' 'Arboretum ol I'ruticetuni,' vol. ^^ 'Gardener's Chronicle,* 1841, p.

lij. p. 1376. 291.

" T.Ir. Robson, in ' Journal of "•* Mr. Beaton, in ' Cottage Gar-
Horticulture,' lS*n, p. 23. deuer,' March 20th, 18'30, p. 377.

^' Dr. Bonavia, ' Report of the Queen Mab will also stand stove heat.

Agri.-Hort. Soc. of Oudh,' 1866. See ' Gardener's Chronicle,* 1845, p.

1* ' Cottage Gardener,' 1860, April 226.
24th, p. 57.

35

302 LAWS OF VAKIATION. Chap. XXIY

" seed, one direct from Europe, the other saved at Bangalore (of
" which the mean temperature is much below that of Madras), were
*' sown at the same time : they both vegetated equally favourably,
" but the former all died off a few days after they appeared above
" ground; the latter still survive, and are vigorous, healthy plants."
" So again, turnip and carrot seed saved at Hyderabad are found to
*' answer better at Madras than seed from Europe or from the Cape
'' of Good Hope." " Mr. J. Scott of the Calcutta Botanic Gardens,
informs me that seeds of the sweet-pea (Lathy rus odoratus) imported
from England produce plants, with thick, rigid stems and small
leaves, which rarely blossom and never yield seed ; plants raised from
French seed blossom sparingly, but all the flowers are sterile ; on
the other hand, plants raised from sweet-peas grown near Darjeeling
in Upper India, but originally derived from England, can be suc-
cessfully cultivated on the plains of India ; for they flower and seed
profusely, and their stems are lax and scandent. In some of the
foregoing cases, as Dr. Hooker has remarked to me, the greater
success may perhaps be attributed to the seeds having been more
fully ripened under a more favourable climate ; but this view can
hardly be extended to so many cases, including plants, which, from
being cultivated under a climate hotter than their native one,
become fitted for a still hotter climate. We may therefore safely
conclude that plants can to a certain extent become accustomed to
a climate either hotter or colder than their own ; although the latter
cases have been more frequently observed.

We will now consider the means by which acclimatisation
may be effected, namely, through the appearance of varieties
having a different constitution, and through the effects of
habit. In regard to new varieties, there is no evidence that
a change in the constitution of the offspring necessarily stands
in any direct relation with the nature of the climate inhabited
by the parents. On the contrary, it is certain that hardy
and tender varieties of the same species appear in the same
country. New varieties thus spontaneously arising become
fitted to slightly different climates in two different ways ;
firstly, they may have the power, either as seedlings or when
full-grown, of resisting intense cold, as with the Moscow
pear, or of resisting intense heat, as with some kinds of
Pelargonium, or the flowers may withstand severe frost, as
with the Forelle pear. Secondly, plants may become adapted
to climates widely different from their own, from flowering
and fruiting either earlier or later in the season. In both

^' 'Gardener's Chronicle,' 1841, p. 439.

Chap. XXIV. ACCLIMATISATION. 303

these cases the power of acclimatisation by man consists
simply in the selection and preservation of new varieties.
But without any direct intention on his part of securing
a hardier variety, acclimatisation may be unconsciously
eifected by merely raising tender plants from seed, and by
occasionally attempting their cultivation further and further
northwards, as in the case of maize, the orange and the
peach.

How much influence ought to be attributed to inherited
habit or custom in the acclimatisation of animals and plants
is a much more difficult question. In many cases natural
selection can hardly have failed to have come into play and
complicated the result. It is notorious that mountain sheep
resist severe weather and storms of snow which would destroy
lowland breeds ; but then mountain sheep have been thus
exposed from time immemorial, and all delicate individuals
will have been destroyed, and the hardiest preserved. So
with the Arrindy silk-moths of China and India ; who can
tell how far natural selection may have taken a share in the
formation of the two races, which are now fitted for such
widely different climates ? It seems at first probable that the
many fruit-trees which are so well fitted for the hot summers
and cold winters of North America, in contrast with their
poor success under our climate, have become adapted through
habit ; but when we reflect on the multitude of seedlings
annually raised in that countr}^, and that none would succeed
unless born with a fitting constitution, it is possible that
mere habit may have done nothing towards their acclima-
tisation. On the other hand, when we hear that Merino
sheep, bred during no great number of generations at the
Cape of Good Hope — that some European plants raised
during only a few generations in the cooler parts of India,
withstand the hotter parts of that country much better than
the sheep or seeds imported directly from England, we must
attribute some influence to habit. We are led to the same
conclusion when we hear from Kaudin ''^ that the races of
melons, squashes, and gourds, which have long been cultivated

'^ Quoted by Asa Gray, in 'Am. Journ. of Sci.,' 2nd series, Jan. 1865,
l'. 106.

304: LAWS OF VARIATION. Chap. XXIV.

in Northern Europe, are comparatively more precocious, and
need much less heat for maturing their fruit, than the
varieties of the same species recently brought from tropical
regions. In the reciprocal conversion of summer and winter
wheat, barley, and vetches into each other, habit produces
a marked effect in the course of a very few generations.
The same thing apparently occurs with the varieties of
maize, which, when carried from the Southern States of
America, or into Germany, soon became accustomed to their
new homes. With vine-plants taken to the West Indies from
Madeira, which are said to succeed better than plants brought
directlj'- from France, we have some degree of acclimatisation
in the individual, independently of the production of new
varieties by seed.

The common experience of agriculturists is of some value,
and they often advise persons to be cautious in trying the
productions of one country in another. The ancient agri-
cultural writers of China recommend the preservation and
cultivation of the varieties peculiar to each country. During
the classical period. Columella wrote, " Vernaculum pecus
" peregrine longe preestantius est.""^

I am aware that the attempt to acclimatise either animals
or plants has been called a vain chimera. No doubt the
attempt in most cases deserves to be thus called, if made in-
dependently of the production of new varieties endowed with
a different constitution. With plants propagated by buds,
habit rarely produces any effect ; it apparently acts only
through successive seminal generations. The laurel, haj^
laurestinus, &c., and the Jerusalem artichoke, which are pro-
pagated by cuttings or tubers, are probably now as tender in
England as when first introduced ; and this appears to be the
case with the potato, which until recently was seldom mul-
tiplied by seed. With plants propagated by seed, and with
animals, there will be little or no acclimatisation unless the
hardier individuals are either intentionally or unconsciously
preserved. The kidney-bean has often been advanced as an

^® For China, see ' Memoire sur ' Journal de Physique,' torn, xxiv.,
les Chiuois,' torn, xi., 1786, p. 60. 178J-,
Columella is quoted hj Carljer, in

Chap. XXIV. ACCLIMATISATION. 305

instance of a plant wliicli lias not become hardier since its
first introduction into Britain. We hear, however, on excel-
lent authority,^*^ that some verj^fine seed, imported from abroad,
produced plants " which blossomed most profusely, but were
" nearly all but abortive, whilst plants grown alongside from
"English seed podded abundantly;" and this apparently
shows some degree of acclimatisation in our English plants.
We have also seen that seedlings of the kidney-bean occasion-
ally appear with a marked jDower of resisting frost ; but no
one, as far as I can hear, has ever separated such hardy
seedlings, so as to j)revent accidental crossing, and then
gathered their seed, and repeated the process year after year.
It may, however, be objected with truth that natural selection
ought to have had a decided effect on the hardiness of our
kidney-beans ; for the tenderest individuals must have been
killed during every severe spring, and the hardier preserved.
But it should be borne in mind that the result of increased
hardiness would simply be that gardeners, who are alwaj's
anxious for as early a crop as possible, would sow their seed
a few days earlier than formerly. iS'ow, as the period of sowing
depends much on the soil and elevation of each district, and
varies with the season ; and as new varieties have often been
imported from abroad, can we feel sure that our kidney-beans
are not somewhat hardier ? I have not been able, by searching
old horticultural works, to answer this question satisfactorily.
On the whole the facts now given show that, though habit
does something towards acclimatisation, yet that the ap-
pearance of constitutionally different individuals is a far more
effective agent. As no single instance has been recorded
either with animals or plants of hardier individuals having
been long and steadily selected, though such selection is
admitted to be indispensable for the improvement of any other
character, it is not surjDrising that man has done little in the
acclimatisation of domesticated animals and cultivated plants.
We need not, however, doubt that under nature new races
and new species would become adapted to widely different
climates, by variation, aided by habit, and regulated by
natural selection.

*" Messrs. Hardy and Sun, in ' Gard. Chronicle,' 185G, p. .189.

806 LAWS OB' VXkiATION. Chap. XXIV.

Arrests of Develoj/ment : Mudimentary and Aborted Organs.

Modifications of structure from arrested development, so great
or so serious as to deserve to be called monstrosities, are not in-
frequent with domesticated animals, but, as they ditfer much from
any normal structure, they require only a passing notice. Thus
the whole head may be represented by a soft nipple-like projec-
tion, and the limbs by mere papillae. These rudiments of limbs are
sometimes inherited, as has been observed in a dog.'^^

Many lesser anomalies appear to be due to arrested development.
What the cause of the arrest may be, we seldom know, except in
the case of direct injury to the embryo. That the cause does not
generally act at an extremely early embryonic period we may infer
from the affected organ seldom being wholly aborted, — a rudiment
being generally jDreserved. The external ears are represented by
mere vestiges in a Chinese breed of sheep ; and in another breed,
the tail is reduced " to a little button, suffocated in a manner, by
fat." ^'^ In tailless dogs and cats a stump is left. In certain breeds of
fowls the comb and wattles are reduced to rudiments ; in the Cochin-
China breed scarcely more than rudiments of spurs exist. With
polled Suffolk cattle, " rudiments of horns can often be felt at an
" early age ;" ^^ and with species in a state of nature, the relatively
great development of rudimentary organs at an early period of
life is highly characteristic of such organs. With hornless breeds
of cattle and sheep, another and singular kind of rudiment has
been observed, namely, minute dangling horns attached to the skin
alone, and which are often shed and grow again. With hornless
goats, according to Desraarest,**^ the bony protuberance which
properly supports the horn exists as a mere rudiment.

With cultivated plants it is far from rare to find the petals,
stamens, and pistils represented by rudiments, like those observed
in natural species. So it is with the whole seed in many fruits ;
thus, near Astrakhan there is a gi*ape with mere traces of seeds, " so
" small and lying so near the stalk that they are not perceived in
" eating the grape." ^^ In certain varieties of the gourd, the tendrils,
according to Naudin, are represented by rudiments or by various
monstrous growths. In the broccoli and cauliflower the greater
number of the flowers are incapable of expansion, and include
rudimentary organs. In the Feather hyacinth {Mtiscavi comostim)
in its natural state the upper and central flowers are brightly
coloured but rudimentary ; under cultivation the tendency to

81 Isid.GeoffroySaint-Hilaire,'Hist. ^4 ^ E^c^^ciop^ Method.,' 1820, p.

Nat. des Anomalies,' 1836, torn. ii. 433 : see p. 500, on the Indian zebu

pp.210, 223, 224, 395; ' Philosoph. casting its horns. Similar cases in

Transact.,' 1775, p. 313. European cattle were given in the

*2 Pallas, quoted ^y Youatt on third chapter.

Sheep, p. 25. *^ Pallas, ' Travels,' Eng. Translat.,

"3 Youatt on Cattle, 1834, p. 174. vol. i. p. 243.

Chap. XXIV. AKRESTED DEVELOPMENT AND KUDIMENTS. 307

abortion travels downwards and outwards, and all the flowers
become rndimentary ; but the abortive stamens and pistils are not
so small in tlie lower as in the upper flowers. In the Viburnum
onulus, on the other hand, the outer flowers naturally have their
oi-gans of fructification in a rudimentary state, and the corolla is of
large size; under cultivation, tlie change spreads to the centre, and
all the flowers become affected. In the compositse, the so-called
doubling of the flowers consists in the greater development of the
corolla of the central florets, generally accompanied with some degree
of sterility ; and it has been observed ^'^ that the progressive doubling
invariably spreads from the circumference to the centre, — that is,
from the ray florets, which so often include rudimentary organs, to
those of the disc. I may add, as bearing on this subject, that with
Asters, seeds taken from the florets of the circumference have been
found to yield the greatest number of double flowers.^^ In the
above cases we have a natural tendency in certain parts to be rudi-
mentary, and this under culture spreads either to, or from, the axis
of the plant- It deserves notice, as showing how the same laws
govern the changes which natural species and artificial varieties
undergo, that in the species of Carthamus, one of the Compositse, a
tendency to the abortion of the jjajjpus may be traced extending
from the circumference to the centre of the disc as in the so-called
doubling of the flowers in the members of the same family. Thus,
according to A. de Jussieu,^^ the abortion is only partial in Cartha-
mus creticus, but more extended in C. lanatus ; for in this species
only two or three of the central seeds are furnished with a pappus,
the surix)unding seeds being either quito naked or furnished with a
few hairs ; and lastly in C. tinctorius, even the central seeds are
destitute of pappus, and the abortion is complete.

With animals and plants under domestication, when an organ
disappears, leaving only a rudiment, the loss has generally been
sudden, as with hornless and tailless breeds ; and such cases may be
ranked as inherited monstrosities. But in some few cases the loss
has been gradual, and has been effected partly by selection, as
with -the rudimentary combs and wattles of certain fowls. We
have also seen that the wings of some domesticated birds have been
slightly reduced l)y disuse, and the great reduction of the wings
in certain silk-moths, with mere rudiments left, has jirobably been
aided by disuse.

W^ith species in a state of nature, rudimentary organs are
extremely common. Such organs are generally variable, as
several naturalists have observed ; for, being useless, they are
not regulated by natural selection, and they are more or less
liable to reversion. The same rule certainly holds good with

«« Mr. Beaton, in 'Journal of Hor- 1862, p. 233.
ticulture,' May 21, 18(31, p. 13.3. ^* ' Annales du Museum,' torn, ri

*' Lecoq, ' De la Fecondation,' p. 319.

308 LAWS OF VAKIATION. Chap. XXIY.

parts which, have becoine rudimentary under domestication.
We do not know through what steps under nature rudimentary
organs have passed in being reduced to their present condition ;
but we so incessantly see in species of the same group the
finest gradations between an organ in a rudimentary and
perfect state, that we are led to believe that the passage must
have been extremely gradual. It may be doubted whether a
change of structure so abrupt as the sudden loss of an organ
would ever be of service to a species in a state of nature ; for
the conditions to which all organisms are closely adapted
usually change very slowly. Even if an organ did suddenly
disappear in some one individual by an arrest of development,
intercrossing with the other individuals of the same species
would tend to cause its partial reappearance ; so that its
final reduction could only be effected by some other means.
The most probable view is, that a part which is now rudi-
mentary, was formerly, owing to changed habits of life, used
less and less, being at the same time reduced in size by
disuse, until at last it became quite useless and superfluous.
But as most parts or organs are not brought into action
during an early period of life, disuse or decreased action will
not lead to their reduction until the organism arrives at a
somewhat advanced age ; and from the principle of inheritance
at corresponding ages the reduction will be transmitted to
the offspring at the same advanced stage of growth. The
part or organ will thus retain its full size in the embryo,
as we know to be the case with most rudiments. As soon as
a part becomes useless, another princij^le, that of economy of
growth, wdll come into play, as it would be an advantage to
an organism exposed to severe competition to save the de-
velopment of any useless part; and individuals having the
|)art less developed will have a slight advantage over others.
But, as Mr. Mivart has justly remarked, as soon as a part is
much reduced, the saving from its further reduction will be
utterly insignificant ; so that this cannot be effected by
natural selection. This manifestly holds good if the part be
formed of mere cellular tissue, entailing little expenditure of
nutriment. How then can the further reduction of an already
somewhat reduced part be effected ? That this has occurred

Chap. XXIV. AERESTED DEVELOPMENT AND KUDI3IENTS. 309

repeatedly under Nature is shown by the many gradations
which, exist between organs in a perfect state and the merest
vestiges of them. Mr. Eomanes ^^ has, I think, thrown much
light on this difficult problem. His view, as far as it can be
given in a few words, is as follows : all parts are somewhat
variable and fluctuate in size round an average point. Now,
when a part has already begun from any cause to decrease, it
is very improbable that the variations should be as great in
the direction of increase as of diminution ; for its previous
reduction shows that circumstances have not been favourable
for its development ; whilst there is nothing to check varia-
tions in the opposite direction. If this be so, the long con-
tinued crossing of many individuals furnished with an organ
which fluctuates in a greater degree towards decrease than
towards increase, will slowly but steadily lead to its diminu-
tion. AVith respect to the complete and absolute abortion of
a part, a distinct principle, which will be discussed in the
chapter on pangenesis, probably comes into action.

With animals and plants reared by man there is no severe
or recurrent struggle for existence, and the principle of
economy will not come into action, so that the reduction of
an organ will not thus be aided. So far, indeed, is this from
being the case, that in some few instances organs, which are
naturally rudimentary in the parent- species, become partially
redeveloped in the domesticated descendants. Thus cows,
like most other ruminants, properly have four active and two
rudimentary mammaB ; but in our domesticated animals, the
latter occasionally become considerably developed and yield
milk. The atrophied mammse, which, in male domesticated
animals, including man, have in some rare cases grown to full
size and secreted milk, perhaps offer an analogous case. The
hind feet of dogs naturally include rudiments of a fifth toe,
and in certain large breeds these toes, though still rudimentary,

^^ I suggested in 'Nature' (vol. viii. natural selection would, owing to
pp. 432, 505) that with organisms intercrossing, slowly but steadily
subjected to unfavourable conditions decrease. In three subsequent corn-
all the parts would tend towards munications to 'Nature* (March 12,
reduction, and that under such cir- April 9, and July 2, 1874), Mr.
cumstances any part which was not Romanes gives his improved view.
kept up to its standard size by

310 LAWS OF VAEIATION. Chap. XXIV.

become considerably developed and are furnished with claws.
In the common Hen, the spurs and comb are rudimentary,
but in certain breeds these become, independently of age or
disease of the ovaria, well developed. The stallion has
canine teeth, but the mare has only traces of the alveoli, which,
as I am informed by the eminent veterinarian Mr. G. T. Brown,
frequentl}^ contain minute irregular nodules of bone. Tliese
nodules, however, sometimes become developed into imperfect
teeth, protruding through the gums and coated with enamel ;
and occasionally they grow to a fourth or even a third of the
length of the canines in the stallion. With plants I do not
know whether the redevelopment of rudimentary organs
occurs more frequently under culture than under nature.
Perhaps the pear-tree may be a case in point, for when wild
it bears thorns, which consist of branches in a rudimentary
condition and serve as a protection, but, when the tree is
cultivated, they are reconverted into branches.

Chap. XXV. CORRELATED VARIABILITY. 311

CHAPTER XXV.

LAWS OF VARIATIOX, COUtinUcd CORRELATED VARIABILITY,

EXPLANATIOX OF TERM CORRELATION — CONNTi:CTED WITH DEVEOLPMENT —
MODIFICATIONS CORRELATED WITH THE INCREASED OR DECREASED SIZE
OP PARTS — CORRELATED VARIATION OF HOMOLOGOUS PARTS — FEATHERED
FEET IN BIRDS ASSUMING THE STRUCTURE OP 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
BIONSTROSITIES— CORRELATION BETWEEN THE SKULL AND EARS — SKULL
AND CREST OF FEATHERS — SKULL AND HORNS — CORRELATION OF GROWTH
COMPLICATED BY THE ACCUMULATED EFFECTS OF NATURAL SELECTION —
COLOUR AS CORRELATED WITH CONSTITUTIONAL PECULIARITIES.

All parts of the organisation are to a certain extent connected
together ; but the connection may be so slight that it hardly
exists, as with compound animals or the buds on the same tree.
Even in the higher animals various parts are not at all
closely related ; for one part may be wholly suppressed or
rendered monstrous without any other part of the body
being affected. But in some cases, when one part varies,
certain other parts always, or nearly always, simultaneously
vary ; they are then subject to the law of correlated varia-
tion. The whole body is admirably co-oidinated for the pecu-
liar habits of life of each organic being, and may be said, as
the Duke of Argyll insists in his ' Eeign of Law,' to be corre-
lated for this purpose. Again, in large groups of animals
certain structures always co-exist : for instance, a peculiar
form of stomach with teeth of peculiar form, and such
structures may in one sense be said to be correlated. But
these cases have no necessary connection with the law to be
discussed in the present chapter ; for we do not know that
the initial or primary variations of the several parts were in
any way related : slight modifications or individual differ-
ences may have been preserved, first in one and then in another
part, until the final and perfectly co-adapted structure was

312 LAWS OF VARIATIl.N. CJiAi'. XXV.

acquired ; but to this subject I shall presently recur. Again,
in many groups of animals the males alone are furnished with
weapons, or are ornamented with gay colours ; and these
characters manifestly stand in some sort of correlation with
the male reproductive organs, for when the latter are de-
stroyed these characters disappear. But it was shown in the
twelfth chapter that the very same peculiarity may become
attached at any age to either sex, and afterwards be exclu-
sively transmitted to the same sex at a corresponding age.
In these cases we have inheritance limited by both sex and
age; but we have no reason for supj)osing that the original
cause of the variation was necessarily connected with the
reproductive organs, or with the age of the aifected being.

In cases of true correlated variation, we are sometimes able
to see the nature of the connection ; but in most cases it is
hidden from us, and certainly diifers in difterent cases. We
can seldom say which of two correlated parts first varies,
and induces a change in the other ; or whether the two are
the effects of some common cause. Correlated variation is
an important subject for us ; for when one part is modified
through continued selection, either by man or under nature,
other parts of the organisation will be unavoidably modified.
From this correlation it ap23arently follows that with our
domesticated animals and plants, varieties rarely or never
differ from one another by a single character alone.

One of the simplest cases of correlation is that a modification
which arises during an early stage of growth tends to influ-
ence the subsequent develojDment of the same part, as well as of
other and intimately connected parts. Isidore Geoffrey Saint-
Hilaire states ^ that this may constantly be observed with
monstrosities in the animal kingdom ; and Moquin-Tandon ^
remarks, that, as with plants the axis cannot become mon-
strous without in someway affecting the organs subsequently
produced from it, so axial anomalies are almost always

^ ' Hist, des Anomalies,' torn. iii. p. on the Morpholo2;y of the Cephalous

392. Prof. Huxley applies the same Mollusca, in ' Phil. Transact.,' 1853,

principle in accounting for the re- p. 56.

markable, though normal, difierences ^ ' Elements de Teratologic Veg.,

in the arrangement of the nervous 1841, p. 13.
sjstem in the Mollusca, in his paper

CiiAP. XXY. CORliELATED VAEIABILI'IT. ol3

accompanied by deviations of structure in the appended parts.
"\Ve shall presently see that with short-muzzled races of the
dog certain histological changes in the basal elements of the
bones arrest their development and shorten them, and this
affects the position of the subsequently developed molar teeth.
it is i^robable that certain modifications in the larvai of
insects w^ould affect the structure of the mature insects. But
we must be careful not to extend this view too far, for
during the normal course of development, certain species pass
through an extraordinary course of change, whilst other and
closely allied species arrive at maturity with little change
of structure.

Another simple case of correlation is that with the increased
or decreased dimensions of the whole body, or of any parti-
cular part, certain organs are increased or diminished in
number, or are otherwise modified. Thus pigeon-fanciers have
gone on selecting pouters for length of body, and we have
seen that their vertebree are generally increased not only in
size but in number, and their ribs in breadth. Tumblers have
been selected for their small bodies, and their ribs and primary
wing-feathers are generally lessened in number. Fantails have
been selected for their large widely-expanded tails, with nu-
merous tail-feathers, and the caudal vertebrse are increased in
size and number. Carriers have been selected for length of
beak, and their tongues have become longer, but not in strict
accordance with the length of beak. In this latter breed and
in others having large feet, the number of the scutellBs on the
toes is greater than in the breeds with small feet. Many
similar cases could be given. In Germany it has been
observed that the period of gestation is longer in large than
in small breeds of cattle. With our highlj-improved
breeds of all kinds, the periods of maturity and of repro-
duction have advanced with respect to the age of the
animal; and, in correspondence with this, the teeth are
now developed earlier than formerly, so that, to the surprise
of agriculturists, the ancient rules for judging of the age of
an animal by the state of its teeth are no longer trustworthy.^

■^ Prof. J. B. Simonds, on the Age of the Ox, Sheep, &c. quoted in ' Gard
Chronicle,' 185+, p. 588.

314 LAWS OF VARIATION. Chap. XXV.

Correlated Variation of Homologous Parts. — Parts wliicli are
liomologons tend to vary in the same manner; and this is
what might have been expected, for snch parts are identical
in form and structure during an early period of embryonic
development, and are exposed in the egg or womb to similar
conditions. The symmetry, in most kinds of animals, of the
corresponding or homologous organs on the right and left
sides of the body, is the simplest case in point ; but this
S3anmetry sometimes fails, as with rabbits having only one
ear, or stags with one horn, or with many-horned sheep
which sometimes carry an additional horn on one side of their
heads. With flowers which haA^e regular corollas, all the petals
generally vary in the same manner, as we see in the com
plicated and symmetrical pattern, on the flowers, for instance,
of the Chinese pink ; but with irregular flowers, though the
petals are of course homologous, this S3^mmetry often fails,
as with the varieties of the Antirrliinum or snajodragon, or
that variety of the kidney-bean (Phaseolus) which has a
white standard-petal.

In the Vertebra ta the front and hind limbs are homologous,
and they tend to vary in the same manner, as we see in long
and short legged, or in thick and thin legged races of the
horse and dog. Isidore Geofii'oy* has remarked on the ten-
dency of supernumerary digits in man to appear, not only on
the right and left sides, but on the upper and lower extremi-
ties. Meckel has insisted ^ that, when the muscles of the arm
depart in number or arrangement from their proper type, they
almost always imitate those of the leg ; and so conversely the
varying muscles of the leg imitate the normal muscles of the
arm.

In several distinct breeds of the pigeon and fowl, the legs
and the two outer toes are heavily feathered, so that in the
trumpeter pigeon they appear like little wings. In the
feather-legged bantam the "boots" or feathers, which grow from
the outside of the leg and generally from the two outer toes,
have, according to the excellent authority of Mr. Hewitt,*^

* ' Hist, des Anomalies,' torn. i. p. torn. i. p. 635.

674. . « 'The Poultry Book,' by W, B

* Quoted by Isid. Geoffroy, ibid., Tegetmeier, 1866, p. 250.

Chap. XXV. CORRELATED VARIABILITY. 315

been seen to exceed the wing-featliers in length, and in one
case were actually nine and a half inches long ! As Mr.
Blyth has remarked to me, these leg-feathers resemble the
primary wing-feathers, and are totally unlike the fine down
which naturally grows on the legs of some birds, such as
grouse and owls. H*ence it may be suspected that excess of
food has first given redundancy to the plumage, and then
that the law of homologous Tariation has led to the develop-
ment of feathers on the legs, in a position corresponding with
those on. the wing, namel}'", on the outside of the tarsi and
toes. I am strengthened in this belief by the following
curious case of correlation, which for a long time seemed to
me utterly inexplicable, namely, that in pigeons of any breed,
if the legs are feathered, the two outer toes are partially
connected by skin. These two outer toes correspond with
our third and fourth toes."^ Now, in the wing of the pigeon
or of any other bird, the first and fifth digits are aborted ; the
second is rudimentary and carries the so-called " bastard-
wing ;" whilst the third and fourth digits are completely united
and enclosed by skin, together forming the extremity of the
wing. So that in feather-footed pigeons, not only does the
exterior surface support a row of long feathers, like wing-
feathers, b'lt the very same digits which in the wing are
completely united b}'' skin become partially united by skin in
the feet ; and thus by the law of the correlated variation of
homologous parts we can understand the curious connection
of feathered legs and membrane between the two outer toes.

Andrew Knight ^ has remarked that the face or head and
the limbs usually vary together in general proportions.
Compare, for instance, the limbs of a dray and race horse, or
of a grej^iound and mastiff. What a monster a greyhound
would appear with the head of a mastiif ! The modem
bulldog, however, has fine limbs, but this is a recently-selected
character. From the measurements given in the sixth

^ Naturalists differ with respect Lyceum of Nat. Hist, of New York/

to the homologies of the digits of vol. x., 1872, p. 16.
birds ; but several uphold the view * A. Walker on Intermarriage,

above advanced. See on this subject 1838, p. 160.
Dr. E. S. Morse in ' Annals of the

316 LAWS OF VAEIATION. Chap. XXV.

cliapter, we see tliat in several breeds of the pigeon the length
of the beak and the size of the feet are correlated. The view
which, as before exj)lained, seems the most probable is, that
disuse in all cases tends to diminish the feet, the beak
becoming at the same time shorter through correlation ; but
that in some few breeds in which length of beak has been a
selected point, the feet, notwithstanding disuse, have increased
in size through correlation. In the following case some kind
of correlation is seen to exist between the feet and beak :
several specimens have been sent to Mr. Bartlett at different
times, as hybrids between ducks and fowls, and I have seen
one ; these were, as might be expected, ordinary ducks in a
semi-monstrous condition, and in all of them the swimming;-
web between the toes was quite deficient or much reduced,
and in all the beak was narrow and ill-shaped.

With the increased length of the beak in pigeons, not only
the tongue increases in length, but likewise the orifice of the
nostrils. But the increased length of the orifice of the
nostrils jDerhaps standi in closer correlation with the develop-
ment of the corrugated skin or Avattle at the base of the beak,
for when there is much wattle round the eyes, the eyelids are
greatly increased or even doubled in length.

There is apparently some correlation even in colour between
the head and the extremities. Thus with horses a large white
star or blaze on the forehead is generall}^ accompanied by white
feet.^ AYith white rabbits and cattle, dark marks often
co-exist on the tips of the ears and on the feet. In black
and tan dogs of ditlerent breeds, tan-coloured spots over the
eyes and tan-coloured feet almost invariably go together.
These latter cases of connected colouring may be due either
to reversion or to analogous variation, — subjects to which I
shall hereafter return, — but this does not necessarily determine
the question of their original correlation. Mr. H. W. Jackson
informs me that he has observed many hundred white-footed
cats, and he finds that all are more or less conspicuously
marked with white on the front of the neck or chest.

• 'The Farrier and Naturalist,* me that about three-fourths of white*
vol. i., 1828, p. 456. A gentleman laced horses have white legs.
who has attended to this point, tells

CiiAi'. XXV. c(;rrelated variability. 317

The lo])ping forwards and downwards of the immense ears
of fancy rabbits seems partly due to the disuse of the muscles,
and partly to the weight and length of the ears, wliich have
been increased by selection during many generations. Kow,
with the increased size and changed direction of the ears not
only has the bony auditory meatus become changed in outline,
direction, and greatly in size, but the whole skull has been
slightly modified. This could be clearl}^ seen in " half-lops "
— that is, in rabbits with only one ear lopping forward — for
the opposite sides of their skulls were not strictly S3^mmetrical.
This seems to me a curious instance of correlation, between
hard bones and organs so soft and flexible, as well as so
unimportant under a physiological point of view, as the
external ears. The lesult no doubt is largely due to mere
mechanical action, that is, to the weight of the ears, on the
same principle that the skull of a human infant is easily
modified by pressure.

The skin and the appendages of hair, feathers, hoofs, horns,
and teeth, are homologous over the whole body. Every one
knows that the colour of the skin and that of the hair usually
vary together; so that Virgil advises the shepherd to look
whether the mouth and tongue of the ram are black, lest the
lambs should not be purely white. The colour of the skin
and hair, and the odour emitted by the glands of the skin,
are said ^° to be connected, even in the same race of men.
Generally the hair varies in the same way all over the body
in length, fineness, and curliness. The same rule holds good
with feathers, as we see with the laced and frizzled breeds
both of fowls and pigeons. In the common cock the feathers
on the neck and loins are always of a particular shape, called
hackles : now in the Polish breed, both sexes are characterised
by a tuft of feathers on the head, and through correlation
these feathers in the male always assume the form of hackles.
The wing and tail-feathers, though arising from parts not
homologous, vary in length together ; so that long or short
winged pigeons generally have long or short tails. The case
of the Jacobin-pigeon is more curious, for the wing and tail
feathers are remarkably long ; and this apparently has arisen
*" Godron, ' Sur I'Espece,' torn. ii. p. 217.

318

LAWS OF VARIATION.

Chap. XXV.

in correlation with tiie elongated and reversed feathers on the
back of the neck, which form the hood.

The hoofs and hair ai'e homologous appendages; and a
careful observer, namely Azara,^^ states that in Paraguay
horses of various colours are often born with their hair curled
and twisted like that on the head of a negro. This peculiarity
is strongly inherited. But what is remarkable is that the
hoofs of these horses " are absolutely like those of a mule."
The hair also of their manes and tails is invariably much
shorter than usual, being only from four to twelve inches in
length ; so that curliness and shortness of the hair are here,
as with the negro, apparently correlated.

With respect to the horns of sheep, Youatt ^^ remarks that
" multiplicity of horns is not found in any breed of much value;
" it is generally accompanied by great length and coarseness
" of the fleece." Several tropical breeds of sheep which are
clothed with hair instead of w^ool, have horns almost like
those of a goat. Sturm ^^ expressly declares that in different
races the more the wool is curled the more the Lorns are
spirally twisted. We haA^'e seen in the third chapter, where
other analogous facts have been given, that the parent of the
Mauchamp breed, so famous for its fleece, had peculiarly
shaped horns. The inhabitants of Angora assert ^* that " only
" the wdiite goats wdiich have horns wear the fleece in the
" long curly locks that are so much admired; those which
" are not horned having a comparatively close coat." From
these cases we may infer that the hair or wool and the horns
tend to vary in a correlated manner. ^^ Those who have tried
hydropathy are aware that the frequent application of cold
water stimulates the skin ; and whatever stimulates the skin

'^ < Quadrupedes du Paraguay,'
torn. ii. p. 333.

12 On Sheep, p. 142.

*2 ' Ueber Kacen, Krouzungen,' &c.,
1825, s. 24.

^* Quoted from Conolly, in ' The
Indian Field,' Feb. 1859, vol. ii. p.
266.

** In the third chapter I have said
that " the hair and horns are so close-
ly related to each other, that they arc

apt to vary together." Dr. Wilckens
("Darwin's Theorie," 'Jahibuch
der Deutschen Viehzucht,' 1866, 1.
Heft) translates my words into " lang-
und grobhaarige Thiere sollen ge-
neigter sein, iange und viele Horner
zu bekommen," and he then justly
disputes this proposition ; but what I
have really said, in accordance with
the authorities just quoted, may, I
think, be trusted.

Chap. XXV. CORKELATED VARIABILITY. 319

tends to increase the growth of the hair, as is well shown in
the abnormal growth of hair near old inflamed surfaces.
Kow, Professor Low ^^ is convinced that with the different
races of British cattle thick skin and long hair depend on
the humidity of the climate which they inhabit. We can
thus see how a humid climate might act on the horns — in the
first place directly on the skin and hair, and secondly b}^
correlation on the horns. The presence or absence of horns^
m.oreover, both in the case of sheep and cattle, acts, as wall
presently be shown, by some sort of correlation on the skull.
With respect to hair and teeth, Mr. Yarrell ^'^ found many
of the teeth deficient in three hairless " Egyptian dogs," and
in a hairless terrier. The incisors, canines, and the premolars
suffered most, but in one case all the teeth, except the large
tubercular molar on each side, were deficient. With man
several striking cases have been recorded ^^ of inherited bald-
ness with inherited deficiency, either complete or partial, of
the teeth. I may give an analogous case, communicated to me
by Mr. W. Wedderburn, of a Hindoo family in Scinde, in which
ten men, in the course of four generations, were furnished, in
both jaws taken together, with only four small and weak
incisor teeth and with eight posterior molars. The men thus
affected have very little hair on the body, and become bald
early in life. They also suffer much during hot weather from
excessive dryness of the skin. It is remarkable that no
instance has occurred of a daughter being thus affected ; and
this fact reminds us how much more liable men are in England
to become bald than w^omen. Though the daughters in the
above family are never affected, they transmit the tendency
to their sons ; and no case has occurred of a son transmitting
it to his sons. The affection thus appears only in alternate
generations, or after longer intervals. There is a similar con-
nection between hair and teeth, according to Mr. Sedgwick,

'® 'Domesticated Animals of the '' ' Proceedings Zoolog. Soc.,' 1833

British Islands,' pp. 307, 368. Dr. p. 113.

Wilckens argues (' Landwirth. Wo- '* Sedgwick, ' Brit, and F'>rfcign

chenbJatt,* Nr. 10, 1869) to the same M^dico-Chirurg. Review,' April, 1863,

etfect with respect to domestic animals p. 453.
m Germany.

320 LAWS OF VAKIATION. Chap. XXV.

in those rare cases in wliicli tlie hair has been renewed in old
age, for this has " "usually been accompanied by a renewal of
the teeth." I have remarked in a former part of this volume
that the great reduction in the size of the tusks in domestic
boars probably stands in close relation with their diminished
bristles, due to a certain amount cf protectioD ; and that the
reappearance of the tusks in boars, which have become feral
and are fully exposed to the weather, probably depends on the
reappearance of the biistles. I may add, though not strictly
connected with our present point, that an agriculturist ^^
asserts that " pigs with little hair on their bodies are most
" liable to lose their tails, showing a weakness of the
" tegumental structure. It may be prevented by crossing
" with a more haiiy breed."

In the previous cases deficient hair, and teeth deficient in
number or size, are apparently connected. In the following
cases abnormally redundant hair, and teeth either deficient or
redundant, are likewise connected. Mr. Crawfurd -° saw at
the Burmese Court a man, thirt}^ 3'ears old, with his whole
bod}'", except the hands and feet, covered with straight silky
hair, which on the shoulders and spine was five inches in
length. At birth the ears alone were covered. He did not
arrive at puberty, or shed his milk teeth, until tw^enty years
old; and at this period he acquired five teeth in the upper jaw,
namel}'", four incisors and one canine, and four incisor teeth in
the lower jaw ; all the teeth were small. This man had a
daughter who w^as born with hair wdthin her ears ; and the
hair soon extended over her bod3\ When Captain Yule'-^^
visited the Court, he found this girl grown up; and she
presented a strange appearance with even her nose densely
covered with soft hair. Like her father, she was furnished
with incisor teeth alone. The King had "with difficulty
bribed a man to marry her, and of her two children, one, a
boy fourteen months old, had hair growing out of his ears,
with a beard and moustache. This strange peculiarity has,
therefore, been inherited for three generations, with the

»» <Gard. Chronicle,' 1849, p. 205. 21 < Narrative of a Mission to the

20 ' Embassy to the Court of Ava,' Court of Ava in 1855,' p. 94.
rol. i. p. 320.

Chap. XXV. CORRELATED VARIABILITY. 321

molar teeth deficient in the grandfather and mother; whether
these teeth would likewise fail in the infant could not then
be told.

A parallel case of a man fift3"-fi.ve years old, and of his son,
with their faces covered with hair, has recently occurred in
Eussia. Dr. Alex. Brandt has sent me an account of this
case, together with specimens of the extremely fine hair
from the cheeks. The man is deficient in teeth, possessing
only four incisors in the lower and two in the upper jaw.
His son, about three jesus old, has no teeth except four
lower incisors. The case, as Dr. Brandt remarks in his letter,
no doubt is due to an arrest of development in the hair and
teeth. ^^ e here see how independent of the ordinary con-
ditions of existence such arrests must be, for the lives of a
Russian peasant and of a native of Burmah are as different
as possible.^^

Here is another and somewhat different case communicated
to me by Mr. Wallace on llie authority of Dr. Purland, a
dentist : Julia Pastrana, a Spanish dancer, was a remarkably
fine woman, but she had a thick masculine beard and a
hairy forehead ; she was photographed, and her stuffed skin
was exhibited as a show ; but what concerns us is, that she
had in both the upper and lower jaw an irregular double set
of teeth, one row being placed within the other, of which Dr.
Purland took a cast. From the redundancy of teeth her
mouth projected, and her face had a gorilla-like appearance.
These cases and those of the hairless dogs forcibly call to
mind the fact, that the tw^o orders of mammals — namely, the
Edentata and Cetacea — which are the most abnormal in their
dermal covering, are likewise the most abnormal either by
deficiencj^ or redundancy of teeth.

The organs of sight and hearing are generally admitted to
be homologous with one another and with various dermal
appendages ; hence these parts are liable to be abnormally
affected in conjunction. Mr. White Cowper says " that in all
*' cases of double microphthalmia brought under his notice he

22 I owe to the kindness of M. both of whom have since been ex^
Chauman, of St. Petersburg, excellent hibited in Paris and London,
photographs of this vnaxx and his son,

322

LAWS OF VAETATION.

Chap. XXV.

" lias at the same time met with defective development of
" the dental system." Certain forms of blindness seem to be
associated vs^ith the colour of the hair ; a man with black
hair and a woman with light-coloured hair, both of sound
constitution, married and had nine children, all of whom
were born blind ; of these children, five " with dark hair
" and brown iris were afflicted with amaurosis ; the four
" others, with light-coloured hair and blue iris, had amaurosis
" and cataract conjoined." Several cases could be given,
showing that some relation exists between various affections
of the eyes and ears ; thus Liebreich states that out of 241
deaf-mutes in Berlin, no less than fourteen suffered from the
rare disease called pigmentary'' retinitis. Mr. White Cowper
and Dr. Earle have remarked that inability to distinguish
different colours, or colour-blindness, " is often associated
" with a corresponding inability to distinguish musical
" sounds." ^^

Here is a more curious case : white cats, if they have blue
eyes, are almost always deaf. I formerly thought that the
rule was invariable, but I have heard of a few authentic ex-
cej)tions. The first two notices were published in 1829, and
relate to English and Persian cats : of the latter, the Rev. W.
T. Bree possessed a female, and he states, " that of the. offspring
" produced at one and the same birth, such as, like the mother,
" were entirely white (with blue eyes) were, like her, invari-
" ably deaf; while those that had the least speck of colour on
" their fur, as invariably possessed the usual faculty of
" hearing." ^* The Eev. W. Darwin Fox informs me that he
has seen more than a dozen instances of this correlation in
English, Persian, and Danish cats ; but he adds " that, if one

2' These statements are taken
from Mr. Sedgwick, in the ' Medico-

Chirurg

Review,' July, 1861, p.
198 ; April, 1863, pp. 455 and 458.
Liebreich is quoted by Professor
Devay, in his ' Mariages Consan-
guins,' 1862, p. 116.

2* Loudon's ' Mag. of Nat. Hist.,'
vol. i., 1829, pp. 66, 178. See also
Dr. P. Lucas, ' L'Hered. Nat.,' torn. i.
p. 428, on the inheritance of deafness

in cats. Mr. Lawson Tait states
('Nature,' 1873, p. 323) that only
male cats are thus affected ; but this
must be a hasty generalisation. The
first case recorded in England by Mr.
Bree related to a female, and Mr.
Fox informs me that he has bred
kittens from a white female with
blue eyes, which was completely deaf;
he has also observed otlier females in
the same condition.

Chap. XXV. CORRELATED VARIABIIJTV. 323

*' eye, as I have several times observed, be not blue, the cat
" hears. On the other hand, I have never seen a white cat
" with eyes of the common colour that was deaf." In France
Dr. Sicliel -^ has observed during twenty years similar facts;
he adds the remarkable case of the iris beginning, at the end
of four months, to grow dark-coloured, and then the cat first
began to hear.

This case of correlation in cats has struck many persons
as marvellous. There is nothing unusual in the relation be-
tween blue eyes and white fur ; and we have already seen
that the organs of sight and hearing are often simultaneously
affected. In the present instance the cause probably lies in
a slight arrest of development in the nervous system in con-
nection with the sense-organs. Kittens during the first nine
days, whilst their eyes are closed, appear to be completely
deaf; I have made a great clanging noise with a poker and
shovel close to their heads, both when they were asleep and
awake, without producing an}^ effect. The trial must not
be made by shouting close to their ears, for they are, even
when asleep, extremely sensitive to a breath of air. Now, as
long as the eyes continue closed, the iris is no doubt blue,
for in all the kittens which I have seen this colour remains
for some time after the eyelids open. Hence, if we suppose
the development of the organs of sight and hearing to be
arrested at the stage of the closed eyelids, the eyes would
remain permanently blue and the ears w^ould be incapable of
perceiving sound ; and we should thus understand this curious
case. As, however, the colour of the fur is determined long
before birth, and as the blueness of the eyes and the whiteness
of the fur are obviously connected, we must believe that some
primary cause acts at a much earlier period.

The instances of correlated variability hitherto given have
been cLiefly drawn from the animal kingdom, and we will
now turn to plants. Leaves, sepals, petals, stamens, and
pistils are all homologous. In double flowers we see that
the stamens and pistils vary in the same manner, and assume
the form and colour of the petals. In the double columbine
[Aquilegia vulgaris), the successive whorls of stamens are con-

2* 'Annales des Sc. N^at.' Zoolog., 3rd series, 1847, torn. viii. p. 239,

32 1 LAWS OF VAEIATION. Chap. XXV.

verted into cornucopias, wliicli are enclosed within one another
and resemble the true petals. In hose-in-hose flowers the
sepals mock the petals. In some cases the flowers and leaves
vary together in tint : in all the varieties of the common pea,
which have purj)le flowers, a i^iii'ple mark may be seen on
the stipules.

M. Faivre states that with the varieties of Primula sinensis
the colour of the flower is evidently correlated with the colour
of the under side of the leaves ; and he adds that the varieties
with fimbriated flowers almost alwa^^s have voluminous,
balloon-like calyces.^^ With other plants the leaves and fruit
or seeds vary together in colour, as in a curious pale-leaved
variety of the sj^camore, which has recently been described ia
France,^'^ and as in the purple-leaved hazel, in which the leaves,
the husk of the nut, and the pellicle round the kernel are all
coloured purple.^^ Pomologists can predict to a certain extent,
from the size and appearance of the leaves of their seedlings,
the probable nature of the fruit ; for, as Van Mons remarks,^'-^
variations in the leaves are generally accompanied by some
modification in the flower, and consequently in the fruit. In
the Serpent melon, which has a narrow tortuous fruit above a
3'ard in length, the stem of the plant, the peduncle of the
female flower, and the middle lobe of the leaf, are all elon-
gated in a remarkable manner. On the other hand, several
varieties of Cucurbita, which have dwarfed stems, all pro-
duce, as Naudin remarks, leaves of the same peculiar shape.
Mr. G. Maw informs me that all the varieties of the scarlet
Pelargoniums which have contracted or imperfect leaves haA^e
contracted flowers : the difference between " Brilliant " and
its parent " Tom Thumb " is a good instance of this. It ma}^
be suspected that the curious case described b}^ Eisso,^° of a
variety of the Orange which produces on the young shoots
rounded leaves with winged j)etioles, and afterwards elongated
leaves on long but wingless petioles, is connected with the

2^ 'Revue des Cours Scientifiques,' stances, * Des Varietes,' 1865, p. 72.
June 5, 1869, p. 430. 29 « Arbres Fruitiers,' 1836, torn, ii,

27 'Gardener's Chron.,' 1864, p. pp. 204, 226.
1202. 3** ' Annales du Museum,' torn, xx

?^ Verlot gives seyej-aj other in- p, 188,

Chap. XXV. CORRELATED VARIABILITY. 325

remarkable change in form and nature which the fruit under-
goes during its development.

In the following instance we have the colour and the form
of the petals apparently correlated, and both dependent on
the nature of the season. An observer, skilled in the subject,
writes,^^ " I noticed, during the year 1842, that every
" Dahlia of which the colour had any tendency to scarlet,
" was deeply notched — indeed, to so great an extent as to
*' give the petals the appearance of a saw ; the indentures
" were, in some instances, more than a quarter of an inch
" deep." Again, Dahlias which have their petals tipped
with a different colour from the rest of the flower are very
inconstant, and during certain years some, or even all the
flowers, become uniformly coloured; and it has been observed
with several varieties,^^ that when this happens the petals
grow much elongated and lose their proper shape. This,
however, may be due to reversion, both in colour and form,
to the aboriginal species.

In this discussion on correlation, we have hitherto treated
of cases in which we can partly understand the bond of
connection; but I will now give cases in which we can-
not even conjecture, or can only very obscurely see, the
nature of the bond. Isidore Geoffrey Saint- Hilaire, in his
work on Monstrosities, insists, ^^ " que certaines anomalies
*' coexistent rarement entr'elles, d'autres frequemment, d'autres
" enfin presque constamment, malgre la difference tres-grande
" de leur nature, et quoiqu'elles puissent paraitre completement
" independantes les unes des autres." We see something
analogous in certain diseases : thus in a rare affection of the
renal capsules (of which the functions are unknown), the
skin becomes bronzed ; and in hereditary syphilis, as I hear
from Sir J. Paget, both the milk and the second teetli
assume a peculiar and characteristic form. Professor Eol-
leston, also, informs me that the incisor teeth are sometimes

" ' Gardeners Chron.,' 1843, p. p 402, See also M, Camille Dareste,

877. ' Recherches sur les Conditions,* &c,

« Ibid., 1845, p. 102, 1863, pp. 16, 48.
■* 'Hist, des Anomalies,' torn. iii.

36

326 LAWS OF VAEIATION. Chap. XX Y.

furnislied with a vascular rim in correlation with intra-
pulmonary deposition of tubercles. In other cases of phthisis
and of cyanosis the nails and finger-ends become clubbed like
acorns. I believe that no explanation has been offered of
these and of many other cases of correlated disease.

What can be more curious and less intelligible than the
fact previously given, on the authority of Mr. Tegetmeier,
that young j)igeon8 of all breeds, w^hich when mature have
white, yellow, silver-blue, or dun-coloured plumage, come out
of the egg almost naked ; whereas pigeons of other colours
when first born are clothed with plenty of down ? White
Pea-fowls, as has been observed both in England and France,^^
and as I have myself seen, are inferior in size to the common
coloured kind ; and this cannot be accounted for by the
belief that albinism is always accompanied by constitutional
weakness ; for white or albino moles are generally larger
than the common kind.

To turn to more important characters : the niata cattle of
the Pampas are remarkable from their short foreheadi?
upturned muzzles, and curved lower jaws. In the skull the
nasal and premaxillary bones are much shortened, the
maxillaries are excluded from any junction with the nasals,
and all the bones are slightly modified, even to the plane of
the occiput. From the analogous case of the dog, hereafter
to be given, it is probable that the shortening of the nasal
and adjoining bones is the proximate cause of the other
modifications in the skull, including the upward curvature
of the lower jaw, though we cannot follow out the st(,])s by
which these changes have been effected.

Polish fowls have a large tuft of feathers on their heads ;
and their skulls are perforated by numerous holes, so that a
pin can be driven into the brain without touching any bone.
That this deficiency of bone is in some way connected with
the tuft of feathers is clear from tufted ducks and geese
likewise having perforated skulls. The case would probably
be considered by some anthers as one of balancement or
compensation. In the chapter on Fowls, I have shown that

'* Rev. E. S. Dixon, ' Ornamental Geoffroy, ' Hist. Anomalies,' torn. i.
Poultry,' 1848, p. Ill; Isidore p. 211.

Chap. XXV. COKRELATED VAEIABILTTT. 327

with Polish fowls the tuft of feathers was probably at first
email; by continued selection it became larger, and then
rested on a fibrous mass; and finally, as it became still
larger, the skull itself became more and more protuberant
until it acquired its present extraordinary structure. Through
correlation with the protuberance of the skull, the shape
and even the relative connection of the premaxillary and
nasal bones, the shape of the orifice of the nostrils, the
breadth of the frontal bone, the shape of the post-lateral
processes of the frontal and squamosal bones, aad the
direction of the bony cavity of the ear, have all been
modified. The internal configuration of the skull and the
whole shape of the brain have likewise been altered in a
truly marvellous manner.

After this case of the Polish fowl it would be superfluous
to do more than refer to the details previously given on the
manner in which the changed form of the comb has affected
the skull, in various breeds of the fowl, causing by correlation
crests, protuberances, and dej)ressions on its surface.

With our cattle and sheep the horns stand in close con-
nection with the size of the skull, and with the shape of the
frontal bones ; thus Cline^^ found that the skull of a horned
ram weighed five times as much as that of a hornless ram of
the same age. When cattle become hornless, the frontal
bones are " materially diminished in breadth towards the
•' poll ; " and the cavities between the bony plates " are not so
" deep, nor do they extend beyond the frontals."^^

It may be well here to pause and observe how the effbcts of
correlated variability, of the increased use of parts, and of the
accumulation of so-called spontaneous variations through
natural selection, are in many cases inextricably commingled.
We may borrow an illustration from Mr. Herbert Spencer, who
remarks that, when the Irish elk acquired its gigantic horns,
weighing above one hundred pounds, numerous co-ordinated
changes of structure would have been indispensable, — namely,
a thickened skull to carry the horns ; strengthened cervical

*' * On the Breeding of Domestic Animals,' 1829, p. 6.
"6 Youatt on Cattle, 1834, p. 283,

328 LAWS OF VARIATION. Chap. XXV.

vertetrse, with, strengtliened ligaments ; enlarged dorsal
vertebr^TB to support the neck, with j^owefful fore-legs and
feet; all these parts being supplied with proper muscles,
blood-vessels, and nerves. How then could these admirably
co-ordinated modifications of structure have been acquired?
According to the doctrine which I maintain, the horns of the
male elk were slowly gained through sexual selection, — that
is, by the best-armed males conquering the worse-armed, and
leaving a greater number of descendants. But it is not at all
necessary that the several parts of the body should have
simultaneously varied. Each stag presents individual charac-
teristics, and in the same district those which had slightly
heavier horns, or stronger necks, or stronger bodies, or were
the most courageous, would secure the greater number of
does, and consequently have a greater number of offspring.
The offspring would inherit, in a greater or less degree, these
same qualities, would occasionally intercross with one another,
or with other individuals varying in some favourable manner ;
and of their offspring, those which were the best endowed in
any respect would continue multiplexing ; and so onwards,
always progressing, sometimes in one direction, and some-
times in another, towards the excellently co-ordinated struc-
ture of the male elk. To make this clear, let us reflect on
the probable steps, as shown in the twentieth chapter, b}'-
which our race and dray horses have arrived at their present
state of excellence ; if we could view the whole series of
intermediate forms between one of these animals and an early
unimproved progenitor, we should behold a vast number of
animals, not equally improved in each generation throughout
their entire structure, but sometimes a little more in one
point, and sometimes in another, yet on the whole gradually
approaching in character to our present race or dray horses,
which are so admirably fitted in the one case for fleetness and
in the other for draught.

Although natural selection would thus ^^ tend to give to

^^ Mr. Herbert Spencer (' Principles " faculties multiply, and as fast as

of Biology,' 1864, vol. i. pp. 452, *•' the number of organs that co-

468) takes a different view; and in one "operate in any given function

place remarks : " We have seen reason " increases, indirect equilibration

" to think that, as fast as essential " through natural selection becomefl

Chap. XXV. CORRELATED VARIABILITY. 329

the male elk its present structure, yet it is probable tbat the
inherited effects of use, and of the mutual action of part on
part, have been equally or more important. As the horns
gradually increased in weight the muscles of the neck, with
the bones to which tbey are attached, would increase in size
and strength ; and these parts would react on the body and
legs. Nor must we overlook the fact that certain parts of
the skull and the extremities would, judging by analogy,
tend from the first to vary in a correlated manner. The
increased weight of the horns would also act directly on the
skull, in the same manner as when one bone is removed in
the leg of a dog, the other bone, which has to carry the whole
weight of the body, increases in thickness. But from the
fact given with respect to horned and hornless cattle, it is
probable that the horns and iskull would immediately act on
each other through the principle of correlation. Lastly, the
growth and subsequent wear and tear of the augmented
muscles and bones would require an increased supply of
blood, and consequently increased supply of food ; and this
again would require increased powers of mastication, diges-
tion, respiration, and excretion.

Colour as Correlated loitli Constitutional Peculiarities.

It is an old belief that with man there is a connection
between complexions and constitution ; and I find that some
of the best authorities believe in this to the present day.^^
Thus Dr. Beddoe by his tables shows ^^ that a relation exists
between liability to consumption and the colour of the hair,
eyes, and skin. It has been afiirmed **^ that, in the French
army which invaded Russia, soldiers having a dark complexion
from the southern parts of Europe, withstood the intense

" less and less capable of producing our domesticated quadrupeds and

"specific adaptations; and remains birds.

" fully capable only of maintaining ^* Dr. Prosper Lucas apparently

" the general fitness of constitution disbelieves in any such connection ;

" to conditions." This view that ' L'Hered. Nat.,' tom. ii. pp. 88-94.

natural selection can do little in ^^ ' British Medical Journal,' 1862,

modifying the higher animals sur- p. 433.

prises me, seeing that man's selection *" Boudin, * Ge'ograph. Medicala,*

has undoubtedly effected much with tom. i. p. 4u6.

330 LAWS OF VARIATION, Chap. XXV.

cold better than those with lighter complexions from the
north ; but no doubt such statements are liable to error.

In the second chapter on Selection I have given several
cases proving that with animals and plants differences in
colour are correlated with constitutional differences, as shown
by greater or less immunity from certain diseases, from the
attacks of parasitic plants and animals, from scorciiing by the
sun, and from the action of certain poisons. When all the
individuals of any one variety possess an immunity of this
nature, we do not know that it stands in any sort of correlation
with their colour; but when several similarly coloured
varieties of the same species are thus characterised, whilst
other coloured varieties are not thus favoured, we must believe
in the existence of a correlation of this kind. Thus, in the
United States purple-fruited plums of many kinds are far
more affected by a certain disease than green or yellow-fruited
varieties. On the other hand, yellow-fleshed peaches of
various kinds suffer from another disease much more than the
white-fleshed varieties. In the Mauritius red sugar-canes
are much less affected b}'' a particular disease than the white
canes. White onions and verbenas are the most liable to
mildew ; and in Spain the green- fruited grapes suffered from
the vine-disease more than other coloured varieties. Dark-
coloured pelargoniums and verbenas are more scorched by the
sun than varieties of other colours. Eed wheats are believed
to be hardier than white ; and red-flowered hyacinths were
more injured during one particular winter in Holland than
other coloured varieties. With animals, white terriers suffer
most from the distemper, white chickens from a parasitic
worm in their trache£e, white pigs from scorching by the sun,
and white cattle from flies ; but the caterpillars of the silk-
moth which yield white cocoons suffered in France less from
the deadly parasitic fungns than those j)roduciiig yellow silk.

The cases of immunity from the action of certain vefj;etabie
poisons, in connexion with colour, are more interesting, and
are at present wholly inexplicable. I have already given a
remarkable instance, on the authority of Professor \Vyman, of
all the hogs, excepting those of a black colour, suffering
severely in Virginia from eating the root of the Lachnanthcs

Chap. XXV. CORRELATED VARIABILITY. 331

iinctoria. According to Spinola and others,*^ buckwlieat {Poly-
gonum fagopyrum), when in flower, is highly injurious to white
or white-spotted pigs, if thej are exposed to the heat of the
sun, but is quite innocuous to black pigs. According to two
accounts, the Hypericum crispum in Sicily is poisonous to white
sheep alone ; their heads swell, their wool falls off, and they
often die ; but this plant, according to Lecce, is poisonous
only when it grows in swamps ; nor is this improbable, as
we know how readily the poisonous principle in plants is
influenced by the conditions under which they grow.

Three accounts have been published in Eastern Prussia, of
w^hite and white- sjxjtted horses being greatly injured by
eating mildewed and honeyde wed vetches ; ever}^ spot of skin
bearing white hairs becoming inflamed and gangrenous. The
Rev. J. Eodwell informs me that his father turned out about
fifteen cart-horses into a field of tares which in parts swarmed
with black aphides, and which no doubt were hone^^le wed, and
probably mildewed; the horses, with two excej)tions, were
chestnuts and bays with white marks on their faces and
pasterns, and the white parts alone swelled and became angry
scabs. The two bay horses with no white marks entirely
escaped all injury. In. Guernsey, when horses eat fool's
parsley (JEthusa cynapium) they are sometimes violently
purged ; and this plant " has a peculiar effect on the nose
■■' and lips, causing deep cracks and ulcers, particularly on
*' horses with white muzzles."*^ With cattle, independently
of the action of any poison, cases have been published by
Youatt and Erdt of cutaneous diseases with much consti-
tutional dnsturbance (in one instance after exposure to a hot
sun) affecting every single point which bore a white hair, but
completely passing over ^ther parts of the body. Similar
cases have been observed with horses.*^

*^ This fact and the followiug cases, eating buckwheat; whilst black or

when not stated to the contrary, are dark-woolled individuals are not in

taken from a very curious paper by the least affected.
Prof. Heusinger, in ' Wochenschrift ^^ I\Ir. Mogford, in the ' Veteri-

fiir Heilkunde,' May, 1846, s. 277. narian,' quoted in 'The Field,' Jan.

Settegast (; Die Thierzucht,' 1868, }). 22, 18G1, p. 545.
39) says that white or white-spotted *^ ' Edinburgh Veterinary Journal,'

sheep suiier like pigs, or even die from Oct. 1860, p. 347.

332 LAWS OF VARIATION. Chap. XXV.

We thus see that not only do those parts of the skin which
bear white hair dijffer in a remarkable manner from those
bearing hair of any other colour, but that some great consti-
tutional difference must be correlated with the colour of the
hair ; for in the above-mentioned cases, vegetable poisons
caused fever, swelling of the head, as well as other sjTnptoms,
and even death, to all the white, or white-spotted animals.

Chap. XXVL FUSION OF HOMOLOGOUS PARTS. 333

CHAPTER XXVI.

LAWS OF VARIATION", Continued — summary.

THE FUSION OF HOMOLOGOUS PARTS — THE VARIABILITY OP MULTIPLE AND
HOMOLOGOUS PARTS — COMPENSATION OP GROWTH — MECHANICAL PRESSURE
— RELATIVE POSITION OF FLOWEHS WITH RESPECT TO THE AXIS, AND OF
SEEDS IN THE OVARY, AS INDUCING VARIATION — ANALOGOUS OR PARALLEL
VARIETIES — SUMMARY OF THE THPvEE LAST CHAPTERS.

TJie Fusion of Homologous Parts. — Geoffroy Saint-Hilaire
formerly propounded what he called la loi de Vaffiniie de soi
pour soi, which has been discussed and illustrated by his son,
Isidore, with respect to monsters in the animal kingdom,^
and by Moquin-Tandon, with respect to monstrous plants.
'I'his law seems to imiily that homologous parts actually
attract one another and then unite. Xo doubt there are
many wonderful cases, in which such parts become intimately
fused together. This is perhaj)S best seen in monsters with
two heads, which are united, summit to summit, or face to
face, or Janus-like, back to back, or obliquely side to side.
In one instance of two heads united almost face to face, but a
little obliquely, four ears were developed, and on one side a
perfect face, which was manifestly formed by the fusion of
two half-faces. Whenever two bodies or two heads are
united, each bone, muscle, vessel, and nerve on the line of
junction appears as if it had sought out its fellow, and had be-
come completely fused with it. Lereboullet,^ who carefully
studied the development of double monsters in fishes, observed
in fifteen instances the steps by which two heads gradually
became united into one. In all such cases it is now thought
by the greater number of ca|)able judges that the homolo-
gous parts do not attract each other, but that in the words
of Mr. Lowne : ^ "As union takes jjlace before the difierentia-

^ * Hist, des Anomalies,' 1832, torn. ' ' Catalogue of the Teratological

L pp. 22, 537-556 ; torn. iii. p. 462. Series in the Museum of the R. Coll.

^ • Comptes Rendus,' 1855, pp. 855, of Surgeons,' 1872, p. xvi.
1029.

334 LAWS OF VAEIATION. Chap. XXYI,

" tion of distinct organs occurs, these are formed in continuity
" with, each other." He adds that organs already differenti-
ated probably in no case become united to homologous ones.
M. Dareste does not speak* quite decisively against the law of
8oi pour soi, but concludes by sa3^ing, " On se rend parfaitement
" compte de la formation des monstres, si Ton admet que les
" embryons qui se soudent ajopartiennent a un meme ceuf ;
" qu'ils s'unissent en meme temps qu'ils se forment, et que la
" soudure ne se produit que pendant la premiere periode de la
" vie embryonnaire, celle ou les organes ne sont encore con-
" stitues que par des blastemes homogenes."

By whatever means the abnormal fusion of homologous
paits is effected, such cases throw light on the frequent
presence of organs which are double during an embryonic
period (and throughout life in other and lower members of the
same class) but which afterwards unite by a normal process
into a single medial organ. In the vegetable kingdom Moquin-
Tandon^ gives a long list of cases, showing how frequently
homologous parts, such as leaves, jDctals, stamens, and j)istils,
flowers, and aggregates of homologous parts, such as buds,
as well as fruit, become blended, both normally and abnor-
mally, with perfect symmetry into one another.

The Variabilit]/ of Multiple and Homologous Parts. — Isidore
Geoffrey^ insists that, -vvhen any part or organ is repeated
many times in the same animal, it is particularly liable to
vary both in number and structure. With respect to number,
the proposition may, I think, be considered as fully estab-
lished ; but the evidence is chiefly derived from organic
beings living under their natural conditions, with which we
are not here concerned. Whenever such parts as the vertebn^
or teeth, the ra^'s in the fins of fishes, or the feathers in
the tails of birds, or petals, stamens, pistils, or seeds, are very
numerous, the number is generally variable. AVith respect to
the structure of multiple parts, the evidence of variability is
not so decisive ; but the fact, as far as it may be trusted,

*' Archives de Zoolog. Exper.,' Jan., ^ 'Hist, des Anomalies,' tona. iii,

1874, p. 78. pp. 4, 5, 6.

* ' Tevatologie Veg.,' 1841, livre iii.

CJUAP. XXVI. COMPENSATION. 335

probably depends on multiple parts being of less physiological
importance than single parts ; consequently their structure
has been less rigorously guarded by natural selection.

Compensation of GrowtJi, or Balancement, — This law, as
applied to natural species, was propounded by Goethe and
Geofifroy Saint-Hilaire at nearly the same time. It implies
that, when much organised matter is used in building up
some one part, other parts are starved and become reduced.
Several authors, especially botanists, believe in this law ;
others reject it. As far as I can judge, it occasionally holds
good ; but its importance has probably been exaggerated. It
is scarcely possible to distinguish between the supposed
effects of such compensation, and the effects of long-continued
selection which may lead to the augmentation of one part,
and simultaneously to the diminution of another. Anyhow,
there can be no doubt that an organ may be greatly increased
without any corresponding diminution of an adjoining part.
To recur to our former illusti-ation of the Irish elk, it may be
asked what part has suffered in consequence of the immense
development of the horns ?

It has already been observed that the struggle for existence
does not bear hard on our domesticated productions, and con-
sequently the principle of economy of growth will seldom
come into play, so that we ought not to expect to find with
them frequent evidence of compensation. We have, however,
some such cases. Moquin-Tandon describes a monstrous bean,^
in which the stipules were enormously developed, and the
leaflets apparently in consequence completely aborted ; this
case is interesting, as it represents the natural condition of
Latliyrus aphaca, with its stipules of great size, and its leaves
reduced to mere threads, which act as tendrils. De Can-
dolle^ has remarked that the varieties of Baphamis sativus
which have small roots yield numerous seed containing much
oil, whilst those with large roots are not productive in oil ;
and so it is with Brassica asperifolia. The varieties of

7 'Teratologie Veg.,' p. 156. See 1875, p. 202.
also my book on ' The Movements and * 'Menioires du Museum,' &c.,

Habits of Climbing Plants,' 2nd edit, torn. viii. p. 178.

336 LAWS OF VARIATION. Chap. XXVL

Cuciirhita jpepo which bear large fmit yield a small crop,
according to Naudin; whilst those producing small fruit
yield a vast number. Lastly, I have endeavoured to show in
the eighteenth chapter that with many cultivated plants
unnatural treatment checks the full and j)roper action of the
reproductive organs, and they are thus rendered more or less
sterile ; consequently, in the way of compensation, the fruit
becomes greatly enlarged, and, in double flowers, the petals
are greatly increased in number.

With animals, it has been found difficult to produce cows
which yield much milk, and are afterwards capable of fatten-
ing well. With fowls which have large top-knots and beards
the comb and wattles are generally much reduced in size ;
though there are exceptions to this rule. Perhaps the entire
absence of the oil-gland in fantail pigeons may be connected
with the great development of their tails.

Meclianical Pressure as a Cause of Modifications. — In some
few cases there is reason to believe that mere mechanical
pressure has affected certain structures. Yrolik and Weber ^
maintain that the shape of the human head is influenced by
the shape of the mother's pelvis. The kidneys in different
birds differ much in form, and St. Ange ^° believes that this
is determined by the form of the pelvis, which again, no
doubt, stands in close relation with their power of locomotion.
In snakes, the viscera are curiously displaced, in comparison
with their position in other vertebrates ; and this has been
attributed by some authors to the elongation of their bodies ;
but here, as in so many previous cases, it is impossible to
disentangle a direct result of this kind from that consequent
on natural selection. Godron has argued ^^ that the abortion
of the spur on the inner side of the flowers in Corydalis, is
caused by the buds at a very early period of growth whilst
underground being closely pressed against one another and
against the stem. Some botanists believe that the singular
diiference in the shape both of the seed and corolla, in the

* Prichard, * Phjs. Hist, of Man- series, torn, xix. p. 327.
kind,' 1851, vol. i. p. 824. " 'Comptes Reudus,' Dec. 1864, p

" 'Annales des Sc. Nat.,' 1st 1039.

