(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "The variation of animals and plants under domestication"

1 Wahtij& Si 


^0^^|Sk 




^;^^«j^raiL^ 










%M 









' A ft • 



^^^fV^^P?'' • 



f*vt#M- 






i*ji 



A- :^v 

ML* .":•- 



«•>* 



.Hfc* 



RsS 



<*• 



Mi* 









90. * • 



¥M& 



^■w-m 



THE VAEIATION 



ANIMALS AND PLANTS 



tTNDER 



DOMESTICATION. 



By CHAELES DARWIN, M.A., F.E.S., &o. 



SECOND EDITION, BE VISED. FOURTH THOUSAND. 



IN TWO VOLUMES.— VOL. II. 

WITH ILLUSTRATIONS. 

:eau of 

AMERICAN ETHNOLOGY, I 

6020 

1SQQ 

LIB RARY 

NEW YOEK: 
D. APPLETON AND COMPANY, 

1, 3, and 5 BOND STREET. 
1894. 



CONTENTS. 



CHAPTEE XIII. 

INHERITANCE, continued — REVERSION OR ATAVISM. 

DIFFERENT FORMS OF REVERSIOX — IX PURE OR UNCROSSED BREEDS, AS 
LN PIGEONS, FOWLS, HORXLESS CATTLE AND SHEEP, IX CULTIVATED 
PLAXTS — REVERSIOX IX FERAL AXIMALS AXD PLAXTS — REVERSIOX 
LX CROSSED VARIETIES AXD SPECIES — REVERSION THROUGH BUD- 
PROPAGATIOX, AXD BY SEGMENTS IX THE SAME FLOWER OR FRUIT 
— IX DLFFEREXT PARTS OF THE BODY IX THE SAME ANIMAL— 
THE ACT OF CROSSIXG 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 ADVAXCIXG AGE OF CHARACTERS DERIVED 
FROM A CROSS — THE GERM, WITH ALL ITS LATEXT CHARACTERS, 
A WOXDERFUL OBJECT — MOXSTROSITIES — PELORIC FLOWERS DUE IN 

some cases to reversiox Pacres 1-36 



CHAPTER XIV. 

inheritance, continued — FIXEDNESS of CHARACTER — 
PKEPOTENCT — SEXUAL LIMITATION — CORRES PON DENCE 
OF AGE. 

FIXEDNESS 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 LATEXT IX THE OTHER — IXHERITAXCE AS LIMITED BY SEX — 



IV CONTENTS. 

NEWLY-ACQUTRED 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 EMBRY- 
OLOGY ; AS EXHIBITED LN 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. 

OX CROSSING. 

FREE INTERCROSSING OBLITERATES THE DIFFERENCES BETWEEN ALLIED 
BREEDS — WHEN THE NUM3ERS 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 LN 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 LN RELATION TO THE FORMATION OF 
DOMESTIC RACES 62-77 



CHAPTER XYI. 

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

DLFFICULTLES IN JUDGING OF THE FERTILITY OF VARIETIES WHEN 
CROSSED — VARIOUS CAUSES WHICH EEEP 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 

KENDERED 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 CROSSING, AND ON THE EVIL 
EFFECTS OF CLOSE INTERBREEDING. 

DEFINITION OF CLOSE INTERBREEDING — AUGMENTATION OF MORBID 

TENDENCIES GENERAL EVIDENCE OF THE GOOD EFFECTS DERIVED 

FROM CROSSING, AND ON THE EVIL EFFECTS OF CLOSE INTERBREED- 
ING — CATTLE, CLOSELY INTERBRED J 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 SLZE 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 



CHAPTEE 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 FRF IT — 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 THE FOUR LAST CHAPTERS, "WITH REMARKS 
ON HYBRIDISM. 

ON THE EFFECTS OF CROSSLNG 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- 
TION — INFLUENCE OF DIFFERENT BREEDERS ON THE SAME SUB- 



CONTESTS. Vll 

VARIETY — PLANTS AS AFFECTED BY UNCONSCIOUS SELECTION — 
EFFECTS OF SELECTION AS SHOWN BY THE GREAT AMOUNT OF 
DIFFERENCE IN THE PARTS MOST VALUED BY MAN .. Pages 176-208 



CHAPTER XXI. 

selection, continued. 

STATURAL 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. 

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, 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 



Vlll CONTENTS. 

CAUSE VARIABILITY — CROSSING 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 Pa2;cs 237-259 



CHAPTER XXIII. 

DIRECT AND DEFINITE ACTION OF THE EXTERNAL CON- 
DITIONS OF LIFE. 

FLIGHT MODIFICATIONS IN PLANTS FROM THE DEFINITE ACTION OF 
CHANGED CONDITIONS, IN SFZE, COLOUR, CHEMICAL PROPERTIES, 
AND IN THE STATE OF THE TISSUES — LOCAL DISEASES CON- 
SPICUOUS MODIFICATIONS FROM CHANGED CLIMATE OR FOOD, ETC. 
— PLUMAGE OF BLRDS 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 PLAXTS — VARIOUS METHODS BY WHICH THIS CAN 
BE EFFECTED — ARRESTS OF DEVELOPMEXT— RUDIMEXTARY ORGANS. 

283-310 



CONTENTS. IX 



CHAPTER XXV. 

LAWS OF VARIATION, continued — COEEELATED VAEIA- 
BILITY. 

EXPLANATION OF TEEM 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 
GROWTH COMPLICATED BY THE ACCUMULATED EFFECTS OF NATURAL 
SELECTION — COLOUR AS CORRELATED WITH CONSTITUTIONAL PECU- 
LIARITIES Pao;es 31 1-332 



CHAPTER XXVI. 

LAWS OF VAEIATION, 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 .. .. Pases 349-3y9 



CHAPTER XXYIH. 

CONCLUDING REMAKES. 

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 



LNDEX 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 LN CROSSED 

VARLETLES AND SPECIES REVERSION THROUGH BUD-PROPAGATION, AND 

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

The great principle of inheritance to be discussed in this 
chapter has been 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 
Reversion, or Throwing-back ; by the French Pas-en-Arriere ; 
and by the German Buckschlag, or BiickscJiritt. 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 a]l 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 IXHEEITAXCE. Chap. XIII. 

character, and the 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 cause may be, inherit 
the character in question, but resembles its grandparents, Ave 
have one of the simplest cases of reversion. We continually 
see 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 may be divided into two main classes 
which, however, in some instances, blend into one another; 
namely, first, those occurring in a variety or race which has 
not been crossed, but has lost by variation some character 
that it formerly possessed, and which afterwards reappears. 
The second class includes all cases in which an individual 
with some distinguishable character, a race, or species, has at 
some former period been crossed, and a character derived from 
this cross, after having disappeared during one or several 
generations, suddenly reappears. A third class, differing only 
in the manner of reproduction, might be formed to include 
all cases of reversion effected by means of buds, and therefore 
independent of true or seminal generation. Perhaps even a 
fourth class might be 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. 

Recersion to lost Characters by pure 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 bluebirds with all 
the marks characteristic of the wild Columba lima. Similar 



Chap. XIII. REVERSION. 6 

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

The aboriginal species from which our domesticated cattle 
and sheep are descended, no doubt possessed horns ; but 
several hornless breeds are now well established. Yet in 
these — for instance, in Southdown sheep — " it is not unusual 
to find among the male lambs some with small 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 off." 1 The 
Galloways and Suffolk cattle have been hornless for the last 
100 or 150 years, but a horned calf, with the horn often 
loosely attached, is occasionally produced. 2 

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. 3 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, during 
the last century, the Leicester sheep have been bred with the 
most scrupulous care ; yet occasionally grey-faced, or black- 
spotted, or wholly black lambs appear. 4 This occurs still 
more frequently with the less improved breeds, such as the 
Xorfolks. 5 As bearing on this tendency in sheep to revert 
to dark colours, I may state (though in doing so I trench on 

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

The same fact of loose horns oc- 4 I have been informed of this fact 

casionally appearing in hornless bree is through the Ilev. W. D. Fox, on the 

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

Bechstein, ' iS T aturge.ich. Deutsch- see, also, remarks on this subject in 

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

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

3 Youatt on Sheep, 1838, pp. 17, 5 Youatt, pp. 19, 234. 



4 INHERITANCE. Chap. XIH. 

the reversion of crossed breeds, and likewise on the subject of 
prepotency; that the Rev. W. D. Fox was informed that seven 
white Southdown ewes were put to a so-called Spanish ram, 
which had two small black spots on his sides, and they 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. Mr. Fox was 
also told by the friend from whom the spotted breed was 
procured, that he likewise had gone on for six or seven 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 6 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 ;" 7 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 

6 ' The Poultry Book,' by Mr. much experience on this subject, has 
Tegetmeier, 1866, p. 231. likewise assured me that this some- 

7 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 remarked, 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 8 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 tlieir conditions of life, to a wild or 
nearly wild condition : Mr. Buckman has effected this with 
the parsnip ; 9 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 ichich 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. Many 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. 10 In several cases we do not 
know the aboriginal parent-species, and cannot possibly tell 

8 ' Gardener's Chron.,' 1855, p. found that they are not able to es- 
777. tablish themselves; they generally 

9 Ibid., 1862. p. 721. perish from the frozen snow clinging 

10 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 running wild in the slopes. On one occasion two ewes 
Bavarian Alps ; but, on making survived the winter, but their lambs 
farther inquiries at my request, he perished. 



6 INHERITANCE. Chap. XIII 

whether 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 always be exposed to new conditions of life, 
for. as Mr. Wallace u has well remarked, they have to obtain 
their own food, and are exposed to competition with the native 
productions. Under these circumstances, if onr dumesticated 
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 tins 
tendency has been much exaggerated by some authors. 

I will briefly run through the recorded cases. With neither 
horses nor cattle is the primitive stock known; and it has been 
shown in former chapters that they have assumed different colours 
in different 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 unusually 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 the West Indies, 
South America, and the Falkland Islands, and have everywhere 



11 See some excellent remarks on Proc. Lmn. Soc., ? 1858, vol. iii. p. GU 
this subject by Mr. Wallace, •Journal 



Chat. XIII. EE VERSION. 7 

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 different parts of South America as differing in several 
respects. In Louisiana the pig 12 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, 13 it is not known what variety was first turned out, nor 
what 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 14 has strongly 
insisted on what slight evidence the common belief in theii 
reversion to a primitive state rests. Godron 15 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. 

Reversion 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 mu>t 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- 

12 Dureau de la Malle, in ' Comptes appear to me worth copying; but I now 
Rendus,' torn, xli., 1835, p. 807. find that Dureau de la Malle (' Comp- 
From the statements above given, the tes Rendus,' torn, xli., 1855, p. 690) 
author concludes that the wild pigs advances this as a good instance of 
of Louisiana are not descended from reversion to the primitive stock, and as 
the European Sus scrofa. confirmatory of a still more vague 

13 Capt. W. Allen, in his ' Expe- statement in classical times by Varro. 
dit-'on to the Niger,' states that fowls 14 ' Flora of Australia,' 1859, In- 
have run wild on the island of Anno- troduct., p. ix. 

bon, and have become modified in 15 ' De l'Espece,' torn. ii. pp. 54, 

form and voice. The account is so 58, 60. 
meagre and vague that it did not 



8 INHERITANCE. Chap. XIII. 

sion, one of their grandparents, or some more distant collateral 
relation. Very many anomalies of structure and diseases, 16 
of which 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, he 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. R. 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 very 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 plants. Mr. Sidney 1T 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 

16 Mr. Sedgwick gives many in- July. 1863, pp. 448, 188. 
stances in the ; British and Foreign 1: In his edit, of ' Youatt on the 

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



Chap. XIII. EEYEESION. V 

before in giving size and constitution to the breed. I ob- 
served 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 
Mai ays ; 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 
rise 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. No 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 
lengths. 18 But neither in the case of a breed which has been 
contaminated by a single cross, nor when, 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 parent-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 clay, has 
insisted on this tendency. Gartner has recorded some good 
instances; but no one has given more striking ones than 

18 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 they would be superfluous. 



10 INHERITANCE. Chai\ XII [. 

Naudin. 19 The tendency differs 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 tho 
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." 20 

lit version through Bud-propagation — Partial Reversion, by seg- 
ments in the same flower 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 

19 Kolreuter gives curious cases in ' Med.-Chirurg. Review,' April, 1861, 
his * Dritte Fortsetznng/ 1766, ss. 53, p. 485. Dr. H. Dobell, in 'Med.- 
59; and in his well-known ' Memoirs Chirurg. Transactions, 1 vol. xlvi., 
on Lavatera and Jalapa.' Gartner,. gives an analogous ca-e, in which, in 
' Bastarderzeugung,' ss. 4-37, 441, &c. a large family, ringers with thickened 
Naudin, in nis " Recherches sur joints were transmitted to several 
rHybridite," * Nonvelles Archives du members during five generations; 
Museum,' torn. i. p. 25. but when the blemish once disappeared 

20 Quoted by Mr. Sedgwick in it never reappear.' I. 



Chap. XIII. EEVERSION. 11 

by segments. Yilmorin 21 lias 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 occasional^ 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 22 insists in his discussion on disjunction of character, 
are closely analogous with those given in the eleventh chapter, 
in which crossed plants have been known to produce half- 
and-half or striped flowers and fruit, or distinct kinds of 
flowers 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 with advancing age revert wholly or by seg- 
ments to either parent-form, or to both. Thus, young trees 
of the Gytisus 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 Tropaeolum, 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 word ; never- 
theless, as the change is effected through a succession of bud- 
generations on the same plant, they may be thus included. 

Analogous facts have been observed in the animal kingdom, 

21 Verlot, ' Des Variete's,' 1865, torn. i. p. 25. Alex. Braun (in his ' Re- 
p. 63. juvenescence,' RaySoc, 1853, p. 315) 

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



12 INHERITANCE. Chap. XIIL 

and are more remarkable, as they occur in tlie 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 23 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 offspring 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, 24 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. \\ 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 24 Quoted by Hofacker, * Ueber di« 

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



Chap. XIII. REVERSION. 13 

generations ; but characters sometimes reappear in the 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. 25 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." 26 
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. 27 Now as Gallus bankiva 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 

25 Azara, « Essais Hist. Nat. de 'The Poultry Book,' by Mr. Teget- 

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

28 These facts are given on the 27 ' The Poultry Book,' by Teget- 

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

23 



14 INHERITANCE. Chap. XIII. 

conclusion seems to me highly 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 MM. Boitard and Corbie having 
stated that, when they crossed certain breeds of pigeons, birds 
coloured like the wild C. livia, or the common dovecot — namely, 
slaty-blue, with double black wing-bars, sometimes chequered. 
with black, white loins, the tail barred with black, with the outer 
feathers edged with white, — 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, young birds were often produced, more or less 
plainly coloured slaty-blue, with some or all of the proper 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 reel-spot, white fantail, and 
two black barbs, from any of which, when purely-bred, the produc- 
tion of a pigeon coloured like the wild (.'. livia 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 Gattus bankiva. 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 inauy gallinaceous birds, is likewise apparently a 
ca^e 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 GaUus varius; and these feathers are transversely 
striped in a conspicuous manner with dark metallic blue and grey, 
a character which 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 liko 
the mallard (J., boschas). 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 white drake to a slate-coloured duck. 



Chap. XIII. KE VERSION. ID 

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 period 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, 28 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 29 that cross-bred animals between two kinds, both 
of which are good milkers, such as Alclerneys 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 



28 'Gardener's Chron. and Agri- of cattle as Mr. Willoughby Wood 
cultural Gazette,' 1866, p. 528. (' Gard. Chron.' 1869, p. 1216), admits 

29 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. Chat. XIII 

kinds of dims. 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 j>rove that striped d uns 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 Eguus txniopus of Abyssinia, 30 
which is generally thus striped. In the domestic animal the stripes 
on the shoulder are occasionally 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 was 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, 31 and remarks that mules are particu- 
larly liable to be thus striped on their legs. In South America, 
according to Eoulin, 32 such stripes are more frequent and con- 
spicuous in the mule than in the ass. In the United States, Mr. 
Gosse, 33 speaking 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 plainer 
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 striped ; 
but it appears from the figures given in Dr. Gray's 'Xnowsley 
Gleanings/ and still more plainly from that given by Geoffrey and 
F. Cnvier, 34 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.,' 1S35, p. 338. 

1 862, p. 163. 33 ' Letters from Alabama,' 1859, p. 

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

32 'Mem. presented par divers 34 'Hist. Nat. des Maramiferes. 
Savans a l'Aead. Royale,' torn. vi. 1820, torn. i. 



Chap. XIII. KE VERSION. 17 

that the ass aids in giving, 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. But 
in the famous hybrid bred by Lord Morton, 35 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 
horse, and bore two colts, both of which, as formerly stated, were 
plainly striped on the legs, and one of them likewise had stripes on 
the neck and body. 

The Equus indicus 36 is characterised by a spinal stripe, without 
shoulder or leg stripes ; but traces of these latter stripes may occa- 
sionally be seen even in the adult; 37 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 38 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 hypothetical^ 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 }3igeons 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, 
face, and probably over the whole body, like a zebra. 

Lastly, Professor Jaeger has given 39 a good case with pigs. He 



35 ' Philosoph. Transact.,' 1821, p. these, as with the horse and ass, are 

20. sometimes double : see Mr. Blyth, in 

33 Sclater, in ' Proc. Zoolog. S,e.,' the paper just quoted, and in 'Indian 

1862, p. 163: this species L the Sporting Review,' 1856, p. 320 : and 

Ghor-Khur of N.W. India, and has Col. Hamilton Smith, in 'Nat. Library, 

often been called the Hemionus of Horses,' p. 318; and 'Diet. Class. 

Pallas. See, also, Mr. Blyth's ex- d'Hist. Nat.,' torn. iii. p. 563. 
cellent paper in ' Journal of Ashttic 3S Figured in the ' Gleanings from 

Soc. of Bengal,' vol. xxviii., 1860, p. the Knowsley Menageries,' by Dr. J. 

229. E. Gray. 

37 Another species of wild ass, the 39 ' Darwin'sche Theorie und ihre 

true E. hemionus or Kiang, which Stellung zu Moral und Religion,' jt, 

ordinari\y has no shoulder-stripes, is 85. 
said occasionally to have them ; and 



18 INHERITANCE. Chap. XIII 

crossed the 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 thus 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 
are some breeds of fowls which are called " everlasting 
layers," 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. 40 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. Now, 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." 4l 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 

40 Cases of both Spanish and Polish from a cross between Golden and 
hens sitting are given in the ' Poultry Black Polish fowls, are "good and 
Chronicle,' 1855, vol. iii. p. 477. steady birds to sit." Mr. B. P. Brent 

41 ; The Poultry Book,' by Mr. informs me that he raised some good 
Tesretmeier, 1866, pp. 119, 163. The sitting hens by crossing Pencilled 
author, who remarks on the two Hamburg and Polish breeds. A 
negatives ('Journ. of Hort.,' 1862, cross-bred bird from a Spanish non- 
p. 325), states that two broods were incubating cock and Cochin incu- 
raised from a Spanish cock and Silver- bating hen is mentioned in the ' Poultry 
pencilled Hamburg hen, neither of Chronicle,' vol. iii. p. 13, as an "ex- 
which are incubators, and no less emplary mother." On the other 
than seven out of eight hens in these hand, an exceptional case is given in 
two broods "showed a perfect ob- the 'Cottage Gardener.' I860, p. 388, 
stinaoy in sitting." The Piev. E. S. of a hen raised from a Spanish cock 
Dixon C Ornamental Poultry,' 1848, and black Polish hen which did not 
p. 200) says that chickens reared incubate. 



Chap. XIII, KE VERSION. 19 

between two non-sitting breeds invariably recover their lost 
instinct, any more than that crossed fowls or pigeons invari- 
ably recover the red or bine 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 Gallus banhiva is sometimes reacquired both 
by 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 asked, 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 offspring 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 ;" 42 but I have 
myself seen one exception to this rule. Mr. S. J. Salter, 43 

« 'The Poultry Book,' by Teget- 43 ' Natural History Review,' 1863, 

meier, 1866, pp. 165, 167. April, p. 277. 



20 INHERITANCE. Chap. XIII. 

who raised a large number of hybrids from a bantarn-heii by 
Galbis sonneratii, states that ' : all were exceedingly wild." 
Mr. TVaterton 44 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 obstinac}" 
and vice. Mr. Brent, who has crossed canary-birds with 
many kinds of finches, has not observed, 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 45 observed that his hybrids were 
wild, and exhibited " migratory propensities" of which there 
is not a vestige in the common or musk duck. No 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 iu districts where large lakes and fens abound. Never- 
theless, a large number of cases have been recorded 46 of 
hybrids from these two ducks having been shot in a com- 
pletely wild state, although so few are reared in comparison 
with pur ely-bred birds of either species. It is improbable 
that any of these hybrids could have acquired their wildness 

44 ' Essays on Natural History,' p. asserts (' Zoologist,' vol. v., 1845-4H, 
917. p. 1254) that -everal have been shot 

45 As stated by Mr. Orton. in his in varinus parts of Belgium and 
' Phvsi"lugy vf Breeding.' p. 12. Northern France. Audubon (' Ornith- 

4i M. E. de Selys-Longchamps ol<>g. Biography,' voL iii. p. 168), 

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 oft and become <|uiU 

Switzerland and France. M. Deby will." 



Chap. XIII. REVERSION. 21 

from the musk-duck having paired with a truly wild duck ; 
and 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, many years ago, long before 
I had thought of the present subject, I was struck with 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. 47 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." 48 "When two races, both low in the scale, are crossed 
the progeny seems to be eminently 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. 49 
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 the proximate causes leading to Reversion. — When 

47 'Journal of Researches,' 1845, 49 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 reassnme long-lost characters, — 
when the common ass, for instance, is born with striped legs, 
when a pure race of black or white pigeons throws a slaty- 
bine 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 young 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 apparently 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 formerly shown, the transmission of 
the character pi oper to the variety, 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 pigeons, of well-established breeds, 
are united, the offspring are almost sure to inherit the same 
colours ; but when differently- coloured birds 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. EEVEKSION. 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 general 
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 hybrids and mongrels include 
all the characters of both parents, not fused together, but 
merely mingled in different proportions in different parts of 
the body ; or, as Naudin 50 has expressed it, a hybrid is a 
living mosaic- work, in which the eye cannot distinguish the 
discordant elements, so completely are they intermingled. 
We 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 which 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* 

50 'Nouvolles Archives du Museum/ torn. i. p. 151. 



24 INHERITANCE. Chap. XIII 

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

But Kaudin'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, namely, 
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 may perhaps be accounted for by the nature 
of the genera crossed by him, for he admits that the tendency 
differs in different genera. The statement is also directly con- 
tradicted by Xaudin's observations, and by the notorious fact 
that perfectly fertile mongrels exhibit the tendency in a high 
degree, — even in a higher degree, according to Gartner 
himself, than hybrids. 51 

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 TVichura, 52 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 sufficiently protected 
his hybrids from the pollen of the parent-species : Kaudin, on 
the other hand, who chiefly experimented on cucurbitaceous and 
other cultivated plants, insists more strenuously than any other 

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

51 ' Die Bastardbefruchtung . . . erzeugung, 5 s. 474. 582. 



Chap. XIII. REVERSION. 25 

author on the 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. 53 

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 aloue 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 remote 
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 

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

curious essay on the different 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- even to much shaking, gives a 

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



26 INHERITANCE. Chap. XIII. 

characters lying latent. The most obvious illustration is 
afforded by secondary sexual characters. In every female all 
the secondary male characters, 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 species. In 
the case of the hen-pheasant this has been observed to occur 
far more frequently during certain years than during others. 54 
A duck ten years old has been known to assume both the 
perfect winter and summer plumage of the drake. 55 Water- 
ton 56 gives a curious case of a hen which had ceased laying, 
and had assumed the plumage, voice, spurs, and warlike 
disposition of the cock ; when opposed to an enemy she would 
erect her hackles and show fight. Thus every 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 
Lob • when they are subjected to castration. Thus, if the 
operation be performed on a young cock, he never, as Yarrell 
. 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 affects the 
reproductive system, causing analogous results. But cha- 

54 Yarrell, 'Phil. Transact.,' 1827, Isidore Geoffroy Saiot-Hilaire. in his 

J; Dr. Hamilton, in ' Proc. ' Essais de Zoolog. Gen.' ('suites a. 

I - ..' 1862, p. . Button,' 1842, pp. 496-513), has 

55 • Archiv. Skand. Beit rage zur collected such cases in ten different 
Naturgesch.' viii. s. 397-413. kinds of birds. It appears that 

50 In his 'Essays on Nat. Hist..' Aristotle was well aware of the 

Mr. Hewitt gives analogous change in mental disposition in old 

th hen-pheasants in ' Journal hens. The case of the female deer 

Di Horticulture, July 12, 18-34, p. 37. acquiring horns is given at p. 513. 



Chap. XIII. REVERSION. 27 

racters properly confined to the female are likewise acquired 
by the male ; the capon takes to sitting on eggs, and will 
bring lip chickens ; 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 office of 
a sitter." 57 That admirable observer Reaumur 5S asserts that 
a cock, by being long confined in solitude and darkness, can 
be taught to take charge of young chickens; he then utters 
a peculiar cry, 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 mammary glands retain this capacity in a latent 
condition. 

We thus see that in many, 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 59 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 grandparent 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 

57 < Cottage Gardener,' 1860, p. 5D Sir H. Holland, < Medical Notes 
379. and Reflections,' 3rd edit., 1855, p< 

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

AMERICAN ETHNOLOGY- 



189S 
LIBRARY 



28 INHERITANCE. Chap. SHE 

unequally developed : this is well known to he 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. 60 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 flesus 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 Achatinellae, 61 are as often sinistral as 
dextral. I will give an analogous case in the great articulate 
kingdom : the two sides of Verruca 62 are so wonderfully 
unlike, that without careful dissection it is extremely difficult 
to recognise the corresponding parts on the opposite 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 63 in 
which the flower, according as it stands on the one or other 
side of the spike, is unequally developed. In all the foregoing 

- - 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 
inter 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 yet simplest cases of characters lying dormant 
are. perhaps, those previously given, in which chickens and 
young pigeons, raised from a cross between differently coloured 

- - Steenstrup on the 'Obliquity p. 2 
of Flounders ': in * Annals and Mag. of '•- Darwin, 'Balanida?,' Ray 

Nat Hist.' May. 1865, p. 361. I also the appended 

_.von 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 

LI. lit . p. l x '!. crustaceans. 

01 Dr. E. von Martens, in 'Annals a Mormodes ignea : Darwin. ' For* 

and Mag. of Nat Hist' March. 1866, tilisation of Orchids,' ls62, p. 251, 



Chap. XIII. REVERSION. 29 

birds, are at first of one colour, but in a year or two acquire 
feathers 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-species. I will 
here add a somewhat different case, as it connects in a striking 
manner latent characters of two classes. Mr. Hewitt 64 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, spurs, 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 oi-. 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 65 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 

64 ' Journal of Horticulture,' July, Tegetmeier. 
1864, p. 38. I have had the oppor- 65 '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 old. or when the 
crossed turbit acquired the characteristic frill after its third 
moult, or when rarely-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. We should then have 
had a case of reversion, that is, of the reajipearance 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 supported 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 early 
youth. Black cats, we may feel assured, would occasionally 
produce by reversion tabbies : and on young black kittens, 
with a pedigree 66 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 Yonatt 6T asserts that even in 
hornless individuals "the rudiment of a horn may be often 
felt at an early age.'"' 

Xo doubt it appears at first sight in the highest degree im- 
probable that in every horse of every generation there should 

66 Carl Vogt, 'Lectures on Man,' 6: ' On Cattle,' p. 17-i. 

Ecg. translat., 183-i, p. -ill. 



Ciiai\ XIII. KE VERSION. 31 

be a latent capacity 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 colour 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 chiefly 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 grandparents or more remote pro- 
genitors of easy detection. Reversion is likewise almost in- 
variably the rule, as Mr. Sedgwick has shown, with certain 
diseases. Hence we must conclude that a tendency to this 
peculiar form cf transmission is an integral part of the 
general law of inheritance. 

Monstrosities. — A large number of monstrous growths and 



32 INHERITANCE. Chap. XIII. 

of lesser anomalies are admitted Toy 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 peloria, the change is generally looked at by botanists as 
a return to the primitive state. But Dr. Maxwell Masters, 6S 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 would 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 tlie 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 front 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 individual 
plant of the Linaria, 69 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 difficult 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 brilliant colours, and serve as an envelope to the 
flower, or a stamen produce efficient pollen; yet this occurs with 



68 ' Natural Hist. Review,' April. cases, Sitzb. d. k. Akad. d. Wissensch. : 

p. 253. See also his Lecture. Wien. B 1. LX. anl especially Bi. 

Royal Institution, March 16. 1860. LXVL. 1872 p. 125. 

On same subject, see Moquin-Tandon, ° 9 Verlot. • Des Varietes,' 1865, p. 

' Elements de Teratologic.' 1841, pp. 89; Xaulin. 'Nouvelles Archives du 

1 84-. 352 Dr. Peyritsch has collected Museum." torn. i. p 137. 
a large number of very interesting 



Chap. XIII. KEVEESION. 33 

many peloric flowers. That pelorism is not due to mere chance 
variability, but either to an arrest of development or to reversion, 
we may infer from an observation made by Ch. Morren, 70 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 tuberosa, 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 slips 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 maj'us, 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 



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



34 INHERITANCE. Chap. XIII. 

by ine. That this papilla Is a rudiment of a stamen was well shown 
by its various degrees of development in crossed plants between the 
common and the peloric Antirrhinum. Again, a peloric Galeob- 
dolon luteum, 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. B. Keeley, who sent me this plant, 
informs me that the flowers vary greatly, having from four to six 
lobes to the corolla, and from three to six stamens. 71 Now, as the 
members of the two great families to which the Antirrhinum and 
Galeobdolon belong are properly 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 different with the fifth 
stamen in the peloric Antirrhinum, which is produced by the 
redevelopment of a rudiment always present, and which probably 
reveals to us the state of the flower, as far as the stamens are con- 
cerned, at some ancient epoch. It is also difficult to believe that 
the other four stamens and the petals, 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 organs 
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 Corydalis solida. 1 ' 2 

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 suppressed, — the redevelopment of 

71 For othei* cases of six divisions "•- Godron, reprinted from the 

in peloric flowers of the Labiatas and ' Jlemoires de l'Acad. de Stanislas,' 

Scrophulariaceae, see Moquin-Tandon, 1868. 
' Teratologie.' p. U'2. 



Chap. XIII. HE VERSION. 35 

parts now in a more or less rudimentary 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 
being belongs ; 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 forea-oina; 
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 occasionally become peloric ; but many more cases have 
been observed in the Labiatae and Scrophulariacea3 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. 73 On this view of the nature of 
peloric flowers, and bearing in mind certain monstrosities in 
the animal kingdom, we 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 tourbillon 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 

73 Moquin-Tandon, ' Teratologic 1 ,' p. 186 : 



36 INHERITANCE. Chap. XIII. 

"believe that it is crowded with 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. 



hhap.xiv. inheritance : fixedness of character. 37 



CHAPTER XIY. 

INHERITANCE continued — FIXEDNESS OF CHARACTER — PREPOTENCY 
■ — SEXUAL LIMITATION — CORRESPONDENCE OF AGE. 

FIXEDNESS OP CHARACTER APPARENTLY NOT DEE TO ANTIQUITY OF INHERI- 
TANCE—PREPOTENCY OF TRANSMISSION IN INDIVIDUALS OF THE SAME 
FA3IILY, IN CROSSED BREEDS AND SPECIES ; OFTEN STRONGER IN ONE 
SEX THAN THE OTHER ; SOMETIMES DUE TO THE SAME CHARACTER 
BELNG 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 DOMESTICATED ANIMALS : AS 
EXHIBITED IN THE APPEARANCE AND DISAPPEARANCE OF INHERITED 
DISEASES; SOMETIMES SUPERVENING EARLIER IN THE CHILD THAN IN 
THE PARENT — SUMMARY OF THE THREE PRECEDING CHAPTERS. 

Tn the last two chapters the nature and force of Inheritance, 
the circumstances which interfere with its power, and the 
tendency to Reversion, with its many remarkable contingen- 
cies, were discussed. In the present chapter some other 
related phenomena will be 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 



88 IXHEBITAXCE. Chap. XIY. 

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 
ao-oreo-ate of slight 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 which 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 epoch, 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 de.-cent with 
modification, the species of the same genus have been modified 
since they branched off from a common progenitor, it follows 
that the characters by which they differ from one anothei 



Chap. XIY. FIXEDNESS OF CHAEACTEE. 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 
Ave shall immediately see, is a very different consideration 
from the strength or weakness of inheritance. 1 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, wid, 
as a general rule, continue to withstand them, and conse- 
quently be faithfully inherited. 

1 See Youatt on Cattle, pp. 92, 69, p. 325. Also Dr. Lucas, < UlUr6d 
78, 88, 163 ; and Youatt on Sh, ep, Nat.,' torn. ii. p. 310. 



40 INHERITANCE. Chap. XIV. 



Prepotency in the Transmission of Character. 

When individuals, belonging to the same family, bui 
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 resemble 
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, 2 but is rendered 
extremely complex by 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 ; 
fur 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 Xiebuhr, with the mental qualities of certain 
Roman families. 3 The famous bull Favourite is believed 4 
to have had a prepotent influence on the short-horn race. It 
has also been observed 5 with English race-horses that certain 
mares have generally 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. G. 31. 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., 5 torn. ii. pp. 112- 270. 

L20, 5 Mr. X.H.Smith, ' Observations 

3 Sir H. Holland, ' Chapters on on Breeding,' quoted in ' Encyclop. of 
Mental Physiology,' 1S52, p. 234. Rural Sports,' p. 278. 

4 • Gardener's Chronicle,' 1860 p. 



Chap. XIY. PREP0TENC1* OF TRANSMISSION. 41 

The truth of the principle of prepotency comes out 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 power 
that they are so highly valued for exportation. 6 Godine has given 
a curious case of a ram of a goat-like breed of sheep from the Cape 
of Good Hope, which produced offspring hardly to be distinguished 
from himself, when crossed with ewes of twelve other breeds. But 
two of these half-bred ewes, when put to a merino ram, produced 
lambs closely resembling the merino breed. Girou de Buzareingues 7 
found that c-f 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. The 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. 8 

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 9 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 w T ho 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, spots, and runts, and reared many 
mongrels and recrossed them ; and though the crest on the head 



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

der Xatur,' b. ii. s. 170. See Sturm, 8 Mr. Orton, 'Physiology of Breed- 

' Uebet Racen,' 1825, s. 104-107. ing,' 1855, p. 9. 

For the niata cattle, see my ' Journal 9 Boitard and Corbie, 'Les Pigeons,' 

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

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



12 INHERITANCE. Chap. XIY. 

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 10 assert that this is 
the invariable result of crossing trumpeters with other breeds : 
Xeumeister. 11 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 B that the 
crossed offspring of a trumpeter were crossed with trumpeters fcr 
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 which 
transmits its characters faithfully, but which, when crossed with 
any other race, has the feeblest power of transmittiug its two chief 
characteristic qualities. 

I will give oue 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. 13 So that it is certain that this breed very 
seldom has the power of transmitting its peculiar plumage to its 
ss d 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 ! M 

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 peas, 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- 
'• spotted, brown or majue-seeded pea, the offspring seems to lose 



" 'Les Pigeons,' pp. 168, 198. Mr. Hewitt, in 'The Poultry Book, 

11 'Das Gauze,' &c, 1837, s. 39. by Tegetmeier, 1866. p. 224." 

n ' The Pigeon Book,' p. 46. 14 Boitard and Corbie, "Les Pigeons, 

18 ' Physiology of Breeding.' p. 22 ; 1824, p. 226. 



Chap. XIV. PREPOTENCY OF TRANSMISSION. 43 

K nearly all the characteristics of the white-flowered and white- 
" seeded varieties ; and this result follows whether these varieties 
" have been used 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 15 
that this is the case with plants. To give one instance: when 
JS'icotiana paniculata and vincaejiora are crossed, the character of 
J\ T . paniculata is almost completely lost in the hybrid; but if N. 
quadrivdlvis be crossed with N. vincceflora, this latter species, 
which was before so prepotent, now in its turn almost disappears 
under the power of JV. 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 ninny. 16 The male pheasant, judging 
from Mr. Hewitt's descriptions, 17 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, 



13 ' Bastarderzeugung,' s. 256, 290, and this is generally accounted for 
&c. Naudin (' No uvelles Archives du by the males of both species trans- 
Museum,' torn. i. p. 149) gives a mitting with greater power this part 
striking instance of prepotency in of their structure ; but a compound 
Datura stramonium when crossed with hybrid which I saw in the Zoological 
two other species. Gardens, from a mare by a hybrid 

16 Floarens, ' Longevity Humaine,' ass-zebra, closely resembled its mother 

p. 144, on crossed jackals. With in its tail. 

respect to the difference between the 17 Mr. Hewitt, who has had such 
mule and the hinny, I am aware that great experience in raising these 
this has generally been attributed to hybrids, says (' Poultry Book,' by 
the sire and dam transmitting their Mr. Tegetmeier, 1866, pp. 165-167) 
characters differently ; but Colin, that in all, the head was destitute of 
who has given in his 'Traite Phys. wattles, comb, and ear-lappets; and 
Comp.,' torn. ii. pp. 537-539, the all closely resembled the pheasant in 
iullest description which I have met the shape of the tail and general con- 
with of these reciprocal hybrids, is tour of the body. These hybrids 
strongly of opinion that the ass pre- were raised from hens of several 
ponderates in both crosses, but in an breeds by a cock-pheasant ; but 
unequal degree. This is likewise the another hybrid, described by Mr. 
conclusion of Flourens, and of Bech- Hewitt, was raised from a hen- 
stein in his ' Naturgeschichte Deutsch- pheasant, by a silver-laced Bantam 
lands,' b. i. s. 294. The tail of the cock, and this possessed a rudimeuta] 
hinny is much more like that of the comb and wattles. 
horse than is the tail of the mule, 



14 INHERITANCE. Chap. XIV. 

for hybrids raised from five differently coloured liens 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 (Anxer cegyptlacus) ; and al- 
though I will 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 species, race, or individual being 
prepotent over the other in impressing 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 ls 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 19 
to be all erroneous. If we confine our view to the domesticated 
races of a single species, or perhaps even to the species 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; 20 but conspicuous exceptions have passed under my 
own eyes. It seems that the ram usually gives its peculiar horns 
and fleece to its crossed offspring, and the bull the presence or 
absence of horns. 

In the following chapter on Crossing 1 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 absorbs 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 prepotency. 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 by different species, when crossed, either 
with prepotent force or singular feebleness. It is obvious, 

18 ' L'Hered. Nat.,' torn. ii. book ii. Museum,' torn. i. p. 148) has arrived 
eh. i. at a similar conclusion. 

19 ' Bastarderzeugung,' s. 264—2 20 'Cottage Gardener,' 18 oil, pp. 
N'au lin (' Nouvelles Archives du 101, 167. 



Chat. XIV. PEEPOTENCY 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 mongrelised and already variable form. 21 Erom 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 apparently depends 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 by seed, have a latent 
tendency to become uniformly coloured, but when once crossed 
by a uniformly coloured variety, they ever afterwards fail to 

21 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 striking instances of this result by crossing intentionally mongrelised 

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

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



£8 INHERITANCE.. Chap. XIY. 

produce striped seedlings. 22 Another ease is in some respects 
more curions : 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. 23 Xow I crossed the peloric 
snapdragon (Antirrhinum majus), 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 2i 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 
•-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- 
b _ ns, two were in an intermediate condition between the 
peloric and normal state, and thirty-seven were perfectly 
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 
ci as 1. For in all the Scrophulariacea?, and esjDecially in 
the genera Antirrhinum and Linaria, there is, as was shown 

■- Verlot, 'De* Yarietes,' 1865, p. 66. 

- 3 Moquin-Tandon, 'Teratologic,' p. 191. 

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



Chap. X1Y. SEXUAL LIMITATION. 47 

in the last chapter, 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 varying so much in strength, even in regard 
to the same character, in different animals, — from its running 
either equally in both sexes, or, as frequently is the case with 
animals, but not with plants, much stronger in one sex than 
the other, — from the existence of secondary sexual charac- 
ters, — from the transmission of certain characters being 
limited, as we shall immediately see, by sex, — from certain 
characters not blending together, — and, perhaps, 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. 

Inheritance as limited by 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. 



18 INHERITANCE. Chap. XIV. 

Dr. P. Lncas has shown 35 that when a peculiarity; in no manner 
connected with the reproductive organs, appears in either parent, 
it is often transmitte 1 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 hemorrhagic 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 attaeed 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 

seSj -bowing 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, 26 
generally h Ids g ■.. 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 lite in either sex are commonly trans- 
mitted to both sexes. I am, however, far from supposing that this 
is the sole determining cause. 

A few details from the many cases collected by Mr. Sedgwick, 27 
may be here given. Colour-blindness, from some unknown cause, 
shows itself much oftener in males than in females ; in upwards of 
two hundred cag - tted 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, 



23 • L'Here I. Nat.,' torn. ii. pp. 137- 2: On Sexual Limitation in Heredi- 

1*55. v. ilso, Mr. Sedgwick's four tary Diseases, "Brit, an I For. Med.- 

Btemoirs, immediately to be referred Chirurg. Review/ April 1861, p. 477; 

io. July p7 1^8 ; April 1863, p. Uo ; and 

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

32. inriuence of Age in Hereditary Da ease.' 



Chap. XIV. SEXUAL LIMITATION. 49 

nevertheless, in one instance in which 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 affect 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, twelve 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 
with the hemorrhagic 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 
peculiarity, — the grandmother, daughter, and great-grand -daughter 
having transmitted it in a latent state. Hence we have, as Mr. 
Sedgwick remarks, a double kind of atavism or reversion; each 
grandson apparently receiving and developing the peculiarity from 
his grandfather, and each daughter apparently receiving the latent 
tendency from her grandmother. 

Prom the various facts recorded by Dr. Prosper Lucas, Mr. 
Sedgwick, and others, there can be no doubt that peculiarities first 
appearing in either sex, though not in any way necessarily or 
invariably connected with that sex, strongly tend to be inherited by 
the offspring 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, 
we 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 differ also in the development of fat in 
the tail and in the outline of the forehead. These differences, 
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 difference 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, 28 and, judging from analogy, more than in the 
aboriginal parent-species. The peculiar colour called tortoise-- 



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



50 INHERITANCE. Chap. XIY. 

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 
Gallus bankiva; and consequently have originated under domesti- 
cation. In certain sub-varieties of the Game race we have the 
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 
the whole great family the two sexes do not often differ much ; and 
the males and females of the parent-form, the C. Uuia, 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 ami 
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 

- diminished, under domestication. We see 

this in the small size of the tusks in our improved breeds of 

i g, in comparison with those of the wild boar. There 

►f fowls, iii which the males have lost the fine- 

flowinff tail-feathers and hackles : and others in which there 

is no difference in colour between the two sexes. In some 

- - 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 Gallus. On the 



Chap. XIV. AT CORRESPONDING PERIODS. 51 

whole, as far as I can judge, new characters are more apt 
to appear in the males of our domesticated animals than in 
the females, 29 and afterwards to be inherited exclusively 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. 

Inheritance at corresponding 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 embryo 
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 embryo, 
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 many 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 

29 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 INHERITANCE. Chap. XIV. 

tlieir parent-forms, present conspicuous differences, both in 
their immature and mature states. Look at the seeds of tho 
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 poultry, 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 *1k <:•]>. early maturity, including the early develop- 
ment of the teeth, and with 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, 
perhaps, offers the best instance ; fur in the breeds which 
transmit 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 eyebrow, and in the loss of certain instincts ; — the cocoons 
differ in size, shape, and 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. AT COKKESPONDING PERIODS. 53 

in life, yet are inherited at tlie same period at which they 
first appeared. 

In the Lambert family the porcupine-like excrescences appeared 
in the father and sons at the same age, namely, about nine weeks 
after birth. 30 In the extraordinary hairy family described by Mr. 
Crawfurd, 31 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 corresponding 
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. 32 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 peculiarity has ceased. Of course all the birds 
" emanating from this stock have black wings and tails the first 
year." 33 A curious and somewhat analogous account has been 
given 34 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, which 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 afford evidence in some respects of less value 



30 Prichard, ' Phys. Hist, of Man- 32 ' Das Ganze der Taubenzucht,' 
kind,' 1851, vol. i. p. 349. 1837, s. 24, tab. iv., fig. 2 ; s. 21, tab. 

31 'Embassy to the Court of Ava,' i., tig. 4. 

vol. i. p. 320. The third generation 33 Kidd's ' Treatise on the Canary,' 

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

'Narrative of the Mission to the 34 Charlesworth, 'Mag. of Nat, 

Court of i\ra,' 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 process like inoculation, and the child is from the first 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. 
Yitus's dance, showing that an unusually early or late tendency to 
the disease is inheritable. 35 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 parent 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 36 
cautions the physician to look closely to the child at the period 
when any grave inheritable disease attacked the parent. Dr. 
Prosper Lucas/ 7 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. 

A- tlie subject is important, it may be well to give a few 
instances, simply as illustrations, not as proof ; for proof, 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 from the rule occurs, the child is affected some- 
what earlier in life than the parent. In the family of Le Compte 
blindness Mas inherited through three generations, and no less 
than twenty-seven children and grandchildren 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. 3S 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. 39 



35 Dr. Prosper Lucas, ; HereJ. Nat.,' children and grandchildren is given 

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

3,i4 L'Hcred. dans les Maladies.' judging from the paper rir-t published 

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

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

37 « L'Hered. N'at.,' torn. ii. p. 850. has been so kind as to send me a copy. 
- Igwick, ' Brit, and For. Med.- 3j Prosper Lucas, 'Hered. Nat. 

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



Chap. XIV. AT CORRESPONDING PERIODS. 55 

So with deafness, two brothers, their father and paternal grand- 
father, all became deaf at the age of forty. 40 

Esquirol 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 could 
be given, as of a whole family who became insane at the age of forty. 41 
Other cerebral affections sometimes follow the same rule, — 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. 42 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. 43 

I will give only two other cases, which are interesting as 
illustrating the disappearance as well as the appearance 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 about twelve years old 
suffered almost every week from severe headaches, which were 
relieved only by a recumbent position 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. 44 

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

40 Sedgwick, ibid., July, 1861, p. 1863, p. 449, and July, 1863, p. 162 , 
202. Dr. J. Steinan, ' Essay on Hereditary 

41 Piorry, p, 109 ; Prosper Lucas, Disease,' 1843, pp. 27, 34. 

torn. ii. p. 759. 44 These cases are given by Mr. 

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

43 Prosper Lucas, torn. iii. pp. 678, Stewart, in ' Med.-Chirurg. Review, 
700, 702 ; Sedgwick, ibid., April, April, 1863, pp. 449, 477. 



56 IXHEEITANCE. 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. Lucas 45 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." So 
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 embiyo 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. 

45 '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 young or 
old, differ from one another and from those of the parent- 
species : — 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 casts 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 symmetry, may be transmitted, 'i 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. 
S3o 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 inheritance 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 
very same peculiarity, as the weeping habit of trees, silky 
feathers, &c., may be inherited either firmly or not at all by 
different members of the same group, and even by different 



58 INHERITANCE. Chap. XIV. 

individuals of the same species, though treated in the same 
maimer. In this latter case we see that the power of trans- 
mission is a quality which is merely individual in its attach- 
ment. As with single characters, so it is with the several 
concurrent slight differences which distinguish sub-varieties 
or races ; for of these, some can he propagated almost as truly 
as species, whilst others cannot he 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 c r- 
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 itself 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, whilst living 
under their natural conditions, when domesticated have vari< d 
in the most diversified manner, that is, have failed to transmit 
their original form ; so that no character appears to be 
absolutely fixed. We 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 force by the combined 
action of the two parents, that it counteiacts its own power, 
and a new modification is the result. 

In many eases the failure of the parents to transmit their 

likeness is due to the breed having b< en at some former period 

i ssed; and the child takes after his grandparent or more 

remote ancestor of foreign blood. In other cases, in which 

the breed has not be«n crossed, hut some ancient charactet 



Chap. XIV. SUMMARY. 59 

has been lost through, variation, it occasionally reappears 
through reversion, so that the parents apparently fail to 
transmit their 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-generations, a flower 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 intimately commingled state. So it is with animals of 
crossed parentage, which 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 group 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-grown animals, should retain characters, during 
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 ready 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, borh 
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 crossing, 
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 INHERITANCE. 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 
prepotency of every other race. Prepotency of transmission 
may be equal in the two sexes of the same species, but often 
runs more strongly in one sex. It plays an important part 
in determining the rate at which one race can be mollified 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 present 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 
powei"S 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, Ave can understand how it is that most 
animals display from the germ to maturity such a marvellous 
su v ssion of characters. 



Chap. XIV. SUMMARY. 61 

Finally, though 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, 
with 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. 



62 ON CKOSSING AS A CAUSE. Chap. XV. 



CHAPTER XY. 

ON CROSSING. 

FREE INTERCROSSING OBLITERATES THE DIFFERENCES BETWEEN ALLIED 
BREEDS — WHEN THE NUMBERS OP TWO COMMINGLING BREEDS ARE 
UNEQUAL, ONE ABSORBS THE OTHER — THE RATE OF ABSORFTION DETER- 
MLNED 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 ; CHIEFLY OR EXCLUSIVELY THOSE WHICH HAVE SUDDENLY 
APPEARED IN THE LNDIYIDUAL — ON THE MODIFICATION OF OLD RACES, AND 
THE FORMATION OF NEW RACES, BY CROSSING — SOME CROSSED RACES 
HAVE BRED TRUE FROM THEIU FIRST PRODUCTION — ON THE CROSSING OF 
DISTINCT SIECIES 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, 
1 'V a ci mil dilation 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, when 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. No man in his senses 
would expect to improve or modify a breed in any particular 
manner, or keep an old breed true and distinct, unless he 



Chap. XV. OF UNIFORMITY 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. 1 The cele- 
brated agriculturist Marshall 2 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 imported into 
this country soon disappear, for their nocturnal and rambling 
habits render it hardly possible to prevent free crossing. 
Eengger 3 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 
offspring, of which fact evidence will hereafter be given ; for 

1 'Communications to the Board of England,' 1808, p. 200. 
Agriculture,' vol. i. p. 367. 3 ' S'augethiere von Paraguay. 

2 ' Review of Reports, North of 1830, s. 212. 



64 OX CROSSING AS A CAUSE. Caai\ XV. 

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

When listinct 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. 4 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 
belonoino; 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. When 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 5 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 l-10th, the blacks 1-1 Oth, and the 
' mulattoes, or people of intermediate degrees of colour, 

• 8-10ths of the whole number. In three centuries not 

• 1-1 00th part of the whites would exist." 

AVhen one of two mingled races exceed the other greatly 
in number, the latter will soon be wholly, or almost wholly, 
ed 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 ; 7 but the imported races no doubt 
were favoured. Piats maybe considered as semi-domesticated 
animals. Some snake-rats (^Mus alexandrinus) escaped in the 
Zoological Gardens of London, " and for a long time after- 

* Rengger, ' S'augethiere,' &c, s. maines,' p. 24, first called attention 

154. to this subject, and ably discussed it. 

4 White, « Regular Gradation in ' Rev. D. Tverman and Bennett, 

Man,' p. 14-3. ■ Journal of Voyages,' 1821-18Jf , vol. 

s Dr. W. F. Edwards, in his ' Ca- i. p. 3u0. 
r:u-U-rcs Phvsk>k'£. des Races Hu- 



Chap. XV. OF UNIFOKMITY OF CHAEACTEE. 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. 8 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; 9 and the requisite number has probably been much 
exaggerated. 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, 10 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 11 
speaks of the offspring of Mirabilis vulgaris, crossed during 
eight successive generations by M. longiflora, as resembling 
this latter sjoecies so closely, that the most scrupulous 
observer could detect " vix aliquam notabilem differentiam " 
or, as he says, he succeeded, " ad plenariam fere transmuta- 
tionem." But this expression shows that the act of absorp- 
tion was not even then absolutety complete, though these 
crossed plants contained only the l-256th 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, 12 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 greyhounds. As Stonehenge remarks, 

8 Mr. S. J. Salter, ' Journal Linn. crosses. Dr. P. Lucas, ' L'Heredite 
Soc.,' vo„ vi., 1862, p. 71. Nat.,' torn. ii. p. 308. 

9 Sturm, 'Ueber Racen, &c.,' 1825, 10 < Bastarderzeugung,' s. 463, 470, 
s. 107. Bronn, ' Geschichte der Na- u ' 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 12 ' The Dog,' 1867, pp. 179-184. 



66 OX CROSSING AS A CAUSE Chap. XV 

it might naturally be supposed that it would take several 
crosses to get rid of the heavy form of the bulldog ; but 
Hysterics, the 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, though fast as well as clever." I believe clever 
refers to skill in turning. Hysterics was put to a son cf 
Bedlamite, " but the result of the fifth cross is not as yet, I 
' f believe, more satisfactory than that of the fourth." On the 
other hand, with sheep, Fleischmann 13 shows how persistent 
the effects of a sing!e 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 bOOO, the twentieth cross 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 means acquire wool 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 the 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, ana especially, as Gartner insists, on 
prepotency of transmission in tne one form over the other. 
We have seen in the last chapter 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 niay be in 
this respect analogous. In all cases there will be more or less 
liability to reversion during many 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 

13 As quoted in the * True Principles of Breeding,' by C. H. Macknight 
mi Dr. 11. Madden, L865, p. 11. 



Chap. XV. OF TJNIFOEMITY OF CHARACTER. 67 

the act of crossing in itself tends to "bring "back long-lost 
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 would require before such a crossed body 
of animals would assume a uniform character within a limited 
area, no one ran 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 parent-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 tie same 
domestic race and of the same natural species, though largely 
governed by natural selection and by the direct action of the 
surrounding conditions. 

On the possibility of all organic beings occasionally intercrossing. 
— 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 been domesticated, have separate 



63 OX ALL ORGANIC BEINGS Chap. XV. 

sexes, 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 only at long intervals of time. 14 I 
will merely recall the fact that many plants, though herma- 
phrodite in structure, are unisexual in function; — snch as 
those called by C. K. Sprengel dicJwgamous, 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 oavu pollen is not fitted to fertilise its own 
stigma; or again, the many kinds in which curious mechani- 
cal contrivances exist, effectually 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 15 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 
(Latlnjrus odoraius) ; yet their flowers are certainly adapted 
for cross fertilisation. The varieties of the tomato and 
aubergine (Solanum) and the pimenta (Pimento, vulgaris?) 
are said 10 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 

14 With respect to plants. an admir- appeared on the same subject, more 

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

leehter-Yertheilung bei den Prlanzen : Drlpino. 

1867) has been published by Dr. Hil- 15 ' Teoria della Riproduzione Vege- 

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

general conclusions as I have done. 18 Verlot, ' Des Yarietes,' 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 country owing to premature fertilis- 
ation. There exist, however, some plants which under their 
natural conditions appear to be always self-fertilised, such as 
tho Bee Ophrys (Ophrys apifera) and 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 possibly 
be crossed. This was long thought to be the case with the 
Leersia oryzoides, 17 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 they 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 

17 Duval Jouve, ' Bull. Soc. Bot. 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 un- 
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 E. Heron crossed 
during many years white, black, brown, and fawn-coloured Angora 
rabbits, and never once got these colours mingled in the same 
animal, but often all four colours in the same litter. 18 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 wiil give an instance : a gentleman with a 
tair 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 
Umbs, are crossed with common breeds, the offspring are not inter- 
mediate in structure, but take after either parent. When tailless or 
hornless animals arc 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 Rengger, the hairless condition of the 
Paraguay dog is either perfectly or not at all transmitted to its 
m >ngrel 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 rive toes are crossed with other breeds, the 
chickens often have live toes on one foot and four on the other. 
Some crossed pigs raised by Sir R. 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 



18 Extract of a letter from Sir R. less condition of crossed South Ameri- 

Heron, 1838, given me by Mr. Yarrell. can dogs, see Rengs ' Saugethiere 

With respect to mice, s-.e ' Annal. des von Paraguay.' s. 152 : but 1 saw in 

Sc Nat.,' torn. i. p. 180; and I have the Zoological Gardens mongrels, 

heard of other similar cases. For from a similar cross, which were 

turtle-doves, Boitard and Corbie. ' Les hairless, quite hairy, or hairy in 

s,' & .. p. 2:)8. For the Game patches, that is, piebald with "hair. 

t . -The Poultry Book,' 186'3, p. For crosses of Dorking and other 

of tailless fowls fowls, see ' Poultry Chronicle/ vol. ii. 

bstein, 'Naturges. Deutsch.' p. 355. About the crossed pigs, 

b. iii. s. 403. Broun, 'Geschichte tract of letter from Sir R. Heron to 

dcr Natur,' b. ii. s. 170. gives analo- Mr. farrell. Fur other cases, see P. 

gous tacts with horses. On the hair- Lucas, 'L'Uered. Nat.' torn. i. p. 2121 



Chap. XV. NOT BLENDING. 71 

Clarke crossed the little, glabrous-leaved, annual stock (Matlriola), 
with pollen of a large, red-flowered, rough-leaved, biennial stock, 
called cocar deau 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. 19 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 hundred 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 purple, 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. 20 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 (Lathyrvs odoratvs), which has a dark reddish-purple 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 completely to the original mother-plant, the purple 

19 ' Internat. Hort. and Bot. Con- diate tints from similar crosses in the 
gress of London,' 1866. genus Verbascum. With respect to 

20 ' Bastarderzeugung,' s. 307. the turnips, see Herbert's ' Amarylli- 
Kolreuter ('Dritte Fortsetszung,' s. daceee/ 1837, p. 370. 

S4, 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 21 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. 

Prom 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 
Geoffrey St. Hilaire in regard to animals, that the transmission of 
characters without fusion occurs very rarely when species are 
I ; I know of one exception alone, namely, with the hybrids 
naturally produced between the common and hooded crow (Corvits 
and comix), which, however, are closely allied species, 
differing in nothing except colour. Nor have 1 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 superfcetation, — 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 
differences 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 sndden 
appearance of the characters in question. 



u • Xourelles Archives du Museum,' torn. i. p. 100, 



Chap. XV. CROSSING AS MODIFYING RACES. 73 



On the Modification of old Baces and the Formation of new 
Races oy 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 Eev. W. 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 grea,t 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. 22 
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." 23 To give an 
example, the " Oxfordshire Downs " now rank as an estab- 
lished breed. 24 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 
sheep. Mr. Spooner, after considering the various cases 

22 Richardson, ' Pigs,' 1847. pp. 37, part ii, : see also an equally good 
42 ; 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. 

23 See Mr. W. C. Spooner's excel- 2i ' Gardener's Chronicle,' 1867, pp. 
lent paper on Cross-Breeding, ' Jour- 649, 652. 

nal .Royal Agricult. Soc.,' vol. xx.. 



74 OX CROSSING AS A CAUSE Chap. XV 

winch, hive 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. 25 The Sebright bantam, which breeds as true as any 
other kind of fowl, was formed about sixty years ago by a 
complicated cross.' 26 Dark Brahmas, which are believed by 
come fanciers to constitute a distinct species, were un- 
doubtedly formed 27 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 variety of wheat, raised 
from two very distinct varieties, and which after six years' 
culture presented an even sample, has been recorded on good 
authority.-' 

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 distinct races, 
was hopeless : " they clung with superstitious tenacity to the 
" doctrine of purity of blood, believing it to be the ark in 
" which alone true safety could be found." 29 Nor was this 
conviction unreasonable : when two distinct races are crossed, 
ihe 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 first 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 ; 

23 ' Bulletin de la Soc. d'Acclimat.,' -'■ ; The Poultry Book,' by W. B. 

18 -. torn. ix. p. 463. See also, for Tegetmeier, 1866, p. 58. 
other cases, MM. Moll and Gayot, 28 'Gardener's Chronicle,' 1852, 

* bu Boenf,' 1860, p. xxxii. p. 765. 

2,i 'Poultry Chronicle/ vol. ii., M Spooner, in ' Journal Royal Agri« 

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



Ch^p. xy. of the modification of eaces. 75 

for though they niav themselves be uniform in character, 
the} 7 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 be 
decidedly unfavourable to the characters of either parent- 
breed. 30 

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 Eoitard and 
Corbie 31 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 ' 32 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 witti a white crescentio 
mark on the lower part of the breast, and with some white 
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? Animaux Domes ciques,' 31 ' Les Pigeons,' p. 37. 

Lorn. ii. p. 536, where this subject is 32 Vol. i., 1854, p. 101. 



76 ON CROSSING AS A CAUSE Chap. XV. 

regard to crossed varieties of plants, Mr. Beaton remarks 33 
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 34 
has given rive cases of hybrids, in which the progeny kept 
constant ; and hybrids between DiantJius 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 certainly 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 Eutiineyer's observa- 
tions there can be little doubt that this occurred with cattle ; 
but in most cases one form will probably have 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, 
Ehododendrons, 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 

33 ; Cottage Gardener,' 1856, p. 34 'Bastardei-zr^gung,' s. 553. 