Chap. XXVL KELATIVE POSITION OF PARTS 337

interior and exterior florets in certain Compositous and
Umbelliferous plants, is due to the pressure to which the
inner florets are subjected ; but this conclusion is doubtful.

The facts just given do not relate to domesticated produc-
tions, and therefore do not strictly concern us. But here is
a more appropriate case : H. Miiller ^^ has shown that in
shortfaced races of the dog some of the molar teeth are placed
in a slightly different position to that which they occupy
in other dogs, especially in those having elongated muzzles ;
and as he remarks, any inherited change in the arrangement
of the teeth deserves notice, considering their classificatory
importance. This difference in position is due to the shorten-
ing of certain facial bones and the consequent want of space ;
ayid the shortening results from a peculiar and abnormal state
of the embryonal cartilages of the bones.

Helative Position of Flowers with respect to the Axis, and of Seeds
in the Ovary, as inducing Variation.

In the thirteenth chapter various peloric flowers were described,
and their production was shown to be due either to arrested
development, or to reversion to a primordial condition. Moquin-
Tandon has remarked that the flowers which stand on the summit
of the main stem or of a lateral branch are more liable to become
peloric than those on the sides ; ^^ and he adduces, amongst other
instances, that of Teucrium campanulatum. In another Labiate
plant grown by me, viz. the Gahohdolon luteum, the peloric flowers
were always produced on the summit of the stem, where flowers are
not usually borne. In Pelargonium, a single flower in the truss is
frequently peloric, and when this occurs I have during several years
invariably observed it to be the central flower. This is of such
frequent occurrence that one observer ^^ gives the names of ten
varieties flowermg at the same time, in every one of which the
central flower was peloric. Occasionally more than one flower in
the truss is peloric, and then of course the additional ones must be
lateral. These flowers are interesting as showing how the whole
structure is correlated. In the common Pelargonium the upper
sepal is produced into a nectary which coheres with the flower-
peduncle; the two upper petals differ a little in shape from the
three lower ones, and are marked with dark shades of colour ; the
stamens are graduated in length and upturned. In the peloric

" " Ueber fotale Rachites," ' Wiirz- " ' Teratologie Veg.,' p. 192.

burger Medicin. Zeitschnft,' 18(30, B. '* 'Journal of Horticulture,' Julj

i. s. 265. 2nd, 1861, p. 253.

338 LAWS OF VARIATION. Chap. XXVI.

flowers, tlie nectary aborts ; all the petals become alike both in shape
and colour; the stamens are generally reduced in number and
become straight, so that the whole flower resembles that of the
allied genus Erodium. The correlation between these changes is
well shown when one of the two upper petals alone loses its dark
mark, for in this case the nectary does not entirely abort, but is
usually much reduced in length.^^

Morren has described ^^ a marvellous flask-shaped flower of the
Calceolaria, nearly four inches in length, which was almost completely
})eloric ; it grew on the summit of the plant, with a normal flower
on each side; Prof. Westwood also has described ^^ three similar
peloric flowers, which all occupied a central position on the flower-
branches. In the Orcliideous genus, Phalainopsis, the terminal
flower has been seen to become peloric.

In a Laburnum-tree I observed that about a fourth part of the
racemes produced terminal flowers which had lost their papilionaceous
structure. These were produced after almost all the other flowers
on the same racemes had withered. The most perfectly pelorised
examples had six petals, each marked with black strise like those on
the standard-petal. The keel seemed to resist the change more than
the other petals, Dutrochet has described ^^ an exactly similar case
in France, and I believe these are the only two instances of pelorism
in the laljurnum which have been recorded. Dutrochet remarks
that the racemes on this tree do not properly produce a terminal
flower, so that (as in the case of the Galeobdolon) their position as
well as structure are both anomalies, which no doubt are in some
manner related. Dr. Masters has briefly described another leguminous
plant,^'* namely, a species of clover, in which the vippermost and central
flowers were regular or had lost their papilionaceous structure.
In some of these plants the flower-heads were also proliferous.

Lastly, Linaria produces two kinds of peloric flowers, one having
simple petals, and the other having them all spurred. The two
forms, as Naudin remarks,^*^ not rarely occur on the same plant, but
in this case the spurred form almost invariably stands on the
summit of the spike.

The tendency in the terminal or central flower to become peloric
more frequently than the other flowers, probably results from " the
" bud which stands on the end of a shoot receiving the most sap ;
" it grows out into a stronger shoot than those situated lower

" It would be worth trial to fer- culture,' Feb. 24, 1863, p. 152.

tilise with the same pollen the central *^ ' Gardener's Chronicle,' 1866, p.

and lateral flowers of the pelargo- 612. For the Phalaenopsis, see ibid.,

nium, or of other highly cultivated 1867, p. 211.

plants, protecting them of course ^* Memoires . . des Vegetaux/

from insects : then to sow the seed 1837, torn. ii. p. 170.

separately, and observe whether the '^ ' Journal of Horticulture,' July

one or the other lot of seedlings 23, 1861, p. 311.

varied the most. *" 'Nouvelles Archives du Museum,

'^ Quoted in 'Journal of Horti- torn. i. p. 137.

Chap. XX VX RELATIVE POSITION OF PARTS. 339

** down." -^ I have discussed tlie connection between pelorism and
a central position, partly because some few plants are known nor-
mally to yjroduce a terminal flower different in structure from
the lateral ones ; but chiefly on account of the following case, in
which we see a tendency to variability or to reversion connected
with the same position. A great judge of Auriculas ^^ states that
when one throws up a side bloom it is pretty sure to keep its
character; but that if it grows from the centre or heart of the
plant, whatever the colour of the edging ought to be, " it is just as
" likely to come in any other class as in the one to which it properly
" belongs." This is so notorious a fact, that some florists regularly
pinch off the central trusses of flowers. Whether in the highly
improved varieties the departure of the central trusses from their
proper type is due to reversion, I do not know. Mr. Dombrain
insists that, whatever may be the commonest kind of imperfection
in each variety, this is generally exaggerated in the central truss.
Thus one variety " sometimes has the fault of producing a little
" green floret in the centre of the flower," and in central blooms these
become excessive in size. In some central blooms, sent to me by
Mr. Dombrain, all the organs of the flower were rudimentary in
structure, of minute size, and of a green colour, so that by a little
further change all would have been converted into small leaves.
In this case we clearly see a tendency to prolification — a term which
I may explain, for those who have never attended to botany, to mean
the production of a branch or flower, or head of flowers, out of
another flower. Now Dr. Masters ^^ states that the central or upper-
most flower on a plant is generally the most liable to prolification.
Thus, in the varieties of the Auricula, the loss of their proper
character and a tendency to prolification, also a tendency to pro-
lification with pelorism, are all connected together, and are due
either to arrested development, or to reversion to a former condition.

The following is a more interesting case ; Metzger ^* cultivated in
Germany several kinds of maize brought from the hotter parts of
America, and he found, as previously described, that in two or three
generations the grains became greatly changed in form, size, and
colour ; and with respect to two races he expressly, states that in
the first generation, whilst the lower grains on each head retained
their proper character, the uppermost grains already began to assume
that character which in the third generation all the grains acquired.
As we do not know the aboriginal parent of the maize, we cannot
tell whether these changes are in any way connected with reversion.

In the two following cases, reversion comes into play and is de-
termined by the position of the seed in the capsule. The Blue Imperial
pea is the offspring of the Blue Prussian, and has larger seed and

" Hugo von Mohl, 'The Vegetable 1862, April 29th, p. 83.

Cell,' Eng. tr., 1852, p. 76. ^3 'Transact. Linn. Soc.,' vol. xxiii.,

" The Rev. H. H. Dombrain, in 1861, p. 360.

' Journal of Horticulture,' 1861, June ^* ' Die Getreidearteu,' 1845, s. 208,

4th, p. 174; and June 25th, p. 234; 209.

840 LAWS OF VARIATION. Chap. XXVI

broader pods than its parent. Now Mr. Masters, of Canterbury, a
careful observer and a raiser of new varieties of the pea, states '^^
that the Blue Imperial always has a strong tendency to revert to
its parent-stock, and the reversion "occurs in this manner: the
*' last (or uppermost) pea in the pod is frequently much smaller
" than the rest ; and if these small peas are carefully collected and
** sown separately, very many more, in proportion, will revert to
*' their origin, than those taken from the other parts of the pod."
Again, M. Chate ^^ says that in raising seedling stocks he succeeds
in getting eighty per cent, to bear double flowers, by leaving only
a few of the secondary branches to seed; but in addition to this,
" at the time of extracting the seeds, the upper portion of the pod
" is separated and placed aside, because it has been ascertained
" that the plants coming from the seeds situated in this portion of
" the pod, give eighty per cent, of single flowers." Now the pro-
duction of single-flowering plants from the seed of double-flowering
plants is clearly a case of reversion. These latter facts, as well as
the connection between a central position and pelorism and pro-
lification, show in an interesting mauner how small a difference —
namely, a little greater or less freedom in the flow of sap towards
one part of the plant — determines important changes of structure.

Analogous or Parallel Variation. — By this term I mean
tliat similar characters occasionall}'' make their appearance
in the several varieties or races descended from the same
species, and more rarely in the offspring of widely distinct
species. We are here concerned, not as hitherto with the
causes of variation, but with the results ; but this discussion
could not have been more conveniently introduced elsewhere.
The cases of analogous variation, as far as their origin is
concerned, may be grouped, disregarding minor subdivisions,
under two main heads ; firstl}'-, those due to unknown causes
acting on similarly constituted organisms, and which con-
sequently have varied in a similar manner ; and secondly,
those due to the reaj)pearance of characters which were
possessed by a more or less remote progenitor. But these
two main divisions can often be separated only conjec-
turally, and graduate, as we shall presently see, into each
other.

Under the first head of analogous variations, not due to reversion,
we have the many cases of trees belonging to quite different orders
which have produced pendulous and fastigate varieties. The beech,

2^ ' Gardener's Chronicle,' 1850, p. ^^ Quoted in ' Gardener's Chron.,*

198. 1866, T,. 74.

CuAP. XXVI. ANALOGOUS VARIATION. 341

hazel, and barberry have given rise to purple-leaved varieties ; and,
as Bernhardi remarks,-^^ a multitude of plants, as distinct as possible,
have yielded varieties with deeply-cut or laciniated leaves. Varieties
descended from three distinct species of Brassica have their stems,
or so-called roots, enlarged into globular masses. The nectarine is
the oflfspring of the peach ; and the varieties of peaches and
nectarines offer a remarkable parallelism in the fruit being white,
red, or yellow fleshed — in being clingstones or freestones — in the
flowers being large or small — in the leaves being serrated or crenated,
furnished with globose or reniform glands, or quite destitute of
glands. It should be remarked that each variety of the nectarine
has not derived its character from a corresponding variety of the
peach. The several varieties also of a closely allied genus, namely
the apricot, differ from one another in nearly the same parallel
manner. There is no reason to believe that any of these varieties
have merely reacquired long-lost characters ; and in most of them
this certainly is not the case.

Three species of Cucurbita have yielded a multitude of races
which correspond so closely in character that, as Naudin insists,
they may be arranged in almost strictly parallel series. Several
varieties of the melon are interesting from resembling, in important
characters, other species, either of the same genus or of allied genera ;
thus, one variety has fruit so like, both externally and internally,
the fruit of a perfectly distinct species, namely, the cucumber, as
hardly to be distinguished from it; another has long cylindrical
fruit twisting about Hke a serjoent ; in another the seeds adhere to
portions of the pulp; in another the fruit, when ripe, suddenly
cracks and falls into pieces ; and all these highly remarkable
peculiarities are characteristic of species belonging to allied genera.
We can hardly account for the appearance of so many unusual
characters by reversion to a single ancient form; but we must
believe that all the members of the family have inherited a nearly
similar constitution from an early progenitor. Our cereal and many
other plants offer similar cases.

With animals we have fewer cases of analogous variation, inde-
pendently of direct reversion. We see something of the kind
in the resemblance between the short-muzzled races of the dog,
such as the pug and bull-dog ; in feather-footed races of the fowl,
pigeon, and canary-bird ; in horses of the most difierent races pre-
senting the same range of colour ; in all black-and-tan dogs having
tan-coloured eye-spots and feet, but in this latter case reversion
may possibly have played a part. Low has remarked '■^^ that several
breeds of cattle are " sheeted," — that is, have abroad band of white
passing round their bodies like a sheet ; this character is strongly
inherited, and sometimes originates from a cross ; it may be the
first step in reversion to an early type, for, as was shown in the

*^ ' Uel)er den Begriff der Pflanzen- ^8 t Domesticated Animals,* 1845,

art,' 1834, s. 14. p. 351.

342 LAWS OF VAEIATION. Chap. XXVI

third chapter, white cattle with dark ears, dark feet and tip of tail,
formerly existed, and now exist in feral or semi-feral condition in
several quarters of the world.

Under our second main division, namely, of analogous variations
due to reversion, the best cases are afibrded by pigeons. In all the
most distinct breeds, sub-varieties occasionally appear coloured
exactly like the parent rock-pigeon, with black wing-bars, white
loins, banded tail, &c. ; and no one can doubt that these characters
are due to reversion. So with minor details ; tui'bits properly have
white tails, but occasionally a bird is born with a dark- coloured and
banded tail ; pouters properly have their primary wing-feathers
white, but not rarely a " sword-flighted " bird appears, that is, one
with the few first primaries dark-coloured ; and in these cases we
have characters proper to the rock-pigeon, but new to the breed,
evidently ajDpearing from reversion. In some domestic varieties
the wing-bars, instead of being simply black, as in the rock-pigeon,
are beautifally edged with different zones of colour, and they then
present a striking analogy with the wing-bars in certain natural
species of the same family, such as Fhaps chalcojptera ; and this
may probably be accounted for by all the species of the family
being descended from the same remote progenitor and having a ten-
dency to vary in the same manner. Thus, also, we can perhaps
understand the fact of some Laugher-pigeons cooing almost like
turtle-doves, and for several races having peculiarities in their
flight, since certain natural species (viz., C. torquutrix undpalumbun),
display singular vagaries in this respect. In other cases a race,
instead of imitating a distinct species, resembles some other race ;
thus, certain runts tremble and slightly elevate their tails, like fan-
tails ; and turbits inflate the upper part of their oesophagus, like
pouter-pigeons.

It is a common circumstance to find certain coloured marks per-
sistently characterising all the species of a genus, but differing much
in tint ; and the same thing occurs with the varieties of the pigeon :
thus, instead of the general plumage being blue, with the wing-bars
black, there are snow-white varieties with red bars, and black varie-
ties with white bars ; in other varieties the wing-bars, as we have
seen, are elegantly zoned with different tints. The Spot pigeon is
characterised by the whole plumage being white, excepting a spot
on the forehead and the tail ; but these parts may be red, yellow, or
black. In the rock-pigeon and in -many varieties the tail is blue,
with the outer edges of the outer feathers white ; but in the sub-
variety of the monk-pigeon we have a reversed style of coloration,
for the tail is white, except the outer edges of the outer feathers,
which are black.^^

With some species of birds, for instance with gulls, certain
coloured parts appear as if almost washed out, and I have observed
exactly the same appearance in the terminal dark tail-bar in certain

^^ Beohbtein, ' Xaturgoschichte Deiitschlands,' Band iv., 1795, s. 31.

Chap. XXVI. ANALOGOUS VARIATION. 343

pigeons, and in the whole plumage of certain varieties of the duck.
Analogous facts in the vegetable kingdom could be given.

Many sub-varieties of the pigeon have reversed and somewhat
lengthened feathers on the back part of their heads, and this is
certainly not due to reversion to the parent-species, which shows
no trace of such structure : but when we remember that sub-varie-
ties of the fowl, turkey, canary-bird, duck, and goose, all have either
topknots or reversed feathers on their heads ; and when we remember
that scarcely a single large natural group of birds can be named, in
which some members have not a tuft of feathers on their heads, we
may suspect that reversion to some extremely remote form has
come into action.

Several breeds of the fowl have either spangled or pencilled
feathers; and these cannot be derived from the parent- species, the
Uullus hankiva ; though of course it is possible that one early pro-
genitor of this species may have been spangled, and another pen-
cilled. But, as many gallinaceous birds are either spangled or pen-
cilled, it is a more probable view that the several domestic breeds
of the fowl have acquired this kind of plumage from all the
members of the family inheriting a tendency to vary in a like
manner. The same principle may account for the ewes in certain
breeds of sheep being hornless, like the females of some other
hollow-horned ruminants ; it may account for certain domestic cats
having slightly-tufted ears, like those of the lynx ; and for the skulls
of domestic rabbits often differing from one another in the same
characters by which the skulls of the various sjDecies of the genus
Lepus differ.

I will only allude to one other case, already discussed. Now
that we know that the wdld parent of the ass commonly has striped
legs, we may feel confident that the occasional appearance of stripes
on the legs of the domestic ass is due to reversion ; but this will not
account for the lower end of the shoulder-stripe being sometimes
angularly bent or slightly forked. So, again, when we seen dun
and other coloured horses with stripes on the spine, shoulders, and
legs, we are led, from reasons formerly given, to believe that they
reappear through reversion to the wild parent-horse. But when
horses have two or three shoulder- stripes, with one of them occa-
sionally forked at the lower end, or when they have stripes on their
faces, or are faintly striped as foals over nearly their whole bodies,
with the stripes angularly bent one under the other on the fore-
head, or irregularly branched in other parts, it would be rash to
attribute such diversified characters to the reappearance of those
proper to the aboriginal wild horse. As three African species of
the genus are much striped, and as we have seen that the crossing
of the unstriped species often leads to the hybrid offspring being
conspicuously striped — bearing also in mind that the act of crossing
certainly causes the reappearance of long-lost characters — it is
a more probable view that the above-specified stripes are due to
reversion, not to the inmaediate wild jjareut-horse, but to the stri])ed
progenitor of the whole genus.

344 LAWS OF VAKIATION. C^av XXVI

I have discussed this subject of analogous variation at con-
Biderable length, because it is well known that the varieties
of one species frequently resemble distinct species — a fact in
perfect harmony with the foregoing cases, and explicable on
the theory of descent. Secondly, because these facts are
important from showing, as remarked in a former chapter,
that each trifling variation is governed by law, and is deter-
mined in a much higher degree by the nature of the organi-
sation, than by the nature of the conditions to which the
varying being has been exposed. Thirdly, because these facts
are to a certain extent related to a more general law, namely,
that which Mr. B. D. Walsh ^o has called the "Law of
Equable Variability" or, as he explains it, " if any given cha-
" racter is very variable in one species of a group, it will tend
" to be variable in allied species ; and if any given character
" is perfectly constant in one species of a group, it will tend
" to be constant in allied species."

This leads me to recall a discussion in the chapter on
Selection, in which it was shown that with domestic races,
which are now undergoing rapid improvement, those parts
or characters vary the most, which are the most valued.
This naturally follows from recently selected characters con-
tinually tending to revert to their former less improved
standard, and from their being still acted on by the same
agencies, whatever these may be, which first caused the cha-
racters in question to vary. The same principle is applicable
to natural species, for, as stated in my ' Origin of Species,'
generic characters are less variable than specific characters;
and the latter are those which have been modified by varia-
tion and natural selection, since the period when all the
species belonging to the genus branched oif from a common
progenitor, whilst generic characters are those which have
remained unaltered from a much more remote epoch, and ac-
cordingly are now less variable. This statement makes a
near approach to Mr. Walsh's law of Equable Variability.
Secondary sexual characters, it may be added, rarely serve to
characterise distinct genera, for they usually difi'er much in
the species of the same genus, and they are highly variable

^0 ' Proc. Entomolos:. Soc. of Philadelphia,' Oct. 1863, p. 213.

Chap. XXVI. SUMMARY. 345

in tlie individuals of the same species ; we have also seen in
the earlier chapters of this work how variable secondary sexual
characters become under domestication.

Summary of the three previous Chapters on the Laws of Variation.

In the twenty-third chapter we saw that changed con-
ditions occasionally, or even often, act in a definite manner
on the organisation, so that all, or nearly all, the individuals
thus exposed become modified in the same manner. But
a far more frequent result of changed conditions, whether
acting directly on the organisation or indirectly through the
reproductive system, is indefinite and fluctuating variability.
In the three last chaj)ters, some of the laws by which such
variability is regulated have been discussed.

Increased use adds to the size of muscles, together with
the blood-vessels, nerves, ligaments, the crests of bone and
the whole bones, to which they are attached. Increased
functional activity increases the size of various glands, and
strengthens the sense-organs. Increased and intermittent
pressure thickens the epidermis. A change in the nature of
the food sometimes modifies the coats of the stomach, and
augments or decreases the length of the intestines. Continued
disuse, on the other hand, weakens and diminishes all parts
of the organisation. Animals which during many generations
have taken but little exercise, have their lungs reduced in
size, and as a consequence the bony fabric of the chest and
the whole form of the body become modified. With our
anciently domesticated birds, the wings have been little used,
and they are slightly reduced ; with their decrease, the crest
of the sternum, the scapulae, coracoids, and furculum, have all
been reduced.

With domesticated animals, the reduction of a part from
disuse is never carried so far that a mere rudiment is left ;
whereas we have reason to believe that this has often occurred
under nature ; the effects of disuse in this latter case being
aided by economy of growth, together with the intercrossing
of many varying individuals. The cause of this dijBference
between organisms in a state of nature, and under domestica-
tion, probabl}'' is that in the latter case there has not been

346 LAWS OF VARIATION. Chap. XXVI.

time sufficient for any very great change, and that the
principle of economy of growth does not come into action.
On the contrary, structures which are rudimentary in the
parent-S]3ecies, sometimes become partially redeveloped in our
domesticated productions. Such rudiments as occasionally
make their appearance under domestication, seem always to
he the result of a sudden arrest of development ; nevertheless
they are of interest, as showing that rudiments are the relies
of organs once perfectly developed.

Corporeal, periodical, and mental habits, though the latter
have been almost passed over in this work, become changed
under domestication, and the changes are often inherited.
Such changed habits in an organic being, especially when
living a free life, would often lead to the augmented or
diminished use of various organs, and consequently to their
modification. From long-continued habit, and more especi-
ally from the occasional birth of individuals with a slightly
different constitution, domestic animals and cultivated plants
become to a certain extent acclimatised or adapted to a
climate different from that proper to the parent-species.

Through the principle of correlated variabilit}'', taken in
its widest sense, when one part varies other parts var}^ either
simultaneously, or one after the other. Thus, an organ modi-
fied during an early embryonic period affects other parts
subsequently developed. When an organ, such as the beak,
increases or decreases in length, adjoining or correlated j^arts,
as the tongue and the orifice of the nostrils, tend to vary in the
same manner. When the whole body increases or decreases
in size, various parts become modified ; thus, with j)igeons
the ribs increase or decrease in number and breadth. Homo-
logous parts which are identical during their early develop-
ment and are exposed to similar conditions, tend to vary
ill the same or in some connected manner, — as in the case of
the right and left sides of the body, and of the front and
hind limbs. So it is with the organs of sight and hearing ;
for instance, white cats with blue eyes are almost always
deaf. There is a manifest relation throughout the body be-
tween the skin and various dermal appendages, such as hair,
feathers, hoofs, horns, and teeth. In Paraguay, horses with

CiiAr. XXVI. SUMMAKY. 347

curly hair hav^e hoofs like those of a mule ; the wool and the
horns of sheep often vary together ; hairless clogs are deficient
in their teeth ; men with redundant hair have abnormal teeth,
either by deficiency or excess. Birds wdth long wing-feathers
usually have long tail-feathers. When long feathers grow
from the outside of the legs and toes of pigeons, the two
outer toes are connected by membrane ; for the whole leg
tends to assume the structure of the wing. There is a mani-
fest relation between a crest of feathers on the head and a
marvellous amount of change in the skull of various fowls ;
and in a lesser degree, between the greatly elongated, lopping
ears of rabbits and the structure of their skulls. With plants,
the leaves, various parts of the flower, and the fruit, often
vary together to a correlated manner.

In some cases we find correlation Avithout being able even
to conjecture what is the nature of the connection, as with
various monstrosities and diseases. This is likewise the case
with the colour of the adult pigeon, in connection with the
presence of down on the young bird. Numerous curious
instances have been given of peculiarities of constitution,
in correlation with colour, as shown by the immunity of
individuals of one colour from certain diseases, from the
attacks of parasites and from the action of certain vegetable
poisons.

Correlation is an important subject ; for with species, and
in a lesser degree with domestic races, we continually find
that certain parts have been greatly modified to serve some
useful purpose ; but we almost invariably find that other
parts have likewise been more or less modified, without our
being able to discover any advantage in the change. No
doubt great caution is necessary with respect to this latter
point, for it is difficult to overrate our ignorance on the
use of various parts of the organisation ; but from what we
have seen, we may believe that many modifications are of no
direct service, having arisen in correlation with other and
useful changes.

Homologous parts during their early develojjment often
become fused together. Multiple and homologous organs
are especially liable to vary in number and probably in

348 LA.WS OF VAKIATION. Ciiap. XXVI.

form. As the supp]y of organised matter is not unlimited,
the principle of compensation sometimes comes into action ;
so that, when one part is greatly developed, adjoining parts
are apt to be reduced ; but this principle is probably of much
less importance than the more general one of the economy
of growth. Through mere mechanical pressure hard parts
occasionally affect adjoining parts. With plants the position
of the flowers on the axis, and of the seeds in the ovary, some-
times leads, through a more or less free flow of sap, to changes
of structure; but such changes are often due to reversion.
Modifications, in whatever manner caused, will be to a certain
extent regulated by that co-ordinating power, or so-called
nisusformaticus, which is in fact a remnant of that simple form
of reproduction, displaj^ed by many lowly organised beings in
their power of fissiparous generation and budding. Finally,
the effects of the laws which directly or indirectly govern
variability, may be largely regulated by man's selection, and
will so far be determined by natural selection that changes
advantageous to any race will be favoured, and disadvan-
tao;eous chano-es will be checked.

Domestic races descended from the same species, or from
two or more allied species, are liable to revert to characters
derived from their common progenitor ; and, as they inherit
a somewhat similar constitution, they are liable to vary
in the same manner. From these two causes analogous
varieties often arise. When we reflect on the several fore-
going laws, imperfectly as we understand them, and when
we bear in mind how much remains to be discovered, we need
not be surprised at the intricate and to us unintelligible
manner in which our domestic productions have varied, and
still go on varying.

Chap. XXVII. PROVISIONAL HYPOTHESIS OF PANGENESIS. 349

CHAPTEK XXVII.

PROVISIONAL HYPOTHESIS OF PANGENESIS.

PRELnilNARY REMARKS — FIRST PART : — THE FACTS TO BE CONNECTED UNDEB
A SINGLE POINT OP TIEW, NAMELY, THE VARIOUS KINDS OF REPRODUC-
TION — RE-GROWTH OF AMPUTATED PARTS — GRAFT-HYBRIDS — THE DIRECT
ACTION OF THE MALE ELEMENT ON THE FEMALE — DEVELOPMENT — THE
FUNCTIONAL INDEPENDENCE OF THE UNITS OF THE BODY — VARIABILITY
— INHERITANCE — REVERSION.

SECOND part: — STATEMENT OP THE HYPOTHESIS — HOW FAR THE NECESSARY
ASSUMPTIONS ARE IMPROBABLE — EXPLANATION BY AID OF THE HYPOTHESIS

OF THE SEVERAL CLASSES OF FACTS SPECIFIED IN THE FIRST PART

CONCLUSION.

In the previous chapters large classes of facts, such as those
bearing on bud-variation, the various forms of inheritance, the
causes and lavrs of variation, have been discussed ; and it is
obvious that these subjects, as well as the several modes of
reproduction, stand in some sort of relation to one another. I
have been led, or rather forced, to form a view which to a
certain extent connects these facts by a tangible method.
Every one would wish to explain to himself, even in an
imperfect manner, how it is possible for a character possessed
by some remote ancestor suddenly to reappear in the offspring ;
how the effects of increased or decreased use of a limb can be
transmitted to the child ; how the male sexual element can
act not solely on the ovules, but occasionally on the mother-
form; how a hybrid can be produced by the union of the
cellular tissue of two plants independently of the organs of
generation ; how a limb can be reproduced on the exact line
of amputation, wdth neither too much nor too little added ;
how the same organism may be produced by such widely
different processes, as budding and true seminal generation ;
and, lastly, how of two allied forms, one passes in the course of
it« development through the most complex metamorphoses,
and the other does not do so, though when mature both are
alike in every detail of structure. I am aware that my
view is merely a provisional hypothesis or speculation ; but
37

850

PROVISIONAL HYPOTHESIS

Chap. XXVIL

until a better one be advanced, it will serve to bring together
a multitude of facts which are at present left disconnected by
any efficient cause. As Whewell, the historian of the inductive
sciences, remarks : — " Hypotheses may often be of service to
*' science, when they involve a certain portion of incomplete-
" ness, and even of error." Under this point of view I venture
to advance the hypothesis of Pangenesis, which implies that
every separate part of the whole organisation reproduces
itself. So that OAmles, spermatozoa, and pollen-grains, — the
fertilised egg or seed, as well as buds, — include and consist of
a multitude of germs thrown off from each separate part or
unit.^

In the First Part I will enumerate as briefly as I can the
groups of facts which seem to demand connection ; but certain

' This hypothesis has been severely
criticised by many writers, and it
will be fair to give references to the
more important articles. The best
essay which I have seen is by Prof.
Delpino, entitled 'Sulla Darwiniana
Teoria della Pangenesi, 1869,' of
which a translation appeared in
'Scientific Opinion,' Sept. 29, 18(39
and the succeeding numbers. He
rejects the hypothesis, but criticises
it fairly, and I have found his criti-
cisms very useful. Mr. Mivart
(•Genesis of Species,' 1871, chap, x.)
follows Delpino, but adds no new
objections of any weight. Dr. Bastiaa
(' The Beginnings of Life,' 1872, vol. ii.
p. 98) says that the hypothesis " looks
" like a relic of the old rather than a
" fitting appanage of the new evolu-
" tion philosophy." He shows that I
ought not to have used the term
♦' pangenesis," as it had been previously
used by Dr. Gros in another sense.
Dr. Lionel Beale ('Nature,' May 11,
1871, p. 26) sneers at the whole doc-
trine with much acerbity and some
justice. Prof. Wigand (' Schrifteu der
Gesell. der gesammt. Naturwissen. zu
Marburg,' Bd. ix., 1870) considers the
hypothesis as unscientific and worth-
less. Mr. G. H, Lewes (' Fortnightly
Review,' Nov. 1, 1868, p. 503) seems
to consider that it may be useful : he

makes many good criticisms in a per-
fectly fair spirit. Mr. F. Galton, after
describing his valuable experiments
(' Proc. Royal Soc' vol. xix. p. 393) on
the intertransfusion of the blood of
distinct varieties of the rabbit, con-
cludes by saying that in his opinion
the results negative beyond all doubt
the doctrine of Pangenesis. He in-
forms me that subsequently to the
publication of his paper he continued
his experiments on a still larger scale
for two more generations, without
any sign of mongrelism showing itself
in the very numerous offspring. I
certainly should have expected that
gemmules would have been present in
the blood, but this is no necessary
part of the hypothesis, which mani-
festly applies to plants and the lowest
animals. Mr. Galton, in a letter to
' Nature '(April 27, 1871, p. 502), also
criticises various incorrect expressions
used by me. On the other hand,
several writers have spoken favour-
ably of the hypothesis, but there
would be no use in giving references
to their articles. 1 may, however,
refer to Dr. Ross* work, 'The Graft
Theory of Disease ; being an applica-
cation of Mr. Darwin's hypothesis of
Pangenesis,' 1872, as he gives several
original and ingenious discussions.

Chap. XXVII.

OF PANGENESIS.

351

subjects, not hitherto discussed, must be treated at dispropor-
tionate length. In the Second Part the hypothesis will be
given ; and after considering how far the necessary assump-
tions are in themselves improbable, we shall see whether it
serves to bring under a single point of view the various facts.

Part I.

Reproduction may be divided into two main classes, namely,
sexual and asexual. The latter is effected in many ways — by
the formation of buds of various kinds, and by fissi parous
generation, that is by spontaneous or artificial division. It is
notorious that some of the lower animals, when cut into many
pieces, reproduce so many perfect individuals : Lyonnet cut a
Nais or freshwater worm into nearly forty pieces, and these
all reproduced perfect animals.^ It k probable that segmen-
tation could be carried much further in some of the protozoa ;
and with some of the lowest plants each cell will reproduce
the parent-form. Johannes Miiller thought that there was an
important distinction between gemmation and fission ; for in
the latter case the divided portion, however small, is more
fully developed than a bud, which also is a younger formation ;
but most physiologists are now con '/inced that the two processes
are essentially alike.^ Prof. Huxley remarks, " fission is little
*' more than a peculiar mode of budding," and Prof. H. J.
Clark shows in detail that there is sometimes " a compro-
*' mise between self-division and budding." When a limb
is amputated, or when the whole body is bisected, the cut
extremities are said to bud forth ; * and as the papilla, which
is first formed, consists of undeveloped cellular tissue like
that forming an ordinary bud, the expression is apparently
correct. We see the connection of the two processes in

* Quoted by Paget, ' Lectures on
Pathology,' 1853, p. 159.

^ Dr. Lachmann, also, observes
('.Annals and Mag. of Nat. History,'
2nd series, vol. xix., 1857, p. 231)
with respect to infusoria, that " fissa-
" tion and gemmation pass into each
" other almost imperceptibly." Again,
Mr. W. C. Minor (' Annals and Mag.
of Nat. Hist.,' 3rd series, vol xi. p.

328) shows that with Annelids the
distinction that has been made be-
tween fission and budding is not a
fundamental one. Sei', also, Pro-
fessor Clark's work, ' Mind in Nature,'
New York, 1865, pp. 62, 9L

* See Bonnet. ' (Euvres d'Hist.
Nat.,' torn, v., 1781, p. 339, for
remai'ks on the budding-out of the
amputated limbs of Salamanders.

852 PPtOYISIONAL HYPOTHESIS Chap. XXVIL

anotlier way ; for Trembley observed witli the hydra, that
the reproduction of the head after amputation was checked as
soon as the animal put forth reproductive gemmae.^

Between the production, by fissiparous generation, of two
or more complete individuals, and the repair of even a very
slight injury, there is so perfect a gradation, that it is
impossible to doubt that the two processes are connected. As
at each stage of growth an amputated part is replaced by one
in the same state of development, we must also follow Sir J.
Paget in admitting, " that the powers of development from the
" embryo, are identical with those exercised for the restora-
*' tion from injuries : in other words, that the powers are the
" same by which perfection is first achieved, and by which,
" when lost, it is recovered." ^ Finally, we may conclude
that the several forms of budding, fissiparous generation, the
repair of injuries, and development, are all essentially the
results of one and the same power.

Sexual Generation. — The union of the two sexual elements
seems at first sight to make a broad distinction between
sexual and asexual generation. But the conjugation of
algae, by which process the contents of two cells unite into a
single mass capable of development, apparently gives us the
first step towards sexual union : and Pringsheim, in his
memoir on the pairing of Zoospores,"^ shows that conjugation
graduates into true sexual reproduction. Moreover, tlie now
well-ascertained cases of Parthenogenesis prove that the
distinction between sexual and asexual generation is not
nearly so great as was formerly thought ; for ova occasion-
ally, and even in some cases frequently, become developed into
perfect beings, without the concourse of the male. With
most of the lower animals and even with mammals, the ova
show a trace of parthenogenetic power, for without being
fertilised they pass through the first stages of segmentation
Nor can pseudova which do not need fertilisation, be dis-

* Paget, ' Lectures on Pathology,' bold, " Ueber Parthenogenesis," ' Sit
1853, p. 158. zung der math. phys. Classe.' Munich,

« Ibid., pp. 152, 164. Nov. 4th, 1871, p. 240. /SeealsoQua-

^ Translated in ' Annais and Mag. trefages, 'Annales des Sc. Nat. Zoolog.,

of Nat. Hist.,' April, 1870, p. 272. 3rd Series, 1850, p. 138.

* BischofF, as quoted by vou Sie-

Chap. XXVII. OF PANGENESIS. 353

tinguisTied from true ova, as was first shown by Sir J.
Lubbock, and is now admitted by Siebold. So, again, the
germ-balls in tlie larvas of Cecidomjda are said by Leuckart ^
to be formed within the ovarium, but they do not require to
be fertilised. It should also be observed that in sexual
generation, the ovules and the male element have equal power
of transmitting every single character possessed b}" either
parent to their offspring. We see this clearly when hybrids
are paired inter se, for the characters of both grandparents
often appear in the progeny, either perfectly or by segments.
It is an error to suppose that the male transmits certain
characters and the female other characters; although no doubt,
from unknown causes, one sex sometimes has a much stronger
power of transmission than the other.

It has, however, been maintained by some authors that a
bud differs essentially from a fertilised germ, in always re-
producing the perfect character of the parent-stock ; whilst
fertilised germs give birth to variable beings. But there is
no such broad distinction as this. In the eleventh chapter
numerous cases were advanced showing that buds occasionally
grow into plants having quite new characters ; and the
varieties thus produced can be propagated for a length of
time by buds, and occasionally by seed. Nevertheless, it must
be admitted that beings produced sexually are much more
liable to vary than those produced asexually ; and of this fact
a partial explanation will hereafter be attempted. The
variability in both cases is determined by the same general
causes, and is governed by the same laws. Hence new
varieties arising from buds cannot be distinguished from
those arising from seed. Although bud-varieties usually
retain their character during successive bud-generations, yet
they occasionally revert, even after a long series of bud-
generations, to their former character. This tendency to
reversion in buds, is one of the most remarkable of the several
points of agreement between the offspring from bud and
seminal reproduction.

But there is one difference between organisms produr-ed

' ' Oq the Asexual Reproduction of 'Annals and M;ig. of Nat. B^st^,
Cecidomyide Larvae,' translated in March, 1866, pp. 167, 171,

354 PROVISIONAL HYPOTHESIS Chap. XXVII

sexually and asexnally, which, is very general. The former
pass in the course of their development from a very low stage
to their highest stage, as we see in the metamorphoses of insects
and of many other animals, and in the concealed metamorphoses
of the vertebrata. ■ Animals propagated asexually by buds
or fission, on the other hand, commence their development at
that stage at which the budding or self-dividing animal may
happen to be, and therefore do not pass through some of the
lower developmental stages.^^ Afterwards, they often advance
in organisation, as we see in the many cases of " alternate
generation." In thus speaking of alternate generation, I
follow those naturalists who look at this process as essentially
one of internal budding or of fissijiarous generation. Some
of the lower plants, however, such as mosses and certain alg{«,
according to Dr. L. Eadlkofer,^^ when propagated asexually, do
undergo a retrogressive metamorphosis. As far as the final
cause is concerned, we can to a certain extent understand why
beings propagated by buds should not pass through all the
early stages of development; for with each organism the
structure acquired at each stage must be adapted to its
peculiar habits ; and if there are places for the support of many
individuals at some one stage, the simplest plan will be that
they should be multiplied at this stage, and not that they
should first retrograde in their development to an earlier or
simpler structure, which might not be fitted for the then
surrounding conditions.

From the several foregoing considerations we may conclude
that the difference between sexual and asexual generation
is not nearly so great as at first appears ; the chief difference
being that an ovule cannot continue to live and to be fully
developed unless it unites with the male element ; but even
this difference is far from invariable, as shown by the many
cases of parthenogenesis. We are therefore naturally led to
inquire what the final cause can be of the necessity in

'° Prof. AUman speaks ('Transact. " of zooids, that no retrogression ever

R. Soc. of Edinburgh,' vol. xxvi., 1870, " talces place in the series."

p. 102) decisively on this head with ^^ 'Annals and Mag. of Nat. Hist.,

respect to the Hydroida : he says, "It 2nd series, vol. xx., 1857, pp. locJ-

" is a universal law in the succession 455

Chap. XXVIL OF PANGENESIS. 355

ordinary generation for the concourse of the two sexual
elements.

Seeds and ova are often highly serviceable as the means of
disseminating plants and animals, and of preserving them
during; one or more seasons in a dormant state : but un-
impregnated seeds or ova, and detached buds, would be equally
serviceable for both purposes. We can, however, indicate
two important advantages gained by the concourse of the
two sexes, or rather of two individuals belonging to opposite
sexes; for, as I have shown in a former chapter, the structure
of every organism appears to be especially adapted for the
concurrence, at least occasionally, of two individuals. When
species are rendered highly variable by changed conditions
of life, the free intercrossing of the varying individuals
tends to keep each form fitted for its proper place in nature ;
and crossing can be effected only by sexual generation ; but
whether the end thus gained is of sufBcient importance to
account for the first origin of sexual intercourse is extremely
doubtful. Secondly, I have shown from a iarge body of
facts, that, as a slight change in the conditions of life is
beneficial to each creature, so, in an analogous manner, is the
change effected in the germ by sexual union with a distinct
individual ; and I have been led, from observing the many
widely-extended provisions throughout nature for this purpose,
and from the greater vigour of crossed organisms of all
kinds, as proved by direct experiments, as well as from the
evil effects of close interbreeding when long continued, to
believe that the advantage thus gained is very great.

Why the germ, which before impregnation undergoes a
certain amount of development, ceases to progress and
perishes, unless it be acted on by the male element; and
why conversely the male element, which in the case of some
insects is enabled to keep alive for four or five years,
and in the case of some plants for several years, likewise
perishes, unless it acts on or unites with the germ, are
questions which cannot be answered with certainty. It is,
however, probable that both sexual elements perish, unless
brought into union, simply from including too little formative
matter for independent development. Quatrefages has shown

356

PROVISIONAL HYPOTHESIS

Chap. XXVII.

in the case of the Teredo/^ as did formerly Prevost and Dumas
with other animals, that more than one spermatozoon is
requisite to fertilise an ovum. This has likewise been shown
by Newport,^^ who proved by numerous experiments, that,
when a very small number of spermatozoa are applied to the
ova of Batrachians, they are only partially impregnated, and
an embryo is never fully develojied. The rate also of the
segmentation of the ovum is determined by the number of the
spermatozoa. With respect to plants, nearly the same results
were obtained by Kolreuter and Gartner. This last careful
observer, after making successive trials on a Malva with
more and more pollen-grains, found,^* that even thirty grains
did not fertilise a single seed ; but when forty grains were
applied to the stigma, a few seeds of small size were formed.
In the case of Mirabilis the pollen grains are extraordinarily
large, and the ovarium contains only a single ovule ; and
these circumstances led Naudin^^ to make the following
experiments : a flower was fertilised by three grains and
succeeded perfectly ; twelve flowers were fertilised by two
grains, and seventeen flowers by a single grain, and of these
one flower alone in each lot perfected its seed : and it deserves
especial notice that the plants produced by these two seeds
never attained their proper dimensions, and bore flowers of
remarkably small size. From these facts we clearly see that
the quantity of the peculiar formative matter which is
contained within the spermatozoa and pollen-grains is an all-
important element in the act of fertilisation, not only for
the full development of the seed, but for the vigour of the
plant produced from such seed. We see something of the
same kind in certain cases of parthenogenesis, that is, when
the male element is wholly excluded ; for M. Jourdan ^^

'- ' Annales des Sc. Nat.,' 3rd series,
1850, torn. xiii.

13 'Transact. Phil. Soc.,' 1851, pp.
196, 208, 210 ; 1853, pp. 245, 247.

^* ' Beitrage zur Kenntniss,' &c.,
1844, s. 345.

** 'Nouvelles Archives du Mu-
B^um,' torn. i. p. 27.

'^ As quoted by Sir J. Lubbock in
'Nat. Hist. Review' 1862, p. 345.

Weijenbergh also raised ('Nature,'
Dec. 21, 1871, p. 149) two successive
generations from unimpregnated fe-
males of another lepidopterous insect,
Liparis dispar. These females did
not produce at most one-twentieth
of their full complement of eggs, and
many of the eggs were worthless.
Moreover the caterpillars raised from
these unfertilised eggs •' possessed far

Chap. XXVII. OF PANGENESIS. 357

found that, out of about 58,000 eggs laid by unimpregnated
silk-moths, luany passed through their early embryonic
stages, showing that they were capable of self-development,
but only twenty-nine out of the whole number produced
caterpillars. The same principle of quantity seems to hold
good even in artificial fissiparous reproduction, for HaeckeP^
found that by cutting the segmented and fertilised ova or
larvEe of Siphonophor* (jelly-fishes) into pieces, the smaller
the pieces were, the slower was the rate of development, and
the larvae thus produced were by so much the more imperfect
and inclined to monstrosity. It seems, therefore, probable
that with the separate sexual elements deficient quantity
of formative matter is the main cause of their not having
the capacity for prolonged existence and development, unless
they combine and thus increase each other's bulk. 'J'he belief
that it is the function of the spermatozoa to communicate
life to the ovule seems a strange one, seeing that the un-
impregnated ovule is already alive and generally undergoes a
certain amount of independent development. Sexual and
asexual reproduction are thus seen not to differ essentially ;
and we have already shown that asexual reproduction, the
power of re-growth and development are all parts of one and
the same great law.

Ee-groivth of amputated parts. — This subject deserves a little
further discussion. A multitude of the lower animals and
some vertebrates possess this wonderful power. For instance,
Spallanzani cut off the legs and tail of the same salamander six
times successively, and Bonnet,^^ did so eight times ; and on
each occasion the limbs were reproduced on the exact line of
amputation, with no part deficient or in excess. An allied
animal, the axolotl, had a limb bitten off, which was re-
produced in an abnormal condition, but when this was

less vitality " than those from ferti- ^® Spallanzani, 'An Essay on Animal

lised eggs. In the third partheno- Reproduction,' translated by Dr.

genetic generation not a single egg Maty, 1769, p. 79. Bonnet, 'GEuvres

yielded a caterpillar. d'Hist. Nat.,' torn, v., part i., 4to,

'' ' Entwickelungsgeschichte der edit., 1781, pp. 343, 350.
Siphonophora,' 1869, p. 73.

858

PROVISIONAL HYPOTHESIS

Chap. XXVII

amputated it was replaced by a perfect liinb.^^ The new
limbs in these cases bud forth, and are developed in the same
manner as during the regular development of a young animal.
For instance, with the Amhlystoma lurida, three toes are first
developed, then the fourth, and on the hind-feet the fifth,
and so it is with a reproduced limb.^°

The power of re-growth is generally much greater during
the youth of an animal or during the earlier stages of its de-
velopment than during maturity. The larvae or tadpoles of the
Batrachians are capable of reproducing lost members, but
not so the adults. ^^ Mature insects have no power of re-
growth, excepting in one order, whilst the larvee of many kinds
have this power. Animals low in the scale are able, as a
general rule, to reproduce lost parts far more easily than those
which are more highly organised. The myriapods offer a good
illustration of this rule ; but there are some strange ex-
ceptions to it — thus Nemerteans, though lowly organised, are
said to exhibit little power of re-growth. With the higher
vertebrata, such as birds and mammals, the power is extremely
limited. ^^

In the case of those animals which may be bisected or
chopped into pieces, and of which every fragment will
reproduce the whole, the power of re-growth must be diffused
throughout the whole body. Nevertheless there seems to be
much truth in the view maintained by Prof. Lessona,^^ that
this capacity is generally a localised and special one, serving
to replace parts which are eminently liable to be lost in each
particular animal. The most striking case in favour of this
view, is that the terrestrial salamander, according to Lessona,
^nnot reproduce lost parts, whilst another species of the

^® Vulpian, as quoted by Prof,
^aivre, ' La Variabilite des Especes,'
i868, p. 112.

20 Dr. P. Hoy, ' The American Natu-
ralist,' Sept. 1871, p. 579.

2^ Dr. Giinther, in Owen's ' Ana-
tomy of Vertebrates,' vol. i., 1866, p.
667. Spallanzani has made similar
observations.

22 A thrush was exhibited before
^he British Association at Hull, in
1853, which had lost its tarsus, and

this member, it was asserted, had
been thrice reproduced ; having been
lost, I presume, each time by disease.
Sir J. Paget informs me that he feels
some doubt about the facts recorded
b}'^ Sir J. Simpson (' Monthly Journal
of Medical Science,' Edinburgh, 1848,
new series, vol. ii. p. 890) of the re-
growth of limbs in the womb in the
case of man.

23 ' Atti della Soc. Ital. di Sc. Nat.,'
vol. xi., 1869, p. 493.

Chap. XXVII. OF PANGENESIS. 359

same genus, the aquatic salamander, has extraordinary powers
of re-growth, as we have just seen ; and this animal is
eminently liable to have its limbs, tail, eyes and jaws bitten
off by other tritons.-* Even with the aquatic salamander
the capacity is to a certain extent localised, for when M.
rhilipeaux,^^ extirpated the entire fore limb together with
the scapula, the power of re-growth was completely lost. It
is also a remarkable fact, standing in opposition to a very
general rule, that the young of the aquatic salamander do not
possess the power of repairing their limbs in an equal degree
with the adults ; ^^ but I do not know that they are more
active, or can otherwise better escape the loss of their limbs,
than the adults. The walking-stick insect, Diapheromera
femorata, like other insects of the same order, can reproduce
its legs in the mature state, and these from their great length
must be liable to be lost : but the ca23acity is localised (as in
the case of the salamander), for Dr. Scudder found,^'' that if
the limb was removed within the trochanto-femoral articula-
tion, it was never renewed. When a crab is seized by one of
its legs, this is thrown off at the basal joint, being afterwards
replaced by a new leg ; and it is generally admitted that this
is a special provision for the safety of the animal. Lastly,
with gasteropod molluscs, which are well known to have the
power of reproducing their heads, Lessona shows that they
are very liable to have their heads bitten off by fishes ; the
rest of the body being protected by the shell. Even with
plants we see something of the same kind, for non-deciduous
leaves and young stems have no power of re-growth, these
parts being easily replaced by growth from new buds ; whilst
the bark and subjacent tissues of the trunks of trees have
great power of re-growth, probably on account of their increase
in diameter, and of their liability to injury from being
gnawed by animals.

'* Lessona states that this is so 'n v. p. 294, as (juoted by Prof. Rolleston

the paper just referred to. See also in his remarltable addx-ess to the 30th

'The American Naturalist,' Sept. annual meeting of the British Medical

1871, p. 579. Association.

" *Comptes Reudus,' Oct. 1, 1866, 27 'Proc. Boston Soc. of Nat. Hist.,'

and June, 1867. vol. xii., 1868-69, p. 1.

'6 Bonnet, ' (Euvres Hist. Nat.,' vol.

360 PROVISIONAL HYPOTHESIS Chap. XXVIL

Graft-Jiyhrids. — It is well known from innumerable trials
made in all parts of the world, that buds may be inserted
into a stock, and that the plants thus raised are not affected
in a greater degree than can be accounted for by changed
nutrition. Nor do the seedlings raised from such inserted
buds partake of the character of the stock, though they are
more liable to vary than are seedlings from the same variety
growing on its own roots. A bud, also, may sport into a new
and strongly-marked variety without any other bud on the
same plant being in the least degree affected. We may there-
fore infer, in accordance with the common view, that each
bud is a distinct individual, and that its formative elements
do not spread beyond the parts subsequently developed
from it. Nevertheless, we have seen in the abstract on
graft hybridisation in the eleventh chapter that buds certainly
include formative matter, which can occasionally combine
with that included in the tissues of a distinct variety or
species ; a plant intermediate between the two parent-forms
being thus produced. In the case of the potato we have seen
that the tubers produced from a bud of one kind inserted into
another are intermediate in colour, size, shape and state of
surface ; that the stems, foliage, and even certain constitutional
peculiarities, such as precocity, are likewise intermediate.
With these well-established cases, the evidence that graft-
hybrids have also been produced with the laburnum, orange,
vine, rose, &c., seems sufficient. But we do not know
under what conditions this rare form of reproduction is
possible. From these several cases we learn the important
fact that formative elements capable of blending with those
of a distinct individual (and this is the chief character-
istic of sexual generation), are not confined to the repro-
ductive organs, but are present in the buds and cellular tissue
of plants ; and this is a fact of the highest physiological
importance.

Direct Action of the Male Element on the Female. — In
the eleventh chapter, abundant proofs were given that
foreign pollen occasionally affects in a direct manner the
mother-plant. Thus, when Gallesio fertilised an orange-
flower with pollen from the lemon, the fruit bore stripes

Chap. XXVII. OF PANGENESIS. 361

of perfectly characterised lemon-peel. With peas, several
observers have seen the colour of the seed-coats and even
of the pod directly affected by the pollen of a distinct
variety. So it has been with the fruit of the apple, which
consists of the modified calyx and upper part of the flower-
stalk. In ordinary cases these parts are wholly formed by
the mother-plant. We here see that the formative elements
included within the male element or pollen of one variety
can affect and hybridise, not the part which they are properly
adapted to affect, namely, the ovules, but the partially-developed
tissues of a distinct variety or species. AVe are thus brought
half-way towards a graft-hybrid, in which the formative
elements included within the tissues of one individual com-
bine with those included in the tissues of a distinct variety
or species, thus giving rise to a new and intermediate form,
independently of the male or female sexual organs.

With animals which do not breed until nearly mature, and
of which all the parts are then fully developed, it is hardly
possible that the male element should directly affect the
female. But we have the analogous and perfectly well-ascer-
tained case of the male element affecting (as with the
quagga and Lord Morton's mare) the female or her ova, in
such a manner that when she is impregnated by another
male her offspring are affected and hybridised by the first
male. The explanation would be simple if the spermatozoa
could keep alive within the body of the female during the
long interval which has sometimes elapsed between the two
acts of impregnation ; but no one will suppose that this is
possible with the higher animals.

Development. — The fertilised germ reaches maturity by a
vast number of changes : these are either slight and slowly
effected, as when the child grows into the man, or are great
and sudden, as with the metamorphoses of most insects.
Between these extremes we have every gradation, even within
the same class; thus, as Sir J. Lubbock has shown,^^ there
is an Ephemerous insect which moults above twenty times,
undergoing each time a slight but decided change of structure ;
and these chd,nges, as he further remarl^, probably reveal to

^* 'Transact. Linn. Soxj.,' vol. xxiv,, 1863, p, 62.

362 PROVISIONAL HYPOTHESIS Chap. XXVII

tis the normal stages of development, which are concealed
and hurried through or suppressed in most other insects.
In ordinary metamorphoses, the parts and organs appear to
become changed into the corresponding parts in the next
stage of development ; but there is another form of develop-
ment, which has been called by Professor Owen metagenesis.
In this case " the new parts are not moulded upon the inner
*' surface of the old ones. The plastic force has changed its
" course of operation. The outer case, and all that gave form
" and character to the precedent individual, perish and are
" cast off"; they are not changed into the corresponding parts
" of the new individual. These are due to a new and distinct
" developmental process," &c.^^ Metamorphosis, however,
graduates so insensibly into metagenesis, that the two pro-
cesses cannot be distinctly separated. For instance, in the
last change which Cirripedes undergo, the alimentary canal
and some other organs are moulded on pre-existing parts ;
but the eyes of the old and the young animal are developed
in entirely diiferent parts of the bod}^ ; the tips of the mature
limbs are formed within the larval limbs, and may be said
to be metamorphosed from them ; but their basal portions
and the whole thorax are developed in a plane at right angles
to the larval limbs and thorax ; and this may be called
metagenesis. Ihe metagenetic process is carried to an ex-
treme point in the development of some Echinoderms, for
the animal in the second stage of development is formed
almost like a bud within the animal of the first stage,
the latter being then cast off like an old vestment, yet
sometimes maintaining for a short period an independent
vitality.^"

If, instead of a single individual, several were to be thus
developed metagenetically within a pre-existing form, the
process would be called one of alternate generation. The
young thus developed may either closely resemble the encasing

** 'Parthenogenesis,' 1849, pp. 25, graduates into gemmation or zoid-

26. Prof. Huxley has some excellent formation, which is in fact the same

remarks (' Medical Times,' 1856, p. as metagenesis.

637) on this subject in reference to ^^ Prof. J. Reay Greene, in Giin-

the development of star -fishes, and ther's ' Record of Zoolog. Lit.,' 1865,

shows how curiously metamorphosis p. 625.

1

Chap. XXVII OF PANGENESIS. 363

parent-form, as with the larvae of Cecidoniyia, or may differ
to an astonishing degree, as with many parasitic worms and
jelly-fishes; but this does not make any essential difference
in the process, any more than the greatness or abruptness of
the change in the metamorphoses of insects.

The whole question of development is of great importance
for our present subject. When an organ, the eye, for instance,
is metagenetically formed in a part of the body where during
the previous stage of development no eye existed, we must
look at it as a new and independent growth. The absolute
independence of new and old structures, although corre-
sponding in structure and function, is still more obvious when
several individuals are formed within a previous form, as in
the cases of alternate generation. The same important prin-
ciple probably comes largely into play even in the case of
apparently continuous growth, as we shall see when we con-
sider the inheritance of modifications at corresponding ages.

We are led to the same conclusion, namely, the independ-
ence of parts successively developed, by another and quite
distinct grouj) of facts. It is well known that many animals
belonging to the same order, and therefore not differing widely
from each other, pass through an extremely different course
of development. Thus certain beetles, not in any way re-
markably different from others of the same order, undergo
what has been called a hyper-metamorphosis — that is, they
pass through an early stage wholly different from the ordinary
grub-like larva. In the same sub-order of crabs, namely, the
Macroura, as Fritz Miiller remarks, the river cray-fish is
hatched under the same form which it ever afterwards retains ;
the young lobster has divided legs, like a Mysis ; the Paleemon
appears under the form of a Zoea, and I'eneus under the
Kauplius-form ; and how wonderfully these larval forms differ
from one another, is known to every naturalist.-^^ Some
other crustaceans, as the same author observes, start from the
same point and arrive at nearly the same end, but in the

*' Fritz Miiller's * Fiir Darwin,' Nat.,' 2nd series, Zoolog., torn. iii. p.

1864, s. 65, 71. The highest 322) on the difference in the meta-

authority on crustaceans. Prof. Milne- morphosis of closely-allied genera.
Edwards, insists (' Annal. des Sci.

364 PROVISIONAL HYPOTHESIS Chap. XXVII.

middle of their development are widely different from one
another. Still more striking cases could be given v^ith
respect to the Echinodermata. AYith the Medusae or jelly-
fishes Professor AUman observes, " The classification of the
" Hydroida would be a comparatively simple task if, as has
" been erroneously asserted, generically-identical medusoids
*' always arose from generically-identical pol^^poids ; and, on
" the other hand, that generically-identical polypoids always
" gave origin to generically-identical medusoids." So again.
Dr. Strethill Wright remarks, " In the life-history of the
" Hydroidee any phase, planuloid, polypoid, or medusoid, may
" be absent." ^2

According to the belief now generally accepted by our best
naturalists, all the members of the same order or class, for
instance, the Medusae or the Macrourous crustaceans, are
descended from a common progenitor. During their descent
they have diverged much in structure, but have retained
much in common ; and this has occurred, though they have
passed through and still pass through marvellously different
metamorphoses. This fact well illustrates how independent
each structure is from that which precedes and that which
follows it in the course of development.

TJie Functional Independence of the Elements or Units of tlie
Body. — Physiologists agree that the whole organism consists
of a multitude of elemental parts, which are to a great extent
independent of one another. Each organ, says Claude
Bernard,^^ has its proper^ life, its autonomy ; it can develop
and reproduce itself independently of the adjoining tissues.
A great German authority, Virchow,^* asserts still more
emphatically that each system consists of an " enormous

" mass of minute centres of action Every element has

" its own special action, and even though it derive its stimulus
" to activity from other parts, yet alone effects the actual
" performance of duties Every single epithelial and

'2 Prof. Allraan, in ' Annals and by Sars.
Mag. of Nat. Hist.,' 3rd series, vol. " « Tissus Vivant?,' 1866, p. 22.

xiii., 1864, p. 348; Dr. S. Wright, ^4 < Cellular Pathology,' translat.

ibid., vol. viii., 1861, p. 127. See by Dr. Chance, 1860, pp. 14, 18, 83,

also p. 358 for analogous statements 460.

Chap. XXVII. OF PANGENESIS. 365

*' muscular fibre-cell leads a sort of parasitical existence in

" relation to the rest of the body Every single bone-

*' corpuscle really possesses conditions of nutrition peculiar to
*' itself." Each element, as Sir J. Paget remarks, lives its
appointed time and then dies, and is replaced after being
cast off" or absorbed.^^ I presume that no physiologist doubts
that, for instance, each bone-corpuscle of the finger differs
from the corresponding corpuscle in the corresponding joint
of the toe ; and there can hardly be a doubt that even those
on the corresponding sides of the body differ, though almost
identical in nature. This near approach to identity is
curiously shown in many diseases in which the same exact
points on the right and left sides of the body are similarly
affected ; thus Sir J. Paget ^^ gives a drawing of a diseased
pelvis, in which the bone has grown into a most complicated
pattern, but " there is not one spot or line on one side which
*' is not represented, as exactly as it would be in a mirror, on
" the other."

Many facts support this view of the independent life of
each minute element of the body. Yirchow insists that a
single bone-corpuscle or a single cell in the skin may become
diseased. The spur of a cock, after being inserted into the
ear of an ox, lived for eight years, and acquired a weight of
396 grammes (nearly fourteen ounces), and the astonishing
leng-th of twenty-four centimetres, or about nine inches ; so
that the head of the ox appeared to bear three horns.-^' The
tail of a pig has been grafted into the middle of its back, and
reacquired sensibility. Dr. Oilier ^^ inserted a piece of perios-
teum from the bone of a young dog under the skin of a rabbit,
and true bone was developed. A multitude of similar facts
could be given. 1"he frequent presence of hairs and of per-
fectly developed teeth, even teeth of the second dentition, in
ovarian tumours,^^ are facts leading to the same conclusion.

^^ Paget. ' Surgical Pathology,' des Os,' p. 8.

vol. i., 1853, pp. I'i-U. 39 Isidore GeofTroy Saint-Hilaire,

3® Ibid., p. 19. 'Hist, des Anomalies,* torn. ii. pp.

'' See Prof. Mantegazza's interest- 549, 560, 562 ; Virchow, ibid., p.

ing work, ' Degli iunesti Animali,' &c., 484. Lawson Tait, ' The Pathology of

Milano, 1865, p. 51, tab. 3. Diseases of the Ovaries,' 1874, pp. 61,

" 'De la Production Artificielle 62.

S6Q PROVISIONAL HYPOTHESIS Chap. XXVII

Mr. Lawson Tait refers to a tumour in wliich "over 300
teeth, were found, resembling in many respects milk-teeth. ;"
and to another tumour, " full of hair which had grown and
" been shed from one little spot of skin not bigger than the tip
" of my little finger. The amount of hair in the sac, had it
" grown from a similarly sized area of the scalp, would have
" taken almost a lifetime to grow and be shed."

Whether each of the innumerable autonomous elements of
the body is a cell or the modified product of a cell, is a more
doubtful question, even if so wide a definition be given to the
term, as to include cell-like bodies without walls and without
nuclei. *° The doctrine of omnis cellula e celluld is admitted
for plants, and widely prevails with respect to animals."*^
Thus Virchow, the great supporter of the cellular theory,
whilst allowing that difficulties exist, maintains that every
atom of tissue is derived from cells, and these from pre-
existing cells, and these primarily from the egg, which he
regards as a great cell. That cells, still retaining the same
nature, increase by self-division or proliferation, is admitted
by every one. But when an organism undergoes great
changes of structure during development, the cells, which at
each stage are supposed to be directly derived from previously
existing cells, must likewise be greatly changed in nature ;
this change is attributed by the supporters of the cellular
doctrine to some inherent power which the cells possess,
and not to any external agency. Others maintain that cells
and tissues of all kinds may be formed, independently of pre-
existing cells, from plastic lymph or blastema. Whichever
view may be correct, every one admits that the body consists
of a multitude of organic units, all of which possess their
own proper attributes, and are to a certain extent independent
of all others. Hence it will be convenient to use indifferently
the terms cells or organic units, or simply units.

Variahility and Inheritance. — We have seen in the twenty-
second chapter that variability is not a principle co-ordinate
with life or reproduction, but results from special causes,

*" For the most recent classification *^ Dr. W. Turner, 'The Present

of cells, see Ernst Hackel's ' Geuerelle Aspect of Cellular Pathology,' ' Edin-
Morpholog.,' Baud ii., 1866, s. 275. burgh Medical Journal,' April, 1863.

Chap. XXVII. OF PANGENESIS. 367

generally from changed conditions acting during snccessive
generations. The fluctuating variability thub induced is ap-
parently due in part to the sexual system being easily affected,
so that it is often rendered impotent ; and when not so
seriously affected, it often fails in its proper function of
transmitting truly the characters of the parents to the
offsjDring. But variability is not necessarily connected with
the sexual system, as we see in the cases of bud- variation.
Although we are seldom able to trace the nature of the con-
nection, many deviations of structure no doubt result from
changed conditions acting directly on the organisation, in-
dependently of the reproductive system. In some instances
we may feel sure of this, when all, or nearly all the individuals
which have been similarly exposed are similarly and defi-
nitely affected, of which several instances have been given.
But it is by no means clear why the offspring should be
affected by the exposure of the parents to new conditions,
and why it is necessary in most cases that several generations
should have been thus exposed.

How, again, can we explain the inherited effects of the use
or disuse of particular organs ? The domesticated duck flies
less and walks more than the wild duck, and its limb-bones
have become diminished and increased in a corresponding
manner in comparison with those of the wild duck. A
horse is trained to certain paces, and the colt inherits similar
consensual movements. The domesticated rabbit becomes
tame from close confinement ; the dog, intelligent from
associating with man ; the retriever is taught to fetch and
carry ; and these mental endowments and bodily powers are
all inherited. Nothing in the whole circuit of physiology is
more wonderful. How can the use or disuse of a particular
limb or of the brain affect a small aggregate of reproductive
cells, seated in a distant part of the body, in such a manner
that the being developed from these cells inherits the charac-
ters of either one or both parents ? Even an imperfect answer
to this question Avould be satisfactory.

In the chapters devoted to inheritance it was shown that a
multitude of newly- acquired characters, whether injurious or
beneficial, whether of the lowest or highest vital importance,

36S PROVISIONAL HYPOTHESIS Chap. XXVII.

are often faithfully transmitted — frequently even when one
parent alone possesses some new peculiarity; and we may
on the whole conclude that inheritance is the rule, and
n on -inheritance the anomaly. In some instances a character
is not inherited, from the conditions of life being directly
opposed to its development ; in many instances, from the
conditions incessantly inducing fresh variability, as with
grafted fruit-trees and highly-cultivated flowers. In the re-
maining cases the failure may be attributed to reversion, by
which the child resembles its grandparents or more remote
progenitors, instead of its parents.

Inheritance is governed by various laws. Characters which
first appear at an}^ particular age tend to reappear at a corre-
sponding age. They often become associated with certain
seasons of the year, and reappear in the offspring at a corre-
sponding season. If they appear rather late in life in one sex,
they tend to reappear exclusively in the same sex at the
same period of life.

The principle of reversion, recently alluded to, is one of
the most wonderful of the attributes of Inheritance. It
proves to us that the transmission of a character and its
development, which ordinarily go together and thus escape
discrimination, are distinct powers ; and these jDowers in some
cases are even antagonistic, for each acts altematel}?' in suc-
cessive generations. Reversion is not a rare event, depending
on some unusual or favourable combination of circumstances,
but occurs so regularly with crossed animals and plants, and
so frequently with uncrossed breeds, that it is evidently an
essential part of the principle of inheritance. We know that
changed conditions have the power of evoking long-lost
characters, as in the case of animals becoming feral. The
act of crossing in itself possesses this power in a high degree.
What can be more wonderful than that characters, which
have disappeared during scores, or hundreds, or even thou-
sands of generations, should suddenly reappear perfectly
developed, as in the case of pigeons and fowls, both when
purely bred and especially when crossed ; or as with the
zebrine stripes on dun-coloured horses, and other such cases ?
Many monstrosities come under this same head, as when

Chap. XXVK. OF PANGENESIS. 369

rudimentary organs are redeveloped, or when an organ which
we must believe was possessed by an early progenitor of the
species, but of which not even a rudiment is left, suddenly
reappears, as with the fifth stamen in some Scroj)hulariace8e.
We have already seen that reversion acts in bud-reproduction ;
and we know that it occasionally acts during the growth of
the same individual animal, especially, but not exclusively, if
of crossed parentage, — as in the rare cases described of fowls,
pigeons, cattle, and rabbits, which have reverted to the colours
of one of their parents or ancestors as they advanced in years.
We are led to believe, as formerly explained, that every
character which occasionally reappears is present in a latent
form in each generation, in nearly the same manner as in
male and female animals the secondary characters of the
opposite sex lie latent and ready to be evolved when the
reproductive organs are injured. This comparison of the
secondary sexual characters which lie latent in both sexes,
with other latent characters, is the more appropriate from
the case recorded of a Hen, which assumed some of the
masculine characters, not of her own race, but of an early
progenitor; she thus exhibited at the same time the re-
development of latent characters of both kinds. In every
living creature we may feel assured that a host of long-lost
characters lie ready to be evolved under proper conditions.
How can we make intelligible and connect with other facts,
this wonderful and common capacity of reversion, — this
power of calling back to life long-lost characters ?

Part II.

I have now enumerated the chief facts which every one
would desire to see connected by some intelligible bond. This
can be done, if we make the following assumptions, and
much may be advanced in favour of the chief one. The
secondary assumptions can likewise be supported by various
physiological considerations. It is universally admitted that
the cells or units of the body increase by self-division or
proliferation, retaining the same nature, and that they
ultimately become converted into the various tissues and

370 PROVISIONAL HYPOTHESIS Chap. XXVII.

Bubstances of the body. But besides this means of increase
I assume that the units throw off minute granules which
are dispersed throughout the whole system ; that these, when
supplied with proper nutriment, multiply by self-division,
and are ultimately developed into units like those from which
they were originally derived. These granules may be called
gemmules. They are collected from all parts of the system
to constitute the sexual elements, and their development in
the next generation forms a new being ; but they are like-
wise capable of transmission in a dormant state to future
generations and may then be developed. Their development
depends on their union with other partially developed or
nascent cells which precede them in the regular course of
growth. Why I use the term union, will be seen when we
discuss the direct action of pollen on the tissues of the mother-
plant. G emmules are supposed to be thrown off by every unit,
not only during the adult state, but during each stage of
development of every organism ; but not necessarily during
the continued existence of the same unit. Lastly, I assume
that the gemmules in their dormant state have a mutual
affinity for each other, leading to their aggregation into buds
or into the sexual elements. Hence, it is not the reproduc-
tive organs or buds which generate new organisms, but the
units of which each individual is composed. These assump-
tions constitute the provisional hypothesis wliich I have called
Pangenesis. Views in manj'- respects similar have been pro-
pounded by various authors."*^

42 Mr. G. H. Lewes (' Fortnightly tially different. Bonnet (' (Euvres
Review,* Nov. 1, 1868, p. 506) remarks d'Hist. Nat.,' tom. v., part i., 1781,
on the number of writers who have 4to edit., p. 334) speaks of the limbs
advanced nearly similar views. More having germs adapted for the repara-
than two thousand years ago Aristotle tion of all possible losses ; but
combated a view of this kind, which, whether these germs are supposed to
as I hear from Dr. W. Ogle, was be the same with those within buds
held by Hippocrates and others. Ray, and the sexual organs is not clear,
in his ' Wisdom of God ' (2nd edit.. Prof. Owen says (' Anatomy of Verte-
1692, p. 68), says that "every part brates,' vol. lii., 1868, p. 813) that
" of the body seems to club and con- he fails to see any fundamental differ-
" tribute to the seed." The "organic ence between the views which he pro-
molecules " of Buffon (' Hist. Nat. pounded in his ' Parthenogenesis *
Gen.,' edit, of 1749, tom. ii. pp. 54, 62, (1 849, pp. 5-8), and which he now con-
329, 333, 420, 425) appear at first siders as erroneous, and my hypothesis
sight to be the same as the gemmules of pangenesis : but a reviewer (' .Tour-
of my hypothesis, but they are essen- nal of Anat. and Phys.,' May, 1869,

Chap. XXVII. OF PANGENESIS. 371

Before proceeding to show, firstly, liow far these assump-
tions are in themselves probable, and secondly, how far they
connect and explain the various groups of facts with which
we are concerned, it may be useful to give an illustration, as
simple as possible, of the hypothesis. If one of the Protozoa be
formed, as it appears under the microscope, of a small mass of
homogeneous gelatinous matter, a minute particle or gemmule
thrown off from any part and nourished under favourable
circumstances would reproduce the whole ; but if the upper
and lower surfaces were to differ in texture from each other
and from the central portion, then all three parts would have
to throw off gemmules, which when aggregated by mutual
affinity would form either buds or the sexual elements, and
would ultimately be developed into a similar organism.
Precisely the same view may be extended to one of the
higher animals ; although in this case many thousand
gemmules must be thrown off from the various parts of the
body at each stage of development; these gemmules being
developed in union with pre-existing nascent cells in due
order of succession.

Physiologists maintain, as we have seen, that each unit of
the body, though to a large extent dependent on others, is
likewise to a certain extent independent or autonomous, and
has the power of increasing by self-division. I go one step
further, and assume that each unit casts off free gemmules
which are dispersed throughout the system, and are capable
under proper conditions of being developed into similar units.
Nor can this assumption be considered as gratuitous and
improbable. It is manifest that the sexual elements and buds
include formative matter of some kind, capable of develop-
ment ; and we now know from the production of graft-hybrids
that similar matter is dispersed throughout the tissues of

p. 441) shows how different they Lastly, it appears from a review of

really are. I formerly thought that the present work by Prof. Mante-

the "physiological units " of Herbert gazza (' Xuova Antologia, Mag2;io,'

Spencer (' Principles of Biology,' vol. 1868), that he (in his ' Elementi di

i., chaps, iv. and viii., 1863-64) Igiene,' Ediz. iii., p. 540) clearly

were the same as my gemmules, but foresaw the doctrine of pangenesis.
I now know that this is not the case.

372

PEOVISIONAL HYPOTHESIS

Chap. XXVIL

plants, and can combine with that of another and distinct
plant, giving rise to a new being, intermediate in character.
We know also that the male element can act directly on the
partially developed tissues of the mother-plant, and on the
future progeny of female animals. The formative matter
which is thus dispersed throughout the tissues of plants,
and which is capable of being developed into each unit or
part, must be generated there by some means ; and my chief
assumption is that this matter consists of minute particles
or gemmules cast off from each unit or cell.*^

But I have further to assume that the gemmules in their un-
developed state are capable of largel}'' multiplying themselves
by self -division, like independent organisms. Delpino insists
that to " admit of multiplication by fissiparity in corpuscles,
*' analogous to seeds or buds ... is repugnant to all analogy."
But this seems a strange objection, as Thuret** has seen the
zoospore of an alga divide itself, and each half germinated.
Haeckel divided the segmented ovum of a siphonophora into
many pieces, and these were developed. Nor does the extreme
minuteness of the gemmules, which can hardly diifer much in
nature from the lowest and simplest organisms, render it
improbable that they should grow and multiply. A great
authoritj^. Dr. Beale,'*^ says " that minute yeast cells are
" capable of throwing off buds or gemmules, much less than
" the ToVo'oo ^^ ^^^ ^^^^ ^^ diameter ;" and these he thinks are
" capable of subdivision practically ad infinitum."

A particle of small-pox matter, so minute as to be borne by
the wind, must multiply itself many thousandfold in a person
thus inoculated ; and so with the contagious matter of scarlet
fever.*^ It has recently been ascertained *^ that a minute
portion of the mucous discharge from an animal affected with

** Mr. Lowne has observed (' Jour-
nal of Queckett Microscopical Club,*
Sopt. 23, 1870) certain remarkable
changes in the tissues of the larva of
a fly, which makes him believe " it
** possible that organs and organisms
" are sometimes developed by the
*' aggregation of excessively minute
" gemmules, such as those which Mr.
" Darwin's hypothesis demands."

44

'Annales des Sc. Nat.,' 3rd
series, Bot., tom. xiv., 1850, p. 244.

** ' Disease Germs,' p. 20.

*^ See some very interesting papers
on this subject by Dr. Beale, in
' Medical Times and Gazette,' Sept.
9th, 1865, pp. 273, 330.

*'' Third Report of the R. Comm.
on the Cattle Plague, as quoted in
' Card. Chronicle,' 1866, p. 446.

Chap. XXVU.

OF PANGENESIS.

373

rinderpest, if placed in the blood of a healthy ox, increases
so fast that in a short space of time "the whole mass of
" blood, weighing many pounds, is infected, and every small
" particle of that blood contains enough poison to give,
" within less than forty-eight hours, the disease to another
" animal,"

The retention of free and undeveloped gemmules in the
same body from early youth to old age will appear improb-
able, but we should- remember how long seeds lie dormant in
the earth and buds in the bark of a tree. Their transmission
from generation to generation will appear still more improb-
able ; but here again we should remember that many rudimen-
tary and useless organs have been transmitted during an
indefinite number of generations. We shall presently see
how well the long-continued transmission of undeveLjped
gemmules explains many facts.

As each unit, or group of similar units, throughout the
body, casts off its gemmules, and as all are contained within
the smallest ovule, and wdthin each spermatozoon or pollen-
grain, and as some animals and plants produce an astonishing
number of pollen-grains and ovules,*^ the number and minute-
ness of the gemmules must be something inconceivable. But
considering how minute the molecules are, and how many
go to the formation of the smallest granule of any ordinar;y
substance, this difficulty with respect to the gemmules is not
insuperable. From the data arrived at by Sir W. Thomson,
my son George finds that a cube of i o^^o^o^ of an inch of glass
or water must consist of between 16 million millions, and 131
thousand million million molecules. Ko doubt the molecules
of which an organism is formed are larger, from being more
complex, than those of an inorganic substance, and probably

« Mr. F. Buckland found 6,867,840
eggs in a cod-tish (' Land and Water,'
1868, p. 62). An Ascaris produces
about 64,000,000 eggs (Carpenter's
* Comp. Phys.,' 1854, p. 590). Mr. J.
Scott, of the Royal Botanic Garden
of Edinburgh, calculated, in the same
manner as I have done for some
British Orchids (' Fertilisation of
Orchids,' p. 344), the number of

38

seeds in a capsule of an Acropera
and found the number to be 371,250.
Now this plant produces several
flowers on a raceme, and many ra-
cemes during a season. In an allied
genus, Gongora, Mr. Scott has seen
twenty capsules produced on a single
raceme ; ten such racemes on the
Acropera would yield above seventy-
four millions of seedt

374 PROVISIONAL HYPOTHESIS Chap. XXVII.

many molecules go to the formation of a gemmule ; but when we
bear in mind that a cube of T'ohw^ ^^ ^^ inch is much smaller
than any pollen-grain, ovule or bud, we can see what a vast
number of gemmules one of these bodies might contain.

The gemmules derived from each part or organ must })e
thoroughly dispersed throughout the whole system. We know,
for instance, that even a minute fragment of a leaf of a
Begonia will reproduce the whole plant ; and that if a fresh-
water worm is chopped into small pieces, each will reproduce
the whole animal. Considering also the minuteness of the
gemmules and the permeability of all organic tissues, the
thorough dispersion of the gemmules is not surprising. That
matter may be readily transferred without the aid of vessels
from part to part of the body, we have a good instance in a
case recorded by Sir J. Paget of a lady, whose hair lost its
colour at each successive attack of neuralgia and recovered it
again in the course of a few" days. With plants, however,
and probably with compound animals, such as corals, the
gemmules do not ordinarily spread from bud to bud, but aie
confined to the parts developed from each separate bud ; and
of this fact no explanation can be given.

The assumed elective affinity of each gemmule for that par-
ticular cell which precedes it in due order of development is
supported by many analogies. In all ordinary cases of sexual
reproduction, the male and female elements certainly have a
mutual affinity for each other : thus, it is believed that about
ten thousand species of Compositae exist, and there can be no
doubt that if the pollen of all these species could be simul-
taneously or successively placed on the stigma of any one
species, this one would elect with unerring certainty its own
pollen. This elective capacity is all the more wonderful,
as it must have been acquired since the many species
of this great group of plants branched off from a common
progenitor. On any view of the nature of sexual repro-
duction, the formative matter of each part contained within
the ovules and the male element act on each other by some law
of ^ special affinity, so that corresponding parts affect one
another ; thus, a calf produced from a short-horned cow by a
long-horned bull has its horns affected by the union of the

Chap. XXVII. OF PANGENESIS. 375

two forms, and the offspring from two birds with differently
coloured tails have their tails affected.

The various tissues of the body plainly show, as many phy-
siologists have insisted,*^ an affinity for special organic sub-
stances, whether natural or foreign to the body. "We see this
in the cells of the kidneys attracting urea from the blood ; in
curare affecting certain nerves ; Lytta vesicatoria the kidneys ;
and the poisonous matter of various diseases, as small-pox,
scarlet-fever, hooping-cough, glanders, and hydrophobia,
affecting certain definite parts of the body.

It has also been assumed that the development of each
gemmule depends on its union with another cell or unit
which has just commenced its development, and which pre-
cedes it in due order of growth. That the formative matter
within the pollen of plants, which by our hypothesis consists of
gemmules, can unite with and modify the partially developed
cells of the mother-plant, we have clearly seen in the section
devoted to this subject. As the tissues of plants are formed, as
far as is known, only by the proliferation of pre-existing cells,
we must conclude that the gemmules derived from the
foreign pollen do not become developed into new and separate
cells, but penetrate and modify the nascent cells of the mother-
plant. This process may be compared with what takes place
in the act of ordinary fertilisation, during which the contents
of the pollen-tubes penetrate the closed embryonic sac
within the ovule, and determine the development of the
embryo. According to this view, the cells of the mother-
plant may almost literally be said to be fertilised by the
gemmules derived from the foreign pollen. In this case and
in all others the proper gemmules must combine in due order
with pre-existing nascent cells, owing to their elective affi-
nities. A slight difference in nature between the gemmules
and the nascent cells would be far from interfering with
their mutual union and development, for we well know in
the case of ordinary reproduction that such slight differentia-

*3 Paget, ' Lectures on Pathology,' Tissus Vivants,' pp. 177, 210, 337;

p. 27 ; Virchow, ' Cellular Patho- Miiller's ' Physiology,' Eng. translat.,

logy,' translat. bv Dr. Chance, pp. p. 290.
123, 126, 294- Claude Bernard, 'Des

376 PROVISIONAL HYPOTHEoIS Chap. XXVII.

tion in the sexual elements favours in a marked manner their
union and subsequent development, as well as the vigour of
the offspring thus produced.

Thus far we have been able by the aid of our hypothesis
to throw some obscure light on the problems which have
come before us ; but it must be confessed that many points
remain altogether doubtful. Thus it is useless to specu-
late at what period of development each unit of the body
casts oif its gemmules, as the whole subject of the develop-
ment of the various tissues is as yet far from clear. We
do not know whether the gemmules are merely collected by
some unknown means at certain seasons within the reproduc-
tive organs, or whether after being thus collected they rapidly
multiply there, as the flow of blood to these organs at each
breeding season seems to render probable. Kor do we know
why the gemmules collect to form buds in certain definite
places, leading to the symmetrical growth of trees and corals.
We have no means of deciding whether the ordinary wear
and tear of the tissues is made good by means of gemmules,
or merely by the proliferation of pre-existing cells. If
the gemmules are thus consumed, as seems probable from
the intimate connection between the repair of waste, re-
growth, and development, and more especially from the
periodical changes which many male animals undergo in
colour and structure, then some light would be thrown on
the phenomena of old age, with its lessened power of re-
production and of the repair of injuries, and on the obscure
subject of longevity. The fact of castrated animals, which
do not cast off innumerable gemmules in the act of reproduc-
tion, not being longer-lived than perfect males, seems opposed
to the belief that gemmules are consumed in the ordinary
repair of wasted tissues ; unless indeed the gemmules after
being collected in small numbers within the reproductive
organs are there largely multiplied. ^^

That the same cells or units may live for a long period and

^? Prof. Ray Lankester has dis- parative Longevity in Man and the

cussed several of the points here Lower Animals,' 1870, pp. 36, 77,

referred to as bearing on pangenesis, &c.
in his interesting essay, ' On Com-

Chap. XXVII. OF PANGENESIS. 377

continue multiplying without "being modified hj their union
with free gemmules of an}'' kind, is probable from such cases
as that of the spur of a cock which grew to an enormous size
when grafted into the ear of an ox. How far units are
modified during their normal growth by absorbing peculiar
nutriment from the surrounding tissues, independently of
their union with gemmules of a distinct nature, is another
doubtful point.^^ We shall appreciate this difficulty by
calling to mind what complex yet s^^mmetrical growths the
cells of planfs yield when inoculated by the poison of a
gall-insect. AVith animals various polypoid excrescences and
tumours are generally admitted ^^ to be the direct product,
through proliferation, of normal cells which have become
abnormal. In the regular growth and repair of bones, the
tissues undergo, as Yirchow remarks, ^^ a whole series of
permutations and substitutions. " The cartilage cells may
" be converted by a direct transformation into marrow-cells,
" and continue as such ; or they ma}^ first be converted into
*' osseous and then into medullary tissue ; or lastly, they may
" first be converted into marrow and then into bone. So
" variable are the permutations of these tissues, in themselves
" so nearly allied, and yet in their external appearance so
" completely distinct." But as these tissues thus change
their nature at any age, without any obvious change in their
nutrition, we must suppose in accordance with our hypothesis
that gemmules derived from one kind of tissue combine
with the cells of another kind, and cause the successive
modifications.

We have good reason to believe that several gemmules are
requisite for the development of one and the same unit or
cell; for we cannot otherwise understand the insufficiency
of a single or even of two or three pollen-grains or sper-
matozoa. But we are far from knowing whether the gemmules
of all the units are free and separate from one another, or
whether some are from the first united into small aggregates.

*' Dr. Ross refers to this subject traus. by Dr. Chance, 1860, pp. 00,

in his ' Graft Theory of Disease,' 1«72, 162, 245, 441, 454-.
p. 53. *' Ibid., pp. 412-426.

^* Virchow, 'Cellular Pathology,'

378 PROVISIONAL HYPOIHESIS Chap. XXVII.

A feather, for instance, is a complex structure, and, as each
separate part is liable to inherited variations, I conclude that
each feather generates a large number of gemmules ; but it
is possible that these may be aggregated into a compound
gemmule. The same remark applies to the petals of flowers,
which are sometimes highly complex structures, with each
ridge and hollow contrived for a special purpose, so that
each part must have been separately modified, and the
modifications transmitted; consequently, separate gemmules,
according to our h^'pothesis, must have been thrown oif from
each cell or unit. But, as we sometimes see half an anther
or a small portion of a filament becoming petali-form, or parts
or mere stripes of the calyx assuming the colour and texture
of the corolla, it is probable that with petals the gemmules
of each cell are not aggregated together into a compound
gemmule, but are free and separate. Even in so simple a
case as that of a perfect cell, with its protoplasmic contents,
nucleus, nucleolus, and walls, we do not know whether or
not its development depends on a compound gemmule derived
from each part.^^

Having now endeavoured to show that the several fore-
going assumptions are to a certain extent supported by analo-
gous facts, and having alluded to some of the most doubtful
points, w^e will consider how far the hypothesis brings under
a single point of view the various cases enumerated in the
First Part. All the forms of reproduction graduate into one
another and agree in their product; for it is impossible to
distinguish betw^een organisms produced from buds, from self-
division, or from fertilised germs ; such organisms are liable to
variations of the same nature and to reversions of the same
kind ; and as, according to our hypothesis, all the forms of re-
production depend on the aggregation of gemmules derived
from the whole body, we can understand this remarkable
agreement. Parthenogenesis is no longer wonderful, and if
we did not know that great good followed from the union of
the sexual elements derived from two distinct indi^dduals, the

** See some good eriticisnis on this Lewos in the 'Fortnightly Review,'
head hy Delpino, and by Mr. G. H. Kov. 1, 1868, p. 509.

Chap. XXVII.

OF PANGENESIS.

379

wonder would Le that parthenogenesis did not occur much
oftener than it does. On any ordinary theory of reproduction
the formation of graft-hybrids, and the action of the male
clement on the tissues of the mother-plant, as well as on the
future progeny of female animals, are great anomalies ; but
they are intelligible on our hypothesis. The reproductive
organs do not actually create the sexual elements ; they
merely determine the aggregation and perhaps the multipli-
cation of the gemmules in a special manner. These organs,
however, together with their accessory parts, have high
functions to perform. They adapt one or both elements for
independent temporary existence, and for mutual union. The
Btigmatic secretion acts on the pollen of a plant of the same
species in a wholly different manner to what it does on
the pollen of one belonging to a distinct genus or family.
The spermatophores of the Cephalopoda are wonderfully
complex structures, which were formerly mistaken for para-
sitic worms ; and the spermatozoa of some animals possess
attributes which, if observed in an independent animal, would
be put down to instinct guided by sense-organs, — as when
the spermatozoa of an insect find their way into the minute
microp3^1e of the egg.

The antagonism which has long been observed,^^ with
certain exceptions, between growth and the power of sexual
reproduction ^^ — between the repair of injuries and gemma-
tion— and with plants, between rapid increase by buds,
rhizomes, &c., and the production of seed, is partly explained
by the gemmules not existing in sufficient numbers for these
processes to be carried on simultaneously.

^* Mr. Herbert Spencer (' Princi-
ples of Biology,' vol, ii. p. 430) has
fully discussed this antagonism.

^^ The male salmon is known to
breed at a very early age. The
Triton and Siredon, whilst retaining
their larval branchije, according to
Filippi and Dumeril ('Annals and
Mag. of Nat. Hist.,' 3rd series, 1866,
p. 157), are capable of reproduction.
Ernst Haeckel has recimtly (' Monats-
bericht Akad. Wiss. Berlin,' Feb. 2nd,
1865) observed the surprising case

of a medusa, with its reproductive
organs active, which produces by
budding a widely different form of
medusa ; and this latter also has the
power of sexual reproduction. Krohn
has shown (' Annals and Mag. of
Nat. Hist.,' 3rd series, vol. xix., 1862,
p. 6) that certain other medusse,
whilst sexually mature, propagate
by gemma?. See, also, Kolllker,
' Morphologic und Entwickelungsge-
schichte des Pennatulidenstammes,*
1872, p. 12.

380 PEOVISIOXAL HYPOTHESIS Cm .p. XXVII.

Hardly any fact in plij'siology is more wonderful than the
power of re-growth ; for instance, that a snail should be able
to reproduce its head, or a salamander its eyes, tail, and legs,
exactly at the points where they haA^e been cut off. Such
cases are explained by the presence of gemmules derived from
each part, and disseminated throughout the body. I have
heard the process compared with that of the repair of the
broken angles of a crystal by re-crystallisation ; and the two
processes have this much in common, that in the one case
the polarit}" of the molecules is the efficient cause, and in the
©ther the affinity of the gemmules for particular nascent cells.
But we have here to encounter two objections which apply
not only to the re-growth of a part, or of a bisected individual,
but to fissiparous generation and budding. The first objection
is that the part which is reproduced is in the same stage of
development as that of the being which has been operated on
or bisected; and in the case of buds, that the new beings thus
produced are in the same stage as that of the budding parent.
1'hus a mature salamander, of which the tail has been cut
off, does not reproduce a larval tail ; and a crab does not
reproduce a larval leg. In the case of budding it was
shown in the first part of this chapter that the new being
thus produced does not retrograde in development, — that
is, does not pass through those earlier stages, which the
fertilised germ has to pass through. Kevertheless, the organ-
isms operated on or multipl3dng themselves by buds must,
by our hypothesis, include innumerable gemmules derived
from every part or unit of the earlier stages of development ;
and why do not such gemmules reproduce the amputated
part or the whole body at a corresponding early stage of
development ?

The second objection, which has been insisted on by Delpino,
is that the tissues, for instance, of a mature salamander or crab,
of which a limb has been removed, are already differentiated
and have passed through their whole course of development ;
and how can such tissues in accordance with our hypothesis
attract and combine with the gemmules of the part which is
to be reproduced ? In answer to these two objections we must
bear in mind the evidence which has been advanced, showing

Chap. XXVIL OF PANGENESIS. 'SSI

that at least in a large number of cases the power of re-growth
is a localised faculty, acquired for the sake of repairing special
injuries to which each particular creature is liable ; and in
the case of buds or fissiparous generation, for the sake of
quickly multiplying the organism at a period of life when it
can be supported in large numbers. These considerations
lead us to believe that in all such cases a stock of nascent cells
or of partially developed gemmules are retained for this
special purpose either locally or throughout the body, ready
to combine with the gemmules derived from the cells which
come next in due succession. If this be admitted we have a
sufficient answer to the above two objections. Anyhow, pan-
genesis seems to throw a considerable amount of light on the
wonderful power of re-growth.

It follows, also, from the view just given, that the sexual
elements differ from buds in not including nascent cells or
gemmules in a somewhat advanced stage of development, so
that only the gemmules belonging to the earliest stages are
first developed. As young animals and those which stand
low in the scale generally have a much greater capacity for
re-growth than older and higher animals, it would also appear
that they retain cells in a nascent state, or partially developed
gemmules, more readily than do animals which have already
passed through a long series of developmental changes. 1
may here add that although ovules can be detected in most
or all female animals at an extremely early age, there is no
reason to doubt that gemmules derived from parts modified
during maturity can pass into the ovules.

With respect to hybridism, pangenesis agrees well with
most of the ascertained facts. We must believe, as pre-
viously shown, that several gemmules are requisite for
the development of each cell or unit. But from the occur-
rence of parthenogenesis, more especially from those cases
in which an embryo is only partially formed, we may infer
that the female element generally includes gemmules in nearly
sufficient number for independent development, so that when
united with the male element the gemmules are superabun-
dant. Now, when two species or races are crossed reciprocally,
the offspring do not commonly differ, and this shows that the

882 PROVISIONAL HYPOTHESIS Chap. XXVll.

sexual elements agree in power, in accordance with the view
that both include the same gemmiiles. Hybrids and mongrels
are also generally intermediate in character between the two
parent-forms, yet occasionally they closely resemble one
parent in one part and the other parent in another part, or
even in their whole structure : nor is this difficult to under-
stand on the admission that the gemmules in the fertilised
germ are superabundant in number, and that those derived
from one parent may have some advantage in number,
affinity, or vigour over those derived from the other parent.
Crossed forms sometimes exhibit the colour or other characters
of either parent in stripes or blotches ; and this occurs in
the first generation, or through reversion in succeeding bud
and seminal generations, of which fact several instances were
given in the eleventh chapter. In these cases we must
follow Naudin,^'' and admit that the " essence" or "element"
of the two species, — terms which I should translate into the
gemmules, — have an affinity for their own kind, and thus
separate themselves into distinct stripes or blotches ; and
reasons were given, M^hen discussing in the fifteenth chapter
the incompatibility of certain characters to unite, for believing
in such mutual affinity. When two forms are crossed, one
is not rarely found to be prepotent in the transmission of
its characters over the other; and this we can explain by
again assuming that the one form has some advantage over
the other in the number, vigour, or affinity of its gemmules.
In some cases, however, certain characters are present in the
one form and latent in the other ; for instance, there is a
latent tendency in all pigeons to become blue, and, when a
blue pigeon is crossed with one of any other colour, the blue
tint is generally prepotent. The explanation of this form of
prepotency will be obvious when we come to the considera-
tion of Eeversion.

"When two distinct species are crossed, it is notorious that
they do not jdeld the full or proper number of offspring ;
and we can only say on this head that, as the development
of each organism depends on such nicely-balanced affinities

-' See his excellent discussion on this subject in ' Noiivelles Archives du
Museum,' torn, i, p. 151.

Chap. XXVII. OF PANGENESIS. 383

between a host of gemmules and nascent cells, We need not
feel at all surprised that the commixture of gemmules derived
from two distinct species should lead to partial or complete
failure of development. With respect to the sterility of
hybrids produced from the union of two distinct species, it
was shown in the nineteenth chapter that this depends ex-
clusively on the reproductive organs being specially affected ;
but why these organs should be thus affected we do not
know, any more than why unnatural conditions of life,
though compatible with health, should cause sterility; or
why continued close interbreeding, or the illegitimate unions
of heterostyled plants, induce the same result. The con-
clusion that the reproductive organs alone are affected, and
not the whole organisation, agrees perfectly with the un-
impaired or even increased capacity in hybrid plants for
propagation by buds ; for this implies, according to our
hypothesis, that the cells of the hybrids throw off hybridised
gemmules, which become aggregated into buds, but fail to
become aggregated within the reproductive organs, so as
to form the sexual elements. In a similar manner many
plants, when placed under unnatural conditions, fail to
produce seed, but can readily be propagated by buds. We
shall presently see that pangenesis agrees well with the
strong tendency to reversion exhibited by all crossed animals
and plants.

Each organism reaches maturity through a longer or
shorter course of growth and development : the former term
being confined to mere increase of size, and development
to changed structure. The changes may be small and
insensibly slow, as when a child grows into a man, or many,
abrupt, and slight, as in the metamorphoses of certain
ephemerous insects, or, again, few and strongly-marked, as
with most other insects. Each newly formed part may be
moulded within a previously existing and corresponding
part, and in this case it will appear, falsely as I believe, to
be developed from the old part ; or it may be formed within
a distinct part of the body, as in the extreme cases of
metagenesis. An eye, for instance, may be developed at a
spot where no eye previously existed. We have also seen

384 PROVISIONAL HYPOTHESIS Chap. XXVII.

that allied organic beings in the course of their metamorphoses
sometimes attain nearly the same structure after passing
through widely different forms ; or conversely, after passing
through nearly the same early forms, arrive at widely different
mature forms. In these cases it is very difficult to accept
the common view that the first-formed cells or units possess
the inherent power, independently of any external agency, of
producing new structures wholly different in form, position,
and function. But all these cases become plain on the
hypothesis of pangenesis. The units, during each stage of
development, throw off gemmules, which, multiplying, are
transmitted to the offspring. In the offspring, as soon as
any particular cell or unit becomes partially developed, it
unites with (or, to speak metaphorically, is fertilised by) the
gemmule of the next succeeding cell, and so onwards. But
organisms have often been subjected to changed conditions
of life at a certain stage of their development, and in
consequence have been slightly modified ; and the gemmules
cast off from such modified parts will tend to reproduce parts
modified in the same manner. This process may be repeated
until the structure of the part becomes greatly changed at
one particular stage of development, but this will not ne-
cessarily affect other parts, whether previously or subsequently
formed. In this manner we can understand the remarkable
independence of structure in the successive metamorphoses,
and especially in the successive metageneses of many animals.
In the case, however, of diseases which supervene during old
age, subsequently to the ordinary period of procreation, and
which, nevertheless, are sometimes inherited, as occurs with
brain and heart complaints, we must suppose that the organs
were affected at an early age and threw off at this period
affected gemmules ; but that the affection became visible or
injurious only after the prolonged growth, in the strict sense
of the word, of the part. In all the changes of structure
which regularly supervene during old age, we probably see
the effects of deteriorated growth, and not of true develop-
ment.

The principle of the independent formation of each part,
owing to the union of the proper gemmules with certain

Chap. XXVII. OF PANGENESIS. 385

nascent cells, together with the superauiindance of the gem-
mules derived from both parents, and the subsequent self-
multiplication of the gemmules, throws light on a widely
different group of facts, which on any ordinary view of
development appears very strange. I allude to organs which
are abnormally transposed or multiplied. For instance, a
curious case has been recorded by Dr. Elliott Coues^^ of a
monstrous chicken with a perfect additional riglit leg articu-
lated to the left side of the pelvis. Gold-fish often have
supernumerary fins placed on various parts of their bodies.
"When the "tail of a lizard is broken off, a double tail is some-
times reproduced ; and when the foot of the salamander
was divided longitudinally by Bonnet, additional digits
were occasionally formed. Valentin injured the caudal
gxtremity of an embryo, and three days afterwards it
produced rudiments of a double pelvis and of double hind-
limbs.^^ AVhen frogs, toads, &c., are born with their limbs
doubled, as sometimes happens, the doubling, as Gervais
remarks,*^" cannot be due to the complete fusion of two
embrj^os, with the exception of the limbs, for the larvi^e are
limbless. The same argument is applicable ^^ to certain
insects produced with multiple legs or antennae, for these are
metamorphosed from apodal or antennee-less larvae. Alphonse
Milne-Edwards ^^ has described the curious case of a crusta-
cean in which one eye-peduncle supported, instead of a com-
plete eye, only an imperfect cornea, and out of the centre of
this a portion of an antenna was developed. A case has been
recorded '°^ of a man who had during both dentitions a double
tooth in place of the left second incisor, and he inherited this
peculiarity from his paternal grandfather. Several cases are
known ^* of additional teeth having been developed in the
orbit of the eye, and, more especially with horses, in the palate.

58 *Proc. Boston Soc. of Nat. Hist.,' de I'Homme,' &c., 1862, p. 129.
republished in ' Scientific Opinion,' ^- Gtinther's ' Zoological Record,

Nov. 10, 1869, p. 488. 1864, p. 279.

58 Todd's 'Cyclop, of Anat. and ^"^ Sedgwick, in *Meiico-Chirurg.

Pliys.,' vol. iv., 1849-52, p. 975. Revie\v,''April, 1863, p. 454.

«" 'CompteRendus,'Nov. 14, 1865, ^4 igid. Geoffrey Saiut-Hilaire,

p. 800. 'Hist, des Anomalies,' tom. i., 1832,

®' As previously remarked by pp. 435, 657 ; and tom. ii. p. 560
Quatrefages, in his ' Metamorphoses

38G PROVISIONAL HYPOTHESIS Cuap. XXVIL

Hairs occasionally appear in strange situations, as " within
tlie substance of the brain." ^^ Certain breeds of sheep bear
a whole crowd of horns on their foreheads. As many as five
spurs have been seen on both legs of certain Game-fowls. In
the Polish fowl the male is ornamented with a topknot of
hackles like those on his neck, whilst the female has a top-
knot formed of common feathers. In feather-footed pigeons
and fowls, feathers like those on the wing arise from the
outer side of the legs and toes. Even the elemental parts of
the same feather may be transposed ; for in the Sebastopol
goose, barbules are developed on the divided filaments of the
shaft. Imperfect nails sometimes appear on the stumps of
the amputated fingers of man ; ^® and it is an interesting fact
that with the snake -like Saurians, which present a series
with more and more imperfect limbs, the terminations of tl^
phalanges first disappear, " the nails becoming transferred to
" their proximal remnants, or even to parts which are not
" phalanges." ®^

Analogous cases are of such frequent occurrence with plants
that they do not strike us with sufficient surprise. Super-
numerary petals, stamens, and pistils, are often produced. I
have seen a leaflet low down in the compound leaf of Vicia
saliva replaced by a tendril ; and a tendril possesses many
peculiar properties, such as spontaneous movement and irrita-
bility. The cal3^x sometimes assumes, either wholly or by
stripes, the colour and texture of the corolla. Stamens are so
frequently converted into petals, more or less completely, that
such cases are passed over as not deserving notice ; but as
petals have special functions to perform, namely, to protect
the included organs, to attract insects, and in not a few cases
to guide their entrance by well-adapted contrivances, we can
hardly account for the conversion of stamens into petals merely
by unnatural or superfluous nourishment. Again, the edge of
a petal may occasionally be found including one of the
highest products of the plant, namely, pollen ; for instance,

«^ Vircbow, 'Cellular Pathology,' tome.

1860, p. 66. *^ I>r. Flirbringer, 'Die Knochen

^^ ' Miiller's Phys.,' Eng. Translat., etc. bei den schlangenahnlichen

vol. i., 1833, p. 407. A case of this Sauriern,' as reviewed in 'Journal oi

kind has lately been communicated Anat. and Phys.,' May, 1870, p, 286.

Chap. XXVII. OF PANGENESIS. 387

I have seen the pollen-mass of an Ophrys, which is a very
complex structure, developed in the edge of an upper
petal. The segments of the calyx of the common pea have
been observed partially converted into carpels, including
ovules, and with their tips converted into stigmas. Mr.
Salter and Dr. Maxwell Masters have found pollen within
the ovules of the passion-flower and of the rose. Buds may
be developed in the most unnatural positions, as on the petal
of a flower. Kumerous analogous facts could be given.^^

I do not know how physiologists look at such facts as the
foregoing. According to the doctrine of pangenesis, the
gemmules of the transposed organs become developed in the
wrong place, from uniting with wrong cells or aggregates of
cells during their nascent state ; and this would follow from
a slight modification in their elective affinities. Nor ought
we to feel much surprise at the affinities of cells and gem-
mules varjang, when we remember the many curious cases
given in the seventeenth chapter, of plants which absolutely
refuse to be fertilised by their own pollen, though abun-
dantly fertile with that of an}^ other individual of the
same species, and in some cases only with that of a distinct
species. It is manifest that the sexual elective affinities
of such plants — to use the term employed by Gartner — have
been modified. As the cells of adjoining or homologous
parts will have nearly the same nature, they will be j)articu-
larly liable to acquire by variation each other's elective
affinities ; and we can .thus understand to a certain extent
such cases as a crowd of horns on the heads of certain sheep,
of several spurs on the legs of fowls, hackle-like feathers on the
heads of the males of other fowls, and with the pigeon wing-
like feathers on their legs and membrane between their toes,
for the leg is the homologue of the wing. As all the organs
of plants are homologous and spring from a common axis, it
is natural that they should be eminently liable to transposi-
tion. It ought to be observed that when any compound part,

^* Moquin - Tandon, * Te'ratologie Masters in ' Science Review,' Oct.

Veg.,' 1841, pp. 218, 220, .353. For 1873, p. 369. The Rev. J. M.

the case of the pea, see 'Gardener's Berkeley describes a bud developed

Chron.,' 1866, p. 897. With respect on a petal of a Clarkia, in ' Gard

to pollen within ovules, see Dr. Chronicle,' April 28, 1866.

388 PROVISIONAL HYPOTHESIS Chap. XXVII.

Bucli as an additional limb or an antenna, springs from a false
position, it is only necessary that the few first gemmules
should be wrongly attached ; for these whilst developing
would attract other gemmnles in due succession, as in the
re-growth of an amputated limb. When parts which are
homologous and similar in structure, as the vertebrae of
snakes or the stamens of polj'^androus flowers, &c., are re-
peated many times in the same organism, closely allied
gemmules must be extremely numerous, as well as the points
to which they ought to become united ; and, in accordance
with the foregoing views, we can to a certain extent under-
stand Isid. Geoffrey Saint-Hilaire's law, that parts, which are
already multiple, are extremely liable to vary in number.

Variability often depends, as I have attempted to show,
on the reproductive organs being injuriously affected by
changed conditions ; and in this case the gemmules derived
from the various parts of the body are probably aggregated
in an irregular manner, some superfluous and others deficient.
Whether a superabundance of gemmules would lead to the
increased size of any part cannot be told ; but we can see
that their partial deficiency, without necessarily leading to
the entire abortion of the part, might cause considerable
modifications ; for in the same manner as plants, if their own
pollen be excluded, are easil}^ hybridised, so, in the case of
cells, if the properly succeeding gemmules were absent,
they would probably combine easily, with other and allied
gemmules, as we have just seen with transposed parts.

In variations caused by the direct action of changed con-
ditions, of which several instances have been given, certain
parts of the body are directly affected by the new conditions,
and consequently throw off modified gemmules, which are
transmitted to the offspring. On any ordinary view it is
unintelligible how changed conditions, whether acting on the
embryo, the young or the adult, can cause inherited modifica-
tions. It is equally or even more unintelligible on any
ordinary view, how the effects of the long-continued use or
disuse of a part, or of changed habits of body or mind, can be
inherited. A more perplexing problem can hardly be pro-

Chap. XXVIl. OF PANGENESIS. 389

posed ; but on our view we have only to suppose that certain
cells become at last structurally modified ; and that these
throw off similarly modified gemmiiles. This may occur
at any period of development, and the modification will be
inherited at a corresponding period ; for the modified gem-
mules will unite in all ordinary cases with the proper pre-
ceding cells, and will consequently be developed at the
same period at which the modification first arose. With
respect to mental habits or instincts, we are so profoundly
ignorant of the relation between the brain and the power of
thought that we do not know positively whether a fixed habit
induces any change in the nervous sj^stem, though this seems
highly probable ; but when such habit or other mental at-
tribute, or insanity, is inherited, we must believe that some
actual modification is transmitted ;^^ and this implies, accord-
ing to our hj^pothesis, that gemmules derived from modified
nerve-cells are transmitted to the offspring.

It is generally necessary that an organism should be ex-
posed during several generations to changed conditions or
habits, in order that any modification thus acquired should
appear in the offspring. This may be partly due to the
changes not being at first marked enough to catch attention,
but this explanation is insufficient ; and I can account for the
fact only by the assumption, which we shall see under the
head of reversion is strongly supported, that gemmules derived
from each unmodified unit or part are transmitted in large
numbers to successive generations, and that the gemmules
derived from the same unit after it has been modified go on
multiplying under the same favourable conditions which first
caused the modification, until at last they become sufficiently
numerous to overpower and supplant the old gemmules.

A difficulty may be here noticed ; we have seen that there
is an important difference in the frequency, though not in
the nature, of the variations in plants propagated by sexual
and asexual generation. As far as variability depends on
the imperfect action of the reproductive organs under changed
conditions, we can at once see why plants propagated asexually

^^ See some remarks to this effect by Sir H. Holland in his ' MedicaJ
Kotes.' 1839, p. 32.

390 PROVISIONAL HYPOTHESIS Chap. XXVIL

BhoTild be far less variable than those propagated sexually.
With respect to the direct action of changed conditions, we
know that organisms produced from buds do not pass through
the earlier phases of development; they will therefore not
be exposed, at that period of life when structure is most
readily modified, to the various causes inducing variability
in the same manner as are embryos and young larval forms ;
but whether this is a sufficient explanation I know not.

With respect to variations due to reversion, there is a
similar difference between plants propagated from buds and
seeds. Many varieties can be propagated securely by buds,
but generally or invariably revert to their parent-forms by
seed. So, also, hybridised plants can be multiplied to any
extent by buds, but are continually liable to reversion by
seed, — that is, to the loss of their hybrid or intermediate cha-
racter. I can offer no satisfactory explanation of these facts.
Plants with variegated leaves, j^hloxes with striped flowers,
barberries with seedless fruit, can all be securely propagated
by buds taken from the stem or branches ; but buds from the
roots of these plants almost invariably lose their character
and revert to their former condition. This latter fact is also
inexplicable, unless buds developed from the roots are as
distinct from those on the stem, as is one bud on the stem
from another, and we know that these latter behave like
independent organisms.

Finally, we see that on the hypothesis of pangenesis varia-
bility depends on at least two distinct groups of causes.
Firstly, the deficiency, superabundance, and transposition of
gemmules, and the redevelopment of those which have long
been dormant ; the gemmules themselves not having under-
gone any modification ; and such changes will amply account
for much fluctuating variability. Secondly, the direct action
of changed conditions on the organisation, and of the increased
use or disuse of parts ; and in this case the gemmules from
the modified units will be themselves modified, and, when
sufficiently multiplied, will supplant the old gemmules and
be developed into new structures.

Turning now to the laws of Inheritance. If we suppose a

Chap. XXVII. OF PANGENESIS. 391

homogeneous gelatinous protozoon to vary and assume a
reddish colour, a minute separated particle would naturally,
as it grew to full size, retain the same colour ; and we should
have the simplest form of inheritance."" Precisely the same
view may be extended to the infinitely numerous and diversi-
fied units of which the whole body of one of the higher
animals is composed; the separated particles being our
gemmules. We have already sufficiently discussed by impli-
cation, the important principle of inheritance at corresponding
ages. Inheritance as limited by sex and by the season of the
year (for instance with animals becoming white in winter) is
intelligible if we may believe that the elective affinities of the
units of the body are slightly different in the two sexes,
especially at maturity, and in one or both sexes at different
seasons, so that they unite with difierent gemmules. It
should be remembered that, in the discussion on the abnormal
transposition of organs, we have seen reason to believe that
such elective affinities are readily modified. But I shall soon
have to recur to sexual and seasonal inheritance. These
several laws are therefore explicable to a large extent
through pangenesis, and on no other hypothesis which has as
yet been advanced.

But it appears at first sight a fatal objection to our hj^po-
thesis that a part or organ may be removed during several
successive generations, and if the operation be not followed
by disease, the lost part reappears in the offspring. Dogs and
horses formerly had their tails docked during many genera-
tions without any inherited effect ; although, as we have seen,
there is some reason to believe that the tailless condition of
certain sheep-dogs is due to such inheritance. Circumcision
has been practised by the Jews from a remote period, and in
most cases the effects of the operation are not visible in the
offspring ; though some maintain that an inherited effect does
occasionally appear. If inheritance depends on the presence of
disseminated gemmules derived from all the units of the body,

'" This is the view taken by Prof. elterliohen und im kindlichen Orga-

Haeckel, in his ' Generelle Morpho- nisuius, die Theilung dieser Materie

lof ie ' (B. ii. s. 171), who says: bei der Fortpflanzuug, ist die Ursache

"Lediglich die partielle Idcutitat der der Erbliclikeit."
specitisch constituirten Materie im

392 PROVISIONAL HYPOTHESIS Chap. XXVII.

why does not the amputation or mutilation of a part, especially
if effected on both sexes, invariably affect the offspring ? The
answer in accordance with our hypothesis probably is that
gemmules multiply and are transmitted during a long series
of generations — as we see in the reappearance of zebrine
stripes on the horse — in the reappearance of muscles and other
structures in man which are proper to his lowly organised
progenitors, and in many other such cases. Therefore the
long-continued inheritance of a part which has been removed
during many generations is no real anomaly, for gemmules
formerly derived from the part are multiplied and transmitted
from generation to generation.

We have as yet spoken only of the removal of parts, when
not followed by morbid action : but when the operation is
thus followed, it is certain that the deficiency is sometimes
inherited. In a former chapter instances were given, as of a
cow, the loss of whose horn was followed by suppuration, and
her calves were destitute of a horn on the same side of their
heads. But the evidence which admits of no doubt is that
given by Brown-Sequard with respect to guinea-pigs, which
after their sciatic nerves had been divided, gnawed off their
own gangrenous toes, and the toes of their offspring were de-
ficient in at least thirteen instances on the corresponding feet.
The inheritance of the lost part in several of these cases is all
the more remarkable as only one parent was affected ; but we
know that a congenital deficiency is often transmitted from
one parent alone — for instance, the offspring of hornless cattle
of either sex, when crossed w^ith perfect animals, are often
hornless. How, then, in accordance with our hypothesis can we
account for mutilations being sometimes strongly inherited, if
they are followed by diseased action ? The answer probably
is that all the gemmules of the mutilated or amputated part
are gradually attracted to the diseased surface during the
reparative process, and are there destroyed by the morbid
action.

A few words must be added on the complete abortion of
organs. When a part becomes diminished by disuse pro-
longed during many generations, the principle of economy of
growth, together with intercrossing, will tend to reduce it

Chap. XXVIL OF PANGENESIS. 393

still further as previously explained, but this will not account
for the complete or almost complete obliteration of, for
instance, a minute papilla of cellular tissue representing a
pistil, or of a microscoj)ically minute nodule of bone repre-
senting a tooth. In certain cases of suppression not yet
completed, in which a rudiment occasionally reappears
through reversion, dispersed gemmules derived from this part
must, according to our view, still exist ; we must therefore
suppose that the cells, in union with which the rudiment was
formerly developed, fail in their affinity for such gemmules,
except in the occasional cases of reversion. But when the
abortion is complete and final, the gemmules themselves no
doubt perish ; nor is this in any way improbable, for, though
a vast number of active and long-dormant gemmules are
nourished in each living creature, yet there must be some
limit to their number ; and it appears natural that gemmules
derived from reduced and useless parts would be more liable
to perish than those freshly derived from other parts which
are still in full functional activity.

The last subject that need be discussed, namely, Reversion,
rests on the princij)le that transmission and development,
though generally acting in conjunction, are distinct powers ;
and the transmission of gemmules with their subsequent
development shows us how this is possible. We plainly see
the distinction in the many cases in which a grandfather
transmits to his grandson, through his daughter, characters
which she does not, or cannot, possess. But before proceeding,
it will be advisable to say a few words about latent or
dormant characters. Most, or perhaps all, of the secondary
characters, which appertain to one sex, lie dormant in the
other sex ; that is, gemmules capable of development into the
secondary male sexual characters are included within the
female ; and conversely female characters in the male : we
have evidence of this in certain masculine characters, both
corporeal and mental, appearing in the female, when her
ovaria are diseased or when they fail to act from old age. In
like manner female characters appear in castrated males, as
in the shape of the horns of the ox, and in the absence of
horns in castrated stags. Even a slight change in the

394 PROVISIONAL HYPOTHESIS Chap. XXVII.

conditions of life due to confinement sometimes suffices to pre-
vent the development of masculine characters in male animals,
although their reproductive organs are not permanently
injured. In the many cases in M^hich masculine characters
are periodically renewed, these are latent at other seasons ;
inheritance as limited by sex and season being here com-
bined. Again, masculine characters generally lie dormant in
male animals until they arrive at the proper age for repro-
duction. The curious case formerly given of a Hen which
assumed the masculine characters, not of her own breed
but of a remote progenitor, illustrates the close connection
between latent sexual characters and ordinary reversion.

With those animals and plants which habitually produce
several forms, as with certain butterflies described by Mr.
Wallace, in which three female forms and one male form
co-exist, or, as with the trimorphic species of Lythrum and
Oxalis, gemmules capable of reproducing these different forms
must be latent in each individual.

Insects are occasionally produced vrith one side or one
quarter of their bodies like that of the male, with the other
half or three-quarters like that of the female. In such cases
the two sides are sometimes wonderfully different in structure,
and are separated from each other by a sharp line. As gem-
mules derived from every part are present in each individual
of both sexes, it must be the elective affinities of the nascent
cells which in these cases differ abnormally on the two sides
of the body. Almost the same principle comes into play
with those animals, for instance, certain gasteropods and
Verruca amongst cirripedes, which normally have the two
sides of the body constructed on a very different plan ; and
yet a nearly equal number of individuals have either side
modified in the same remarkable manner.

Reversion, in the ordinary sense of the word, acts so inces-
santly, that it evidently forms an essential part of the
general law of inheritance. It occurs with beings, how^ever
propagated, whether by buds or seminal generation, and
sometimes may be observed with advancing age even in the
same individual. The tendency to reversion is often induced
by a change of conditions, and in the plainest manner b;y

Chap. XXVIL OF PANGENESIS. 395

crossing. Crossed forms of the first generation are generally
nearly intermediate in character between their two parents ;
but in. the next generation the offspring commonly revert to
one or both of their grandparents, and occasionally to more
remote ancestors. How can we account for these facts ?
Each unit in a hybrid must throw off, according to the
doctrine of 23angenesis, an abundance of hybridised gemmules,
for crossed plants can be readily and largely propagated
by buds ; but by the same hypothesis dormant gemmules
derived from both pure parent-forms are likewise present ;
and as these gemmules retain their normal condition, they
would, it is probable, be enabled to multiply largely during
the lifetime of each hybrid. Consequently the sexual elements
of a hybrid will include both pure and hybridised gemmules ;
and when two h^^brids pair, the combination of pure gem-
mules derived from the one hybrid with the pure gemmules
of the same parts derived from the other, would necessarily
lead to complete reversion of character ; and it is, perhajjs,
not too bold a supposition that unmodified and undeteriorated
gemmules of the same nature would be especially apt to
combine. Pure gemmules in combination with hybridised
gemmules would lead to partial reversion. And lastly,
hybridised gemmules derived from both parent-hybrids
would simply reproduce the original hybrid form.'^ All
these cases and degrees of reversion incessantly occur.

It was shown in the fifteenth chapter that certain characters
are antagonistic to each other or do not readily blend ; hence,
when two animals with antagonistic characters are crossed,
it might well happen that a sufficiency of gemmules in the male
alone for the reproduction of his peculiar characters, and in the
female alone for the reproduction of her peculiar characters,
would not be present ; and in this case dormant gemmules
derived from the same part in some remote progenitor might
easily gain the ascendancy, and cause the reappearance of
the long-lost character. For instance, when black and white
pigeons, or black and white fowls, are crossed, — colours which

^* In these remarks I, in fact, species which are crossed. See his
follow Naudin, who speaks of the excellent memoir in the ' Nouvelles
elements or essences of the two Archives dii Museum,' torn. i. p. Jpl.

396 PROVISIONAL HYPOTUKSLS CiiAr. XXVII.

do not readily blend, — blue plumage in the one case, evidently-
derived from the rock-pigeon, and red plumage in the other
case, derived from the wild jungle-cock, occasionally reappear.
With uncrossed breeds the same result follows, under condi-
tions which favour the multiplication and development of
certain dormant gemmules, as when animals become feral
and revert to their pristine character. A certain number of
gemmules being requisite for the development of each cha-
racter, as is known to be the case from several spermatozoa
or pollen-grains being necessary for fertilisation, and time
favouring their multiplication, will perhaps account for the
curious cases, insisted on by Mr. Sedgwick, of certain diseases
which regularly appear in alternate generations. This like-
wise holds good, more or less strictly, with other weakly
inherited modifications. Hence, as I have heard it remarked,
certain diseases appear to gain strength by the intermission
of a generation. The transmission of dormant gemmules
during many successive generations is hardly in itself more
improbable, as previously remarked, than the retention
during many ages of rudimentary organs, or even only of a
tendency to the production of a rudiment ; but there is no
reason to suppose that dormant gemmules can be transmitted
and propagated for ever. Excessively minute and numerous
as they are believed to be, an infinite number derived, during
a long course of modification and descent, from each unit of
each progenitor, could not be supported or nourished by the
organism. But it does not seem improbable that certain
gemmules, under favourable conditions, should be retained
and go on multiplying for a much longer period than
others. Finally, on the view here given, we certainly gain
some insight into the wonderful fact that the child may
depart from the type of both its parents, and resemble its
grandparents, or ancestors removed by many hundreds of
generations.

Conclusion.

The hypothesis of Pangenesis, as applied to the several
great classes of facts just discussed, no doubt is extremely
complex, but so are the facts. The chief assumption is thafc

Chap. XXVII. OF PANGENESIS. 397

all the units of the body, besides having the universally ad-
mitted power of growing by self-division, throw off minute
gemmules which are dispersed through the system. Nor can
this assumption be considered as too bold, for we know from
the cases of graft -hybridisation that formative matter of some
Icind is present in the tissues of plants, which is capable of
combining with that included in another individual, and of
reproducing ever}^ unit of the whole organism. But we have
further to assume that the gemmules grow, multiply, and
ao-o-reo-ate themselves into buds and the sexual elements :
their development depending on their union with other
nascent cells or units. They are also believed to be capable
of transmission in a dormant state, like seeds in the ground,
to successive generations.

In a highly-organised animal, the gemmules throAvn off
from each different unit throughout the body must be incon-
ceivably numerous and minute. Each unit of each part, as
it changes during development, and we know that some
insects undergo at least twenty metamorphoses, must throw
off its gemmules. But the same cells may long continue
to increase by self-division, and even become modified by
absorbing peculiar nutriment, without necessarily throwing
off modified gemmules. All organic beings, moreover, include
many dormant gemmules derived from their grandparents
and more remote progenitors, but not from all their pro-
genitors. These almost infinitely numerous and minute
gemmules are contained within each bud, ovule, sperma-
tozoon, and pollen-grain. Such an admission will be de-
clared impossible; but number and size are only relative
difBculties. Independent organisms exist which are barely
\isible under the highest powers of the microscope, and their
germs must be excessively minute. Particles of infectious
matter, so small as to be wafted by the wind or to adhere to
smooth paper, will multiply so rapidly as to infect within a
short time the whole body of a large animal. We should
also reflect on the admitted number and minuteness of
the molecules composing a particle of ordinary matter.
The difficulty, therefore, which at first appears insurmount-
able, of believing in the existence of gemmules so numerous
S9

898 PROVISIONAL HYPOTHESIS Chap. XXYU.

and small as they must be according to our hypothesis, has
no great weight.

The units of the body are generally admitted by physiolo-
gists to be autonomous. I go one step further and assume
that they throw off rej)roductive gemmules. Thus an organ-
ism does not generate its kind as a whole, but each separate
unit generates its kind. It has often been said by naturalists
that each cell of a plant has the potential capacity of repro-
ducing the whole plant ; but it has this power only in virtue
of containing gemmules derived from every part. When a
cell or unit is from some cause modified, the gemmules derived
from it will be in like manner modified. If our hypothesis
be provisionally accepted, we must look at all the forms of
asexual reproduction, whether occurring at maturity or during
youth, as fundamentally the same, and dependent on the
mutual aggregation and multiplication of the gemmules.
The re-growth of an amputated limb and the healing of a
wound is the same process partially carried out. Buds
apparently include nascent cells, belonging to that stage of
development at which the budding occurs, and these cells are
ready to unite with the gemmules derived from the next
succeeding cells. The sexual elements, on the other hand,
do not include such nascent cells ; and the male and female
elements taken separately do not contain a sufficient number
of gemmules for independent development, except in the
cases of parthenogenesis. The development of each being,
including all the forms of metamorphosis and metagenesis,
depends on the presence of gemmules thrown off at each
period of life, and on their development, at a corresj)onding
period, in union with preceding cells. Such cells may be
said to be fertilised by the gemmules which come next in due
order of development. Thus the act of ordinary impreg-
nation and the development of each part in each being are
closely analogous processes. The child, strictly speaking,
does not grow into the man, but includes germs which slowly
and successively become developed and form the man. In
the child, as well as in the adult, each part generates the
same part. Inheritance must be looked at as merely a form
of growth, like the self-division of a lowly-organised uni-

Chap. XXVII. OF PANGENESIS. 399

cellular organism. Eeversion depends on the transmission
from the forefather to his descendants of dormant gemmules,
which occasionally become developed under certain known or
unknown conditions. Each animal and plant may be com-
pared with a bed of soil full of seeds, some of which soon
germinate, some lie dormant for a period, whilst others
perish. When we hear it said that a man carries in his
constitution the seeds of an inherited disease, there is much
truth in the expression. Xo other attempt, as far as I am
aware, has been made, imperfect as this confessedly is, to
connect under one point of view these several grand classes
of facts. An organic being is a microcosm — a little universe,
formed of a host of self-propagating organisms, inconceivably
minute and numerous as the stars in heaven.

iOO CONCLUDING REMAEKS. Chap. XXVUI.

CHAPTER XXVIII.

CONCLUDING REMARKS.

DOMESTICATION — NATURE AND CAUSES OF VARIABILITY — SELECTION — DIVER-
GENCE AND DISTINCTNESS OP CHARACTER EXTINCTION OP RACES-
CIRCUMSTANCES FAVOURABLE TO SELECTION BY MAN — ANTIQUITY OP
CERTAIN RACES — THE QUESTION WHETHER EACH PARTICULAR VARIATION
HAS BEEN SPECIALLY PREORDAINED.

As siiminaries have been added to nearljT- all tlie cliapters, and
as, in the chapter on pangenesis, various subjects, such as the
forms of reproduction, inheritance, reversion, the causes and
laws of variability, &c., have been recently discussed, I will
here only make a few general remarks on the more important
conclusions which may be deduced from the multifarious
details given throughout this work.

Savages in all parts of the world easily succeed in taming
wild animals ; and those inhabiting any country or island,
when first visited by man, would probably have been still
more easily tamed. Complete subjugation generally depends
on an animal being social in its habits, and on receiving man
as the chief of the herd or family. In order that an animal
should be domesticated it must be fertile under changed con-
ditions of life, and this is far from being always the case. An
animal would not have been worth the labour of domestica-
tion, at least during early times, unless of service to man.
From these circumstances the number of domesticated animals
has never been large. With respect to plants, I have shown
in the ninth chapter how their varied uses were probabl}'-
first discovered, and the early steps in their cultivation. Man
could not have known, when he first domesticated an animal
or plant, whether it would flourish and multiply when trans-
ported to other countries, therefore he could not have been
thus influenced in his choice. We see that the close adapta-
tion of the reindeer and camel to extremely cold and hot

Chap. XXVIIL CONCLUDING KEMARKS. 401

countries has not prevented tlieir domestication. Still less
could man have foreseen whether his animals and plants
would vary in succeeding generations and thus give birth to
new races ; and the small capacity of variability in the goose
has not prevented its domestication from a remote epoch.

With extremely few exceptions, all animals and plants
M^hich have been long domesticated have varied greatly. It
matters not under wliat climate, or for what purpose they are
kept, whether as food for man or beast, for draught or hunt-
ing, for clothing or mere pleasure, — under all these circum-
stances races have been produced which differ more from one
another than do the forms which in a state of nature are
ranked as different species. Why certain animals and plants
have varied more under domestication than others we do not
know, any more than why some are rendered more sterile
than others under changed conditions of life. But we have
to judge of the amount of variation which our domestic pro-
ductions have undergone, chiefly by the number and amount
of difference between the races which have been formed, and
we can often clearly see why many and distinct races have
not been formed, namely, because slight successive variations
have not been steadily accumulated ; and such variations will
never be accumulated if an animal or plant be not closely
observed, much valued, and kept in large numbers.

The fluctuating, and, as far as we can judge, never-ending
variability of our domesticated productions, — the plasticity of
almost their whole organisation, — is one of the most important
lessons which we learn from the numerous details given in
the earlier chapters of this work. Yet domesticated animals
and plants can hardly have been exposed to greater changes
in their conditions of life than have many natural species
during the incessant geological, geographical, and climatal
changes to which the world has been subject; but domes-
ticated productions will often have been exposed to more
sudden changes and to less continuously uniform conditions.
As man has domesticated so many animals and plants be-
longing to widely different classes, and as he certainly did not
choose with prophetic instinct those species which would vary
most, we may infer that all natural species, if exposed to

102 CONCLUDING KEMAEKS. Chap. XX VIII.

analogous conditions, would, on an average, vary to the same
degree. Few men at the present day will maintain that
animals and plants were created with a tendency to vary,
which long remained dormant, in order that fanciers in after
ages might rear, for instance, curious breeds of the fowl,
pigeon, or canary-bird.

From several causes it is difficult to judge of the amount
of modification which our domestic productions have under-
gone. In some cases the primitive parent-stock has become
extinct ; or it cannot be recognised with certainty, owing to
its supposed descendants having been so much modified. In
other cases two or more closely-allied forms, after being
domesticated, have crossed ; and then it is difficult to estimate
how much of the character of the present descendants ought
to be attributed to variation, and how much to the influence
of the several parent-stocks. But the degree to which our
domesticated breeds have been modified by the crossing of
distinct sjDecies has probably been much exaggerated by some
authors. A few individuals of one form would seldom per-
manently affect another form existing in greater numbers ;
for, without careful selection, the stain of the foreign blood
would soon be obliterated, and during early and barbarous
times, when our animals were first domesticated, such care
would seldom have been taken.

There is good reason to believe in the case of the dog, ox,
pig, and of some other animals, that several of our races are
descended from distinct wild prototypes ; nevertheless the
belief in the multiple origin of our domesticated animals has
been extended by some few naturalists and by many breeders
to an unauthorised extent. Breeders refuse to look at the
whole subject under a single point of view ; I have heard
it said by a man, who maintained that our fowls were de-
scended from at least half-a-dozen aboriginal species, that the
evidence of the common origin of pigeons, ducks and rabbits,
was of no avail with respect to fowls. Bieeders overlook
the improbability of many species having been domesticated
at an early and barbarous period. They do not consider the
improbability of species having existed in a state of nature
which, if they resembled our present domestic breeds, would

Chap. XXVIII. CONCLUDING KEMARKS. 403

have been highly abnormal in comparison with all their
congeners. They maintain that certain species, which
formerly existed, have become extinct, or are now unknown,
although formerly known. The assumption of so much
recent extinction is no difficulty in their eyes ; for they do
not judge of its probability by the facility or difficult}'' of the
extinction of other closely-allied wild forms. Lastly, they
often ignore the whole subject of geographical distribution as
completely as if it were the result of chance.

Although from the reasons just assigned it is often difficult
to judge accurately of the amount of change which our
domesticated productions have undergone, yet this can be
ascertained in the cases in which all the breeds are known
to be descended from a single species, — as with the pigeon,
duck, rabbit, and almost certainly with the fowl ; and by the
aid of analogy this can be judged of to a certain extent with
domesticated animals descended from several wild stocks. It
is impossible to read the details given in the earlier chapters
and in many published works, or to visit our various ex-
hibitions, without being deeply impressed with the extreme
variability of our domesticated animals and cultivated plants.
No part of the organisation escapes the tendency to vary.
The variations generally affect parts of small vital or physio-
logical importance, but so it is with the differences which
exist between closely-allied species. In these unimportant
characters there is often a greater difference between the
breeds of the same species than between the natural species
of the same genus, as Isidore Geoffrey has shown to be the
case with size, and as is often the case with the colour,
texture, form, &c., of the hair, feathers, horns, and other
dermal appendages.

It has often been asserted that important parts never vary
under domestication, but this is a complete error. Look at
the skull of the pig in any one of the highly improved breeds,
with the occipital condyles and other parts greatly modified ;
or look at that of the niata ox. Or, again, in the several
breeds of the rabbit, observe the elongated skull, with the
differently shaped occipital foramen, atlas, and other cervical
vertebrae. The whole shape of the brain, together with the

i04 CONCLUDING REMARKS. Chap. XXYIIl.

skull, lias been modified in Polish fowls ; in other breeds of
the fowl the number of the vertebrae and the forms of the
cervical vertebrss have been changed. In certain pigeons the
shape of the lower jaw, the relative length of the tongue, the
size of the nostrils and eyelids, the number and shape of the
ribs, ihe form and size of the oesophagus, have all varied. In
certain quadrupeds the length of the intestines has been much
increased or diminished. With plants we see wonderful-
differences in the stones of various fruits. In the Cucur-
bitaceae several highly important characters have varied, such
as the sessile position of the stigmas on the ovarium, the
position of the carpels, and the projection of the ovarium out
of the receptacle. But it would be useless to run through
the many facts given in the earlier chapters.

It is notorious how greatly the mental disposition, tastes,
habits, consensual movements, loquacity or silence, and tone
of voice have varied and been inherited in our domesticated
animals. The dog offers the most striking instance of changed
mental attributes, and these differences cannot be accounted
for by descent from distinct wild types.

New characters may appear and old ones disappear at any
stage of development, being inherited at a corresponding
stage. We see this in the difference between the eggs, the
down on the chickens and the first plumage of the various
breeds of the fowl ; and still more plainly in the differences
between the caterpillars and cocoons of the various breeds of
the silk-moth. These facts, simple as they appear, throw light
on the differences between the larval and adult states of
allied natural species, and on the whole great subject of em-
bryology. New characters first appearing late in life are apt
to become attached exclusively to that sex in which they
first arose, or they may be developed in a much higher degree
in this than in the other sex ; or again, after having become
attached to one sex, they may be transferred to the opposite
sex. These facts, and more especially the circumstance that
new characters seem to be particularly liable, from some
anknown cause, to become attached to the male sex, have an
important bearing on the acquirement of secondary sexual
characters by animals in a state of nature.

Chap. XXVIII. CONCLUDING REMARKS. 405

It has sometimes been said that our domestic races do not
differ in constitutional peculiarities, but this cannot be main-
tained. In our improved cattle, pigs, &c., the period of
maturit}', including that of the second dentition, has been
much hastened. The period of gestation varies much, and
has been modified in a fixed manner in one or two cases. In
some breeds of poultry and pigeons the period at which the
down and the first plumage are acquired, differs. The number
of moults through which the larvae of silk-moths j)ass, varies.
The tendency to fatten, to yield much milk, to produce many
young or eggs at a birth or during life, differs in different
breeds. We find different degrees of adaptation to climate,
and different tendencies to certain diseases, to the attacks of
parasites, and to the action of certain vegetable poisons.
AVith plants, adaptation to certain soils, the power of resisting
frost, the period of flowering and fruiting, the duration of
life, the period of shedding the leaves or of retaining them
throughout the •winter, the proportion and nature of certain
chemical compounds in the tissues or seeds, all vary.

There is, however, one important constitutional difference
between domestic races and species ; I refer to the sterility
which almost invariably follows, in a greater or less degree,
when species are crossed, and to the perfect fertility of the
most distinct domestic races, with the exception of a very
few plants, when similarly crossed. It is certainly a most
remarkable fact that many closely-allied species, which in
appearance differ extremely little, should yield when crossed
only a few more or less sterile offspring, or none at all ;
whilst domestic races which differ conspicuously from each
other are, when united, remarkably fertile, and yield perfectly
fertile offspring. But this fact is not in reality so inexplicable
as it at first appears. In the first place, it was clearly shown
in the nijieteenth chapter that the sterility of crossed species
does not depend chiefly on differences in their external struc-
ture or general constitution, but on differences in the repro-
ductive system, analogous to those which cause the lessened
fertility of the illegitimate unions of dimorphic and trimorphic
plants. In the second place, the Pallasian doctrine, that
species after having been long domesticated lose their natural

40G CONCLUDING REMARKS. Chap. XXVUI.

tendency to sterility when crossed, lias been shown to be
highly probable or almost certain. We cannot avoid this
conclusion when we reflect on the parentage and present
fertility of the several breeds of the dog, of the Indian or
humped and European cattle, and of the two chief kinds of
pigs. Hence it would be unreasonable to expect that races
formed under domestication should acquire sterility when
crossed, whilst at the same time we admit that domestication
eliminates the normal sterility of crossed species. Why with
closely-allied species their rej)roductive systems should almost
invariably have been modified in so peculiar a manner as to
be mutually incapable of acting on each other — though in un-
equal degrees in the two sexes, as shown by the difference in
fertility between reciprocal crosses of the same species — we
do not know, but may with much probability infer the cause
to be as follows. Most natural species have been habituated to
nearly uniform conditions of life for an incomparably longer
time than have domestic races ; and we positively know that
changed conditions exert an especial and powerful influence
on the reproductive system. Hence this difference may well
account for the difference in the power of reproduction between
domestic races when crossed and species when crossed. It is
probably in chief j^art owing to the same cause that domestic
races can be suddenly transported from one climate to
another, or placed under widely different conditions, and yet
retain in most cases their fertility unimpaired ; whilst a
multitade of species subjected to lesser changes are rendered
incapable of breeding.