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 

VARIOES CAUSES WHICH KEEP VARIETIES DISTINCT, AS THE PERIOD 

OF BREEDING- AND SEXUAL 1 REFERENCE — VARIETIES OF WHEAT SAID TO 
BE STERILE "WHEN CROSSED — VARIETIES OF MAIZE, VEEBASCUM, HOLLT- 
H< CK, GOURDS, MELONS, AND TOBACCO, RENDERED IN SOME DEGREE 
MUTUALLY STERILE — DOMESTICATION" ELIMINATES THE TENDENCY 10 
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, when 
crossed, are. with extremely few exceptions, quite prolific, — in 
some cases even more so than the purely-bred parent-races. 
The offspring, als >. raised from such crosses are likewise, as 
we shall see in the following chapter, 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 success rations. Dr. Broca x has remarked 

that no one has observed whether, for instance, mongrel dogs, 
bred inter 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, 
pins. dogs, and poultry, have' been crossed and recrossed in 
various ways, that any sterility, if it had existed, would from 
Wing injurious almost certainly have been observed. In 
1 • Journal de Physiolog.,' loir, ii., 1809, p. 385. 



Chap. XYI. THE CROSSING OF VARIETIES. 79 

investigating the fertility of crossed varieties man)' source of 
doubt 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 were 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 were 
found to exist, naturalists would simply infer that these 
breeds were descended from aboriginally distinct species ; and 
it would be scarcely possib'e 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 distinct 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 may 
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 sickle 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 interfere 
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, &o.,' 2 
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, Hamburgs, &c. 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 3 remarks, " the Talavera wheat, from 
flowering much earlier than any other kind, is sure to 

? Dec. 1863, p. 484. 3 Oa '• The Varieties of Wheat,' p. 6Q. 



SO CAUSES WHICH CHECK Chap. XYL 

continue pure." In different parts of the Falkland Islands 
the cattle are breaking np into herds of different colours ; 
and those on the higher ground, which are generally 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. 

Certain 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 dos;s of other breeds ; and the hairless dog of 
Paraguay mixes less readily with the European races, 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 4 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 5 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, ' S'augethiere von Para- and De Quatrefages. in ' Bull. Soc. 
guar.' s. 336. d'Acclimat./ torn, viii., July, 1861, 

4 Sec 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 civrions 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." 6 
With respect to fallow-deer, which live in a semi- domesti- 
cated condition, Mr. Bennett 7 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 wildness, 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 

8 For the Norfolk sheep, see Mar- 7 White's ' Nat. Hist, of Selbourne,' 

shall's 'Rural Economy 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 

1 Description of Faroe,' p. 66. For deer, see ' Some Account of English 

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



82 CAUSES WHICH CHECK Chap. XVI. 

this was the case. It lias often teen noticed that the 
dovecot pigeon seems to have an actual aversion towards the 
several fancy breeds ; 8 yet all have certainly sprung from a 
common progenitor. The Rev. TV. 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 coupling 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 fact, seeing 
1he great difference in structure between some breeds of pigeons, 
fowls, rjigs, 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 others 
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, 9 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, 10 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 

8 « The Dovecote,* by the Rev. E. S. 9 ' Cattle,' p. 202. 

Dixon, p. 155; Beehstein, 'Natur- 10 Mr. J. Wilkinson, in ' Remaiks 

. 'eutschlands,' Band iw, 1795, addressed to Sir J Sebright," 18J0, 

*. 17. p. 38. 



Chap. XVL THE CROSSING OF VARIETIES. 83 

yellow seecl u with pollen of a tall maize having red seed; and one 
head alone produced good seed, bnt 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. 12 In like manner Prof. Hildebrand 13 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 
with 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. 14 
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. blattaria 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 15 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 tbe white-flowered variety), when 
crossed with pollen of its own kind, yields more seed than when 

11 ' 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,' 

12 < Bastarderzeugung,' s. 87, 577. 1873) that this was an error. 

13 <Bot. Zeitung,' 1868, p. 327. 15 ' Kenntniss der Befruchtung,' s. 

14 Mr. Shirreff formerly thought 137 ; ' Bastarderzeugung,' s. 92, 181. 
C Gard. Chron.,' 1858, p. 771) that the On raising the two varieties from seed, 
offspring from a cross between certain see s. 307. 



84 CAUSES WHICH CHECK Chap. XVI 

crossed with that of the white variety; and so it is when differently 
coloured species are crossed. The general results may be seen in the 
Table at the end of his volume. In one instance he gives 16 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. hjchnitis, naturally fertilised by its own pollen, gave from an 
average of twelve capsules 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 90S, 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. 
lychn it is. when fertilised first by the white variety of V. blattaria, and 
then by the yellow variety of this species, yielded seed in the propor- 
tion of 622 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. blattaria, 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 
Yerbascum, made by him in the Botanic Gardens of Edinburgh. 17 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. hjchnitis 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 
(from six capsules), and by the pollen of the yellow variety (eight 
c ipsules), 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 91. Lastly, the white variety of V. blattaria 



19 * Bastarderzeugung,' s. 216. published in ' Journ. Asiatic Sec. of 

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



Chap. XXL THE CROSSING OF VARIETIES. 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 
ppecies were more fertile than the unions of dissimilarly- coloured 
varieties ; when all the cases are grouped together, the difference of 
fertility is as 100 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 
only twenty-six good capsules. Besides the foregoing experiments, 
the purple V. phceniceum 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. pftce- 
niceum by its own pollen. Hence it follows from Mr. 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. 18 

This remarkable fact of the sexual affinity 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 19 has remarked that variously- 
coloured double varieties of the Hollyhock (Alihea 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 
2Dlants all perfectly true to their kind; and seven produced forty- 
nine plants, half of which were true and half false. Mr. Masters of 



18 The folio wing facts, given by of their own variety than for that of 
Kolreuter in his ' Dritte Forisetzung,' the other ; this elective affinity, I 
ss. 34, 39, appear at first sight strongly may add of each species for its own 
to confirm Mr. Scott's and Gartner's pollen (Kolreuter, ' Dritte Forts.' s. 
statements; and to a certain limited 39, and Gartner, ' Bastarderz., j>jass»n) 
extent they do so. Kolreuter asserts, being a perfectly well-ascertained 
from innumerable observations, that power. But the force of the fore- 
insects incessantly carry pollen from going facts is much lessened by 
one species and variety of Verbascum Gartner's numerous experiments, for, 
to another ; and I can confirm this differently from Kolreuter, he never 
assertion ; yet he found that the once got (' Bastarderz.,' s. 307) an 
white and yellow varieties of Verbas- intermediate tint when he crossed the 
cum lychnitis often grew wild mingled yellow and white flowered varieties 
together : moreover, he cultivated of Verbascum. So that the fact of 
these two varieties in considerable the white and yellow varieties keep- 
numbers during four years in his ing true to their colour by seed does 
garden, and they kept true by seed ; not prove that they were not mutual- 
but when he crossed them, they pro- ly fertilised by the pollen carried by 
dnced flowers of an intermediate tint. insects from one to the other. 
Hence it might have been thought 19 < AmaryllidaceaB,' 1837, p. 366. 
that both varieties must have a Gartner has" made a similar observa- 
stronger elective affinity for the pollen tion. 



86 CAUSES WHICH CHECK Chap. XVI. 

Canterbury has given me a more striking case ; lie 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 ; 20 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 
rjropagating 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, 21 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 known ; but Sageret, 22 who ranked them according to 
their mutual fertility, considers the three forms above alluded to as 
varieties, as does a far higher authority, namely, M. Naudin.- 3 
Sageret 24 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. - : l Memoire sur les Cucurbitacea,' 

' -Mem. de l'Acad. de St. Petersburg,' 1826, pp. 46, 55. 

vol. iii. p. 127. See also C. K. - 3 -Annales des Sc. Nat.,' 4th 

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

s. 345. these forms as undoubtedly varieties 

31 Namely, Barbarines, Pastissons, of Cucurbita pepo. 

Giraumous: -Annul, des Sc. Nat.' 24 ' 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, 25 
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. glutinosa, and they 
yielded very sterile hybrids; but those raised from the var. perennis, 
whether used as the father or mother plant, were not so sterile as 
the hybrids from the four other varieties. 26 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. glutinosa. 21 

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 same 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 



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

26 Kolreuter was so much struck 
with this fact that he suspected that 
a little pollen of N. 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 conjointly 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 sufficient quantity, have 
any effect. The sole effect of mingling 
two kinds of polle-n is to produce in 
the same capsule seeds which yield 
plants, some taking after the one and 
some after the other parent. 

27 Mr. Scott has made some obser- 
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 pollen 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 STEEILITY. Chap. XYI 

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 when crossed. 

This hypothesis was first propounded by Pallas, 23 and has 
been adopted by several authors. I can find hardly any 
direct facts in its support; but unfortunately no one has 
compared, in the case of either animals or plants, the fertility 
of anciently domesticated varieties, when crossed with a 
distinct species, with that of the wild parent species when 
similarly crossed. Xo one has compared, for instance, the 
fertility of Gallus bankiva and of the domesticated fowl, when 
crossed with a distinct species of Gallus or Phasianus ; and 
the experiment would in all cases be surrounded by many 
difficulties. Dureau de la Malle, who has so closely studied 
classical literature, states 29 that in the time of the Romans 
the common mule was produced with more difficult}* 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. Greenland, 30 namely, that plants, 
known from their intermediate character and sterility to 
be hybrids between ^Egilops 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 

CJ -Act. Acad. St. Petersburg,' (1st series), p. 61. 
1780, part ii. pp. S4. 1 30 • Bull. Bot, Soc. de France,' EKkj. 

29 -Annales des Sc. Nat.' torn. xxi. 27th, 1861, torn. viii. p. 612. 



Chat. STL INCREASED FERTILITY FROM DOMESTICATION. 89 

that our domesticated pigs belong to at least two specific 
types, S. scrofa and indicus. Now 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 
Pallasian doctrine that long-continued domestication tends 
to eliminate that sterility which is natural to species when 
crossed in their aboriginal state. 

On increased Fertility from Domestication' and Cultivation. 

Increased fertility from domestication, without an y 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, 31 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, 
without 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 

31 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 INCEEASED FERTILITY Chap. XVL 

breed four times yearly, and to produce each, time at most 
six young ; the tame rabbit breeds six or seven times yearly, 
producing eacli time from four to eleven young ; and 
Mr. Harrison Weir 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 
remarkably 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 year, 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 they are four years old. 32 

Birds offer still better evidence of increased fertility from domesti- 
cation : the hen of the wild Gallus bunkiva lays from six to ten 
eggs, a number which would be thought nothing of with the 
domestic hen. The wild duck lays from five 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. lioia, I know not ; but the more thoroughly domesti- 



32 For cats and dogs, &c, see Bel- wild sow. see Bechstein's ' Xaturgesch. 

lingeri, in ' Annal. cles Sc. Nat.,' 2nd Deutschlands,' B. i., 1801, s. 534; for 

series, Zoolog., torn. xii. p. 155. For the domestic pig, Sidney's edit, of 

ferrets, Bechstein, ' Natnrgeschichte Youatt on the Pig, 1860, p. 62. With 

Deutschlands,' Band i., 1801, s. 78:5, respect to Lapland, see Acerbi's 

795. For rabbits, ditto, s. 1123, 1L31 ; 'Travels to the Xorth Cape,' Eng. 

and Bronn's ' Geschichte der Natur.,' translat., vol. ii. p. 222. About the 

B. ii. s. 99. For mountain sheep, Highland cows, see Hogg on Sheep. 

ditto, s. 102. For the fertility of the 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- 
?ated turkeys there invariably 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. 33 

With respect to j>lants, 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 comparison with the wild plant is enormous. 
Kb 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 their 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 cliance 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 Gallus bankiv% Pigeons,' p. 158. With respect to 

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

Nat. Hist.,' 2nd series, vol. i., 181-8, ('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 Tesetmeier's 

Adventures,' vol. 'ii. 1854, P. 413; Poultry Book,' 1866, pp. 280, 282), 

and for tame geese, 'Ornamental she there lays or ly 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 says from 
s. 46 ; and Boitard and Corbie ' Les ' eight to twelve eggs. 



92 GOOD FROM CROSSING. Chap. XYJI. 



CHAPTER XYII. 

OX THE ZOOD EFFECTS OF CROSSING, AND OX THE EVIL EFFECTS 
OF CLOSE INTERBREEDING. 

DEFINITION OF CLOSE INTERBREEDING — AFGMENTATIOX OF 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 INCESTEOFS MARRIAGES — FOWLS— PIGEONS — HIVE- 
BEES PLANT.-;, GENERAL CONSIDERATIONS ON THE BENEFITS DERIVED FROM 

CROSSING MELONS, FRFIT-TREES, PEAS, CABBAGES, WHEAT. AND FOREST- 
TREES— ON THE INCREASED SIZE OF HYBRID PLANTS, NOT EXCLFSIVELY 
DUE TO THEIR STERILITY — ON CERTAIN PLANTS WHICH EITHER NOR- 
MALLY OR ABNORMALLY ARE SELF-IMFOTENT, BET 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, has 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 ; whilst the good effects 
which almost invariably 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 be 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 generally 
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 opinion of 
that most experienced observer Sir J. Sebright, 1 that the evil 

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



94 GOOD FROM CEOSSIXG. 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 2 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 directly 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 
experienced observers, even when they do not advance the 
grounds of their belief, is of some little value. Xow almost 
all men who have bred many kinds of animals and have 
written on the subject, such as Sir J. Sebright, Andrew 

1 ■ The History of the Rise and Progress of the Killerby, .kc. Herds,' p 41. 



Chap. XYII. EVIL FROM INTERBREEDING. 95 

Knight, &c., 3 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, 
have 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 Kathusius, 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 Xathusius 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, from 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 fancy 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 

3 For Andrew Knight, see A. 227. Sir J. Sebright's Treatise ha« 
Walker, on ' Intermarriage,' 1838, p. just been quoted. 



96 GOOD FBOM CROSSING. Chap. XVIL 

cases, as briefly stated in tlie 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 utterly 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 BakewelFs Longhorns, which were 
closely interbred for a long period, has often been quoted; yet 
Youatt says 4 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 offspring of a half-brother and 
sister from Foljambe) was matched with his own daughter, grand- 
daughter, and great-granddaughter ; so that the produce 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. 5 Nevertheless Collings, who 
« ared 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 world. 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,' 3 



4 ' Cattle,' p. 199. the dams are given. Moreover, Cla- 

5 1 give this on the authority of rissa bore " only two bulls and one 
Nathusius, 'Ueber Shorthorn kind- heit'er, and in the next generation her 
vieh,' 18 "> 7, s. 71 {see also • Gardener's progeny became extinct." Analogous 
Chronicle,' 1860, p. 27<i)- But V.v. cases ot close interbreeding are given 
J. Storer, a large breeder of cattle. in a pamphlet published bv ^Ir. C. 
informs me that the parentage of Macknight and Dr. H. Madden, 'On 
Clarissa is not well authenticated. In the True Princip 1 es cf Breeding;' 
the rirst vol. of the 'Herd Book,' she Melbourne. Australia, 18G5. 

was entered as having six descents 6 Mr. Willoughby Wood, in ' Gar- 

from Favourite. " which was a palpa- dener's Chronicle,' 1855, p. 411 ; and 

b:e mistake," and in all subsequent 1860, p. 270. See the very clear 

editions she was spcien of as having tables and pedigrees given in Nathu- 

oniy four descents. Mr. Storer doubts fins' • Rindvieh,' s. 72-77. 
even about the four, as no names of 



Chap. XYH. EVIL FROM INTERBREEDING. 97 

was, that " to breed in-and-in from a bad stock was rain 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 Natkusius, 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 closely 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 ; 8 and their merit is now so fully recognised, that 
at fat-cattle shows a separate class has been formed for 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. 9 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, 

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

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

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

of Shorthorns in Ireland) informs me tion." 

that the raisers of the great families 8 Youatt on Cattle, p. 202. 

of Shorthorns carefully conceal their 9 ' Report British Assoc, Zoolog 

sterility an 1 want of constitution. He Sect.,' 1838. 
s4ds that Mr. Bates, after he had 



98 GOOD FROM CEOSSIXG. Chap. XVIL 

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." 10 The decrease in size from ancient 
times in the Chillrngham 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. Iso 
doubt this decrease in size may be largely attributed to less favour- 
able conditions of life ; yet animals roaming over large parks, and 
fed during severe winters, can hardly be considered as placed under 
very unfavourable conditions. 

With She 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 
fievei 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 m 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 Xaz flock has been bred 
for sixty years without the introduction of a single strange ram. 11 
Nevertheless, most great breeders of sheep have protested against 
close interbreeding prolonged for too great a length of time. 12 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;" 13 and what is probably of greater 
importance, the separate flocks will have been exposed to somewhat 
different conditions. 

15 Azara, ' Quadruples du Para- flock, ' Bull, de la Soc. d'Acclimat.,' 

guav.' turn. ii. pp. 354-. 368. I860, p. -177. 

11 For the case of the Messrs. 12 Nathusius, ' Eindvieh,' s. 65; 

Brown, see ' Gard. Chronicle,' 1855, Youatt on Sheep, p. 495. 
p. 26. For the Foscote flock, 'Gard. 13 « Gard. Chronicle,' 1861, p. 631 

Chron.,* I860, p. 416. For the Xaz 



Chap. XYIL EVIL FROM INTERBREEDING. 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, 14 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 shillings), 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 Eyelands 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, 
especially when the male is larger than the female. 15 

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 (Cervus 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, 16 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 e 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 



14 ' Journal R. Agricult. Soc.,' vol. ii. See also an excellent paper on 
xiv., 1853, p. 212. the same subjectin ' Gard. Chronicle,' 

15 Lord Somerville, 'Facts on 1860, p. 321, by Mr. Charles Howard. 
Sheep and Husbandry,' p. 6. Mr. 16 ' Some Account of English Deei 
Spooner, in ' Journal of Royal Agri- Parks,' by Evelyn P. Shirley, 1887. 
cult. Soc. of England,' vol. xx. part 



iCO GOOD FROM CROSSING. Chap, XVII 

too far. 17 But Sir J. Sebright, declares, 1 * 5 that by breeding in-and-in, 
by which he means matching brothers and sisters, he has actually 
seen the offspring of strong spaniels degenerate into weak and 
diminutive lapdogs. The Eev. W. D. Fox has communicated to 
me the case of a small lot of bloodhounds, long kept in the same 
family, which had become very 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 19 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 Pigs 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. at M. Legrain's invariable success 
175-188. in his experiments, that I wrote to a 

18 'The Ait of Improving the distinguished naturalist in Belgium 
Breed,' &c, p. 13. With respect to to inquire whether M. Legrain was a 
Scotch deerhounds, see Scrope's 'Art trustworthy observer. In answer, 1 
Dt' Deer Stalking.' pp. 350-353. have heard that, as doubts were ex- 

u> • Cottage Gardener,' 1861. p. 327. pressed about the authenticity of these 

20 Mr. Huth gives (• The Marriage experiments, a commission of inquiry 

of Near Kin.' 1^75. p. 302) from the was appointed, and that at a suc- 

• Bulletin de l'Acad. R. de .Med. do ceeding meeting of the Society (' Bull. 

g e ' (vol. ix.. 1866, pp. 287, de l'Acad. R. de Med. de Beigique/ 

. several statements made by a 1867. 3rd series, Tome 1, No. i to 

M. Legrain with respect to crossing b). Dr. Crocq repoxted " qu'il etait- 

brother and sister rabbits for rive or materiellement impossible que M. Le- 

six successive generations with no grain ait fait les experiences qu'il 

consequent evil results. I was so annonce." To this public accusation 

much surprised at thi* account, and no satisfactory answer was ma.ie. 



Chap. XYII. EVIL FEOM LNTEKBREEDLNU. 101 

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."- 1 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 22 
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 offspring 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 affected. 

Nathusius gives 23 an analogous and even more striking ca?e: 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 own 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 

21 Sidney's edit, of ' Youatt on the Col. Le Couteur, who has done so 
I'ig, 'I860, 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 

22 ' Journal of Royal Agricult. Soc. closely, twice pairing brothers and 
of England,' 18+6, vol. vii. p. 205. sisters, but nearly all the young had 

23 ' Ueber Rindvieh,' &c, s. 78. fits and died suddenlv. 



102 GOOD FE03I CEOSSING. Chap. XYIL 

when no injury is perceptible from moderately close interbreeding, 
yet, 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 



Almost all the animals as yet 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 pig 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 eases, 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 I will say but little. It has been 
discussed by various authors under many points of view. 25 



24 Sidnev on the Pig, p. 36. See cates have injured their cause by in- 
;\lso note. p. 3-k Also Richardson «n accuracies : thus it has heen stated 
the Pig. 1847, p. 26. (Devay, ' Dn Danger des Manages,' 

25 Dr. Dally has published an excel- &a, 1862, p. 14-1) that the marriages 
lent article (translated in the 'Anthro- or cou>ins hare been prohibited by 
polog. Review,' Hay, 1864-, p. 65), the legislature of Ohio; but 1 have 
criticising all writers who have main- been assured, in answer to inquiries 
Lained that evil follows from con- made in the United States, that thif 
s inguineous marriages. No doubt on statement is a mere fable. 

this -.ile or' the question many advo- 



Chap. XVII. EVIL FROM INTERBREEDING. 103 

Mr. Tylor 2G lias shown 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. 27 It is a curious 
problem how these prohibitions arose during early and 
barbarous times. Mr. Tylor 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 arcept these views, seeing that incest 
is held in abhorrence by savages such as those of Australia 
and South America, 28 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 Mr. 
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. MacLennau 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 judgment and caution. See also Mr. 
' Early History of Man,' 1865, chap. x. W. Adam, ' On Consanguinity in Mar- 

27 ' The Marriage of Near Kin,' riage ' in the ' Fortnightly Review/ 
1875. The evidence given by Mr. 1865, p. 710. Also Hofacker, ' Ueber 
Huth would, I think, have been even die Eigenschaften,' &c, 18"8. 

more valuable than it is on this and 28 Sir G. Grey's ' Journal of Expe- 

some other points, if he had referred ditions into Australia,' vol. ii. p. 243 ; 

solely to the works of men who had and Dobrizhoffer, ' On the Ablpones of 

long resided in each country referred South America.' 
to, and who showed that they possessed 



104: GOOD FROM CROSSING. Chap. XAH. 

instinctive feeling in man against incest any more than in 
gregarious animals. We know also how readily any prejudice 
or feeling may rise to abhorrence, as shown by Hindus in 
regard to objects causing defilement. 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, 29 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. 

Whether 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, 30 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 
tu the evil being very small. 

s. — In the case of the Fowl a whole array of authorities 
could be given against too close interbreeding. Sir J. Sebright 
iy 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. 81 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 



• Des ut of Man. 2nd. edit p. Review.' June. 187.".. 

52 *■. 31 • The Art of Impror'ag the 

urnal "t' Statistical Sec' June, Breed,' p. !3. 
ls7o. p, 153; and 'Fortnightly 



Ciiaf. XVIL EVIL FEOM INTERBREEDING. 105 

hatched from 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 — brings with it improved probability of 
" increased fertility." 32 

Mr. Wright states 33 that Mr. Clark, "whose fighting-cocks were 
" so notorious, continued to breed from his own kind till they lost 
" their disposition to fight, but stood to be cut up without making 
c: 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. 34 

An experienced writer 35 remarks that the same amateur, as 
is well known, seldom long maintains the superiority 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 buds 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 sufficient crossing to prevent deterioration." 33 



32 'The Poultry Book,' by W. B. and -in, viz., occasionally a hen with 
Tegetmeier, 1866, p. 245. her own son; " but they were cautious 

33 'Journal Royal Agricult. Soc.,' not to repeat the in-and-in breeding." 
1846, vol. vii. p. 205 ; see also Fergu- 3i 'The Poultry Book,' by W. B. 
son on the Fowl, pp. 83, 317 ; see also Tegetmeier, 1866, p. 79. 

* The Poultry Book,' by Tegetmeier, 35 ' The Poultry Chronicle,' 1854, 

1866, p. 135, with respect to the vol. i. p. 43. 

extent to which cock-fighters found 36 ' The Poultry Book,' by W. B 

that they could venture to breed in- Tegetmeier, 1866, p. 79. 



L06 GOOD FE03I CBOSSIXG. Chap. XVII 

We thus see that there is almost complete unanimity with 
poultry-breeders that, when fowls are kept at the same place, 
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. 37 Mr. Tegetmeier, 
who has carefully attended to poultry of all breeds, says 38 that 
Dorking hens, allowed to run with Houdan or Crevecceur cocks, 
" produce in the early spring chickens that for size, hardihood, 
" early maturity, and fitness for 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 considerably 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." 39 To 
this subject of the increased size of hybrids I shall presently return. 

With Pigeons, breeders are unanimous, as previously stated, 
that it is absolutely indispensable, notwithstanding the trouble 
and expense thus caused, occasionally to cross their much-prized 
lards 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, 40 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 thei 
have generally to be hatched under foster-mothers. Although 
highly-prized birds have invariably been subjected to much 
interbreeding, yet their extreme delicacy of constitution 
cannot perhaps be thus fully explained. Mr. Yarrell informed me 
that Sir J. Sebright continued closely interbreeding some owl- 

3, until from their extreme sterility he as nearly as i 
lost the whole family. Mr. Brent 41 tried to raise a breed of 
trumpeters, by crossing a common pigeon, and recrossing the 
daughter, granddaughter, great granddaughter, and great-, 
granddaughter, with the same male trumpeter, until he obtained 
a bird with \% of trumpeters blood; but then the experiment 
failed, for "breeding so close stopped reproduction." The ex- 
perienced Nnumeister 42 alfi - rts that the offspring from dove- 
ind various other breeds are "generally very fertile and 



37 'The Poultry Chronicle, 1 vol. i. A Treatise on Fancy P 

by J. M. Eaton, p. 56. 
he Poultry Book/ 1866, p. ' 41 ' The Pigeon Book,' p. 46. 

42 'Das Ganze der Taubenzacht,' 
39 Ibid. 1866. p. 167 : and ' Potdtry 18 7. s. 18. 
Chronicle,' vul. iii., 1855. p. 15. 



Chat. XY1L EVIL FROM INTEEBBEEDING. 10? 

hardy birds : " so again, MM. Boitard and Corbie/ 3 after forty-five 
years' experience, recommend persons to cross their breeds for 
amusement ; for, if they fail to make interesting birds, they will 
succeed under 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 44 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. 45 

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 otlier 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 46 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. 



43 < Les Pigeons,' 1824, p. 35. pp. 39, 77, 158 ; and 1864, p. 206. 

44 ' Proc. Entomolog. Soc.,' Aug. 46 ' Beitrage zur Kenntniss der 
Sth, 1860, p. 126. • Befruchtung,' 1844, s. 366. 

45 ' Journal of Horticulture,' 1861, 



108 GOOD FROM CBOSSTNG. Chap. XVII 

Herbert also says/ 7 " 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."" A gain, Professor Lecoq ascertained that crossed offspring 
are more vigorous and robust than their parents. 48 

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. 
In many of these experiments, the crossed plants yielded much 
more seed than the self-fertilised plants ; and I have never seen 
the reversed ease. 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 
seed- 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 ti jsed 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- 

gs 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. 
S \ crossed and six self-fertilised seeds of Jpomcea purpurea, from 
plants treated in the manner above described, were planted as soon 
as they had germinated, in pairs on opposit - . two pots, 

and rods of equal thickness were given them to twine up. Five 



Uidaceae,' p. 371. 4 ~ ' De la Fecondatiou,' 2nd edit., 1332, j.. 79. 



Ghaf. XY11. EVIL FKOM DsTEEBEEEDIXG. 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 prevailed 
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 MitpmIus hite<>s were fertilised with their 
own pollen, and others were crossed with pollen from distinct plants 
growing 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 Ipomcea 
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 growth 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 49 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 



49 ; Memoire sur les Cucurbitacees,' pp. 36, 28, 30. 

27 



110 GOOD FROM CROSSING. Chap. XVII. 

Here follows the evidence of an English gardener: 50 "I have this 
" summer met with better success in my cultivation of melons, in 
" an unprotected state, from the seeds of hybrids (*.e. mongrels) 
" obtained by cross impregnation, than with old varieties. The 
" offspring of three different hybridisations (one more especially, 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 51 believed that his seedlings from crossed varieties 
of the apple exhibited increased vigour and luxuriance; and M. 
Chevrenl 5 - alludes to the extreme vigour of some of the crossed 
fruit-trees raised by Sageret. 

By crossing reciprocally the tallest and shortest peas, Knight 53 
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 
sses 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 the parent-forms growing close alongside them. 

Wiegmann 54 made many crosses t>etween 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 >ix 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 d< stroyed 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 Royal Agricultural Society"'"' 
i win at. 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, 56 and he says " that 
" in the years 1795 and 17'JG, 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. Yiii., 5i ' Uebei die Bastarderzeugung, 1 

». 52. 1828, - . For Mr. Chaundy'a 

51 • Transact. Hort. S^e.,' vol. i. p. ca^e. see Loudon's ' Gard. Mag.' vul. 

vii. 1831, | . 

«" 'AnnaL de< S . N :..' " -Gardener's Chron.,' 18iH, p 
Bot., torn. vi. p. 1 1? 

53 'Philosophical Transactions' M ' Philosoph. Transact.,' 1 7f9, jr 

1799, p. 200. - 1. 



Chap. XY1I. EVIL FROM INTERBREEDING. Ill 

Here is a remarkable case : M. Clotzsch 57 crossed Pinus sylve&tris 
and nigricans, Quercus robur and peditnculata, Alnus glutinosa and 
incana, Ulmus campestris and effusa-; and the cross-fertilised seeds, 
as well as seeds of the pnre parent-trees, were all sown at the same 
time and in the same place. The result was, that after an interval 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 species. 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 58 
sums up his conviction on this head in the strongest terms. Kol- 
reuter 69 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 stutura por- 
" tentosa," their "ambitus vastissimus ac aUitudo valde 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, 60 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; 61 
but Gartner 62 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 growth 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 



bT Quoted in 'Bull. Bot. Soc. 60 'Die Bastardbefruchtung,' &c, 

France,' vol. ii., 1855, p. 327. 1885, s. 31, 41, 42. 

58 Gartner, ' Bastarderzeugung,' s. 61 Max Wichura fully accepts this 
259, 518, 526 et seq. view (' Bastardbefruchtung,' s. 43), 

59 ' Fortsetzung,' 1763, s. 29 ; as does the Rev. M. J. Berkeley, in 
1 Dritte Fortsetzung,' s. 44, 96 ; 'Act. 'Journal of Hort. Soc.,' Jan. 1866, 
Acad. St. Petersburg,' 1782, part ii., p. 70. 

p. 251; 'Nova Acta.' 1793, pp. 391, « 2 'Bastarderzeugung,' s. 394, 526, 

394; 'Nova Acta,' 1795, pp. 316, 52?. 