The offspring of crossed domestic races and of crossed
species resemble each other in most respects, with the one im-
portant exception of fertility ; they often partake in the same
unequal degree of the characters of their parents, one of
which is often prepotent over the other ; and they are liable
to reversion of the same kind. By successive crosses one
species may be made to absorb completely another, and so
it notoriously is with races. The latter resemble species in
many other ways. They sometimes inherit their newly-
acquired characters almost or even quite as firmly as species.
The conditions leading to variability and the laws governing

Chap. XXVIII. CONCLUDING REMARKS. 407

its nature appear to be the same in both. Varieties can be
classed in groups under groups, like species under genera, and
these under families and orders ; and the classification may
be either artificial, — that is, founded on any arbitrary cha-
racter,— or natural. With varieties a natural classification
is certainly founded, and with species is apparently founded,
on community of descent, together with the amount of modi-
fication which the forms have undergone. The characters
by which domestic varieties differ from one another are more
variable than those distinguishing species, though hardly
more so than with certain poljanorphic species; but this
greater degree of variability is not surprising, as varieties
have generally been exposed within recent times to fluctu-
ating conditions of life, and are much more liable to have
been crossed ; they are also in many cases still undergoing,
or have recently undergone, modification by man's methodical
or unconscious selection.

Domestic varieties as a general rule certainly differ from
one another in less important parts than do species; and
when important differences occur, the}' are seldom firmly
fixed; but this fact is intelligible, if we consider man's
iiethod of selection. In the living animal or plant he cannot
observe internal modifications in the more important organs ;
nor does he regard them as long as they are compatible with
health and life. What does the breeder care about any
slight change in the molar teeth of his pigs, or for an ad-
ditional molar tooth in the dog ; or for any change in the
intestinal canal or other internal organ ? The breeder cares
for the flesh of his cattle being well marbled Avith fat, and
for an accumulation of fat within the abdomen of his sheep,
and this he has effected. What would the floriculturist care
for any change in the structure of the ovarium or of the
ovules ? As important internal organs are certainly liable
to numerous slight variations, and as these would probably
be transmitted, for many strange monstrosities are inherited,
man could undoubtedly effect a certain amount of change in
these organs. When he has produced any modification in an
important part, he has generally done so unintentionally,
in correlation with some other conspicuous part. For in-
stance, he has given ridges and protuberances to the skulls

108 CONCLUDING EEMARKS. Chap. XXVllI.

of fowls, by attending to tiie form of the comb, or to the
plume of feathers on the head. By attending to the external
form of the pouter-pigeon, he has enormously increased the
size of the oesophagus, and has added to the number of the
ribs, and given them greater breadth. With the carrier-
pigeon, by increasing through steady selection the wattles
on the upper mandible, he has greatly modified the form of
the lower mandible ; and so in man}^ other cases. Natural
species, on the other hand, have been modified exclusively
for their own good, to fit them for infinitely diversified con-
ditions of life, to avoid enemies of all kinds, and to struggle
against a host of competitors. Hence, under such complex
conditions, it would often happen that modifications of the
most varied kinds, in important as well as in unimportant
parts, would be advantageous or even necessary ; and they
would slowly but surely be acquired through the survival
of the fittest. Still more important is the fact that various
indirect modifications would likewise arise through the law
of correlated variation.

Domestic breeds often have an abnormal or semi-monstrous
character, as amongst dogs, the Italian greyhound, bulldog,
Blenheim spaniel, and bloodhound, — some breeds of cattle
and pigs, — several breeds of the fowl, — and the chief breeds
of the pigeon. In such abnormal breeds, parts which differ
but slightly or not at all in the allied natural species, have
been greatly modified. This may be accounted for by man's
often selecting, especially at first, conspicuous and semi-
monstrous deviations of structure. We should, however,
be cautious in deciding what deviations oiight to be called
monstrous : there can hardly be a doubt that, if the brush
of horse-like hair on the breast of the turkey-cock had first
appeared in the domesticated bird, it would have been con-
sidered as a monstrosity ; the great plume of feathers on the
head of the Polish cock has been thus designated, though
plumes are common on the heads of many kinds of birds ;
w-e might call the wattle or corrugated skin round the base
of the beak of the English carrier-pigeon a monstrosity,
but we do not thus speak of the globular fleshy excrescence
at the base of the beak of the Carpopliaga oceanica.

Some authors have drawn a wide distinction between

Chap. XXVin. CONCLUDING EEMAEKS. 409

artificial and natural breeds ; altlioiigli in extreme cases the
distinction is plain, in many other cases it is arbitrary ; the
difierence depending chiefly on the kind of selection which
has been applied. Artificial breeds are those which have
been intentionally improved by man ; they frequently have
an unnatural appearance, and are especially liable to lose
their characters through reversion and continued variability.
The so-called natural breeds, on the other hand, are those
which are found in semi-civilised countries, and which
formerly inhabited se^^arate districts in nearly all the
European kingdoms. They have been rarely acted on by
man's intentional selection ; more frequently by unconscious
selection, and partly by natural selection, for animals kej)t
in semi-civilised countries have to provide largely for their
own wants. Such natural breeds will also have been directly
acted on by the differences, though slight, in the surrounding-
conditions.

There is a much more important distinction between our
several breeds, namely, in some having originated from a
strongly-marked or semi-monstrous deviation of structure,
which, however, may subsequently have been augmented
by selection; whilst others have been formed in so slow
and insensible a manner, that if we could see their earl}^ pro-
genitors we should hardly be able to say when or how the
breed first arose. From the history of the racehorse, grey-
hound, gamecock, &c., and from their general appearance,
we may feel nearly confident that they were formed by a
slow process of improvement ; and we know that this has
been the case with the carrier- j)igeon, as well as with some
other pigeons. On the other hand, it is ceitain that the
ancon and mauchamp breeds of sheep, and almost certain
that the niata cattle, turnspit, and pug-dogs, jumper and
frizzled fowls, short-faced tumbler pigeons, hook-billed ducks,
&c., suddenly appeared in nearly the same state as we now
see them. So it has been with many cultivated plants. The
frequency of these cases is likely to lead to the false belief
that natural species have often originated in the same abrupt
manner. But we have no evidence of the appearance, or at
least of the continued procreation, under nature, of abrupt

ilO CONCLUDING REMARKS. Chap. XXVIIl.

modifications of structure ; and various general reasons could
be assigned against such a belief.

On the other hand, we have abundant evidence of the
constant occurrence under nature of slight individual differ-
ences of the most diversified kinds ; and we are thus led to
conclude that species have generally originated by the natural
selection of extremely slight differences. This process may
be strictly compared with the slow and gradual improvement
of the racehorse, greyhound, and gamecock. As every detail
of structure in each species has to be closely adapted to its
habits of life, it will rarel}^ happen that one part alone will
be modified; but, as was formerly shown, the co-adapted
modifications need not be absolutely simultaneous. Many
variations, however, are from the first connected by the law of
correlation. Hence it follows that even closely-allied species
rarely or never differ from one another by one character
alone ; and the same remark is to a certain extent applicable
to domestic races ; for these, if they differ much, generally
differ in many respects.

Some naturalists boldly insist ^ that species are absolutely
distinct productions, never passing by intermediate links into
one another ; whilst they maintain that domestic varieties
can always be connected either with one another or with their
parent-forms. But if we could always find the links between
the several bre»-ds of the dog, horse, cattle, sheep, pigs, &c.,
there would r-ot have been such incessant doubts whether
they were descended from one or several species. The grey-
hound genus, if such a term may be used, cannot be closely
connected with any other breed, unless, perhaps, we go back to
the ancient Egj^Dtian monuments. Our English bulldog also
forms a very distinct breed. In all these cases crossed breeds
must of coui'se be excluded, for distinct natural species can
thus be likewise connected. By what links can the Cochin
fowl be closely united with others ? By searching for breeds
still preserved in distant lands, and by going back to
historical records, tumbler-pigeons, carriers, and barbs can
be closely connected with the parent rock-pigeon ; but wfl

* Godron, ' De TEspece,' 1859, torn. ii. p. 44, &c.

Chap. XXVIII. CONCLUDING EEMARKS. 411

cannot thus connect the turbit or the pouter. The degree
of distinctness between the various domestic breeds depends
on the amount of modification which they have undergone,
and more especially on the neglect and final extinction of
intermediate and less-valued forms.

It has often been argued that no light is thrown on the
changes which natural species are believed to undergo from
the admitted changes of domestic races, as the latter are
said to be mere temporary j)i'oductions, always reverting,
as soon as they become feral, to their pristine form. This
argument has been well combated by Mr. Wallace ; ^ and
full details were given in the thirteenth chapter, showing
that the tendency to reversion in feral animals and plants
has been greatly exaggerated, though no doubt it exists to
a certain extent. It would be opposed to all the principles
inculcated in this work, if domestic animals, when exposed
to new conditions and compelled to struggle for their
own wants against a host of foreign competitors, were not
modified in the course of time. It should also be remem-
bered that many characters lie lateat in all organic beings,
ready to be evolved under fitting conditions ; and in breeds
modified within recent times, the tendency to reversion is
particularly strong. But the antiquity of some of our breeds
clearly proves that they remain nearly constant as long as
their conditions of life remain the same.

It has been boldly maintained by some authors that the
amount of variation to which our domestic productions are
liable is strictly limited ; but this is an assertion resting on
little evidence. Whether or not the amount of change in
any particular direction is limited, the tendency to general
variability is, as far as we can judge, unlimited. Cattle,
fciheep, and pigs have varied under domestication from the
remotest period, as shown by the researches of Rtitimeyer
and others ; yet these animals have been improved to an
unparalleled degree, within quite recent times, and this
imiDlies continued variability of structure. Wheat, as we
know from the remains found in the Swiss lake-dwellings,

^ ' Journal Proc. Linu. Soc.,' I808, vol. iii. p. 60.

412 CONCLUDING KEMARKS. Chap. XXVIII.

is one of the most anciently cultivated plants, yet at the
present day new and better varieties frequently arise. Tt
may be that an ox will never be produced of larger size and
finer proportions, or a racehorse fleeter, than our present
animals, or a gooseberry larger than the London variety ;
but he would be a bold man who would assert that the
extreme limit in these respects has been finally attained.
With flowers and fruit it has repeatedly been asserted that
perfection has been reached, but the standard has soon been
excelled. A breed of pigeons may never be produced with a
beak shorter than that of the present short-faced tumbler, or
with one longer than that of the English carrier, for these
birds have weak constitutions and are bad breeders ; but short-
ness and length of beak are the points which have been
steadily improved during the last 150 years, and some of
the best judges deny that the goal has yet been reached.
From reasons which could be assigned, it is probable that
parts which have now reached their maximum development,
might, after remaining constant during a long period, vary
again in the direction of increase under new conditions of
life. But there must be, as Mr. Wallace has remarked with
much truth,^ a limit to change in certain directions both
with natural and domestic productions; for instance, there
must be a limit to the fleetness of an}- terrestrial animal,
as this Avill be determined by the friction to be overcome,
the weight to be carried, and the power of contraction in the
muscular fibres. The English racehorse may have reached
this limit ; but it already surpasses in fleetness its own wild
progenitor and all other equine species. The short-faced
tumbler-pigeon has a beak shorter, and the carrier a beak
longer, relatively to the size of their bodies, than that of any
natural species of the family. Our apples, pears and goose-
berries bear larger fruit than those of any natural species
of the same genera ; and so in many other cases.

It is not surprising, seeing the great difierence between

many domestic breeds, that some few naturalists have con-

3luded that each is descended from a distinct aboriginal stock,

more especially as the principle of selection has been ignored,

3 ' The Quarterly Journal of Science,* Oct. 1867, p. 486.

Chap. XXYIII. CONCLUDING REMARKS. 413

and the higii antiquity of man, as a breeder of animals, haa
only recently become knoAvn. Most naturalists, bowever,
freel}^ admit that our various breeds, however dissimilar,
are descended from a single stock, although they do not
know much about the art of breeding, cannot show the
connecting links, nor say where and when the breeds arose.
Yet these same naturalists declare, with an air of philo-
sophical caution, that they will never admit that one natural
species has given birth to another until they behold all the
transitional steps. Fanciers use exactly the same language
with respect to domestic breeds ; thus, an author of an excellent
treatise on pigeons says he will never allow that the carrier
and fantail are the descendants of the wild rock-pigeon,
until the transitions have " actually been observed, and can
" be repeated whenever man chooses to set about the task."
Ko doubt it is difficult to realise that slight changes added
up during long centuries can produce such great results;
but he Avho T\dshes to understand the origin of domestic breeds
or of natural species must overcome this difficult}^.

The causes which excite and the laws which govern varia-
bility have been discussed so lately, that I need here only
enumerate the leading points. As domesticated organisms are
much more liable to slight deviations of structure and to mon-
strosities than species living under their natural conditions,
and as widely-ranging species generally vary more than those
which inhabit restricted areas, we may infer that variability
mainly depends on changed conditions of life. We must not
overlook the effects of the unequal combination of the charac-
ters derived from both parents, or reversion to former pro-
genitors. Changed conditions have an especial tendency to
render the reproductive organs more or less impotent, as
shown in the chapter devoted to this subject ; and these
organs consequently often fail to transmit faithfully the
parental characters. Changed conditions also act directly
and definitely on the organisation, so that all or nearly all
the individuals of the same species thus exposed become
modified in the same manner ; but why this or that part is
especially affected we can seldom or ever say. In most
cases, however, a change in the conditions seems to act

414 CONCLUDING REMARKS. Chap. XXVIII.

indefinitely, causing diversified variations in nearly the
same manner as exj^osure to cold or the absorption of the
same poison affects different individuals in different ways.
We have reason to suspect that an habitual excess of highly-
nutritious food, or an excess relatively to the wear and tear
of the organisation from exercise, is a powerful exciting cause
of variability. AVhen we see the symmetrical and complex
outgrowths, caused by a minute drop of the poison of a gall-
insect, we may believe that slight changes in the chemical
nature of the sap or blood would lead to extraordinary modi
fications of structure.

The increased use of a muscle with its various attached
parts, and the increased activity of a gland or other organ,
lead to their increased development. Disuse has a contrary
effect. With domesticated productions, although their organs
sometimes become rudimentary through abortion, we have no
reason to suppose that this has ever followed solely from
disuse. With natural species, on the contrar}^, many organs
appear to have been rendered rudimentary through disuse,
aided by the principle of the economy of growth together
with intercrossing. Complete abortion can be accounted for
only by the hypothesis given in the last chapter, namely, the
final destruction of the germs or gemmules of useless parts.
This difference between species and domestic varieties may
be partly accounted for by disuse having acted on the
latter for an insiifficient length of time, and partly from
their exemption from any severe struggle for existence
entailing rigid economy in the development of each part, to
which all species under nature are subjected. Nevertheless
the law of compensation or balancement, which likewise
depends on the economy of growth, apparently has affected
to a certain extent our domesticated productions.

As almost exeiy part of the organisation becomes highly
variable under domestication, and as variations are easily
selected both consciously and unconsciously, it is very diffi-
cult to distinguish between the effects of the selection of
indefinite variations and the direct action of the conditions
of life. For instance, it is possible that the feet of our water-
dogs and of the American dogs which have to travel much

Chap. XXVIII. CONCLUDING REMARKS. 415

over tlie snow, may have become partially webbed from the
stimulus of widely extending their toes ; but it is more pro-
bable that the webbing, like the membrane between the toes
of certain pigeons, spontaneously appeared and was afterwards
increased by the best swimmers and the best snow-travellers
being preserved during many generations. A fancier who
wished to decrease the size of his bantams or tumbler-pigeons
would never think of starving them, but would select the
smallest individuals which spontaneously appeared. Quad-
rupeds are sometimes born destitute of hair and hairless
breeds have been formed, but there is no reason to believe
that this is caused by a hot climate. Within the tropics heat
often causes sheep to lose their fleeces ; on the other hand,
wet and cold act as a direct stimulus to the growth of hair ;
but who will pretend to decide how far the thick fur of arctic
animals, or their white colour, is due to the direct action of
a severe climate, and how far to the preservation of the best-
protected individuals during a long succession of genera-
tions ?

Of all the laws governing variability, that of correlation is
one of the most important. In many cases of slight deviations
of structure as well as of grave monstrosities, we cannot even
conjecture what is the nature of the bond of connexion. But
between homologous parts — between the fore and hind limbs
— between the hair, hoofs, horns, and teeth — which are closely
similar during their early development and which are exposed
to similar conditions, we can see that they would be eminently
liable to be modified in the same manner. Homologous parts,
from having the same nature, are apt to blend together, and,
when many exist, to vary in number.

Although every variation is either directly or indirectly
caused by some change in the surrounding conditions, we
must never fovget that the nature of the organisation which
is acted on, is by far the more important factor in the result.
We see this in different organisms, which when placed under
eimilar conditions vary in a different manner, whilst closely-
allied organisms under dissimilar conditions often vary in
nearly the same manner. We see this, in the same modifica-
tion frequently reappearing in the same variety at long

il6 CONCLUDING KEMAEKS. Chap. XXVI IL

intervals of time, and likewise in tlie several striking cases
given of analogous or parallel variations. Althougb. some
of these latter cases are due to reversion, others cannot thus
be accounted for.

From the indirect action of changed conditions on the
organisation, owing to the reproductive organs being thus
affected — from the direct action of such conditions, and these
will cause the individuals of the same species either to vary
in the same manner, or differently in accordance with slight
differences in their constitution — from the effects of the in-
creased or decreased use of parts — and from correlation, —
the variability of our domesticated productions is complicated
to an extreme degree. The whole organisation becomes
slightly plastic. Although each modification must have its
own exciting cause, and though each is subjected to law,
yet we can so rarely trace the precise relation between cause
and effect, that we are tempted to speak of variations as if
they arose spontaneously. We may even call them accidental,
but this must be only in the sense in which we say that
a fragment of rock dropped from a height owes its shape to
accident.

It may be worth while briefly to consider the result of the
. exposure to unnatural conditions of a large number of animals
of the same species and allowed to cross freely with no
selection of any kind, and afterwards to consider the result
when selection is brought into play. Let us suppose that
500 wild rock-pigeons were confined in their native land in
an aviary and fed in the same manner as pigeons usually
are ; and that they were not allowed to increase in number.
As pigeons propagate so rapidly, I suppose that a thousand
or fifteen hundred birds would have to be annually killed.
After several generations had been thus reared, we may
feel sure that some of the young birds would vary, and
the variations would tend to be inherited ; for at the
present day slight deviations of structure often occur and
are inherited. It would be tedious even to enumerate the
multitude of points which still go on varying or have
recently varied. Many variations would occur in correla-

Chap. XXVIII. CONCLUDING KEMARKS. 417

tion with one anotlier, as the length of the Mdng and
tail feathers — the number of the primary wing-feathers, as
well as the number and breadth of the ribs, in correlation
with the size and form of the body — the number of the
ecutelhe with the size of the feet — the length of the tongue
with the length of the beak — the size of the nostrils and
eyelids and the form of lower jaw in correlation with the
development of wattle — the nakedness of the young with the
future colour of the plumage — the size of the feet with that
of the beak, and other such points. Lastly, as our birds are
supposed to be confined in an aviary, they would use their
wings and legs but little, and certain parts of the skeleton,
such as the sternum, scapulte and feet, would in consequence
become slightly reduced in size.

As in our assumed case many birds have to be indiscrimi-
nately killed every year, the chances are against any new
variety surviving long enough to breed. And as the varia-
tions which arise are of an extremely diversified nature, the
chances are very great against two birds pairing which have
varied in the same manner; nevertheless, a varying bird
even when not thus paii-ed would occasionally transmit its
character to its young ; and these would not only be exposed
to the same conditions which first caused the variation in
question to appear, but would in addition inherit from their
modified parent a tendency again to vary in the same manner.
So that, if the conditions decidedly tended to induce some
particular variation, all the birds might in the course of time
become similarly modified. But a far commoner result would
be, that one bird would vary in one way and another bird in
another way ; one would be born with a beak a little longer,
and another with a shorter beak; one would gain some black
feathers, another some white or red feathers. And as these
birds would be continually intercrossing, the final result would
be a body of individuals difiering from each other in many
ways, but onl}'- slightly; yet more than did the original rock-
pigeons. But there would not be the least tendency towards
the formation of several distinct breeds.

If two separate lots of pigeons were treated in the manner
just described, one in England and the other in a trojiical

418 CONCLUDING REMARKS. Chap. XXVIII.

conntrj, the two lots being supplied with different kinds of
Ibod, would tliey iafter many generations differ ? "When we
reflect on the cases given in the twenty-third chapter, and
on such facts as the difference in former tim^s between the
breeds of cattle, sheep, &c., in almost every district of Europe,
we are strongly inclined to admit that the two lots would be
differently modified through the influence of climate and food.
But the evidence on the definite action of changed conditions
is in most cases insufficient ; and, with respect to pigeons, I
have had the opportunity of examining a large collection of
domesticated kinds, sent to me by Sir "W. Elliot from India,
and they varied in a remarkably similar manner with our
European birds.

If two distinct breeds were mingled together in equal
numbers, there is reason to suspect that they would to a
certain extent prefer pairing with their own kind ; but they
would often intercross. From the greater vigour and fertility
of the crossed offspring, the whole body would by this means
become interblended sooner than would otherwise have oc-
curred. From certain breeds being prepotent over others, it
does not follow that the interblended progeny would be strictly
intermediate in character, I have, also, proved that tlie act
of crossing in itself gives a strong tendency to reversion, so
that the crossed offsj)ring would tend to revert to the state
of the aboriginal rock-pigeon ; and in the course of time they
would probably be not much more heterogeneous in character
than in our first case, when birds of the same breed were
confined together.

I have just said that the crossed offspring would gain in
vigour and fertility. From the facts given in the seventeenth
chapter there can be no doubt of this fact ; and there can be
little doubt, though the evidence on this head is not so easily
acquired, that long-continued close interbreeding leads to evil
results. With hermaphrodites of all kinds, if the sexual ele-
ments of the same individual habitually acted on each other,
the closest possible interbreeding would be perpetual. But
wo should bear in mind that the structure of all herma-
phrodite animals, as far as I can learn, permits and fre-
quently necessitates a cross with a distinct individual. With

Chap. XXVIII. CONCLUDING IIE3IARKS. 419

hermaplirodite plants we incessantly meet with elaborate and
perfect contrivances for this same end. It is no exagge-
ration to assert that, if the use of the talons and tusks of a
carnivorous animal, or of the plumes and hooks on a seed, may
be safely inferred from their structure, we may with equal
safety infer that many flowers are constructed for the express
purpose of ensuring a cross with a distinct plant. From
these various considerations, not to mention the result of a
long series of experiments which I have tried, the conclusion
arrived at in the chapter just referred to — namely, that great
good of some kind is derived from the sexual concourse of
distinct individuals — must be admitted.

To return to our illustration : we have hitherto assumed
that the birds were kept down to the same number by indis-
criminate slaughter ; but if the least choice be permitted in
their preservation, the whole result will be changed. Should
the owner observe any slight variation in one of his birds,
and wish to obtain a breed thus characterised, he would succeed
in a surprisingly short time by careful selection. As any
part which has once~varied generally goes on varying in the
same direction, it is easy, by continually preserving the most
strongly marked individuals, to increase the amount of differ-
ence up to a high, predetermined standard of excellence.
This is methodical selection.

If the owner of the aviary, without any thought of making
a new breed, simply admired, for instance, short-beaked more
than long-beaked birds, he would, when he had to reduce the
number, generally kill the latter ; and there can be no doubt
that he would thus in the course of time sensibly modify his
stock. It is improbable, if two men were to keep pigeons
and act in this manner, that they would prefer exactly the
same characters ; they would, as we know, often prefer
directly opjoosite characters, and the two lots would ulti-
mately come to differ. This has actually occurred with
strains or families of cattle, sheep, and pigeons, which have
been long kept and carefully attended to b}^ different breeders,
without any wish on their part to form new and distinct sub-
breeds. This unconscious kind of selection will more espe-
cially come into action with animals which are highly service-

420 CONCLUDING REMARKS. Chap. XXVIII.

able to man ; for every one tries to get the best dogs, horses,
cows, or sheep, without thinking about their future progeny,
yet these animals would transmit more or less surely their
good qualities to their offspring. Kor is any one so careless
as to breed from his worst animals. Even savages, when
compelled from extreme want to kill some of their animals,
would destroy the worst and preserve the best. With ani-
mals kept for use and not for mere amusement, different
fashions prevail in different districts, leading to the preserva-
tion, and consequently to the transmission, of all sorts of
trifling peculiarities of character. The same process will
have been pursued with our fruit-trees and vegetables, for
the best will always have been the most largely cultivated,
and will occasionally have yielded seedlings better than their
parents.

The different strains, just alluded to, which have been
actually produced by breeders without any wish on their
part to obtain such a result, afford excellent evidence of the
power of unconscious selection. This form of selection has
probably led to far more important results than methodical
selection, and is likewise more important under a theoretical
point of view from closely resembling natural selection. For
during this process the best or most valued individuals are
not separated and prevented from crossing with others of the
same breed, but are simply preferred and preserved ; yet this
inevitably leads to their gradual modification and improve-
•ment ; so that finally they prev^ail, to the exclusion of the old
parent-form.

AVith our domesticated animals natural selection checks
the production of races with any injurious deviation of struc-
ture. In the case of animals which, from being kept by
savages or semi-civilised people, have to provide largely for
their own wants under different circumstances, natural selec-
tion will have played a more important part. Hence it
probably is that they often closely resemble natural species.

As there is no limit to man's desire to possess animals and
plants more and more useful in any respect, and as the fancier
always wishes, owing to fashions running into extremes, to
produce each character more and more strongly pronounced,

Chap. XXVIIl. CONCLUDING REMARKS. 421

there is, througli the prolonged action of methodical and
unconscious selection, a constant tendency in every breed to
become more and more different from its parent-stock ; and
when several breeds have been produced and are valued for
different qualities, to differ more and more from each other.
This leads to Divergence of Character. As improved sub-
varieties and races are slowly formed, the older and less
improved breeds are neglected and decrease in number. When
few individuals of any breed exist within the same locality,
close interbreeding, by lessening their vigour and fertility,
aids in their final extinction. Thus the intermediate links
are lost, and the remaining breeds gain in Distinctness of
Character.

In the chapters on the Pigeon, it was proved by historical
evidence and by the existence of connecting sub-varieties in
distant lands that several breeds have steadily diverged in
character, and that many old and intermediate sub-breeds
have been lost. Other cases could be adduced of the extinc-
tion of domestic breeds, as of the Irish wolf-dog, the old
English hound, and of two breeds in France, one of which
was formerly highly valued.* Mr. Pickering remarks ^ that
" the sheep figured on the most ancient Egyj)tian monuments
" is unknown at the present day ; and at least one variety of
" the bullock, formerly known in Egypt, has in like manner
" become extinct." So it has been with some animals and
with several plants cultivated by the ancient inhabitants of
Europe during the neolithic period. In Peru, Von Tschudi ^
found in certain tombs, apparently prior to the dynasty of the
Incas, two kinds of maize not now known in the country.
With our flowers and culinary vegetables, the production of
new varieties and their extinction has incessantly recurred.
At the present time improved breeds sometimes displace older
breeds at an extraordinarily rapid rate ; as has recently occurred
throughout England with pigs. The Long-horn cattle in
their native home were " suddenly swept away as if by some
" murderous pestilence," by the introduction of Short-horns.'^

* M. Rufz de LavisoE, in ' Bull. Soc. p. 177.

Imp. d'Acclimat.,' Dec. 1862, p. 10U9. ^ Youatt on Cattle, 1834, p. 200.

» 'Races of Man,' 1850, p. 315. On Pigs, see ' Gard. Chronicle,' 1854

* 'Travels in Peru,' Eag. Translat,, p. 410.

40

422 CONCLUDING EEMAEKS. Chap. XXVIII.

What grand results have followed from the long-contiimed
action of methodical and unconscious seleQtion. regulated to a
certain extent by natural selection, we see on everj^ side of us.
Compare the many animals and jDlants which are displayed at
our exhibitions with their parent-forms when these are known,
or consult old historical records with respect to their former
state. Most of our domesticated animals have g-iven rise to
numerous and distinct races, but those which cannot be easilv
subjected to selection must be excepted — such as cats, the
cochineal insect, and the hive-bee. In accordance with what
we know of the process of selection, the formation of our
many races has been slow and gradual. The man who first
observed and preserved a pigeon with its oesophagus a little
enlarged, its beak a little longer, or its tail a little more
expanded than usual, never dreamed that he had made the
first step in the creation of a pouter, carrier, and fantail-
pigeon. Man can create not only anomalous breeds, but
others having their whole structure admirably co-ordinated
for certain purposes, such as the race-horse and dray-horse, or
the greyhound and bulldog. It is by no means necessary
that each small change of structure thronghout the body,
leading towards excellence, should simultaneously arise and
be selected. Although man seldom attends to diiferences in
organs which -are important under a physiological point of
view, vet he has so profoundly modified some breeds, that
asuredly, if found wild, they would be ranked as distinct
genera.

The best proof of what selection has eifected is perhaps
aff"orded by the fact that whatever part or quality in any
animal, and more especially in any plant, is most valued by
man, that part or quality differs most in the several races.
This result is well seen by comparing the amount of difference
between the fruits produced by the several varieties of fruit-
trees, between the flowers of our flower-garden plants, between
the seeds, roots, or leaves of our culinary and agricultural
plants, in comparison with the other and not valued parts of
the same varieties. Striking evidence of a different kind is
afforded by the fact ascertained by Oswald Heer,^ namely,
that the seeds of a large number of plants, — wheat, barley,

8 ' Die Pflanzon der Pfahlbauten,' 1865.

Chap. XXVni. CONCLUDING KEMAEKS. 423

oats, peas, beans, lentils, poppies, — cultivated for their seed
by the ancient Lake-inhabitants of Switzerland, were all
smaller than the seeds of our existing varieties. Riitimeyer
has shown that the sheep and cattle which, were kept by ttie
earlier Lake-inhabitants were likewise smaller than our
present breeds. In the middens of Denmark, the earliest dog
of whicb the remains have been found was the weakest ; this
w^as succeeded during the Bronze age by a stronger kind, and
this again during the Iron age by one still stronger. The
sheep of Denmark during the Bronze period had extra-
ordinarily slender limbs, and the horse was smaller than our
present animal.^ No doubt in most of these cases the new
and larger breeds were introduced from foreign lands by the
immigration of new hordes of men. But it is not probable that
each larger breed, which in the course of time has supplanted
a previous and smaller breed, was the descendant of a distinct
and larger species ; it is far more probable that the domestic
races of our various animals were gradually improved in
different parts of the great Europajo- Asiatic continent, and
thence spread to other countries. This fact of the gradual
increase in size of our domestic animals is all the more
striking as certain wild or half-wild animals, such as red-
deer, aurochs, park-cattle, and boars,^" have within nearly the
same period decreased in size.

The conditions favourable to selection by man are, — the
closest attention to every character, — long-continued per-
severance,— facility in matching or separating animals, — and
especially a large number being kept, so that the inferior
individuals may be freely rejected or destroyed, and the better
ones preserved. AVhen many are kept there will also be a
greater chance of the occurrence of well-marked deviations of
tstructure. Length of time is all-important ; for as each cha-
racter, in order to become strongly pronounced, has to be
augumented by the selection of successive variations of the
same kind, this can be effected only during a long series of
generations. Length of time will, also, allow any new
feature to become fixed by the continued rejection of those

^ Morlot, * Soc. Vaud. des Scien. ^" Riitimeyer, ' Die Fauna der

Nat.' Mars, 1860, p. 298. Pfahlbauten/ 1861, s. 30.

424 CONCLUDING KEMARKS. Chap. XXVUI.

individuals which revert or vary, and by the preservation of
those which still inherit the new character. Hence, althoug-h
some few animals have varied rapidly in certain respects
under new conditions of life, as dogs in India and sheep in
the West Indies, yet all the animals and plants which have
produced strongly marked races were domesticated at an
extremely remote epoch, often before the dawn of histor3^ As
a consequence of this, no record has been preserved of the
origin of our chief domestic breeds. Even at the present day
new strains or sub-breeds are formed so slowly that their first
appearance passes unnoticed. A man attends to some par-
ticular character, or merely matches his animals with unusual
care, and after a time a slight difference is perceived by his
neighbours ; — the difference goes on being augmented by un-
conscious and methodical selection, until at last a new sub-
breed is formed, receives a local name, and spreads ; but by
this time its history is almost forgotten. When the new
breed has spread widely, it gives rise to new strains and sub-
breeds, and the best of these succeed and spread, supplanting
other and older breeds ; and so always onwards in the march
of improvement.

When a well-marked breed has once been established, if not
supplanted b}^ still further improved sub-breeds, and if not
exposed to greatly changed conditions of life inducing further
variability or reversion to long-lost characters, it may ap-
parently last for an enormous period. We may infer that this
is the case from the high antiquity of certain races ; but some
caution is necessary on this head, for the same variation may
appear independently after long intervals of time, or in distant
places. W^e may safely assume that this has occurred with the
turnspit-dog, of which one is figured on the ancient Egyptian
monuments — with the solid-hoofed swine ^^ mentioned by
Aristotle — with five-toed fowls described by Columella — and
certainly with the nectarine. The dogs represented on the
Egyptian monuments, about 2000 B.C., show us that some of
the chief breeds then existed, but it is extremely doubtful
whether any are identically the same with our present breeds.
A great mastiff sculptured on an Assyrian tomb, 640 B.C., is

" Godron, ' De I'Esp^ce,' torn, i., 1859, p. 368.

Chat. XXVIII. CONCLUDING EEMARKS. 425

said to be the same with the dog still imported from Thibet
into the same region. The true greyhound existed during the
Roman classical period. Coming down to a later period, we
have seen that, though most of the chief breeds of the pigeon
existed between two and three centuries ago, they have not
all retained exactly the same character to the present day ;
but this has occurred in certain cases in which no imjirove-
ment was desired, for instance, in the case of the Spot and
Indian ground-tumbler.

De Candolle ^'^ has fully discussed the antiquity of various
races of plants ; he states that the black seeded poppy was
known in the time of Homer, the white-seeded sesamum by
the ancient Egyptians, and almonds with sweet and bitter
kernels by the Hebrews ; but it does not seem improbable
that some of these varieties may have been lost and reap-
peared. One variety of barley and apparently one of wheat,
both of which were cultivated at an immensely remote period
by the Lake-inhabitants of Switzerland, still exist. It is
said ^^ that " specimens of a small variety of gourd which is
" still common in the market of Lima were exhumed from an
" ancient cemetery in Peru," De Candolle remarks that, in
the books and drawings of the sixteenth century, the principal
races of the cabbage, turnip, and gourd can be recognised :
this might have been expected at so late a period, but
whether any of these plants are absolutely identical with
our present sub-varieties is not certain. It is, however, said
that the Brussels sprout, a variety which in some places is
liable to degeneration, has remained genuine for more than
four centuries in the district where it is believed to have
originated.^*

In accordance with the views maintained by me in this
work and elsewhere, not onlj^ the various domestic races, but
the most distinct genera and orders within the same great
class — for instance, mammals, birds, reptiles, and fishes — are

*2 'Geographie Botan.,' 1855, p, *■* 'Journal of a Horticultural

989. Tour,' by a Deputation of the Cale-

'^ Pickering, ' Races of Man,' donian Hist. Soc, 1823, p. 293.
1850, p. 318.

i26 CONCLUDING KEMARKS. Chap. XXVUI.

all the descendants of one common progenitor, and we must
admit that tlie whole vast amount of difference between
these forms has primarily arisen from simple variability.
To consider the subject under this point of view is enough to
strike one dumb with amazement. But our amazement ought
to be lessened when we reflect that beings almost infinite in
number, during an almost infinite lapse of time, have often
had their whole organisation rendered in some degree
plastic, and that each slight modification of structure which
was in any way beneficial under excessively complex con-
ditions of life has been preserved, whilst each which was in
any way injurious has been rigorously destroj^ed. And the
lonfr-continued accumulation of beneficial variations will
infallibly have led to structures as diversified, as beautifully
adapted for various purposes and as excellently co-ordinated,
as we see in the animals and plants around us. Hence I
have spoken of selection as the paramount power, whether
applied by man to the formation of domestic breeds, or by
nature to the production of species. I may recur to the
metaphor given in a former chapter : if an architect were
to rear a noble and commodious edifice, without the use of cut
stone, by selecting from the fragments at the base of a preci-
pice wedge-formed stones for his arches, elongated stones for
his lintels, and flat stones for his roof, we should admire his
skill and regard him as the paramount power. Kow, the
fragments of stone, though indispensable to the architect,
bear to the edifice built by him the same relation which the
fluctuating variations of organic beings bear to the varied
and admirable structures ultimately acquired by their modified
descendants.

Some authors have declared that natural selection explains
nothing, unless the precise cause of each slight individual
difference be made clear. If it were explained to a savage
utterly ignorant of the art of building, how the edifice had
been raised stone upon stone, and why wedge-formed frag-
ments were used for the arches, flat stones for the roof, &c. ; and
if the use of each part and of the whole building were pointed
out, it would be unreasonable if he declared that nothing had
been made clear to him, because the precise cause of the shape

Chap. XXVIII. CONCLUDING REMARKS. 427

of each, fragment could not be told. But this is a nearly
parallel case with the objection that selection explains nothing,
because we know not the cause of each individual difierence in
the structure of each being.

The shape of the fragments of stone at the base of our pre-
cipice may be called accidental, but this is not strictly correct ;
for the shape of each depends on a long sequence of events, all
obeying natural laws ; on the nature of the rock, on the lines
of deposition or cleavage, on the form of the mountain, which
depends on its upheaval and subsequent denudation, and lastly
on the storm or earthquake which throws down the fragments.
But in regard to the use to which the fragments may be put,
their shape may be strictly said to be accidental. And here
we are led to face a great difficulty, in alluding to which I am
aware that I am travelling beyond my proper province. An
omniscient Creator must have foreseen every consequence
which results from the laws imposed by Him. But can it be
reasonably maintained that the Creator intentionally ordered,
if we use the words in any ordinary sense, that certain frag-
ments of rock should assume certain shapes so that the builder
might erect his edifice ? If the various laws which have
determined the shape of each fragment were not predeter-
mined for the builder's sake, can it be maintained Mdth any
greater probability that He specially ordained for the sake of
the breeder each of the innumerable variations in our do-
mestic animals and plants ; — many of these variations being
of no service to man, and not beneficial, far more often inju-
rious, to the creatures themselves ? Did He ordain that the
crop and tail-feathers of the pigeon should vary in order that
the fancier might make his grotesque pouter and fantail
breeds? Did He cause the frame and mental qualities of the
dog to vary in order that a breed might be formed of indomi-
table ferocity, with jaws fitted to pin down the bull for man's
brutal sport ? But if we give up the principle in one case, —
if we do not admit that the variations of the primeval dog
were intentionally guided in order that the grej'hound, for
instance, that perfect image of symmetry and vigour, might
be formed,— no shadow of reason can be assigned for the
belief that variations, alike in nature and the result of the

428 CONCLUbING REMARKS. Chap. XXVIII.

same general laws, wliicli have been the groundwork through
natural selection of the formation of the most perfectly
adapted animals in the world, man included, were inten-
tionally and specially guided. However much we may wi«h
it, we can hardly follow Professor Asa Gray in his belief " that
*' variation has been led along certain beneficial lines," like a
stream " along definite and useful lines of irrigation." If we
assume that each particular variation was from the beginning
of all time preordained, then that plasticity of organisation,
which leads to many injurious deviations of structure, as well
as the redundant power of reproduction which inevitably leads
to a struggle for existence, and, as a consequence, to the
natural selection or survival of the fittest, must appear to us
superfluous laws of nature. On the other hand, an omni-
potent and omniscient Creator ordains everything and fore-
sees everything. Thus we are brought face to face with
a difficulty as insoluble as is that of free will and predesti-
nation.

INDEX.

-»o*-

ABBAS.

ALEFIELD.

Abbas Pacha, a fancier of fantailed pi-
geons, i. 216.

Abbey, Mr., on grafting, ii. 128, 129 ;
on mignonette, ii. 223.

Abbott, Mr. Keith, on the Persian
tumbler pigeon, i. 156.

Abbreviation of the facial bones, i.
76.

Abortion of organs, ii. 306-310, 392.

Absorption of minority in crossed
races, ii. 65-67, 158.

Abutilon, graft hybridisation of, i.
418.

Acclimatisation, ii. 295-305 ; of
maize, i. 34-1.

Acerbi, Oil the fertility of domestic
animals in Lapland, ii. 90.

Achatinella, ii. 28.

Achillea millefolium, bud variation in, i.
440.

Aconitum napellus, roots of, innocuous
in cold climates, ii. 264.

Acorus calamus, sterility of, ii. 154.

Acosta, on fowls in South America at
its discovery, i. 249.

Acropera, number of seeds in, ii. 373.

Adam, M., origin of Cytisus adami, i.
416.

Adam, W., on consanguineous mar-
riages, ii. 103.

Adams, on hereditary diseases, i. 451.

Advancement in scale of organisation,
i. 8.

JEgilops triticoides, observations of
Fabre and Godron on, i. 330 ; in-
creasing fertility of hybrids of, \t-ith
wheat, ii. 88.

^senilis pavia, tendency of, to become
double, ii. 152.

JEthusa cynapium, ii. 331.

AJ'FiNiT\, sexual elective, ii. 163.

Africa, white bull from, i. 95 ; feral
cattle in, i, 89 ; food-plants of savages
of, i. 325 ; South, diversity of breeds
of cattle in, i. 84 ; West, change in
fleece of sheep in, i. 102.

Agave vivipara, seeding of, in poor soil,
ii. 152.

Age, changes in trees, dependent on, i.
413.

, as bearing on pangenesis, li. 384.

Agouti, fertility of, in captivity, ii.
135.

Agriculture, antiquity of, ii. 230.

Agrostis, seeds of, used as food, i. 326.

Aguara, i. 27.

AiNSWORTH, Mr., on the change in
the hair of animals at Angora, ii.
268.

Akbar Khan, his fondness for pigeons,
i. 215; ii. 188.

Alauda arvensis, ii. 137.

Albin, on " Golden Hamburgh " fowls,
i. 259 ; figure of the hook-billed
duck, i. 291.

Albinism, i. 114, 460.

Albino, negro, attacked by insects, iL
214.

Albinoes, heredity of, i. 454.

Albinus, thickness of the epidermis on
the palms of the hands in man, ii.
287.

Alco, i. 32, ii. 80.

Aldrovandi, on rabbits, i. 108 ; de-
scription of the nun pigeon, i. 164;
on the fondness of the Dutch for
pigeons in the seventeenth century,
i. 215; notice of several varieties of
pigeons, i. 217-220; on the breeds of
fowls, i. 259 ; on the origin of the
domestic duck, i. 292.

Alefield, Dr., on the varieties of peas

430

ALEXANDER.

INDEX.

ANTIGUA.

and their specific unity, i. 345 ; on
the varieties of beans, i. 349.

Alexander the Great, his selection of
Indian cattle, ii. 186.

Alg^, retrogressive metamorphosis in,
ii. 354; division of zoospores of, ii.
372.

Allen, J., birds in United States, ii.
271.

4llen, W., on feral fowls, i. 249, ii.
7.

Allman, Professor, on a monstrous
Saxifraga geum, ii. 150 ; on the Hy-
droida, ii. 354, 364.

Almond, i. 357 ; antiquity :<", ii. 425 ;
bitter, not eaten by mice, ii. 218.

Alniis qlutlnosa, and incana, hj^brids of,
ii. 111.

Alpaca, selection of, ii. 192.

Althcea rosea, i. 402, ii. 85.

Amari/Uis, ii. 120.

Amaryllis vittata, eifect of foreign pollen
on, i. 431.

Amaurosis, hereditary, i. 453.

Ainblystoma lurida, ii. 358.

America, limits within which no use-
ful plants have been furnished by, i.
327 ; colours of feral horses in, i. 62-
64; North, native cultivated plants
of, i. 329 ; skin of feral pig from, i.
80 ; South, variations in cattle of, i.
92, 95.

Ammon, on the persistency of colour in
horses, i. 465.

Amygdalus persica, i. 357-365, 398.

Anagallis arvensis, ii. 173.

Analogous variation, i. 442, ii. 341-
345 ; in horses, i. 58 ; in the horse
and ass, i. 67 ; in fowls, i. 255-257.

Anas boschas, i. 291, ii. 14 ; skull of,
figured, i. 297.

"Ancon" sheep of Massachusetts, i.
104, ii. 70.

Andalusian fowls, i. 238.

Andalusian rabbits, i. 109.

Anderson, J., on the origin of British
sheep, i. 98 ; on the selection of
qualities in cattle, ii. 180; on a one-
eared breed of rabbits, i. 112 ; on the
inheritance of characters from a one-
eared rabbit, and three-legged bitch,
i. 456 ; on the persistency of varieties
of peas, i. 349 ; on the production of
early peas by selection, ii. 185; on

the varieties of the ])otato, i. 350,
351 ; on crossing varieties of the
melon, i. 430 ; on reversion in the
barberry, i. 410.

Anderson, Mr., on the reproduction of
the weeping ash by seed, i. 462 ; on
the cultivation of the tree paeony in
China, ii. 189.

Andersson, Mr., on the Damara, Bechu-
aua, and Nam aqua cattle, i. 91 ; on
the cows of the Damaras, ii. 290 ;
selection practised by the Damaras
and Namaquas, ii. 192; on the use of
grass-seeds ami the roots of reeds as
food in South Africa, i. 326.

Anemone coronaria, doubled by selection,
ii. 185.

Angina pectoris, hereditary, occurring
at a certain age, ii. 55.

Anglesea, cattle of, i. 84.

Angola sheep, i. 98.

Angora, change in hair of animals at,
ii. 268; cats of, i. 47, 49 ; rabbits of,
i. no, 127.

Animals, domestication of, facilitated
by fearlessness of man, i. 20 ; refusal
of wild, to breed in captivity, ii. 131 ;
compound, individual peculiarities of,
reproduced by budding, i. 398 ; varia-
tion by selection in useful qualities
of, ii. 205.

Annual plants, rarity of bud-variation
in, i. 440.

Anomalies in the osteology of the

horse, i. 51

of

pigs,

■8; of

Anomalous breeds
cattle, i. 92.

Anser albifrons, characters of, repro-
duced in domestic geese, i. 303.

Anser cB(fijptiacus, i. 296, ii. 44.

Anser canadensis, ii. 1-10.

Anser ferv^, the original of the domes-
tic goose, i. 302 ; fertility of cross of,
with domestic goose, i. 303.

Anson, on feral fowls in the Ladrones,
i. 249.

Antagonism between growth and re-
production, ii. 379.

Anthemis no'iUis, bud-variation in
flowers of, i. 404 ; becomes single in
poor soil, ii. 151.

Anthers, contabescence of, ii. 149.

.ANTIGUA, cats of, i. 48 ; changed fleecfl
of sheep in, i. 102.

ANTIRRHINUM.

INDEX.

AUSTRALIA.

431

Antirrhinum majus, peloric, i. 389, ii.
33, 46, 150; double-flowered, ii. 151 ;
bud-variation in, i. 407.

Ants, individual recognition of, ii. 238.

Aphides, attacking pear-trees, ii. 217;
development of, ii. 361-362.

Apoplexy, hereditary, occuri'iag at a
certain age, ii. 54.

Apple, i. 369-372; fruit of, in Swiss
lake-dwellings, i. 335 ; I'endered fasti-
gate by heat in India, i. 385 ; bud-
variation in the, i. 401 ; with dimi-
diate fruit, i. 425, 426 ; with two
kinds of fruit on the same branch, i.
425 ; artificial fecundation of, i. 432 ;
St. Valery, i. 432, ii. 150 ; reversion
in seedlings of, ii. 4 ; crossing of
varieties of, ii. 110; growth of the,
in Ceylon, ii. 266 ; winter majetin,
not attacked by coccus, ii. 217 ;
flower-buds of, attacked by bull-
finches, ibid. ; American, change of,
when grown in England, ii. 264.

Apricot, i. 365, 366 ; glands on the
leaves of, ii. 217 ; analogous variation
in the, ii. 341.

Aquila ftisca, copulating in captivity,
ii. 137.

Aquilegia vulgaris, i. 389 ; ii. 323.

Arab boarhound, described by Har-
court, i. 17.

Arabis hlepharophylla and A. soyeri,
effects of crossing, i. 431.

Aralia trifoliata, bud-variation in leaves
of, i. 408.

Araucarias, young, variable resistance
of, to frost, ii. 299. ,

Archangel pigeon, ii. 226.

Arctic regions, variability of plants
and shells of, ii. 244.

Aria vestita, grafted on thorns, i. 413.

Aristophanes, fowls mentioned by, i.
258.

Aristotle, on solid-hoofed pigs, i. 78 ;
domestic duck unknown to, i. 292 ;
on the assumption of male characters
by old hens, ii. 26.

Arni, domestication of the, i. 86.

Arnold, Mr., experiments of pollen on
the maize, i. 431.

Arrests of development, ii. 306-310.

Arteries, increase of anastomosing
branches of, when tied, ii. 290.

Aru Islands, wild pig of, i. 70

Arum, Polynesian varieties of, ii. 243.

Ascaris, number of eggs of, ii. 373.

Ash, varieties of the, i. 384 ; weeping,
i. 385 ; simple-leaved, ibid. ; bud-
variation in, i. 408 ; effects of graft
upon the stock in the, i. 418 ; pro-
duction of the blotched Breadalbaue,
ibid. ; weeping, capricious reproduc-
tion of, by seed, i. 462.

A sinus burchellii, i. 67.

Asinus Jiemionus, ii. 17.

Asinus indicus, ii. 17, 22.

Asinus quagga, i. 67,

Asinus tiBniojms, ii. 16 ; the original of
the domestic ass, i. 65.

Asparagus, increased fertility of culti-
vated, ii. 91.

Ass, early domestication of the, 1. 65 ;
bi-eeds of, ibid. ; small size of, in
India, ihid. ; stripes of, i. QQ, 67 ; ii.
343 ; dislike of, to cross water, i. 190 ;
reversion in, ii. 16, 17, 22 ; hybrid
of the, with mare and zebra, ii. 16 ;
jirepotency of the, over the horse, ii.
43; crossed with wild ass, ii. 190;
variation and selection of the, ii. 222.

Assyrian sculpture of a mastiif, i. 17.

Asters, i. 463, ii. 307.

Asthma, hereditary, i. 452, ii. 55.

Atavism. See Reversion.

Athelstan, his care of horses, ii. 187.

Atkinson, Mr., on the sterility of the
Tarroo sillcmoth in confinement, ii.
141.

Aubergine, ii. 68.

Audubon, on feral hybrid ducks, i.
200, ii. 20 ; on the domestication of
wild ducks on the Mississippi, i. 292 ;
on the wild cock turkey visiting
domestic hens, i. 308 ; fertility of
Fringilla ciris in captivity, ii. 137 ;
fertility of Columba migratoria and
leucocephala in captivity, ii. 139 ;
breeding of Anser canadensis in cap-
tivity, ii. 140.

Audubon and Bachman, on the change
of coat m Ovis montana, i. 103 ; ste-
rility of Sciurus cinerea in confine-
ment, ii. 135.

Auricula, effect of seasonal conditions
on the, ii. 263 ; blooming of, ii. 339.

Australia, no generally useful plants
derived from, i. 328 ; useful plants
of, enumerated by Hooker, i. 328.

i32

AUSTRIA.

INDEX.

BATES.

Austria, heredity of character in em-
perors of, ii. 40.

AuTENRiETH, on persistency of colour
in horses, i. 465.

AvA, horses of, i. 56.

Aiiena fatua, cultivability of, i. 330.

* Ayeen Akbery,' pigeons mentioned in
the, i. 158, 163, 194, 215, 217, 218.

Ayres, W. p., on bud-Tariation in
pelargoniums, i. 403.

Azalea indica, bud-variation in, i. 402.

AzARA, on the feral dogs of La Plata,
i. 28 ; on the crossing of domestic
with wild cats in Paras^uay, i. 47 ;
on hornlike processes in horses, i. 52 ;
on curled hair in horses, i. 56, ii.
189, 318; on the colours of feral
horses, i. 64, ii. 246 ; on the cattle of
Paraguay and La Plata, i. 86, 89, 92,
ii. 246; on a hornless bull, ii. 190,
on the increase of cattle in South
America, ii. 98 ; on the growth of
horns in the hornless cattle of Cor-
rientes, ii. 13 ; on the " Niata " cattle,
i. 94 ; on naked quadrupeds, ii. 268 ;
on a race of black-skinned fowls in
South America, i. 243, ii. 194; on
a variety of maize, i. 339.

Babington, C. C, on the origin of the
plum, i. 367 ; British species of the
genus Jiosa, i. 390 ; distinctness of
Viola lutea and tricolor, i. 392.

Bachmann, Mr., on the turkey, ii. 250.
See also Audubon.

Badger, breeding in confinement, ii.
134.

" Bagadotten-Taube," i. 148.

Baily, Mr., on the effect of selection
on fowls, ii. 182 ; on Dorking fowls,
ii. 224.

Baird, S., on the origin of the turkey,
i. 308.

Baker, Mr., on heredity in the horse,
i. 455 ; on the degeneration of the
horse by neglect, ii. 225 ; orders of
Henrys VII. and VIII. for the
destruction of undersized mares, ii.
188.

Bakewell, change in the sheep effected
by, ii. 182.

Balancement, ii. 335, 336 ; of growth,
law of, 335.

Baldhead (pigeon), i. 158.

Baldness, in man, inherited, ii. 31 9 ^
with deficiency in teeth, ii. 319, 320.

Ballance, Mr., on the effects of in-
terbreeding on fowls, ii. 105 ; on
variation in the eggs of fowls, i. 261.

Ballota nigra, transmission of variegated
leaves in, i. 409.

Bamboo, varieties of the, ii. 243.

Banana, variation of the, i. 396, ii.
243 ; bud-variation in the, i. 401 ;
sterility of the, ii. 256.

Bantam fowls, i. 241 ; Sebright, origin
of, ii. 74; sterility of, ii. 79.

Barb (pigeon), i. 151, 153, 220, ii.
212; figure of, i. 152; figure of
lower jaw of, i. 173.

Barbs, of wheat, i. 331.

Barberry, dark or red-leaved variety',
i. 385, 462 ; reversion in suckers of
seedless variety, i. 410.

Barbut, J., on the dogs of Guinea, i.
26 ; on the domestic pigeons in
Guinea, i. 195; fowls not native in
Guinea, i. 249.

Barking, acquisition of the habit of,
by various dogs, i. 28.

Barley, wild, i. 330; of the lake-
dwellings, i. 335-337; ancient variety
of, ii. 425.

Barnes, Mr., production of early peas
by selection, ii. 185.

Barnet, Mr., on the intercrossing of
strawberries, i. 373 ; dioeciousness of
the hautbois strawberry, i, 375 ; on
the Scarlet American strawberry, ii.
184.

Barth, Dr., use of grass-seeds as food
in Central Africa, i. 325.

Bartlett, a. D., on the origin of
" Himalayan " rabbits by intercross-
ing, i. 113; on the feral rabbits of
Porto Santo, i. 119 ; on geese with
revei'sed feathers on the head and
neck, i. 303 ; on the young of the
black-shouldered peacock, i. 306 ; on
a variety of the turkey, i. 309 ; size
of hybrids, ii. 112; on the breeding
of the Felidse in captivity, ii. 133;
so-called hybrids, ii. 316.

Bartram, on the black wolf-dog of
Florida, i. 23.

Bates, H. W., refusal of wild animals
to breed in captivity, ii. 132, 135 ;
sterility of American monkeys in

BATRACHIA.

INDEX.

BENNETT.

433

captivity, li. 136 ; sterility of tamed
guans, ii. l':59.

Batrachia, regeneration of lost parts
in, ii. 358.

Beach, raised, in Peru, containing heads
of maize, i. 338.

Beak, variability of, in fowls, i. 271 ;
individual diflerences of, in pigeons,
i. 168 ; correlation of, with the feet
in pigeons, i. 180-184-.

Beale, Lionel, on the contents of cells,
ii. 372 ; on the multiplication of in-
fectious atoms, ii. 372.

Beans, i. 349 ; of Swiss lake-dwellings,
i. 337; varieties of, produced by
selection, ii. 203 ; French and scarlet,
variable resistance of, to frost, ii.
299, 305 ; superiority of native seed
of, ii. 305 ; a symmetrical variation
of scarlet, ii. 349 ; experiments on
kidney, i. 314 ; with monstrous
stipules and abortive leaflets, ii.
335.

Beard pigeon, i. 158.

Beaks, breeding in captivity, ii. 134.

Beasley, J., reversion in crossed cattle,
ii. 15.

Beaton, D., effect of soil upon straw-
berries, i. 376 ; on varieties of pelar-
gonium, i, 388, ii. 263, 301 ; bud-
variation in Gladiolus colvillii, i. 407 ;
cross between Scotch kail and cab-
bage, ii. 76 ; hybrid gladiolus, ii. 121 ;
constant occurrence of new forms
among seedlings, ii. 221 ; on the
doubling of the Compositaj, ii. 307.

Bechuana cattle, i. 91.

Bechstein, on the burrowing of wolves,
i. 28 ; Spitz Dog, i. 32 ; origin of
the Newfoundland dog, i. 44 ; crossing
of domestic and wild swine, i. 69 ; on
the Jacobin pigeon, i. 162, 219 ;
notice of swallow-pigeons, i. 164 ; on
a fork-tailed pigeon, i. 164 ; varia-
tions in the colour of the croup in
pigeons, i. 193; on the German dove-
cot pigeon, i. 195 ; fertility of mon-
grel-pigeons, i. 202 ; on hybrid
turtle-doves, i. 203 ; on crossing the
pigeon with Colamha cenas, C. palum-
bus, Turtur risoria, and T. vulgaris, i.
202 ; development of spurs in the
silk-hen, i. 269 ; on Polish fowls, i.
269, 276 ; on crested birds, i. 269 ;

on the canary-bird, 1. 311, 465, ii.
145 ; German superstition about the
turkey, i. 309 ; occurrence of horns
in hornless breeds of sheep, ii. 3 ;
hybrids of the horse and ass, ii. 43 ;
crosses of tailless fowls, ii. 70 ; diffi-
culty of pairing dove-cot and fancy
pigeons, ii. 82 ; fertility of tame
ferrets and rabbits, ii. 90 ; fertility
of wild sow, ibid. ; difficulty of breed-
ing caged birds, ii. 137 ; comparative
fertility of PsjYtocMS erithacusm cap-
tivity, ii. 138 ; on changes of plumage
in captivity, ii. 141 ; liability of
light-coloured cattle to the attacks
of flies, ii. 214; want of exercise a
cause of variability, ii. 244 ; effect of
privation of light upon the plumage
of birds, ii. 270 ; on a sub-variety of
the monk-pigeon, ii. 343.

Beck, Mr., constitutional differences in
pelargoniums, i. 388.

Beckmann, on changes in the odours
of plants, ii. 264.

Beddoe, Dr., correlation of complexion
with consumption, ii. 329.

Bee, persistency of character of, ii.
222, 241 ; intercrossing, ii. 107 ;
conveyance of pollen of peas by, i.
348.

Bee Ophrys, self-fertilisation of, ii.
69.

Beech, dark-leaA-ed, i. 385, 462 ; fern-
leaved, reversion of, i. 408 ; weeping,
non-production of, by seed, i. 462.

Beechey, horses of Loochoo Islands, i.
56.

Beet, i. 344 ; increase of sugar in, bj
selection, ii. 185.

Begonia frigida, singular variety of, i,
389 ; sterility of, ii. 150.

Belgian rabbit, i. 110.

Bell, T., statement that white cattle
have coloured ears, i. 89.

Bell, W., bud-variatiou in Paritium
tricuspis, i. 402.

Bellingeri, observations on gestation
in the dog, i, 31 ; ou the fertility of
dogs and cats, ii. 90.

Belon, on high-flying pigeons in Pa-
phlagonia, i. 219; varieties of the
goose, i. 305.

Bengcjela, cattle of, i. 92.

Bennett, Dr. G., pigs of the Pacific

434

BENNETT.

INDEX.

BLYTH.

Islands, i. 73, ii. 64; dogs of the
Pacific Islands, ibid.; varieties of cul-
tivated plants in Tahiti, ii. 243.

Bennett, Mr., on the fallow deer, ii.
81.

Bentham, G., nmnber and origin of
cultivated plants, i. 323 ; on Phaseo-
lus, i. 350 ; cereals all cultivated
varieties, i. 330 ; species of the
orange group, i. 355 ; distinctions
of almond and peach, i. 358 ; Bri-
tish species of Rosa, i. 390 ; identity
of Viola lutea and tricolor, i. 392.

Berlieris vulgaris, i. 410, i. 462.

Bcrheris wallichii, indifference of, to cli-
mate, ii. 148^

Berjeau, on the history of the dog, i.
17, 18.

Berkeley, G. F., production of hen-
cocks in a strain of game-fowls, i.
2i^5.

Berkeley, M. J., crossing of varieties
of the pea, i. 428 ; effect of foreign
pollen on grapes, i. 430 ; on hybrid
plants, ii. 112; analogy between
pollen of highly-cultivated plants
and hybrids, ii. 256 ; on Hungarian
kidney^beans, ii. 265 ; failure of In-
dian wheat in England, ii. 297.

Bernard, inheritance of disease in the
horse, i. 455.

Bernard, C, independence of the or-
gans of the body, ii. 364 ; special
affinities of the tissues, ii. 375.

Bernhardi, varieties of plants with
laciniated leaves, ii. 341.

Bernicla antarctica, i. 303.

Bertero, on feral pigeons in Juan Fer-
nandez, i. 200.

Betula alba, i. 461.

Bewick, on the British wild cattle, i.
87.

BiANCONi, Prof., on the skulls of dogs,
i. 35.

Bible, reference to breeding studs of
horses in, i. 57 ; references to domes-
tic pigeons in the, i. 214 ; indications
of selection of sheep in the, ii. 186 ;
notice of mules in the, ibid.

Bidwell, Mr., on self-impotence in
Amaryllis, ii, 120.

Bignonia, self-sterility of, ii. 117.

Birch, weeping, i. 413, 461.

Birch, Dr. S., on the ancient domesti-

cation of the pigeon in Egypt, i.
214; notice of bantam fowls in a
Japanese encyclopfedia, i. 241, 259.

Birch, Wyuley, on silver-grey rabbits,
i. 113, 114.

Birds, sterility caused in, by change of
conditions, ii. 136-141.

Bladder-nut, tendency of the, to be-
come double, ii. 152.

Blaine, Mr., on wry-legged terriers,
ii. 232.

Blainville, origin and history of the
dog, i. 15-17 ; variations in the
number of teeth in dogs, i. 36 ;
variations in the number of toes in
dogs, i. 37 ; on mummies of cats, i.
45 ; on the osteology of solid-hoofed
pigs, i. 78 ; on feral Patagonian and
N. American pigs, i. 80.

" Blass-Taube," i. 163.

Bleeding, hereditary, i. 452 ; sexual
limitation of excessive, ii. 48.

Blending of crossed races, time occu-
pied by the, ii. 64.

Blindness, hereditary, i. 454; at a
certain age, ii. 54 ; associated with
colour of hair, ii. 322.

Bloodhounds, degeneration of, caused
by interbreeding, ii. 100.

Blumenbach, on the protuberance of
the skull in Polish fowls, i. 269 ; on
the effect of circumcision, i. 467 ;
inheritance of a crooked finger, i.
469 ; on badger-dogs and other
varieties of the dog, ii. 205 ; on
Hydra, ii. 283 ; on the " nisus forma-
tivus," ii. 284.

Blyth, E., on the pariah dog, i. 25;
hybrids of dog and jackal, i. 33 ;
earlv domestication of cats in India,
i. 45 ; origin of domestic cat, i. 46 ;
crossing of domestic and wild cats,
ibid.; on Indian cats resemblmg Felis
chaus, i. 47 ; on striped Burmese
ponies, i. 61; on the stripes of the
ass, i. 65 : on Indian wild pigs, i. 69 ;
on humped cattle, i. 83 ; occurrence
of Bos frontosus in Irish crannoges,
i. 85 ; fertile crossing of zebus and
common cattle, i. 86 ; on the species
of sheep, i. 97 ; on the fat-tailed Indian
sheep, i. 99 ; origin of the goat, i
105 ; on rabbits breeding in India, i.
116 ; number of tail-feathers in fan*

BOETHIUS.

IxVDEX.

I50SMAN.

435

tails, i. 153 ; Lot. in tumbler pigeons,
i. 157 ; number of tail-feathers in
Ectopistes, i. 67 ; on Columba afflnis,
i. 192 ; pigeons roosting in trees, i.
190; on Columba leuconofa, i. 191;
on Cchimba intermedia of Strickland,
i. 193 ; variation in colour of croup
in pigeons, i. 193, 194, 206; volun-
tary domestication of rock-pigeons in
India, i. 194-; feral pigeons on the
Hudson, i. 200 ; occurrence of sub-
species of pigeons, i. 214; notice of
pigeon-fanciers in Delhi, &c,, i. 215 ;
hybrids of G alius sonneratii and the
domestic hen, i. 245 ; supposed hy-
bridity of Gallus temminckii, i. 246 ;
variations and domestication of Gal-
lus bankioa, i. 247, 248; crossing of
wild and tame fowls in Burmah, i.
248 : restricted range of the larger
gallinaceous birds, i, 249; feral fowls
in the Nicobar Islands, i. 249 ; black-
skinned fowls occurring near Cal-
cutta, i. 269 ; weight of Gallus han-
kiva, i. 286 ; degeneration of the
turljey in India, i. 310, ii. 267; on
the colour of gold-fish, i. 312 ; re-
version from a cross, ii. 15 ; on the
Ghor-Khur (^Asinus indicus'), ii. 17 ;
on Asinus hemionus, ii. 17 ; number
of eggs of Gallus bankiva, ii. 90 ; on
the breeding of birds in captivity, ii. *
140 ; co-existence of large and small
breeds in the same country, ii. 268 ;
on the drooping ears of the elephant,
ii. 291 ; homology of leg and wing
feathers, ii. 315.

BOETHius on Scotch wild cattle, i. 88.

BoiTARD and Corbie, on the breeds of
pigeons, i. 138; Lille pouter pigeon,
i. 145 ; notice of a gliding pigeon, i.
164 ; variety of the pouter pigeon, i.
170 ; dove-cot pigeon, i. 194 ; cross-
ing pigeons, i. 202, ii. 75, 107;
sterility of hybrids of turtle-doves, i.
203 ; reversion of crossed pigeons, i.
207, ii. 14 ; on the fantail, i. 218, ii.
42 ; on the trumpeter, ii. 42 ; pre-
potency of transmission in silky fan-
tail, ii. 42, 44 ; secondary sexual
characters in pigeons, ii. 50 ; cross-
ing of white and coloured turtle-
doves, ii 70 ; fertility of pigeons, ii.
91.

B0MBYCID.E, wingless females of, ii.

289.
Bombijx hesperus, ii. 294.
Bombyx huttoni, i. 318.

Bombyx mori, i. 317-321.
BONAFOUS, on maize, i. 338, 339.

Bonaparte, number of species of
Columbidas, i. 139 ; number of tail-
feathers in pigeons, i. 167; size of
the feet in Columbidae, i. 183 ; on
Columba guinea, i. 192; Columba
ticrricola, rupestris and schimperiy i.
193.

Bonatea speciosa, development of ovary
of, i. 434.

BONAVIA, Dr., growth of cauliflowers
in India, ii. 301.

Boner, Mr., semi-feral sheep, ii. 5.

Bones, removal of portions of, ii. 286;
regeneration of, ii. 284 ; growth and
repair of, ii. 377.

BoNizzi, on pigeons, i. 138, 170.

Bonnet, on the salamander, ii. 357,
385; theory of reproduction, ii. 351,
370.

BORCHMEYER, experiments with the
seeds of the weeping ash, i. 462.

Borecole, i. 341.

Borelli, on Polish fowls, i. 260.

Borneo, fowls of, with tail-bands, i.
246.

BORNET, E., condition of the ovary in
hybrid Cisti. i. 415; self-impotence
of hvbrid Cisti, ii. 122.

Borrow, G., on pointers, i. 44.

BoRY DE Saint-Vincent, on gold-fish,
i. 313.

Bos, probable origin of European do-
mestic cattle from three species of,
i. 86.

Bos frontos'is, i. 85.

Bos indicus, i. 82.

Bos longifrons. i, 83, 85, 86.

Bos primigenius, i. 83-84, 86, ii. 98.

Bos sondaicus, ii. 191.

Bos taunts, i. 82.

Bos trochoceros, i. 85.

Bosc, heredity in foliage-varieties of the
elm, i. 385.

BossE, production of double flowers
from old seed, ii. 151.

Bossi, on breeding dark-coloured silk-
worms, i. 319.

Bosjian, on dogs of Guinea, i. 40.

436

BOUCHARD AT.

INDEX.

BROOMFIELD.

BOUCHARDAT, on the vine disease, i.
354.

BOUDIN, on local diseases, 'A. 266 ; re-
sistance to cold of dark-complexioned
men, ii. 329.

" BOULANS," 1. 143.

*' BOUTON d'Alep," ii. 266.

BoWEN, Prof., doubts as to the import-
ance of inheritance, i. 446.

Bowman, Mr., hereditary peculiarities
in the human eye, i. 452-454 ; here-
ditary cataract, ii. 56.

Brace, Mr., on Hungarian cattle, i. 84.

Brachycome iberidifolia, ii. 249.

Bracts, unusual development of, in
gooseberries, i. 377.

Bradley, Mr., effect of grafts upon the
stock in the ash, i. 418; etlect of
foreign pollen upon apples, i. 432 ;
on change of soil, ii. 128.

"Brahma Pootras," a new breed of
fowls, i. 258.

Brain, proportion of, in hares and
rabbits, i. 130-134.

Brandt, Dr., origin of the goat, i. 105 ;
correlation of teeth and hair, ii. 321.

Brassica, varieties of, with enlarged
stems, li. 341.

Brassica asjjerifoUa, ii. 335.

Brassica napus, i. 344.

Brassica oleracea, i. 341.

Brassica rapa, i. 344, ii. 148.

Braun, a,, bud-variation in the vine,
i. 400; in the currant, ibid.; in
Mirahilis jalapa, i. 4U7 ; in Cytisus
adumi, i. 413; on reversion in the
folinge of trees, i. 408 ; spontaneous
production of Cytisus purpureo-elon-
(jatus, i. 416 ; reversion of flowers
by stripes and blotches, ii. 11; ex-
cess of nourishment a source of
variability, ii. 244.

Brazil, cattle of, i. 92.

Bread-fruit, varieties of, ii. 243 ; ste-
rility and variability of, ii. 256.

Bree, W.T., bud-variation in Geranium
pratense and Ccntaurea cyanus, i. 404 ;
by tubers in the dahlia, i. 411 ; on the
deafness of white cats with blue eyes,
ii. 322.

Breeding, high, dependent on inheri-
tance, i. 446, 447.

Breeds, domestic, persistency of, ii, 233,
423, 424 ; artificial and natural, ii.

409,410; extinction of, ii. 421 ; of
domestic cats, i. 47-49 ; of pigs pro>
duced by crossing, i. 82 ; of cattle, i.
90, 94-97 ; of goats, i. 105.

Brehm, on Columha anialios, i. 192.

Brent, B. P., number of mammse in
rabbits, i. 110 ; habits of the tiimbler
pigeon, i, 158; Laugher pigeon, i. 163;
colouring of the kite tumbler, i. 169 ;
crossing of the pigeon with Columha
cenas, i. 202 ; mongrels of the trum-
peter pigeon, ii. 42 ; close interbreed-
ing of pigeons, ii. 106 ; opinion on
Aldrovandi's fowls, i. 259 ; on stripes
in chickens, i. 262 ; on the combs of
fowls, i. 266; double-spurred Dorking

fowls, 1.

267 ; effect of crossincr on

colour of plumage in fowls, i. 270 r
incubatory instinct of mongrels be-
tween non-setting varieties of fowls,
ii. 18 ; origin of the domestic duck,
i. 291 ; fertility of the hook-billed
duck, ibid. ; occurrence of the plu-
mage of the wild duck in domestic
breeds, i. 294 ; voice of ducks, i. 295 ;
occurrence of a short upper mandible
in crosses of hook-billed and common
ducks, ibid.; reversion in ducks pro-
duced by crossing, ii. 14; variation of
the canary-bird, i. 311 ; fashion in
the canary, ii. 226 ; hybrids of canary
and finches, ii. 20.

Brickell, on raising nectarines from
seed, i. 360 ; on the horses of North
Carolina, ii. 290.

Bridges, Mr., on the dogs of Tierra del
Fuego, i. 41 ; on the selection of dogs
by the Fuegians, ii. 191.

Bridgman, W. K., reproduction of ab-
normal ferns, i. 408.

Broca, p., on the intercrossing of dogs,
i. 32, 33 ; on hybrids of hare and
rabbit, i. 109 ; on the rumpless fowl,
i. 271 ; on the character of half-
castes, ii. 21 ; degree of fertility oi
mongrels, ii. 78 ; sterility of descend-
ants of wild animals bred in cap-
tivity, ii. 143.

Broccoli, i. 341 ; rudimentary flowers
in, ii. 307 ; tenderness of, ii. 301.

Bromehead, W., doubling of the Can-
terbury Bell by selection, ii. 185.

Broomfield, Dr., sterility of the ivy
and Acorus calamus, ii. 154.

BKOJirS,

INDEX.

BUXTOX.

437

Bromus secalinus, i. 331.

Bronn, H. G., bud A'ariation in Anthe-
mis, i. 404 ; effects of cross-breeding
on the female, i. 436 ; on heredity
in a one-horned cow, i. 456 ; propa-
gation of a pendulous peach by seed,
i. 461 ; absorption of the minority in
crossed races, ii. 65 ; on the crossing
of horses, ii. 70 ; fertility of tame
rabbits and sheep, ii. 90 ; changes of
plumage in captivity, ii. 141 ; on the
dahlia, ii. 249.

Bronze period, dog of, i. 19.

Brown, C. M., prepotency of a grey-
hound, ii. 40.

Brown, G., variations in the dentition
of the horse, i. 52.

Brown-Sequard, Dr., inheritance of
artificially-produced epilepsy in the
guinea-pig, i. 468 ; inherited effects
of injuries, ibid.

Brxnswigia, ii. 121,

Brussels sprouts, i. 341, ii. 425.

Bu'a) 7na.rimus, ii. 137.

BuCKLAND, F., on oysters, ii. 270 ; num-
ber of eggs in a codfish, ii. 373.

Buckle, Mr., doubts as to the impor-
tance of inheritance, i. 446.

Buckley, Miss, carrier-pigeons roosting
in trees, i. 190.

BucKMAN, Prof., cultivation of Avena
fatua, i. 330 ; cultivation of the wild
parsnip, i. 344, ii. 185, 267 ; rever-
sion in the parsnip, ii. 4.

Buckwheat, injurious when in flower
to white pigs, ii. 331.

Bud and seed, close analogy of, i.
444.

Bud-reversion, ii. 10.

Buds, adventitious, ii. 381.

Bud-variation, i. 397-444, ii. 242,
278, 279, 281 ; contrasted with semi-
nal reproduction, i. 397 ; peculiar to
plants, i. 398 ; in the peach, i. 360,
398; in plums, i. 399 ; in the cherry,
ibid. ; in grapes, ibid. ; in the goose-
berry and currant, i. 400 ; pear and
apple, i. 401 ; and in the banana, ca-
mellia, hawthorn. Azalea indica, and
Paritlum tricuspis, i. 402 ; in the
hollyhock and pelargonium, ibid.;
in Geranium pratcnse and the chry-
santhemum, i. 404; in roses, i. 390,
404-406 ; ia sweet williams, carna-

tions, pinks, stocks, and snapdragons,
i. 406, 407 ; in wall-flowers, cycla-
men, Q^.nothera biennis, Gladiolus
colvillii, fuchsias, and Mi7xtbilis jalapay
i. 407 ; in foliage of various trees, i.
408 ; cryptogamic plants, ibid. ; by
suckers in Phlox and barberry, i. 410 ;
by tubers in the potato, ibid. ; in the
dahlia, i. 411; by bulbs in hyacinths,
Imatophyllum miniatum, and tulips,
ibid.; in Tigridia conchiflora, i. 412;
in Bemerocallis, ibid. ; doubtful cases,
i. 412-413 ; in Cytisus adami, i. 413-
416 ; summary of observations on,
437.

Buffon, on crossing the wolf and dog,
i. 32 ; increase of fertility by domes-
tication, ii. 89 ; improvement of
plants by unconscious selection, ii
200 ; theory of reproduction, ii. 370.

Bulimus, ii. 28.

Bull, apparent influence of, on ofi'-
spring, ii. 44.

Bullace, i. 366.

Bulldog, degeneration of, in India, i. 39 ;
recent modifications of, i. 44.

Bullfinch, breeding in captivity, ii.
137 ; attacking flower-buds, ii. 217.

BuLT, Ml*., on the length of pouter
pigeons, i. 218.

" BtJNDTNERSGHWEIN," i. 70.

Bunting, reed, in captivity, ii. 141.

BuRDACH, crossing of domestic and wild
animals, i. 69 ; aversion of the wild
boar to barley, ii. 293.

Burke, Mr., inheritance in the horse, i.
455.

Burlingtonia, ii. 116.

Burmah, cats of, i. 49.

Burmese ponies, striped, i. 61.

Burnes, Sir A., on the Karakool sheep,
i. 102, ii. 268 ; varieties of the vine
in Cabool, i. 353 ; hawks, trained in.
Scinde, ii. 136; pomegranates pro-
ducing seed, ii. 152.

Burr, Fearing, potato- grafting, i. 422.

Burton Constable, wild cattle at, i. 88.

" Burzel-Tauben," i. 156,

BUSSORAH carrier, i. 148.

Buteo vulgaris, copulation of, in captiv-
ity, ii. 137.

Butterflies, polymorphic, ii. 394.

Buxton, Mr., parrots breeding in Nor-
folk, ii. 138.

(

438

BUZAREINGUES.

INDEX.

CARLIER.

BUZAREINGUES, GiROU DE, inheritance
of tricks, i. 450.

Cabanis, pears grafted on the quince,
ii. 246.

Cabbage, i. 341-344 ; varieties of, i.
341 ; unity of character in flowers
and seeds of, i. 342 ; cultivated by
ancient Celts, ibid. ; classification of
varieties of, ibid. ; ready crossing of, i.
343, ii. 68, 76. 110 ; origin of, i. 343 ;
increased fertility of, when culti-
vated, ii. 91; growth of, in tropical
countries, ii. 266.

Cabool, vines of, i. 353.

Cabral, on early cultivation in Brazil,
i. 329.

Cactus, growth of cochineal on, in
India, ii. 265.

C-flsSAR, Bos primigenius wild in Europe
in the time of, i. 84 ; notice of fowls
in Britain, i. 258 ; notice of the im-
portation of horses by the Celts, ii.
187.

Caffre fowls, i. 241.

Caffres, ditlerent kinds of cattle pos-
sessed by the, i. 91.

" Cagias," a breed of sheep, i. 99.

Cairina rnoschata, i. 191.

Calceolarias, i. 388; ii. 129 ; effects
of seasonal conditions on, ii. 263 ;
peloric flowers in, ii. 338.

Caldwell, J., sporting of sugar-cane,
i. 410.

" Calongos," a Columbian breed of
cattle, i. 92.

Calver, Mr., on a seedling peach pro-
ducing both poaches and nectarines,
i. 362.

Calyx, segments of the, converted into
carpels, ii. 387.

Camel, its dislike to crossing water, i.
190.

Camelli't, bud-variations in, i. 401 ; re-
cognition of varieties cf, ii. 238 ; va-
riety in, hardiness of, ii. 299.

Cameron, D., on the cultivation of
Alpine plants, ii. 147.

Cameronn, Baron, value of English
blood in race-horses, i. 456.

Campanula medium, ii. 185.

Canary-bird, i. 311 ; conditions of in-
heritance in, i. 465 ; hybrids of, ii.
20 ; period of perfect plumage in, ii.

53 ; diminished fertility of, ii. 145 ;
standard of perfection in, ii. 179 ;
analogous variation in, ii. 341.

Cancer, heredity of, i. 452, ii. 56.

Canfield, Dr., on horses with curled
hair, i. 58 ; on feral horses in North
America, i. 64.

Canine teeth, dcA^elopment of the, in
mares, ii. 310.

Canis alopex, i. 30.

Canis atitarcticus, i. 20.

Canis argentatus, ii. 134.

Canis aureus, i. 30.

Canis cancrivorus, domesticated and
crossed in Guiana, i. 23.

Canis cinereo-variegatus, i. 30.

Canis fulvus, i. 30.

Cams ingcc, the naked Peruvian dog,
i. 24.

Canis latrans, i. 27 ; resemblance of, to
the Hare Indian dog, i. 22 ; one of the
original stocks, i. 26.

Canis lupaster, i. 25.

Canis lupus, var. occidentalis, resem-
blance of, to North American dogs, i.
21 ; crossed with dogs, i. 23 ; one of
the original stocks, i. 26.

Cants mesomelas, i. 26, 30.

Canis primcevus, tamed by Mr. Hodgson,
i. 27.

Canis sabhar, i. 25.

Canis simensis, possible original of grey-
hounds, i. 34.

Cunis thaleb, i. 30.

Canis variegatus, i. 30.

Canning, A. S. G., the japanned pea-
cock, i. 305-307.

Canterbury Bell, doubled by selection,
ii. 185.

Cape of Good Hope, different kinds of
cattle at the, i. 91 ; no useful plants
derived from the, i. 328.

Capercailzie, breeding in captivity, ii.
139.

Capra cegagrus and C. falconeri, pro-
bable parents of domestic goat, i. 105.

Capsicum, i. 396.

Cardan, on a variety of the walnut, i.
379 ; on grafted walnuts, ii. 247.

Cardoon, ii. 7.

Carex 7-igida, local sterility of the, ii.
154.

Carlier, early selection of sheep, il
188.

CARLISLE.

INDEX.

CATTLE.

439

Carlisle, Sir A., inheritance of pecu-
liarities, i. 450, 452 ; of polydacty-
lism, i. 458.

"Carme" pigeon, i. 164.

Carnation, bud-variation in, i. 406 ;
variability of, i. 394; striped, pro-
duced by crossing red and white, i.
426 ; effect of conditions of life on the,
ii. 262.

Carnivora, general fertility of, in cap-
tivity, ii. 133.

Caroline Archipelago, cats of, i.
49.

Carp, ii. 222.

Carpels, variation of, in cultivated Cu-
curbitaceae, i. 382.

Carpenter, W.B., regeneration of bone,
ii. 284 ; number of eggs in an Ascaris,
11. Old.

Carpinus betuluSy ii. 385.

Carpophaga oceanica, ii. 408.

Cakr, Mr., elTect of changed conditions,
ii. 94.

Carrier pigeon, i. 146-149 ; English,
ibuL; figured, i. 147 ; skull figured,
i. 172; history of the, i. 221 ; Persian,
i. 148 ; Bussorah, i'jid. ; Bagadotten,
skull figured, i. 172 ; lower jaw
figured, i. 174.

Carriers, origin of radish, i. 345 ; in-
termediate form between the almond
and the peach, i. 359 ; glands of peach-
leaves, i. 364 ; bud-variation in the
vine, i. 398 ; bud-variation in the rose,
i. 406 ; inheritance in purple-leaved
trees, i. 471 ; on variation, i. 439,
441, 442 ; grafts of Aria vestita upon
thorns, i. 413 ; variability of hybrids
of Erythrina, ii. 253.

Carrot, wild, effects of cultivation on
the, i. 345 ; reversion in the, ii. 5 ;
run wild, ii. 7 ; increased fertility of
cultivated, ii. 91 ; experiments on the,
ii. 267 ; acclimatisation of the, in
India, ii. 302.

Carthaimis, abortion of the pappus in,
11. oO/.

Cartieh. cultivation of native plants
in Canada, i. 329.

CARYOPHYLLACEiE, frequency of conta-
besceoce in the, ii. 149.

Caspary, bud-variation in the moss-
rose, i. 405 ; on the ovuk-s and pollen
of Cytisus, i. 415 ; crossi.ig of Cjtisus

purpureus and C. laburnum, \. 416 ;
trifacial orange, i. 418; differently-
coloured flowers in the wild Viola
lutea, i. 440 ; sterility of the horse-
radish, ii. 154.

Castelnau, on Brazilian cattle, i. 92.

Castration, assumption of female cha-
racters caused by, ii. 26, 27.

Casuarius bennettii, ii. 140.

Ca r, domestic, i. 45-50 ; early domesti-
cation and probable origin of the, i.
45, 46 ; intercrossing of, with wild
species, i, 46, 47 ; variations of, i. 47-
49 ; feral, i. 49, ii. 6 ; anomalous, i.
50 ; polydactylism in, i. 458 ; black,
indications of stripes in young, ii. 30 ;
tortoiseshell, ii. 49; effects of crossing
in, ii. 63 ; fertility of. ii. 89 ; diflSculty
of selection in, ii. 220, 222 ; length of
intestines in, ii. 292 ; white with blue
eyes, deafness of, ii. 322 ; with tufted
ears, ii. 343.

Cataract, hereditary, i. 453, ii. 56.

Caterpillars, effect of changed food on,
ii. 270.

Catleya leopoldii, i. 431.

Catlin, G., colour of feral horses in
North America, i. 64.

Caton, Judge, wild turkey, ii. 91.

Cattle, European, their probable origin
from three original species, i. 82-85 ;
humped, or zebus, i. 82 ; inter-
crossing of, i. 86, 94, 97 ; wild, of
Chillingham, Hamilton, Chartley,
Burton Constable, and Gisburne, i.
87, ii. 97 ; colour of feral, i. 88-89,
ii. 180; British breeds of, i. 90, 91;
South African breeds of, i. 91 ; South
American breeds of, i. 92, ii. 189 ;
In lata, i. 92, 94, ii. 1 90, 193, 332 ; effects
of food and climate on, i. 94; effects
of selection on, i. 95, 96 ; Dutch-but-
tocked, 1. 452 ; hornless, production
of horns in, ii. 313 ; reversion in,
when crossed, ii. 15; wildness of
hybrid, ii. 19; short-hornod, prepo-
tency of, ii. 40 ; wild, influence of
crossing and segregation on, ii. 63 ;
crosses of, ii. 74, 82, 96 ; of Falkland
Islands, ii. 8C ; mutual fertility of all
varieties of, ii. 88 ; effects of inter-
breeding on, ii. 96, 97 ; shart-horn,
sterility of, ii. 97 ; effects of caieful
selection on, ii. 178, 18 3; naked, of

i40

CArLIF'LOWER.

INDEX.

CHINA.

Columbia, ii. 189 ; crossed with wild
banteng in Java, ii. 191 ; with re-
versed hair in Band a Oriental, ii.
190; selection of trifling characters
in, ii. 193; fashion in, ii. 195; simi-
larity of best races of, ii. 227 ; uncon-
scious selection in, ii. 198 ; effects of
natural selection on anomalous breeds
of, ii. 211, 212 ; light-coloured, at-
tacked by flies, ii. 214, 330; Jersey,
rapid improvement of, ii. 220 ; effects
of disuse of parts in, ii. 289 ; rudi-
mentary horns in, ii, 306 ; supposed
influence of humidity on the hair of,
ii. 318 ; white spots of, liable to
disease, ii. 331 ; supposed analogous
variation in, ii. 341 ; displacement
of long- horned by short-horned, ii.
421.

Cauliflower, i. 341 ; free-seeding of,
in India, ii. 301 ; rudimentary flowers
in, ii. 306.

Cavalier pigeon, ii. 75.

Cavia aperea, ii. 134.

Cay (Cebus azarce), sterility of, in con-
finement, ii. 136.

Cebiis azarce, ii. 136.

Cecidomyia, larval development of, ii.
273, 353, 363 ; and Misocimpus, i. 5.

Cedars of Lebanon and Atlas, i. 387.

Celery, turnip-rooted, i. 344 ; run wild,
ii. 7.

Cell-theory, ii. 366.

Celosia cristata, i. 389.

Celsus, on the selection of seed-corn, i.
336, ii. 187.

Celts, early cultivation of the cabbage
by the, i. 342 ; selection of cattle and
horses by the, ii. 187.

Cenchrus, seeds of a, used as food, i.
326.

Centaurea cyan'is, bud-vaj'iation in, i.
404.

Cephalopoda, spermatophores of, ii.
379.

Cerasus padus, yellow-fruited, i. 462.

Cercokptes, sterility of, in captivity, ii.
134.

Cercopithecus, breeding of a species of,
in captivity, ii. 136.

Cereals, i. 329, 330 ; of the Neolithic
period in Switzerland, i. 335 ; adapta-
tion of, to soils, ii. 295.

Cereus, ii. 11.

Cereus spcciosissimus and phyllanthus, re-
version in hybrids of, i. 425.

Cerviis canadensis, ii. 141.

Cerv'is dama, ii. 99.

Cetacea, correlation of dermal system
and teeth in the, ii. 321.

Ceylon, cats of, i. 48 ; pigeon-fancying
in, i. 216.

Chamisso, on seeding bread-fruit, ii.
152.

Channel Islands, breeds of cattle in, i.
83.

Chapman, Professor, peach-trees pro-
ducing nectarines, i. 362.

Chapuis, F., sexual peculiarities in
pigeons, i. 170 ; effect produced by
first male upon the subsequent pro-
geny of the female, i. 437 ; sterility
of the union of some pigeons, ii. 146.

Characters, fixity of, ii. 225 ; latent,
ii. 25-31, 393, 394; continued di-
vergence of, ii. 227 ; antagonistic, ii.
395.

Chardin, abundance of pigeons in Per-
sia, i. 215.

Charlemagne, orders as to the selection
of stallions, ii. 187.

Chartley, wild cattle of, i. 88.

Chate, reversion of the upper seeds in
the pods of stocks, ii. 340.

Chaundy, Mr., crossed varieties of cab-
bage, ii. 110.

Cheetah, general sterility of, in cap-
tivity, ii. 133.

Cheiranthus cheiri, i. 407.

Cherries, i. 368, 369 ; bud-variation in,
i. 399; white Tartarian, ii. 215;
variety of, with curled petals, ii. 218 ;
period of vegetation of, changed by
forcing, ii. 301.

Chevreul, on crossing fruit-trees, ii.
110.

Chickens, differences in characters of, i.
261, 262; white, liable to gapes, ii.
213, 330.

Chigoe, ii. 265.

Chile, sheep of, i. 99.

Chillingham cattle, identical with Bos
primigenius, i. 84 ; characters of, i. 87.

Chiloe, half-castes of, ii. 21.

China, cats of, with drooping ears, i.
49; horses of, i. 56; striped ponies
of, i 62; asses of, i. 66; notice of
rabbits in, by Confucius, i. 107 j breeds

CHINCHILLA.

INDEX.

COLOUR.

441

of pigeons reared in, i. 216 ; breeds
of fowls of, in fifteenth century, i.
24-3, 259.

Chinchilla, fertility of, in captivity,
ii. 135.

Chinese, selection practised by the, li.
189 ; preference of the, for hornless
rams, ii. 194 ; recognition of the value
of native breeds by the, ii. 304.

Chinese, or Himalayan rabbit, i. 112.

" Ciiivos," a breed of cattle in Paraguay,
i. 92.

Choux-raves, i. 342.

Christ, H., on the plants of the Swiss
Lake-dwellings, i. 32G, 336 ; interme-
diate forms between Finns sykcstris
and montana, i. 387.

Chrysanthemum, i. 404.

Chrysotis f estiva, ii. 269.

Cineraria, effects of selection on the,
ii. 184.

CiRCASSiA, horses of, ii. 80.

Circumcision, i. 467.

CiRRiPEDES, metagenesis in, ii. 362.

Cistus, intercrossing and hybrids of, i.
356, 459, ii. 122.

Citrons, i. 355, 356.

" Citrus aurantium fructu v <riahili" i.
357.

Citrus decumnna, i. 355.

Citrus lemonum, i. 356.

Citrus viedica, i. 355, 356.

Clapham, a., bud-variation in the
hawthorn, i. 402.

''Claquant" (pigeons), i. 145.

•'Claquers" (pigeons), i. 164.

Clark, G., on the wild dogs of Juan de
Nova, i. 28 ; on striped Burmese and
Javanese ponies, i. 61 ; breeds of
goats imported into the Mauritius, i.
105 ; variations in the mammae of
goats, i. 106 ; bilobed scrotum of
Muscat goat, ibid.

Clark, H. J., on fission and gemmation,
ii. .351.

Clarke, R. T., intercrossing of straw-
berries, i. 374.

Clarke, T., hybridisation of stoeLs, i.
429, ii. 71.

Clarkson, Mr., prize-cultivation of the
gooseberry, i. 378.

Classification, explained by the theory
<if natural selection, i. 11.

Cleft palate, inheritance of, i. 466.

Clemente, ou wild vines in Spain, i.

352.
Clermont-tonnerre, on the St. Va-

iery apple, i. 432.
Climate, effect of, upon breeds of dogs,

i. 39 ; on horses, i. 55, 56 ; on cattle,

i. 95, 96 ; on the fleece of sheep, i.

102, 103 ; on seeds of wheat, i. 333 ;

on cultivated cabbages, i. 344; adap-
tation of maize to, i. 341.
Climate and pasture, adaptation ol

breeds of sheep to, i. 100. 101.
Climate and soil, effects of, upon

strawberries, i. 375.
Cline, Mr., on the skull in horned and

hornless rams, ii. 327.
Clos, on sterility in Ranunculus ficaria^

ii. 155.
Clotzsch, hybrids of various trees, ii.

111.
Clover, pelorism in, ii. 338.
COATE, Mr., on interbreeding pigs, ii. 102,
Coccus of apple-trees, ii. 217.
Cochin fowls, i. 237, 263, 264, 273,

274 ; occipital foramen of, figured, i.

274 ; section of skull of, figured, i.

277 ; cervical vertebi'a of, figured, i.

281.
Cochineal, persistence of, ii. 222 ; pre-
ference of, for a particular cactus, ii.

265.
Cochleuria armoracia, ii. 154.
Cock, game, natural selection in, ii.

210; spur of, grafted on the comb,

ii. 286 ; spur of, inserted into the ear

of an ox, ii. 365 ; effect of castration

upon the, ii. 26.
Cock's-COMB, varieties of the, i. 389.
Cocoons of silkworms, variitions in, i.

319.
Codfish, bulldog, i. 93 ; number of

eggs in the, ii. 373.
Ccelogenys paca, ii. 135.
Colin, prepotency of the ass over the

horse, ii. 43 ; on cross-breeding, ii.

75; on change of diet, ii. 293.
Collinson, Peter, peach-tree produc-
ing a nectarine, i. 361.
Coloration in pigeons, an evidence of

unity of descent, i. 204-206.
Colour, correlation of, in dogs, i. 28,

29 ; persistence of, in horses, i. 53 ;

inheritance and diversity of, in

horses, i. 57 ; variations of, in the

i42

COLOUR.

INDEX.

CORALS.

ass, i. 66 ; of tvild or feral cattle, i.
88 ; transmission of, in rabbits, i.
Ill; peculiarities of, in Himalayan
rabbits, i. 114; influence of, ii. 212-
216; correlation of, in head and
limbs, ii. 316 ; correlated with con-
stitutional peculiarities, ii. 329-332.

Colour and odour, correlation of, ii.
317.

Colour-blindness, hereditary, i. 454;
more common in men than in women,
ii. 48, 49 ; associated with inability
to distinguish musical sounds, ii.
322.

Colours, sometimes not blended by
crossing, ii. 70.

Columha affinis, Blyth, a variety of C.
livia, 1. 192.

Columha amalice, Brehm, a variety of
C. livia, i. 192.

Columha guinea, i. 192.

Columha gymnocyclus, Gray, a form of
C. livia, i. 193.

Columha gi/mnophthalmos, hybrids of,
with C. (enas, i. 202 ; with G. mxicU'
losa, i. 203.

Columha mierm<?c?/a, Strickland, a variety
of C. livia, i, 193.

Columha leucocephala, ii. 1 39.

Columha leuconota, i. 191, 205.

Columha littoralis, i. 191.

Columha livia, ii. 2, 14 ; the parent of
domestic breeds of pigeons, i. 192 ;
measurements of, i. 140 ; figured, i.
141; skull figured, i. 172; lower
jaw figured, i. 173 ; scapula figured,
i. 176.

Columha luctuosa, i. 191.

Columha migratoria and leucocephala, di-
minished fertility of, in captivity, ii.
139.

Columha cenas, i. 192 ; crossed with
common pigeon and C. gymnophthal-
mos, i. 203.

Columha palumhus, i. 202, ii. 342.

Columha rupe<tris, i. 191, 193, 205.

Columha schimperi, i. 193.

Columha torquatrix, ii. 342.

Columha turricola, i. 193.

Columbia, cattle of, i. 92.

xJolumbine, double, i. 388, ii. 323.

Columbus, on West Indian dogs, i. 23.

Columella, on Italian shepherd dogs,
i. 23; on domestic fowls, i, 243, 259,

ii. 187, 424 ; on the keeping of ducks,
i. 291 ; on the selection of seed-corn,
i. 336 ; on the benefits of change of
soil to plants, ii. 128; on the value
of native breeds, ii. 304.

Colza, i. 344.

Comb, in fowls, variations of, i. 266 ;
sometimes rudimentary, ii. 306.

Compensation, law of, i. 288.

Compensation of growth, ii. 335-337.

Complexion, connection of, with con-
stitution, ii. 329.

Composite, double flowers of, i. 3s8,
ii. 151, 307.

Conception, earlier in Alderney and
Zetland cows than in other breeds, i.
91.

Conditions of life, changed, eftect of,
ii. 413-414; on horses, i. 54; upon
variation in pigeons, i. 223 ; upon
wheat, i. 333 ; upon trees, i. 384 ; in
producing bud-variation, i. 441 ; ad-
vantages of, ii. 127-130; 160,161;
sterility caused by, ii, 130-149 ;
conducive to variability, ii. 243-249,
388 ; accumulative action of, ii. 249-
252 ; direct action of, ii. 260-282.

Condor, breeding in captivity, ii. 137.

Confinement, effect of, upon the cock,
ii. 97.

Confucius, on the breeding of rabbits
in China, i. 107.

CONOLLY, Mr., on Angora goats, ii.
318.

Constitutional differences in sheep, i
loO; in varieties of apples, i. 370,
371; in pelargoniums, i. 388; in
dahlias, i. 394.

Constitutional peculiarities in straw-
berries, i. 375; in roses, i. 391.

Consumption, hereditary, i. 451 ; pe-
riod of appearance of, ii. 54 ; corre-
lated with complexion, ii. 329.

Contabescence, ii. 149, 150.

Convolvulus batatas, ii. 153, 299.

Convolvulus tricolor, bud-variation in, i.
440.

Cooper, Mr., improvement of vegetables
by selection, ii. 188.

Cooper, White, hereditary peculiarities
of vision, i. 453 ; association of affec-
tions of the eyes with those of other
systems, ii. 321.

Corals, biTd-variation in, i. 398 ; non*

CORBIE.

INDEX.

CROSSING.

443

dilTusiou of cell-gemmules in, ii.
374.

Corbie. See Boitard.

CoRDEMOZ, Dr., seedless plants, ii. 153.

Cornea, opacity of, inherited, i. 453,

Cornus mascula, yellow-fruited, i. 462.

Correlation, ii. 311; of neighbouring
parts, ii. 312 ; of change in the
whole body, and in some of its parts,
ii. 313 ; of homologous parts, ii. 314-
325; inexplicable, ii. 325-357 ; com-
mingling of, with the eflects of other
agencies, ii. 327-329.

Correlation of skull and limbs in
swine, i. 75 ; of tusks and bristles in
swine, i. 79 ; of multiplicity of horns
and coarseness of wool in sheep, i.
98 ; of beak and feet in pigeons, i.
182, 183 ; between nestling down and
colour of plumage in pigeons, i. 204 ;
of changes in silkworms, i. 321 ; in
plants, ii. 204 ; in maize, i. 341 ; in
pigeons, i. 177-180, 228; in fowls, i.
288-289.

Corresponding periods, inheritance at,
ii. 51-57.

Corrientes, dwarf cattle of, i. 92.

CORRINGHAM, Mr., influence of selection
on pigs, ii. 182.

Corsica, ponies of, i. 54.

" CoRTBECK " (pigeon) of Aldrovandi, i.
219.

Corrus corone, and C. comix, hybrids
of, ii. 72.

Corijdalis, flower of, ii. 336.

Corydalis cav, ii. 113, 114.

Corijdilis solida, sterile when peloric, ii.
loU.

Corydalis tvberos't, peloric by reversion,
ii. 33.

Corylus avellana, i. 379.

GosTA, A., on shells transferred from
England to the Mediterranean, ii.
270.

CouES, Dr. E., on a monstrous chicken,
ii. 385.

CowPER, Mr. White, defective develop-
ment of the dental system, ii. 321.

" CouvE Tronchuda," i. 342.

Cow, inheritance of loss of one horn in
the, i. 456 ; amount of milk fur-
nished by the, ii. 290; development
of six mammae in, ii. 309.

Cowslip, ii. 464.

Cracid.t:, sterility of the, in captivity,
ii. 139.

Cranes, fertility of, in captivity, ii
140.

Cratcegus ox>/acantha, i. 387, 402, ii.
217, 246, 461.

Cratcegus monogyna, i. 387.

Cratcegus sibirica, i. 387.

Crawfurd, J., Malasian cats, i. 49;
horses of the Malay Archipelago, i.
51 ; horses of Japan, i. 56 ; occurrence
of stripes in young wild pigs of
Malacca, i. 80 ; on a Burmese hairy
family with deficient teeth, ii. 53,
320 ; Japanese origin of the bantam,
i. 241 ; game fowls of the Philippine
Islands, ii. 243 ; hybrids of Gallus
varius and domestic fowl, i. 246 ;
domestication of Gallus hankiva, i.
248 ; feral fowls in the Pellew Islands,
i. 249 ; history of the fowl, i. 258 ;
history of the domestic duck, i. 291 ;
domestication of the goose, i. 303 ;
cultivated plants of New Zealand, i.
329 ; breeding of tame elephants in
Ava, ii. 132 ; sterility of Goura
coronata in confinement, ii. 139 ;
geese of the Philippine Islands, ii.
145.

Creepers, a breed of fowls, i. 241.

Crested fowl, i. 239 ; figured, i. 240.

" Creve-cceur," a French sub-breed of
fowls, i. 241.

Crisp, Dr., on the brains of the hare
and rabbit, i. 132.

Crocker, C. W., singular form of Be-
gonia frigida, i. 389, ii. 150 ; sterility
in RawincAdus ficaria, ii. 154.

Crocus, ii. 147.

Cross-breeding, permanent effect of,
on the female, i. 436.

Crossing, ii. 62-125, 157-175; a cause
of uniformity, ii. 62-67, 157 ; occurs
in all organised beings, ii. 67-69 ;
some characters not blended by, ii.
67-72, 158; modifications and new
races produced by, ii. 73-77 ; causes
which check, ii. 78-87 ; domestica-
tion and cultivation favourable to,
ii. 88-91, 172; beneficial effects of
ii. 92-112, 158-160; necessary in
some plants, ii, 112-122, 159, 'l60,
418; summary of subject of, ii 122-
126; of dogs with wolves in North

444

CRUSTACEA.

INDEX.

DANIELL.

America, i. 21, 22; with Canis can-
crivo7-us in Guiana, i. 23 ; of dog with
wolf, described by Pliny and othei's,
i. 24 ; characters furnished by,
brought out by reversion in the
progeny, ii. 7-9 ; a direct cause of
reversion, ii. 13-21, 23; a cause of
variability, ii. 252-255.

Crustacea, macrourous, differences in
the development of the, ii. 363.

Crustacean with an antenna-like de-
velopment of the eye-peduncle, ii.
385.

Cryptogamic plants, bud-variation in,
i. 408.

Cuba, wild dogs of, i. 28.

" Cuckoo," sub-breeds of fowls, i. 256.

Cucumber, variation in number of
carpels of, i. 382 ; supjwsed crossing
of varieties of the, i. 4:^0.

Cucumis momordica, i. 384.

Cucumis sativa, i. 382.

Ciicurbita, dwarf, correlation of leaves
in, ii. 324.

Cucurhita maxima, i. 380, 382.

Cucurbita inoschata, i. 380, 382.

Cucurhita pepo, i. 380, ii. 86 ; varieties
of, i. 381 ; relation in size and num-
ber of fruit of, ii. 336.

CUCURBITACE^, 1. 380-384 ; supposed
crossing of, i. 430 ; Naudin's obser-
vations on hybrids of, ii. 156 ; accli-
matisation of, ii. 304.

"CULBUTANTS" (pigeons), i. 156.

CULTIV'ATION of plants, origin of, among
savages, i. 326, 327 ; fertility increased
by, ii. 89-91.

CUNIER, on hei-editary night-blindness,
i. 454.

CuPPLES, Mr., pairing of deer-hounds,
ii. 104.

Currants, of Tierra del Fuego, i. 326 ;
bud-variation in, i. 400.

Curtis, Mr., bud-variation in the rose,
1. 406.

Cuvier, on the gestation of the wolf, i.
30 ; the odour of the jackal, an ob-
stacle to domestication, i. 31 ; diffei'-
ences of the skull in dogs, i. 35 ;
external characters of dogs, i. 36 ;
elongation of the intestines in do-
mestic pigs, i. 77, ii. 293 ; fertility
of the hook-billed duck, i. 291 ; hy-
brid of ass and zebra, ii. 16 ; breed-

ing of animals in the Jardin des
Plantes, ii. 132; sterility of pre-
daceous birds in captivity, ii. 137 ;
facility of hybridisation in confine-
ment, ii. 143.

Cyanosis, affection of fingers in, ii.
326.

Cyclamen, bud-variation in, i. 407.

Cynara cardunculus, ii. 7.

Cynips fecundatrix, ii. 273.

Cynocephalus hamadryas, ii. 136.

Cyprinus auratus, i. 312-313.

Cyrtanthus, ii. 121.

Cyrtopodium, ii. 115.

Cytisus adami, its bud-variation, i.
413-417, ii. 11; seedlings from, i.
414; different views of its origin,
i. 415-417 ; experiments in crossing
C. purpweus and laburnum to pro-
duce, i. 415 ; its production by M.
Adam, i. 416 ; discussion of origin of,
ibid.

Cytisus alpino-lahurnum, ovules and
pollen of, i. 415; origin of, ibid,

Cytisus alpinus, i. 415.

Cytisus laburnum, i. 413, 415, 416.

Cytisus purpureo-elongatus, ovules and
pollen of, i. 415 ; production of, i.
416.

Cytisus purpureus, i. 414-417.

Daiilbohm, effects of food on hymenop-
tera, ii. 270.

Dahlia, i. 393-394, ii. 129; bud-
variation by tubers in the, i. 411;
improvement of, by selection, ii.
201 ; steps in cultivation of, ii. 249 ;
effect of conditions of life on, ii. 263 ;
correlation of form and colour in, ii.
325.

Daisy, hen-and-chicken, i. 389 ; Swan
River, ii. 249.

Dalbret, varieties of wheat, i. 332.

Dalibert, changes in the odours of
plants, ii. 264.

Dally, Dr., on consanguineous mar-
riages, ii. 102.

Daltonism, hereditary, i. 454.

Damaras, cattle ol, i. 91, ii. 192,
193.

Damson, i. 368.

Dandolo, Count, on silkworms, i. 318.

Daniell, fertility of English dogs in
Sierra Leone, ji. 144,

DANISH.

INDEX.

DELPHINIUM.

445

Danish Middens, remains of dogs in, i.
18.

Dappling in horses, asses, and hybrids,
i. 58.

Dareste, C, on the skull of the Polish
fowl, i. 275 ; causes of variability,
ii. 257 ; on the production of mon-
strous chickens, ii. 279; co-existence
of anomalies, ii. 325 ; production of
double monsters, ii. 334.

Darvill, Mr., heredity of good qualities
in horses, i. 456.

Darwin, C, on Lepus magellanicus. i.
117; on the wild potato, i. 349;
dimorphism in the polyanthus and
primrose, i. 464.

Darwin, Dr., improvement of vegeta-
bles by selection, ii. 189.

Darwin, Sir F., wildness of crossed
pigs, ii. 19.

Darwin, G., consanguineous marriages,
ii. 104.

D'Asso, monogynous condition of the
hawthoi-n in Spain, i. 387.

Dasiiprocta aijuti, ii. 135,

Date-palm, varieties of the, ii. 24'^.

Datura, ii. 11; variability in, ii. 254.

Datura Icevis and stramonium, reversion
in hybrids of, i. 425.

Datura stramonium, ii. 43.

Daubenton, variations in the number
of mammae in dogs, i. 36 ; proportions
of intestines in wild and domestic
cats, i. 50, ii. 292.

Daudin, on white rabbits, ii. 215.

Davy, Dr., on sheep in the West Indies,
i. 102.

Dawkins, W. Boro, history of the dog,
i. 15; origin of cattle, i. 85; early
domestication of Bos lonjifrons in
Britain, ibid.

Deaf-mutes, non-heredity in, i. 465.

Deafness, inheritance of, ii. 55.

Dean, potato-grafting, i. 421.

Deby", wild hybrids of common and
musk ducks, ii. 20.

De Candolle, Alph., number and
origin of cultivated plants, i. 323, 324,
395 ; regions which have furnished
no useful plants, i. 327 ; wild wheat,
i. 329, 330 ; wild rye and oats, i. 329 ;
antiquity of varieties of wheat, i. 333 ;
apparent inefficacy of selection in
wheat, i. 335; origin and cultivation

41

of maize, i. 338, ii. 321 ; colours of
seeds of maize, i. 839 ; varieties and
origin of the cabbage, i. 342, 343 ;
origin of the garden-pea, i. 345 ; on
the vine, i. 352, ii. 298 ; cultivated
species of the orange group, i, 355 ;
probable Chinese origin of the peach,
i. 357 ; on the peach and nectarine,
i. 361, 363 ; varieties of the peach, i.
363 ; origin of the apricot, i. 365 ;
origin and varieties of the plum, i.
367 ; origin of the cherry, i. 368 ;
varieties of the gooseberry, i. 376 ;
selection practised with forest-trees,
i. 384 ; wild fustigate oak, i. 385 ;
dark-leaved varieties of trees, i'>id. ;
conversion of stamens into pistils in
the poppy, i. 389 ; variegated foliage,
i. 390 ; heredity of white hyacinths,
i. 395, 463 ; changes in oaks depen-
dent on age, i. 413; inheritance of
anomalous characters, i. 462 ; varia-
tion of plants in theirnative countries,
ii. 244; deciduous bushes becoming
evergreen in hot climates, ii. 295 ;
antiquity of races of plants, ii. 425.

De Candolle, P., non-variability of
monotypic genera, ii. 253 ; relative
development of root and seed in
Raphanus sativus, ii. 335.

Decaisne, on the cultivation of the
wild carrot, i. 344; varieties of the
pear, i. 372 ; intercrossing of straw-
berries, i. 373 ; fruit of the apple, i.
432 ; sterility of Lysimachui nummu-
laria, ii. 154; tender variety of the
peach, ii. 299.

Deer, assumption of horns by feinale,
ii, 26 ; imperfect development of
horns in a, on a voyage, ii. 141.

Deer, fallow, ii. 81.

Deerhound, Scotch, difference in size
of the sexes of, ii. 49 ; deterioration
of, ii. 100.

Degeneration of high-bred races,
under neglect, ii. 225.

De Jonghe, J., on strawberries, i. 374,
ii. 229; soft-barked pears, ii. 217;
on accumulative variation, ii. 249 ;
resistance of blossoms to frost, ii. 297.

Delamer, E, S., on rabbits, i. Ill,
116.

Delphinium ajacis, i. 464.

Delphinium consolid<i, i. 463, 464.

446

DELPINO.

INDEX.

DIXON.

Delpino on Pangenesis, ii. 350, 372.

Dendrocygna viduata, ii. 140.

Denny, H., lice of Aperea, ii. 135.

Dentition, variations of, in the horse,
i. 52.

Deodar, i. 387.

Dksmarest, distribution of white on
dogs, i. 30 ; cat from the Cape of
Good Hope, i. 49 ; cats of Madagascar,
ibid.; occiirrence of striped young in
Turkish pigs, i. 80 ; French breeds
of cattle, i. 84 ; horns of goats, i. 106 ;
on hornless goats, ii. 306.

Desportes, number of varieties of
roses, i, 391.

Devay, Dr., singular case of albinism,
i. 460 ; on the marriage of cousins,
ii. 102 ; on the effiects of close inter-
breeding, ii. 251.

Development and metamorphosis, ii.
383, 384.

Development, arrests of, ii. 306-310.

Development, embryonic, ii. 361-
364.

D'Hervey-Saint-Denys, L.,on the Ya-
mi, or imperial race of the Chinese,
ii. 189.

Dhole, fertility of the, in captivity, ii.
134.

Diabetes, occurrence of, in three bro-
thers, i. 460.

Diant/tus, contabescent plants of, ii.
149, 150 ; hybrid varieties of, ii. 255.

Dianthus armeria and deltoides, hybrids
of, ii. 76.

Dianthus barbatus, i. 406.

iHanthus caryophyllus, i. 406.

Dianthus japonicus, contabescence of
female organs in, ii. 150.

Diapheromera femorata, ii. 359.

Dichogamous plants, li. 68.

Dickson, Mr., on " running " in carna-
nations, i. 407 ; on the colours of
tulips, i. 412.

Dicotyles torquatus and labiatus, ii. 133.

Dieffenbach, dog of New Zealand,
26 ; feral cats in New Zealand,
49; polydactylism in Polynesia,
458.

Dielytra, ii. 33.

Diet, change of, ii. 293, 294.

Digitalis, properties of, aflected by cul-
ture, ii. 264.

Digits, supernumerary, i. 457 ; analogy

of, with embryonic conditions, ii. 16 ;
fusion of, ii. 334.

Dimorphic plants, ii. 112; conditions
of reproduction in, ii. 165-169.

Dimorphism, reciprocal, ii. 68.

Dingo, i. 26 ; variation of, in colour, i.
28 ; half-bred, attempting to burrow,
ibid.; attraction of foxes by a female,
i. 32 ; variations of, in confiuemeut,
ii. 251.

Diceciousness of strawberries, i. 375.

Diseases, inheritance of, i. 451, 452 ;
inherited at corresponding periods of
life, ii. 5.3-57 ; peculiar to localities
and climates, ii. 265 ; obscure corre-
lations in, ii. 325, 326 ; affecting cer-
tain parts of the body, ii. 374; oc-
curring in alternate generations, ii.
396.

Distemper, fatal to white terriers, ii.
213.

Disuse and use of parts, effects of, ii.
285-293, 345, 346, 414, 415; in
the skeleton of rabbits, i. 129-134;
in pigeons, i. 180-187 ; in fowls, i.
284-288; in ducks, i. 299-301; in
the silk-moth, i. 317-;i21.

Divergence, influence of, in producing
breeds of pigeons, i. 230.

Dixon, E. S., on the musk duck, i.
191; on feral ducks, i. 200; on
feral pigeons in Norfolk Island,
ibid. ; crossing of pigeons, i. 201 ;
origin of domestic fowls, i. 242 ;
crossing of Gallus sonneratii and
common fowl, i. 245 ; occurrence of
white in the young chicks of black
fowls, i. 2.t6; Paduan fowl of Aldro-
vandi, i. 259 ; peculiarities of the
eggs of fowls, i. 260 ; chickens, i.
261, 262; late development of the
tail in Cochin cocks, i. 263; comb of
lark-crested fowls, i. 268 ; develop-
ment of webs in Polish fowls, i. 27J ;
on the voice of fowls, il>id. : origin
of the duck, i. 291 ; ducks kept by
the Romans, i, 292 ; domestication of
the goose, i. 302 ; gander frequently
white, i. 303 ; breeds of turkeys, i,
309 ; incubatory instinct of mongrels
of non-sitting races of fowls, ii. 18;
aversion of the dove-cot pigeon to
pair with fancy birds, ii. 82 ; fertility
of the goose, ii. 90 ; general sterility

DOBELL.

INDEX.

DROMEDARY.

447

of the guans in captivity, ii. 139 ;
fertility of geese iu captivity, ii.
140 ; white pea-fowl, ii. 326.

DOBF.LL, H., inheritance of anomalies of
the extremities, i. 458 ; non-reversion
to a malformation, ii. 10.

DouRizHOFFER, abhorrence of incest by
the Abipones, ii. 103.

Dogs, origin of, i. 15 ; ancient breeds of,
i. 17, ii. 424; of Neolithic, Bronze
and Iron periods in Europe, i. 18, 19,
ii. 423 ; resemblance of, to various
species of Canidae, i. 21 ; of Korth
America compared with wolves, i.
21, 22 ; of the West Indies, South
America, and Mexico, i. 23, 32 ; of
Guiana, i. 23 ; naked dogs of Para-
guay and Peru, 24, 31; dumb, on
Juan Fernandez, i. 27 ; of Juan de
Nova, i. 28 ; of La Plata, ibid. ; of
Cuba, ibid. ; of St. Domingo, ibid. ;
correlation of colour in, i. 28, 29 ;
gestation of, i. 30, 31 ; hairless
Turkish, i. 31, ii. 212 ; inter-crossing
of ditierent breeds of, i. 31 ; charac-
ters of dift'erent breeds of, discussed,
i. 34—38 ; degeneration of European,
in warm climates, i. 37, 39 ; ii. 267,
295; liability to certain diseases in
different breeds of, i. 37 and note;
causes of differences cf breeds dis-
cussed, i. 39-45 ; catching fish and
crabs in New Guinea and Tierra del
Fuego, i. 41 ; webbing of t^»e feet in,
ibid. ; influence of selection in pro-
ducing different breeds of, i. 42, 45 ;
retention of originJ habits by, i.
191; inheritance of polydactylism
in, i. 549 ; feral, ii. 6 ; revei'sion in
fourth generation of, ii. 8; of the
Pacific Islands, ii. 64, 205, 393;
mongrel, ii. 70 ; comparative facility
of crossing different breeds of, ii.
80; fertility of, ii. 88, 134; inter-
breeding of, ii. 98-100 ; selection of,
aTiiong the Greeks, ii. 186, 194;
among savages, ii. 191, 192; un-
conscious selection of, ii. 196, 197 ;
valued by the Fuegians, ii. 199, 200;
cllmatal changes in hair of, ii. 268 ;
production of drooping ears in, ii.
291; rejection of bones of game by,
ii. 293 ; inheritance of rudiments of
limbs in, ii. 306 ; development of

fifth toe in, ii. 309 ; hairless, de-
ficiency of teeth in, ii. 319; short-
faced, teeth of, ii. 337 ; probable
analogous variation in, ii. 341 ; ex-
tinction of breeds of, ii. 421.
DoMBRAiN, H. H., on the auricula, ii.

oo

9.

Domestication, essential points in, ii.
400, 401 ; favourable to crossing, ii.
88, 89 ; fertility increased by, ii. 89-
91, 158.

Domesticated animals, origin of, ii.
144, 145; occasional sterility of,
under changed conditions, ii. 145,
146.

DoNDERS, Dr., hereditary hyperme-
tropia, i. 453.

Dorking fowl, i. 237, 274 ; furculum of,
figured, i. 282.

Dormouse, ii. 135.

Double flowers, ii. 151, 152, 155, 156 ;
produced by selection, ii. 184.

Doubleday, H., cultivation of the fil-
bert pine strawberry, i. 376.

Douglas, J., crossing of white and
black game-fowls, ii. 70.

Downing, Mr., wild varieties of tba
hickory, i. 327 ; peaches and n' c-
tarines from seed. i. 36(i, 361 ; ori/'a
of the Boston nectarine, i. 3f 1 ;
American varieties of the peach, i.
364 ; North American apricot, i.
366 ; varieties of the plum, i. 363 ;
origin and vaiieties of the cherry, i.
368, 369 ; " twin-cluster pippiuj," i.
370; varieties of the apple, i. 372;
on strawberries, i. 373, 375 ; fruit
of the wild gooseberry, i. 378 ;
effects of grafting upon the seed, i.
472 ; diseases of plum and peach
tree, ii. 213; injury done to rtone
fruit in America by the " weevil," ii.
217; grafts of the plum and peach,
ii. 247 ; wild varieties of pears, ii.
248 ; varieties of fruit-trees suitable
to different climates, ii. 296.

Downing, Mr. J., sterility of ".'lort-
horns, ii. 97.

Drab I sylvestris, ii. 147.

Dragon (pigeon), i. 146, 1 19.

"Draijer" (pigeon), i. 164.

Drinking, effects of, in diiferen . cli-
mates, il. 279,

PromedaRV, selection of, ii. 190

348

DKrCE.

INDEX.

EHKENBERG.

Druce, Mr., inter-breeding, ii. 99 ; value
of cross breed of pigs, ii. 100.

Du Chaillu, fruit-trees in West Africa,
i. o27.

Duchesne, on Fragaria vesca, i. 373,
375.

DuFOUR, Leon, on Cccidomyia and Miso-
C'cmjjus, i. 5.

Duck, musk, retention of perching
habit by the, i. 191 ; feral hybrid of,
i. 199.

Duck, penguin, hybrid of, with Egyp-
tian goose, ii. 44.

Duck, wild, difficulty of rearing, ii.
219; effects of don^iestication on, ii.
2H7.

Ducks, breeds of, i. 290, 291 ; origin of,
i. 291 ; history of, ibid. ; wild, easily
tamed, i. 292, 293 ; fertility of breeds
of, when crossed, i. 294 ; with the
plumage of Anas bosch'^s, ibid. ;
Malayan penguin, identical in plum-
age with English, ibid. ; characters
of the breeds of, i. 295-299 ; eggs of,
i. 295 ; effects of use and disuse in,
i. 299-302, ii. 288; feral, in Nor-
folk, i. 199 ; Aylesbury, inheritance
of early hatching by, i. 471 ; rever-
sion in, produced by crossing, ii. 14 ;
wildness of half-bred wild, ii. 19 ;
hybrids of, wirh the musk duck, ii.
19, 20; assumption of male plumage
by, ii. 26 ; crossing of Labrador and
penguin, ii. 75 ; increased fertility
of, by domestication, ii. 90 ; general
fertility of, in confinement, ii. 140 ;
increase of size of, by care in breed-
ing, ii. 183 ; change produced by
domestication in, ii. 250.

DUMERIL, Aug., breeding of Siredon in
the branchiferous stage, ii. 379.

Dun-coloured horses, origin of, i. 61.

DUREAU DE LA Malle, feral pigs in
Louisiana, ii. 7 ; feral fowls in
Africa, ibid. ; bud-variation in the
pear, i. 401 ; -production of mules
among the Romans, ii. 88.

Dusicyon sylvestris. i. 23.

Dutch rabbit, i. 111.

Dutch roller pigeon, i. 158.

DuTROCHET, pelorism in the laburnum,
ii. 338.

Duval, growth of pears in woods in
France, ii. 248.

Duval-Jouve, on Leersia oryzoides, ii,

69.
DuVERNOY, self-impotence in Lilium

candidum, ii. 118.
DziERZON, variability in the characters

and habits of bees, i. 314.

Earle, Dr., on coloui'-blindness, ii. 48,
322.

Ears, of fancy rabbits, i. 110; de-
ficiency of, in breeds of rabbits, i.
112 ; rudimentary, in Chinese sheep,
ii. 30G ; drooping, ii. 291 ; fusion of,
ii. 334.

Eaton, J. M., on fancy pigeons, i. 155,
159 ; variability of characters in
breeds of pigeons, i. 169 ; reversion
of crossed pigeons to coloration of
Clumbt livia, i. 208 ; on pigeon-
fancying, i. 216, 225, 226; on
tumbler-pigeons, i. 220, ii. 229 ;
carrier-)iigeon, i. 219 ; effects of
inter-breeding on pigeons, ii. 106;
properties of pigeons, ii. 182 ; death
of short-faced tumblers in the egg,
ii. 211 ; Archangel-])igeon, ii. 226.

ECHINODERMATA, metagenesis in, ii.362.

Ectopisti's, specific difference in number
of tail-feathers in, i. 167.

Ectopistes migratorius, sterile hybrids
of, with Turtur vu'garis, i. 203.

Edentata, correlation of dermal system
and teeth in the, ii. 321.

Edgeworth, Mr., use of grass-seeds as
food in the Punjab, i. 326.

Ed.monston, Dr., on the stomach in
Larus argentatus and the raven, ii.
292.

Edwards and Colin, on English wheat
in France, ii. 297.

Edwards, W. F., absorption of the mi-
nority in crossed races, ii. 64.

Edwards, W. W., occurrence of stripes
in a nearly thoroughbred horse, i.
60 ; in foals of race-horses, I. 62.

Eggs, of fowls, characters of, i. 260 ;
variations of, in ducks, i. 295 ; of the
silk-moth, i. 317.

Egypt, ancient dogs of, i. 17, 18 ; ancient
domestication of the pigeon in, i. 2 14 ;
absence of the fowl in ancient, i. 258.

Egyptian goose, hybrids of, with pen-
guin duck, i. 296

Ehrenberg, Prof., multiple origin of

ELEMENTS.

INDEX.

FALCONER.

449

the dog, i, 16 ; dogs of Lower Egypt,
i. 25 ; mummies of Felis maniculata,
i. 45.

Elemknts of the body, functional inde-
pendence of the, ii. .'^64-366.

Elephant, its sterility in captivity, ii.
132.

Elk, Irish, correlations in the, ii. 327,
328.

Elliot, Sir Walter, on cats in India, i.
46; on striped horses, i. 61 ; Indian
domestic and wild swine, i. 70 ;
pigeons from Cairo and Constanti-
nople, i. 138; fantail pigeons, i. 153;
Lotan tumbler pigeons, i. 158 ; a
pigeon uttering the sound Yahu, i.
163 ; Gallus bankiva in Pegu, i. 248.

Ellis, Mr., varieties of cultivated plants
in Tahiti, ii. 243.

Elm, nearly evergreen Cornish variety
of the, i. 386, ii. 301 ; folia^;e-varieties
ofthe, i. 385.

Elm, weeping, i. 385 ; not reproduced
by seed, i. 462.

Emhcriza passerina, ii. 141.

Embryos, similarity of,' i. 12 ; fusion of,
ii. 333.

Engel, on Laurus sassafras, ii. 264.

England, domestication of Bos longi-
frons in, i. 85 ; selection of horses in,
in mediaeval times, ii. 187 ; laws
against the early slaughter of rams
in, ii. 188.

Ephemerid.i:, development of the, ii.
361.

Epidendrum cinnabarinum, i. 431 ; and
E. zebra, ii. 115.

Epilepsy, hereditary, i. 451, ii. 55.

Equus burchellii, i. 67.

Equus c/ua /ga, i 67.

Equ(S indicus, ii. 17, 22.

Equus teniopus, i. 65, 66, ii. 16.

Erdt, disease of the white parts of cattle,
ii. 331.

Ericace^, frequency of contabescence
in the, ii. 149.

Erichthonius, an improver of horses
by selection, ii. 186.

Erman, on the fat-tailed Kirghisian
sheep, i. 102, ii. 269 ; on the dogs of
the Ostyaks, ii. 191.

Erodlum, ii. 33.

Er_ythri7ia crista-gnlli and E. herbacea,
hybrids of, ii. 253.

Eschscholtzia californica, self-sterile in

England, ii. 118.
Esquilant, INIr., on the naked young of

dun-coloured pigeons, i. 180.
Esquimaux dogs, their resemblance to

wolves, i. 22 ; selection of, ii. 191.
EsQUiROL, onherelitary insanity, i. 55.
Eudes-Deslongchamps, on appendages

under the jaw of pigs, i. 78.
Euoiiymus japonkus i. 4(j7.
Euphorbi c micu at t, ii. 275.
European cultivated plants, still wild

in Europe, i. 324.
Evans, Mr., on the Lotan tumbler

pigeon, i. 158.
Evelyn, pansies grown in his garden,

1. 6

91.

Everest, R., on the Newfoundland dog
in India, i. 37, ii. 295 ; degeneration
of setters in India, i. 39 ; Indian wild
boars, i. 69.

Ewes, hornless, ii. 343.

Extinction of domestic races, i. 232.

Eyes, hereditary peculiarities of the, i.
452—454; loss of, causing microph-
thalmia in children, i. 469 ; modirica-
tion of the structure of, by natural
selection, ii. 207, 2o8.

Eyebrows, hereditary elongation of
hairs in, i. 452.

Eyelids, inherited peculiarities of the,
i. 452.

Eyton, Mr., on gestation in the dog, i.
31 ; variability in number of vertebrae
in the pig, i. 77 ; individual sterility,
ii. 146."

Faba vulgaris, i. 349.

Fabre, observations on ^gilops triti'

coides, i. 330.
Fagus si/lvatica, i. 462.
Fairweather, ]\Ir., production of

double flowers from old seed, ii. 151.
Faivre, on the Frimula sinensis, i. 394,

ii. 324.
Fa/co albidus, resumption of young plu-
mage by, in captivity, ii. 141.
Falco ossifragus, ii. 215.
Fa/co subbuteo, copulating \n captivity,

ii. 137.
Fa/co tlnnunculus, breeding in captivity,

ii. 137.
Falconer, Dr., sterUity of English

bulldogs in India, i. 39 ; resemblanc*

i50

FALCONS.

INDEX.

FITTEST.

between Sivatherium and Niata cattle,
i. 93 ; selection ot the silkworm in
India, i. 317 ; fastigate apple-trees in
Calcutta, 1. 385 ; reproduction of a
supernumerary thumb after amputa-
tion, i. 459 ; fertility of the dhole in
captivity, ii. 134; fertility of English
dogs m India, ii. 144; sterility of the
tiger in captivity, ii. 133 : turkeys at
Delhi, ii. 145 ; on Indian cultivated
plants, ii. 148 ; Thibet mastitf aid
goat, ii. 268.

Falcons, sterility of, in captivity, ii.
137.

Falkland Islands, horses of the, i. 55,
64 ; feral pigs of the, i. 80 ; feral cattle
of the, i. 86, 90 ; feral rabbits of the
i. 116.

Fallow deer, ii. 81, 99.

Fantail pigeons, i. 153-155, ii. 219',
figured, i. 156 ; furculum of. figured,
i. 176; history of, i. 218; absence of
oil-gland in, ii. 336.

Farok Islands, pigeons of the, i. 192.

Fashion, influence of, in breeding, ii.
226.

Fastigate trees, ii. 266, 340.

Faunas, geographical difterences of, i.
10.

" Favourite " bull, ii. 40, 96.

Feathers, homologous variation in, ii.
317.

Feet, of pigeons, individual differences
of, i. 168; cori'elations of external
characters in, i. 180.

Feet and beak, correlation of, in pigeons,
i. 180-184.

Felid^, fertility of, in captivity, ii.
133.

Felts bubastes, i. 45.

Ft lis C'ffra, i. 46.

Felis cal>gul tta, i. 45.

Felis chaus, i. 45-47.

Felis jub'ita, ii. 133.

Felts lybict, i. 46.

Felis m miculata, i. 45.

Felis martul, i. 47.

F&lis ornat ', i. 47.

Fcis syliestris, i. 46.

Falls torqti tta, i. 47.

Female, affected by male element, ii.
361, 382.

Female flov.rers, in male panicle of
maize, i. 339.

Fenn, Mr., grafting potatoes, i. 421.

Fennel, Italian variety of, i. 344.

Feral cats, i. 49 ; cattb, i. 89 ; rabbits,
i. 116, 119; Guinea fowl, i. 310; ani-
mals and plants, reversion in, ii. 5, 6,
22.

Ferguson, Mr., supposed plurality of
oriojin of domestic fowls, i. 243 ;
chickens of black game-fowls, i. 257 ;
relative size of eggs of fowls, i. 260 ;
yolk of eggs of game-fowls, i. 262 ;
early pugnacity of game-cocks, i.
263 ; voice of the Malay fowl, i. 272 ;
effects of interbreeding on fowls, iu
105; selection in Cochin-China fowls,
ii. 180; on fashion in poultry, ii. 226.

Fernandez, on Mexican dogs, i. 23.

Ferns, reproduction of abnormal forms
of, by spores, i. 408 ; non-ditiusion of
cellgemmules in, ii. 373.

Ferrets, ii. 90, 134, 190.

Fertilisation, artificial, of the St.
Valery apple, i. 371, 372.

Fertility", various degrees of, in sheep,
i. 101 ; unlimited mutual, of breeds
of pigeons, i. 201-203; comparative,
of mongrels and hybrids, ii. 78, 79,
162-165 ; influence of nourishment
on, ii. 89 ; diminished by close inter-
breeding, ii. 96, 159; reduced, of
Chillingham wild cattle, ii. 97 ; of
domesticated varieties when crossed,
ii. 173.

Festuca, species of, propagated by bulb-
lets, ii, 154.

P'ilberts, spared by tomtits, ii. 216.

KiLiPPi, on the breeding of brauchiferous
tritons, ii. 379.

Finches, general sterility of, in cap-
tivity, ii. 137.

FiNNiKiN (pigeon), i. 164.

FiNOCCHio, i. 344.

Fir, Scotch, acclimatisation of, ii. 300.

Fish, Mr., advantage of change of soil
to plants, ii. 129.

Fishes, regeneration of portions of fins
of, ii. 15; variability of", when kept in
tanks, ii. 246 ; marine, living in fresh
water, ii. 294 ; double monsters of, ii.
333.

Fission and gemmation, ii. 351.

F'lTCH, Mr., persistency of a variety of
the pea, i. 349.

Fittest, survival of the, i. 6.

FITZINGER.

INDEX.

FKAGARIA.

451

FirznuGER, origin of sheep, i. 98 ; Afri-
can maued sheep, i. 100.

FiTZPATRiCK, Mr., potato-grafting, i.
421.

Fixedness of character, conditions of,
discussed, ii. 37-39.

Flax, found in the Swiss lake-dwellings,
i. 335; climatal difference in products
of, ii. 264.

Fleece, fineness of, in Austrian merinos,
ii. 181.

Fleischmann, on German sheep crossed
with merinos, ii. 66.

" Florentiner-Taube," i. 149, 150.

Flounder, ii. 28.

Flourens, crossing of wolf and dog, i.
33 ; prepotency of the jackal over the
dog, ii. 43 ; hybrids of the horse and
ass, ii. 43 ; breeding of monkeys in
Europe, ii. 135.

Flower-garden, earliest known, in
Europe, ii. 202.

Flowers, capricious transmission of
colour-varieties in, i. 463, 464 ; ten-
dency to uniformity in striped, ii. 45 ;
scorching of, dependent on colour,
ii. 214 ; change in, caused by condi-
tions of life, ii. 262 ; rudimentary, ii.
307 ; relative position of, to the axis,
ii. 337.

Fcetation, abdominal, ii. 285.

Foley, Mr., wild varieties of pears, ii.
248.

Foliage, inherited peculiarities of, i.
385 ; variegation of, i. 390 ; bud-
variation in, i. 407-409.

Food, inHuonce of, on the pig, i. 76 : on
cattle, i. 94 ; excess of, a cause of va-
riability, ii. 244.

Forbes, D., on Chilian sheep, i. 99 ; on
the horses of Spain, Chili, and the
Pampas, i. 54.

Formica 7'uf'i, ii. 238.

Fortune, R., sterility of the sweet
potato in China, ii. 153; development
of axillary bulbs in the yam, ibid.

Fowl, common, breeds of, i. 236-242 ;
supposed plurality of origin, i. 242;
early history of, i. 243-245 ; causes
of production of breeds of, i. 245 ;
origin of, from Gallus batikiva, i. 247-
251, 257 ; feral, notices of, i. 249,
250 ; reversion and analogous varia-
tion in, i. 251-258, ii. 9, 12-14, J

341,343; "cuckoo" sub-breeds of,
i. 256 ; history of, i. 258-260; struc-
tural characters of, i. 260-262 ; sex-
ual peculiarities of, i. 263-270, ii.
50; external diti'erences of, i. 270-273;
differences of breeds of, from G. b m-
kioa, i. 272 ; osteological characters
of, 273-284 ; effects of disuse of parts
in, i. 284-288, ii. 288 ; feral, i. 199,
ii. 7 ; polydactylism in, i. 458 ; fer-
tility of, increased by domestication,
ii. 90, 145 ; sterility of, under certain
conditions, ii. 144; influence of selec-
tion on, ii. 180, 182, 194; evils of
close inter-breeding of, ii. 104, 105;
crossing of, ii. 73-75 ; prepotency
of transmission in, ii. 42 ; rudimen-
tary organs in, ii. 306 ; crossing of
non-sitting varieties of, ii. 18,19;
homology of wing and leg feathei's
in, ii. 315; hybrids of, with phea-
sants and Gallus sonneratii, ii. 20;
black-skinned, ii. 194; black, preyed
upon by the osprey in Irelind, ii. 215;
five-toed, mentioned by Columella, ii.
424; rumpless, tailed chickens pro-
duced by, ii. 4 ; Dorking, crosses of,
ii. 70 ; form of comb and colour of
plumage in, ii. 224; game, crossing
of white and black, ii. 70 ; five-
spurred, ii. 386 ; Spanish, liable to
suffer from frost, ii. 296 ; Polish,
peculiarities of skull of, ii. 326-327.