323. 



112 GOOD FROM CROSSING. Chap. XYLL 

their enormous roots. 63 have been transmitted to their progeny. 
The result in all cases is probably in part due 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 previously 
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 opposite contingencies of 
increased and diminished fertility. 

It is a perfectly well ascertained fact 64 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 sue, 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, hoi Is good in the 
iio^t striking manner with hybrid animals as well as with mongrels. 
rtlett, who has had such large experience says, " Among all 
" hybrids of vertebrated animals there is a marked increase of size. 5 ' 
He then enumerates many cases with mammals, including nionksys, 
and with various families of bh 

On certain Hermaphrodite Plants which, either normally or abiior* 
mall to be f> rtilised by pollen from a distinct individual 

or i 

The w to be given differ from the foregoing, as 

self-sterility is not here the result of long-continued close 
interbreeding. Th< se facts are. however, connected with our 
.: subject, 1 ecause a cross with a distinct individual is 
shown to be eithei ry 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 sonn - 8 to be fertile in any degree. 

63 k ..:"". 

63 Quoted by Dr. Marie, in ' Proc 
61 Gartner, ' B&starderzeugung,' s, .... - 18' , j 40. 



Uiiap. XYII. EYIL FROM INTERBREEDING. 113 

But I should not have noticed these plants, had it not been 
for the following cases given by Dr. Hildebrand : 66 — 

Primula sinensis is a reciprocally dimorphic species : Dr. Hilde- 
brand fertilised twenty-eight flowers 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 plant, 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, when the pollen and ovules belong to the same flower, 
than when belonging to two distinct individuals of the same form. 
Dr. Hildebrand has recently made analogous experiments on the 
long -styled form of OxaUs rosea, with the same result. 07 

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, yet, 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 wull commence with a plant 
belonging to a widely different family. 

Sixty-three flowers of Corydalis cava, borne on distinct plants, 
were fertilised by Dr. Hildebrand 68 with pollen from other plants of 
the same species; and fifty-eight capsules were obtained, including 
on an average 4*5 seed in each. He then fertilised sixteen flowers 
produced 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 



88 ' Botanische Zeitung,' Jan. 1864-, Berlin, 1866, s. 372. 

3. 68 International Hort. Congress. 

67 ' Monatsloricht Akad. Wissen.' London, 1866. 



114 GOOD FKOM CROSSING. Chap. XYII. 

had been possible, for the anthers not only touch the stigma, but 
the pollen-tubes were seen by Dr. Hilclebrand 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 placed 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. 69 Oncidium sphacelation 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 Royal Botanic 
Gardens of Edinburgh, also informs me (1864) that 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. divaricatum, 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.flexuosum 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 (J. microchilum was effective, 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. Riviere, 70 
with two plants of 0. cavendishianum, which were both self-sterile, 
but reciprocally fertilised each other. All these cases refer to the 
genus Oncidium, but Mr. Scott found that Maxillaria atro-nibem 
was "totally insusceptible of fertilisation with its own pollen," but 
fertilised, and was fertilised by, a widely distinct species, viz. M. 
sjuahns. 

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 Miiller informs me that at Desterro, in Brazil, he 



09 « Proc. Bot. Soc. of Edinburgh,' Linn. Soc.,' vol. viii. Bot., 1864, p 

May, IS jo : these observations are 162. 

given in abstract, and others are :o Prof. Lecoq, 'De la FJcondation, 

idded, in the ' Journ.d of Proc. of 2nd edit.. 1862, p. 7'3. 



Chap. XYII. SELF-IMPOTENT PLANTS. 115 

fertilised above one hundred flowers of the above-mentioned Oncl 
dium flexuosum, 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 any other plant of the same 
species were fertile. During the first three clays 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 distinct plant produced seed-capsules. On 
a subsequent occasion these experiments were repeated on a large 
scale with the same result. Fritz Miiller found that four other 
endemic species 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 
Rodriguezia. Oncidium crispum, however, differs from the fore- 
going species in varying much in its self-sterility ; some plants 
producing fine pods with their own pollen, others failing to do so 
in two or three instances, Fritz Miiller observed that the pods pro- 
duced by pollen taken from a distinct flower on the same plant, were 
larger than those produced by the flower's own pollen. In Epiden- 
drum cinnabar inum, 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 
capsules 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 Oncidium flexuosum, 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 flexuosum and of the Epidendrum zebra (nov. 
spec. ?) 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 poli en-masses, after an 
interval of eleven days., could not be distinguished except by the 
difference of their caudicles, which, of course, undergo no change. 
Fritz Miiller has, moreover, made a large number of crosses between 
orchids belonging to distinct species 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 pollen is 
applied. 

Fritz Miiller observed the poisonous action of the plant's own 
pollen in the above-mentioned Oncidium flexuosum, 0. uniccrne, 
pubes (J), and in two other unnamed species. Also in two species of 
Eoclriguezia, 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 proved that the flowers were, as might have been expected, 
fertile with pollen 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, 
in 1 not one pollen-grain emitted a tube. So that in this orchid the 
injurious action of the plant's own pollen is more rapid than with 
Oncidium flexuosum. Fight other flowers on the same raceme were 
fertilised with pollen from a distinct plant of the same species : two 
d: these were dissected, and their stigmas were found to be pene- 
trated by numberless pollen-tubes ; and the germens of the other 
six flowers became well developed. On a subsequent occasion many 
other flowers were fertilised with their own pollen, and all fell off 
dead in a few days ; whilst some flowers on the same raceme which 
la I 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 flexuosum, both the stigma and pollen quickly 
became dark brown, in the same manner as it 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 effectually preventing self-fertilisa- 
tion), but likewise prevents, as was ascertained in the case of the 
Notylia and Oncidium flexuosum, 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 ; 
tor 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 



Ohaf. XVII. SELF-IMPOTENT TLANTS. 117 

The same naturalist 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 
distinct plant, one of the three, and they yielded only two capsules. 
Lastly, five flowers were fertilised with pollen from a fourth 
plant growing at a distance, and all five produced capsules. 
Fritz Muller 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 riew is extremely probable, for he has since shown in a 
remarkable paper, 71 that in the case of some Brazilian species of 
Abutilon, which are self-sterile, and between which he raised some 
complex 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 state 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 readily 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 Lobelia fulgens, brought 
from separate places, and found 72 that their pollen was good, for he 
fertilised 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 of L.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 Verbascum nigrum 
Rrown in a pot was found by Gartner 73 capable of fertilising V. 
lychnitis and V. austriacum ; the ovules could be fertilised by the 



71 ' Jenaische Zeitschrift fur Katur- Naturalist.' 1874, p. 223. 

wiss.' B. vii. p. 22, 1872, and p. 441, 72 ' Bastarderzeuguug,' s. 64, 357- 

1873. A large part of this paper has 73 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/ 4 gives the case of three garden plants 
of Verbascum phoeniceum, which bore during two years many flowers ; 
these 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 Reseda 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 Midler 
produced by plants of Eschscholtzia calif ornica which were quite 
self-sterile in Brazil, yielded in this country plants which were only 
slightly self-sterile. 

It appears 75 that certain flowers on certain plants of Lilium 
Candida m can be fertilised more freely by pollen from a distinct 
individual than by their own. So, again, with the varieties of the 
potato. Tinzmann, 76 who made many trials with this plant, 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 flower's own stigma was 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 77 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. 78 I have received two accounts of P. 
guadrangularis never producing fruit from its own pollen, but 
doing so freely when fertilised in one case w r ith the pollen of P. 
ea, and in another case with that of P. edulis. But in three 



74 'Zweite Fortsetzung.' s. 10; developed :' Journal Asiatic Soc. Ben- 

'Dritte Forts..' s. 40. Mr. Scott like- gal,' 1867, p. 150. 
wise fertilised fifty-four flowers of 75 Duvernoy, quoted by Gartner, 

Verbascum phoeniceum, including two ' Bastarderzeugung,' s. 334. 
varieties, with their own pollen, and 76 • Gardener's Chronicle,' 1846. p. 

not a single capsule was produced. 183. 

Many of the pollen - grains emitted " ' Transact. Hort. Soc/ vol. vii., 

their tubes, but only a few of them 1830, p. 95. 

penetrated the stigmas ; some slight . 78 Prof. Lecoq. ' De la Fecondation,' 

effect however was produced, as many 1845, p. 70; Gartner, ; Bastarder« 

of the ovaries became somewhat zeu^ung/ s. 64. 



Chap. XVII. SELF-IMPOTENT 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 10° 
Fahr. above the former temperature, after the flowers were fertilised. 79 
With respect to P. laurifolia, a cultivator of much experience has 
recently remarked 80 that the flowers "must be fertilised with the 
pollen of P. coerulea, 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 : 81 
plants of Passiflora 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 241 seed. 

Beturning 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. Seedlings 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., 1864, p. 1168. Mr. Robert- 

80 ' Gardener's Chron.,' 1866, p. son Munro, in ' Trans. Bot. Soo. ; of 
1068. . Edinburgh, vol. ix. p. 399. 

81 ' Journal of Proc. of Linn. Soc.,' 



120 GOOD FKOM CROSSING. Chap. XVH 

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

The facts hitherto given relate to the much-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 wutlr 
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 inferior 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 fructitication of the others." In a letter written to me 
in 1839, Dr. Herbert says that he had 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 Eippe istrum aadicuw, 
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 H. butbulosum, 
. and vittatum ; the result was, that " the ovaries of the three 
'• first flowers soon ceased to grow, and after a few days perished 
" entirely : whereas the pod 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/ 3 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 



82 ' Araaryllidaeeae,' 1837. p. 371; 83 Loudon's 'Gardener's Magazine, 

'Journal ofHort Soc.,' vol. ii., 1S47, vol. xi.. 1835, p. 260. 
p. Id. 



Chap. XYII. SELF-IMPOTENT PLANTS. 121 

South Wales/ 4 asserts that Amaryllis belladonna bears many more 
seeds when fertilised by the pollen of Brunswigia (Amaryllis of some 
authors) jos phince or of B. multifiora, 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 Vallota (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." 85 These latter cases, 
however, relate to uncrossed sjDecies, 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 Arnaryllidaceae. 

In the experiments on the hybrid Hippeastrums, if Herbert had 
found that the pollen of two or three kinds alone had been more 
efficient 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, natalensis by the pollen of G. oppositiflorus. 86 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, 
fertilised 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, 

84 'Gardener's Chronicle,' 1850, p. Hort.,' 1861, p. 453. Lecoq, however 
470. (' De la Fecond.,' 1862, p. 369), states 

85 ' Journal Hort. Soc.,' vol. v. p. that this hybrid is descended from 
135. The seedlings thus raised were G. psittacinus and cardinal is ; but this 
given to the Hort. Soc. ; but I find, on is opposed to Herbert's experience, 
inquiry, that they unfortunately died who found that the former species 
the following winter. could not be crossed. 

86 Mr. D. Beaton, in < Journal of 



122 GOOD FROM CROSSING. Chap. XVII 

and in other cases all those down one side of the spike, with pollen 
of other varieties, and the remaining 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 hybrid 
i: made by a reciprocal cross." 

Conclusion. — Tliat plants should be self-sterile, although 
both sexual elements are in a fit 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 heterostyled plants, 
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 Beseda lutea), it 
is probable 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 parallel 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 Verbascum phoe- 



Chap. XVIL CONCLUSION. 123 

nieeum (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 given 
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 FEOM CROSSING. Chap. XVII. 

freely than the individuals of the 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 shown 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, pre- 
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 closelv related member 



Chap. XYIL CONCLUSION. 125 

of the same family were to he the victorious successor. The 
structure of niany 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 every 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. Xo doubt a false belief may, like a 
superstition, prevail widely; yet it is difficult 1o 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, seems never to be absolute, but only relative to 
animals of the same blood ; so that this sterility is to a certain 



126 GOOD FEOII CROSSING. Chap. XYIL 

extent analogous with that of self-impotent plants which. 
cannot be fertilised by their 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. 



Chap. XYIIL GOOD FROM CHANGED CONDITIONS. 127 



CHAPTER XYIIL 

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

ON THE GOOD DERIVED FROM SLIGHT CHANGES IN THE CONDITIONS OF LIEB ' 
■ — STERILITY FROM CHANGED CONDITIONS, IN ANIMALS, IN THEIR NATIVE 
COUNTRY AND IN MENAGERIES — MAMMALS, BIRDS, AND INSECTS — LOSS OP 
SECONDARY SEXUAL CHARACTERS AND OP INSTINCTS — CAUSES OF STERILITY 
— STERILITY OF DOMESTICATED ANIMALS FROM CHANGED CONDITIONS — 
SEXUAL INCOMPATIBILITY OF LNDIVIDUAL ANIMALS — STERILITY OF PLANTS 
FROM CHANGED CONDITIONS OF LIFE — CONTABESCENCE OF THE ANTHERS 
— MONSTROSITIES AS A CAUSE OF STERILITY — DOUBLE FLOWERS — SEEDLESS 
FRUIT — STERILITY FROM THE EXCESSIVE DEVELOPMENT OF THE ORGANS 
OF VEGETATION — FROM LONG-CONTINUED PROPAGATION BY BUDS — IN- 
CIPIENT STERILITY THE PRIMARY CAUSE OF DOUBLE FLOWERS AND 
SEEDLESS FRUIT. 

On the 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. Kow, 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. 

Tlie 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. 1 A sagacious 
observer, Bradley, writing in 1724., 2 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 Tear the Parties should change 
" with one another ; by which Means, I find the Goodness of the 
" Seed will be maintained for seTeral Tears. For Want of this 
" Use many Farmers have failed in their Crops and been great 
" Losers. 1 ' He then gives his own practical experience on this 
head. A modern writer 3 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 land 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 potato, 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 Vosges had become 
reduced in the course of fifty or sixty years in the proportion from 
120-150 to 30-10 bushels ; and the famous Oberlin attributed the 
surprising good which he effected in large part to changing the sets. 4 

A well-known practical gardener, Mr. Eobson, 5 positively states 



1 For England, see below. For Rev. D. Walker's ' Prize Essay of 
Germany, sec Met zger, 'Getreidearten,' Highland Agrk-ult. Soc.,' vol. ii. p. 
1841, s. 63. For France, Loiseleur- 200. Also Marshall's ' Minutes of 
Deslongchamps ('Consid. sur les Agriculture,' November, 1775. 
Cereales,' 1843, p. 200) gives nn- 4 Oberlin's ' Memou-3,' Eng. trans- 
merous references on this subject. For lat., p. 73. For I ancashire, see 
Southern France, see Godron, ' Florida Marshall's ' Review of Reports,' 1808, 
Juvenalis,' 1854. p. 28. p. 295. 

2 'A General Treatise of Hus- 5 • Cottage Gardener,' 1 £58, p. 186. 
Landry,' vol. iii. p. 58. Fur Mr. Robson's subsequent state- 

3 'Gardener's Chronicle and Agri- ments, see ' Journal of Hoitkulturc, 
cult. Gazette,' 1858. p. 247 ; and for Feb. 18, 1866, p. 121. For Mr 
the second statement, Ibid., 1850, p. Abbey's remarks on grafting, &c„ 
i02. On this same subject, see also Ibid., July 18, 1865, p. 44. 



Char XVIII. FROM CHANGED CONDITIONS. 129 

that he has himself witnessed decided advantage from obtaining 
bulbs of the onion, tubers of the potato, and various 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 place ; 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 £lf 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, 6 
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, 7 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 hardly credible 
that the advantage thus derived can be due to the seeds, 
especially if very small ones, obtaining in one soil some 

6 ; Mern. de l'Acad. des Sciences,' 7 < On the Varieties of Wheat,' p 

1790. p. 209. 52. 



130 STERILITY FROM Chap. X'VIII. 

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 "been anticipated that they would show the 
good effects of a change more plainly than do animals which 
continually wander about ; and this apparently 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 s 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 effects 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 effects 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. 
1 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 
kii.ds 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 
1 ears 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 

s 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,' 1^'3-t, vol. ii. ditions and from crossing widely dis- 

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

4 Origin of Species,' 18o9, 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. XVIII. CHANGED CONDITIONS. 131 

to the size, vigour, and fertility of their offspring ; so, on the 
other hand, certain other changes in the conditions of life 
cause sterility; and as this likewise ensues from crossing 
much-modified forms or 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 Geoffroy St.-Hilaire 9 
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 Reports 
subsequently published up to the year 1865. 10 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 

9 ' Essais de Zcologie Generale,' kept, and of these 1 species in 1 • 9 
1341, p. 256. ' have bred at least once during the 

10 Since the appearance of the first 20 years; of 28 Marsupialia, 1 in 2-5 
elition of this work, Mr. Sclater has have bred ; of 74 Carnivora, 1 in 3*0 
published (' Proc. Zoolog. Soc.,' 1868, have bred; of 52 Rodentia, 1 in 4*7 
p. 623) a list of the species of mam- have bred; and of Quadrumana 75 
nials 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. XVIII. 

different menageries would differ. Indeed, some animals in 
our Zoological Gardens have "become more productive since 
the year 1846. It is. also, manifest from F. Cuvier's account 
of the Jardin cles Planies, 11 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 mo-t remarkable cases, however, are afforded by animals 
kept in their native country, which, though perfectly tamed, quite 
healthy, and allowed some freedom, are absolutely incapable of 
breeding. Eengger, 1 ' 7 ' 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 work on the Amazons, strongly insists on similar 
cases; 13 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 by 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 io 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 14 that their 
'• breeding in the domestic state, or at hast in the half-domestic 
state in which the female elephants are gen-rally 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 15 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 



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

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

• ^-iu^ethiere von Paraguay,' u ' Embassv to the Court of Ava, 

IS I I, s. 49, 106, 118, 124, 201, 2u8, vol. i. p. 534." 

24;*. 265, 327. l5 ; Journal,' vol. i, p. 213. 

13 * The Naturalist on the Amazons,' 



Chap. XYII1. CHANGED CONDITIONS. 133 

the members of the pig family breed readily in our menageries ; 
even the Eed Elver hog (Potamochoeras penicillatus), from the 
sweltering plains of West Africa, has bred twice in the Zoological 
Gardens. Here also the Peccary (Dicoti/les torquatus) has bred 
several times ; but another species, the I), labiatus, 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 16 
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 different 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 Felidae have bred in various mena- 
geries, although imported from diverse climates and closely con- 
fined. Mr. Bartlett, the present superintendent of the Zoological 
Gardens, 17 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 species and produce hybrids 
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. 18 According 
to Eengger, two species of wild cats in Paraguay, though thoroughly 
tamed, have never bred. Although so many of the Felidae 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 
as>ured by the former superintendent, Mr. Miller, greatly increased 
their fertility. Mr. Bartlett, and there cannot be a more capable 



Rambles in ltdia, 



16 ' Saugethiere,' 


s. 


327. 






140. 






17 On 


the Breed 


ing 


; of tl 


ie Lar 


g er 


18 


Sleeman': 


Felidse, ' 


: Proc. Zool 

28 


og. 


Soc.,' 


1861, 


P- 


vol. 


ii. p. 


10. 



134 STERILITY FROM Chap. XVIII, 

judge, says, K 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.'"'* 

l\lany members of the Do^ family breed readily when confined. 
The Dhole is one of 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 
(Cants 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 Gc-netta has bred both here and in the Jardin des Plantes, and 
produced hybrids. The Berpestesfasci itus has likewise bred ; but I 
wu- formerly assured that the H. griseus, 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 
for this fact. In the nine-year Report it is stated that the bears 
had been seen in the Zoological Gardens to couple freely, but 
previously to l;<i3 had most rarely conceived. In the Pieports 
published since this date three species have produced young 
(hybrids in one case), and, wonderful to relate, the white Polar 
War has produced young. The badger (MeJes taxus) 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. 19 In 
Paraguay the native Nasua, though kept in pairs during many 
trs and perfectly tamed, has never been known, according to 
Rengger, to breed or show any sexual passion ; nor, as I hear from 
Mr. hates, 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 
ijj-rea ; and this animal is so closely allied to the guinea-pig, 



19 Wiegmarm's ' Arehiv fur Xaturgesch.,' 1837, s. 162. 



Chap. XYIII. CHANGED CONDITIONS. 135 

that it has been erroneously thought to be the parent form. 20 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 aguti) 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 Europe ; 
though, according to a recent statement, it has crossed with the 
rabbit. 21 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. 22 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. 23 

Monkeys, in the nine-year Beport 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.'- 4 A Macacus, according to Elourens, bred in Paris ; and 



20 Rengger, ' S'augethiere,' &c , s. Leporides, as described by Dr. Broca 

276. On the parentage of the guinea- ('Journal de Phys.,' torn. ii. p. 370), 

pig, see also Isid. Geoti'roy St.-Hilaire, has been positively denied, yet Dr. Pi- 

' Hist. Nat. Gen.' I sent to Mr. H. geaux ('Annals and Mag. of Nat. 

Denny of Leeds the lice which I col- Hist.' vol. xx., 1867, p. 75) affirms that 

lected from the wild aperea in La the hare and rabbit have produced 

Plata, and he informs me that they hybrids. 

belong to a genus distinct from those 22 ' Quadrupeds of North America, 

found on the guinea-pig. This is by Audubon and Bachman, 1846, p. 

important evidence that the aperea is 268. 

not the parent of the guinea-pig ; and 23 Loudon's ' Mag. of Nat. Hist.,' 

is worth giving, as some authors erro- vol. ix., 1836, p. 571 ; Audubon and 

neously suppose that the guinea-pig Bachman's ' Quadrupeds of North 

since b^ing domesticated has become America,' p. 221. 

sterile when crossed with the aperea. 24 Flourens, ' De l'lnstiuct,' &o., 

81 Although the existence of the 1845, p. 88. 



136 



STERILITY FROM 



Chap. a. /Ill 



more than one species of tins genus lias produced young in London, 
especially the Macacos rhesus, Tvhicli everywhere shows a special 
capacity to breed under confinement. Hybrids hare been produced 
both in Paris and London from this same genus. The Arabian 
baboon, or Oynocephalus Jiamadryas, 25 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 Lemm*s 
have produced hybrids in the Zoological Gardens. It is much 
more remarkable that monkeys very rarely breed when confined 
in their native country ; thus the Gay (Qebus azaroe) is frequently 
and completely tamed in Paraguay, but Eengger 2t5 says that it breeds 
no 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. 27 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. 28 

Birds. 

Birds offer in some respects better evidence than quadrupeds, 
from their breeding more rapidly and being kept in greater 
numbers. 29 We have seen that carnivorous animals are more 
fertile under confinement than most other mammals. The reverse 
holds good with carnivorous buds. It is said 30 that as many 
as eighteen species have been used in Europe for hawking, and 
several others in Persia and India ; 31 they have been kept in their 
native country in the finest condition, and have been flown during 
six, eight, or nine years ; " 2 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, 



25 See 'Annual Reports Zoo log. 
Soc' 1855, 1858, L863, 1864; -Times' 
newspaper, Aug. 10th, 184-7; Flou- 
rens, ' De I'Instinct,' ]>. 85. 

26 < S'augethiere.' &c, s. 34, 49. 

27 Art. Brazil, ' Penny Cyclop.,' p. 
363. 

28 ' The Naturalist on the Amazons,' 
vol. i. p. 99. 

29 A list of the species of birds 
which have bred in the Zoological 
Gardens from 1348 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 Gallinse, 83 
species have been kept, and 1 in '_" 7 
have bred ; of 57 Gralla?, 1 in 9 have 
bred; of 110 Prehensores, 1 in 22 
have bred ; of 178 Passeres, 1 in 
25 4 have bred; of 9-4 Accipitres, 
1 in 47 have bred ; of 25 Picariaj. and 
of 35 Herodiones, not one species in 
either group has bred. 

30 ' Lncyclop. of Rural Sports,' p. 
691. 

31 According to Sir A. Barnes 
(' 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. XYIIT. CHANGED CONDITIONS. 137 

and Sweden, there can be little doubt that, if possible, they would 
have been propagated. In the Jardin des Plantes, no bird of prey 
has been known to couple. 33 No hawk, vulture, or owl has ever 
produced fertile eggs in the Zoological Gardens, or in the old Surrey 
Gardens, with the exception, in the former place on one occasion, 
of a condor and a kite {Milvus niger). Yet several species, namely, 
the Aquila fusca, Hal-iwtus leucocephalus, Falco tinnunculus, F. sub- 
buteo, and Buteo vulgaris, have been seen to couple in the Zoological 
Gardens. Mr. Morris 31 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 {Bubo maximum) ; 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/ 5 35 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 Strix passer ina, 
breeding in captivity. 36 

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 37 remarks, 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 38 that the Fringilla (Spiza) 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 exception of the siskin ( Fringilla spinus), have 
reproduced their own kind. Even the bullfinch (Loxia pyrrhula) 
has bred as frequently with the canary, though belonging to 
a distinct genus, as with its own species. 39 With respect to the 
skylark (Alauda arvensis), 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. 40 
In the nine-year Eeport from the Zoological Society, twenty-four 



33 F. Cuvier, ' Annal. du Museum,' 38 'Ornithological Biography,' vol. 

torn. ix. p. 128. v. p. 517. 

3i ' The Zoologist.' vol. vii.-viii., 39 A case is recorded in ' The Zoo- 

1849-50, p. 2648. logist,' vol. i.-ii., 1843-45, p. 453. For 

35 Knox, 'Ornithological Ramhles the siskin breeding, vol. iii.-iv., 1845- 
in Sussex,' p. 91. 46, p. 1075. Bechstein, ' Stuben- 

36 'The Zoologist,' vol. vii.-viii., vogel,' s. 139, speaks of bullfinches 
1849-50, p. 2566 ; vol. ix.-x., 1851-2, making nests, but. rarely producing 
p. 3207. youno;. 

37 Bechstein, < Naturgesch. der Stu- 40 Yarrell's < Hist British Birds, 
benvogel,' 1840. s. 20. 1839, vol. i. j>. 412. 



138 STERILITY FROM Chap. XVIU 

insessorial 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 41 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. 42 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. 43 According to Bechstein 44 
the African Psittacus 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. 45 In Jamaica, a resident naturalist, 
Mr. E. Hill, 46 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 (Goura coronata and victories) produced hybrids; 



41 Loudon's ' Mag. of Nat. History,' worth's Mag. of Nat. Hist.' vol. 
rol. xix., 1836, p. 347. h., 1838, p. 492), "it is singular 

42 • Memoires du Museum d'Hist. that, amongst the numerous useful 
Nat.,' torn. x. p. 314: five cases of birds that are indigenous to Guiana, 
parrots breeding in France are here none are found to propagate among 
recorded. See also ' Report Brit. the Indians ; yet the common fowl is 
Assoc. Zoolog.,' 1843. reared in abundance throughout the 

43 'Annals and Mao;, of Nat. Hi=.t.,' country." 

Nov. 1868, p. 311. * 6 'A Week at Pert Royal,' 1855, 

** ' Stubenvogel,' s. 105, 83. p. 7. 

44 Dr. Hancock remarks (' Charles- 



Chap. XVIII. 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 Penan g, 
under a perfectly well-adapted climate, but never once bred. The 
Columba migratoria 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. leucocpphala.^ 

Gallinaceous birds of many genera likewise show an eminent 
capacity for breeding under captivity. This is particularly the case 
with pheasants, yet our English species seldom lays more than ten 
eggs in confinement ; whilst from eighteen to twenty is the usual 
number in the wild state. 48 With the Grallinaceae, 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 hatch her own eggs. 49 The American tribe of Guans 
or Cracidse are tamed with remarkable ease, but are very shy 
breeders in this country; 50 but with care various species were 
formerly made to breed rather freely in Holland. 51 Birds of this 
tribe are often kept in a perfectly tamed condition in their native 
country by the Indians, but they never breed. 52 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. 53 But many cases are recorded of their breeding : the caper- 
cailzie (Tetrao urogallus) has bred in the Zoological Gardens; it 
breeds without much difficulty when confined in Norway, and in 
llussia five successive generations have been reared : Tetrao tttiix 
has likewise bred in Norway; T. scoticus in Ireland; I 7 , umbellus 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 suffer, when 
cooped up hi small enclosures under a temperate climate, after 
freely roaming over desert and tropical plains or entangled forests ; 



47 Audubon, ' American Ornith- 51 Temminck, ' Hist. Nat. Gen. des 

ology,' vol. v. pp. 552, 557. Pigeons,' &c, torn. ii. pp. 456, 458 ; 

*' 8 Moubray on Poultry, 7th edit., torn. iii. pp. 2, 13, 47. 

p. 133. 52 Bates, 'The Naturalist on the 

49 Temminck, 'Hist. Nat. Gen. des Amazons,' vol. i. p. 193; vol. ii. p. 
Pigeons,' &c, 1813, torn. iii. pp. 288, 112. 

382 ; 'Annals and Mag. of Nat. Hist,,' 53 Temminck, ' Hist. Nat. Gen.,' &c, 

vol xii., 1843, p. 453. Other species torn. ii. p. 125. For Tetrao urogallus, 

cA partridge have occasionally bred ; see L. Lloyd, ' Field Sports of North 

as the red-legged (P. rubra), when of Europe,' vol. i. pp. 287, 314 ; and 

kept in a large court in France (see ' Bull, de la Soc. d Acclimat.,' torn. 

' Journal de Physique,' torn. xxv. p. vii., 1860, p. 600. For T. scoticus, 

294), and in the Zoological Gardens Thompson, 'Nat. Hist, of Ireland,' 

in 1856. vol. ii. 1850, p. 49. For T. cupido. 

50 Rev. E. S. Dixon, 'The Dove- 'Boston Journal of Nat. Hist.,' vol 
cote,' 1651, pp. 243-252. iii. p. 199. 



140 STERILITY FROM Chap. XYHL 

yet almost all the kinds have frequently produced young in the 
various European menageries, even the rnooruk {Caswirius bennetii) 
from New Ireland. The African ostrich, though perfectly healthy 
and living long hi 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. 54 Here we have another instance of fertility 
impaired, 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 Eev. 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 : Grus 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 GalUnida cidoropus in 
the Zoological Gardens. On the other hand, several birds belonging 
to this order will not breed in' their native country, Jamaica ; and 
the Psophia, though often kept by the Indians- of Guiana about 
their houses, " is seldom or never known to breed." 55 

The members of the great Duck family breed as readily in 
confinement as do the Columbae and Gallinee; and this, considering 
their aquatic and wandering habits, and the nature of their food, 
could cot have been anticipated. Even some time ago above two 
dozen species had bred in the Zoological Gardens; and M. Selys- 
Longchamps has recorded the production of hybrids from forty-four 
different members of the family; and to these Professor Newton has 
added a few more cases. 53 " There is not," says Mr. Dixon, 57 "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 58 
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 viduatd, although, 
according to Sir E. Schomburgk, 59 it is easily tamed, and is 
frequently kept by the Indians of Guiana. Lastly, with respect 



54 Marcel tie Sevres, ' Annales des ' Report Asiatic Soc. of Bengal,' May 

Sri. Nat.,' 2nd series, Zoolog., torn. 1 - 

xiii. p. 17^. 56 Prof. Newton, in ' Proc. Zoolog. 