Fox, sterility of, in captivity, ii. 134.

Fox, S. Bevan, races of bees, i. 314.

Fox, \V. Darwin, gestation of the dog,
i. 31 ; "Negro" cat, i. 48 ; rever-
sion of sheep in colour, ii. 3 ; period
of gestation in the pig, i. 77 ; young
of the Himalayan rabbit, i. 114;
crossing of wild and domestic turkevs,
i. 308 ; reversion in crossed musk
ducks, ii. 14 ; spontaneous segrega-
tion of varieties of geese, ii. 82 ;
effects of close inter-breeding upon
bloodhounds, ii. 100 ; deafness of
white cats with blue eyes, ii. 322.

Foxhounds, i. 42, ii. 99.

Fragaria chiloensis, i. 373.

Fragaria col Una, i. 373.

Fragaria dioica of Duchesne, i. 375.

Fragaria elatior, i. 373.

Fragaria grandiflora, i. 373.

Fragana vesca, i. 373.

i52

FRAGAKIA.

INDEX.

GAHNETT.

Fragaria virginiana, i. 373,

Fraxinus excehior, i. 384, 408, 462,

Fra.rinus lentiscifoUa, i, 462.

Friesland cattle, probably descended
from Bos primigenms, i. 84,

Frillback pigeon, i. 163 ; Indian, i.
161.

Fringilla ciris, ii. 1''7.

Fringilla s/wns, ii, 137.

Frizzled fowls, i. 241 ; horses, i, 56,

Frog, polydactylism in the, i. 458.

Fruit, seedless, ii. 152,

Fruit-trees, varieties of, occurring
wild, i, 327,

Fry, Mr., on fertile hybrid cats, i. 46 ;
on feral fowls in Ascension, i. 249.

{"UCHSIAS, origin of, i. 388 ; bud-varia-
tion in, i. 407.

Fuchsia coccinea and fu^gens, twin seed
produced by crossing, i. 426.

FUEGIANS, their supers^iticn about
killing young water-fowl, i. 327 ;
selection of dogs by the, ii. 191;
their comparative estimation of dogs
and old women, ii. 199 ; their power
of distant vision, ii. 208.

Fungi, parasitic, ii. 274, 275.

FiJRBRiNGER, Dr., ou nails of Saurians,
ii. 386.

FURCULUM, characters and variations of
the, in pigeons, i. 176 ; alteration of,
by disuse, in pigeons, i. 185; cha-
racters of, in fowls, i. 282.

Fusion of homologous parts, ii. 387.

Gait, inheritance of peculiarities of, i.

450.
Galapagos Archipelago, its peculiar

fauna and flora, i. 9.
Galcobdolon luteuin, pelorism in, ii. 33,

337.
Gali^, ii. 272-274.
Gall-gnats, ii, 273,
Gall-like excrescences not inherited,

ii. 23.
Gallinaceous birds, restrict^^d range

of large, i, 249 ; general fertility of,

in captivity, ii. 139,
Gallinula chloropus, ii. 140.
Gallinula nesiotis, i. 302.
Gallesio, species of oranges, i, 355-

357 ; hybridisation of oranges, i, 357 ;

persistency of races in the peach, i,

360 ; supposed specific distinctions of

peach and nectarine, i, 361; bizzarria
orange, i. 417 ; crossing of red and
white carnations, i, 426 ; crossing of
the orange and lemon, i. 430, ii. 360 ;
eft'ect of foreign pollen on maize, i,
130 ; spontaneous crossing of oranges,
ii. 68; monstrosities a cause of steri-
lity in plants, ii, 150; seeding of
ordinarily seedless friiits, ii, 152 ; ste-
rility of the sugar-cane, ii, 153; ten-
dency of male flowers to become
double, ii, 155; effects of selection iu
enlarging fruit, &c,, ii, 202 ; varia-
tion of the orange-tree in North
Italy, ii. 243 ; naturalisation of the
orange in Italy, ii, 298,

Galtus ceneus, a hvbrid of G. varius and
the domestic fowl, i. 246.

Gallus hankiva, probable original of do-
mestic fowls, i. 245, 247-251,257;
game-fowl, nearest to, i. 237 : crossed
with G. sonneratii, i. 246 ; its cha-
racter and habits, i. 246, ii. 88 ; dif-
ferences of various breeds of fowls
from, i. 272 ; occipital foramen of,
figured, i. 274; skull of, figured, i.
275 ; cervical vertebra of, figured, i.
281 ; furculura of, figured, i, 282 ; re-
version to, in crossed fowls, ii. 13, 14 ;
hybrid of, with G. varius, i. 246, ii.
14; number of eggs of, ii. 90.

Gallus ferrugineus, i. 237.

Gallus furcatu^s, i. 246.

Gallus giganteus, i. 246.

Gallus sonneratii, characters and habits
of, i. 245 ; hybrids of, i. 245, ii. 20

Gallus stanleyi, hybrids of, i. 246.

Gallus tetnminckii, probably a hybrid,
i. 246.

Gallus varius, characters and habits of,
i. 246 ; hybrids and probable hybrids
of, i. 246,

Galton, Mr., fondness of savages for
taming animals, i, 20, ii, 144 ; cattle
of Benguela, i. 91 ; on hereditary
talent, i. 451 ; on Pangenesis, ii. 350.

Gambier, Lord, his early cultivation of
the pansy, 1. 392.

Game-fowl, i. 237, 263-265.

GAPiS, ii. 213.

Garcilazo de la Vega, annual hunts ^f
the Peruvian Incas, ii. 192.

Garnett, Mr., migratory propensities
of hvbrid ducks, ii. 20.

GAKROD.

INDEX.

GEOFFEOT.

453

Garrod, Dr., on hereditary gout, i. 451.

Gartner, on the sterility of hybrids, i.
201, ii. 79, 169; acquired sterility of
varieties of plants when crossed, i.
381 ; sterility in transplanted plants,
and in the lilac in Germany, ii. 148 ;
mutual sterility of blue and red
flowers of the pimpernel, ii. 173 ;
supposed rules of transmission in
crossing plants, ii. 42 ; on crossing
plants, ii. 76, 107, 111, 112; on re-
peated crossing, ii. 255 ; absorption
of one species by another, when
crossed, ii. 65 ; crossing of varieties
of the pea, i. 428 ; crossing maize, ii.
82 ; crossing of species of Vefbascum,
ii. 71, 83; reversion in hybrids, ii.
9, 23, 24 ; of Cereus, i. 425 ; of 2'ro-
poBolum majus and minus, i. 425 ; va-
riability of hybrids, ii. 253 ; varia-
ble hybrids from one variable parent,
ii. 258 ; graft hybrid produced by
inoculation in the vine, i. 419 ;
effect produced by grafts on the stock
i. 418, ii. 267; tendency of hybrid
plants to produce double flowers, ii.
155 ; production of perfect fruit by
sterile hybrids, ii. 156 ; sexual elec-
tive affinity, ii. 164; self-impotence
in Lobelia, Verba-cum, Lilium, and
Fassijiora, ii. 117, 118; on the action
of pollen, ii. 86 ; tertilisation of
Malva, i. 434, ii. 356 ; prepotency of
pollen, ii. 171 ; prepotency of trans-
mission in species of Nicotiana, ii. 43 ;
bud-variation in Pelargonium zonale,
i. 402 ; in (Enothera biennis, i. 407 ;
in Achillcea millefolium, i. 440 ; effect
of manure on the fertility of plants,
ii. 147 ; on contabescence, ii. 149—
150 ; inheritance of plasticity, ii.
227 ; villosity of plants, ii. 267.

Gasparini, a genus of pumpkins,
founded on stigmatic characters, i.
382.

Gaudichaud, bud-variation in the pear,
i. 401 ; apple-tree with two kinds of
fruit on branch, i. 425.

Gay, on Fragaria grandiflora, i. 373 ;
on Viola lutea and tricolor, i. 392 ; on
the nectary of Viola grandiflora, i.
393.

Gayal, domestication of the, i. 86.

Gayot. See Moll.

Geese (anseres), general fertility of, la
captivity, ii. 140.

Gemmation and fission, ii. 351.

Gemmules, or cell-gemmules, ii. 370,
372-377, 380.

Generation, alternate, ii. 354, 363,
385.

Generation, sexual, ii. 352-357.

Genet, fertility of the, in captivity, ii.
134.

Genius, inheritance of, i. 451.

Gentiana amarella, ii. l.")2.

Geoffroy Saint-Hilaire, production
of monstrous chickens, ii. 279 ; " Loi
de I'ajflnite' de so i pour soi," ii. 333;
compensation of growth, ii. 335.

Geoffroy Saint-Hilaire, Isid., origin
of the dog, i. 16 ; barking of a jackal,
i. 28 ; period of gestation and odour of
the jackal, i. 31 ; anomalies in the
teeth of dogs, i. 36 ; variations in the
proportions of dogs, ibid. ; weObed
feet of Newfoundland doi:s, i. 41 ;
crossing of domestic and wild cats, i.
46 ; domestication of the arni, i. 8 J ;
supposed introduction of cattle into
Europe from the East, ibid. ; absence
of interdigital pits in sheep, i. 99 ;
origin of the goat, i. 105 ; feral geese,
i. 2\)0 ; anci nt historv of the fowl,
i. 258 ; skull of the Polish fowl, i.
275 ; preference of the Romans for
the liver of white geese, i. 305 :
polydactylism, i. 457 ; assumption
of male characters by female bird, ii.
26 ; transmission and blending of
characters in hybrids, ii. 72 ; refusal
of animals to breed in captivity, ii.
131 ; on the Guinea-pig, ii. 135 ;
silkworms producing white cocoons,
ii. 183 ; on the carp, ii. 222 ; on
Helix laden, ii. 270 ; on monstrosities,
ii. 241 ; injury to the embryo a cause
of monstrosity, ii. 257 ; alteration in
the coat of horses in coal-mines, ii.
268 ; kngth of the intestines in wild
and tame animals, ii. 292, 29 < ; in-
heritance of rudimentary limbs in
the dog, ii. 306 ; correlation ia
monstrosities, ii. 312 ; supernu-
merary digits in man, ii. 314; co-
existence of anomalies, ii. 325 ;
presence of hairs and teeth in
ovarian tumours, ii. 365 ; develop-

154

GEOGRAPHICAL.

INDEX.

GODKON.

ment of teeth on the palate in the
horse, ii. 375.

Geographical differences of faunas, i.
10.

Gkological succession of organisms,
i. 11.

Gera>ii"m, ii. 33.

Geraninm phceum and pyrenatcum, ii.
246.

Geran'nm pratense, i. 404.

Gerard, asserted dimatal change in
Burgundian bees, i. 314.

Gerarde, on varieties of the hyacinth,
i. 394.

Gerstacker, on hive-bees, i. 315.

Gervais, Prof, origin of the dog, i.
16 ; resemblance of dogs and jackals,
i. 25 ; taming of the jackal, i. 27 ;
number of teeth in dogs, i. 36 ; breeds
of dogs, i. 38 ; on tertiary horses, i.
53 ; Biblical notices of horses, i. 57 ;
species of Ovis, i. 97 ; wild and
domestic rabbits, i. 107 ; rabbits
from Mount Sinai and Algeria, i.
109; earless rabbits, i. 112; batra-
chia with doubled limbs, ii. 385.

Gestation, period of, in the dog, wolf,
&c., i. 30, 31 ; in the pig, i. 77; in
cattle, i. 90, ii. 313; in sheep, i.
101.

Gestures, inheritance of peculiarities
in, i. 450.

" GnooNDOOKS " a sub-breed of fowls,
i. 241.

Ghor-Khur, ii. 17.

Giles, Mr., effect of cross-breeding in
the pig, i. 436.

Giraffe, co-ordination of structure of,
ii. 206.

GiRARD, period of appearance of perma-
nent teeth in dogs, i. 36.

Giraud-Teulon, cause of short sight,
i. 453.

^IROU de Buzareingues, inheritance in
the horse, i. 455 ; reversion by age in
cattl-', ii. 12; prepotency of trans-
mission of character in sheep and
cattle, ii. 41 ; on crossing gourds, ii.
86.

GiSBURNE, wild cattle at, i. 88.

Gladiolus, i. 388 ; self-impotence of
hybrids of, ii. 121.

Gladiolus colvillii, bud-variation in, i.
407.

Glands, compensatory development of,
ii. 290.

Glastonbury thorn, i. 387.

Glenny, Mr., on the Cineraria, ii. 184.

Gloede, F., on strawberries, i. 375.

Gloger, on the wings of ducks, ii. 288.

" Glouglou " (pigeon), i. 162.

Gloxinia:, peloric, i. 389; ii. 150.

Gmelin, on red cats, at Tobolsk, i. 49,

Goat, i. 105, 106, ii. 6 ; polydact\ lism
in the, i. 549 ; sexual differences in
horns of, ii. 49 ; valued by South
Africans, ii. 193; Thibet, ii. 268;
amount of milk and development of
udders in the, ii. 290 ; hornless, rudi-
mentary bony cores in, ii. 306 ;
Angora, ii. 318.

Godixe, on prepotency of transmission,
ii. 41.

Godron, odour of the hairless Turkish
dog, 1. 31 ; differences in the skull of
dogs, i. 35 ; increase of breeds of
horses, i. 53 ; crossing of domestic
and wild swine, i. 69 ; on goats, i.
10.5, 106 ; colour of the skin in fowls,
i. 2(1; bees of north and south of
France, i. 314; introduction of the
silkworm into Europe, i. 317 ; vari-
ability in the silkworm, i. 321 ; sup-
posed species of wheat, i. 330, 331 ;
on ^gilops triticoides, i. 330 ; vari-
able presence of barbs in grasses, i.
331 ; colours of the seeds of maize, i.
339 ; unity of character in cabbages,
i. 342 ; correlation of colour and
odour, i. 343 ; effect of heat and
moisture on the cabbage, ibid. ; on
the cultivated species of Brassica, i.
344 ; on the Rouncival and sugar
peas, i. 346 ; variation in the num-
bers of peas in the same pod, i. 347 ;
wild vines in Spain, i. 352 ; on
raising peaches from seed, i. 360;
supposed specific distinctness of peach
and nectarine, i. 361 ; nectarine pro-
ducing peaches, i. 362 ; on the flower
of Corydalis, ii. 336 ; origin and
variations of the plum, i. 367 ; origin
of the cherry, i. 368 ; reversion of
single-leaved strawberries, i. 375 ;
five-leaved variety of Fragarin collina,
ibid. ; supposed immutability of
specific characters, i. 381, 382 ;
varieties of Bobinia, i. 385 ; per-

GOETHE.

INDEX.

GREENHOW.

455

inanency of the simple-leaved ash, i.
386 ; non-inheritance of certain
mutilations, i. 466 ; wild turnips,
carrots, and celery, ii. 7 ; peloria, ii.
34 ; prepotency of a goat-like ram,
ii. 41 ; benefit of change of soil to
pUints, ii. 128; fertility of peloric
flowers of Corydalis solida, li. 150 ;
seeding of ordinarily seedless fruit,
ii. 152 ; sexual sterility of plants
propagated by buds, &c., ii. 153 ; in-
crease of sugar in beet-root, ii. 185 ;
effects of selection in enlarging par-
ticular parts of plants, ii. 2o2 ;
growth of the cabbage in the tropics,
ii. 267 ; rejection of bitter almonds
by mice, ii. 218; influence of marshy
pasture on the fleece of sheep, ii. 268 ;
on the ears of ancient Egyptian pigs,
ii. 291 ; primitive distinctness of
species, ii, 410 ; solid-hoofed swine,
ii. 424.

Goethe, on compensation of growth,
ii. 335.

Gold-fish, i. 312, 313, ii. 222.

GOMARA, on South American cats, i.
48.

GoxGORA, number of seeds in the, ii.
373.

Goodman, thiee-toed cows, i. 459.

Goose, ancient domestication of, i. 802 ;
sacred to Juno in Rome, ibid. ; inflexi-
bility of organisation of, i. 303 ; skull
perforated in tufted, ibid. ; charac-
ters of breeds and sub-breeds of, i.
303, 304 ; variety of, from Sebastopol,
i. 304, ii. 386 ; feral, in La Plata, i.
199; Egyptian, hybrid of, with pen-
guin duck, ii. 43 ; spontaneous
segregation of varieties of, ii. 82 ;
fertility of, increased by domestica-
tion, ii. 90 ; decreased fertility of, in
Bogota, ii. 145 ; sterility of, in the
Philippine Islands, i'nd. ; selection
of, ii. 1 88 ; white, preference of the
Romans for the liver of, ii. 194 ;
persistency of character in, ii. 241 ;
Egyptian, change in breeding season
of, 'ii. 294.

Gooseberrv, i. 376-378; bud-variation
in the, i. 400 ; Whitesmith's, ii.
218.

Goppert, on monstrous poppies, ii. 150.

Gosse, p. H., feral dogs in Jamaica, i.

80

28; feral pigs of Jamaica, i. u^ ,
feral rabbits of Jamaica, i. 116 ; on
Columba leucocephala, i. 192; feral
Guinea fowl in Jamaica, i. 199 ; re-
production of individual pe(^uliarities
by gemmation in a coral, i. 398 ;
frequency of striped legs in mules,
ii. 16.
Gould, Dr., on hereditary haemorrhage,

i. 451.
Gould, John, origin of the turkey, i.

308.
Goura coronata and Victorioe^ hybrids

of, i. 203, ii. 138.
Gourds, i. 381 ; crossing of varieties of,
ii. 86 ; ancient Peruvian variety of,
ii. 425.
Gout, inheritance of, i. 451 ; period of

appearance of, ii. 54.
Graba, on the pigeon of the Faroe

Islands, i. 192.
Grafting, ii. 129; effects of, ii. 246,
267 ; upon the stock, i. 413-422 ;
upon the variability of trees, ii. 246 ;
changes analogous to bud-variation
produced bv, i. 413, 415.
Graft-hybrids, i. 413, 417-422, ii. 360.
Grapes, bud-variation in, i. 399 ; ci'oss
of white and purple, i. 419 ; green,
liable to disease, ii. 330 ; effect of
foreign pollen on, i. 430.
Grasses, seeds of, used as food by

savages, i. 324-326.
Gray, Asa, superior wild varieties of
fruit-trees, i. 327 ; cultivated native
plants of North America, i. 329, 380 ;
non-variation of weeds, i. 335 ; sup-
posed spontaneous crossing of Cucur-
bitacese, ,i. 430 ; pre-ordination of
variation, ii. 428; progeny of husked
form of maize, i. 339 ; wild inter-
mediate forms of strawberries, i. 373.
Gray, G. R., on Coluniba gymnocydus, i.

193.
Gray, J. E., on Sus pHciceps, i. 72 : on
a variety of the gold-fish, i. 313 ;
hybrids of the ass and zebra, ii. 16,
17 ; on the breeding of animals at
Knowsley, ii. 131; on the breeding
of birds in captivity, ii. 140.
Greene, J. Reay, on the development

of the echinodermata, ii. 362.
Greenhow, Mr., on a Canadian web»
footed dog, i 41.

t56

GREENING

INDEX.

HARE.

Greening, Mr., experiments on Abraxas
grossulariata, ii. 270.

Gregson, Mr., experiments on Abraxas
grossulariiita, ii. 270.

Grey, Sir George, preservation of seed-
bearing plants by the Australian sa-
vages, i. 327 ; detestation of incest by
Australian savages, ii. 103.

Greyhounds, sculptured on Egyptian
monuments, and in the Villa of Anto-
ninus, i. 17 ; modern breed of, i. 43 ;
crossed with the bulldog, by Lord
Orford, ii. 73 ; close interbreeding of,
;i, 100 ; co-ordination of structure
of, due to selection, ii. 206, 207 ;
Italian, ii. 212.

Greyness, inherited at corresponding
periods of life, ii. 53,

Grieve, Mr., on early-flowering dahlias,
i. 394.

Grigor, Mr., acclimatisation of the
Scotch fir, ii. 300.

Gronland, hybrids of jEgilops and
wheat, ii. 88.

Groom-Napier, C. 0., on the webbed
feet of the otter-hound, i. 41.

Gros, on Pangenesis, ii. 350.

" Grosses-gorges " (pigeons), i. 143.

Ground-tumbler, Indian, i. 157.

Grouse, fertility of, in captivity, ii.
139.

Griis montigresia, cinerca, and antigonc^
ii. 140.

Guana cos, selection of, ii. 192.

GuANS, general fertility of, in captivity,
ii. 139.

Guelder-rose, ii. 169.

Gueldkrland fowls, i. 241.

Guiana, selection of dogs by the Indians
of, ii. 191.

Guinea fowl, i. 310 ; feral, in Ascension
and Jamaica, i. 200, ii. 7 ; indiffer-
ence of, to change of climate, ii. 145.

Guinea pig, i. 467, ii. 135.

Guldenstadt, on the jackal, i. 25.

Gull, herring, breeding in confinement,
ii. 141.

Gulls, general sterility of, in captivity,
ii. 141.

Gulo, sterility of, in captivity, ii. 134.

GiJNTHER, A., on tufted ducks and
geese, i. 289 ; on the regeneration of
lost parts in batrachia, ii. 358.

Gurney, Mr., owls breeding in cap-

tivity, ii. 137 ; appearance of" black-
shouldered " among ordinary pea-
cocks, i. 306.

Habit, influence of, in acclimatisation,
ii. 302-305.

Hackel, on fissiparous reproduction, ii.
357 ; on cells, ii. 366 ; on the double
reproduction of medusae, ii. 379 ; on
inheritance, ii. 391.

Hackles, peculiarities of, in fowls, i.
266.

Hair, on the face, inheritance of, in
man, i. 449 : peculiar lock of, in-
herited, ihid. ; growth of, under
stimulation of skin, ii. 319; homo-
logous variation of, ii. 318 ; develop-
ment of, in the brain, ii. 386.

Hair and teeth, correlation of, ii. 319-
321.

Hairv family, corresponding period of
inheritance in, ii. 53.

Half-castes, character of, ii. 21.

Half-lop rabbits, fi'^ured and described,
i. Ill, 112; skull of, i. 124.

Hijlicptus leucocephalus, copulating in
captivity, ii. 137.

Hallam, Col., on a two-legged race of
pigs, i. 448.

Hallet, Major, selection in cereals, i.
184; on pedigree wheat, i. 332.

Hamburgh fowl, i. 238, 274 ; figured,
i. 239.

Hamilton, wild cattle of, i. 87.

Hamilton, Dr., on the assumption of
male plumage by the hen pheasant,
ii. 26.

Hamilton, F. Buchanan, on the shad-
dock, i. 355 ; varieties of Indian culti-
vated plants, ii. 243.

Hancock, Mr., sterility of tamed birds,
ii. 138, 140.

Handwriting, inheritance of pecu-
liarities in, i. 449.

Hanmer, Sir J., on selection of flower-
seeds, ii. 188.

Hansell, Mr., inheritance of dark yolks
in duck's eggs, i. 295.

Harcourt, E. v., on the Arab boar-
hound, i. 18; aversion of the Arabs
to dun-coloured horses, i. 58.

Hardy, Mr., effect of excess of nourish-
ment or: plants, ii. 244.

Hare, hybrids of, with rabbit, i. 109;

HAKE-LIP.

INDEX.

HEWITT.

457

sterility of the, in confinement, ii.
135 ; }>refcrence of, for particular
plants, ii. 218.

Hare-lip, inheritance of, i. 466.

Harlan, Dr:j on hereditary diseases, i.
451.

Hartman, on the wild ass, i. 05.

Harvev, Mr., monstrous red and white
African bull, i. 95.

Harvey, Prof., singular form of Begonia '
frigida, i. 389 ; ejects of cross-breed-
ing on the female, i. 436 ; monstrous
saxifrage, ii. 150.

Hasora wheat, i. 331.

Hautbois strawberry, i. 375.

Hawker, Col., on call or decoy ducks,
i. 296.

Hawthorn, varieties of, i. 385, 387 ; py-
ramidal, i. 385 ; pendulous hybridised,
i. 461; changes of, by age, i. 387,
413 ; bud-variation in the, i, 402 ;
flower buds of, attacked by bull-
finches, ii. 217.

Hayes, Dr., character of Esquimaux
dogs, i. 22.

Haywood, W., o:i the feral rabbits of
Porto Santo, i. 117.

Hazel, purple-leaved, i, 385, 419, ii.
324.

Head of wild boar and Yorkshire pig,
figured, i. 75.

Head and limbs, correlated variability
of, ii. 315.

Headache, inheritance of, ii. 55.

Heartsease, i. 391-393 ; change pro-
duced in the, by transplantation, i.
413 ; reversion in, ii. 4, 22 ; effects of
selection on, ii. 184; scorching of, ii.
214 ; effects of seasonal conditions on
the, ii. 263 ; annual varieties of the,
ii. 295.

Heat, effect of, upon the fleece of sheep,
i. 102.

Heber, Bishop, on the breeding of the
rhinoceros in captivity, ii. 132.

Hebrides, cattle of the, i. 84 ; pigeons
of the, i. 192.

Heer, 0., on the plants of the Swiss
lake-dwellings, i. 326, ii. 200, 422 ;
on the cereals, i. 335-337 ; on the
peas, i. 345 ; on the vine growing in
Italy in the Bronze age, i. 352.

Heimann, potato-grafting, i. 422.

Helix lactea, ii. 270.

Henicrocallis ful ca and flaca, interchang*
ing by bud-variation, i. 412.

Hemlock, yields no conicine in Scotl/nd,
ii. 264.

Hemp, differences of, in various parts of
India, ii. 148 ; climatal difference in
products of, ii. 264.

Hempseed, effect of, upon the colour of
birds, ii. 269.

Hermaphrodite flowers, occurrence of,
in maize, i. 339.

Hen, assumption of male characters by
the, ii. 26, 29 ; development of spurs
in the, ii. 310.

"HENNlES,"or hen-like male fowls,!.
264.

Henry, T. A., a variety of the ash pro-
duced by grafting, i. 418; crossing
of species o( lihodudendron and Arabis,
i. 431.

Henslow, Prof., individual variation in
wheat, i. 332 ; bud-variation in the
Austrian bramble rose, i. 406 ; partial
reproduction of the weeping ash by
seed, i. 462.

Hepatica, changed by transplantation,
i. 412.

Herbert, Dr., variations of T'7o'a
g)-andifiora, i. 392 ; bud-variation in
camellias, i. 401 ; seedlings from
reverted Cyfisus adam, i. 414 ;
crosses of Swedish and other turnips,
ii. 71 ; on hollyhocks, ii. 185; breed-
ing of hybrids, ii. 112 ; self-impotence
in hybrid hippeastrums, ii. 120, 121 ;
hybrid Gladiolus, ii. 121; or Zephyr-
anthes Candida, ii. 147 ; fertility of
the crocus, ii. 148 ; on contabescence,
ii. 149 ; hybrid Ehododendron, ii.
253.

Herculaneum, figure of a pig found
in, i. 71.

Heron, Sir R., appearance of "black-
shouldered " among ordinary pea-
cocks, i. 306,307 ; non-inheritance of
monstrous characters by gold-fish, i.
313; crossing of white and coloured
Angora rabbits, ii. 70 ; crosses of
solid-hoofed pigs, ibid.

Herpestes fascia us and griseus, ii. 134.

Heusinger, on the sheep of the Taren-
tino, ii. 212; on correlated constita*
tional peculiarities, ii. 331.

Hewitt, Mr., reversion in bantam cocks,

158

HIBBERT.

INDEX.

HOMOLOGOUS.

i. 251 ; degeneration of silk fowls, i.
255; partial sterility of hen-like
male fowls, i. 265 ; production of
tailed chickens by rumpless fowls, i.
271; on taming and rearing wild
ducks, i. 292, ii. 219, 250 ; conditions
of inheritance in laced Sebright ban-
tams, i. 46); reversion in iunipless
fowls, ii. 4 ; reversion in fowls by
age, ii. 13 ; hybrids of pheasant and
fowl, ii. 19, 43; assumption of male
characters by female pheasants, ii.
26 ; development of latent characters
in a barren bantam hen, ii. 29 ;
mongrels from the silk-fowl, ii. 42;
effects of close inter-breeding on fowls,
ii. 105, 106 ; on feather-legged
bantams, ii. 314.

HiBBERT, Mr., on the pigs of the Shet-
land Islands, i. 74.

Hibiscus. See Parit'mn.

Highland cattle, descended from Bos
lon]ifrons, i. 85.

HiLDEBRAND, Dr., on graft-hybrids
with the potato, i. 420 ; on the in-
fluence of pollen on the mother-])lant,
i. 430 ; on the fertilisation o{ Orchidece,
i. 434, 435 ; occasional necessary cross-
ing of plants, ii. 68 ; on seeds not
fitted for distribution, i. 330 ; potato-
grafting, i. 420 ; crossing of varieties,
ii. 83 ; on Primula sinensis and Oxalis
7'osea, ii. 113; on Corydalis cava, ii.
113,114.

Hill, R.. on the Alco, i. 32 ; feral
rabbits in Jamaica, i. 116; feral pea-
cocks in J.imaica, i. 200 ; variation of
the Guinea fowl in Jamaica, i. 310;
sterilitv of tamed birds in Jamaica,
ii. 138," 140.

Himalaya, range of gallinaceous birds
in the, i. 249.

Himalayan rabbit, i. 112, 113-115;
skull of, i. 125.

Himalayan sheep, i. 98.

HiNDMARSH, Mr., on Chillingham cattle,
i. 88.

« Hinkel-Taube," i. 149, 150.

Hinny and mule, difference of, ii. 43.

Hipparion, anomalous resemblance to, in
horses, i. 52.

Hippeastrum, hybrids of, ii. 120, 121.

Hive-bees, ancient domestication of, i.
313 ; breeds of, i. 314 ; smaller when

produced in old combs, ibid. ; varia-
bility in, i. 315 ; crossing of Liguriaa
and common, i'nd.

Hobbs, Fisher, on interbreeding pigs, ii.
100.

" Hocker-Taube," i. 148.

Hodgkix, Dr., on the attraction of foxes
by a female Dingo, i. 32 ; origin of
the Newfoundland dog, i. 44; trans-
mission of a peculiar lock of hair, i.
449.

Hodgson, Mr., domestication of Canis
primcevus, i. 27 ; development of a
tifth digit in Thibet mastiffs, i. 37 ;
number of ribs in humped cattle, i.
83 ; on the sheep of the Himalaya,
i. 98 ; presence of four mammae in
sheep, i. 99 ; arched nose in sheep,
i'lid. ; measurements of the intestines
of goats, 1. 106 ; presence of inter-
digital pits in goats, ibid. ; disuse a
cause of drooping ears, ii. 291.

HOFACKER, persistency of colour in
horses, i. 53, i. 464 ; production of
dun horses from parents of different
colours, i. 62 ; inheritance of peculi-
arities in handwriting, i. 450 ; heredity
in a one horned stag, i. 456 ; on
consanguineous marriages, ii. 103.

Hoffman, Prof, on Haphanus, i. 345.

Hog, Red River, ii. 133.

Hogg, Mr., retardation of breeding in
cows by hard living, ii. 90.

Holland, Sir H., necessity of in-
heritance, i. 446 ; on hei*editary
diseases, i 451 ; hereditary pecu-
liarity in the eyelid, i. 452 ; morbid
uniformity in the same family, i. 459 ;
transmission of hydrocele through
the female, ii. 27 ; inheritance of
habits and tricks, ii. 389.

Holly, varieties of the, i. 384, 385 ;
bud-reversion in, i. 409; yellow-
berried, i. 462, ii. 216.

Hollyhock, bud-variation in, i. 402 ;
non-crossing of double varieties of,
Ii. 85 ; lender variety of the, ii.
301.

Homer, notice of geese, i. 302; breed-
ing of the horses of ^neas, ii. 186.

Homologous parts, correlated varia-
bility of, ii. 314-325, 346, 347 ;
fusion of, ii. 333 ; affinity of, ii,
333, 334.

HOOFS.

INDEX.

HUTH.

459

Hoofs, correlated with hair in varia-
tion, ii. 318.

Hook-Billed duck, skull figured, i.
297.

Hooker, Dr. J. D., forked shoulder-
stripe in Syrian asses, i. 67 ; voice of
the cock in Sikkim, i. 272 ; use of
Arum-roots as food, i. 324; native
useful plants of Australia, i. 328 ;
wild walnut of the Himalayas, i.
379; variety of the plane-tree, i.
386 ; production of Thuja orientalis
from seeds of T. pendula, ihid. ;
singular form of Be<jonia frigidi, i.
389 ; reversion in plants run wild,
ii. 7 ; on the sugar-cane, ii. 153 ; on
Arctic plants, ii. 244 ; on the oak
grown at the C;ipe of Good Hope, ii.
204 ; on Rhododendron ciliat"m, ii.
267 ; stock and mignonette perennial
in Tasmania, ii. 295.

HoPKiRK, Mr., bud-variation in the
rose, i. 406 ; in Mirabilis jalapa, i.
407 ; in Convohuus tricolor, i. 440.

Hornbeam, heterophyllous, i. 385.

Horned fowl, i. 241 ; skull figured, i.
279.

Hornless cattle in Paraguay, i. 92.

Horns of sheep, i. 98 ; correlation of,
with fleece in sheep, ii. 318 ; corre-
lation of, with the skull, ii. 327 ;
rudimentary in young polled cattle,
ii. 306 ; of goats", i. I<i6.

Horses, in Swiss lake-dwellings, i. 51 ;
diti'erent breeds of, in Malay Archi-
pelago, ihid. ; anomalies in osteology
and dentition of, i. 52 ; mutual
fertility of different breeds, i. 53 ;
feral, i. 54; habit of scraping away
snow, i. 56 ; mode of production of
breeds of, i. 57 ; inheritance and
diversity of colour in, i. 58 ; dark
stripes in, i. 58-63, ii. 343 ; dun-
coloured, origin of, i. 61 ; colours of
feral, i. 63, 64 ; effect of fecundation
by a quagga on the subsequent pro-
geny of, i. 435 ; inheritance of pecu-
liarities in, i. 454, 456 ; polvdactylism
in, i. 459 ; inheritance of colour in,
i. 465 ; inheritance of exostoses in
legs of, i. 469 ; reversion in, ii. 6,
15 ; hybrids of, with ass and zebra,
li. 16; prepotency of transmission in
the sexes of, ii. 40 ; segregation of.

in Paragu;\y, ii. 80; wild species of,
breeding in captivity, ii. 132 ; curly,
in Paraguay, ii. 189, 318; selection
of, for trifling characters, ii. 195;
unconscious selection of, ii. 197, 198 ;
natural selection in Circassia, ii. 210 ;
alteration of coat of, in coal-mines,
ii. 268 ; degeneration of, in the Falk-
land Islands, ii. 267 ; diseases of,
caused by shoeing, ii. 290 ; feeding
on meat, ii. 294; white and white-
spotted, poisoned by mildewed vetches,
ii. 331 ; analogous variations in the
colour of, ii. 341 ; teeth developed on
palate of, ii, 385 ; of Bronze period
in Denmark, ii. 423.

Horse-chestnct, early, at the Tuileries,
i. 386 ; tendency to doubleness in, ii.
152.

Horse-radish, general sterility of the,
ii. 154.

"HouDAN," a French sub-breed of
fowls, i. 241.

Howard, C, on an Egyptian monument,
i. 17 ; on crossing sheep, ii, 73,
99,

Hue, on the Emperor Khang-hi, ii,
189 ; Chii.ese varieties of the bam-
boo, ii, 243,

Humboldt, A., character of the Zam-
bos, ii. 21 ; parmt speaking in the
language of an extinct tribe, ii, 138;
on Fulex penetrans, ii. 265.

Humidity, injurious effect of, upon
horses, i. 55.

Humphreys, Col., on Ancon sheep, i.
104.

Hungarian cattle, i. 84,

Hunter, John, period of gestation in
the dog, i, 30; on secondary sexual
characters, i, 188 ; fertile crossing
of Ayiser ferus and the domestic
goose, i. 3o3 ; inheritance of pecu-
liarities in gestures, voice, &c., i. 450 ;
assumption of male characters by
the human female, ii. 26 ; period of
appearance of hereditary diseases, ii,
54 ; graft of the spur of a cock upon
its comb, ii. 286 ; on the stomach of
Larus iridentatw!, ii. 292.

Hunter, W., evidence against the in-
fluence of imagination upon the
offspring, ii. 251.

Huth, Mr., close interbreeding of rabbits

160

HUTTON.

INDEX.

INHERITANCE.

ii. 100 ; consanguineous marriases,
103.

IIUTTON, Capt., on the variability of
the silk moth, i. 320 ; on the number
of species of silkworms, i. 310 ;
markicgs of silkworms, 1. 318; do-
mestication of the rock-pigeon in
ludia, i. 194; domestication and
crossing of Gallus bankiva, i. 248 ;
reversion in goats from a cross, ii.
19.

Hutchinson, Col., liability of dogs to
distemper, i. 37.

HuxLKY, Prof., on the transmission of
polydiictylisra, i. 457 ; on unconscious
selection, ii. 178 ; on correlation in
the mollusca, ii. 312; on gemmation
and fission, ii. 351 ; development of
star-fishes, ii. 362.

Hyacinths, i. 394-39G ; bud-variation
in, i. 411 ; graft-hybrid by union of
half bulbs of, i. 419 ; white, repro-
duced by seed, i. 463; red, ii. 215,
330 ; varieties of, recognisable by
the bulb, ii. 238.

Hyacinth, feather, ii. 169, 306.

Hyacinthus orientalis, i. 394.

Hybiscus syriacus, ii. 277.

Hybrids, of hare and rabbit, i. 109 ;
of various species of Gallus, i. 245-
248 ; of almond, peach, and nectarine,
i. 359 ; naturally produced, of species
of Cytisus, i. 413 ; from twin-seed of
Fuchsia coccinea hnd ful lens, i. 426;
reversion of, i. 425, 426, ii. 9, 22-24 ;
from mare, ass, and zebra, ii. 16 ; of
tame animals, wildness of, ii. 19, 20;
female instincts of sterile male, ii.
27 ; transmission and blending of
characters in, ii. 69-73 ; breed better
with parent species than with each
other, ii. 112; self-impotence in, ii.
119-121; readily produced in cap-
tivity, ii. 133.

Hybridisation, singular effects of, in
oranges, i. 357 ; of cherries, 1. 369 ;
ditficulty of, in Cucurbitce, i. 381 ;
of roses, i. 390.

Hyrridism, ii. 162-165; the cause of
a tendency to double flowers, ii. 156 ;
in relation to Pangenesis, ii. 381.

Hybridity in cats, i. 46, 47 ; supposed,

of peach and nectarine, i. 363.
Hydra, i. 398, ii. 283, 352.

Hydrangea, colour of flowers of, in-
fluenced by alum, ii. 267.
Hydrockle, ii. 27.
Hydrocephalus, ii. 285.
Hypericum calycinum, li, 1 54.
Hypericum crispum, ii. 212, 331.
Hypkrmetamorphosis, ii. 363.
Hypermetropia, hereditary, i. 452.

Ichthyo PTERYGIA, number of digits
in the, ii. 16.

Hex aquifulium, i. 462.

Imagination, supposed effect of, on
offspring, ii. 251.

Imntophyllum miniatum, bud-variation
in, i. 411.

Incest, abhorred by savages, ii. 103.

Incubation, by crossed fowls of non-
sitting varieties, ii. 18.

India, striped horses of, i. 61 ; pigs of,
i. 69, 80 ; breeding of rabbits io, i.
116; cultivation of pigeons in, i.
215.

Individual variabilitv in pigeons, i
166-168.

Ingledew, Mr., cultivation of Euro-
pean vegetables in India, ii. 153.

"Indische Taube," i. 151.

Inheritance, i. 445-473, ii. 306-369,
396 ; doubts entertained of, by
some writers, i. 446 ; importance of,
to breeders, i. 446, 447 ; evidence of,
derived from statistics of chances, i.
449 ; of peculiarities in man, i. 449-
451, 457-460 ; of di.sea.se, i. 451, 452,
460 ; of peculiarities in the eye, i. 452-
454; of deviations from symmetry,
i. 457 ; of polydactylism, i. 457-460 ;
capriciousness of, i. 460-465 ; of raiiti-
lations, i. 466 ; of congenital monstro-
sities, ibid.; causes of absence of, i. 467-
472 ; by reversion or atavism, ii. 1-
36 ; its connection with fixedness of
character, ii. 37-39 ; affected by pre-
potency of transmission of character,
ii. 40-47 ; limited by sex, ii. 47-51 ; at
corresponding periods of life, ii. 51—
57 ; summary of the subject of, ii. 57-
61 ; laws of, the same in seminal and
bud varieties, i. 442 ; of characters
in the horse, i. 53 ; in cattle, i. 90 ;
in rabbits, i. Ill ; in the peach, i. 360 ;
in the nectarine, ibid.; in plura.s, i.
368 ; in apples, i. 372 ; in pears.

INSANITY.

INDEX.

JUAN DE NOVA.

461

ibid. ; in the pansy, i. 393 ; of pri-
mary characters of Columba licia in
crossed pigeons, i, 21 i; of pecu-
liarities of plumage in pigeons, i. 1G9,
170; of peculiarities of foliage in
trees, i. 385 ; effects of, in A-arieties
of the cabbage, i. 344.
Insanity, inheritance of, i. 451, ii.

55.
Insects, regeneration of lost parts in, i.
358, ii. 284 ; agency of, in fecundation
of larkspurs, i. 464 ; etfect of changed
conditions upon, ii. 141 ; sterile
neuter, ii. 171 ; monstrosities in, ii.
257, 385

Instincts, defective, of silkworms, i.
320.

Interbreeding, close, ill effects of, ii.
92-111, 159.

Intercrossing, of species, as a cause of
variation, i. 197; natural, of plants,
1. 356 ; of species of Canidae and
breeds of dogs, i. 32-34 ; of domestic
and wild cats, i. 46, 47 ; of breeds of
pigs, i. 74, 81 ; of cattle, i. 86; of
varieties of cabbage, i. 343 ; of peas,
i. 345, 348, 349 ; of varieties of
orange, i. 357 ; of species of straw-
berries, i. 373, 374; of Cuairbitce, i.
380, 381 ; of flowering plants, i. 388 :
of pansies, i. 392.

Interdigital pits, in goats, i. 106.

Intermarriages, close, ii. 102, 103.

Intestines, elongation of, in pigs, i.
77 ; relative measurement of parts
of, in goats, i. 106 ; eff'ects of changed
diet on, ii. 292.

fpoinoca purpurea, ii. 108.

Ireland, remains of Bos frontosus and
longifrons found in, i. 85.

Iris, hereditary absence of the, i. 454 ;
hereditary peculiarities of colour of
the, ibid. ; variation of, i. 412.

7m xiphium, i. 412.

Irish, ancient, selection practised by
the, ii. 187.

Iron period, in Europe, dog of, i. 18.

Islands, oceanic, scarcity of useful
plants on. i. 328.

ISLAY, pigeons of, i. 193.

Isolation, effect of, in favour of selec-
tion, ii. 219, 220.

Italy, vine-growing in, during the
Bronze period, i. 352.

Ivy, sterility of, in the north of Europe,
ii. 154.

Jack, Mr., effect of foreign pollen on

grapes, i. 430.
Jackal, i. 25, 28, 31 ; hybrids of, with
the dog, i. 33 ; pi epotency of, over
tho dog, ii. 43.
Jackson, Mr., white-footed cats, ii

316.
Jacobin pigeon, i. 161, 218.
Jacquemet-Bonnefort, on the mul-
berry, i. 354.

Jaeger, Prof., on reversion in pigs,
from a cross, ii. 17 ; white pigeons
killed by hawks, ii. 215.

Jaguar, with crooked legs, i. 17.

Jamaica, feral dogs of, i. 28; feral
pigs of, i. 80 ; feral rabbits of, i. 116.

Jameson, Mr., on hybrid potatoes, i.
421.

Japan, horses of, i. 56.

Japanese pig (figured), i. 72.

Jardine, Sir W., crossing of domestic
and wild cats, i. 46.

Jarves, J., silkworm in the Sandwich
Islands, i. 318.

Java, fantail pigeon in, i. 155.

Javanese ponies, i. 56, 61.

Jeitteles, history of the dog, i. 15 ;
history of the fowl, i. 258 ; Hun-
gai'ian sheep-dogs, i. 24 ; crossing of
domestic and wild cats, i. 46.

Jemmy Button, i. 326.

Jenyns, L., whiteness <>f ganders, i.
303 ; sunfish-like variety of the
goldfish, i. 313.

Jerdon, J. C, number of eggs laid by
the pea-hen, ii. 191 ; origin of
domestic fowl, i. 248.

Jersey, aborescent cabbages of, i. 341.

Jessamine, i. 418.

Jesse, G. R., on the bulldog, i. 44.

John, King, importation of stallions
from Flanders by, ii. 187.

Johnson, D., occurrence of stripes on
young wild pigs in India, i. 80.

Jordan, A., ou Vibert's experiments on
the vine, i. 352 ; origin of varieties
of the apple, i. 372 ; varieties of
pears found wild in woods, ii. 247.

Jourdan, parthenogenesis in the silk-
moth, ii. 357.

Jtian de Kova, wild dogs on, i. 27

i62

JTAN.

INDEX.

KKOPF-TAUBEN.

Juan Fernandez, dumb dogs on, i. 27.

Juglans regia, i. 379.

Jukes, Prof., origin of the Newfound-
land dog, i. 44.

JULIEN, Stanislas, early domestication
of pigs in China, i. 71 ; antiquity of
the domestication of the silkworm in
China, i. 316.

Jumpers, a breed of fowls, i. 241.

Juniper, variations of the, i. 385, 387.

Juniper-US suecica, i. 385.

Jussicea grandijiora, ii. 154.

JussiEU, A. de, structure of the pappus
m Carthanius, ii. 307.

Kail, Scotch, reversion in, ii. 5.
Kales, i. 341.

" Kali-par " pigeon, i. 149.
Kalm, p., on maize, i, 340, ii. 298 ; in-
troduction of wheat into Canada, i.

333 ; sterility of trees growing in

marshes and dense woods, ii. 154,
"Kalmi Lotan" tumbler pigeon, i.

157.
Kane, Dr., on Esquimaux dogs. i. 22.
Karakool sheep, i. 102.
Karkeek, on inheritance in the horse,

i. 455.
" Karmeliten Taube," i. 164.
Karsten on Pulex penetrans, ii. 265.
Kattywar horses, i. 61.
Keeley, R., pelorism in Galeobdolon

lutcum, ii. 33.
Kerner, on the culture of Alpine

plants, ii. 147 ; definite action of

conditions, ii. 271.
Kestrel, breeding in captivity, ii. 137.
" Khandesi," i. 147.
Khang-hi, selection of a variety of rice

by, ii. 189.
KlANG, ii. 17.

KiDD, on the canary-bird, i. 311, ii. 53.
Kidney bean, i. 396 ; varieties of, ii,

243, 265.
Kidneys, compensatory development

of the, ii. 290; shape of, in birds

influenced by the form of the pelvis,

ii. 336,
King, Col., domestication of rock doves

from the Orkneys, i. 193, 194.
King, Dr., on Faritium, i. 402.
King, P. P., on the dingo, i. 21, 28,
Kirby and Spence, on the growth of

galis, ii. 273.

Kirghisian sheep, i. 102.

Kite, breeding in captivity, ii. 137.

Kleine, variability of bees, i. 314.

Knight, Andrew, on crossing horses of
different breeds, i. 53 ; crossing varie-
ties of peas, i. 345, ii, 110; persis-
tency of varieties of peas, i. 348 ;
origin of the peach, i, 357 ; hybridi-
sation of the morello by the Elton
cherry, i. 368 ; on seedling cherries,
i. 369 ; variety of the apple not
attacked by coccus, i. 371 ; intercross-
ing of strawberries, i, 373, 374 ; broad
variety of the cock"s-comb, i, 389 ;
bud variation in the cherry and
plum, i, 399; crossing; of white and
purple grapes, i, 419; experiments
in crossing apples, i. 433, ii. 110;
hereditary disease in plants, i, 455 ;
on interbreeding, ii. 95 ; crossed
varieties of wheat, ii. 110; necessity
of intercrossing in -plants, ii. 159;
on variation, ii, 243, 244; effects of
grafting, i. 413, ii, 267 ; bud-varia-
tion in a plum, ii. 281 ; correlated
variation of head and limbs, 315.

Knox, Mr., breeding of the eagle owl
in captivity, ii. 137.

Koch, degeneracy in the turnip, i.
344.

Kohlrabi, i, 342.

KoLREUTER, reversion in hybrids, i,
425, ii. 9 ; acquired sterility of
crossed varieties of plants, i. 381,
ii, 79 ; absorption of Mirahilis vul-
garis by M. longijiora, ii. 65 ; crosses
of species of Verbascum, ii. 71, 85;
on the hollyhock, ii, 85 ; crossing
varieties of tobacco, ii. 87 ; benefits
of crossing plants, ii. 110, 111, 159,
160; selt-impotence in Verbascum, i.
118, 122; eflects of conditions of
growth upon fertility in Mira'nlis, ii.
147 ; great development of tubers
in hybrid plants, ii. 156 ; inheritance
of plasticity, ii, 227 ; variability of
hybrids of Mirab lis, ii, 253; repeated
crossing a cause of variation, ii, 254,
256 ; number of pollen-grains neces-
sary fur fertilisation, ii, 356.

" Krauseschwein," i. 70.

Krohn, on the double reproduction o£
Medusas, ii, 379,

" Kropf-Tadben," i. 143.

LABAT.

INDEX.

LEGUAT.

463

Labat, on the tusks of feral boars in

the West Indies, i. 180 ; on French

wheat grown in the West ladies, ii.

297 ; on the culture of the viae in

the West Indies, ii. 298.
Laburnum, Adam's, see Cytis'is adami ;

oak-leaved, reversion of, i. 408 ; pelo-

rism in the, ii. 338; Waterer's, i. 416.
Lachmann, on gemmation and fission,

ii. 351.
Lachnanthes tinctoria, ii. 212, 330.
Lactation, imperfect, hereditary, i.

452 ; deficient, of wild animals in

captivity, ii. 142.
Ladrone Islands, cattle of, i. 89.
La Gasca, Prof., individual variation in

wheat, i. 332.
Laing, Mr., resemblance of Norwegian

and Devonshire cattle, i. 85.
Lake-dwellings, sheep of, i. 98, ii.

423 ; cattle of, ibid. ; absence of

the fowl in, i. 258 ; cultivated plants

of, i. 337, ii. 423, 424 ; cereals of, i.

335-337 ; peas found in, i. 345 ;

beans found in, i. 349.
Lamare-piquot, observations on half-
bred North American wolves, i. 22.
Lambert, A. B., on Thuja pendula or

filiformis, i. 386.
Lambert family, i. 448, ii. 53.
Lambertye, on strawberries, i. 373,

374 ; five-leaved variety of Fragaria

coUina, i. 375.
Landt, L., on sheep in the Faroe

Islands, ii. 81.
Lankester, Ray, on longevity, ii. 376.
La Plata, wild dogs of, i. 28 ; feral

cat from, i. 49.
Larch, ii. 301.
Larkspurs, insect agency necessary for

the full fecundation of, i. 464.
Larus argerdatus, ii. 141, 292.
Larus fridactg/us, ii. 292.
Lasterye, merino sheep in different

countries, i. 103.
Latent characters, ii. 25-31.
Latham, on the fowl not breeding in

the extreme north, ii. 144.
Lath ,rus, ii. 11.
Lathjirus aphaca, ii. 335.
Lathgrus uduratuSy \, 426, 463, ii. 68, 71,

302,
La TouCHE, J. D., on a Canadinn apple

with dimidiate fruit, i. 425, 426.

" Latz-Taube," i. 162.

Laugher pigeon, i. 163, 217.

/.aurus sassafras, ii. 264.

Lawrence, J., production of a new
breed of foxhounds, i. 42 : occurrence
of canines in mares, i. 52 ; on three-
parts-bred horses, i. 57 ; on inheri-
tance in the horse, i. 454, 455.

Lawson, Mr,, varieties of the potato, i.
350.

Laxton, Mr., bud-variation in ths
gooseberry, i. 4U0 ; crossing of
varieties of the pea, i. 428, 429 ;
weakness of transmission in peas, ii.
42 ; double-flowered peas, ii. 152.

Layard, E. L., resemblance of a Caffre
dog to the Esquimaux breed, i. 26, ii.
276 ; crossing of the domestic cat
with Felis caffra, i. 46 ; feral pigeons
in Ascension, i. 200 ; domestic pigeons
of Ceylon, i. 215; on Gallus stanlegi,
i. 246 ; on black-skinned Ceylonese
fowls, i. 269.

Le Compte family, blindness inherited
in, ii. 54.

Lecoq, bud-variation in Ifirabilisjalapa,
i. 407 ; hybrids of Mirabilis, i. 426,
ii. 153, 253 ; crossing in plants, ii.
108; fecundation of /"assiyfo/'a, ii. 118 ;
hybrid Gladiolus, ii. 121 ; sterility of
Lanunculus fcaria, ii. 154 ; villosity in
plants, ii, •_67 ; double asters, ii. 307.

Le Couteur, J., varieties of wheat, i.
331-334; acclimatisation of exotic
wheat in Europe, i. 333 ; adaptation
of wheat to soil and climate, i'lid. ;
selection of seed-corn, i. 335 ; evil from
inter-breeding, ii. 101 ; on change of
soil, ii. 129; selection of wheat, ii.
184; natural selection in wheat, ii.
218 ; cattle of Jersey, ii. 220.

Ledger, Mr., on the llama and alpaca,
ii. 193.

Lee, Mr., his early culture of the pansy,
L 391.

Leersia orgzoidc^, ii. 69.

Lefour, period of gestation in cattle, i.
90.

Legrain, fiilsified experiments of, ii.lOO

Legs, of fowls, eflects of disuse on, i.
284-287 ; characters and variations
of, in ducks, ii. 299-302.

Leguat, cattle of the Cape of Good
Hope, i. 91.

i6i

LEHMANN.

INDEX.

LIVINGSTONE.

Lehmann, occurrence of wildrdouble-

flowe:ed plants near a hot spring, ii.

132.
Leigrton, W. a., propagation of a

weeping yew by seed, i. 461.
Leitner, eflects of removal of anthers,

ii. 151.
Lemming, ii. 135.
Lemoine, yaiiegated Symphytum and

Phlox, i. 410.
Lemon, i. 355, 356 ; orange fecundated

by pollen of the, i. 430.
Lemurs, hybrid, ii. 136.
Leporides, ii. 135.
Lepsius, figures of ancient Egyptian

dogs, i. lY ; domestication of pigeons

in ancient Egypt, 214.
Lepus glacial is, i. 116.
Zepus magellanicus, i. 117.
Lepus ni tripes, i. 113.
Zepus tibctanus, i. 116.
Zepus variabilis, i. 115.
Lereboullet, double monsters of fishes,

ii. 333.
Leslie, on Scotch wild cattle, i. 88.
Lessona, on re-growth, ii. 358 ; on

Zepus magellanicus, i. 117.
Lethbridge, previous impregnation, i.

435.
Leuckart, on the lai-va of Cocidomyidse,

ii. 353.
Lewes, G. H., on Pangenesis, ii. 350.
Lewis, G., cattle of the West Indies, ii.

214.
Lherbette and Quatrefages, on the

horses of Circassia, ii. 80, 210.
Lichens, sterility in, ii. 155.
LiCilENSTEiN, resemblance of Bosjes-

man's dogs to Canis mesomelas, i. 26 ;

Newfoundland dog at the Cape of

Good Hope, i. 37.
LiEBiG, differences in human blood, ac-
cording to complexion, ii. 265.
LlEBREiCH, occurrence of pigmentary

retinitis in deaf-mutes, ii. 322.
Lilacs, ii. 148.

LlLiACE^, contabescence in, ii. 149.
Zilium bulbiferum and davuricum, i. 431.
Zilium candidum, ii. 118.
Limbs, regeneration of, ii. 370.
Limbs and head, correlated variation of,

ii. 315.
Lime, e^ect of, upon shells of the mol-

lusca, ii. 270.

Lime-tree, changes of, by age, i. 387-
413.

Limitation-, sexual, ii. 47-51.

Limitation, supposed, of variation, ii.
412.

Zinaria, pelorism in, ii. 32, 35, 38; pe-
loric, crossed with the normal form,
ii. 46 ; sterility of, ii. 150.

Zinaria vulgaris and purpurea, hybrids
of, iL 72.

LiNDEMUTH, potato-grafting, i. 422.

LiNDLEY, John, classification of varie-
ties of cabbages, i, 342 ; origin of the
peach, i. 357 ; influence of soil on
peaches and nectarines, i. 360 ; varie-
ties of the peach and nectarine, i.
364 ; on the New Town pippin, i.
870; freedom of the Winter Majetin
apple from coccus, ibid.; pro<luctioa
of monoecious Hautbois strawberries
by bud-selection, i. 375 ; origin of
the large tawny nectarine, i. 399 ;
bud-variation in the gooseberry, i.
400 ; hereditary disease in plants, i.
455 ; on double flowers, ii. 151 ;
seeding of ordinarily seedless fruits,
ii. 152 ; sterility of Acorus calamus,
ii. 154 ; resistance of individual plants
to cold, ii. 299.

LlNN.^US, summer and winter wheat
regarded as distinct species by, i.
333 ; on the single-leaved straw-
berry, i. 375; sterility of Alpine
plants in gardens, ii. 147 ; recognition
of individual reindeer by the Lap-
landers, ii. 238 ; growth of tobacco
in Sweden, iL 298.

Linnet, ii. 141.

Zinota cannabina, ii. 141.

Jjinum, ii. 149.

Lion, fertility of, in captivity, ii. 133,
134.

Lipari, feral rabbits of, i. 118.

Livingstone, Dr., striped young pigs
on the Zambesi, i. 80 ; domestic rab-
bits at Loanda, i. 116 ; use of grass-
seeds as food in Africa, i. 326 ; plant-
ing of fruit-trees by the Batokas, i.
326; character of half-castes, ii. 21 ;
taming of animals among the Barotse,
ii. 144; selection practised in South
Africa, ii. 191, 194.

Livingstone, Mr., disuse a cau.so ol
drooping ears, ii. 291.

LIZARDS.

INDEX.

LUCAS.

465

Lizards, reproduction of tail in, ii. 284. }

Llama, selection of, ii. 192.

Llovd, Mr., taming of the wolf, i. 27;
English dogs in northern Europe, i.
37 ; fertility of the goose increased
by domestication, i. 303 ; number of
eggs laid by the wild goose, ii. 91 ;
breeding of the capercailzie in cap-
tivity, ii. 139.

Loanda, domestic rabbits at, i. 116.

Loasa, hybrid of two species of, ii. 76.

Lobelia, reversion in hybrids of, i. 425 ;
contabescence in, ii. 149.

Lobelia fulgens, cardinalls, and syphili-
tica, ii. 117,

Lockhart, Dr., on Chinese pigeons, i.
216.

Locust-tree, ii. 264.

Loiseleur-Dhslongchamps, origi nals
of cultivated plants, i. 324 ; Mon-
golian varieties of wheat, i. 331 ;
characters of the ear in wheat, ibid. ;
acclimatisation of e.\otic wheat in
Europe, i. 332 ; effect of change of
climate on wheat, i. 334 ; on the sup-
posed necessity of the coincident
variation of weeds and cultivated
plants, i. 335 ; advantage of change
of soil to plants, ii. 128.

Lolinm ternulentum, variable presence
of barbs in, i. 331.

Long-tailed sheep, i. 98.

LOOCHOO Islands, horses of, i. 56.

Lord, J. K., on Canis latrans, i. 22.

" LORI RAJAH," how produced, i. 269,

Lorius garrulus, ii. 269,

•' LOTA^ " tumbler pigeon, i. 157,

Loudon, J, W., varieties of the carrot,
i, 345 ; short duration of varieties of
peas, i. 348 ; on the glands of peach-
leaves, i. 364 ; presence of bloom on
Russian apples, i. 370 ; origin of
varieties of the apple, i, 372 ; varie-
ties of the gooseberry, i. 376 ; on
the nut tree, i. 379 ; varieties of the
ash, i. 384 ; fastigate juniper (.7.
succica), i. 385 ; on Ilex wjuifolium
ferox, ibid. ; varieties of the Scotch
fir, i, 386, 387 ; varieties of the
hawthorn, i, 387 ; variation in the
persistency of leaves on the elm and
Turkish oak, i, 386 ; importance of
cultivated varieties, i. 387; varieties
of Eosa spinosissima, i. 391 ; variation

of dahlias from the same seed, i, 394;
production of Provence roses from
seeds of the moss rose, i, 405 ; eff'ect
of grafting the purple-leaved upon
the common hazel, i, -119; inter-
crossing melons, ii. 110; nearly
evergreen Cornish variety of the elm,
ii. 301,

Low, G., on the pigs of the Orkney
Islands, 1. 74.

Low, Prof, pedigi-ees of greyhounds, i,
447 ; origin of the dog, i. 16 ; bur-
rowing instinct of a half-bred dingo,
i. 28 ; inheritance of qualities in
horses, i, 53 ; comparative powers of
English race-horses, Arabs, &c,, i, 57 ;
British breeds of cattle, i. 83; wild
cattle of Chartley, i. 88 ; effect of
abundance of food on the size of
cattle, i. 95 ; effects of climate on the
skin of cattle, i. 96, ii. 319 ; on inter-
breeding, ii. 95 ; selection in Hereford
cattle, iL 199 ; formation of new
breeds, ii. 231 ; on " sheeted" cattle,
ii. 341.

Lowe, Mr., on hive bees, i. 316.

Lowe, Rev. Mr., on the range of Pyrus
7nalus and P. acerba, i. 370.

LowNE, Mr., monsters, ii. 333 ; on
gemmules, ii, 372.

" Lowtun" tumbler pigeon, i. 157.

Loxia pyrrhnla, ii. 137,

Lubbock, Sir J., developments of the
Ephemeridae, ii, 361,

Lucas, P., effects of cross-breeding on
the female, i. 436 ; hereditary diseases,
i. 451, ii. 54, 55 ; hereditary affections
of the eye, i. 453, 454 ; inheritance of
anomalies in the human eye and in
that of the horse, i. 454 ; inheritance
of polydactylism, L 458 ; morbid
uniformity in the same family, i,
459 ; inheritance of mutilations, i.
469 ; persistency of cross-reversion,
ii, 9 ; persistency of character in
breeds of animals in wild countries,
ii. 39 ; prepotency of transmission, ii.
40, 44 ; supposed rules of trans-
mission in crossinsT animals, ii. 44 :

O 7 7

sexual limitations of transmission of
peculiarities, ii. 48, 49 ; absorption of
the mmority in crossed races, ii. 65 ;
crosses without blending of certain
characters, ii. 69 ; on interbreeding,

^66

LUCAZB.

INDEX.

MABCEL.

ii. 95 ; variability dependent on re-
production, ii. 237 ; period of action
of variability, ii. '247 ; inheritance of
deafness in cats, ii. 322 : complexion
and constitution, ii. 329.

LUCAZE - DiJTHiERS, structure and
growth of galls, ii. 272-274.

LuCAE, Prof., on the masked pig, i. 72;
on pigs, ii. 289.

LuiZET, grafting of a peach-almond on
a peach, i. 359.

LiJTKE, cats of the Caroline Archipelago,
i. 49.

Luxuriance, of vegetative organs, a
cause of sterility in plants, ii. 152,
155.

Lyonnet, on the scission of Xais, ii. 351.

Lysimachia nummularia, sterility of, ii.
154.

Lythrum, trimorphic species of, ii. 394.

Lythrum sal ''carta, ii. 166 ; contabescence
in, ii. 149.

Lytta vesicatoria, affecting the kidneys,
ii. 373.

Macacus, species of, bred in captivity,
ii. 135.

Macaulay, Lord, improvement of the
English horse, ii. 197.

M'Clelland, Dr., variability of fresh-
water fishes in India, ii. 246.

M'COY, Prof., on the dingo, i. 26.

Macfayden, influence of soil in pro-
ducing sweet or bitter oranges from
the same seed, i. 355.

Macgillivray, domestication of the
rock-dove, i. 194; feral pigeons in
Scotland, i. 200 ; number of vertebra
in birds, i. 280 ; on wild geese, i.
302 ; number of eggs of wild and tame
ducks, ii. 91.

Mackenzie, Sir G., peculiar variety of
the potato, i. 350.

Mackenzie, P., bud-variation in the
currant, i. 400.

MACKINNON, Mr., horses of the Falkland
Islands, i. 55 ; feral cattle of the
Falkland Islands, i. 89.

MacKnight, C, on interbreeding cattle,
ii. 90.

MacNab, Mr., on seedling weeping
birches, i. 461; non-production of
the weeping beech by seed. i. 462.

Madagascar, cats of, i. 49,

Madden, H., on interbreeding cattle,
ii. 96.

Madeira, rock pigeon of, i. 193.

Mi.gnolia g7\xndijiora, ii. 299.

Magnus, Herr, on potato-grafting, i
422 ; on graft-hybrids, i. 423, 424.

Maize, its unity of origin, i. 338; anti-
quity of, ibid. ; with husked grains
said to grow wild, ibid.; variation of,
i. 239 ; irregularities in the flowers
of, i. 339 ; pei'sisteuce of varieties,
ibid.; adaptation of, to climate, i.
340, ii. 297 ; acclimatisation of, ii,
304, 339 ; crossing of, i. 430, ii. 82,
83 ; extinct Peruvian varieties of, ii
421.

Malay fowl, i. 237.

Malay Archipelago, horses of, i. 56 ;
short-tailed cats of, i. 49 ; striped
young wild pigs of, i. 80 ; ducks of,
i. 294.

Male, influence of, on the fecundated
female, i. 428-437 ; supposed influence
of, on ortspring, ii. 44.

Male flowers, appearance of, among
female flowers in maize, i. 339.

Malformations, hereditary, n. 55.

Malingie-Nouel, on sheep, i. 100;
cross-breeding sheep, ii. 45; English
sheep in France, ii. 220.

Malm, eyes of flat fish, ii. 28.

Malva, fertilisation of, i. 434, ii. 356.

Alamestra suasu, ii. 141.

Mamm^, variable in number in the pig,
i. 77 ; rudimentary, occasional full
development of, in cows, i. 91, ii.
309; four present in some sheep, i.
99 ; variable in number in rabbits,
i. 110; latent functions of, in male
animals, ii. 27, 309.

Mangles, Mr., annual varieties of the
heartsease, ii. 295.

Mantegazza, abnormal growth of spur
of cock, ii. 365 ; on Pangenesis, ii.
371.

Mantell, Mr., taming of birds by the
New Zealanders, ii. 144.

Manu, domestic fowl noticed in the In-
stitutes of, i. 258.

Manure, etfect of, on the fertility of
plants, ii. 147.

Manx cats, i. 48, ii. 41.

Marcel de Serres, fertility of the os-
trich, ii. 140.

MARIANNE.

INDEX.

MEMBRANES.

467

Mauianne Islands, varieties of Fan-
danus in, ii. 24-3.

Mark ham, Gervase, on i-abbits, i. 108,
ii. 188.
, Markhor, probably one of the parents
of the goat, i. 105.

Marquaxd, cattle of the Channel
Inlands, i. 84.

Marrimpoey, inheritance in the horse,
i. 455.

JI ARROW, vegetable, i. 380.

Marryatt, Capt., breeding of asses in
Kentucky, ii. 223.

Marsdex, notice of Gallus giganteus, i.
246.

Marshall, Dr. W., on Gallus sonneratii,
i. 245.

Marshall, Mr., voluntary selection of
pasture by sheep, i. lOO; adaptation
of wheats to soil and climate, i. 334 ;
" Dutch-buttocked " cattle, i. 452 ;
S'igregation of herds of sheep, ii. 81 ;
advantage of change of soil to wheat
;ind potatoes, ii. 128; fashionable
change in the horns of cattle, ii. 195 ;
sheep in Yorkshire, ii. 221.

Martens, E. vox, on Acha'inella, ii.
28.

Martin, W. C. L., origin of the dog, i.
16; Egyptian dogs, i. 18; barking of
a Mackenzie River dog, i. 27 ; African
hounds in the Tower menagerie, i.
o3 ; on dun horses and dappled asses,
1. 58 ; breeds of the horse, i. 51 ; wild
Lorses, i. 53 ; Syrian breeds of asses,
1. 65 ; asses without stripes, i. 66 ;
effects of cross-breeding on the female
in dogs, i. 436 ; striped legs of mules,
ii. 16.

Martixs, defective instincts of silk-
Avorms, i. 321.

Martius, C, fruit-trees of Stockholm,
ii. 297.

Masox, W.. bud-variation in the ash, i.
408.

Masters, Dr., on bud-variation and
I'eversion, i. 403 ; potato-grafting,
i. 421 ; on pollen within ovule.s, ii.
387 ; reversion in the spiral-leaved
weeping willow, i. 408 ; on peloric
tlowers, ii. 32; on Opuntia, ii. 274;
pelorism in a clover, ii. 338 ; position
as a cause of pelorism, ii. 338, 339.

Masters, Mr., persistence of varieties

of peas, i. 348 ; reproduction of colour
in hyacinths, i. 463 ; on hollyhocks,
ii. 85 ; selection of peas for seed, ii.
184; on Hibiscus sgriacus, ii. 276 ; re-
version by the terminal pea in the
pod, ii. 340.

Mastiff, sculptured on an Assyrian
monument, i. 17, ii. 424; Tibetan, i.
37, ii. 268.

Matthews, Patrick, on forest trees, ii.
223.

Matthiola annua, i. 429, 463, ii. 71.

Matthiola incana, i. 407, 429.

Mauchamp merino sheep, i. 104.

Mauduyt, crossing of wolves and dogs
in the Pvrenees, i, 24.

IMauxd, Mr., crossed varieties of wheat,
ii. 110.

Madpertuis, axiom of " least action,'*
i. 13.

Mauritius, importation of goats into,
i. 105.

Maw, G., effects of change of climate,
ii. 300; correlation of contracted
leaves and flowers in pelargoniums,
ii. 324, 325.

Mawz, fertility of Brassica rapa, ii. 148.

MaxUlaria, self-fertilised capsules of, ii.
114.

MaxiUaria atro-rubens, fertilisation of,
by M. squalens, ii. 114.

Maxuiowicz, direct action of pollen, i.
431.

Mayers, on gold-fish in China, i. 312.

Mayes, M., self-impotence in Ainargllis,
ii. 120.

Meckel, on the number of digits, i.
458 ; correlation of abnormal muscles
in the leg and arm, ii. 314.

Medusa, development of, ii. 364, 379.

Meehax, Mr., weeping peach, i. 4(>1 ;
effects of parasites, ii. 275 ; compari-
son of European and American trees,
ii. 270.

3felc'S taxus, ii. 134.

Meloxs, i. 383, 384; mongrel supposed
to be produced from a twin-seed, i.
427 ; crossing of varieties of, i. 430,
ii. 86, 109; inferiority of, in Roman
times, ii. 200 ; changes in, by culture
and climate, ii. 264 ; serpent, correla-
tion of variations in, ii. 324; analo-
gous variations in, ii. 341.

Membranes, false, ii. 284, 285.

468

MENETRIES.

INDEX.

MOQUIN-TAKDON.

Menetuies, on the stomach of Strix
grallaria, ii. 292.

Meningitis, tubercular, inheriteil, ii. 55.

Merrick, potato-graftiag, i. 422.

Mepagenesis, ii. 362,

Mktamorphosis, ii. 362.

Metamorphosis and development, ii.
383, 384-.

Metzger, on the supposed species of
wheat, i. 329, 330; tendency of wheat
to vary, 1. 332 ; variation of maize, i.
839, 340 ; cultivation of American
maize in Europe, i. 340, ii. 339; on
cabbages, i. 341-344 ; acclimatisation
of Spanish wheat in Germany, i. 472 ;
advantage of change of soil to plants,
ii. 128; on rye, ii. 241; cultivation
of different kinds of wheat, ii. 248.

Mexico, dog from, with tan spots on
the eyes, i. 29 ; colours of feral horses
in, i. 64.

Meyen, on seeding of bananas, ii. 152.

Mice, grey and white, colours of, not
blended by crossing, ii. 70 ; rejection
of bitter almonds by, ii. 218; naked,
ii. 268.

Michaux, F., roan-coloured feral horses
of Mexico, i. 64 ; origin of domestic
turkey, i. 308 ; on raising peaches
from seed, i. 360.

Michel, F., selection of horses in mediae-
val times, ii. 1 87 ; horses preferred
on account of slight characters, li.
194.

MiCHELY, effects of food on caterpillars,
ii. 270 ; on Bumbyx hesperus, ii. 329.

Microphthalmia, associated with de-
fective teeth, ii. 321.

Middens, Danish, remains of dogs in, j.
18, ii. 423.

Mignonette, ii. 223, 301.

Millet, i. 396.

Mills, J., diminished fertility of mares
when first turned out to grass, ii.
145.

Milne-Edwards, on the development
of the Crustacea, ii. 363.

Milne-Edwards, A., on a crustacean
with a monstrous eye-peduncle, ii.
335.

Milvus niget% ii. 137.

Mimulus luteus, ii. 109.

Minor, W. C, gemmation ind fi.>;sion in
annelids, ii. 351.

Mirahilis, fertilisation of, ii. 356 ; hybrids
of, ii. Ill, 153, 253.

Mirahilis jalapa, i. 407, 426.

Mirahilis longiflora, ii. 65.

Mirah'dis vidijaris^ ii. 65.

Misocampus and Cecidomnia, i. 5.

Mitchell, Dr., efiects of the poison of
the rattlesnake, ii. 279.

Mitford, Ml-., notice of the breeding of
horses by Erichthonius, ii. 186.

MiVART, Mr., rudimentary organs, ii.
308.

MocCAS Court, weeping oak at, i. 461.

MOGFORD, horses poisoned by fool's par-
sley, ii. 331.

MoLLER, L., effects of food on insects,
ii. 270.

Mole, white, ii. 326.

Moll and Gayot, on cattle, i. 84, ii. 74,
195.

Mollusc A, change in shells of, ii. 270.

Monke, Lady, culture of the pansy by,
i. 391.

Monkeys, rarely fertile in captivity,
ii. 135.

MONNIER, identity of summer and
winter wheat, i. 333.

Monsters, double, ii. 333, 334.

Monstrosities, occurrence of, in do-
mesticated animals and cultivated
plants, i. 389, ii. 241 ; due to per-
sistence of embryonic conditions,
ii. 31 ; occurring by reversion, ii.
31-34; a cause of sterility, ii. 150,
151 ; caused by injury to the embryo,
ii. 257.

Moor, J. H., deterioration of the horse
in Malasia, i. 56.

MoORCROFT, Mr., on Hasora wheat, i.
331 ; selection of white-tailed yaks,
ii. 190; melon of Kaschmir, ii. 264;
varieties of the apricot cultivated in
Ladakh, i. 366 ; varieties of the
walnut cultivated in Kaschmir, i.
379.

MoORE, Mr., on breeds of pigeons, i.
155, 163, 217, 219, 221; on ground
tumblers, i. 228.

MoORUK, fertility of, in captivity, ii.
140.

Moquin-Tandon, original form of
maize, i. 339 ; variety of the double
columbine, i. 389 ; peloric flowers,
ii. 32—35; position as a cause ol

MOKLOT.

INDEX.

NARCISSUS.

469

pelorism in flowers, ii. 337 ; tendency
of peloric flowers to become irregulai*,
ii. 46 ; on monstrosities, ii. 241 ;
correlation in the axis and appen-
dages of plants, ii. 312 ; fusion of
homologous parts in plants,' ii. 333-
335 ; on a bean with monstrous
stipules and abortive leaflets, ii.
335 ; conversion of parts of flowers,
ii. 387.

MoRLOT, dogs of the Danish Middens,
i. 18 ; sheep and horse of the Bronze
period, ii. 423.

Mormodes ignea, ii. 28.

Morocco, estimation of pigeons in, i.
215.

MoRREN, grafts of Abutilon, i. 418;
on pelorism, ii. 33 ; in Calceolaria,
ii. 338 ; non-coincidence of double
flowers and variegated leaves, ii.
151.

Morris, Mr., breeding of the kestrel in
captivity, ii. 137.

Morse, Dr. digits of birds, ii. 315.

MortoK, Lord, effect of fecundation
bv a quagga on an Arab mare, i.
435.

Morton, Dr.. origin of the dog, i. 16.

Morus alba, i. 354.

Moscow, rabbits of, i. Ill, 125 ; effects
of cold on pear-trees at, ii. 297.

Mosses, sterility in, ii. 155 ; retro-
gressive metamorphosis in, ii. 354.

Moss-rose, probable origin of, from
liosa centifolia, i. 405 ; Provence
roses produced from seeds of, ibid.

MosTO, Cada, on the introduction of
rabbits into Porto Santo, i. 117.

MoT-MOT, mutilation of feathers in-
herited, i. 470.

Mottling of fruits and flowers, i. 430.

Mountain-ash, ii. 216.

Mouse, Barbary, ii. 135.

" Moven-taube," i. 156.

Mowbray, Mr., on the eggs of game
fowls, i. 261 ; early pugnacity of
game cocks, i. 263 ; diminished fe-
cundity of the pheasant in captivity,
ii. 139.

Mowbray, Mr., reciprocal fecundation
of Passijiora alata and racerno>>a, ii.
118.

Mulattos, character of, ii. 21.

Mulberry, i. 354, ii. 243.

42

Mule and hinny, differences in the, ii.
43.

Mules, striped colouring of, ii. 16 ;
obstinacy of, ii. 20 ; production of,
among the Romans, ii. 88 ; noticed
in the Bible, ii. 186.

Muller, Fritz, reproduction of orchids,
ii. 114-116 ; development of Crustacea,
ii. 363 ; direct action of pollen, i.
431 ; self-sterile bignonia, ii. 117.

MiJLLER, H., on the face and teeth in
dogs, i. 36, 76, ii. 337.

MuLLER, J., tendency to variation, ii.
239 ; atrophy of the optic nerve
consequent on destruction of the
eye, ii. 287 ; on gemmation and
flssion, ii. 351 ; identity of ovules
and buds, ii. 354 ; special affinities
of the tissues, ii. 375.

MiJLLER, Max, antiquity of agriculture,
ii. 230.

Multiplicity of origin of pigeons,
hypotheses of, discussed, i. 197-203.

Muniz, F., on Niata cattle, i. 94.

Munro, R., on the fertilisation of
orchids, ii. 114; reproduction of
Passijiora alita, ii, 119; self-sterile
Passiflora, ibid.

" MuRASSA " pigeon, i. 151.

Murie, Dr., size of hybrids, ii. 112.

Murphy, J. J., the structure of the
eye not producible by selection, ii.
207.

Mus alexandrinus, ii. 64, 65.

Musa sapientium, chinensis and caven-
dishii, i. 401.

Muscari comosum, ii. 169, 306.

Muscles, effects of use on, ii. 287.

Musk duck, feral hybrid of, with the
common duck, i. 200.

Mutilations, inheritance or non-in-
heritance of, ii. 466, 392.

Myatt, on a five-leaved variety of the
strawberry, i. 375.

Myopia, hereditary, i. 453.

Myriapoda, regeneration of lost parts
in, ii. 284, 358.

Nails, growing on stumps of fingers,

ii. 386.
Nais, scission of, ii. 351.
Namaquas, cattle of the, i. 91, ii. 192.
Narcissus, double, becoming single ia

poor soil, ii. 151.

470

NARVAEZ.

INDEX.

KE\VPO..T.

Narvaez, on the cultivation of native |
plants in Florida, i. 329.

Nasua, sterility of, in captivity, ii.
134.

" Natas," or Niatas, a South American
breed of cattle, i. 92-9-1-.

Nathusius, H. von, on striped horses, i.
62 ; on the pigs of the Swiss lake-
dwellings, i. 71; on the races of
pigs, i. 68-72 ; convergence of cha-
racter in highly-bred pigs, i. 76, ii.
227 ; causes of changes in the form
of the pig's skull, i. 75, 76 ; changes
in breeds of pigs by crossing, i. 82 ;

chansre of form in the

P'g, »•

269

effects of disuse of parts in the pig,
ii. 289 ; period of gestation in the
pig, i. 77 ; appendages to the jaw
in pigs, i. 79 ; on Sus pliciceps, i. 72 ;
period of gestation in sheep, i. 101 ;
on Niata cattle, i. 93 ; on short-
horn cattle, ii. 96 ; on interbreeding,
ii. 95 ; in the sheep, ii. 98 ; in pigs,
ii. 101 ; unconscious selection in cattle
and pigs, ii. 198; variability of highly-
selected races, ii. 225.

Nato, p., on the Bizzarria oi'ange, i.
417.

Natural selection, its general princi-
ples, i. 2-14.

Nature, sense in which the term is
employed, i. 6.

N AUDIN, supposed rules of transmission
in crossing plants, ii, 43 ; on the
nature of hybrids, ii. 23, 24; essences
of the species in hybrids, ii. 382,
395 ; reversion of hybrids, ii. 9, 23,
24 ; reversion in flowers by stripes
and blotches, ii. 11; hybrids of Lin-
aria vulgaris and purpurea, ii. 72 ;
pelorism in Linaria, ii. 32, 38 ;
crossing of peloric Linaria with the
normal form, ii. 46 ; variability in
Datura, ii. 254; hybrids of D'dura
Icevis and stramonium, i. 425 ; pre-
potency of transmission of Datura
atrainoniuin when crossed, ii. 43 ; on
the polien of Minhilis and of hybrids,
i. 415 ; fertilisation of 3Iirabiiii<i, ii.
356 ; cultivated Cucurbitaceae, i. 380,
384, ii. 86 ; rudimentary tendrils in
gourds, ii. 306 ; dwarf Cucurbitce, ii.
324 ; relation between the size and
cumber of the fruit in Cucurbita

pepo, ii. 336 ; analogous variation in
CucurbitcB, ii. 341 ; acclimatisation
of Cucurbitacese, ii. 304 ; production
of fruit by sterile hybrid Cucurbi-
taceaj, ii. 156 ; on the melon, i. 383,
ii. 86, 264 ; incapacity of the cucum-
ber to cross with other species, i. 382.

Nectarine, i. 357-365 ; derived from
the peach, i. 357, 360-364 ; hybrids
of, i. 360 ; persistency of characters
in seedling, ibid.; origin of, i. 361,
produced on peach-trees, i, 361, 362 ;
producing peaches, i. 361 ; variation
in, i. 363, 364 ; bud-variation in, i.
398 ; glands in the leaves of the, ii,
217 ; analogous variation in, ii. 341,

Nectary, variations of, in pansies, i.
393.

Nees, on changes in the odour of plants,
ii. 264.

" Negro " cat, i. 48.

Negroes, polydaf^tylism in, i. 548 ;
selection of cattle practised bv, ii.
191.

Neolithic period, domestication of
Bos longifroiis and primigenius in
the, i. 84 ; cattle of the, distinct
from the original species, i. 90 ; do-
mestic goat in the, i. 105 ; cereals of
the, i, 334.

Nerve, optic, atrophy of the, ii. 287.

Neubert, potato-grafting, i, 422.

Neumeister, on the Dutch and German
pouter pigeons, i. 145 ; on the Jaco-
bin pigeon, i. 162 ; duplication of
the middle flight feather in pigeons,
i. 167 ; on a peculiarly coloured
breed of pigeons, " Staarhalsige
Taube," i. 169; fertility of hybrid
pigeons, i, 201 ; mongrels of the
trumpeter pigeon, ii. 42 ; period of
perfect plumage m pigeons, ii. 53 ;
advantage of crossing pigeons, ii. 106.

Neuralgia, hereditary, ii. 55.

New Zealand, feral cats of, i. 49 ;
cultivated plants of, i. 328.

Newfoundland dog, modification of,
in England, i. 44.

Newman, E., sterility of Sphingida*
under certain conditions, ii. 141.

Newport, G., non-copulation of Va'
ness(£ in confinement, ii. 141 ; fer-
tilisation of the ovule in batrachia,
ii. 356.

NEWT.

INDEX.

ORGANISATION.

471

Newt, polydactylism in the, i. 548.

Newton, A., absence of sexual distinc-
tions in the Columbidae, i. 171;
production of a " black-shouldered "
peahen among the ordinary kind, i.
306 ; on hybrid ducks, ii. 140.

Ngami, Lake, cattle of, i. 91.

" NiATA " cattle, i. 92-94 ; resemblance
of, to Sivatheriwn, i. 93 ; prepotency
of transmission of character by, ii.
41.

"Nicard" rabbit, i. 111.

Nicholson, Dr., on the cats of Antigua,
i. 48 ; on the sheep of Antigua, i.
102.

Nicotianaj crossing of varieties and
species of, ii. 87 ; prepotency of
transmission of characters in species
of, ii. 43 ; contabescence of female
organs in, ii. 150.

Kicotima glutinosa, ii, 87.

NiEBUHR, on the heredity of mental
characteristics in some Roman fami-
lies, ii. 40.

Night-blindness, non-reversion to, ii.
10.

NiLSSON, Prof., on the barking of a
young wolf, i. 28 ; parentage of
European breeds of cattle, i. 84, 85 ;
on Bos frontosus in Scania, i. 85.

NiND, Mr., on the dingo, i. 41.

*'Nisus formativus," ii. 283, 284,
348.

NiTZSCH, on the absence of the oil-
gland m certain Columbse, i. 155.

Non-inheritance, causes of, i. 470-
472.

" Konnain" pigeon, i. 161.

NORDMANN, dogs of Awhasie, i. 25.

Normandy, pigs of, with appendages
under the jaw, i. 78.

Norway, striped ponies of, i. 61.

NOTT and Gliddon, on the origin of the
dog, i. 16; mastiff represented on an
Assyrian tomb, i. 17 ; on Egyptian
dogs, i. 18 ; on the Hare Indian dog,
i. 23.

Notijliii, ii. 116.

Nourishment, excess of, a cause of
variability, ii. 244.

Number, importance of, in selection,

ii. 221.
Humid I ptHorhyncha, the original of
the Guinea-fowl, i. 310.

Nun pigeon, i. 163 ; known to Aldro-

vandi, i. 217.
Nutmeg-tree, ii. 223.

Oak, weeping, i. 385, 461; ii. 228;

pyramidal, i. 385 ; Hessian, ibid. ;

late-leaved, i. 386 ; valueless as

timber at the Cape of Good Hope,

ii. 264; changes in, dependent on

age, i. 413 ; galls of the, ii. 272.
Oats, wild, i. 330 ; in the Swiss lake-
dwellings, i. 337.
Oberlin, change of soil beneficial to

the potato, ii. 128.
Odart, Count, varieties of the vine, i.

353, ii, 267 ; bud-variation in the

vine, i. 400.
(Ecidiuin^ ii. 274.
(Enothera biennis, bud-variation in, i.

407.
Ogle, Dr. J. W., inherited deficient

phalanges, i. 458 ; resemblance of

twins, ii. 239, 240.
Oil-gland, absence of, in fantail

pigeons, i. 155, 168.
Oldfield, Mr., estimation of European

dogs among the natives of Australia,

ii. 199.
Oleander, stock affected by grafting

in the, i. 418.
Ollier, Dr., insertion of the periosteum

of a dog beneath the skin of a rabbit,

u. obo.
Oncidium, reproduction of, ii. 114-116,

147.
Onions, crossing of, ii. 68 ; white,

liable to the attacks of fungi and

disease, ii. 213, 330.
Ophrys opifenx, self-fertilisation of, ii.

69 ; formation of pollen by a petal

in, ii. 387.
Opuniia leucotrichi, ii. 267.
Orange, i. 355-356 ; crossing of, ii.

68 ; with the lemon, i. 430, ii. 360 ;

naturalisation of, ^n Italy, ii. 298 ;

variation of, in North Italy, ii. 243 ;

peculiar variety of, ii. 325 ; bizzarria,

i. 417; trifacial, i. 418.
Orchids, reproduction of, i. 434, 435 ;

ii. 114-116.
Orford, Lord, crossing greyhounds with

the bulldog, i. 43.
Organisms, origin ol, i. 13.
Organisation, advancement in, i, S.

472

ORGANS.

INDEX.

PAMPAS.

Organs, rudimentary and aborted, ii.
306-309; multiplication of abnormal,
ii. 385.

Oriole, assumptions of hen-plnmage
by a male in confinement, ii. 141.

Orkney Islands, pigs of, i. 74 ; pigeons
of, i. 193.

Orthoptera, regeneration of hind legs
in the, ii. 284.

Orthosis munda, ii. 141.

Orton, R., on the effects of cross-
breeding on the female, i. 436 ; on
the Manx cat, ii. 41 ; on mongrels
from the silk-fowl, ii. 42 ; infertility
of geese in Quito, ii. 145.

Osborne, Dr., inherited mottling of
the iris, i. 454.

OsPREY, preying on black fowls, ii,
215.

Osten-Sacken, Baron, on American
oak-galls, ii. 272.

OSTEOLOGICAL characters of pigs, i. 69,
70, 74, 77 ; of rabbits, i. 120-134; of
pigeons, i. 171-177 ; of ducks, i. 296-
298.

Ostrich, diminished fertility of the, in
captivity, ii. 140.

Ostvaks, selection of dogs by the, ii.
191.

Otter, ii. 134.

"Otter" sheep of Massachusetts, i.
104.

OuDE, feral humped cattle in, i. 83.

OuisriTi, breed in Europe, ii. 135.

Ovary, variation of, in Cticurbita mos-
chata, i. 382 ; development of, inde-
pendently of pollen, i. 433.

Ovis tnontana, i. 103.

Ovules and buds, identity of nature of,
ii. 353.

OwEDT, Capt., on stiff-haired cats at
Mombas, i. 48.

Owen, Prof. R.,palaeontological evidence
as to the origin of dogs, i. 15; on
the skull of the " Niata" cattle, i.
93 ; on fossil remains of rabbits, i.
108; on the significance of the brain,
i. 130 ; on metagenesis, ii. 362 ;
theory of reproduction and partheno-
genesis, ii. 370.

Owl, eagle, breeding in captivity, ii.
137.

Owl pigeon, i. 156; African, figured i.
157 ;^ known in 1735, i. 218.

Oxalis, trimorphic species of, ii. 394.

Oxalis rosea, ii. 113.

OxLEY, Mr., on the nutmeg-tree, ii,

223.
Oysters, differences in the shells of, ii.

270.

Paca, sterility of the, in confinement,
ii. 135.

Pacific Islands, pigs of the, i. 73.

Padua, earliest known flower-garden
at, ii. 202.

Paduan fowl of Aldrovandi, i. 259.

Pceonia moutin, ii. 189.

PiEONY-TREE, ancient cultivation of, in
China, ii. 189.

Paget, on the Hungarian sheep-dog, i.
24.

Paget, Sir J., inheritance of cancer, i.
451 ; hereditary elongation of hairs
in the eyebrow, i. 452 ; re-growth of
extra digits, i. 459 ; circumcision, i.
467 ; period of inheritance of cancer,
ii. 56 ; on Hydra, ii. 283 ; on the
healing of wounds, ii. 284 ; on the re-
paration of bones, Vjid. ; growth of hair
near inflamed surfaces or fractures,
ii. 285; on false membranes, ibid.;
compensatory development of the
kidney, ii. 290 ; bronzed skin in disease
of supra-renal capsules, ii. 325 ; unity
of growth and gemmation, ii. 352 ;
independence of the elements of the
body, ii. 365 ; affinity of the tissues
for special organic substances, ii. 374.

Pallas, on the influence of domestica-
tion upon the sterility of intercrossed
species, i. 32, 86, 202, ii. 88 ; hypo-
thesis that variability is wholly due
to crossing, i. 197, 398, ii. 237, 252 ;
on the origin of the dog, i. 16; varia-
tion in dogs, i. 34 ; crossing of dog
and jackal, i. 25 ; origin of domestic
cats, i. 46 ; origin of Angora cat, i.
47 ; on wild horses, i. 55, 63 ; on
Persian sheep, i. 98 ; on Siberian fat-
tailed sheep, ii. 269 ; on Chinese
sheep, ii. 306 ; on Crimean varieties
of the vine, i. 353 ; on a grape with
rudimentary seeds, li. 306 ; on feral
musk-ducks, ii. 20 ; sterility of Al-
pine plants in gardens, ii. 147 ; selec-
tion of white-tailed yaks, ii. 190.

Pampas, feral cattle on the, i. 89.

PANDANUS.

INDEX.

PEAS.

473

Pandanus, ii. 2+3.

Pangenesis, hypothesis of, ii. 349-
399.

Panicum, seeds of, used as food, i 326 ;
found in the Swiss lake-dwellings, i.
335.

Paksy, i. 391-393.

Pappus, abortion of the, in Curthamus,
ii. 307.

Paradoiunis, sterility of species of, in
captivity, ii. 134.

Paraguay, cats of, i. 48 ; cattle of, i.
92 ; horses of, ii. 80 ; dogs of, i'>id. ;
black-skinned domestic fowl of, i.
243.

Parallel variation, ii. 341-345.

Paramos, woolly pigs of, i. 81.

Parasites, liability to attacks of, de-
pendent on colour, ii. 213.

Pariah dog, with crooked legs, i. 17 ;
resembling the Indian wolf, i. 25.

Pariset, inheritance of handwriting, ii.
6.

Paritium - tricuspis, bud-variation, i.
402.

Parker, W. K., number of vertebras in
fowls, i. 280.

Parkinson, Mr., varieties of the hya-
cinth, i. 394.

Parkyns, Mansfield, on Columha
guinea, i. 192.

Parmentier, differences in the nidifi-
cation of pigeons, i. 188; on white
pigeons, ii. 215.

Parrots, general sterility of, in con-
finement, ii. 138; alteration of plu-
mage of, ii, 269.

Parsnip, reversion in, ii. 34; influence
of selection on, ii. 185 ; experiments
on, ii. 267 ; wild, enlargement of
roots of, by cultivation, i. 344.

Parthenogenesis, ii. 352, 356.

Partridge, sterility of, in captivity,
ii. 139.

Parturition, difficult, hereditary, i.
452.

Parus major, ii. 216.

Passiflora, self-impotence in species of,
ii. 118, 119; coutabescence of female
organs in, ii. 150.

Passiflora akda, fertility of, when
grafted, ii. 172.

Pastrana, Julia, peculiarities in the
hair and teeth of, ii. 321.

Pasture and climate, adaptation of
br<^eds of sheep to, i. 99, 100.

Patagonia, crania of pigs from, i. 81.

Patagonian rabbit, i. 110.

Paterson, R., on the Arrindy silk-
moth, ii. 296.

Paul, W., on the hyacinth, i. 394, 395 ;
varieties of pelargoniums, i. 403;
weakness of transmission in holly-
hocks, ii. 42 ; improvement of pelar-
goniums, ii. 201.

Pavo crislatus and muticus, hybrids of, i,
306.

Pavo nigripennis, i. 305-307.

" Pavodotten-Taube," i. 1 48.

Peach, i. 357-365 ; derived from the
almond, i. 357 ; stones of, figured,
358 ; contrasted with almonds, i.
359 ; double-flowering, i. 358, 359,
364 ; hybrids of, i. 360 ; persistency
of races of, ibid. ; trees producing
nectarines, ibid.; variation in, i. 363,
364, ii. 243 ; bud-variation in, i.
398; pendulous, i. 461; variation
by selection in, ii. 203 ; peculiar
disease of the, ii. 213 ; glands on the
leaves of the, ii. 217 ; antiquity of
the, ii. 299 ; increased hardiness of
the, ibid. ; varieties of, adapted for
forcing, ii. 301 ; yellow-fleshed,
liable to certain diseases, ii. 330.

Pi:ach-al3I0ND, i. 359.

Peafowl, origin of, i. 305 ; japanned
or black-shouldered, i. 305-307 ;
feral, in Jamaica, i. 199 ; compara-
tive fertility of, in wild and tame
states, ii. 91, 256 ; white, ii. 326.

Pears, i. 372 ; bud-variation in, i. 401 ;
reversion in seedling, ii. 4 ; inferiority
of, in Pliny's time, ii. 200; winter
nelis, attacked by aphides, ii. 217 ;
soft-barked varieties of, attacked by
wood-boring beetles, ii. 217 ; origina-
tion of good varieties of, in woods,
ii. 242 ; Forelle, resistance of, to
frost, ii. 297.

Peas, i. 345-349; origin of. i. 345
varieties of, i. 345-349 ; found in Swiss
lake-dwellings, i. 335, 337, 345-349 ;
fruit and seeds figured, i. 347 ;
persistency of varieties, i. 348 ; inter-
crossing of varieties, i. 349, 428, ii.
110 ; effect of crossing on the female
organs in, i. 429 ; double-flowered, ii.

i74

PECCARY.

INDEX.

PHLOX,

152; maturity of, accelerated by
selection, ii. 185 ; varieties of, pro-
duced by selection, ii. 203 ; thiu-
shelled, liable to the attacks of birds,
ii. 216; reversion of, by the terminal
seed in the pod, ii. 339.

Peccary, breeding of the, in captivity,
ii. 133.

Pedigrees of horses, cattle, greyhounds,
game-cocks, and pigs, i. 447.

Pegu, cats of, i. 49 ; horses of, i. 56.

Pelargoniums, multiple origin of, i.
388 ; zones of, i. 390 ; bud-variation
in, i. 402 ; variegation in, accom-
panied by dwarfing, i. 409; pelorism
in, ii. 150, 337 ; by reversion, ii. 33 ;
advantage of change of soil to, ii. 1 29 ;
improvement of, by selection, ii. 201 ;
scorching of, ii. 214; numbers of,
raised from seed, ii. 221 ; effects of
conditions of life on, ii. 263 ; stove-
variety of, ii. 301 ; correlation of
contracted leaves and flowers in, ii.
324, 325.

Pelargonium fulgidum, conditions of
fertility in, ii. 147.

" Pelones," a Columbian breed of cattle,
i. 92, 212.

Peloric flowers, tendency of, to ac-
quire the normal form, ii. 46 ; fer-
tility or sterility of, ii. 150, 151.

Peloric races of Gloxinia speciosa and
Antirrhinum majus, i. 389.

Pelorism, ii. 32-34, 337, 338.

Pelvis, characters of, in rabbits, i. 128 ;
in pigeons, i. 176 ; in fowls, i. 281 ;
in ducks, i. 298.

Pembroke cattle, i. 84.

Pendulous trees, i. 385, ii. 340; un-
certainty of transmission of, i. 461,
462.

Penguin ducks, i, 294, 296 ; hybrid of
the, with the Egyptian goose, i.
296.

Pennant, production of wolf-like curs
at Fochabers, i. 39 ; on the Duke of
Qiieensberry's wild cattle, i. 88.

Pennisetum, seeds of, used as food in
the Punjab, i. 326.

Pennisetum distichum, seeds of, used as
food in Central Africa, i. 326.

Percival, Mr., on inheritance in horses,
i. 455; on horn-like processes in
horses, i. 52.

Perdix rubra, occasional fertility of, in

captivity, ii. 139.
Period of action of causes of variability,

ii. 257.
Periosteum of a dog, producing bone

in a rabbit, ii. 365.
Periwinkle, sterility of, in England,

ii. 158.
Persia, estimation of pigeons in, i. 215

carrier pigeon of, i. 148 ; tumbler

pigeon of, i, 156; cats of, i. 47-49

sheep of, i. 102.
Persistence of colour in horses

i. 53 ; of generic peculiarities, i

114.
Peru, antiquity of maize in, i. 338

peculiar potato from, i. 350 ; selection

of wild animals practised by the

Incas of, ii. 191, 192.
" Perucken-Taube," i. 161.
Petals, rudimentary, in cultivated

plants, ii. 307 ; producing pollen, ii.

387.
Petunias, multiple origin of, i.

388.
Peyritsch, Dr., vegetable teratology,

ii. 32.
" Pfauen-Taube," i. 153.
Phalcenopsis, pelorism in, ii. 338.
Phalanges, deficiency of, ii. 49.
Fhaps ch'dcoptera, ii. 342.
Phaseolus multiflorus, ii. 300, 314.
Ph iseolus vulgaris, i. 350, ii. 300.
Phasianus pictus, i. 289.
Phasianus amherstix, i. 289.
Pheasant, assumption of male plumage

by the hen, ii. 26 ; wildness of hybrids

of, with the common fowl, ii. 19 ;

pre|)otency of the, over the fowl, ii.

43 ; diminished fecundity of the, in

captivity, ii. 139.
Pheasants, golden and Lady Amherst's,

i 289.
Pheasant-fowls, i. 256.
Philipeaux, regeneration of limbs in

the salamander, ii. 359.
Philippar, on the varieties of wheat, i.

332.
Philippine Islands, named breeds o{

game fowl in the, i. 243.
Phillips, Mr., on bud-variation in the

potato, i. 411.
Phlox, bud-variation by suckers in, L

410.

PHTHISIS,

INDEX.

PIGS.

475

Phthisis, aflfection of the fingers in, ii.
326.

Phylloxera, i. 354,

Pickering, Dr., on the grunting voice
of humped cattle, L 83 ; occurrence
of the head of a fowl in an ancient
Egyptian procession, i. 258 ; seeding
of ordinarily seedless fruits, ii. 152 ;
extinction of ancient Egyptian breeds
of sheep and oxen, ii. 421 ; on an
ancient Peruvian gourd, ii. 425.

PiCOTEES, eftect of conditions of life on,
ii. 262,

PiCTET, A., oriental names of the pigeon,
i. 215.

PiCTET, Prof., origin of the dog, i. 15;
on fossil oxen, i. 85.

Piebalds, probably due to reversion, ii.
11.

Pie iREMENT, M., on the ribs of horses,
i. 52.

PiGEAUX, hybrids of the hare and
rabbit, ii. 135.

PiGEOX a cravate, i. 156.

PiGEOX bagadais, i. 149, 150.

Pigeon coquille, i. 163.

Pigeon cygne, i. 150.

Pigeon heurte^ i. 163,

Pigeon pattu plongeur, i. 164,

Pigeon polonais, i. 151.

Pigeon remain, L 149. 150.

Pigeon tambour, i. 162,

Pigeon turc, i. 146.

Pigeons, originof, i. 137, 140, 189-214 ;
classified table of breeds of, L 142 ;
pouter, i. 143-145; carrier, i. 146-
149; runt, i, 149-151; barbs, i.
151-153 ; faatail, i. 153-155 ; turbit
and owl, i. 156 ; tumbler, i. 156-161 ;
Indian frill-back, u 161 ; Jacobin,
ibid.; trumpeter, i. 162; other breeds
of, i. 163-165; difterences of, equal
to generic, i. 166; individual varia-
tions of, i. 167-169 ; variability of
peculiarities characteristic of breeds
in, i. 169; sexual variability in, i.
170, 171; osteology of, i. 171-177;
correlation of growth in i. 177-180,
ii. 313 ; young of some varieties
naked when hatched, i. 179, ii. 326 ;
etiects of disuse in, i. 180-187 ; set*
tling and roosting in trees, i. 190 ;
floating in the !Nile to drink, ibid.;
dovecot, i- 194, 195; arguments for

unity of origin of, i. 197-214; feral,
in various places, i. 199, ii. 7 ; unity
of coloration in, i. 204-206 ; reversion
of mongrel, to coloration of C. livia,
I. 207-214; history of the cultivation
of, i. 215-217 ; history of the princi-
pal races of, i. 217-222 ; mode of
production of i*aces of, i. 222-235 ;
reversion in, ii. 22 ; by age, ii. 14 ;
produced by crossing in, ii. 14, 22 ;
prepotency of transmission of cha-
racters in breeds of, ii. 41, 42; sexual
diflferences in some varieties of, ii. 50 ;
period of perfect plumage in, ii. 53 ;
ellect of segregation on, ii. 63 ; pre-
ferent pairing of, within the same
breed, ii. 81 ; fertility of, increased by
domestication, ii. 90, 138; effects of
inter-breeding and necessity of cross-
ing, ii. 106 ; indifference of, to change
of climate, ii. 144 ; selection of, ii.
79, 183, 188 ; among the Romans,
ii. 187 ; unconscious selection of, ii.
196, 198 ; facility of selection of, ii.
220; white, liable to the attacks of
hawks, ii. 215 ; effects of disus<3
of parts in, ii. 288 ; fed upon meat,
ii. 294 ; effect of first male upon the
subseqv:ent progeny of the female,
i. 437 ; homology of the leg and wing
feathers in, ii. 315 ; union of two
outer toes in feather-legged, ibid. ;
correlation of beak, limbs, tongue,
and nostrils, ii. 316; analogous
variation in, ii. 341, 342 ; permanence
of breeds of, ii. 425.
Pigs, of Swiss lake-dwellings, i. 71 ;
types of, derived from Sns scrofa and
Sus indicus, i. 68-70 ; Japanese (^Sus
pliciceps, Gray), figured, i. 72 ; of
Pacific Islands, i. 73, ii. 64 ; modifica-
tions of skull in, i. 72-75 ; length of
intestines in, i. 77, ii. 293 ; period of
gestation of, i. 77 ; number of verte-
bras and ribs in, ibid. ; anomalous
forms, i. 78, 79 ; development of
tusks and bristles in, i. 79 ; striped
young of, i. 80 ; reversion of feral,
to wild type, i. 80, 81, ii. 7, 22 ;
production and changes of breeds
of, by inter-crossing, i. 82 ; etl'ects
produced by the first male upon
the subsequent progeny of the
female, i. 436 ; j)edigrees of, i. 447 ;

i76

riMENTA.

INDEX.

POIS.

polydactylism in, i. 459 ; cross-re-
version in, ii. 8 ; hybrid, wildness
of, ii, 19; disappearance of tusks
in male under domestication, ii,
50 ; solid-hoofed, ii. 424 ; crosses of,
ii. 70, 73 ; mutual fertility of all
varieties of, ii. 89 ; increased fertility
by domestication, ii. 90 ; ill effects of
close interbreeding in, ii. 100, 101 ;
influence of selection on, ii. 182 ;
prejudice against certain colours in,
ii. 194, 214, 330 ; unconscious selec-
tion of, ii. 199; black Virginian, ii.
212, 330 ; similarity of the best
breeds of, ii. 227 ; change of form in,
ii. 269 ; effects of disuse of parts in,
ii. 289 ; ears of, ii. 291 ; correlations
in, ii. 320 ; white buck-wheat in-
jurious to, ii. 331; tail of, grafted
upon the back, ii. 365 ; extinction of
the older races of, ii. 421.

PiMENTA, ii, 68.

Pimp£;rnel, ii. 173.

Pine-apple, sterility and variability
of the, ii, 256.

Pink, Chinese, 314. •

Pinks, bud-variation in, i, 406 ; im-
provement of, ii. 201.

Pinus puinilio, mnghus, and nana, varie-
ties of F. sylvestris, i. 387.

Pinus sylvestris, i. 386, ii. 300 ;
hybrids of, with P. nijricans, ii.
111.

PiORRY, on hereditary disease, i. 451,
ii, 54.

Pisiacia lentiscus, ii. 264.

Pistacia vera, i. 431.

Pistils, rudimentary, in cultivated
plants, ii, 307.

PiSTOR, sterility of some mongrel
pigeons, i. 202 ; fertility of pigeons,
ii, 91.

Pisum arvense and sativum, i. 345.

Pityriasis versicolor, inheritance of,
ii, 55.

Planchon, G., on a fossil vine, i, 352 ;
sterility of Jussiuea grandijiora in
France, ii. 154,

Plane-tree, variety of the, i, 386.

Plantigrade carnivora, general ste-
rility of the, in captivity, ii. 134.

Plants, progress of cultivation of, i.
322, 329; cultivated, their geogra-
phical derivation, i, 328 ; crossing

of, ii. 76, 107 ; comparative fer-
tility of wild and cultivated, ii. 91;
self-impotent, ii. 112-122; dimor-
phic and trimorphic, i'nd. ; sterility
of, from changed conditions, ii. 146-
149 ; from contabescence of anthers,
ii. 149, 150; from monstrosities, ii.
150, 151 ; from doubling of the
flowers, ii. 151, 152 ; from seedless
fruit, ii. 152 ; from excessive de-
velopment of vegetative organs, ii.
152-155 ; influence of selection on,
ii. 183-185; variation by selection,
in useful parts of, ii. 202-204;
variability of, ii. 223 ; variability of,
induced by crossing, li. 252 ; direct
action of change of climate on, ii.
266 ; change of period of vegetation
in, ii. 295 ; varieties of, suitable to
different climates, ii. 296 ; correlated
variability of, ii. 323-325 ; antiquity
of races of, ii. 425.

Plasticity, inheritance of, ii. 227.

Plateau, F., on the vision of amphi
bious animals, ii. 208.

Platessa flesus, ii. 28.

Plato, notice of selection in breeding
dogs by, ii. 186.

Plica polonica, ii. 265.

Pliny, on the crossing of shepherd
dogs with the wolf, i. 24 ; on Pyr-
rhus' breed of cattle, ii. 186 ; on the
estimation of pigeons among the
Romans, i. 215; pears described by,
ii. 200.

Plum, i. 366-368 ; stones figured, i.
366 ; varieties of the, i. 367, 368 ; ii.
204 ; bud-variation in the, i. 399 ;
peculiar disease of the, ii. 213 ;
flower-buds of, destroyed by bull-
finches, ii, 217 ; purple-fruited, liable
to certain diseases, ii, 330.

Plumage, inherited peculiarities of, in
pigeons, i. 169, 170; sexual pecu-
liarities of, in fowls, i, 263-268.

Plurality of races, Pouchet's views
on, i. 2.

Poa, seeds of, used as food, i. 326 ;
species of, propagated by bulblets, ii.
154.

PoDOLiAN cattle, i. 84.

Pointers, modification of, i, 44*
crossed with the foxhound, ii. 73.

Pois sans parchemin, ii. 216.

FOITEAU.

INDEX.

PROCYON.

477

PoiTEAU, origin of C>/tisus adamt, i.
416; origin of cultivated varieties of
fruit-trees, ii. 247.

Polish fowl, i. 239, 262, 266, 269, 270,
275 ; skull figured, i. 275 ; section of
skull figured, i. 277 ; development of
protuberance of skull, i. 262 ; fur-
culum figured, i. 282.

Polish, or Himalayan rabbit, i. 112.

Pollen, ii. 356, 357 ; action of, ii.
86 ; injurious action of, in some
orchids, ii. 115,116; resistance of,
to injurious treatment, ii. 148 ; pre-
potency of, ii. 171.

Pollock, Sir F., transmission of varie-
gated leaves in Ballota nigra, i. 409 ; on
local tendency to variegation, ii. 263.

Polyanthus, i. 464.

POLYDACTYLISM, inheritance of, i. 457-
459 ; significance of, i. 460.

Ponies, most frequent on islands and
mountains, i. 54 ; Javanese, i. 56.

Poole, Col., on striped Indian horses, i.
61, 62; on the young of Asinus hi'
dicits, ii. 17.

Poplar, Lombardy, i. 385.

PoPPiG, on Cuban wild dogs, i. 28.

Poppy, found in the Swiss lake-dwell-
ings, i. 335, 337 ; with the stamens
converted into pistils, i. 389 ; differ-
ences of the, in different parts of
India, ii. 149 ; monstrous, fertility of, ii.
150 ; black-seeded, antiquity of, ii. 425.

Porcupine, breeding of, in captivity,
ii. 135.

Porcupine family, i. 448, ii. 53.

Porphyria, breeding of a species of, in
captivity, ii. 140.

Portal, on a peculiar hereditary affec-
tion of the eye, i. 454.

Porto Santo, feral rabbits of, i. 117.

Portulaca oleracea, ii. 275.

Potamochcerus penicillatus, ii. 133.

Potato, i. 350, 351 ; bud-variation by
tubers in the, i. 410, 411; graft-
hybrid of, by union of half-tubers, i.
420 ; individual self-impotence in the,
ii. 118; sterility of, ii. 153; advan-
tage of change of soil to the, ii. 128.

Potato, sweet, sterility of the, in
China, ii. 153; varieties of the,
suited to different climates, ii. 299.

Pouchet, M., his views on plurality of
races, i. 2.

Pouter pigeons, i, 143-145 ; furculum
figured, i. 176 ; history of, i. 217.

Powis, Lord, experiments in crossing
humped and English cattle, i. 86, ii.
19.

Poynter, Mr., on a graft-hybrid rose,
i. 419.

Prairie wolf, i. 22.

Precocity of highly-improved breeds,
ii. 313.

Prepotency of pollen, ii. 171.

Prepotency of transmission of charac-
ter, ii. 40, 158; in the Austrian
emperors and some Roman families,
ii. 40 ; in cattle, ii. 40, 41 ; in sheep,
ii. 41 ; in cats, ibid. ; in pigeons, ii. 41,
42 ; in fowls, ii. 42 ; in plants, i6«af. ; in
a variety of the pumpkin, i. 380 ;
in the jackal over the dog, ii. 43; in
the ass over the horse, ibid. ; in the
pheasant over the fowl, ibid. ; in the
penguin duck over the Egyptian
goose, ii. 44; discussion of the phe-
nomena of, ii. 44-47.

Prescott, Mr., on the earliest known
European flower-garden, ii. 202.

Pressure, mechanical, a cause of
modification, ii, 336, 337.

Prevost and Dumas, on the employ-
ment of several spermatozoids to fer-
tilise one ovule, ii. 356.

Preyer, Prof., on the effect of circum-
cision, i. 467.

Price, Mr., variations in the structure
of the feet in horses, i. 52.

Prichard, Dr., on polydactylism in the
negro, i. 458 ; on the Lambert family,
ii. 53; on an albino negro, ii. 214;
on Plica polonica, ii. 266.

Primrose, i. 464; double, rendered
single by transplantation, ii. 151.

Pi'imula, inter-crossing of species of, i.
356 ; contabescence in, ii. 150 ; ' hose
in hose,' i. 389 ; with coloured
calyces, sterility of, ii. 149.

Primula sinensis, variations, i. 394; ii.
324; reciprocally dimorphic, ii. 113.

Primula veris, i. 464, ii. 87.

Primula vulgaris, i. 464, ii. 87.

Prince, Mr., on the inter-crossing of
strawberries, i. 374.

Pringsheim, on conjugation, ii. 352.

Proojon, sterility of, in captivity, ii.
134.

i78

PROLIFICNESS.

INDEX.

RAFFLES.

Prolificness, increased by domestica-
tion, ii. 158.

Protozoa, reproduction of the, ii. 371.

Prunus armeniaca, i. 365, 366.

Prunus avium, i. 368.

Prunus cerasus, i, 3c8, 399.

Prunus domestica, i. 366.

Prunus insititia, i. 366—338.

Prunus spinosa, i. 366.

Prussia, wild horses in, i. 63.

Psittacus erithacus, ii. 138.

Psittacus macoa, ii. 138.

Psophia, general sterility of, in cap-
tivity, ii. 140.

Ptarmigan fowls, i. 240.

Pulex penetrans, ii. 265.

Pumpkins, i. 380.

PUNO ponies of the Cordillera, i. 54.

PUSEY, Mr., value of cross-bred sheep, ii.
99 ; preference of hares and rabbits
for common rye, ii. 218.

PuTSCHE and Vertuch, varieties of the
potato, i. 350.

Puvis, effects of foreign pollen on
apples, i. 432 ; supposed non-varia-
bility of monotypic genera, ii. 253.

Pyrrhula vulgaris, ii. 217; assumption
of the hen-plumage by the male, in
conHnement, ii. 141.

Pyrrhus, his breed of cattle, ii. 186.

Pyrus, fastigate Chinese species of, ii.
266.

Pyrus acerba, i. 369.

Pyrus aucuparia, ii. 216.

Pyrus communis, i. 372, 401.

Pyrus malus, i. 369, 401.

Pyrus paradisiaca, i. 369,

Pyrus proecox, i. 370.

QUAGGA, previous impregnation by, i,
435.

QuATREFAGES, A. DE, on the burrowing
of a bitch to litter, i. 28; selection
in the silkworm, i. 317 ; development
of the wings in the silkmoth, i. 320,
ii. 288 ; on varieties of the mulberry,
i. 354 ; special raising of eggs of the
silk-moth, ii. 181 ; on disease of the
silkworm, ii. 213; on monstrosities
in insects, ii. 257, 385 ; on a change in
the breeding season of the Egyptian
goose, ii. 294 ; fertilisation of the
Teredo, ii. 356 ; tendency to simi-
larity in the best races, li. 227 ; on

his " tourhillon vital," ii. 35 ; on the

independent existence of the sexual

elements, ii. 352.
Que reus cerris, i. 386.
Quercus robur and pedunculata, hybrids

of, ii. 111.
Quince, pears grafted on the, ii. 246.

Rabbits, domestic, their origin, i. 107-
109 ; of Mount Sinai and Algeria, i.
109; breeds of, i. 109-116; Hima-
layan, Chinese, Polish, or Russian, i.
112-115, ii. 75; feral, i. 116-120;
of Jamaica, i. 116; of the H'alklund
Islands, ibid. ; of Porto Santo, i.
117-120, ii. 81, 269; osteologioal
characters of, i. 120-134; discussion
of modifications in, i. 135-140 ; one-
eared, transmission of peculiarity of,
i. 456 ; reversion in feral, ii. 6 ; in
the Himalayan, ii. 15; crossing of
white and coloured Angora, ii, 70 ;
comparative fertility of wild and
tame, ii. 90 ; falsified experiments in
interbreeding of, ii. 100 ; high-bred,
often bad breeders, ibid. ; selection
of, ii. 188 ; white, liable to destruc-
tion, ii. 215; effects of disuse of
parts in, ii. 288; skull of, affected
by drooping ears, ii. 291 ; length of
intestines in, ii. 293 ; correlation of
ears and skull in, ii. 316, 317 ; varia-
tions in skull of, ii. 343 ; periosteum
of a dog producing bone in, ii.
365.

Race-horse, origin of, i. 56.

Races, modification and formation of,
by crossing, ii. 73-77 ; natural and
artificial, ii. 232 ; Pouchet's views on
plurality of, i. 2 ; of pigeons, i. 217-
222.

Radclyffe, W. F., effect of climate
and soil on strawberries, i. 376 ; con-
stitutional differences in roses, i.
391.

Radishes, i. 345 ; crossing of, ii. 68 ;
varieties of, ii. 202.

Radlkofer, retrogressive metamor-
phosis in mosses and algae, ii. 354.

Rafarin, M., bud-variation and rever-
sion, i. 403.

Raffles, Sir Stamford, on the crossing
of Javanese cattle with Bos sondaicus^
ii. 191.

RAM.

INDEX.

REVERSION.

479

Ram, goat-like, from the Cape of Good
Hope, ii. 41.

Ramu, M., on appendages to throat of
goat, i. 106.

Ranchxn, heredity of diseases, i. 451.

Range of gallinaceous birds on the
Himalaya, i. 249.

Ranke, on the effects of use and disuse
of organs, ii. 285.

Ranunculus ficaria, ii. 154.

Ranunculus repens, ii. 152.

Rape, i. 344.

Raphanus caudatus, i. 345.

Raphanus raphanistrum, i. 345.

Raphanus sativus, ii. 335.

Raspberry, yellow-fruiterl, ii. 216.

Rattlesnake, experiments with poison
of the, ii. 279.

Raven, stomach of, affected by vege-
table diet, ii. 292.

Raavson, a., self-impotence in hybrids
of Gladiolus, ii. 121, 122.

Re, Comte, on the assumption of a
yellow colour by all varieties of maize,
i. 339.

Reaumur, effect of confinement upon
the cock, ii. 27 ; fertility of fowls in
most climates, ii. 144.

Reed, Mr., atrophy of the limbs of
rabbits, consequent on the destruc-
tion of their nerves, ii. 287.

Regeneration of amputated parts in
man, i. 459 ; in the human embryo,
ii. 357 ; in the lower vertebrata,
insects, and myriapoda, ii. 358.

Re-growth of amputated joints, ii.
357.

Regnier, early cultivation of the cab-
bage by the Celts, i. 342 ; selection
practised by the Celts, ii. 187.

Reindeer, individuals recognised by
the Laplanders, ii. 238.

Reissek, experiments in crossing Cytisus
pnrpureus and laburnum, i. 416 ; mo-
dification of a Tuesium by CEcidium,
ii. 274.

Relations, characters of, reproduced
in children, ii. 7.

Rengger, occurrence of jaguars with
crooked legs in Paraguay, i. 17 ;
nahed dogs of Paraguay, i. 24, 32, ii.
70, 80 ; feral dogs of La Plata, i. 28 ;
on the aguara, i. 27 ; cats of Para-
guay, i. 48, ii. 63, 133; dogs of Para-

guay, ii. 64; feral pigs of Buenos
Ayres, i. 80 ; on the refusal of wild
animals to breed in captivity, ii. 132 ;
on Dicuti^les labiatus, ii. 133 ; sterility
of plantigrade carnivora in captivity,
ii. 134; on Cavia aperea, ibid.;
sterility of Cebus azarce in captivity,
ii. 136 ; abortions produced by wild
animals in captivity, ii. 142.

Reproduction, sexual and asexual,
contrasted, ii. 351 ; unity of forms
of, ii. 378; antagonism of, to growth,
ii. 379.

Reseda odorata, self-sterility of, ii. 118,
223.

Retinitis, pigmentary, in deaf-mutes,
ii. 322.

Reuteu, Herr, potato-grafting, i.
422.

RevePvSION, ii. 1, 2, 368, 369, 390, 393-
399 ; in pigeons, ii. 2 ; in cattle, ii.
3 ; in sheep, ibid. ; in fowls, ii. 4 ; in
the heartsease, ibid. ; in vegetables,
ibid. ; in feral animals and plants, ii.
5-7 ; to characters derived from a
previous cross in man, dogs, pigeons,
pigs, and fowls, ii. 7-9 ; in hyi.rids,
ii. 9; by bud-propagation in plants,
ii. 10-13; by age in fowls, cattle,
&c., ii. 12, 13 ; partial, from an in*"
jury, ii. 12 ; caused by crossing, ii.
13-25; explained by latent charac-
ters, ii. 25-31 ; producing monstro-
sities, ii. 31 ; producing peloric
flowers, ii. 32-34 ; of feral pigs to
the wild type, i. 81, 82 ; of supposed
feral rabbits to the wild type, i. 108,
116, 118; of pigeons, in coloration,
when crossed, i. 206-213; in fowls,
i. 251-258; in the silkworm, i. 318;
in the pansy, i. 393 ; in a pelargo-
nium, i. 403; in Chrysanthemums,
i. 404; of varieties of the China rose
in St. Domingo, i. 406 ; by buds in
pinks and carnations, i. 407 ; of la-
ciniated varieties of trees to the
normal form, i. 408; in variegated
leaves of plants, i. 409; in tulips, i.
412; of suckers of the seedless bar-
berry to the common form, i. 410 ;
by buds in hybrids of Tropceolum, i.
425 ; in plants, i. 442 ; of crossed
peloric snapdragons, ii. 46 ; analogous
variations due to, ii, 340-B44.

480

RHINOCEROS.

IXDEX.

ROSA.

Rhinoceros, breeding in captivity in
India, ii. 132.

Rhododendron, hybrid, ii. 253.

Rhododendron cilia tum, ii. 267.

Rhododendron dalhousioe, effect of pol-
len of R. nuttallii upon, i. 431.

Ribes grossularia, i. 376-378, 400.

Ribes rubrum, i. 400.

Bibs, number and characters of, in
fowls, i. 280 ; characters of, in ducks,
i. 297, 298.

Rice, imperial, of China, ii. 189 ; In-
dian varieties of, ii. 243 ; variety of,
n)t requiring water, ii. 295.

Richardson, H. D., on jaw-appendages
in Irish pigs, i. 79; management of
pigs in China, i. 71 ; occurrence of
striped young in Westphalian pigs, i.
80 ; on crossing pigs, ii. 73 ; on in-
terbreeding pigs, ii. 102 ; on selection
in pigs, ii. 178.

Richardson, Sir John, observations on
the resemblance between North Ame-
rican dogs and wolves, i. 21, 22; on
the burrowing of wolves, i. 28 ; on
the broad feet of dogs, wolves, and
foxes in North America, i. 42 ; on
North American hoi-ses scraping away
the snow, i. 55.

Ricinus, annual in England, ii. 295,

ElEDEL, Dr., on the " Bagadotte "
pigeon, i. 148 ; on the Jacobin pi-
geon, i. 162; fertility of hybrid
pigeons, i. 201 ; circumcision, i. 467.

Riley, on Phylloxera, i. 354.

Rinderpest, ii. 373.

RiNTOUL, Mr., potato - gi-afting, i.
421.

Risso, on varieties of the orange, 1. 357,
ii. 298, 324.

RrVERS, Lord, on the selection of grey-
hounds, ii. 221.

RrVERS, Mr., persistency of characters
in seedling potatoes, i. 351 ; on the
peach, i. 357, 359 ; persistency of
races in the peach and nectarine, i.
360, 361 ; connection between the
peach and the nectarine, i. 361 ; per-
sistency of character in seedling
apricots, i. 366 ; origin of the plum,
ibid.; seedling varieties of the
plum, i. 367 ; persistency of cha-
racter in seedling plums, i. 368 ;
bud-variation in the plum, i. 399 ;

plum attacked by bullfinches, ii"
217 ; seedling apples with surface-
roots, i. 371 ; variety of the apple
found in a wood, ii. 247 ; on roses,
i. 390, 391 ; bud-variation in roses,
i. 404-406 ; production of Provence
roses from seeds of the moss-rose, i.
405 ; effect produced by grafting on
the stock in jessamine, i. 418 ; in the
ash, ibid.; on grafted hazels, i. 419;
hybridisation of a weeping thorn, i.
461 ; experiments with the seed of
the weeping elm and ash, i. 462 ;
variety of the cherry with curled
petals, ii. 218.

Riviere, reproduction of Oncidium cu'
vendishimum, ii. 114.

Roberts, Mr., on inheritance in the
horse, i. 454.

Robertson, Mr., on glandular-leaved
peaches, i. 364.

ROBiNET, on the silkworm, i. 317-321,
ii. 181.

Robinia, ii. 264.

ROBSON, Mr., deficiencies of half-bred
horses, i. 455.

RoBSON, Mr., on the advantage of
change of soil to plants, ii. 128, 129;
on the growth of the verbena, ii.
263 ; on broccoli, ii. 301.

Rock pigeon, measurements of the, i.
140; figured, i. 141.

Rodents, sterility of, in captivity, ii.
134.

Rodriguezia, ii. 115, 116.

RODWELL, J., poisoning of horses by
mildewed tares, ii. 331.

Rohilcund, feral humped cattle in, i.
83.

ROLLE, F., on the histoiy of the peach,
ii. 299.

ROLLER-piGEONS, Dutch, i. 158.

RoiXESTON, Prof., inherited effects of
injuries, i. 469 ; incisor teeth af-
fected in form in cases of pulmonary
tubercle, ii. 325.

Romanes, on sternum of the fowl, i.
288; rudimentary organs, ii. 309.

Romans, estimation of pigeons by, i.
215; breeds of fowls possessed by, i.
243, 258.

Rooks, pied, ii. 53.

Rosa, cultivated species of, i. 390.

Rosa devoniensis, graft-hybrid produced

ROSA.

INDEX.

SALAMANDER.

481

by, ou the white Banksian rose, i.
419.

Rosa indica and centifolia, fertile hybrids
of, i. 390.

Sosa spiriosissima, history of the culture
of, i. 391.

RosELLiNi, on Egyptian dogs, i. 17.

Roses, i. 390, 391; origin of, i. 388;
bud-variation in, i. 404-406 ; Scotch,
doubled by selection, ii. 185 ; con-
tinuous variation of, ii, 228 ; effect
of seasonal conditions on, ii. 263 ;
noisette, ii. 299 ; galls of, ii. 274.

Ross, Dr., on Pangenesis, ii. 350, 377.

RoUENNAis, rabbit, i. 109.

ROUJOU, polydactylism, and arrested
development, i. 458.

ROULIN, on the dogs of Juan Fernandez,
i. 27 ; on South American cats, i, 48;
striped young pigs, i. 80 ; feral pigs
in South America, i. 81, ii. 7 ; on
Columbian cattle, i. 92, ii. 189, 212 ;
eftects of heat on the hides of cattle
in South America, i. 95 ; fleece of
sheep in the hot valleys of the Cor-
dilleras, i. 102 ; diminished fertility
of these sheep, ii. 145 ; on black-
boned South American fowls, i. 271 ;
variation of the guinea-fowl in tropical
America, i. 310 ; frequency of striped
legs in mules, ii. 16; geese in Bogota,
ii. 145 ; sterility of fowls introduced
into Bolivia, ii. 145.

ROY, M., on a variety of Magnolia gran-
diflora, ii. 299.

ROYLE, Dr., Indian varieties of the mul-
berry, i. 354 ; on Agave vivipara, ii.
153 ; variety of rice not requiring
irrigation, ii. 295 ; sheep from the
Cape in India, ii. 296.

Evhus, pollen of, ii. 256.

RUDIMENTAKY organs, i. 12, ii, 306-310.

RUFZ DE Lavison, extinction of breeds
of dogs in France, ii. 421.

Ruminants, general fertility of, in cap-
tivity, ii. 133.

Rumpless fowls, i. 241.

Runts, i. 149-151 ; history of, i. 220 ;
lower jaws and skull figured, i. 173.

Russell, Lord A., spiegelcarpe, ii. 222.

Russian or Himalayan rabbit, i. 112.

RiJTiMEYER, Prof, dogs of the Neolithic
period, i. 19 ; horses of Swiss lake-
dwellings, i. 51 ; diversity of early

domesticated horses, i. 53 ; pigs of the
Swiss lake-dwellings, i. 68, 71; ou
humped cattle, i. 83 ; parentage of
European breeds of cattle, i. 84, ii.
423 ; on " Niata " cattle, i. 93 ; sheep
of the Swiss lake-dwellings, i. 97, ii.
423 ; goats of the Swiss lake-dwell-
ings, i. 105 ; absence of fowls in the
Swiss lake-dwellings, i. 258; on
crossing cattle, ii. 76; differences in
the bones of wild and domesticated
animals, ii. 268 ; decrease in size of
wild European animals, ii. 427.
Rye, wild, De Caniolle's observations
on, i. 330 ; found in the Swiss lake-
dwellings, i. 337 ; common, preferred
by hares and rabbits, ii. 218; less
variable than other cultivated plants,
ii. 241.

Sabine, Mr., on the cultivation of Rosa
spinosissima, i. 391 ; on the cultiva-
tion of the dahlia, i. 393, 394, ii. 249 ;
effect of foreign pollen on the seed-
vessel in Amaryllis vittata, i. 431.

St. Ange, influence of the pelvis on the
shape of the kidneys in birds, ii. 336.

St. Domingo, wild dogs of, i. 28 ; bud-
variation of dahlias in, i. 411.

St. Hilaire, Aug., milk furnished by
cows in South America, ii. 290 ;
husked form of maize, i. 339.

St. John, C, feral cats in Scotland, i.
49 ; taming of wild ducks, i. 292.

St. Valery apple, singular structure
of the, i. 372, artificial fecundation
of the, i. 432.

St. Vitus' Dance, period of appearance
of, ii. 54.

Sachs, Prof, flow of sap, ii. 286.

Sageret, origin and varieties of the
cherry, i. 368, 369 ; origin of varieties
of the apple, i. 372 ; incapacity of
the cucumber for crossing with other
species, i. 383 ; varieties of the melon,
rnd. ; supposed twin-mongrel melon,
i. 427; crossing melons, ii. 86, 109; on
gourds, ii. 86 ; effects of selection ia en-
larging fruit, ii. 202; on the tendency
to depart from type, ii. 228 ; variation
of plants in particular soils, ii. 267.

Salamander, experiments on the, ii.
283, 357, 385 ; regeneration of lost
parts in the, ii. 357-359.

182

SALAMANDRA.

INDEX.

SCOTT.

Salamondra cristata, polydactylism in,
i. 548.

Salisbury, Mr., on the production of
nectarines by peach-trees, i. 361 ; on
the dahlia, i. 393, 394.

Salix, intercrossing of species of, i. 356.

Salix htimilis, galls of, ii. 272, 273.

Salle, feral guinea-fowl in St. Domingo,
i. 310.

Salmon, early breeding of male, ii. 379.

Salter, Mr., on bud-variation in pelar-
goniums, i. 403 ; in the Chrysan-
themum, i. 404 ; transmission of
variegated leaves by seed, i. 409 ;
bud-variation by suckei's in Phlox, i.
410; application of selection to bud-
varieties of plants, i. 443 ; accumu-
lative effect of changed conditions of
life, ii. 249 ; on the variegation of
strawberry leaves, ii. 264 ; on pollen
within ovules, ii. 387.

Salter, S. J., hybrids of Gallus son-
neratii and the common fowl, i. 246,
ii. 19; crossing of races or species of
rats, ii. 65.

Salvin, habits of the jackal, i. 25 ;
mutilation inherited in mot-mot, i.
470.

SAMESREUTHERjOn inheritance in cattle,
i. 455.

Sandford. See Dawkins.

Sanson, M., origin of the horse, i. 54 ;
lumbar vertebra of pigs, i. 77.

Sap, ascent of the, ii. 286.

Saponaria calabrica, i. 463.

Saporta, on Pistacia, i. 431.

Sardinia, ponies of, i. 54.

Sars, on the development of the
hydroida, ii. 364.

Satiation of the stigma, i. 434, 435.

Saturnia pyri, sterility of, in confine-
ment, ii. 141.

Saul, on the management of prize
gooseberries, i. 378.

Sauvigny, varieties of the gold-fish, i.
312.

Savages, their indiscriminate use of
plants as food, i. 325-327 ; fondness
of, for taming animals, ii. 144.

Savi, effect of foreign pollen on maize,
i. 430.

Saxifraga geum, ii. 150.

Sayzid Mohammed Musari, on car-
rier-pigeons, i. 148 ; on a pigeon

which utters the sound " Yahu," i.
163.

Scanderoons (pigeons), i. 149, 150.

Scania, remains of Bos frontosus found
in, i. 85.

Scapula, characters of, in rabbits, i.
129 ; in fowls, i. 282 ; in pigeons, i.
177 ; alteration of, by disuse, '\u
pigeons, i. 184.

Scarlet fever, ii. 272.

Schaaffhausen on the horses repre-
sented in Greek statues, ii. 198.

Schleiden, excess of nourishment a
cause of variability, ii. 244.

SCHMERLING, Dr., varieties of the dog
found in a cave, i. 19.

SCHOMBURGK, Sir R., on the dogs of
Indians of Guiana, i. 20, 23, ii. 191 ;
on the musk duck, i. 191 ; bud-
variation in the banana, i. 401 ;
reversion of varieties of the China
rose in St. Domingo, i. 406 ; sterility
of tame parrots in Guiana, ii. 138 ;
on Dendrocygna vidiiata, ii. 140 j
selection of fowls in Guiana, ii. 194.

SCHREIBERS, on Proteus, ii. 287.

SCHUTZE on the Torfschwein, i. 71.

Sciuropterus volucel/a, ii. 1 35.

Sciurus palmarum and cinerea, ii. 135.

SCLATER, P. L., on Asinus tceniopus, i.
65. ii. 16 ; on Asinus indicus, ii. 17 ;
striped character of young wild pigs,
i. 72; osteology of Gallinula nesiotis,
i. 302 ; on the black-shouldered pea-
cock, i. 305-307 ; animals breeding
in Zoological Gardens, ii. 131 ; birds
breeding in Zoological Gardens, ii.
136 ; on the breeding of birds in
captivity, ii. 136, 140.

Scotch fir, local variation of, i. 386.

Scotch kail and cabbage, cross between,
li. 76.

Scott, John, irregularities in the sex
of the flowers of maize, i. 339 ; bud-
variation in Imatophyllum miniatum,
i. 411 ; crossing of species of Verbas-
cum, ii. 84, 85 ; self-sterility of Ver-
bascum, ii. 118; experiments on
crossing Primulce, ii. 87 ; reproduc-
tion of orchids, ii. 114; fertility of
Oncidium divaricatum, ii. 147; accli-
matisation of the sweet pea in India,
ii. 302 ; number of seeds in Acropera
and Gongora, ii. 373.

SCROPE.

INDEX.

SEXUAL.

483

SCROPE, on the Scotch deeihound, ii.
49, 100.

ScUDDER, Dr., on re-growth, ii. 359.

Sebright, Sir John, effects of close
inter-breeding in dogs, ii. 199; care
taken b}-, in selection of fowls, ii. 181.

Secale cereals, ii. 241.

Sedgwick, W., effects of crossing on the
female, i. 436 ; on the " Porcupine
man," i. 448 ; on hereditary diseases,
i. 451 ; hereditary affections of the
eye, i. 453, ii. 54 ; inheritance of poly-
dactylism and anomalies of the ex-
tremities, i, 458, 459 ; morbid uni-
formity in the same family, i. 460 ;
on deaf-mutes, i. 466 ; inheritance of
injury to the eye, i. 469; atavism
in diseases and anomalies of structure,
ii. 8 ; non-reversion to night-blind-
ness, ii. 10 ; sexual limitation of the
transmission of peculiarities in man,
ii. 48, 49 ; on the effects of hard-
drinking, ii. 280 ; inherited baldness
with dericiency of teeth, ii. 319, 320;
occurrence of a molar tooth in place
of an incisor, ii. 375 ; diseases occur-
ring in alternate generations, ii. 396.

Sedillot, on the removal of portions of
bone, ii. 286

Seeds, early selection of, ii. 188 ; rudi-
mentary, in grapes, ii. 306 ; relative
position of, in the capsule, ii. 337.

Seeds and buds, close analogies of, i.
444.