35 Dr. Hancock, in ' Charlesworth's Soc.,' 1860, p. 336. 

: Nat, Hist.,' vol. ii., 1833. p. " : -The Dovecote and AvUry,' p. 

EL Hill, 'A Week at Port Royal,' 428. 

the Zoological Garden-.' 38 'Ornithological Biography,' vol. 

by P. L. Sclater, 1859, pp. 11, 12; iii. p. 9. 

'The Knowsley Menagerie,' bv Dr. 59 ' Geograph. Journal,' vol. xiii., 

Gray, 1846, pi. xiv.; E. Blyth, 1844 n. 32 



Chap. XVIII. CHANGED CONDITIONS. 141 

to Gulls, though many 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 argerrfatus) 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 Sphingidse 
rarely breed when thus treated. An entomologist 60 in Paris kept 
twenty-five specimens of Saturnia pyri, but did not succeed in 
getting a single fertile egg. A number of females of Orthosia munda 
and of Mamestra suasa reared in confinement were unattractive to 
the males. 61 Mr. Newport kept nearly a hundred individuals of 
two species of Vanessa, but not one paired ; this, however, might 
have been due to their habit of coupling on the wing. 62 Mr. 
Atkinson could never succeed in India in makiDg the Tarroo silk- 
moth breed in confinement. 63 It appears that a number of moths, 
especially the Sphingidse, when hatched in the autumn out of their 
proper season, are completely barren; but this latter case is still 
iuvolved in some obscurity. 64 

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 (Emberiza 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 Fcdco 
albidus returned to the dress of an earlier age. 65 Mr. Thomp- 
son, the superintendent of the Knowsley menagerie, informed 
me that he had often observed analogous facts. The horns 
of a male deer (Cervus canadensis) during the voyage from 
America were badly developed ; but subsequently in Faris 
perfect horns were produced. 

60 Loudon's ' Mag. of Nat. Hist.,' 5764 ; and Dr. Wallace, in ' Proc. 
vol. v., 1832, p. 153. Entomolog. Soc.,' June 4th, 1860, p. 

61 ' Zoologist,' vols, v.-vi., 1847-48, 119. 

p. 1660. 65 Yarrell's 'British Birds,' vol. i. 

62 ' Tonsact. Entomolog. Soc.,' vol. p. 506 ; Bechstein, ' Stubenvogel,' s. 
iv., 1845, p, 30. 185 ; ' Phiiosoph. Transact.,' 1772, p. 

63 'Transact. Linn. Soc.,' vol. vii. 271. Bronn (' Geschichte der Natur,' 
p. 40. Band ii. s. 96) has collected a number 

64 See an interesting paper by Mr. of cases. For the case of the deer, see 
Newman, in the 'Zoologibt,' 1857, p. ' Penny Cyclop.,' vol. viii. p. 350. 



142 STEPJLITY FEOM Chap. XVIIL 

\Ylien 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. YYe 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. Xo 
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 system 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 play no part ; and we shall presently 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 extremely different 
climates breed freely, many others when confined in their 
native land are completely sterile. Change of food cannot bo 



Ceap. XVIII. CHANGED CONDITIONS. 143 

the chief cause ; for ostriches, ducks, and many 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. Nor 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 66 that many animals in the Jar din 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 ; 67 and we are thus reminded of 
those plants which when cultivated refuse to be fertilised by 

66 'Journal de Physiologie,' torn. svbject, see F. Cuvier, in ' Annales du 
ii. p. 347. Museum,' tom. xii. p. 119. 

97 For additional evidence on this 



144 STERILITY FROM Chap. XVI1L 

their own pollen, but can easily be fertilised by that of a 
distinct species. Finally, we must conclude, limited 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 Domesticated Animals from chanr/ed 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; 68 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 undiminished 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. 69 I have, also, seen pigeons 

68 Numerous instances could be nesians of the Samoan Islands tamed 

given. Thus Livingstone ('Travel-,' pigeons; and the New Zealanders, as 

p. -217) states that the King of the Mr. Mantell informs me, kept various 

Barotsc, an inland tribe which never kinds of birds. 

had anv communication with white M Fur analogous cases with the 

men, was extremely fond of taming fowl, see Reaumur, 'L'Art de faire 

animals, and every young antelope was Eclore,' &c, 1749. p. 243; and CcL 

brought to him. Mr. Galton informs Sykes, in 'Proc. Zoolog. Soc.,' 1332, 

Bie that the Damaras are likewise &:e. With respect to the fowl not 

fond cf keeping pets. The Indians of breeding in northern regions, see 

South America follow the same habit. Latham's 'Hist, of Birds,' vol. viil, 

Capt Wilkes states that the Poly- 1823. p. 169. 



Chap. 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; 70 and according to Lord Somerville, 71 the merino-sheep 
which he imported from Spain were not at first perfectly fertile. It 
is said 72 that mares brought up on dry food in the stable, and 
turned out to grass, do not at first 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. 73 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 fourth 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, Mr. Orton says: 74 "the only geese in the valley are a few 
imported from Europe, and these refuse to propagate." In the 
Philippine Archipelago the goose, it is asserted, will not breed or even 
lay eggs. 75 A more curious case is that of the fowl, which, 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 fertility, 
for to raise two or three chickens from a nest of eggs was thought 
fortunate. In Europe close confinement has a marked effect 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 sixty out of the hundred were not hatched. 76 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 apparently lies in an innate sexual in- 



70 "Mem. par divers Savans," 'Acad. u 'The Andes and the Amazon,' 
des Sciences,' torn, vi., 1835, p. 347. 1870, p. 107. 

71 Youatt on Sheep, p. 181. 75 Crawfurd's < Descriptive Diet, oi 

72 J. Mills, < Treatise on Cattle,' the Indian Islands,' 1856, p. 145. 
1776, p. 72. ™ ' Bull, de la Soc. d'Acclimat., 

13 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. 77 
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 
f ' it frequently occurs with a mare to be put several times during 
" one or two seasons to a particular 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 vegetal le kingdom cases of sterility frequently 
occur, analogous with those previously given in the animal 
kingdom. But the subject is obscured by several circum- 
stances, presently to be discussed, namely, the contabescenco 
of the anthers, as Gartner has named a certain affection — 
monstrosities — d< nil ileness of the flower— much-enlarged fruit 
--and long -continued or excessive propagation by buds. 

It is notorious tla" many plants in our gardens and hot-houses, 
though preserved in the must 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 
- i Lo 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 Voyageuv Beige,' 1865, p. 66. 



Chap. XVIII. CHANGED CONDITIONS. 147 

specified, there are many plants in which the reproductive system 
has been seriously affected 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 7S that Alpine plants, although naturally loaded with 
seed, produce either few or none when cultivated in gardens. But 
exceptions often occur : the Drdba sylvestris, one of our most 
thoroughly 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. 79 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 vigorously. 

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, 80 it is hardly possible to 
give too much manure to most Gramineae, Cruciferae, and Legu- 
minosae, whilst succulent and bulbous-rooted plants are easily 
affected. Extreme poverty of soil is less apt to induce sterility ; 
but dwarfed plants of Trifolium 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. 81 
Mr. Scott, in the Botanic Gardens of Edinburgh, observed that 
Oncidium 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 fulgidum, for many years after 
its introduction, seeded freely; it then became sterile; now it is 
fertile 82 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 



78 'Swedish Acts,' vol. i., 1739, Chronicle,' 1848, pp. 253, 26S, and 
p. 3. Pallas makes the same remark mentions a few which seed. 

in his 'Travels '(Eng. translat.), vol. i. so ' Beitr'age zur Kenntniss der 

p. 292. Befruchtung,' 1844, s. 333. 

79 A. Kerner, 'Die Cultur der Al- 81 'Nova Acta Petrop.,' 1793, p. 
penpflanzen,' 1864, s. 139; Watson's 391. 

'Cybele Britannica,' vol. i. p. 131; 82 '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. XVILL 

resists the severest frosts, and T hare seen seeds gathered from pods 
which had been covered with snow during three weeks.* 3 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. 84 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 which they have been 
subjected. 

The liability of plants to be affected in then- 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 off and placed in 
water, and the pollen will be matured. Pollen, also, when 
once mature, may be kept for weeks or even months. 85 The female 
organs are more sensitive, for Gartner 8fi 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, 
a /'//"', when pulled up by its roots and placed in water, 
ri] ened it- seed. Flower-stems of several monocotyledonous plants 
when cut off and placed in water likewise produce seed. But in 
1 ] ^resume that the flowers had been already fertilised, 
for Herbert M found with the Crocus that the plants might be re- 
i <»r 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 e 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 



83 Dr. Herbert, ' Amaryllidaceae,' ' La Variability des Especes,' 18G8. p. 
p. 176. 155. 

84 Gartner, ' Beitr'dge zur Kennt- 86 ' Beitr'dge zur Kenntniss,' &c., s. 
niss,*& . - . >64. 252, 333. 

85 ' Gardener's Chronicle,' 18-14, p. 87 ' Journal of Hort. Soe.,' vol. ii., 
2l r . ; 1850, p. 470. Faivre gives a 1847, p. 83. 

good resume on this subject in his 



Chap. XYIII. 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 plains and on the mountains of India ; nevertheless, they all 
remain fully fertile. 

Contabescence. — Gartner has designated by this term a peculiar 
condition of the anthers in certain plants, in which they are shri- 
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/ 8 in Iris discussion on this subject, has 
shovrn 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 aff 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 become 
precocious in their development. The cause of this affection is 
doubtful, and is different in different 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 changed 
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 j^lants of 
Dianthus and Yerbascum, found wild by Wieginann, 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 ean 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 



8S ' Beitrage zur Kenntniss,' &c, s. setzung,' s. 57. Herbert, ' Amarylli- 
117 et seq. ; Kolreuter, 'Zweite Fort- daceas,' p. 355. Wiegmann, ' Uebex 
setzung,' s. 10, 121 ; ' Dritte Fort- die Bastarderzeugung,' s. 27. 



150 STERILITY. Chap. XVIII 

the female organs struck with sterility, whilst the male organs 
remain perfect. Diavihus jajonkus, a Passifiora, and Nicotiana, 
have been described by Gartner b9 as being in this unusual con- 
dition. 

Monstrosities as a cause of sterility. — Great deviations 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, 90 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. 91 Species of Primul i 
in which the calyx is brightly coloured are said 92 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. 93 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 Saxifrage/, geum, in which a series 
of adventitious carpels, bearing ovules on their margins, had been 
developed between the stamens and the normal carpels. 94 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 
in" jut, when artificially fertilised with their own 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, 95 are sometimes 
barren and sometimes fertile ; whilst 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 



89 ( Bastarderzeugung,' s. 356. p. 483. Prof. Harvey, on the autho- 

90 'Teoria delta Riproduzione,' rity of Mr. Andrews, who discovered 
1816, p. 84; ' Traite du Citrus,' 1811, the plant, informed me that this 
p. 67. monstrosity could be propagated by 

91 Mr. C. W. Crocker, in 'Card. seed. With respect to the poppy, see 
Chronicle,' 1861, p. 1092. Prof. Goeppert, as quoted in 'Journal 

92 Yerlot, ' Des Varietes,' 1865, of Horticulture,' Ju.lv 1st, 1863, p. 
P . 80. 171. 

93 Verlot, ibid., p. 88. 95 'Comptes Rendos,' Dec. 19th, 

94 Prof. Allman, Brit. Assoc, 1864, p. 1039. 
j noted in the ' Phytologist,' vol. ii. 



Chap. XVIII. DOUBLE FLOWERS. 151 

flower of another variety; 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 Floiuers. — 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 completely 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 Composite bear what are 
called double flowers by the abnormal development of the corolla of 
their central florets. Doubleness is sometimes connected with 
prolifi cation, 96 or the continued growth of the axis of the flower. 
Doubleness is strongly inherited. No one has produced, as Lindley 
remarks, 97 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. 98 
Long-continued cultivation in rich soil seems to be the commonest 
exciting cause. A double narcissus and a double Anthemis nobilis, 
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, 100 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 



96 'Gardener's Chronicle,' 1866, p. can Journ. of Science,' vol. xxiii. p. 
681. 47 ; and Verlot, ' Des Vaiietes,' 1865, 

97 < Theory of Horticulture,' p. 333. p. 84. 

93 Mr. Fairweather, in ' Transact. ,J ' J Lindley's ' Theory of Horticul- 

Hort. Soc.,' vol. iii. p. 406 : Bosse, ture,' p. 3 3. 

quoted by Bronn, 'Geschichte der 10 ° ' Gardener's Chronicle,' 1865. p. 

Natur,' B. ii. s. 77. On the effects of 626 ; 1866, pp. 290, 730 ; -and Verlot, 

the removal of the anthers, see Mr. ' Des Varietes,' p. 75. 
Leitner, in Siliiman's ' North Ameri- 



152 STERILITY FKOM THE DEVELOPMENT Chap. XVIIL 

the antagonistic state, commonly arises from a plethoric condition. 
On the other hand, extremely poor soil sometimes, though rarely, 
appears to cause doubleness : I formerly described 101 some completely 
double, bud-like, flowers produced in large numbers by stunted 
wild plants of Gentiana 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, 
sEsculus pavia, and StaphyJed), growing under Tery unfavourable 
conditions. Professor Lehmann l0 ' 2 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 perform their proper functions, they either become 
developed into petals, or additional petals are formed. This 
view has lately been supported by Mr. Laxton, 103 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 pine-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. 104 Most horticulturists 
look at the great size and anomalous development of the fruit as the 
cause, and sterility as the result ; but the opposite view, as we shall 
presently see, is more probable. 

Sterility from i ssive development of tlie 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 



101 ' Gardener's Chronicle,' 1843, p. 'Races of Man;' Gallesio, 'Teoria 
628. In this article I suggested the dellaRiproduzione,'18I6,pp.l0l-110. 

theory above given on the doubleness Meyen (' Reise um Erde,' Th. ii. s. 

o*.' flowers. This view is adopted by 214) states that at Manilla one 

Carriere, 'Production et Fix. des variety of the banana is full of seeds: 

Varietcs.' 1865, p. 67. and Chamisso (Hooker's ' Eot. Misc.,' 

102 Quoted by Gartner, ' Bastarder- vol. i. p. 310) describes a variety of 
gengung,' s. 567. the bread-fruit in the Mariana islands 

103 ' Gardener's Chronicle,' 1866, p. with small fruit, containing seeds 
901. which are frequentlv perfect. Burnes. 

104 Lindley, ' Theory of Horticul- in his ' Travels in Bokhara,' remarks 
ture.' pp. 170-1 79 ; Godron, • De l'Es- on the pomegranate seeding in Mazen* 
pece,' torn. ii. p. 106; Pickering, deran, as a remarkable peculiarity. 



Chap. XVIII. OF THE ORGANS OF VEGETATION. 153 

mutilated. 105 So it is with hybrids; for instance, Prof. Lecoq 106 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 vigorously 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. 107 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 {Convolvulus batatas) in China never, as far as he has seen, 
yields seed. Dr. Eoyle remarks 108 that in India the Agave 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. 109 That many plants when thus propagated are sterile 
there 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 

io5 Ingledew, in ' Transact, of Agri- several species indigenous in Mauri- 
cult, and Hort. Soc. of India,' vol. ii. tius. 

106 'De la Fecondation,' 1862, p. 1(/8 'Transact. Linn. Soc.,' vol. xvii. 
S08, p. 563. 

107 Hooker's 'Bot. Misc.,' vol. i. p. 10D Godron, ' De l'Espece,' torn. ii. 
99; Gallesio, 'Teoria della Ripro- p. 106 ; Herbert on Crocus, in ' Jour- 
duzione,'p. 110. Dr. J. de Cordernoy, nal of Hort. Soc.,' vol. i., 1816, p. 
in 'Transact, of the R. Soc. of Mauri- 254: Dr. Wight, from what he has 
tius' (new series), vol. vi. 1873, pp. seen in India, believes in this view ; 
60-67, gives a lai ge number of cases ' Madras Journal of Lit. and Science,' 
of plants which never seed, including vol. iv., 1836, p. 81. 



154 STERILITY. Chap. XYIII. 

ascend mountains beyond the height at which they can produce 
seed. 110 Certain species of Poa and Festuca, when growing on 
mountain-pastures, propagate themselves, as I hear from Mr. 
Bentham. almost exclusively by bulblets. Kami gives a more curious 
instance m 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 Russia, 
but flowers and fruits only in the southern provinces. The Acorus 
us 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. 112 The Hypericum calycinum, 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. The Lysimachia nummu- 
lary, which is furnished with long runners, so seldom produces 
seed-capsules, that Prof. Decaisne, 113 who lias especially attended to 
this plant, has never seen it in fruit. The Curex riyvla often fails 
to perfect its seed in Scotland, Lapland. Greenland, Germany, and 
New Hampshire in the United States. 114 The periwinkle (Vifica 
minor'), which spreads largely by runners, is said scarcely ever to 
produce fruit in England ; 1K> but this plant requires insect-aid for 
it> fertilisation, and the proper insects may be absent or rare. The 
• ' ./ grundiflora 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. 116 The horse- 
radish {Cockle iri 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 Ranunculus ficaria 
rarely bears seed in England. France, or Switzerland; but in 1863 
I observed seeds on several plants growing near my house. 117 Other 



110 Wahlenberg specifies eiirht ZooL, torn. iv. p. 280. Prof. Decaisne 

speries in this state on the Lapland rttVrs also to analogous cases with 

Alps: see Appendix to Linmr-us' ' Tour musses and lichens near Paris, 
in Lapland,' translated by Sir J. L. m Mr. Tuckermann, in Silliman's 

Smith, vol. ii. pp. 274-280. 'American Journal of Science,' vol. 

in 'Travels in North America.' xiv. p. 1. 
Eng. translate, vol. iii. p. 175. 115 Sir J. E. Smith, ' English Flora,' 

■■-' With respect to the ivy and vol. i. p. 

L>r. Bromtield in the • Phy- U6 G. Pianchon. 'Flora de Mont- 

I. iii. p. 376. Also Lin 1- pellier,' 18*34-. p. 20. 

lev and Vaucher on the Acorus, and 1K On the non-production of seeds 

Lspary as be! in England, see Mr. Crocker, in ' Gar- 

113 'Anna! ScXat.,' -. dener's Weekly Magazine,' 1852, p. 



Chap. XVIII. STERILITY. 155 

cases analogous with the foregoing could be given; for instance, 
some kinds of mosses and lichens have never been seen to fructify in 
Prance. 

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 tho 
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 development of 
fruit, seldom supervenes at once. An incipient tendency is 
observed, and continued selection completes the result. The 
view which seems the most probable, and wdiich 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 Gartner 118 affirms, 



70;Vaucher, 'Hist. Phys. Plantes phar,'" Abhand. Naturw. Gesellsch. zu 

d'Europe,' torn. i. p. 33 ; Lecoq, ' Geo- Halle, 5 B. xi. 1870, p. 40, 78. 

graph. Bot. d'Europe,' torn. iv. p. 118 ' Bastarderzeugung,' s. 50S 

466 ; Dr. D. Clos, in ' Annal. des Sc. Kolreuter (Dritte Fortsetzung, s. 

Nat.,' 3rd series, Bot., torn, xvii., 73, 87, 119) also shows that wher. 

1852, p. 129: this latter author refers two species, one single and the other 

to other analogous cases. See more double, are crossed, the hybrids are 

especially on this plant, and on other apt to be extremely double, 
allied cases, Prof. Caspary, " Die Nu- 



] OQ 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, 119 first become double. Again, Gart- 
ner 120 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 CucurbitaceaB ; so 
that the production of fruit by plants rendered sterile through 
uiy cause is intelligible. Kolreuter has also expressed his 
unbounded astonishment at the size and development of the 
tubers in certain hybrids; and all experimentalists 121 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 they 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, 
ami in some cases largely-developed organs of vegetation, &c, 
are the indirect results — these results having been in most 
largely increased through continued selection by man. 

119 'Teoria della RiproJuzione 120 ' Bastavderzeugung,' s. 573. 

V eg.,' 18ld, p. 73. m Ibid., s. bll. 



Chat. XIX. SUMMARY OF THE FOUR LAST CHAPTERS. 157 



CHAPTER XIX. 

SUMMARY OF THE FOUR LAST CHAPTERS, WITH REMARKS ON 
HYBRIDISM. 

DX 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 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 CONFIXED 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 SFECIES AND 
CROSSED VARIETIES — CONCLUSION. 

It was shown in the fifteenth chapter that when 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 appeared. 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, mongrels have retained a uniform character from their 
first production. 

When two varieties are allowed to cross freely, and one is 

29 



158 SUMMAKT OF THE Chap. XIX. 

much more numerous 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 possession of the same tribe, their crossing 
will not have influenced, in so great a degree as Ins 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 plan Is. It eliminates the tendency to sterility 
which 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, pig-. &<?., are almost 
certainly descended from aboriginally distinct stocks, and as 
these races are now fully fertile together, or at least incom- 
parably 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 healthy ; and such plants can be stimulated to fertility 
only by being crossed with other individuals of the sanie 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 
bleeders, especially of those who have reared many animals 
of quickly 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 aie 
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, 1 and, not long afterwards, that sagacious 

1 ' Transactions Phil. Soc.,' 1799, observer failed to understand the full 
p. 202. For Kolreuter, see ' Mem. de meaning of the structure of the 
l'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 SOIMAftY OF THE Chap. XIX. 

observer Kolreuter, after stowing how well the Malvaceae 
are adapted for crossing, asks, "an id aliquid in recessu 
habeat, quod hujuscemodi flores nnnqnani proprio suo pul- 
vere, sed semper eo aliarum sua3 speciei impregnentur, nierito 
quaeritur? Certe natura nil facit frustra." 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 mure 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. AVith 
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 supply 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. CiiAr. XIX. 

diminishing, generally adds to the fertility of the 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 

Nevertheless, 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 
.led 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 - - : and this 

- to make a broad and impassable barrier between 
domestic varieties and natural species. Cut. as I will now 
attempt to show, the distinction is not so great and over- 
whelmingly important as it at first appears. 

On the -D/; Fertility between Varieties and Species icltcn 

This work is not the proper place for fully treating the 
suhjeet of hybridism, and I have already given in my ' Origin 
of Species ' a moderately full abstract. I will here merely 
enumerate the general conclusions which may be relied on, 
and which bear on our present point. 

Firstly, tha laws governing the production of hybrids are 



Chat. XIX. HYBEIDISM. 103 

identical, or nearly identical, in the animal and vegetablo 
kingdoms. 

Secondly, the sterility of distinct species when first united, 
and that of their hybrid 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. Hybrids 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 those 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 with 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. Waklverwandtschaft 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 
-\ stematic position. 

Sixthly, the sterility of species when firot crossed, and that 
of hybrids, may possibly depend toa certain extent on distinct 
- 8. 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 
ejrsr, or Be <\ of the mother-form: and as Ave 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 .^ee 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. 

ntUy, hybrids and mongrels present, with the one great 



Chap. XIX. HYBRIDISM. 165 

exception of fertility, the most striking accordance in all othei 
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 
trimorphic 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. Now 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. 2 
. The infertility which may be observed in various dimorphic 

2 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 oi 

were published in the ' Journal of the Species.' 



166 HYBRIDISM. Chat. XIX. 

and trimorphic plants, when illegitimately fertilised, that is, 
by pollen taken from stamens not corresponding in height 
with the pistil, differs much, in degree, up 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 prepotent 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 

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 
two species, there is occasionally a 
great difference in the result, so the same thing occurs with 
trimorphic plants; for instance, the mid-styled form of 
Lythrum salicaria could 1 e illegitimately fertilised with the 
greatest ease by pollen from the longer stamens of the short- 
styled form, and 3 ielded nan. ut the short-styled form 

did not yield a single & ed when fertilised by the longer 
stamens of the mid-styled form. 

In all these respects the forms of the same undoubted 

s, 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,. 
from several illegitimate unions. The chief result is 
that these illegitimate plants, as they may be called, are not 
fully fertile. It is possible to raise from dimorphic S] 
both long-styled and short-styled illegitimate plants, and 

trimorphic plants all three illegitimate forms. 1'hese 



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 yield as many seeds as did their parents when legiti- 
mately fertilised. But such is not the case ; they are all 
infei tile, 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 
when crossed inter se, and it is well known how sterile these 
latter generally are. When, on the other hand, a hybrid is 
crossed with 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 species 
by the improper union of certain forms, whilst ordinary 
hybrids are produced from an improper union between so- 
called distinct species. We have already 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 
Lytlirum scdicaria, and that he determioed to try by crossing 



168 HYBRIDISM. Chap. XIX. 

whether they were specifically distinct. He would find that 
they yielded only 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 
hybridised 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 ihe infertility of illegitimate unions with that 
of their illegitimate offspring, and we are led to extend the 
same view to first i ss - ind hybrids; thirdly, because we 
find, and this seems to me of especial importance, that two or 
three forms of the same e ty exist and may differ 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 ( fcween 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 progen} r , 
Is exclusively on the nature of their sexual elements, 
and not on any difference in their structure or general am- 



Chap. XIX. HYBRIDISM. 169 

stitution. We are also led to this same conclusion by con- 
sidering reciprocal crosses, in which the male of one species 
cannot he 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 we admit that the 
structural differences 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 (Mascari 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, which when 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 
Wi/iild 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 < i itli<-iilti«-s will be found to lie in the existence 
of many graduated steps from slightly 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 ; fur 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 
• v which this first degree of sterility could be increased 
through natural selection to that higher degree which is 
common to so many s] ad which is universal with 

species which have been differentiated to a generic or family 
rank, will rind 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 i> 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 7 



Chap. XIX. HYBKIDISM. 1.7 1 

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. 
With 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 
Kblreuter 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 HTBRIDISM, Chap. XIX. 

exposed; and tin's 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 he 
grafted on each other, or on a third species, differs much, and 
i& of no advantage to these trees, but is incidental on struc- 
tural or functional differences in their woody tissues. AVe 
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 Passijiora 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 fertilised by the pollen 
of a distinct species — and lastly the cases of individual 
sticated 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 
vi plants, domesticated varieties, such as those of the dog, fowl, 
pig< m in,fleveral fruit-trees, and culinary vegetables, which differ 
l'i . »m 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 
si rile ? We 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 sterility, 
that we have very good grounds for admitting the directly 
opposite doctrine of Pallas, namely, that such conditions 



Chap. XIX. HYBEIDISM. 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. "With 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 ctate 
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 (Anagallis 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 the 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 difference 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 
spe :-ies, but with varieties until lately no such difference had 
been observed. Here we have various physiological 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 system. Why, then, should these latter differ- 
ences, however serviceable they may indirectly be in keeping 



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. 

SELECTION A DIFFICTLT ART — METHODICAL, UNCONSCIOUS, AND NATURAL 
SELECTION — RESULTS OF METHODICAL SELECTION CARE TAKEN IN SE- 
LECTION SELECTION -SVTTH PLANTS SELECTION CARRIED ON BY THE 

ANCIENTS AND BY SEMI-CIVILISED PEOPLE — ENTMPORTANT CHARACTERS 

OFTEN ATTENDED TO — ENCONSCIOES SELECTION AS CIRCUMSTANCES 

SLOWLY CHANGE, SO HAVE OCR DOMESTICATED ANIMALS CHANGED 
THROUGH THE ACTION OF UNCONSCIOUS SELECTION — INFLUENCE OF 
DIFFERENT BREEDERS ON THE SAME SUB-VARIETY — PLANTS AS AFFECTED 
BY UNCONSCIOUS SELECTION — EFFECTS OF SELECTION AS SHOWN BY THE 
GREAT AMOUNT OF DIFFERENCE IN THE PARTS MOST VALUED BY MAN. 

The power of Selection, whether exercised by 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. 



Uhaf. A A. 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 any 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 
eyes 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 as he has not a prede- 
termined purpose to improve the breed, he may be said to be 
selecting unconsciously. 1 Lastly, we have Natural selection, 
1 The term unconscious selection has been objected to as a contradiction \ 



178 SELECTION. Chap. XX. 

which implies that the individuals 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. 

Methodical Selection. — What man has effected within recent 
times in England hy 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, 2 the 
principle of selection is " that which enables the agricul- 
turist, not only to modify the character of his fiock, but to 
change it altogether." A great breeder of Shorthorns 3 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 4 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 2 'On Sheep,' 1838, p. 60. 

on this head bv Prof. Huxley ('Nat. 3 Mr. J. Wright on Shorthorh 

Hist. Review,' Oct. 1864, p. 578), who Cattle, in ' Journal of Royal Agricuit 

remarks that when the wind heaps Sue.,' vol. vii. pp. 208. 21 39. 

up sand-dune3 it sifts and uncon- i H. D. Richards-m ' On Pigs,' 1847 

sciously selects from the gravel on the p. 44, 

beach grains of sand of equal size. 






Ciiap. 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 futurity. Lord 
Spencer's skill and judgment were well known; and he 
writes, 5 " 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 New Leicester 
sheep, effected by Bakewell and his successors, says, " It 
would seem as if they had first drawn a perfect form, and 
then given it life." Youatt 6 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) rules 
were established, and a standard of perfection was fixed ac- 
cording to which the London fanciers tried to breed the 
several sub- varieties. 7 A great winner of prizes at the Pigeon - 
shows, 8 in describing the short-faced Almond Tumbler, says, 
" 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; bat 
" as I think the goldfinch-beak the handsomest, I would advice 
" the inexperienced fancier to get the head of a goldfinch, and 
" keep it by him for his observation." Wonderfully different 

5 < Journal of Royal Agricult. Sec.,' vol. viii., 1835, p. 618. 
r<-l. i. p. 24. & ' A treatise on the Art of Breed. 

' On Sheep,' pp. 520, 319. ing the Almond Tumbler,' 1851, p. 0. 

1 Loudon's ; II ag. of Nat. Hist.,' 



180 SELECTION. Chap. XX. 

as are tlie beaks of the rock pigeon and goldfinch, the end 
has undoubtedly "been nearly gained, as far as external shape 
and proportions are concerned. 

Not only should our animals be examined with the greatest 
care whilst alive, but. as Anderson remarks. 9 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. 1 " 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, 11 speaking of Cocb in-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-flavoured, 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 12 " 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 year to year to furnish a class of 
" bulls which are steadily improving the general breed of the 
" district.' 5 The rearing and letting of choice rams has 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 ^heep to an extreme point. 13 So impor- 
"tant is the proper selection of breeding animals considered, 
" that the best flock-masters do not trust to their own judg- 
" meut or to that of their shepherds, but employ persons called 
" ; sheep-classifiers,' who make it their special business to 
11 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 

9 ' Recreations in Agriculture,' vol. _As;ricult. Soc' quoted in 'Gard. 

ii. p. 409. Chronicle,' 1844, p. 29. 

40 Youatt on Cattle, pp. 191, 227. 13 Simmonds, quoted in 'Gard. 

11 Ferguson, * Prize Poultry-,' 1854, Chronicle,' 1855, p. 637. And foi 

. 8. the second quotation, see Youatt on 

u "Vilson, in 'Transact, Highland Sheep, p. 171. 



Chap. XX. METHODICAL SELECTION. 18] 

" the lambs are weaned, each in his turn is placed npon a 
4i 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 
s 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 14 
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. 15 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. 16 

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." 17 Mr. Bult, 
whose pouter-pigeons won so many prizes, and were exported 
to North America under the charge of a man sent on purpose, 

u Robinet, < Vers a Soie,' 1848, p. 16 M. Simon, in 'Bull.de la Soc. 

271. d'Aeclimat.,' torn, ix., 1862, p. 221. 

15 Quatrefages, ' Les Maladies du 17 ' The Poultry Chronicle,' vol. i., 

Ver a Soie,' 1859, p. 101. 1854, p. 607. 

30 



182 SELECTION, Chap. XX. 

told me that lie always deliberated for several days before he 
matched each pair. Hence we can understand the advice of 
an eminent fancier, who writes, 13 " 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 by getting nothing." We thus see 
that breeding even fancy 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. Corringham remarks, 19 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, 

18 J. M. Eaton. 'A Treatise on 1851, p, 11. 
Fancy Pigeons,' 1852, p. xiv., and 19 'Journal Royal Agrieultura' 1 

A Treatise on the Alnionl Tumbler,' Soc.,' vol. vi. p. 22. 



Chap. XX. METHODICAL SELECTION. 183 

and out of fifty-seven pens lately (1860) exhibited at the 
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," says another fancier, " of which he may be 
justly proud." 20 . 

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 21 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., 21 Isid. Geoffroy St.-Hilaire, ' Hist 

1855, p. 596. Nat. Gen.,' torn. iii. p. 254. 



L84 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 22 how " many a patient hour was devoted," 
whilst he was young, to the detection of differences in peas 
intended for seed. Mr. Barnet 23 remarks that the old scarlet 
American strawberry 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. 
AYith the Cineraria, Mr. Glenny 2i '"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 Rev. W. Williamson,- 5 after sowing during several years 

"'Gardener's Chron.,' 1850. p. « « Journal of Horticulture/ 18G2, 

198. p. 369. 

23 '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 perseverance in the 
same course obtained several varieties with six or seven rows 
of petals. The single Scotch rose was doubled, and yielded 
eight good varieties in nine or ten years. 26 The Canterbury 
bell (Campanula medium) was doubled by careful selection in 
four generations. 27 In four years Mr. Buckman, 28 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. 29 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. 30 

S<. lection by Ancient and Semi-civilised People. 

In attributing so much importance to the selection ot 
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- 

26 'Transact. Hort. Soc.,' vol. iv. p. vi. p. 96; Mr. Barnes, in « Gard. 
285. Chronicle,' 1844, p. 476. 

27 Rev. W. Bromehead, in 'Gard. so Godron, 'De l'Espece,' 1859, 
Chronicle,' 1857, p. 550. torn. ii. p. 69; 'Gard. Chronicle,' 

28 'Gard. Chronicle,' 1862, p. 721. 1854, p. 258. 

29 Dr. Anderson, in ' The Bee,' vol. 



186 SELECTION. Chap. XX. 

sionally carried on, "by a few of the inhabitants 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, 31 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 haye 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, 32 so that at this early period other nations must have 
crossed the horse and ass. It is said 33 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 iEneas' 
horses as bred from mares which were put to the steeds of 
Laomedon. Plato, in his ' Eepublic,' says to Glaucus, " I see 
that }*ou 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 always some which are 
superior to the rest ? " To which Glaucus answers in the 
-affirmative. 34 Alexander the Great selected the finest Indian 
cattle to send to Macedonia to improve the breed. 35 Aoccord- 
ing to Pliny, 36 King Pyrrhus had an especially valuable 
breed of oxen : and he did nut 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, carefully 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 progeny; — to select sheep of the purest white, and tj 
examine if their tongues are swarthy. AVe have seen that the 

31 On Sheep, p. 18. =» Dr. Dally, fcrwurl&ied in * Anthro- 

3 - Volz, ' Beitrage zur Kulturge- pological Review,' May 1864, p. 101. 

ichichte,' 1852, s. 47. a Volz, 'Beitrage,"' &c, 1852, s, 

* 3 Mitford's 'History of Greece.' 80. 

vol i. p. 73. aj 'History of the World,' ch. 45. 



Chap. XX. BY THE ANCIENTS. 187 

Romans kept pedigrees of their pigeons, and this would 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, with 
" large heads, with upright and bright-red combs. Those 
" are believed to be the best bred which have five toes." 37 
According to Tacitus, the Celts attended to the races of their 
domestic animals ; and Ca?sar states that they paid high 
prices to merchants for fine imported horses. 38 In regard to 
plants, Yirgil 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." 39 

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. 40 Even .in a country so 
little civilised as Ireland during the ninth century, it would 
appear from some ancient verses, 41 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 Aengus. 

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 
hoi ses. King John imported " one hundred chosen stallions 
from Flanders." 42 On June 16th, 1305, the Prince of Wales 

37 'Gardener's Chronicle,' 1848, p. 41 Sir W. Wilde, an 'Essay on Un- 
323. ^ manufactured Animal .Remains,' &c, 

38 Reynier, ' De l'Economie des 1860, p. 11. 

Celtes,' 1818, pp. 487, 503. « CoL Hamilton Smith, 'Nat. 

39 Le Couteur on Wheat, p. 15. Library,' vol. xii., Horses, pp. 135, 
i0 Michel; ' Des Haras,' 1861, p, 84. 140. 



1SS SELECTION. Chap. XX 

wrote to tlie Archbishop of Canterbury, begging for the loan 
of any choice stallion, and promising its return at the end of 
the season. 43 There are numerous records at ancient periods 
in English history of the importation of choice animals of 
various 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. 44 
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. 45 

The Emperor Akbar Khan before the year 1600 is said to 
have " wonderfully improved " his pigeons by crossing the 
breeds ; and this necessarily 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 46 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, 

43 Michel. ; Des Haras.' p. 90. tion on the ancient selection of sheep : 

" Mr. Baker, ' History of the and is my authority for rams nut 

Horse,' ' Veterinary.' vol. xiii. p. 423. being killed young in England. 

45 M. l'Abbe Carlier, in 'Journal 4C 'Gardener's Chronicle,' 1843, p 

de Physique.' vol. xxiv., 17S4-. p. 181 ; 389. 

this memoir contains much informa- 



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." 47 

In the great work on China published in the last century 
by the Jesuits, and which is chiefly compiled from ancient 
Chinese encyclopedias, 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 
principles were applied by the Chinese to various plants and 
fruit-trees. 43 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 period in a field by the Em- 
peror Khang-hi, was saved and cultivated in his garden, and 
has since become valuable from being the only kind which 
will grow north of the Great Wall. 49 Even with flowers, 
the tree pgeony (P. moutan) has been cultivated, according to 
Chinese traditions, for 1400 years; between 200 and 300 
varieties have been raised, which are cherished like tulips 
formerly were by the Dutch. 50 

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, 51 however, describes in Columbia a naked race 
of cattle, which are not allowed to increase, on account of 
their delicate constitution. According to Azara 52 horses are 
often born in Paraguay with curly hair ; but, as the natives 

47 ' Communications to Board of to Khang-hi, see Hue's ' Chinese Em- 
Agriculture,' quoted in Dr. Darwin's pire,' p. 311. 

I'hytologia,' 1800, p. 451. 50 Anderson, in ' Linn. Transact.,' 

48 ' Memoire sur les Chinois,' 1786, vol. xii. p. 253. 

torn. xi. p. 55 ; torn. v. p. 507. 51 ' Mem. de l'Acad.' (divers sa- 

49 'Recherches sur l'Agriculture vants), torn, vi., 1835, p. 333. 

des Chinois,' par L. D'Hervey Saint- 52 ' Des Quadruples du Paraguay,' 

Denys, 1850, p. 229. With respect 1801, torn. ii. pp. 333, 371. 



190 SELECTION. Chai\ XX. 

do not like them, they 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. The pedigrees are handed down, and many a droine- 
" dary can boast a genealogy far longer than the descendants 
" of the Darley Arabian." 53 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. 5 " 1 

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 Canidae, 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, in the 

53 < The Great Sahara,' bv the Rev. burg/ 1777. p. 249. Moorcroft and 
H. B. Tristram, 1860, p. 238. Tvebeck, « Travels in the Himalayan 

54 Pallas, 'Act. Acad. St. Peters- Provinces,' 1841. 



Chap. XX. BY SEMI-CIVILISED PEOPLE. 191 

Baine manner as at the present clay the natives of Java some- 
times drive their cattle into the forests to cross with the wild 
Banteng (Bos sondaicus). 55 In Northern Siberia, among the 
Ostyaks, the dogs vary in markings in different districts, but 
in each place they are spotted black and white in a remark- 
ably uniform manner ; 5b 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 E. Schomburgk informs me, 57 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 
care 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. 58 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 

55 Quoted from Raffles, in the graph. Soc.,' vol. xiii. part i. p. 65. 
'Indian Field,' 1859, p. 196: for 58 Livingstone's 'First Travels,' pp. 
Vano, see Pallas, ut supra. 191, 439, 565 ; see also ' Expedition to 

56 Erman's 'Travels in Siberia,' the Zambesi,' 1865, p. 495, for an 
Eng. translat., vol. i. p. 453. analogous case respecting a gooj 

& See also 'Journal of R. Geo- breed of goats. 



192 SELECTIOX. Chap. XX 

Darnaras 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 
44 beast of burden." 59 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. 60 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 destroyed as injurious. The wild Gnanacos and Yicunas 
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," were 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. 61 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, — tLc Guanaco 

59 Andersson's 'Travels in South lotf. 

Africa,' pp. 232, 318, 319. cl 'T^° N?tural Historj of De« 

60 Dr. Vavasseur, in 'Bull, de la Side,' 18.:<r p. 47 o\ 
Soc. d'Acclimat.,' torn, viii., 1861, p. 



Chap. XX OF TRIFLING CHARACTERS. 193 

and Yicuna, 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 
1heir propagation, adduces arguments 62 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, 63 " speaks of a hundred white cows with red ears 
1 being demanded as a compensation by the princes of North 
4i and South Wales. 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 

• 2 'Bull, de la Soc. d'Acclimat.,' torn, vii., 1860, p. 457. 63 'Cattle,' p. 48. 



194 SELECTION. Chap. 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 sprung up for her possession, and she realised a 
'■ considerable price." 64 With respect to sheep, the Chinese 
prefer rams without horns ; the Tartars prefer them with 
spirally wound horns, "because the hornless are thought to 
lose courage. 65 Some of the Damaras will not eat the flesh 
of hornless sheep. In regard to horses, at the end of the 
fifteenth century animals of the colour described as liari 
pomme were most valued in France. The Arabs have a 
proverb, ' ; Never buy a horse with four white feet, for he 
carries his shroud with him ; " C6 the Arabs also, as we have 
seen, 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." 6T 

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. 68 In Guiana, as 1 am informed by Sir E. 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 

64 Livingstone's Travels, p. 576; 66 F. Michel, ' Des Haras,' pp.47. 
Andersson, 'Lake Kgami,' 1356, p. 50. 

With respect to the sale in 67 Col. Hamilton Smith, Dogs, in 

Kafiraria, see 'Quarterly Review/ 'Sat. Lib.,' vol. x. p. 103. 

1860, p. 139. c8 Azara, ' Quadruples du Para- 

65 • Menioire sur les Chinois'(by the guay,' torn. ii. p. 324-. 
Jesuit;), 1786, 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." 69 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." 70 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 a.pplied 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." 71 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 difference between methodical and 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 
YIII.'s reign of all under-sized mares, are instances of a 
process the reverse of selection in the ordinary sense of the 

69 Sidney's edit, of Youatt, 1860, vol. ii. p. 182. 

pp. 24, 25. 71 Moll et Gayot, ' Du Bceuf,' 1860 

70 ' Rural Economy of Yorkshire,' p. 547. 



196 SELECTION. Chap. XX. 

word, but leading to the 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 army 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 fan tail" and was far from know- 
in g 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 modified, 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 methodically 
made the breeds exactly what they now are. As our horses 
became fleeter, and the country more cultivated and smoother, 
neuter fox-hounds were desired and produced, but probably 



Chap. XX UNCONSCIOUS SELECTION. 197 

without an}- 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 were 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. 

AVith 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?" 72 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, 73 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 by the Arabs during 
a still longer and earlier period, has ended in giving us the 
best breed of horses in the world. Macaulay 74 remarks, 

72 'The India Sporting Review,' 73 'The Horse,' p. 22. 

vol. ii. p. 181; 'The Stud Farm,' by 74 '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 Fen wick, 
" pronounced that the meanest hack ever imported from 
" Tangier would produce a finer progeny than 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 El anders 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, 75 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 difference 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; 3-et the differ- 
" ence between the sheep possessed by these two gentlemen is 
" so great, that they have the appearance of being quite 
" different varieties." T6 I have seen several analogous 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 apjDearance 

75 * Ueber Best'dndigkeit der Arten. 7G 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. 77 The Hereford cattle 
assumed their present well-marked character soon after the 
year 1769, through careful selection by Mr. Tomkins, 78 and 
the breed has lately split into two strains — one strain having 
a white face, and differing slightly, it is said, 79 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. 80 
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 
lias seen so much of the aborigines of Australia, informs me 

77 'Ueber Shorthorn Rindvieh,' 79 'Quarterly Review,' 1849, p. 
1857, s. 51, 392. 

78 Low, ' Domestkatei Animals,' 80 H. von Nathusius, ' Vorstudion 
1815, p. 363. .... Schweinesch'adel,' 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-" Different 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 tliere 
will have been some selection from an extremely remote 
period, but without any prefixed standard of excellence or 
thought of the future. AYe 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 wheat, 
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. sl The pears described 
by Pliny were evidently extremely inferior in quality to our 
present pears. AVe 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 Borne a representation of the 
melon ; and as the Koinans, 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,- 2 on comparing the flowers, 

81 See also Dr. Christ, in Riiti- 82 The passage is given, ' Bull. Soc. 

meyer's ' Pfahlbauten,' 1861, s. 22:5. 4'Acclimat.,' 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 steadily 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, 83 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 
4i did it." Mr. Paul, the well-known horticulturist, in writing 
of the same flower, 84 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. 85 A steady and gradual change has been 
noticed in many other flowers : thus an old florist, 86 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 

83 l Journal of Horticulture,' 1862, Floricult. Soc, in ' Gardener's Chro- 
p. 394. nicle,' 1843, p. 86. 

84 'Gardener's Chronicle,' 1857, 86 ' Journal of Horticulture,' Oct 
p. 85. 24th, 1805, p. 239. 

8i 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 15i5. s: 

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. "With 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. 88 

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. The 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 

87 Prescott's ' Hist, of Mexico,' vol. eleventh chapters I have given details 
ii. p. 61. on the potato ; and I can confirm 

88 Sagaret, 'Pomologie Physiolo- similar remarks with respect to the 
gi^ue,' 1830, p. 47 ; Gallesio, ; Teoria onion. I have also shown how far 
della Riproduzione,' 1816, p. 88 ; Xaudin concurs in regard to the 
Godron, 'De l'Espece,' 1859, torn. ii. varieties of the melon. 

pp. to, 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 
points. The varieties, however, of the Pois sans parchemin 
differ 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 gooseberry, 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 (whatever 
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 
supposing 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 continuall} 1 - 
augmented ; whilst other variations, excepting such as in- 
evitably appeared through correlation, were neglected and 



Chap. XX. SELECTION. 205 

lost. We may therefore infer that most plants might he 
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. 

With 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 clogs 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. 89 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 myself that this astonishing figure was an 
" accidental consequence of degeneration." 90 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 become 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. 

89 Godron, s De 1'Espece,' torn, ii, 90 'The Anthropological Treatises 

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

31 



206 SELECTION. Chap. X3. 

I vrill conclude this chapter by some reniaiks on an im- 
portant subject. With animals such as the giraffe, of which 
the whole structure is admirably 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. Xo 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 mouthfuls 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 natural 
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 Mmbs, all adapted 
for extreme fleetness, and for running down weak prey. 
Now, from what we see of the variability of animals, and 
fiom 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 91 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 

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

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

as given in the ' Belfast Northern Soc, in his sermon (Appendix, p. 83) 

Whig,' Nov. 19, 1S66. 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 minnte 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 practice; 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, 92 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 space 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 Yertebrata was originally acquired, 
for we know nothing about this organ in the first progenitors 
of the class. \Yith 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.' 93 

92 On the Vision of Fishes and p. 469. 
Amphibia, translated in 'Annals and 93 Sixth edition, 1872, p, 144. 

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



Chap. XXI. NATUEAL SELECTION. 209 



CHAPTER XXI. 

selection, continued. 

KAmtAL SELECTION AS AFFECTING DOMESTIC PRODUCTIONS CHARACTERS 

WHICH APPEAR OF TRIFLING VALUE OFTEN OP 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 MAN TO CARRY THE 
SELECTION OF EACH CHARACTER TO AN EXTREME POINT, LEADING TO 
DIVERGENCE OF CHARACTER, RARELY TO CONVERGENCE — CHARACTERS 
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 OP TIME IMPORTANT 
—MANNER IN WHICH DOMESTIC RACES HAVE ORIGINATED — SUMMARY. 

Natural Selection, or the 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 w r ild 
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 
u into less and less bulk : each generation was inferior to the 



210 SELECTION. Chap. XXI 

" preceding one ; and when the spring was severe, seldom 
" more than two-thirds of the lambs survived the ravages of 
" the storms." 1 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 Cir cassia, 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. 2 

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, yet firm neck, compact body, 
powerful and closely pressed wings, muscular thighs, strong 
beak niassive at the base, dense and sharp spurs set low on 
the legs for delivering the fatal blow, and its compact, glossy, 
and mail-like plumage serving as a defence. Kow 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, 3 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 
play with the carrier pigeon, for during their 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 every 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." 4 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 

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

325. Co' also Youatt on Cattle, pp. 3 'The Poultry Book,' 1866, p. 123. 

62. 69. Mr. Tegetmeier, 'The Homing or Car 

2 MM. Lherbette and De Quatre- rier Pigeon,' 1871, pp. 45-68. 
fages, in ' Bull. Soc. d'Acclimat.,' tcna. 4 Youatt on Sheep, p. 312. 



Chap. XXI. NATURAL SELECTION. 211 

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

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 
when 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 
importance ; 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. 

TVhen 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, 5 " 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 
5 ' Treatise on the Almond Tumbler,' 185.1. p. 33. 



212 SELECTION. Chap. XXL 

Niata cattle cannot so well effect from their upturned jaws 
and the shape of their lips ; consequently, if not attended to, 
they 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 eye wattles and 
great toj)knots. — 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 Laehnanihes 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, us 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 the 
inhabitants keep black sheep alone, because the Hypericum 
cri spurn abounds there; and this plant does not injure black 
sheep, but kills the wnite ones in about a fortnight's time. 6 

Complexion, and liability to certain diseases, are believed 

• Dr. Heus'mger, ' Woch-.'usohrift fur die Heilkunde,' Berlin, 184-C, s. 279. 



Chap. XXI. NA.TCBAL 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. 7 In North America plum-trees are liable to 
a disease which Downing 8 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 North 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. 9 
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. 10 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. 11 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. 12 White verbenas are especially liable 
i o mildew. 13 Near Malaga, during an early period of the vine- 

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

8 'The Fruit-trees of America,' u Quatrefages, ' Maladies Actuelles 
184-5, p. 270 : for peaches, p. 4-66. du Ver a Soie,' 1859, pp. 12, 214. 

9 'Proc. Royal Soc. of Arts and 12 ' Gardener's Chronicle,' 1851, p. 
Sciences of Mauritius/ 1852, p. 595. 

cxxxv. 13 'Journal of Horticulture/ 1862, 

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



2 1 4 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 colour and liability to 
disease was here observed. 14 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 15 the inhabitants 
do not like grey, white, or pale cattle, because they are much 
more troubled by various kinds of flies than the brown, red, 
or black cattle. An Albino negro, it has been remarked, 10 
was peculiarly sensitive to the bites of insects. In the West 
Indies 17 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 ; 1S 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 
verbena-s, 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 

14 ' Gardener's Chronicle,' 1S52, in West Indies,' ' Home and Col. 
pp. 435, 691. Library.' p. 100. 

15 Bechstein. 'Naturgesch. Deutseh- 18 Sidney's edit, of Yonatt on the 
lands,' 1801, B. i. s. 310. Pig, p. 24. I have given analogous 

18 Prichard, ' Phvs. Hist, of Man- facts in the case of mankind in my 
Vind.' 1851, vol. i. p. 224. « Descent of Man,' 2nd edit. p. 195. 

17 G. Lewis's ' Journal of Residence 



Chap. XXI. NATURAL SELECTION. 2 L5 

weather suits the blotched sorts, whilst it destroys the beau- 
tiful markings of some other kinds. 19 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. 20 

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. 31 
Prof. Gr. Jaeger 22 whilst fishing found four pigeons which 
had been killed by hawks, and all were white ; on another 
occasion he examined the eyrie 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, 23 
speaking of white rabbits kept in warrens in Bussia, 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 

19 ' 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 
respect to the heartsease, 'Gardener's 'Nat. Hist, of Ireland,' 184-9, vol. i. 
Chronicle,' 1863, p. 628. p. 22. 

20 ' Des Jacinthes, de lenr Culture,' 2 * ' In Sachen Darwin's contra 
1768, p. 53 : on wheat, ' Gardener's Wigand,' 1874, p. 70. 

Chronicle,' 1846, p. 653. 23 'Bull, de la Soc. d'Acclimat.,' 

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



216 SELECTION. Chap. XXI 

being so much like tliat of tlie leaves, or to the fruit always 
appearing from a distance unripe," is not so readily attacked 
by birds as otlier 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." 24 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 (Pyrus aucujjaria) 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 pois sans parchemin, are attacked by 
birds ' 25 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. 26 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.' 27 

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

2i -Transact. Hort. Soc,' vol. i. 2nd - 5 'Gardener's Chronicle,' J 343. p 

series, 1SJ5, p. 275. For raspberries, 806. 
see 'Gard. Chronicle,' 1855, p. 154, 26 Ibid., 1850, p. 732. 

Had 1863, p. 245. 2: Ibid., 1860, p. 956. 



Chap. XXL NATUKAL SELECTION. 217 

varieties are known to resist their attacks much better. 28 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 two-xhirds 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. 29 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 particular case has been re- 
corded in which aphides confined themselves to the W inter Nelis 
pear and touched no other kind in an extensive orchard. 30 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 
closely-related sub-varieties, descended from the same parent- 
tree ; yet there is good evidence 31 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 32 of the apple and 
thorn (Cratcegus oxyacantha) are more especially liable to 
be attacked. A striking instance of this was observed in 
Mr. Eivers's garden, in which two rows of a particular 

28 J. De Jonghe, in ' Gardener's 31 ' Journal of Horticulture,' Sept. 
Chronicle,' 1860, p. 120. 26th, 1865, p. 254; see other re- 

29 Downing, 'Fruit-trees of North ferences given in chap. x. 
America,' pp. 266, 501 : in regard to 3 Mr. Selby, in 'Mag. of Zoology 
the cherry, p. 198. and Botany 5 , Edinburgh, vol. ii., 1838 

*> ' Gardener's Chronicle,' 1849, p. p. 393. 
755. 



218 SELECTION. Chap. XXI 

variety of plum 33 had to "be carefully protected, as they 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. 34 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;" 33 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, 30 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 Fenton wheat is remarkably un- 
equal in height ; and a competent observer believes that 
this variety is highly productive, partly because the ears 
from being distributed at various heights above 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. 37 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, 3S in our wheat-fields, for, as 

33 The Reine Claude de Bavav. 35 Godron, ' De l'Espece/ torn. ii. p. 
1 Journal ot Horticulture,' Dec. 27, 98. 

1864-, p. 511. 3S 'Gardener's Chron..' I860. p. 73-2. 

34 Mr. Pusey, in 'Journal of R. 37 ' Gardener's Chronicle,' 1862, pp. 
Agricult. Soe./vol. vi. p. 179. For 820, 821. 

Swedish turnips, see ' Gard. Chron./ 38 'On the Varieties cf Wheat ,'p 

1847, p. 91. 59. 



Chap. XXI. FAVOURABLE CIRCUMSTANCES. 219 

formerly shown, no variety is quite 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. When 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. 39 

Facts in sufficient number have now been given showing 
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 depending on conditions, about which 
we are profoundly ignorant. 

Circumstances favourable to Selection by Man. 

The possibility of selection rests on variability, and this, as 
we shall see in the following 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, 40 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 

39 Mr. Hewitt and others, in ' Jour- 40 ' Encyclop. of Rural Sports,' p. 

nal of Hort.,' 1862. p. 773. 405. 



221/ SELECTION. 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." 41 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 barreu 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 : 42 it would 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 wonderfully-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 present 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 

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

47 Malingie-Nouel, Journal R. 



Chap. XXI. FAVOUKABLE 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 
varying 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 43 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 being 
raised, or some improvement effected on old kinds." 44 At 
Kew, as Mr. Beaton remarks, where many seedlings of common 
plants are raised, " you see new forms of Laburnums, Spmeas, 
and other shrubs." 45 So with animals : Marshall, 46 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 Rivers, 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 competitors breed largely, and 
keep the best." 47 

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 majority of the culinary and agri- 
cultural plants which have yielded numerous races are annuals 

43 'Gardener's Chronicle,' 1815, p. 368. 

273. 46 ' A Review of Reports,' 1808, p. 

44 'Journal of Horticulture,' 1862, 4-06. 

p. 157. 47 - Gardener's Chronicle,' 1853 ; p 

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



222 SELECTION. Chap. XXL 

or biennials, which 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 excejDtion 
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. Xo 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. Eussell, 
namely the sjoiegel-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. 48 
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 49 remarks, one kind 
alone exists there. The ass in England varies much in 

<8 Isidore Ge .: y Saint-Hilaire, 49 * Die Darwin'sche Theorie und das 

• Hist. Nat. Gen.,' torn. iii. p. 4y. • On Miirrationsgesetz der OrgauismeD,' 
the Cochineal Insect,' p. 46. 1868, p. 19. 



Chap. XXI. FAVOURABLE CIRCUMSTANCES. 223 

colour and size ; but as it is an animal of little value and 
bred by poor people, there lias 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. 1860) 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 Spain, 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 their 
exhibition. 50 

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. 51 
The common mignonette (Reseda odorata), from bearing in- 
conspicuous flowers, valued solely for their fragrance, " remains 
" in the same unimproved condition as when first intro- 
*' duced." 52 Our common forest-trees are very variable, as 
may be seen in every extensive nursery-ground ; but as they 
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, 53 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 so 

50 Capt. Marryat, quoted by Blyth 645. 

in 'Journ. Asiatic Soc. of Bengal,' 52 Mr. Abbey, in ' Journal of Horti- 

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

51 Mr. Oxley, 'Journal of the 53 'On Naval Timber,' 1831, p. 
Indian Archipelajo,' vol. ii., 1848, p, 107. 



2'1± SELECTION. Chap. XXI. 

strong a tendency to vary as is general!}' 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 propagated. 
Let a plant which is now grown in a botanic garden, or any 
a immon 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 prevails. 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. 54 

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 night and selected. 
Thus, with short-faced tumbler-pigeons, the shortness 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 difficulty of breed- 
ing them up to the highest standard of excellence. This 
subject has been discussed by fanciers, 05 and the greater 

5i Mr. Baily, in 'The Poultry Chro- 5i 'Cottage Gardener,' 1855, De- 

nicie,' vol. ii., 1854, p. 150. Also cember, p. 171; 1656. January, 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. Nathusius 
makes 56 a similar remark when discussing the less uniform 
character of improved Shorthorn cattle and of the English 
fiorse, 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 we 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. 

Asa consequence of continued variability, and more espe- 
cially of reversion, 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." 57 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 

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

47 'The Veterinary,' vol. xiii. p. 



22G 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 he transmitted, hut 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 Man to carry the practice 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 possible, 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, always 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, i; What fanciers intend doing with 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." 58 

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

58 J. M. Eaton. ' A Treatise on Mr. Brent, in ' Cottage GwleneT, 
Fancv Pigeons,' p. 82 ; Ferguson, on Oct. 18u0. p. 13. 
Rare and Prize Poultry,' p. 162 ; 



Chap, XXI. CARRIED TO AX EXTREME. 227 

races. We can thus see how 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, 59 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. 60 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 hybrids 
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 

39 ' Die Racen des Sohweines,' 1860, head by M. de Quatrefages, ' Unite de 
b. 48. l'Espfcce Humaine,' 1861, p. 119. 

'' v See some good remarks on this 



228 SELECTION. Chap. XXI. 

horticulturists : if a gardener observes one or two additional 
petals in a flower, lie 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." 61 Mr. Shirreff, who has 
been highly successful in raising new lands of wheat, remarks, 
" A good variety may safely be regarded as the forerunner of 
a better one." a2 A great rose-grower, Mr. Eivers, has made 
the same remark with respect to roses. Sageret, 63 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 way 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 positively 
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. 64 

61 Verlot, ' Des Varietes,' 1835, p. * 3 ' Pornologie Physiolog.,' 1830, p. 

9-k 106. 

82 Mr. Patrick Shirreff, in 'Gard. 6i Vouatt on Sheep, p. 521. 
Chronicle/ 1858, p. 771. 



Chap. XXL 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. 65 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, 66 " 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, 67 " it must not be 
concealed that we are far from the extreme limits at which 
we may arrive." 

IS^o 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, 68 the 
question that interests us, " is not whether indefinite and un- 
" limited change in any or all directions is possible, but 
" whether such differences 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 

65 See also Stonehenge, 'British Chron.,' 1858, p. 173. 
Rural Sports,' edition of 1871, p. 384. 68 } Contributions to the Theory of 

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

Tumbler,' p. i. p. 292. 

07 M. J. de Jonghe, in l Gard. 

82 



230 SELECTION. Chap. XXI 

doubt that many parts of the organisation, to which 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 day, 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 aiiimals 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-tongue. 69 

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 
6 . 9 Max Milller, 'Science of Language,' 1861, p. 223. 



Chap. XXI. SELECTION. 231 

stronger degree, all that we do not know, 70 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 
closely 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 always 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, 71 
" we know how quickly the memory of. such events is 
effaced." 