Seemann, B., crossing of the wolf and
Esquimaux dogs, i. 22.

Segregation of characters, i. 425, 439.

Selby, p. J., on the bud-destroying
habits of the bullfinch, ii. 217.

Selection, ii. 176-236 ; methodical, i.
224, ii. 178-195 ; by the ancients
and semi-civilised people, ii. 185-195 ;
of trifling characters, ii. 193-195;
unconscious, i. 224, 227, ii. 158,
195-202 ; effects of, shown by differ-
ences in most valued parts, ii. 202-
205 ; produced by accumulation of
variability, ii. 205-208; natural, as
affecting domestic productions, ii.
169-174, 209-219; as the origin of
species, genera, and other groups, ii.
425-428 ; circumstances favourable
to, ii. 219-226 ; tendency of, towards
extremes, ii. 226-229 ; possible limit

of, ii. 229 ; influence of time on, ii.
230, 232 ; summary of subject, ii.
234, 236 ; effects of, in modifying
breeds of cattle, i. 96; in preserving
the purity of breeds of sheep, i.
103, 104; in producing varieties of
pigeons, i. 222-229 ; in breeding
fowls, i. 244, 245 ; in the goose, i.
305; in the canary, i. 311; in the
gold-fish, i. 312: in the silkworm, i.
316, 317 ; contrasted in cabbages and
cereals, i. 341 ; in white mulberry, i.
354 ; on gooseberries, i. 378 ; applied
to wheat, i. 335, 336 ; exemplified
in carrots, &c., i. 345 ; in potato, i.
351 ; in the melon, i. 383 ; in flower-
ing plants, i. 388 ; in the hyacinth, i.
395 ; applied to bud-varieties of
plants, i. 443 ; illustrations of, ii.
416-424.

Selection, sexual, ii. 51.

Self-impotence in plants, ii. 112-
122; in individual plants, ii. 117-
120; of hybrids, ii. 158.

Selwyn, Jlr., on the Dingo, i. 26.

Selys-Longchamps, on hybrid ducks,
i. 199, ii. 20, 140; hybrid of the
hook-billed duck and Egyptian goose,
i. 296.

Seringe, on the St. Vale'ry apple, i. 371.

Serpent melon, i. 383, ii. 324.

Serres, Olivier de, wild poultry in
Guiana, i. 249.

Sesamum, white-seeded, antiquity of
the, ii. 425.

Setaria, found in the Swiss lake-dwell-
ings, i. 335.

Settegast, sheep poisoned by buck-
wheat, ii. 331.

Setters, degeneration of, in India, i.
39 ; Youatt's remarks on, i. 43.

Sex, secondary characters of, latent, ii.
26, 27 ; of parents, influence of, on
hybrids, ii. 255.

Sexual characters, sometimes lost in
domestication, ii. 50.

Sexual limitation of characters, ii. 47-
51.

Sexual peculiarities, induced by do-
mestication in sheep, i. 98 ; in fowls,
i. 264-267 ; transfer of, i. 268-270.

Sexual variability in pigeons, i. 169,
170.

Sexual selection, ii. 51.

484

SHADDOCK.

INDEX.

SIZE.

Shaddock, i. 355.

Shailer, Mr., on the moss-rose, i. 405.

Shan ponies, striped, i. 61.

Shanghai fowls, i. 237.

Shanghai aheep, their fecundity, i.
101.

Sheep, disputed origin of, i. 97 ; early-
domestication of, i. 98 ; large-tailed,
i. 98, 102, ii. 269 ; variations in
horns, mammae, and other characters
of, i. 99; sexual characters of, induced
by domestication, ibid. ; adaptation
of, to climate and pasture, i. 100,
101 ; periods of gestation of, i. 101 ;
effect of heat on the fleece of, i. 102,

103, ii. 268 ; effect of selection on, i.
103-105; "ancon"or "otter" breeds
of, i. 104; " Mauchamp-merino," i.

104, 105; cross of German and
merino, ii. 66 ; black, of the Taren-
tino, ii. 212; Karakool, ii. 268;
Jaffna, with callosities on the knees,
ii. 292 ; Chinese, ii. 306 ; Danish, of
the Bronze period, ii. 423 ; polydac-
tylism in, i. 459 ; occasional pro-
duction of horns in hornless breeds
of, ii. 3 ; reversion of colour in, ibid. ;
influence of male, on oflspi'ing, ii. 45 ;
sexual differences in, ii. 49 ; influence
of crossing or segregation on, ii. 63,
73, 80, 81 ; interbreeding of, ii. 98,
99 ; effect of nourishment on the
fertility of, ii. 90 ; value of, cross-
bred, ii. 99 ; diminished fertility
of, under certain conditions, ii. 145 ;
unconscious selection of, ii. 198 ;
natural selection in breeds of, ii. 210,
212; reduction of bones in, ii. 228 ;
individual differences of, ii. 238 ;
local changes in the fleece of, in Eng-
land, ii. 268 ; partial degeneration of,
in Australia, ibid. ; correlation of
horns and fleece in, ii. 318; feeding
on flesh, ii. 293 ; acclimatisation of,
ii. 296 ; mountain, resistance of, to
severe weather, ii. 303 ; white, poi-
soned hj Hypericum crispurn, ii. 331.

Sheep dogs, resembling wolves, i. 24 ;

mutilated tail inherited, i. 470.
Shells, sinistral and dexti-al, ii. 28.
Shirley, E. P., on the fallow-deer, ii.

81, 99.
Shirreff, Mr., new varieties of wheat,

i. 332, 334; on crossing wheat, ii.

83 ; variability of wheat, i. 410 ;
continous variation of wheat, ii. 228.

Short, D., hybrids of the domestic cat
and Felis ornata, i. 47.

SlAM, cats of, i. 46 ; horses of, i. 59.

Siberia, northern range of wild horses
in, i. 56.

Sichel, J., on the deafness of white
cats with blue eyes, ii. 323.

Sidney, S., on the pedigrees of pigs,
i. 447 ; on cross-reversion in pigs, ii.
8 ; period of gestation in the pig, i.
77 ; production of breeds of pigs by
intercrossing, i. 82, ii. 73 ; fertility
of the pig, ii. 90 ; effects of inter-
breeding on pigs, ii. 101-102; on the
colours of pigs, ii. 195, 214.

Siebold, on the sweet potato, ii. 209.

Siebold, Carl von, on parthenogenesis,
ii. 353.

Silene, contabescence in, ii. 149.

Silk-fowls, i. 242, ii. 42, 44.

Silk-moth, Arrindy, ii. 296, 303 ;
Tarroo, ii. 141.

Silk-moths, i. 316-321 ; domesticated,
species of, i. 316 ; history of, i. 317
causes of modification in, ibid.
differences presented by, i. 317-321
crossing of, ii. 76 ; disease in, ii. 213
effects of disuse of parts in, ii. 288
selection practised with, ii. 181, 183
variation of, ii. 222; parthenogenesis
in, ii. 357.

Silkworms, variations of, i. 316-318;
yielding white cocoons, less liable to
disease, ii. 330.

Silver-Grey rabbit, i. 112, 114, 125.

Simon, on the raising of eggs of the
silk-moth in China, ii. 181.

Simonds, J. B., period of maturity in
various breeds of cattle, i. 90; differ-
ences in the periods of dentition in
sheep, i. 100 ; on the teeth in cattle,
sheep, &c., ii. 313 ; on the breeding
of superior rams, ii. 180.

Simpson, Sir J., regenerative power of
the human embryo, ii. 358.

Siredon, breeding in the branchiferous

stage, ii. 379.
Siskin, breeding in captivity, ii. 1 37.
Sivatherium, resemblance of the, to

Niata cattle, i. 93.
Size, diflference of, an obstacle to cross-
ing, ii. 79.

SKIN.

INDEX.

SPENCER.

485

Skln^, and its appendages, homologous,
ii. 317 ; hereditary atiections of the,
ii. 55.

Skirving, R. S., on pigeons settling on
trees in Egypt, i. 190.

Skull, characters of the, in breeds of
dogs, i. 35 ; in breeds of pigs, i. 74 ;
in rabbits, i. 121-126,135; in breeds
of pigeons, i. 172, 173; in breeds of
fowls, i. 273-279; in ducks, i. 296,
297.

Skull and horns, correlation of the, ii.
327.

Skylark, ii. 137,

Sleeman, on the cheetah, ii. 133.

Sloe, i. 366.

Small-pox, ii. 372.

Smiter (pigeon), i. 164.

Smith, Sir A., on Caffrarian cattle, i.
91 ; on the use of numerous plants
as food in South Africa, i. 325.

Smith, Colonel Hamilton, on the odour
of the jackal, i. 31; on the origin of
the dog, i. 16 ; wild dogs in St.
Domingo, i. 28 ; on the Thibet mas-
titi and the alco, i. 29 ; development
of the fifth toe in the hind feet of
mastiffs, i. 37 ; difl'erences in the
skull of dogs, i. 35 ; history of the
pointer, i. 44; on the ears of the
dog, ii. 291 ; on the breeds of horses,
1. 51 ; origin of the horse, i. 53 ;
dappling of horses, i. 58 ; striped
horses in Spain, i. 61; original colour
of the horse, i. 63 ; on horses scraping
away snow, i. 56 ; on Asinus hemionus,
ii. 17 ; feral pigs of Jamaica, i. 80,
81.

Smith, Sir J. E., production of necta-
rines and peaches by the same tree,
i. 361 ; on Viola amoena, i. 392 ;
sterility of Vinca minor in England,
ii. 154.

Smith, J., development of the ovary in
Bonatea speciosa by irritation of the
stigma, i. 434.

Smith, N. H., influence of the bull
*' Favourite" on the breed of Short-
horn cattle, ii. 40.

Smith, W., on the intercrossing of
strawberries, i. 372.

Snake- rat, ii. 64, 65.

Snakes, form of the viscera in, ii. 336.

Snapdragon, bud-variation in, i. 407 ;

non-inheritance of colour in, i. 464 ;
peloric, crossed with the normal
form, ii. 46, 71; asymmetrical
variation of the, ii. 314.

Soil, adaptation of plums to, i. 368;
influence of, on the zones of pelar-
goniums, i. 390; on roses, i. 391 ; on
the variegation of leaves, i. 409 ; ad-
vantages of change of, ii. 127-130.

Soil and climate, eii'ects of, on straw-
berries, i. 375.

Solanum, non-intercrossing of species of,
ii. 68.

Solanum tuberosum, i. 350, 351, 410.

Solid-hoofed pigs, i. 78.

Solomon, his stud of horses, i. 57.

Somerville, Lord, on the fleece of
Merino sheep, i. 103; on crossing
sheep, ii. 99 ; on selection of sheep,
ii. 179 ; diminished fertility of Merino
sheep brought from S^iain, ii. 14 5.

Sooty fowls, i. 242, 269.

Sorghum, i. 396.

Soto, Ferdinand de, on the cultivation
of native plants in Florida, i. 329.

Spain, hawthorn monogynous in, i. 387.

Spallanzani, on feral rabbits in Li-
pari, i. 118; experiments on sala-
manders, ii. 283, 357, 358 ; experi-
ments in feeding a pigeon with meat,
ii. 294.

Spaniels, in India, i. 39 ; King Charles's,
i. 43 ; degeneration of, caused by in-
terbreeding, ii. 100.

Spanish fowls, i. 237, 263, 268; figured,
1. 238; early development of sexual
characters in, i. 263 ; furculum of,
figured, i. 281.

Species, difficulty of distinguishing
from varieties, i. 4 ; conversion of
varieties into, i. 5 ; origin of, by
natural selection, ii. 410; by mutual
sterility of varieties, ii. 169-172.

Spencer, Lord, on selection in breeding,
ii. 179.

Spencer, Herbert, on the " survival of
the fittest,' i. 6 ; increase of fertility
by domestication, ii. 89 ; on life, ii.
130, 161 ; changes produced by ex-
ternal conditions, ii. 270; effects of
use on organs, ii. 286 ; ascent of the
sap in trees, ihid. ; correlation ex-
emplified in the Irish oik, ii. 327, 328 ;
on "physiological i nits," ii. 370;

186

SPERMATOPHORES.

INDEX.

STRIPES.

antagonism of growth and reproduc-
tion, ii. 379.

SPERMATOPHORES of the cephalopoda,
ii. 379.

Spermatozoids, ii. 356, 857,

Sphingid^, sterility of, in captivity,
ii. 141.

Spinola, on the injurious effect pro-
duced by flowering buckwheat on
white pigs, ii. 331.

Spitz dog, i. 32.

Spooner, W. C, cross-breeding of
sheep, i. 104-, ii. 73, 74, 99 ; on the
effects of crossing, ii. 74, 75 ; on
crossing cattle, ii. 96; individual
sterility, ii. 146.

Spores, reproduction of abnormal forms
by, i. 408.

Sports, i. 397 ; in pigeons, i. 223.

Spot pigeon, i. 163, 217.

Sprengel, C. K., on dichogamous plants,
ii. 68 ; on the hollyhock, ii. 86 ; on
the functions of flowers, ii. 159.

Sproule, Mr., transmission of hare-lip,
i. 466.

Spurs, of fowls, i. 267 ; development
of, in hens, ii. 310.

Squashes, i. 381.

Squinting, hereditary, i. 453.

Squirrels, generally sterile in cap-
tivity, ii. 135.

Squirrels, flying, breeding in confine-
ment, ii. 135.

" Staarhalsige Taube," i. 169.

Stag, one-horned, supposed heredity of
character in, i. 456 ; degeneracy of,
in the Highlands, ii. 192.

Stamens, occurrence of rudimentary,
ii. 307 ; conversion of, into pistils, i.
389 ; into petals, ii. 386.

Staphylea, ii. 152.

Steenstrup, Prof., on the dog of the
Danish Middens, i. 18; on the ob-
liquity of flounders, ii. 28.

Steinan, J., on hereditary diseases, i.
451, ii, 55.

Stephens, J. F., on the habits of the
Bombycidae, i. 294.

Sterility", in dogs, consequent on close
confinement, i. 33 ; comparative, of
crosses, ii. 82, 83 ; from changed
conditions of life, ii. 130-149; oc-
curring in the descendants of wild
animals bred in captivity, ii. 143 ;

individual, ii. 146 ; resulting from
propagation by buds, cuttings, bulbs,
&c., ii. 153; in hybrids, ii. 162-165,
383, 405, 406 ; in specific hybrids of
pigeons, i. 203 ; as connected with
natural selection, ii. 169-172,

Sternum, characters of the, in rabbits,
i. 128; in pigeons, i. 177, 184; in
fowls, i. 282, 288; effects of disuse
on the, i. 180, 184-188.

Stewart, H., on hereditary disease, ii. 55.

Stigma, variation of the, in cultivated
Cucurbitaceae, i. 382 ; satiation of
the, i. 434, 435.

Stockholm, fruit-trees of, ii. 297.

Stocks, bud-variation in, i. 407 ; effect
of crossing upon the colour of the
seed of, i. 429 ; true by seed, i. 463 ;
crosses of, ii. 71 ; vari'^ties of, pro-
duce! by selection, ii. 204 ; reversion
by the upper seeds in the pods of, ii.
340.

Stockton, Hough, direct action of
pollen, i. 431.

Stokes, Prof., calculation of the chance
of transmission of abnormal peculi-
arities in man, i. 449.

Stolons, variations in the production
of, by strawberries, i. 375.

Stomach, structui-e of the, affected by
food, ii. 292.

Stone in the bladder, hereditary, i. 452,
ii. 55.

Stonehenge, on maturity of the dog,
i. 36 ; inherited effects of injury, i.
470 ; cross between bulldog and
greyhound, ii. 65 ; close interbreed-
ing of greyhound, ii. 100 ; floetness
of race-horses, ii. 229.

Storer, J., pedigree of cattle, ii. 96,

Strawberries, i. 372-376 ; remark-
able varieties of, i. 374, 375; haut-
bois dioecious, i. 375; selection in, ii.
184; probable further modification
of. ii. 229 ; variegated, effects of soil
on. ii. 263.

Strickland, A., on the domestication
of Anser ferus, i. 303 ; on the colour
of the bill and legs in geese, i. 304.

Strictcenas, i. 192.

Stripes on young of wild swine, i. 80 ;
of domestic pigs of Turkey, West-
phalia, and the Zambesi, ibid. ; of
feral swine of Jamaica and Ne»

STRIX.

INDEX.

TEETH.

487

Granada, i. 81 ; of fruit and flowers,

i. 430, ii. 11 ; in horses, i, 58-63 ; in

the ass, i. 66, 67 ; production of, bj

crossing species of Equidae, ii. 16, 17.
Strix groUlaria, ii. 292.
Strix passerina, ii. 137.
" Strupp-Taube," i. 163.
Struthers, D., osteology of the feet in

solid-hoofed pigs, i. 78 ; on poly-

dactylism, i. 457, 458.
Sturm, prepotency of transmission of

characters in sheep and cattle, ii. 41 ;

absorption of the minority in crossed

races, ii. 65 ; correlation of twisted

horns and curled wool in sheep, ii.

318.
Sub-species, wild, of Golumha livia and

other pigeons, i. 214.
Succession, geological, of organisms, i.

11.
Suckers, bud-variation by, i. 409.
Sugar-cane, sterility of, in various

countries, ii. 1 53 ; sporting of, i. 410 ;

white, liability of, to disease, ii. 213.

330.
Suicide, hereditary tendency to, i. 451,

ii. 55.
SULIVAN, Admiral, on the horses of the

Falkland Islands, i. 55; wild pigs of

the Falkland Islands, i. 80 ; feral cattle

of the Falkland Islands, i. 89, 96 ;

feral rabbits of the Falkland Islands,

i. 117.
Sultan fowl, i. 240, 267.
Sus indicus, i. 68, 70-72, ii. 89.
Sus pliciceps (figured), i. 72.
Sus scrofa, i. 68, 69, ii. 89.
Sus icrofa paltcstris, i. 71-
Stis sennariensis, i. 71.
Sus vittatus, i. 70.

Swallows, a breed of pigeons, i. 64.
Sweet peas, ii. 68 ; crosses of, ii. 71 ;

varieties of, coming true by seed, i.

463 ; acclimatisation of, in India, ii.

302.
Sweet William, bud-variation in, i. 406.
SwiNHOE, R., on Chinese pigeons, i.

155, 216; on striped Chinese horses,

i. 61; ou the japanned peacock, i. 30(3.
Switzerland, ancient dogs of, i. 19;

pigs of, in the Neolithic period, i. 71 ;

goats of, i. 105.
Sycamore, pale-leaved variety of the,

ii. 324.

Si'KES, Colonel, on a pariah dog with
crooked legs, i. 17 ; on small Indian
asses, i. 65 ; on Gallus sonneratii, i.
245 ; on the voice of the Indian Kulm
cock, i. 272 ; fertility of the fowl in
most climates, ii. 144.

Symmetry, hereditary departures from,
1. 456.

Symphytum, variegated, i. 410.

Syphilis, hereditary, ii. 325.

Syria, asses of, i. 65.

Syrin/a persica, chinensis, and vulyaris,
ii. 148.

Tacitus, on the care taken by the Celts

in breeding animals, ii. 187.
Taqetes signata, dwarf variety of, i.

463.
Tahiti, varieties of cultivated plants

in, ii. 243.
Tail, never curled in wild animals, ii.

291 ; rudimentary in Chinese sheep,

ii. 306.
Tail-feathers, numbers of, in breeds

of pigeons, i. 167, 168; peculiarities

of, in cocks, i. 267 ; variability of, in

fowls, i. 270 ; curled, in Anas boschas,

and tame drakes, i. 295.
Tait, Lawson, presence of hairs and

teeth in ovarian tumours, ii. 365.
Talent, hereditary, i. 451.
Tankerville, Earl of, on Chillingham

cattle, i. 88, ii. 97.
Tanner, Prof., el^ects of disuse of parts

in cattle, ii. 289.
Tapir, sterility of the, in captivity, ii.

133.
Targioni-Tozzetti, on cultivated

plants, i. 323; on the vine, i. 352;

varieties of the peach, i. 363 ; origin

and varieties of the plum, i. 367 ;

origin of the cherry, i. 368 ; origin

of roses, i. 390.
Tarsus, variability of the, in fowls, i.

272 : reproduction of the, in a thrush,

ii. 358.
Tartars, their preference for spiral-
horned sheep, ii. 194.
Tavernier, abundance of pigeons in

Peisia, i. 215.
Taxus baccata, i. 461.
Taylor, Mr., potato-grafting, i. 420.
Teebay, Mr., reversion m fowls, ii. 12.
Teeth, number and position of, in dogs,

188

TIGK'IMEIEE.

INDEX.

TH0KN8.

i. 35 ; deficiency of, in naked Turkish
dogs, i. 36 ; period of appearance of,
in breeds of dogs, ibid.; precocity of,
in highly-bred animals, ii. 318 ; cor-
relation of, with hair, ii. 319 ; double
row of, with redundant hair, in Julia
Pastrana, ii. 321 ; affected in form
by hereditary syphilis and by pulmo-
nary tubercle, ii. 325; developed on
the palate, ii. 385.

Tegetmeier, Mr., on a cat with mon-
strous teeth, i. 50 ; on a swift-like
pigeon, i. 165; on sexual colours, i.
J 70; naked young of some pigeons,
1. 179 ; fertility of hybrid pigeons, i.
201; on white pigeons, ii. 215; re-
version in crossed breeds of fowls, i.
251-256; chicks of the white silk-
fowl, i. 261; development of the
cranial protuberance in Polish fowls,
i. 262; on the skull in the Polish
fowl, i. 268, 275 ; on the intelligence
of Polish fowls, i. 276; correlation
of the cranial protuberance and crest
in Polish fowls, i. 289 ; development
of the web in the feet of Polish fowls,
i. 272 ; early development of several
peculiarities in Spanish cocks, i. 263 ;
on the comb in Spanish fowls, i. 266 ;
on the Spanish fowl, ii. 296 ; varieties
of game-fowls, i. 264; pedigrees of
game-fowls, 1. 447 ; assumption of
female plumage by a game-cock, i.
265 ; natural selection in the game-
cock, ii. 210; pugnacity of game-
hens, i. 268 ; length of the middle
toe in Cochin fowls, i. 272 ; origin of
the Sebright bantam, ii. 29 ; differ-
ences in the size of fowls, i. 270;
effect of crossing in fowls, ibid. ; ii.
74 ; effects of interbreeding in fowls,
ii. 105, 106 ; incubation by mongrels
of non-sitting races of fowls, ii. 18;
inverse correlation of crest and comb
in fowls, i. 288 ; occurrence of pen-
cilled feathers in fowls, ii. 14 ; on a
variety of the goose from Sebastopol,
i. 304; on the fertility of the pea-
hen, ii. 91 ; on the intercrossing of
bees, ii. 107.

Temminck, origin of domestic cats, i. 46;
origin of domestic pigeons, i. 189 ; on
Columba guinea, i. 192; on Coluwba
leucocephala, ibid. ; asserted reluc-

tance of some breeds of pigeons to
cross, 1. 202 ; sterility of hybrid
turtle-doves, 1. 203 ; variations of
Gallus bankiva, i. 247 ; on a buff-
coloured breed of turkeys, i. 309 ;
number of eggs laid by the peahen,
ii. 91 ; breeding of guans in captivity,
ii. 139 ; behaviour of grouse in cap-
tivity, ibid. ; sterility of the partridge
in captivity, ibid.

Tendrils in Cucurbitacea?, i. 381, ii.
306.

Tennent, Sir J. E., on the goose, i.
302 ; on the growth of the apple iu
Ceylon, ii. 266 ; on the Jaffna sheep,
ii. 292.

Teredo, fertilisation in, ii. 356.

Terriers, wry-legged, ii. 232 ; white,
subject to distemper, ii. 330.

Teschemacher, on a husked form of
maize, i. 339.

Tessier, on the period of gestation ot
the dog, i. 30 ; of the pig, i. 77 ; in
cattle, i. 90 ; experiments on change
of soil, ii. 129.

Tetrao, breeding of species of, in capti-
vity, ii. 139.

Tetrapteryx paradisea, ii. 140.

Tcucrium campanulatum, pelorism in, ii.
337.

Texas, feral cattle in, i. 89.

Theognis, his notice of the domestic
fowl, i. 258.

Theophrastus, his notice of the peach,
ii. 299.

Thesium, ii. 274.

Thompson, IVIr., on the peach and nec-
tarine, i. 363 ; on the varieties of the
apricot, i. 365 ; classification of varie-
ties of cherries, i. 369 ; on the "Sister
ribston - pippin," i. 372; on the
A-arieties of the gooseberry, i. 376,
377.

Thompson, William, on the pigeons of
Islay, i. 193 ; feral pigeons in Scot-
land, i. 199 ; colour of the bill and
legs in geese, i. 304 ; breeding of
Tetrao scothis in captivity, ii. 139;
destruction of black fowls by the
osprey, ii. 215,

Thorn, grafting of earlv and late, i,
386 ; Glastonbury, i. 387.

Thorns, reconversion of, nto branches,
in pear trees, ii. 310

THRUSH.

INDEX.

TUMOURS.

489

Thrush, asserted reproduction of the

tarsus in a, ii. 358.
Thuja petidula or flifonnis, a variety of

1\ orientalis, i. 386.
Thuret, on the division of the zoospores

of an alga, ii. 372.
Thwaites, G. H., on the cats of Ceylon,

i. 48 ; on a twin seed of Fuchsia coc-

cinea and fulgens, i. 426.
TiBURTius, experiments in rearing wild

ducks, i. 292.
Tiger, rarely fertile in captivity, ii.

133.
Tigridla conchiflora^ bud- variation in, i.

412.
Time, importance of, in the production

of races, ii. 230.
TlxzMANN, self-impotence in the potato,

ii. 118.
Tissues, affinity of, for special organic

substances, ii. 375.
Titmice, destructive to thin-shelled

walnuts, i. 379 ; attacking nuts, ibid.;

attacking peas, ii. 216.
Tobacco, crossing of varieties of,

ii. 87; cultivation of, in Sweden, ii.

298.
Tobolsk, red-coloured cats of, i. 49.
Toes, relative length of, in fowls, i.

272 ; development of fifth, in dogs, ii.

309.
TOLLET, Mr., his selection of cattle, ii.

183.
Tomato, ii. 68.

Tomes, inheritance of dental malforma-
tions, i. 452.
Tomtits. See Titmice.
Tongue, relation of, to the beak in

pigeons, i. 77.
Tooth, occurrence of a molar, in place

of an incisor, ii. 385.

" TORFSCHWEIN," i. 71.

Trail, R., on the union of half-tubers
of different kinds of potatoes, i.
420.

Trees, varieties of, suddenly pioduced,
i. 384 ; weeping or pendulous, i. 385 ;
fastigate or pyramidal, ibid. ; with
variegated or changed foliage, ibid. ;
early or late in leaf, i. 386 ; forest,
non-application of selection to, ii.
223.

"Trembleur" (pigeons), i. 153.

Trembley, on reproduction in Hydra,
ii. 352.

"Trevoltixi" silkworms, i. 318, 319.

Trichosanthes anguina, i. 383.

Tricks, inheritance of, i. 450,451.

Trifolium minus and repcms, ii. 147.

Primorphic plants, conditions of repro-
duction in, ii. 165-169.

Tristram, H. B., selection of the drome-
dary, ii. 190.

Triticum dicoccum, i. 337.

Triticum monococcum, i. 337.

Triticum spelta, i. 337.

Triticum turgidum, i. 337.

Triticum vulgare, wild iu Asia, i. 330.

Triton, breeding in the branchiferous
stage, ii. 379.

" Trommel-Taube," i. 162.

"Tronfo" pigeon, i. 151.

Tropoeolum, ii. 11.

Tropneolum minus and m^ijus, reversion
in hybrids of, i. 425.

Troubetzkoy, Prince, experiments
with peai'-trees at Moscow, ii. 297.

Trousseau, Prof., pathological resem-
blance of twins, ii. 239.

Trumpeter pigeon, i. 162; known in
1735, i. 217.

TsCHARNER, H. A. DE, graft-hybrid pro-
duced by inosculation in the vine, i.
419.

TscHUDi, on the naked Peruvian dog,
i. 24; extinct varieties of maize
from Peruvian tombs, i. 338, ii.
421.

Tubers, bud-variation by, i. 409-411.

TuCKERMAN, Mr., Sterility of Carex
rigida, ii. 154.

Tufted ducks, i. 295.

Tulips, variability of, i. 394 ; bud-vana-
tion in, i. 411,412; influence of soil
in "breaking," i. 411.

Tumbler pigeon, i. 156-161; short-
faced, figured, i. 160; skull figured,
i. 172; lower jaw figured, i. 173;
scapula and furcuium figured, i. 176 ;
early known in India, i. 217 ; history
of, i. 219; sub-breeds of, i. 230;
young, unable to break the egg-shell,
ii. 211 ; probable further modification
of, ii. 229.

"Tummler" (pigeons), i. 156.

TuMOUPuS, ovarian, occurrence of hairs

i90

TDKBIT.

INDEX.

VARIETIES.

and teeth in, ii, 3G5 ; polypoid, origin
of, ii. 377.

TURBiT (pigeon), i. 156, 219„

Turkey, domestic, origin of, i. 308;
crossing of, with North American wild
turkey, i. 308, 309 ; breeds of, i. 308;
crested white cock, i. 309 ; wild, cha-
i-acters of, i. 309, 310; degeneration
of, in India, i. 310; ii. 267; failure
of eggs of, in Delhi, ii. 145 ; feral, on
the Parana, 1. 199 ; change produced
in, by domestication, ii. 250.

Turkey, striped young pigs in, i. 80.

" Turkische Taube," i. 146.

Turner (pigeon), i, 164.

Turner, C, on the hollyhock, i. 86.

Turner, W., on cells, ii. 366.

Turnips, origin of, i. 344 ; reversion in,
ii. 5 ; run wild, ii. 7 ; crosses of, ii. 71,
74; Swedish, preferred by hares, ii.
217 ; acclimatisation of, in India, ii.
302.

Turnspit, on an Egyptian monument,
i. 17 ; crosses of the, ii. 70.

Turtle-dove, white and coloured,
crossing of, ii. 70.

Turtur auritus, hybrids of, with T.
carnbayensis and T. swatensis, i.
203.

Turtur risorius, crossing of, with the
common pigeon, i. 202 ; hybrids of,
with T. vulgaris, ibid.

Turtur suratensis, sterile hybrids of,
with T. vulgaris, i. 203 ; hybrids of,
with T. auritus, ibid.

Turtur vulgaris, crossing of, with the
common pigeon, i. 203 ; hybrid of,
with T. risorius, ibid. ; sterile hybrids
of, with T. suratensis and Ectopistes
migratorius, ibid.

Tusks of wild and domesticated pigs, i.
79, 80.

Tussilago farfara, variegated, i. 410.

Twin-seed of Fuchsia coccinea ami
fulgens, i. 426.

Tyerman, B., on the pigs of the Pacific
Islands, i. 73, ii. 64 ; on the dogs of
the Pacific Islands, ibid.

Tylor, Mr., on the prohibition of con-
sanguineous marriages, ii. 103.

Udders, development of the, ii. 290.
UleXj double-flowered, ii, 151.

Ulmus campestris and effusa, hybrids of,

ii. 111.
Uniformity of character, maintained

by crossing, ii. 62-67.
Units of the body, functional independ-
ence of the, ii. 364-3•^6.
Unity or plui'ality of origin of organisms,

i. 13.
Urea, secretion of, ii. 375.
Use and disuse of parts, etfects of, ii. 285,

293, 345, 346, 413, 414 ; in rabbits, i.

129-134; in ducks, i. 299-301.
Utility, considerations of, leading to

uniformity, ii. 227.

Valentin, experimental production of
double monsters by, ii. 385.

Vallota, ii. 121.

Van Beck, Barbara, a hairy-faced
woman, i. 448.

Van Mons, on wild fruit-trees, i. 329,
ii. 248 ; production of varieties of the
vine, i. 353 ; correlated variability
in fruit-trees, ii. 324 ; production of
almond-like fruit by peach-seedlings,
i. 359.

Vanessa, species of, not copulating in
captivity, ii. 141.

Variability, i. 4, ii. 366-369,388-390,
401—416 ; causes of, ii, 237-255 ; coi'-
related, ii. 311-332, 346, 347, 415,
416; law of, equable, ii. 344, 345;
necessity of, for selection, ii. 174;
of selected characters, ii, 225 ; of
multiple homologous parts, ii, 334,

Variation, laws of, ii. 283-348 ; con-
tinuity of, ii. 227 ; possible limita-
tion of, ii. 228, 413, 414 ; in domestic
cats, i, 47-50 ; origin of breeds of
cattle by, i. 91 ; in osteological cha-
racters of rabbits, i. 120-136; of
important organs, i. 382 ; analogous
or parallel, i. 340-343 ; in horses, i.
58 ; in the horse and ass, i. 67 ; in
fowls, i, 255-258 ; in geese, i. 303 ;
exemplified in the production of
fleshy stems in cabbages, t&c, i, 344;
in the peach, nectarine, and apricot,
i, 363, 365 ; individual, in wheat, i.
331.

Variegation of foliage, i. 409, ii. 151.

Varieties and species, resemblance of,
i. 4, ii. 406-408 ; conversion of^ into

VARRO.

INDEX.

VIBGIL.

491

species, i. 5 ; abnormal, ii. 409 ;
domestic, gradually produced, ii. 411.

Varro, on domestic ducks, i. 291 ; on
feral fowls, ii. 7 ; crossing of the
wild and domestic ass, ii. 190.

Vasev, ]Mr., on the number of sacral
vertebrae in ordinary and humped
cattle, i. 83 ; on Hungarian cattle, i.
84.

Vaucher, sterility of Ranunculus
ficaria and Acorus calamus, ii. 154.

Vegetables, cultivated, reversion in,
ii. 7 ; European, culture of, in India,
ii. 152, 153.

Veith, Mr., on breeds of horses, i.
51.

Verbascum, intercrossing of species of, i.
356, ii. 71, 83-85 ; reversion in hy-
brids of, i. 425 ; self-sterility of, ii.
118; contabescent, wild plants of, ii.
149 ; villosity in, ii. 267.

Verbascum austriacum, ii. 117.

Verbascum blattaria, ii. 83, 84.

Verbascum lyc'(nitis, ii. 83, 84, 117.

Verbascum nigrum, ii. 117.

Verbascum phceniceum, ii. 85, 118 ; vari-
able duration of, ii. 295.

Verbascum thaps'is, ii. 84, 118.

Verbenas, origin of, i. 388 ; white,
liability of, to mildew, ii. 213, 330;
scorching of dark, ii. 214, 330 ; effect
of changed conditions of life on, ii.
263.

Verlot, on the dark-leaved barberry,
i. 385 ; inheritance of peculiarities
of foliage in trees, il>id. ; produc-
tion of Rosa cannabifolia by bud-vari-
ation from ii*. alba, i. 406 ; bud-
variation in Aralia trifoliata, i. 408 ;
variegation of leaves, ibid. ; colours
of tulips, i. 412; uncertainty of in-
heritance, i. 461; persistency of
white flowers, i. 463 ; peloric flowers
oi' Linaria, ii. 32 ; tendency of striped
flowers to uniformity of colour, ii. 46 ;
non-intercrossmg of certain allied
plants, ii. 68 :sterilityof Pri/rmtewith
coloured calyces, ii. 150 ; on fertile
proliferous flowers, ibid. ; on the Irish
yew, ii. 228 ; differences in the Ca-
mellia, ii. 238 ; effect of soil on the
variegated strawberry, ii. 263 ; cor-
related variability in pla:its, ii. 324.

Verruca, ii. 28, 394.

Vertebrae, characters of, in rabbits, i.
126-128; in ducks, i. 297, 298;
number and variations of, in pigeons,
i. 174, 175; number and characters
of, in fowls, i. 279-281 ; variability
of number of, in the pig, i. 77.

Yertuch. See Putsche.

" Verugas," ii. 266.

Vespqcius, early cultivation in Brazil,
i. 329.

Vibert's experiments on the cultiva-
tion of the vine from seed, i. 352.

Viburnum opulus, ii. 169, 307.

Vicia safiva, leaflet converted into a
tendril in, ii. 386.

Vicunas, selection of, ii. 192.

Villosity of plants, influenced by dry-
ness, ii. 267.

ViLMORiN, cultivation of the wild
carrot, i. 344, ii. 267 ; colours of
tulips, i. 412 ; uncertainty of in-
heritance in balsams and roses, i.
461 ; experiments with dwarf varie-
ties of Saponaria calabrica and Tagetes
signata, i. 463 ; reversion of flowers
by stripes and blotches, ii. 11 ; on
variability, ii. 250.

Vinca minor, sterility in, ii. 154.

Vine, i. 352-354 ; parsley-leaved, re-
version of, i. 408 ; gratt-hybrid pro-
duced by inosculation in the, i. 419 ;
disease of, influenced by colour of
grapes, ii. 213, 214; influence of
climate, &c., on varieties of the, ii.
267; diminished extent of cultiva-
tion of the, ii. 298 ; acclimatisation
of the, in the West Indies, ii. 304.

Viola, sppcies of, i. 391.

Viola lutea, different coloured flowers
in, i. 440.

Viola tricolor, reversion in, ii. 4, 22.

ViRCHOW, Prof., on the growth of
bones, ii. 284, 377 ; on cellular pro-
liflcation, ii. 85 ; independence of
the elements of the body, ii. 364 ; on
the cell-theory, ii. 366 ; presence of
hairs and teeth in ovarian tumours,
ii. 365 ; of hairs in the brain, ii.
386 ; special affinities of the tissues,
ii. 375 ; origin of polypoid excres-
cences and tumours, ii. 377.

Virgil, on the selection of seed corn, i.

i92

TIRGINIAN.

INDEX.

WEBB.

336, ii. 187 ; of cattle and sheep, ii.
186.

Virginian Islands, ponies of, i. 54.

Vision, hereditary peculiarities of, i.
452, 453 ; in amphibious animals, ii.
208 ; varieties of, ii. 290 ; affections
of organs of, correlated with other
peculiarities, ii. 321.

Vitis vinifera, i. 352-354, 399.

Viverra, sterility of species of, in cap-
tivity, ii. 134.

VOGEL, varieties of the date palm, ii.
243.

VOGT, on the indications of stripes on
blacli kittens, ii. 30.

Voice, ditferences of, in fowls, i. 272 ;
peculiarities of, in ducks, i. 296 ; in-
heritance of peculiarities of, i. 450.

VOLZ, on the history of, the dog, i. 17 ;
ancient history of the fowl, i. 258 ;
domestic ducks unknown to Aristotle,
i. 292; Indian cattle sent to Mace-
donia by Alexander, ii. 186 ; mention
of mules in the Bible, ii. 186 ;
history of the increase of breeds, ii.
231.

Von Berg, on Verbascum phosnicennij
ii. 295.

VooRHELM, G., his knowledge of hya-
cinths, i. 395, ii. 238.

Vrolik, Prof, on polydactylism, i.
457; influence of the shape of the
mother's pelvis on her child's head,
ii. 336.

Wade, droopiug eyelids ti'ansmitted,

i. 452.
Waders, behaviour of, in confinement,

ii. 140.
Wagner, Moritz, oriental dogs, ii.

222.
Wahlenborg, on the propagation of

Alpine plants by buds, runners, bulbs,

&c., ii. 154.
" Wahlverwandischaft " of Gartner,

ii. 164.
Wales, white cattle of, in the tenth

century, i. 89.
Walker, A., on intermarriage, i. 436;

on the inheritance of polydactylism,

i. 458.
Walker, D., advantage of change of

soil to wheat, ii. 128.

Walker, R., reversion in cattle, ii. 8.

Wallace, A. R., on the multiple origin
of the dog, i. 27 ; on a striped
Javanese horse, i. 61 ; on the condi-
tions of life of feral animals, ii. 6 ;
artificial alteration of the plumage
of birds, ii. 269 ; on polymorphic
butterflies, ii. 394 ; on reversion, ii.
41 1 ; on the limits of change, ii. 412.

WallvVCe, Dr., on the sterility of
Sphingidse hatched in autumn, ii.
141.

Wallachian sheep, sexual peculiari-
ties in the horns of, i. 99.

Wallflower, bud-variation in, i. 407.

Wallich, Dr., on Thuja pendula or
filiformis, i. 386.

Walnuts, i. 379, 380; thin-shelled,
attacked by tomtits, i. 379 ; ii. 216 ;
grafting of, ii. 247.

Walsh, B. D., on attacks of insects, i.
371; on galls, ii. 272, 273; his
" Law of equable variability," ii.
344, 345.

Walther, F. L., on the history of the
dog, i. 17; on the intercrossing of
the zebu and ordinary cattle, i. 87.

Waring, Mr., on individual sterility,
ii. 146.

Waterer, Mr., spontaneous produc-
tion of Cytisus alpino-laburnum, i.
416.

Waterhouse, G. R., on the winter-
colouring oi Lepus vari ibilis, i. 115.

Waterton, C, production of tailless
foals, i. 56 ; on taming wild ducks,
i. 292 ; on the wildness of half bred
wild ducks, ii. 20 ; assumption of male
characters by a hen, ii. 26.

Watson, H. C, on British wild fruit-
trees, i. 329 ; on the non-variation of
weeds, i. 335 ; origin of the pluni, i.
366 ; variation in Pyrus malus, i.
370 ; on Viola amcena and tricolor, i.
392 ; on reversion in Scotch kail, ii.
35 ; fertility oi Draba sylvestris when
cultivated, ii. 147 ; on generally
distributed British plants, ii. 275.

Wattles, rudimentary, in some fowls,
ii. 306.

Watts, Miss, on Sultan fowls, i. 240.

Webb, Jonas, interbreeding of sheep,
ii. 98.

WhBEtl.

INDEX.

WILLIAMS.

493

vVebes, effect of the shape of the
mo her's pelvis on her child's head,

11. 33(3.

VVedderburn, ]\Ir., correlation of
teeth and hair, ii. 319.

Weeds, supposed necessity for their
modification, coincidently with culti-
vated plants, i. 335.

Weeping varieties of trees, i. 385.

Weeping habit of trees, capricious in-
heritance of, i. 461, 462.

Weev'^il, injury done to stone-fruit by,
in North America, ii. 217.

Weijenbergh, on parthenogenesis, ii.
356.

Weir. H., large litter of pigs, ii. 90.

Weir, .Ienner, on the ja|)anned pea-
cock, i. 306 ; mare and quagga, i.
435 ; wildness of mule siskins, ii. 20.

Weismann, I'rof., reversion from un-
natural conditions, ii. 25; isolation,
ii. 262 ; dimorphic butterflies, ii.
271 ; causes of variability, ii. '282.

Welsh cattle, descended from Bos long,,
frons, i. 85.

West indies, feral pigs of, i. 80; effect
of climate of. upon sheej), i. 102.

Western, Lord, change effected by, in
pigs, i. 82, 101 ; in the sheej), ii. 182.

Westphalia, striped young pigs in, i.
80.

Westwood, J. 0., on peloric flowers of
Calceolaria, ii. 338.

Wetherell, Mr., on inheritance of
mutilations, i. 466.

Whately, Archbishop, on grafting
e;irly and late thorns, i. 386.

Wheat, specific unity or diversity of,
i. 329, 330, 334, 335 ; Hasora, i. 335 ;
piesence or absence of barbs in, i.
331 ; Godron ou variations in, ibid. ;
varieties of, i. 331, 332 ; effects of
soil and climate on, i. 333 ; deteriora-
tion of, i. 334 ; crossing of varieties of,
iV(/., ii. 74, 83, 110; in the Swiss
lake-dwellings, i. 335-337 ; selection
applied to. i. 336. ii. 184; increased
fi.'rtility of hybrids of, with A£yilops,
ii. 88 ; advantage of change of
soil to, ii. 128 ; differences of, in
various parts of India, ii. 149; con-
tinuous variation in, ii. 184 ; red,
bardiness of, ii. 215, 330; Fenton,

43

11.218; natural selection In, ibid.;
varieties of, found wild, Ii. 248 ;
effects of change of climate on, ii.
297 ; ancient variety of, ii. 425.

Whitby, JNlrs., on the markings of
silkworms, 1. 318; on the silk-moth,
i. 319.

White, Mr., reproduction of supernu-
merary digits after amjxitation, i.
459 ; time occupied in the blending
of crossed races, ii, 64.

White, Gilbert, vegetable diet of dogs,
ii. 293.

White and white-spotted animals, lia-
bility of, to disease, ii. 330, 331.

White flowers, most truly reproduced
by seed, i. 463.

WiCHURA, Max, on hybrid willows, ii.
25, 111, 255; analogy between the
pollen of old-cultivated plants and
of hybrids, ii. 256.

WlCKiNG, Mr., inheritance of the pri-
mary characters of Columba tivia in
cross-bred pigeons, i. 210 ; production
of a white head in almond tumblers,
ii. 183.

WiCKSTED, ]\Ir., on cases of individual
sterilitv, ii. 146.

WiEGMANN, spontaneous cro.ssing of
blue and white peas, i. 428 ; crossing
of varieties of cabbage, ii. 110; on
contabescence, ii. 149.

Wight, Dr.. sexual sterility of plants
propagated by buds, &c,, ii. 153.

WiLCKENS, Dr., effect of previous Im-
pregnation, i. 436'; alpine breeds, ii.
290 ; drooping ears, ii. 291 ; correla-
tion of hair and horns, ii. 318.

Wilde, Sir W. R., occurrence of Bos
frontosus and longifrons in Irish cran-
noges, i. 85 ; attention paid to breeds
or' animals by the ancient Irish, ii.
187.

Wilder, Dr. B., on the brain of dogs,
i. 35 ; supernumerary digits i. 457.

WiLDMAN, on the dahlia, ii, 201, 263.

Wildness of the progeny of crossed
tame animals, ii. 19, 20.

Wilkes, Caj)t., on the taming of pi-
geons among the Polynesians, ii. 144.

Wilkinson. J., on crossed cattle, ii. 82.

Williams, Mr., change of plumage in
a Hamburgh hen, i. 270.

494

WILLIAMS.

INDEX.

YOUATT.

Williams, Mr., intercrossing of straw-
berries, i. 374.

WiLLiAMSOJJ,Capt., degeneration of dogs
in India, i. 39 ; on small Indian asses,
i. 65.

Williamson, Rev. W., doubling of
Anemone coronaria by selection, ii.
184.

Willows, weeping, i. 385; reversion of
spiral-leaved weeping, i. 408 ; hy-
brids of, ii. 255; galls of, ii. 272,
273.

WiLLUGHBY, F., notice of spot pigeons,
i. 164; on a fantail pigeon, i. 218;
on tumbler pigeons, i. 219 ; on the
turbit, ibid. ; on the barb and carrier
pigeons, i. 221; on the hook-billed
duck, i. 291.

WiLMOT, Mr., on a crested white Turkey-
cock, 1. 309 ; reversion of sheep in
colour, ii. 3.

Wilson, B. 0., fertility of hybrids of
humped and ordinary cattle in Tas-
mania, i. 87.

Wilson, Dr., prepotency of the Manx
over the common cat, ii. 41.

Wilson, James, origin of dogs, i. 16.

Wilson, Mr., on prepotency of trans-
mission in sheep, ii. 45 ; on the
breeding of bulls, ii. 180.

Wings, proportionate length of, in dif-
ferent breeds of pigeons, i. 185, 186;
of fowls, eflects of disuse on, i. 284,
285 ; characters and variations of, in
ducks, i. 299-301 ; diminution of, in
birds of small islands, i. 301, 302.

Wing-feathers, number of, in pigeons,
i. 167 ; variability of, in fowls, i.
271.

Wolf, recent existence of, in Ireland, i.
16; barking of young, i. 27 ; hybrids
of, with the dog, i. 33,

WoLF-oOG, black, of Florida, i. 2?.

Wolves, North American, their resem-
blance to dogs of the same region, i.
21, 22 ; burrowing of, i. 27.

Woodbury, Mr., crossing of the Li-
gurian and common hive bees, i.
314, ii. 107; variability of bees, i.
314.

tVooDWARD, S. p., on Arctic Mollusca,
ii. 244.

Wood, Willoughby, reversion from a

cross, ii. 15; on Mr. Bates' cattle, ii.

96.
WoOLER, W. A., on the young of the

Himalayan rabbit, i. 114; persistency

of the coloured calyx in a crossed

polyanthus, i. 389.
WOU-VDS, healing of, ii. 284.
Wright, J., production of crippled

calves by shorthorned cattle, ii. 97;

on selection in cattle, ii. 178 ; effect

of close inter-breeding on pigs, ii.

101; deterioration of game-cocks by

close interbreeding, ii. 105.
Wright, Strethill, on the develo])-

ment of the hydroida, ii. 564.
Wyman, Dr., on Niata cattle, and on a

similar malformation in the codfish,

i. 93; on Virginian pigs, ii. 212;

browsing under water, ii. 294.

XenophoN, on the colours of huntiug

dogs, ii, 194.
XiMENES, Cardinal, regulations for the

selection of rams, ii. 188.

" Yaiiu," the name of the pigeon in
Persia, i. 163.

Yaks, domestication of, i. 86 ; selection
of white-tailed, ii. 190.

Yam, development of axillary bulbs in
the, ii. 153,

Yarrell, Mr., deficiency of teeth in
hairless dogs, i. 36, ii. 319 ; on ducks,
i. 294, ii. 250 ; characters of do-
mestic goose, resembling those of
Ans(r albifrons, i. 303 ; whiteness of
ganders, ibid- ; variations in gold-
fish, i. 312, 313 ; assumption of male
plumage by the hen-pheasant, ii. 26 ;
effect of castration upon the cock, ii.
26, 27 ; breeding of the skyl.trk in
j captivity, ii. 137 ; plumage of the
male linnet in confinement, ii. 141 ;
on the dingo, ii. 251.

Yellow fever, in Mexico, ii. 266.

Yew, tasrigate. ii. 228.

Yew, Irish, hardy in New York, ii.
299.

Yew, weeping, i. 385 ; propagation of,
by seed, i. 461.

YoLK, variations of, in the eggs of
ducks, i. 295.

Youatt, Mr., history of the dog, i. 17,

YOUATT.

INDEX.

ZOPF-TAUBE.

495

variations of the pulse ia breeds of
(logs, i. 37; liability to disease in
dogs, t'(u/. , ii. 213; inheritance of
goitre iu dogs, i. 455 ; on the gro}--
hound, i. 35, 43 ; on King Charles'
si)aniels, j. 43; on the setter, ibid.;
on bre'Hls of horses, i. 51 ; variation
iu the number of ribs in the horse, i.
52 ; inheritance of diseases in the
horse, i. 454, 455 ; introduction of
Eastern blood into English horses, ii.
197, 198 ; on white Welsh cattle, i.
89, ii. 193 ; improvement of British
breeds of cattle, i. 96 ; rudiments of
horns in young hornless cattle, ii. 30,
30(3; on crossed cattle, ii. 82, 98;
on Bakewell's long-horned cattle, ii.
i)'6 • selection of qualities in cattle, ii.
180; degeneration of cattle by neg-
lect, ii. 225; on the skull iu horn-
less cattle, ii. 326 ; disease of white
parts of catlle, ii. 331 ; displacement
of long-horned by short-horned cattle,
ii. 421; on Angola sheep, i. 98; on
the fleece of sheep, i. 103 ; correla-
tion of horns and fleece in sheep, i.
99 : adaptation of breeds of sheep to
climate and pasture, i. 100; horns of
Wallacliian sheep, i. 99; exotic
sheep in the Zoological Gardens, i.
100, ii. 296; occurrence of horns in
hornless breeds of sheep, ii. 3 ; on
the colour of sheep, ibid. ; on inter-
breeding sheep, ii. 98 ; on Merino

rams in Germany, ii. 180; effect of
unconscious selection on sheep, ii.
198; reversion of Leicester sheep on
the Lammermuir Hills, ii. 209 ; on
many-horned sheep, ii. 318; redac-
tion of bone in sheep, ii. 228 ; per-
sistency of character in breeds of
animals in mountainous countries,
ii. 39 ; on interbreeding, ii. 95 ; on
the power of selection, ii. 178, 179;
slowness of production of breeds, ii.
230; passages in the Bible relating
to the breeding of animals, ii. 186.

Young, J., on the Belgian rabbit, i. 110.

Yule, Capt., on a Burmese haii*y family,
ii. 53, 320.

Zambesi, striped young pigs on the, i.
80.

Zambos, character of the, ii. 21.

Zarco, J. G., introduction of rabbits
into Porto Santo by, i. 117.

Zea altissiina, i. 340 ; mays, i. 338.

Zebu, i. 82 ; domestication of the, i.
86 ; fertile crossing of, with. Euro-
pean cattle, i. 82, ii. 88.

Zebra, hybrids of, with the ass and
mare, ii. 16.

Zephyranthes Candida, ii. 147.

Zinnia, cultivation of, ii. 249.

Zollinger on Malayan penguin ducks,
i. 295.

Zoospore, division of, in Algae, ii. c72.

" Zopf-Taube," i. 161.

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Boul, includiUji sex, temperament, race, civilization, eic.'—Proviaeuce Pie^s.

PREHISTORIC TIMES, AS ILLUSTRATED BY ANCIENT

REMAINS AND THE MANNERS AND CUSTOMS OF MODERN

SAVAGES. Illustrated. Entirely new revised edition. 8vo. Cloth,

$5.00.

The book ranks amon^ the noblest works of the interesting and important
class to which it belo.ig^. As a resume of our preseut knowledge of prenistoric
man, it loves norhing; to bo desired. It is not only a good book of reference but
the best on the subject.

" This is. p'irhaps, the best auminary of evidence now In our possession con-
cerning^ the general charaoter of pieliistoric times, 'i he BroLze Aire, The Stone
Acre, The Tu.nuli, The Lake Inhatiitants of Switzerland, The Shell Mounds, The
Cave iian, and I'he Antiquity of Man, are the titles of tlie most important chap-
ters."—Z>r. (J. K. Adanis's Manual of Historical Literature.

ANTS, BEES, AND WASPS. A Record of Observations on the

Habits of the Social Hymeaoptera. With Colored Plates. 12ino.

Cloth, $2.00.

"This volume contains the record of various experiments made with ants,
bees, and wasp? durinir the last ten years, with a view to test their mental ccm-
dition and powers of sense. The principal point in which SirJohns mode of
es:periment differs from those of Huber. Forel, McCook, and others, is that he
has carefully watched and marked particular insects, and Las had iheir nests
under observa ion for l«>n<? periods— one of his ants' nests having been under
constant inspection ever since 1874. His observations are made principally upon
ants, because they show more power and flexibility of mind; and the value of
his studies is that they belong to the department of original research."

" We have no hesit/^tion In savine that the author has presented us with the
most valuable series of observations on a special subject that has ever been pro-
duce I, charmingly written, full of logical deductions, and, when we consider hi8
multitudmon-* eniragements. a remarkable illustration of economy of lime. As a
contribution to i'lsiftct nsjcholo^y, it will be long before this book finds a par*
oWiiV^—Jjindon Athenceum.

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

D. APPLETON & 00/S PUBLIOATIONS.

Professor JOSEPH LE CONTE'S WORKS.

SIGHT: AN EXPOSITION OF THE PRINCIPLES OF MONOCULAR

AND BINOCULAR VISION. With numerous Illustrations. 12mo.

Cloth, $1.50.

•'It is pleasant to find an American book which can rank with the very best
of foreign works on this subj.'ct. Professor Le Conte has loner been known as
an original investij^ator in this department ; all that he gives us is treated with
a master-hand. "—I'/ie Nation.

ELEMENTS OF GEOLOGY : A TEXT-BOOK FOR COLLEGES
AND FOR THE GENERAL READER. By Joseph Le Conte,
LL. D., Professor of Geology and Natural History in the University
of California. With upward of 900 Illustrations. New and enlarged
edition. 8vo. Cloth, $4.00.

A C03IPEND OF GEOLOGY ; APPLETONS' SCIENCE TEXT-
BOOK SERIES. 12 mo. Cloth, $1.40.

RELIGION AND SCIENCE: A SERIES OF SUNDAY LECT-
URES ON THE RELATION OF NATURAL AND REVEALED
RELIGION, OR THE TRUTHS REVEALED IN NATURE AND
SCRIPTURE. 12mo. Cloth, $1.50.

" Professor Le Conte 2:rapples with some of the irravpst questions which agitate
the thinking world. He treats of them all with dignity and fairness, and in a
manner so clear, persuasive, and eloquent, as to engage the undivided attention
of the reader. We commend the book cordially to the regard of all who are
interested in whatever pertains to the discussion of these grave questions, and
especially to those who desire to examine closely the strong foundations on
which the Christian faith is reared."— Sosto^i Journal.

"This volume is written with much clearness of thought and unusual clear-
ness of expression. It is partly a treatise on natural theology and partly a
defense of the Bible against the assaults of modern science. In the later aspect
the author's method is an eminently wise one. He accepts whatever science has
proved, and he also accepts the divine origin of the Bible. Where the two seem
to conflict, he prefers to await the reconciliation, which is inevitable if both are
true, rather than to waste time and words in inventing ingenious and doubtful
theories to force them into seeming accord. Both as a theologian and a man of
science, Professor Le Conte's opinions are entitled to respectful attention, and
there are few who will not recognize his book as a thoughtful and valuable con-
tribution to the best religious literature of the day."— iVez^ York World.

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

D, APPLETON & OO.'S PUBLICATIONS.

GEORGE J. ROMANES'S WORKS.

JELLY-FISH, STAR-FISH, AND SEA-URCHINS. Being
a Research on Primitive Nervous Systems. 12mo. Cloth, $1.75.

" Althon<::h I have throui^hont kept in view the requirements of a general
reader, I nave also eouiiht to render the book of service to the workiiiir phyti-
ologist, by bringing together in one consecutive account all the more important
observ.itions and results which have been yielded by this research." — Extract
from P> eface.

"A profound research into the laws of primitive nervous systems conducted
by one of the ablest linglish investigators. Mr. Komanes set up a tent on the
beach and examined his beautiful pets lor six summers in succession, t-uch
patient and loving work has borne its fruits in a mcsnograph winch leaves
nothing to be said about jslly-Qsh, t tar-fish, and sea-urchins. Every one who
has stuliied the lowest forms of lit\; on the sea-shore admires these objects. But
few have any idea of the exquisite delicacy of their structure and their nice
adaptation to their place in nature. Mr. Komanes brings out the suotile beauties
of t.ie ruaimenrary organisms, and shows tiie resi-mblances tiiey bear to ttie
higher types of creation. His explanations are made more clear by a large
number of illustrations. While the book is well adapred lor ; opuiar reading it
is of special value to working physiologists. "'—iV'e?^ lork Journal oj Commerce.

" A most admirable treatise on primitive nervous systems. The subject-matter
is full of original investigations and experiments upon the animals mentioned aa
types of the lowest nervous developments."— jBcston Commercial Bulletin.

"Mr. Georire J. Romanes has already established a reputation as an exact and
comprehensive naturalist, which ids later work. ' Jelly-i'ish, Star-Fish, and Sea-
Urchius,' fully confirms. These marine animals are well known upon our coasts,
and always interest the on-lookers. In this volume (one of the 'luternational
Scientific series ') we have the whole story of their toimation, existence, nervous
system, etc., made most interesting by the simple and non-professional manner
of treating the subject. Ihustrations aid the text, and the proiessional student,
the naturalist, all lovers of the rocss, woods, and shore, as well as the general
reader, will find instruction as well as delight in the narrative."— £o6fon Com-
monwealth.

ANIMAL INTELLIGENCE. 12mo. Cloth, $1.75.

"A collection of facts which, though It may merely amuse the unscientific
reader, will be a real boon to the student of comparative psychology, for this is
the first attempt to present systematically the well-assured results of observation
on the mental life of animals." — Saturday Review.

MENTAL EVOLUTION IN ANIMALS. With a Posthumous
Essay on Instinct, by Charles Darwin. 12mo. Cloth, $2.00.

"Mr. Romanes has followed up his careful enumeration of the facts of * Ani-
mal Inteliigence,' contributed to the ' International Scientific Series,' witli a
work dealini,' with ilie successive stages at which the vaiions mental phenomena
app iar in the scale of life. The present installment displays the same evidence
of industry m coUectini; facts and caution in co-ordinating them by theory as the
lormer."— TVie Athenceum.

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

D. APPLETON & CO/S PUBLICATIONS,

DR. HENRY MAUDSLEY'S WORKS.

BODY AND WILL : Being an Essay concerning AVill in its
Metaphysical, Physiological, and Pathological Aspects. 12mo.
Cloth, $2.50.

BODY AND MIND : An Inquiry into their Connection and Mutual
Influence, specially in reference to Mental Disorders. 1 vol., 12mo.
Cloth, ^1.50.

PIirSIOLOGY AND PATHOLOGY OF MIND:

PHYSIOLOGY OF THE MIND. New edition. 1 vol., 12mo.
Cloth, $2.00. Contents : Chapter I. On the Method of the Study
of the Jlind.— II. The Mind and the Nervous System.— III. The
Spinal Cord, or Tertiary Nervous Centres ; or. Nervous Centres
of Keflex Action. — IV. Secondary Nervous Centres ; or, Sensory
Ganalia; Sensorium Commune. — V. Hemispherical Ganglia; Cortical
Cells of the Cerebral Hemispheres; Ideational Nervous Centres;
Primary Nervous Centres ; Intellectoi ium Commune. — VI. The
Emotions. — VII. Volition. — VIII. Motor Nervous Centres, or Mo-
torium Cummune and Actuation or EfLCCticn. — IX. Memory and
Imagination.

PATHOLOGY OF THE MIND. Being the Third Edition of
the Second Part of the " Physiology and Pathology of Mind,"
recast, enlarged, and rewritten. 1 vol., 12mo. Cloth, $;2.00. Con-
TKNTS: Chapter I. Sleep and Dreaming. — H. Hypnotism, Somnam-
bulism, and Allied States. — III. The Causation and Prevention of
Insanity : (A) Etiological. — IV. The same continued. — V. The
Causation and Prevention of Insanity: (B) Pathological. — VI. The
Insanity of Early Life. — VII. The Symptomatology of Insanity. —
VIII. The same continued. — IX. Clinical Groups of Mental Disease.
— X. The Morbid Anatomy of Mental Derangement. — XI. The
Treatment of Mental Disorders.

RESPONSIBILITY IN MENTAL DISEASE. (International
Scientific Series.) 1 vol., 12mo. Cloth, $1.50.

" The author ip at home in his pubject, and presents his views in an nlmrst
singularly clear and satisfactory manner. . . . The volrme is a vaUiaMe contri-
bution to one of the most difficult and at the same time one of the most impor-
tant subjects of investieration at the present day." — New York Observe?'.

'* Handles the imnortant to))ic with masterly power, and its suggestionB are
practical and of great ya\ue.^''— Providence Press.

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

D. APPLETON & CO/S PUBLICATIONS.

DISCUSSIONS ON CLOIATE AND COSMOLOGY. By

James Ckoll, LL. D., F. R. S. With Chart. 12mo. Cloth, 82.00.

Contents : Misapprehensions regardino^ the Physical Theory of Secular
C langes of Climate.— Tue Ice ot Greeuland and the Antarctic ('ominent not due
to Elevation of tiie Land. — Mr. Alfred &. Wallace's Modification of the Physical
Theory of Secular Chanties of Climate — The Physical Cause of Mild Pciar Cli-
mites — Intercrlacial Periods and Distribution of Flora and Fauna in Arctic
Regions. — Temperature of Space and its Bearing on Terrestrial Physics. — Prob-
able Origin and' Age of the Suu's Heat, etc., etc.

CLIMATE AND TIME IN THEIR GEOLOGICAL RE-
LATIONS: A THEORY OF SECULAR CHANGES OF THE
EARTH'S CLIMATE. By James Ceoll, of H. M. Geological Survey
of Scotland. With Maps and Illustrations. 12mo. Cloth, $2.50.

"I have studiously avoided introducing anything of a hypothetical character.
All the conclusions are based on known tacts or af'.mitted physical priucinlcs.
In short, the aim of the work is to prove that secular chanees of climate follow,
as a necessary effect, from aimitted phy.^ical agencies, and that these changes,
in as far as the past climatic condition of the globe is concerned, fully meet the
demand of the geologist."— i'^rom the Preface.

OTHER WORLDS THAN OURS: THE PLURALITY OF
WORLDS, STUDIED UNDER THE LIGHT OF RECENT SCI-
EXTIFIC RESEARCHES. By Richard Anthony Proctor. With
Illustrations, some colored. 12mo. Cloth, $2.50.

LIGHT SCIENCE FOR LEISURE HOURS. A Series of
Familiar Essays on Scientific Subjects, Natural Phenomena, etc. By
Richard Anthony Proctor. 12mo. Cloth, $LY5.

THE MOON: HER MOTIONS, ASPECT, SCENERY, AND PHYS-
ICAL CONDITIONS. With Three Lunar Photographs, and many
Plates, Charts, etc. By Richard Anthony Proctor. 8vo. Cloth,
$3.50.

THE EXPANSE OF HEAVEN. A Series of Essays on the

Wonders of the Firmament. By Richard Anthony Proctor.
12mo. Cloth, $2.00.

OUR PLACE AMONG INFINITIES. A Series of Essays con-
trasting our Little Abode in Space and Time with the Infinities
around us. To which arc added Essays on the Jewish Sabbath and
Astrology. By Richard Anthony Proctor. 12mo. Cloth, $1.75.

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

D. APPLE TON & CO/S PUBLICATIONS.

THE GEOGRAPHICAL AND GEOLOGICAL DISTRI-
BUTION OF ANIMALS. By Angelo Heilprin, Professor
of Invertebrate Paleontology at the Academy of Isatural Sciences,
Philadelphia, etc. 12mo. $2.00.

" An important contrihation to physical science is Angelo Heilprin's 'Geo-
grapliical and Geological Distribuliou of Animals.'' The author has aimed to
present to hi> readers such of the more significant facts connected with the past
and pre-eni distribation of animal life as might lead to a proper concejdiou of
the relations of existinir fauna, and also to luriiisii the s-ludent with a work of
goaeral reference, wherein the more i=alient features of the geography and geolo-
gy ot animal forms could be readily ascertained. While iliis book is arldressed
chiefly to the naturalist, it contains much information, particularly on ihe sub-
ject of the geo^rapiiical distribution of animals, the rapioly increasing growih of
some species and the gradual extinction of otherf', whith will interest and in-
struct th;i general reader. Mr. Heilprin is no believer in the doctrine of inde-
pcsiident creation, but ho'ds that animate nature must be looked upon as a con-
crete whole."— A^eu* Yoric Sun.

MICROBES, FERMENTS, AND MOULDS. By E. L. Troues-
SARf. With 107 Illustrations. 12mo. Cloth, $1.50.

"Microbes are everywhere ; every species of plant hap its special parasite?,
the vine having more than one luindrerl foes oi this kind. Fungi of a nucrcccopic
size, they have their uses in nature, since they clear the surface of the earth Irom
dead bodies and fecal matter, fioin all dead and useless substances which are the
refus3 of life, and return to the soil the >oluble mineral substances fr< m which
plants are derived. AH fermented liquors, wine, beer. vine<.ar, etc., are artificially-
produced by the species of microbes called ferments; they also cause bread to
rise. Others are injurious to us, for in the shape of spores and seeds they enter
our bodies witli air and water and caut^e a large nunber ot the diseases to whi( h
the flosh is hsir. Many physicians do not accept the niicrob.an theory, consider-
ing that when microbes are tound in the blood they are neither the cause of the
disease, nor the contagious element, nor iho vehicle of contagion. In France the
opponents of the microhian theory are Robin. Hechamp. and Jcusset deBellesme;
in England, Lewis and Lionel Beale. The writer <omes to the conclusi(>n that
Pasteur's microhian theory is the only one that explains all facts,"— Aee^ 1'oik
TimcS.

EARTHQUAKE! AND OTHER EARTH MOVEMENTS.

By John Milne, Professor of ilining and Geology in the Imperial
College of Engineering, Tokio, Japan. With 38 Illustrations. 12mo.
Cloth, .$1.75.

"In this little book Trofessor Milne has endeavored to bring together all that
is known concernins the nature and causes of earthquake mcvercents. His task
wag one of much difficu.ty. Professor Milne's excellent work in the science of
seismology has been done in Japan, in a region of incessant shocks of suflficient
energy to nake observation possible, yet, with rare exceptions, of no disastrous
effects. He has haa the good fortune to be aided by Mr, Thomas Gray, a gentle-
man of great con?tructive skill, as well as by Professors J. A. Ewing, W. S. Chap-
lin, and his other colleairnes in the scientific colony which has fathered ahoit the
Imperial University of J;)pan. To these lentlemen we owe the best of our sci-
ence of seismology, for b-fore their achievements we had nothing of value oon-
ceniing the physical conditions of earthquakes except the croat works o' Kcbeit
Mallet; an i Mallet, with all his renins and devotion to the subject, I ad b' t lew
chanci^s to observe the actual shocks, and so failed to understai:d many of their
important features."— :/'Ae Nation.

New York : D. APPLETON & CO., 1, 3, & 6 Bond Street.