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 
j)robably 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. 72 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 

70 Youatt on Cattle, pp. 116, 128.. 72 Volz, 'Beitrage zur Kulturge- 

71 ' Doraesticntei Animals,' p. 188. schichte,' 1852, s. 99 et passim. 



232 SELECTION. Cuap. 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," 73 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 different 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 competitors and enemies, undei 

73 Blaine, 'Encyclop. of Rural Sports,' p. 213. 



Chap. XXI. SELECTION. 233 

circumstances inconceivably complex and liable to change, 
modifications of tlie 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 species and races. 

Domestic races propagate their kind far more truly, 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 how 
and when the several domestic races were formed, who cannot 
have seen the intermediate gradations, for 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. XXL 

descended from a common progenitor, and lie 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 by Man. — There can he 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 
which, 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 Lave 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 follow from long-continued close inter- 
breeding. That methodical selection may be successful, the 
closest attention and discernment, combined with unwearied 
patience, are absolutely 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 effects 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. 
Finally, 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, differ in 
general aspect from closely allied natural species. 



236 SELECTION. Chap. XXL 

Throughout this chapter and elsewhere I have spoken of 
selection as the paramount power, jet 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; yet 
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 dejoend 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 
his 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 
OP EVERY ETND DUE TO CHANGED CONDITIONS OP LIFE — ON THE NATURE 

OF SUCH CHANGES CLIMATE, FOOD, EXCESS OP NUTRIMENT SLIGHT 

CHANGES SUFFICIENT — EFFECTS OF GRAFTING ON THE VARIABILITY OF 

SEEDLING - TREES DOMESTIC PRODUCTIONS BECOME HABITUATED TO 

CHANGED CONDITIONS — ON THE ACCUMULATIVE ACTION OP CHANGED 
CONDITIONS — CLOSE INTERBREEDING AND THE IMAGINATION OP THE 
MOTHER SUPPOSED TO CAUSE VARIABILITY — CROSSING AS A CAUSE OP 
THE APPEARANCE OP 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 probable. 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 the 
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 Linnaeus 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. Yerlot 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 Toorhelm, who kept above 1200 
varieties of the hyacinth, 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, yet really differ. 1 

As Linnaeus has compared the reindeer in number to ants. 
I may add that each ant knows its fellow of the same com- 
munity. Several times I carried ants of the same species 
(Formica rufd) 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. 

1 ' Des Jacinthes,' &c, Amsterdam, lated bv Sir J. E. Smith, vol. i. p. 

1768, p. 43; Yerlot, 'Des Varietes,' 314. The statement in regard to 

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

Linnaeus, '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 2 that an innate tendency to vary 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 

2 Miiller's ' Physiology.' Eng. trans- ce frere alors a, Yienne, et qui lui epi- 
lation, vol. ii. p. 1662. With respect vait en eff'et — ' J'ai mon ophthalmie, 
to the similarity of twins in eonsti- tu dois avoir la tienne.' Quelque sin- 
tution, Dr. William Ogle has given me gulier que ceci puisse paraitre, le fait 
the following extract from Professor n'en est pas moins exact : onnemel'a 
Trousseau's Lectures (' Clinique Medi- pas raconte, je l'ai vu, et j'en ai vu 
cale,' torn. i. p. 523), in which a d'autres analogues dans ma pratique, 
curious case is recorded : — "J'aidonne Ces deux jumeaux etaient aussi tous 
mes soins a deux freres jumeaux, tous deux asthmatiques, et asthmatiques 
deux si extraordinairement ressem- a un effroyable degre. Originaires de 
blants qu'il m'etait impossible de les Marseille, ils n'ont jamais pu de- 
recunnaitre, a moins de les voir l'un meurer dans cette ville, ou leurs 
a cote de l'autre. Cette ressemblance interets los appelaient soiavent, sans 
physique s'etendait plus loin: ils etre pris de leurs acces ; jamais ils n'en 
waient, permettez-moi l'expression, eprouvaient a Paris. Bien mieux, il 
une similitude pathologique plus re- leur suffisait de gagner Toulon pour 
marquable encore. Aiosi l'un d'eux etre gueris de leurs attaques de Mar- 
que je voyais aux neothermes a. Paris seille. Voyageant sans cesse et dans 
malade d'une ophthalmie rhumatis- tous pays pour leurs affaires, ils 
male me disait, ' En ce moment mon avaient remarque que certaines 
frere doit avoir une ophthalmie comme localites leur etaient funestes, que 
la mienne;' etcomme jem'etais recrie, dans d'autres ils etaient exempts de 
.T me montrait quelques jours apres tout phenomene d'oppression." 
une lettre qu'il venait de recevoir de 



240 CAUSES OF YAKIABILITY. Chap. XXII 

reflect on the individual differences between organic beings in 
a state of natnre, 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 
Variability must be looked at as an ultimate fact, necessarily 
contingent on reproduction. 

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 by 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. Now, 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 
mat ernal grandmother. 

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



Chap. XXII. CAUSES OF VARIABILITY. 241 

by thj 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 ; 3 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 
(Secale cereale) has afforded fewer and less marked varieties 
than almost any other cultivated plant ; 4 but it may be 

3 Isid. Geoffroy St.-Hilaiie, 'Hist. 1841, p. 115. 
des Anomalies,' tom. iii. p. 352; Mo- 4 Metzger, 'Die Getrei learten. 

tjum-Tandon, 'Teratologic VYgetale,' 1841, s. 39. 



242 CAUSES OF VARIABILITY. Chap. XXII. 

doubted whether 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 leafing 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 cherry-tree yielded a branch 
bearing fruit of a different shape and colour from the ordinary 
fruit. The prodigy would be enhanced if these varying 
branches were found capable of propagation, not only by 
grafts, but sometimes by 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 Variability. 

From a remote period to the present day, Tinder 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 sixty-three varieties of the 
bamboo are used for various domestic purposes. 5 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 6 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. 7 Nor can we overlook the 

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

4 Annals and Mag. of Nat. 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. o07. 
ties cultivated in Tahiti, see Dr. 6 'Treatise on the Culture of the 

Bennett, in Loudon's ' Mag. of N. Apple,' &c, p. 3. 
Hist.,' vol. v., 1832, p. 484. Also 7 Gallesio, 'Teoria della Ripro 

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



24.4 CAUSES OF VARIABILITY. Chap. XXII. 

fact, though, not immediately connected with our present 
subject, that the plants and shells of the Arctic regions are 
eminently variable. 8 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 ' Geographie Botaniqne,' 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. 9 

Of all the causes which induce variability, excess of food, 
whether or not changed in nature, is probably the most 
powerful. This view was held with regard to plants by 
Andrew Knight, and is now held by Schleiden, more especially 
in reference to the inorganic elements of the food. 10 In 
order to give a plant more food it suffices in most cases to 
grow it separately, and thus prevent other plants robbing its 
It is surprising, as I have often seen, how vigorously 
our common wild species flourish when planted by them- 
selves, though not in highly 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: 11 

8 See Dr. Hooker's Memoir on subject. He states that his canary- 
arctic Plants in * Linn. Transact.,' birds varied in colour, though kept on 

vol. xxiii. part ii. Mr. Woodward, uniform food. 

and a higher authority cannot be 10 'The Plant,' by Schleiden, trans- 
quoted, speaks of the Arctic mollusca lated by Heni'rey, 1848, p. 169. See 
(in his ' Rudimentary Treatise,' 1856, also Alex. Braun, in 'Bet. Memoirs,' 

i as remarkably subject to Ray Soc, 1853, p. 313. 
variation. u Messrs. Hardy and Son, of Mai- 

9 Bechstein, in his ' Naturge- don, in 'Gard. Chronicle,' 1856, p 
schichte der Stubenviigel,' 1840, s. 453. Carriere, 'Production et Fiza 
238, has some good remarks on this \ion des Varietes,' 1865, p. 31. 



Chat. XXII. CAUSES OF VARIABILITY. 245 

" It is a rule invariably with us, when we desire fco 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 nioyenne sont celles qui conservent le mieux leuis 
" 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 affect 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 different 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 suffice to induce varia- 



246 CAUSES OF VARIABILITY. Chap. XXIL 

"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 every extensive 
seed-bed. I have shown in a former chapter what a number 
of well-marked and singular varieties the thorn (Cratcegus 
oxycaniha) 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, 12 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. 13 

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 when grafted on the wild pear. 14 But as the 
pear and quince are distinct species, though so closely related 

» 'Quadruples da Paraguay,' 1839, pp. 266, 268, 313. 
1801, torn. ii. p. 319. u Quoted by Sageret, ' Pom. Phys., 

13 McClelland on Indian Cyprinidae, 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 "be 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, 15 
"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. 16 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 wheat 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. 17 In England, on the other hand, no instance of 
a good pear having been found wild has been recorded ; and Mr. 
Rivers 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 difference between the two countries may be in part 
accounted for by the more favourable climate of France, but chiefly 



15 'The Fruits of America,' 1845, Poiteau's remark is qixoted in ' Gar- 
p. 5. dener's Mag.,' vol. iv.. 1828, p. 385. 

16 M. Cardan, in 'Comptes Ren- See ' Gard. Chronicle,' 1862, p. 335, 
dus,' Dec. 1848, quoted in ' Gard. for another case of a new variety oi 
Chronicle,' 1849, p. 101. the pear found in a hedge in France.- 

17 M. Alexis Jordan mentions four Also for another case, see Loudon's 
excellent pears found in woods in ' Encyclop. of Gardening,' p. 901. 
France, and alludes to others (' Mem. Mr. Rivers has given rne similai 
Acad, de Lyon,' torn. ii. 1852, p. 159). information. 



24:8 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, 18 who regards it as a national calamity that such 
a number of pear-trees are periodically cnt 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 19 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- 
auce of a valuable kind. In North America, where fruit-trees 
frequently spring up in waste places, the Washington pear was 
found in a hedge, and the Emperor peach in a wood. 2 " 

With respect to wheat, some writers have spoken- 1 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 by the roadside in Scotland, but it is not said 
that this latter variety grew where it was found.' 22 

Whether our domestic productions would ever become so 
completely habituated to the conditions under which they 
now 1 vi'. 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.- 3 states that some kinds were at first extremely vari- 
able, but gradually, in one instance after an interval of 

18 Duval, 'Hist, du Poirier,' 1849, aboriginal species. 

j.. j. 20 Downing. -Fruit-trees of North 

19 I infer that this is the fact from America,' p. 422 ; Foley, in ' Transact. 
lions' statement (' Arbres Frui- Hort. Soc.,' vol. vi. p. 412. 

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

:n the woods seedlings resembling 22 'Gardener's Chronicle,' 1841, p. 

all the chief cultivated races of both 38 j 18' , p. 700 ; 1854. p. 650. 

the pear and apple. Van Mons, how- " ' Die Getreidearten,' 1843, s. fry 

ivei 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. — 
We 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. 24 
After several years' culture the Zinnia has only lately (1860) 
begun to vary in any great degree. " In the first seven or 
" eight years of high cultivation, the Swan Eiver daisy 
" {Br achy come iberidifolia) kept to its original colour ; it then 
"varied into lilac and purple and other minor shades." 25 
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 26 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, 27 
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 

24 Sabine, in 'Hort. Transact.,' vol. 26 'The Chrysanthemum, its Bis- 
iii. p. 225 ; Bronn, ' Geschichte der tory, &c.,' 1865, p. 3. 

Natur,' b. ii. s. 119. 2 " 7 < Gardener's Chron.,' 1855, p, 

25 ' Journal of Horticulture,' 1861, 54; 'Journal of Horticulture,' May 
p. 112; on Zinnia, 'Gardener's 9, 1865, p. 363. 

Chronicle,' 1860, p. 852. 



250 CAUSES OF VAKI ABILITY. 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, 28 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 
quickly or slowly when first subjected to new conditions. 
But Dr. Bachman 29 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. Mr. 
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, 30 
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 
k ' 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, 

2S Quoted bv Verlot, • Des Yarietes,' ton, 1855, p. 14. 
& ,18 . 30 Mr. Hewitt, 'Journal of Hort , 

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



Chap. XXII. CAUSES OF VARIABILITY. 251 

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 iheni 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 31 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 I have 
not sufficient 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. 32 This view is evidently not applicable to the lower 
animals, which lay unimpregnated eggs, or to plants. Dr. 
William 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 any 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 

31 Devay, ' 'Manages Consanguins,' 32 Mliller has conclusively argued 

pp. 97, 125. In conversation I h;ive against this belief, ' Elements o/ 

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

s;»iDt- opinion. p. 1405. 



252 CAUSES OF YAE I ABILITY. Chap. XXII 

abnormal structure ; but when she 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 Variability. — In an early part of this 
chapter it was stated that Pallas 33 and a few other naturalists 
maintain that variability 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 widely 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 nut 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 
an I the first appearance of absolutely new characters. Practi- 
cally, whether new or old, they would be new to the breed iD 
which the}' reappeared. 

33 • Act Acad. St. Petersburg,' 1760. part ii. p. 84, &c 



Chap. XXII. CAUSES OF VAEIABILITY. 253 

Gartner declares, 34 and his experience is of the highest value on 
such a point, that, when he crossed native plants which 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. 
AY ben, 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 way to the cross. An opposite conclusion, however, appears 
to me the more probable. According to Kolreuter, 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. 35 

Prof. Lecoq 36 speaks strongly to the same effect in regard to this 
same genus, and asserts that many of the hybrids from Mirabilis 
jaJapa 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 described 37 
certain hybrid Rhododendrons 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 38 
has lately discussed this subject : he states that Eryilirina cristugalli 
had been multiplied by seed for many years, but had not yielded 
any varieties : it was then crossed with the allied E. herbacea, and 
" the resistance was now overcome, and varieties were produced 
" with flowers of extremely different size, form, and colour." 

Prom the general and apparently well-founded belief that the 
crossing of distinct species, besides commingling their characters, 
adds greatly to their variability, it has probably arisen that some 
botanists have gone so far as to maintain 39 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- 



34 ' Bastarderzeugung,' s. 249, 255, 38 Abstracted in ' Gard. Chronicle, 
295. 1860, p. 1081. 

35 'Nora Acta, St. Petersburg,' 39 This was the opinion of the elder 
1794, p. 378; 1795, pp. 307, 313, De Candolle, as quoted in ' Die. Class. 
316; 1787, p. 407. d'Hist. Nat.,' torn. viii. p. 405. Puvis, 

36 'De la Fe'condation,' 1862, p. in his work, ' De la Degeneration,' 
311. 1837, p. 37, has discussed this same 

37 ' Amaryllidacea?,' 1837, p. 362. point. 

33 



254: CAUSES OF VARIABILITY. Chap. XXII 

vated is generally less than 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. 1 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 40 
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 brown steins and bore purple flowers; so that they re- 
sembled the species 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 variability, 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 Koireuter, 41 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 or absorbed by repeated crosses with either pure parent- 



40 ' Compter Rend us,' No vena bre 21, 41 'Nova Acta, St. Tetersbui 

186+, p. bJ8. 179-I-, p. 391. 



Chap. XXII. CAUSES OF VARIABILITY. 255 

form : and a still higher degree of variability when three distinct 
species, and most of all when four species, are blended together by 
successive crosses. Beyond this point Gartner, 42 on whose authority 
the foregoing statements are made, never succeeded in effecting a 
union; but Max AYichura 43 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 44 repeatedly found that when a hybrid was used as a father 
and cither one of the pure parent-sjDecies, 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 
barbutv.s crossed by the hybrid J), chinensi-barbatus were more 
variable than those raised from this latter hybrid fertilised by the 
pure D. barbatits. Max Wichura 45 insists strongly on an analogous 
result with his hybrid willows. Again Gartner 46 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 Variability. — 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. We sh^ll 
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, &c, prolonged during several 
generations, certainly modify either the whole organisation or 
certain organs; and it is clear at least in the case of bud- 
variation that the action cannot have been through the repro- 
ductive system. 

42 ' Bastarderzeugung,' s. 507, 516, 4i ' Bastarderzeugung,' s. 452, 507 
572. 45 < Die Bastardbefruchtung,' s. 56 

43 ' Die Bastardbefmchtung,' &c, 46 ' B.tstarderzeugung,' s. 423. 
1S65, s. 24. 



256 CAUSES OF VARIABILITY. Chap. XXIL 

With respect to the part which, the reproductive system takes in 
causing variability, we have seen in the eighteenth chapter that 
even slight changes in the conditions of life 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. 
We 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 47 was struck with the parallelism between the excessive 
variability of hybrids when crossed and recrossed in various ways, — 
these hybrids having their reproductive powers more or less affected, 
■ — and the variability of anciently cultivated plants. Max AYichura 4 * 
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 B. ccesius and 
idceus. 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 



47 ' Dritte Fortsetzucg,* &c, 1766, Berkeley on the same subjeH, in 
s 35. 'Journal oi Royal Hurt. Sue./ IK'ib, 

48 'Die Bastardbefruchtnng.' &c, p. 80. 
186"., s. 92: see also the Rev. M. J. 



Chap. XXII. CAUSES OF VARIABILITY. 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. 49 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 being injured whilst in the mother's 
womb or in the egg. Thus I. Geoffroy Saint-Hilaire 50 asserts that 
poor women who work hard during their pregnancy, and the mothers 
of illegitimate children troubled 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. 51 
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 larvae of which do not possess either antennae or legs ; 
and in these cases, as Quatrefages 52 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. 



49 Di. P Lucas 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. 

30 ' Hist, des Anomalies,' torn. iii. 5a See his interesting work, ' Meta- 

p. 499. morphoses de 1'Homme,' &c, 18G2, p. 

« Ibid., torn. iii. pp. 392, 50£ The 129. 



258 CAUSES OF VARIABILITY. Chap. XXil. 

In accordance with the facts • above given, which prove that in 
many cases a close relation exists between variability and the sterility 
following from changed conditions, we may conclude that the ex- 
citing canse 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 G-artner's and YTichura'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 53 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 exposed. Changes of any kind in tlje 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 have already become variable, increases 
in the offspring the tendency to further variability, by the 
unequal commingling of the characters of the two parents, by 
the reappearance 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 on 

53 ' Diitte Fortsetzung,' &c, s. 123; ' Bastarderzeugung,' s. 249. 



Chap. XXII. CAUSES OF VABIABILITY. 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. XXI1JL. 



CHAPTER XXIII. 

DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS OF 

LIFE. 

SLIGHT MODIFICATIONS IX PLANTS FROM THE DEFINITE ACTION' OF CHANGED 
CONDITION'S, 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 OF ORGAN'IC BEINGS IN A STATE OF NATURE 
THROUGH THE DEFINITE ACTION OF EXTERNAL CONDITIONS — COMPARISON 
OF AMERICAN AXD EUROPEAN TREES — GALLS — EFFECTS OF PARASITIC 
FUNGI — COXSIDE RATION'S OPPOSED TO THE BELIEF IX THE POTENT 
INFLUENCE OF CHAXGED EXTERXAL COXD1TIOXS — PARALLEL SERIES OF 
VARIETIES — AMOUNT OF VARIATION DOES XOT CORRESPOND WITH THE 
DEGREE OF CHANGE IX THE CONDITIONS— RCD-VARIATION — MONSTROSI- 
TIES PRODUCED BY UNNATURAL TREATMENT — SUMMARY. 

If we ask ourselves why this or that character has been modi- 
fied under domestication, we arc. in most cases, lost in utter 
darkness. Many naturalists, especially of the French school, 
attribute every modification to the " monde 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 many 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. By the 
term indefinite action I mean an action which causes one in- 
dividual to vary in one way and another individual in another 
way, as we often see with plants and animals after they have 
s i ejected for some generations to changed conditions of 
life. But we know far too little of the causes and laws of 



Chap XXlIL 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 effects of 
selection ; for selection depends on the preservation by man 
uf 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 unconscious 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. XXIII. 

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 1 that when a variable 
species enters a new and isolated country, although the varia- 
tions may be of the same general 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 feet 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 within 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, 2 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 JSloimh ? Where do high-coloured flowers revel better than at 



1 ' Ueber den Einflu?s der Isolirun,' - 'Gardener's Chronicle,' 1853, p 

»uf die Artbildung.' 1872. 183. 



Chap. XXIH. CONDITIONS OF LIFE. 263 

" "Woolwich and Birmingham ? Yet in no two of these districts do 
" the same varieties attain an equal degree of excellence, although 
" each may he 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 3 : the Lady Cooper 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 4 states that he procured 
cuttings of an old and w T ell-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 5 asserts that in 1S61 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 6 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 ' 7 remarked 
how singular it was that this year many Calceolarias tended to 
assume a tubular form. With Heartsease 8 the blotched sorts 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 9 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. Yerlot 10 states that the variegated strawberry 



* Mr. Wildman, < Floricultural 6 Ibid., 1862, p. 83. 

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

Chron.,' 1843, p. 86. 8 Ibid., 1863, p. 628. 

4 Mr. Kobson, in ' Journal of Horti- 9 ' Journal of Hort./ 1861, pp. 6\ 
culture/ Feb. 13th, 1866, p. 122. 309. 

5 'Journal of Horticulture,' 1861, 10 ' Des Varietes,' &c, p. 78. 
p. 24. 



261 DEFINITE ACTION OF THE Chap. XXIII 

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 casw 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 often 
modified by a change which seems to us slight. The Hemlock is 
said not to yield conicine in Scotland. The root of the Aeon Hunt 
h'ij edus becomes innocuous in frigid climates. The medicinal pro- 
perties of the Digitalis are easily affected by culture. As the Pistacia 
fcntiscus 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 Xorth America. 11 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 {RobinicC) when grown in 
England is nearly worthless, as is that of the Oak-tree when grown 
at the Cape of Good Hope. 1 - Hemp and flax, as I hear from Dr. 
ier, flourish and yield plenty of seed on the plains of India, 
bnt their fibres are brittle and useless. Hemp, on the other ham], 
fails to produce in England that resinous matter which is so largely 
use-l 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, 
Qg to Naudin, to improve an old kind than to introduce a 
new one into any locality. The seed of the Persian Melon pro- 
hear Paris fruit inferior to the poorest market kinds, but at 
Bordeaux yields delicious fruit. 1J Seed is annually brought from 
Thibet to Kashmir, 14 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 



11 Engcl, ' Sur les Prop. Medi les Chronicle/ 1849, p. 355; 

antes,' 1860, pp. 10, -o. On 1862, p. 112 . 
changes in the odours or' plants. l2 Hooker, c Flora Indica,' p. 32. 

Dtlibert's Experiments, quoted by l3 Naudin, ' Annales des Sc. Nat.,' 

LieAman, ' Inventions,' vol. ii. p. 3+4; 4th series, Bot., torn, xi., 1859. p. 81. 

and Nets, in Ferus>ae, 'Bull, des Sc -Gardener's Chronicle,' ' - 

. With u :•■: bi ., vol 

the rhnbarl , &c lso ii p. 143. 



Chap. XXIII. CONDITIONS OF LIFE. 265 

varieties of the kidney-bean, remarkable for the beauty of their 
seeds, but the Eev. M. J. Berkeley 15 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 
wuse a so-called native kind which was formerly introduced 
from South America ; all these plants belong to the same 
species and aro alike in appearance, but the cochineal insect 
flourishes only on the native kind, on which it thrives 
prodigiously. 16 Humboldt remarks 17 that w^hite men " born 
in the torrid zone walk barefoot with impunity in the same 
apartment wdiere 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 18 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 



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

1113. (' Beitrag zur Kenntniss der Ehyn- 

18 Eoyle, ' Productive Resources of choprion :' Moscow, 1864, s. 39), and 

India,' p. 59. by others. 

17 'Personal Narrative,' Eng. trans- 18 ' Organic Chemistry/ Eng. trans« 

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



266 DEFINITE ACTION OF THE Chap. XXIII 

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, 19 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. 20 Even in the different departments of Prance it is found 
that the various infirmities which render the conscript unfit for 
serving in the army, prevail with remarkable inequality, revealing, 
as Boudin observes, that many of them are endemic, which other- 
wise would never have been suspected. 21 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 
>rarily 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 
. Dr. Falconer informs me that he has seen the English 
Ril »ston-] tippin apple, a Himalayan oak, Prunus and Pyrus, 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 22 " 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 



9 Pilchard, ; Phys. Hist, of Man- tuknn from Dr. Boudin's ' Geographic 

551, vr.l. i. j.. K'"'. et Statistique Medicale,' 1857, torn. 

*• Darwin, 'Journal of Researches,' i. pp. xliv. and Hi.; torn. ii. p. 315. 
184-5, p. 4 -4-. " 'Ceyion,' by Sir J. E. Tciinent, 

21 Tnese statements on disease are voL i., 1859, p. 89. 



Chap. XXIIL CONDITIONS OF LIFE. 267 

in certain tropical countries. 23 The Rhododendron cih'atum produced 
at Kew flowers so much larger and paler-coloured than those which 
it bears on its native Himalayan mountain, that Dr. Hooker 2i 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 oi 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. 25 Dryness seems generally to favour the 
hairiness or villosity of plants. Gartner found that hybrid 
Yerbascums became extremely woolly when grown in pots. Mr. 
Masters, on the other hand, states that the Opwntia leucotricha " is 
" well clothed with beautiful white hairs when grown in a damp 
" heat, but in a dry heat exhibits none of this peculiarity." 26 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 27 
gives some instances from his own experience. Odart, who insists 
strongly on the permanence of the varieties of the grape, admits- 8 
that some varieties, when grown under a different climate or treated 
differently, 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. 29 

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." 30 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 



23 Godron, 'De l'Espece,' torn. ii. 27 ' Pom. Phys.,' p. 136. 

p. 52. 28 'Ampelographie,' 1849, p. 19. 

24 ' Journal of Horticultural Soc.,' 29 Gartner, ' Bastarderz.,' s. 606, 
rol. vii., 1852, p. 117. has collected nearly all recorded facts. 

25 'Journal of Hort. Soc.,' vol. i. p. Andrew Knight (in 'Transact. Hort. 
160, Soc.,' vol. ii. p. 160) goes so far as to 

26 See Lecoq, on the Villosity of maintain that few varieties are abso- 
Plants, ' Geograph. Bot.,' torn. iii. pp. lutely permanent in character when 
287, 291 ; Gartner, 'Bastarderz.,' s. propagated by buds or grafts. 

261 ; Mr. Masters, on the Opuntia, 30 Mr. Blyth, in 'Annals and Mag 

in ' Gard. Chronicle,' 1846, p. 444. of Nat. Hist.,' vol. xx., 1847, p. 391. 



268 DEFINITE ACTION OF THE Chap. XX1I1 

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 produced in the fleece of sheep, 
in about three generations. Dr. Falconer states 31 that the Thibet 
mastiff and goat, when brought clown 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 32 
attributes the thickness of the fleece to the severe winters, and its 
silky lustre to the hot summers. Burnes states positively 33 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. 34 It 
has been asserted on good authority 35 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. 36 

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 
. and probably is to a great extent true. But as far as form is 
concerned, we must not overlook the more potent influence of 
I 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 Emit pigeons, all kept 
together and supplied with abundant nourishment. Nevertheless 
there can be little doul it 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 
oi' selection. For instance, Prof. Biitimeyer 3/ " shows that the bones of 



11 ' Natural History Review,' 1802, 'Hist. Nat. Gen.,' torn. iii. ]>. 438. 
p. 113. 3ri Azara ha- made -'.in'' good re- 

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

i '. J-. 275. du Paraguay,' torn. ii. p. 337. 

33 'Travels in Bokhara,' vol. iii. p. an account of a family of naked mice 
151. produced in England, ' Proc. Zoolog. 

• also, on the influence of Soc,' 1856, p. 38. 
marshy pastures on the wool, Godron, 3: 'Die Fauna der Pfahlbauten, 

n. ii. p. 22. 1861, s. 15. 
35 Isidore Geoffroy ^aint-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 ' Vorstudien/ 38 and 
doubt that, with the highly improved races of the pig, abundant 
food has produced a conspicuous effect on the general form of the 
body, on the breadth of the head and face, and even on the teeth. 
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 lost, 
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 39 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 tome 
some much more remarkable facts of the same nature. The natives 
of the Amazonian region feed the common green parrot (Chrysotis 
/estiva, Lima.) 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 garrulus, 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 40 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 
fi paint, and inoculate the fresh wound with 'the milky secretion 
" from the skin of a small toad. The feathers grow of a brilliant 



38 'Schwemesehadel/ 1864-,s. 99. 40 A. R. Wallace, 'Travels on th« 

39 ' Travels in Siberia/ Eng. trans- Amazon and Eio Negro/ p. 294. 
lat., vol. i. p. 228. 



270 DEFINITE ACTION OF THE Chap. XXIII. 

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

Bechstein 41 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 i2 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. TVith 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 43 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 of growth 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 different 
colour or produce moths differiug in colour. 44 

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 tlie lurid tints of insects, and on the succulency of plants. 
Mr. Herbert Spencer 46 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 
acta d on by the surrounding conditions, and they invariably differ 
in intimate structure. - gain the upper and lower surfaces of 
true leaves, as well as of steins and petioles, when these assume 



41 ' Naturgeschichtc dei Stuben- la Soc. Imp. d'Acclimat./ torn. viii. p. 

vogel,' 1840, s. 262 - 563. Fur analogous facts from 

4 - • HDt. Nat Gen.,' torn. iii. p. Dahlbom on Hymenoptera, see Wesfc- 

402. wood's • Modern Class, of Insects.' vol. 

4J ' Dull, de la Soc. Imp. d'Accli- ii. p. 98. See also Dr. L. Moller, 

mat.,' torn. ▼iii. p. 351. 'Die Abhiingigkeit der Insecteii.' 

S an account of Mr. Gregson's l*'i7. s. 70. 

iments on the Abcaxus <jru±?u- 4i "The Principles of Biology,' vol. 

. • Proa Entomolog. Soc.,' Jan. ii., 1866. The present chapters were 

• :e>e experiments have written before I had read Mr. Her- 

ofirmed by Mr. Greening, in bert Spencer's work, so that I have 

• Proa of the Northern Entomolog. not been able to make so much u<e of 

Soc.,* July 28th, 1862. Forthe effects it as I should otherwise probably 

iterpillars. se t a curious have done, 
account by M. Michely, in ' Dull, de 



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 variations which are 
serviceable to the organism, and which have arisen independently 
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 
especially by Mr. J. A. Allen, that, with birds, many species 
differ in tint, size of body and of beak, and in length of tail, 
in proceeding from the North to the South ; and it appears 
that these differences must be attributed to the direct action 
of temperature. 46 With respect to plants I will give a some- 
what analogous case: Mr. Meehan, 47 has compared twenty- 
nine kinds of American trees with their nearest European 
allies, all grown in close proximity and under as nearly as 
possible the same conditions. In the American species he 
finds, w r ith 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 are 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- 
firmed action of a different climate. 

46 Professor Weismann comes to other authors on the present subject ; 

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

certain European butterflies .in his schlechte Arten,' 1866. 
valuable essay, 'Ueber den Saison- 47 ' Proc. Acad. Nat. Soc. of Phila* 

Dimorphismus,' 1875. I might also delphia," Jan. 28th, 1862. 
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 Xova 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 Cynips with its 
sub-genera ; and Air. B. D. Walsh 48 states that he can add 
many others to the list. One American species of willow, 
the Salic lurnulis, 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 whollv 
changed in appearance. Galls are produced in every quarter 
of the world; of several sent to me by Mr. Thwaites from 
Ceylon, some were as symmetrical 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 ; tlms M. Lacaze-Duthiers 49 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 produced by insects of various orders, but the 

< s 5 t Mr. B. D. Walsh's excellent I • 
papers in 'Prue. Entomolog. 8 49 See his admirable 'Histoire ilea 

Philadelphia, 5 Dec. 18-56, p. 284-. Galles,' in 'Annal. des Sc. Nat. Bo*.,' 

With respect to (he willow, see ibid., 3rd series, torn. xi.\., 1853, 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 ; 50 it is certain that they 
are almost completely developed before the larvee are hatched. 
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 51 remarks, afford good, constant, and 
definite characters, each kind keeping as true to form 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." 52 
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 induce widely different results. In some few 
cases the same species of gall-gnat produces on distinct species 
of willows galls which cannot be distinguished ; the Cynips 
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. 53 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 variuiis 

50 Kirby and Spence's 'Entomology,' 52 Mr. B. D.Walsh, ibid., p. G3J, 
1818, vol. i. p. 450 ; Lacaze-Duthiers, and Dec. 1866, p. 275. 

ibid., p. 284. 53 Mr. B. D. Walsh, ibid., 1864, pp 

51 '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 Ave 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. 54 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 parruts are excellently adapted to show us how 
powerfully and singularly 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 remarkable effects which parasitic 
fungi sometimes produce on plants. Reissek 56 has docribed a 
Thesium, affected by an (Ecidium, which was greatly modified, and 
assumed some of the characteristic features of certain allied species, 
or even genera. Suppose, says Reissek, "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 



54 Laeaze-Duthier*, ibid., pp. 325, by Dr. M. T. Masters, Royal Institu- 
328. ... March 10th, 1800. 

" 'Linna/a.' vol. xvii.. 1843 ; quoted 



Chap. XXTTL CONDITIONS OF LIFE. 275 

remark to show how profoundly, yet in how natural a manner, this 
plant must have been modified by the parasitic fungus. Mr. 
Meehan 56 also states that three species of Euphorbia and Portulaca 
olereacea, which naturally grow prostrate, become erect when they 
are attacked by the CEcidium. Euphorbia metadata 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 hypericifolia. 

Facts and Considerations opposed to the belief that the Conditions 
of Life act in a potent manner in causing definite Modifications 
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 5 " 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 
portion 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 • Prec. Acad. Nat. Sc, Philadcl- 57 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. 

TVe 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 varying 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 kept 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 uniformly as 
is p tssible. 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 
obs( rv. ,1 amongst the Canres 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. Afeehan 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 
—nine a distinctive character. Dr. M. Masters has recorded a 
striking fact 5 " bearing on this subject: he raised numerous plants 



58 ' Garden l-i's Chronicle,' 1857, p. 629. 



Chap. XXIII. CONDITIONS OF LIFE. 277 

of Fyhiscus syriacus from seed collected in South Carolina 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 species 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. 
Max .veil Masters has remarked to me, in the same species of plant. 

We niay at least conclude, th-it the amount of modification 
wdiich 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 in 
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 yielded 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 



2 i 5 DEFINITE ACTION' OF THE Chaf. XXHI 

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

Bud-Tariation is, also, important under our present point of 
view. In some few cases, as when 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 appear by bud-variation, which do not occur in the 
parent-species or in any allied species. Ave 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, fur 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 t" 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. 
N rines dilV ry one knows, from peaches in their 

thness, 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 acquire 1. th .t a nectarine produced by bud-vari;tti"ii 
has propagated itself by seed. To guard against the supposi- 
tion that there is some fundamental distinction 1 elween 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. 
Now is it possible to conceive external conditions more 
closely alike than those to which the buds on the same tree 
are exposed r Yet one bud alone, out of the many thousands 
borne ly the same tree, lias suddenly, without any apparent 

produced a nectarine But the case is even sti 
than this, for the same flower-bud has vielded 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, differ 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 Geoffroy 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, 59 remarks " that the various species of monstrosities 
" are not determined by specific causes ; the external agencies 
" which modify the development of the embryo 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. 60 We may take a still 
more specific instance : seven pigeons were struck by rattle- 
snakes : 61 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, 
&g ; others again showed no visible lesion in any organ. It 
is well known that excess in drinking causes different diseases 

59 'Memoire sur la Production his ' Vie, Travaux,' &c, 1847, p. 290. 

Artificielle des Monstruosites,' 18^2, 60 Paget, ' Lectures on Surgical 

pp. 8-12 ; ' Recherches sur les Conai- Pathology,' 1853, vol. i. p. 483. 

t : ons, &c, chez les Monstres,' 1863, 61 ' Researches upon the Venom of 

p. 6. An abstract is given of the Rattle-snake,' JaD. 1861, by Dr. 

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



280 DEFINITE ACTION OF TliE Chap. XXIII 

in different men ; "but in the tropics the effects of intemper- 
ance differ from those cansed in a cold climate ; 62 and in this 
case we see the definite influence of opposite 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 directly, though not definitely, in 
causing modifications of structure. 

Summary. — There can he 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 European 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 

n Mr. Sedgwick, in ! British an;l Foreign Medico-Chirurg. Review,' Julj 
1863, p. 175. 



Chap. XXIII. CONDITIONS OF LIFE. 281 

state of nature may be modified in various definite ways 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 different 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. 

throughout Europe and North America, and on which a 
single bud suddenly produced the red magnum bonum. We 
should also bear in mind that distinct varieties, and even 
distinct species, — as in the case of peaches, 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-variation 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 
plant 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. We 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. 63 

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 effect. In the next chapter it will be shown that 
the increased use or disuse of various organs produces 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. 

63 Professor Weismann argues 'Saison-Dimorphismusder Schmetter* 
strongly in favour cf this view in his ling",' 1875, pp. 40-4:3. 



Chap. XXIV. LAWS OF VARIATION : NISUS FORMATIYUS. 283 



CHAPTER XXIV. 

LAWS OF VARIATION — USE AND DISUSE, ETC. 

KI8US FORMATIYUS, OR THE CO-ORDINATrNG POWER OF THE ORGANISATION — 
ON THE EFFECTS OF THE INCREASED USE AND DISUSE OF OliGANS— 
CHANGED HABITS OF LIFE — ACCLIMATISATION WITH ANIBIALS AND PLANTS 
— VARIOUS METHODS BY WHICH THIS CAN BE EFFECTED — ARRESTS OF 
DEVELOPMENT — 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 arbitrary. 

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 physiologists as nisus formativus. 

Blumenbach and others l 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 plants. 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 



1 ' An Essay on Generation,' Eng. 209. 
translat., p. 18; Paget, 'Lectures on 2 'An Essay on Animal ReproJnc* 

Surgical Pathology,' 1853, vol. i. p. tion,' Eng. translat., 1769, p. 79. 



284 LAWS OF VARIATION. Chap. XXJV. 

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- 
"rnents of muscles, ligaments, &c, become as complete as before." 3 

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 : with certain Orthopterous insects the large hind 
legs are reproduced of smaller size : 4 the white cicatrice which in 
the higher animals unites the edges of a deep wound is not formed 
of perfect skin, for elastic tissue is not produced till loug afterwards. 5 
" The activity of the nisus formativus," says Blumenbach, " 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 6 
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 antennas up 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 part in the repair of injuries. 
AVhen 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. 7 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 apart 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 
structures reproduced, but new structures are formed. Thus, after 
inflammation :i fo)se membranes," furnished with blood-vessels, 
lymphatics, and nerves, are developed ; or a foetus escapes from the 

3 Carpenter's - Principles of Comp. Phys.,' p. 479. 

Physiology,' 1854, p. 4' 9. 7 Prof. Marey's discussion on the 

4 Charlesworth's 'Mag. of Nat. power of co-adaptation in all parts of 
Hist ,' vol. i.. 1S'>7, p. 145. the organisation is excellent. 'La 

5 Paget, 'Lectures on Surgical Machine Animate,' 1873. chap. ix. Set 
Pathology, 5 vol. i. p. 239. also Paget, 'Lectures,' &c, p. 257. 

• 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 hydrocephalus the open 
and dangerous spaces in the skull are filled up with new bones, 
which interlock by perfect serrated sutures. 8 But most physiolo- 
gists, especially on the Continent, have now given up the belief in 
plastic lymph or blastema, and Virchow 9 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 ; adhesions of the iris may 
" become black apparently from the production of pigment-cells like 
" those of the uvea." i0 

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. 11 Yet this power is not more 
wonderful than the growth and development of every single creature, 
more especially of those which are propagated by fissiparous 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 Banke 12 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 13 also accounts 
for the long, thick, dark-coloured hairs which occasionally 

8 These cases are given by Blumen- 12 'Die Blutvertheilung, &c. der 
bach in his 'Essay on Generation,' pp. Organe,' 1871, as quoted by Jaeger, 
52, 54. ' In Sachen Darwin's,' 1874, p. 48. 

9 ' Cellular Pathology,' trans, by See also H. Spencer, ' The Principles 
Dr. Chance, 1860, pp. 27, 441. of Biology,' vol. ii. 1866, chap. 3-5. 

10 Paget, 'Lectures on- Pathology,' 13 'Lectures on Pathology,' 1853, 
vol. i., 1553, p. 357. vol. i. p. 71. 

11 Paget, ibid., p. 150. 



286 LAWS OF VARIATION. Ohap. XXIV. 

grow, even in. young children, 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 sis 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, 14 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, 15 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. 16 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 17 acknowledges 
this difficulty, and gives as an instance the thorns on trees 

14 'Comptes Rendus,' Sept. 26th, 16 Ibid., vol. ii. p. 269. Sachs, 
1864. p. 539. 'Text-book of* Botany,' 1875, p. 734. 

15 H. Spencer, 'The Principles of 1; 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 directty exciting cause ; and as 
the hardness of these parts is of manifest service to the plant, 
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, 18 
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 months. 19 The 
Proteus is furnished with branchiae as well as with lungs : and 
Schreibers 20 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 in- 



18 Paget, ' Lectures on Pathology,' p. 10) a curious account of the atrophy 
vol. ii. p. 209. of the limbs of rabbits after the de« 

19 Miiller's ' Phys.,' Eng. translat., struction of the nerve. 

pp. 54, 791. Prof. Pieed has given 20 Quoted by Lecoq, in ' Geograjih. 

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



288 LAWS OF VARIATION. Char XXIV 

definite variability, that several generations mnst 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 power 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 prominence of its crest, 
the length of the scapulae 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 hah' on a dog with 
the amount of exercise which 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 G alius banhiva. With ducks, 
the crest of the sternum is affected in the eame manner as in the 
foregoing cases : the furculum, coracoids, and scapulae are all reduced 
in weight relatively to the whole skeleton : the bones of the wings 
are shorter and lighter, and the bones of the legs 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 21 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 proportion ; 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 siik- moths, which have 



Das Abandei;. 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. With animals 
living a free life and occasionally exposed to severe compe- 
tition the reduction would tend to be greater, as it would be 
an advantage to them to have the development of every 
superfluous part saved. With highly-fed domesticated animals, 
on the other hand, there seems 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 pig, the shortened 
legs and snout, the form of the articular condyles of the 
occiput, and the position of the jaws with the 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. 22 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. AVith respect to cattle, Professor Tanner has 
remarked that the lungs and liver in the improved breeds 
" are found to be considerably reduced in size when compared 
" with those possessed by animals having perfect liberty ;" 23 

22 Xathusius, ' Die Racen des Nathusius : ' Der Schadel des Ma&ken« 

Schweines,' 1860, s. 53, 57 ; ' Vor- schweiues,' 1870. 
studien .... Schweineschadel,' 1864, 23 'Journal of Agriculture of High 

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



290 LAWS OF VARIATION. Chap. XXIV. 

and the reduction of these organs affects the general shape 
of the body. The canse of the reduced lungs in highly -bred 
animals which take little exercise is obvious; and perhaps 
the liver may be affected by the nutritious and artificial food 
on which they largely subsist. Again, Dr. "Wilckens asserts 24 
that vaiious parts of the body certainly differ in Alpine aid 
lowland 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."- 5 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,- 6 "rarely gives more than tvro or three pints of milk 
" daily, and, should her calf be taken from her, she absolutely 
" refuses to give any." TVe 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 effects 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. 27 

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. 

-' : Landwirth. Wochenblatt/ No. in South America, see Aug. St. -Hilaire, 
10. ' Voyage dans la Province do Govaz,' 

25 ' Lectures on Surgical Pathologv,' torn. i. p. 71. 

1853, vol. i. p. 27. 2r Brickell's 'Nat. Hist, of North 

26 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 Eussia, 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 every passing sound, and 
especially to ascertain the direction whence it comes, there io 
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 28 
to disuse, for animals protected by man are not compelled 
habitually to use their ears. Col. Hamilton Smith 29 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 with 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 Soman period." Godron also has remarked 
" that the pigs of the ancient Egyptians had not their ears 
" enlarged and pendent." 30 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 
droop, 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 Vithzucht,' 

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

nal of Asiatic Soc. of Bengal,' vol. xvi., 29 ' Naturalist's Library,' Dogs, vol. 

1847, p. 1006, &c. &c. On the other ii., 1840, p. 104. 

hand, Dr. Wilckens argues strongly 30 ' De l'Espece,' torn, i., 1859, p. 

against the belief that the drooping 367. 
of th» ears is the result of disuse : 



292 LAWS OF VARIATION. Chap. XXIV. 

Tlie epidermis on our hands is easily thickened, as every 
one knows, by bard work. In a district of Ceylon tbe sbeep 
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. 31 

The mucous membrane which lines the stomach is con- 
tinuous with the external skin of the body ; 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 (Larus tridactylus) 
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 
Larus argentatus, which in the spring frequents the corn- 
fields and feeds on the seed. The 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. 32 

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 Geoffroy has remarked, 

31 'Ceylon,' by Sir J. E. Tennent, as quoted in Macgillivrav's 'British 
1859. vol. ii. p. 531. Birds,' vol. v. p. 550: Menetries, as 

32 For the foregoing statements, see quoted in Bronn's ' Geschichte der 
Hunter's "Essays and Observations.' Natnr/JJ. ii. s. 110. 

[861, vol. ii. p. 329 ; Dr. Edmondston, 



Cjiap. XXIV. CHANGED HABITS OF LIFE. 293 

the several species of cats are so closely allied that the 
comparison is probably a fair one. The in 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. 33 

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. 34 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. 1 he domestic hog is fond of barley, 
the wild boar is said to disdain it ; and the disdain is partially 
inherited, for some } T oung wild pigs bred in captivity showed 
an aversion for this grain, whilst others of the same brood 
relished it. 35 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 

33 These statements on the intestines borne,' 1825, vol. ii. p. 121. 
are taken from Isidore Geoffroy Saint- 35 Burdach, 'Traite de Phys.,' torn. 

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

427. 441. ' L'Hered. Nat.,' torn. i. p. 388. 

3* Gilbert White ' Nat. Hist. Sel- 



294 LAWS OF VARIATION. Chap. XXIV 

be fed ; but they would not touch swill, which was devoured 
by the other pigs. Au 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. 36 The caterpillars of the 
Bombyx hesperus 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. 37 

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 
Egyptian goose the rate of change with respect to the season 
has been recorded. 33 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 Tallisneria has been largely natural- 
ised. The cows were observed by Prof. Wyman to keep their 
heads immersed for " a period varying from fifteen to thirty- 
five seconds.'" 39 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 

36 This find several other cases are 563. 

given by Colin, ' Physiologie Comp. 38 Quatrefages, ' Unite de l'Espece 

de> Animaux Dom.,' lSo-i, torn. i. p. Humaine,' 1861, p. 79. 

426. 39 'The American Naturalist,' Af, 

37 M. Michely de Cayenne, in ' Bull. 1871, 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 immediately 
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 Eicinus in England, and as, according to Captain 
Mangles, with many varieties of the heartsease. Von Berg 40 
raised from seed of Verbascum phamiceum, which is usually a 
biennial, both annual and perennial varieties. Some de- 
ciduous bushes become evergreen in hot countries. 41 Rice 
requires much water, but there is one variety in India which 
can be grown without irrigation. 42 Certain varieties of the 
oat and of our other cereals are best fitted for certain soils. 43 
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 varieties 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 European dogs do 
not succeed well in India, and it is asserted, 44 that no one has 
there succeeded in keeping the Newfoundland long alive ; but 
then it may be argued, and probably with truth, that these 

40 ' Flora,' 1835, B. ii. p. 504. 43 < Gardener's Chronicle,' 1850, 

41 Al ph. da Candolle, ' Geograph. pp. 204, 219. 

Bot.,' torn. ii. p. 1078. 44 Rev. R. Everest, < Journal Aa 

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



29 G LAWS OF VARIATION. 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 
Youatt, 45 not one brought " 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. 46 It is 
almost 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, 47 though 
so tine and vigorous in England, suffers more from frost than 
any other breed. The Arrindy silk moth introduced from 
Bengal, and the Ailanthus 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 ; 48 yet they differ much in constitution : the 
Indian form " will nourish 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 ciimates ; 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 was known that 
succeeded in England; and with apples, 49 not one succeeds. Though 
the American varieties can withstand a severer winter than ours, the 



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

16 Royle, 'Prod. Resources of India,' quoted in the 'Reader,' 1863, Nov 

p. lo3. 13th. 

47 Tegetmeier, ' Poultry Book,' 4fl See remarks bv Editor in ' (lard 
1866, p. 102. Chronicle,' 1848, p. 5. 

48 Dr. II. Paterson, in a paper com- 



Chap. XXIV. ACCLIMATISATION. 297 

summer here is not hot enough. 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. 50 This power in the flower of 
resisting cold and afterwards producing fruit does not invariably 
depend, as we know on good authority, 51 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. 52 Near 
Moscow, Prince Troubetzkoy planted for experiment in the open 
ground several varieties of the pear, but one alone, the Poire san> 
Pepins, withstood the cold of winter. 53 We thus see that our fruit- 
trees, like distinct species of the same genus, certainly differ from 
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 ; " 5i 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 wheat. 55 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 wholly barren 
" spikes or furnished with only two or three miserable seeds, while 
" West Indian seed by its side yielded an enormous harvest." 5(i 
Here is another case of close adaptation to a slightly cooler climate ; 
a kind of wheat which in England may be used indifferently 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. 57 

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 54 ' Gard. Chronicle,' 1851, p. 39(3. 

from Decaisne. 55 Ibid., 1862, p. 235. 

51 J. de Jonghe, of Brussels, in 56 On the authority of Labat, 
* Gard. Chronicle,' 1857, p. 612. quoted in 'Gard. Chron.,' 1862, p. 

52 Ch. Martius, 'Voyage Bot. Cotes 235. 

Sept. de la Norvege,' p. 26. « MM.Edwards and Colin, < Annal 

53 ' Journal de l'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 with 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 early flowering and early seeding 
varieties deserves to be considered as one form of acclimatisation. 
Hence 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. 58 On the authority of 
Linnaeus, 59 I may quote an analogous case, namely, that in Sweden 
tobacco raised from home-grown seed ripens its seed a month 
sooner and is less liable to miscarry than plants raised from foreign 
seed. 

With the Vine, differently from the maize, the line of practical 
culture has retreated a little southward since the middle ages ; 60 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 difference in the constitution of the 
several varieties, — some being hardy, whilst others, like the muscat 
of Alexandria, require a very high temperature to come to perfection. 
According to Labat, 61 vines taken from France to the West Indies 
succeed with extreme difficulty, 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 
ycars,.than had been effected by grafting old varieties during many 
ages. 62 I may add that Eisso 03 describes some Portuguese varieties 

58 ; Olograph. Bot..' p. 337. p. 339. 

59 'Swedish Acts,' Eng. translat., G1 ' Gard. Chronicle,' 1862, p 235. 
1739— to, vol. i. Kalm, in his 'Travels,' 62 Gallesio, ' Teoria della Ripro- 
vol. ii. p. 166, gives an analogous duzione Veg.,' 1816, p. 125 ; and 
case with cotton-plants raised in Xew ' Traite du Citrus,' 1811, p. 359. 
Jersev from Carolina seed. 63 ' Essai sur l'Hist. des Orangers/ 

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



Chap. XXIV. ACCLIMATISATION. 299 

of the orange as extremely sensitive to cold, and as much tenderei 
than certain other varieties. 

The peach was known to Theophrastus, 322 b.c Gi According to 
the authorities quoted by Dr. F. Eolle, 65 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." m 

I will briefly give a few other cases. A variety of Magnolia 
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 I860 " 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 (Cvnvolvuhis batatas) which are suited for warmer, 
as well as for colder, climates. 87 

The plants as yet mentioned have been found capable of 
resisting an unusual degree of cold or heat, when fully grown. 
The following cases refer to plants whilst young. In a large 
bed of young Araucarias of the same age, growing close to- 
gether and equally exposed, it was observed, 68 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 roses, see 'Gard. 
Bot.,' p. 882. Chron.,' I860, p. 384. For the yew, 

65 'Ch. Darwin's Lehre von der ' Journal of Hort.,' March 3rd, 1863, 
Entstehung,' &c, 1862, s. 87. p 174. For sweet potatoes, see Col. 

66 Decaisne, quoted in ' Gard. Chro- von Siebold, in ' Gard. Chron.,' 1855, 
nicle,' 1865, p. 271. p. 822. 

67 For the magnolia, see Loudon's 68 The Editor, ' Gard. Chron.,' 1861, 
'Gard. Mag.,' vol. xiii., 1837, p. 21. p. 239. 



300 LAWS OF VARIATION. Chap. XXIV. 

beans (Phaseolus vulgaris]) in a bed were killed except about 
one in thirty, which completely escaped. 69 On the same day oi 
the month, but in the year 1864, there was a severe frost in 
Kent, and two rows of scarlet-runners (P. muUifl&rus) 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 dwarf bean" 
(P. vulgaris*, one single plant escaped. A still more severe 
frost occurred four days afterwards, and of the dozen plants 
which had previously escaped only three survived ; these 
were uot 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 countrv. In mv ' Origin of 
Species ' I have alluded to some cases, and I could add many 
others. One instance must suffice: Mr. G rigor, of Forres, 70 
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 

e9 London's * Gard. Mag.,* vol. xii., pl>nts, which h_- cultivated in 

1836 p. 78. Lnglani along-ii^ specimens from 

:o • Gardener's Chron..' 1 $35. p. 699. northern districts: and he found a 

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

1870, p. S^5) a number of striking hardiness during the winter, but io 

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

d'.iring the summer. 



Chap. XXIV. ACCLIMATISATION. 301 

" beds of the one can he 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 ; bnt such occasionally arise. Thus Loudon 71 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 
purple kinds are a little hardier than the white Cape broccoli, <: but 
" they are not to be depended on after the thermometer falls below 
" 24° Fahr. ;" the Walcheren broccoli is less tender than the Cape, 
and there are several varieties which will stand much severer cold 
than the AValcheren. 72 Cauliflowers seed more freely in India than 
cabbages. 73 To give one instance with flowers : eleven plants raised 
from a hollyhock, called the Queen of the Whites,™ 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. 75 Tew pelargoniums can resist the 
heat of a stove, but Alba 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 Fkur seems as if it had been made on 
" purpose for growing in winter, like many bulbs, and to rest all 
" summer/' 7ti 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- 



71 ' Arboretum ci rruticetum,' vol. 75 'Gardener's Chronicle,' 1841, p. 
lii. p. 1376. 291. 

72 Mr. Robson, in ' Journal of 76 Mr. Beaton, in ' Cottage Gar- 
Horticulture,' 1861, p. 23. rlener,' March 20th, 1860, p. 377. 

73 Dr. Bonavia, 'Keport of the Queen Mab will also stand stove heat. 
Agri.-Hort. Soc. of Oudh,' 1866. See 'Gardener's Chronicle,' 1845, p, 

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

35 



302 LAWS OF VARIATION. Chap. XXTV 

<s seed, one direct from Europe, the other saved at Bangalore (of 
" which the mean temperature is much below that of Madras), were 
il 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." 77 Mr. J. Scott of the Calcutta Botanic Gardens, 
informs me that seeds of the sweet-pea (Lathyrus 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 las 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 A^arieties, 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 owm, 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 
effected 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 country, 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 c ountry 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 Naudin 78 that the races of 
melons, squashes, and gourds, which have long been cultivated 

78 Quote] Lv Asa Gray, in 'Am. Journ. of Sci.,' 2nd series, Jan. 1865, 
p. 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 
directly 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, " Yernaculum peons 
'* peregrine longe praesfantius est." ' 9 

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, bay, 
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-lean has often been advanced as an 

79 For China, see ' Memoire' sur ' Journal do Physique,' torn, xxiv., 
les Chinois,' turn. xi., 1786, p. 60. 1784. 
Columella is Quoted by Carlier, in 



Chap. XXIV. ACCLIMATISATION. 305 

instance of a plant which has not become hardier since its 
first introduction into Britain. We hear, however, on excel- 
lent authority, 80 that some very 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 power of resisting frost ; but no 
one, as far as I can hear, has ever separated such hardy 
seedlings, so as to prevent 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 always 
anxious for as early a crop as possible, would sow their seed 
a few days earlier than formerly. Kow, 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 surprising 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. 

80 Messrs. Hardy and Son, in 'Gard. Chronicle,' 1856, p. £89. 



806 LAWS OF VARIATION. Chap. XXIV. 



Arrests of Development : Rudimentary 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 differ much from 
any normal structure, they require only a passing notice. Thus 
trie 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. 81 

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 preserved. 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." s2 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 ;" s3 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 Desmarest, 54 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 grape with mere traces of seeds, " so 
" small and lying so near the stalk that they are not perceived in 
" eating the grape." M In certain varieties of the gourd, the tendrils, 
according to Xaudin, 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 (Muscari comosum) 
in its natural state the upper and central flowers are brightly 
coloured but rudimentary ; under cultivation the tendency to 



81 Isid.GeoriroySaint-Hilaire.'Hist. 5i « Encyclop. Method.,' 1820, p. 
Nat. des Anomalies,' 1336. torn. ii. 433: see p. 500, on the Inlian zebu 
pp.210, "223. 224-, 395; 'Philosoph. casting its horns. Similar cases in 
Transact.,' 1775. ^ 313. European cattle were given in tL« 

82 Pallas, quoted "by Youatt on third chapter. 

Sheep, p. 25. 85 Pallas, ' Travels,' Eng. Translate 

83 Vouatt on Cattle, 1834, p. 174. vol. i. p. 243. 



Chat. XXIV. ARRESTED DEVELOPMENT AND RUDIMENTS. 307 

abortion travels downwards and outwards, and all the flowers 
become rudimentary ; but the abortive stamens and pistils are not 
so small in the lower as in the upper flowers. In the Viburnum 
onulus, on the other hand, the outer flowers naturally have their 
organs of fructification in a rudimentary state, and the corolla is of 
large size ; under cultivation, the change spreads to the centre, and 
all the flowers become affected. In the connpositse, 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 86 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. 87 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 Composite, a 
tendency to the abortion of the pappus 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, 88 the abortion is only partial in Cartha- 
mus creticus, but more extended in 0. lanatus ; for in this species 
only two or three of the central seeds are furnished with a pappus, 
the surrounding seeds being either quite naked or furnished with a 
few hairs ; and lastly in O. 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 by disuse, and the great reduction of the wings 
in certain silk-moths, with mere rudiments left, has probably been 
aided by disuse. 

With 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 

86 Mr. Beaton, in 'Journal of Hor- 1862, p. 233. 

ticulture,' May 21, 1861, p. 133. 88 'Annales du Museum,' torn, vi 

87 I ecoq, ' De la Fecondation,' p. 319. 



308 LAWS OF VARIATION. Chap. XXIV. 

parts which have become rudimentary under domestication. 
We do hot know through what steps under nature rudimentary 
organs have parsed 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 principle, that of economy of 
growth, will 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 
part 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 
mi triment. 1 1 < >w then can the further reduction of an already 
some what reduced part be effected? That this has occurred 



Chap XXIV. ARRESTED DEVELOPMENT AND RUDIMENTS. 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. Romanes 89 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. With 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 mammae ; but in our domesticated animals, the 
latter occasionally become considerably developed and yield 
milk. The atrophied mammae, 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, 

89 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 com- 

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 VARIATION. Chap. XXIY, 

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. Gr. T. Brown, 
frequently contain minute irregular nodules of bone. These 
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 variation, continued CORRELATED variability. 

EXPLANATION OF TERM CORRELATION" — CONNECTED WITH DEVEOLPMENT 

MODIFICATIONS CORRELATED WITH THE INCREASED OR DECREASED SIZE 
OF PARTS — CORRELATED VARIATION OF HOMOLOGOUS PARTS — FEATHERED 
FEET LN BPRDS ASSUMING THE STRUCTURE 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 
MONSTROSITIES— 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-ordinated 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 VARIATION. Chap. 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 supposing that the original 
cause of the variation was necessarily connected with the 
reproductive organs, or with the age of the affected 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 differs in different 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 apparently 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 development of the same part, as well as of 
other and intimately connected parts. Isidore Geoffroy Saint- 
Hilaire states l that this may constantly be observed with 
monstrosities in the animal kingdom ; and Moquin-Tandon 2 
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 

1 'Hist, des Anomalies,' torn. iii. p. on the Morphology 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, differences • 'Elements de Teratologic Veg., 

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



Chap. XXV. COEEELATED VARIABILITY. 313 

accompanied by deviations of structure in the appended parts. 
We 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 probable that certain modifications in the larvae of 
insects would 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 vertebras 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 
win g-feathers are generally lessened in number. Fantails have 
been selected for their large widely-expanded tails, with nu- 
merous tail feathers, and the caudal vertebras 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 scutelhe 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 highly-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. 3 

3 Prof. J. B. Simonds, on the Age of the Ox, Sheep, &c. quoted in ' Gard 
Chronicle,' 1854, p. 588. 



314 LAWS OF YAEIATIOX. Chap. XXY. 

Correlated Variation of Homologous Parts. — Parts which are 
homologous tend to vary in the same manner; and this is 
what might have been expected, for such 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 
symmetry 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 have 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 homologons, this symmetry often fails, 
as with the varieties of the Antirrhinum or snapdragon, or 
that variety of the kidney-bean (Phaseolus) which has a 
white standard-petal. 

In the Vertebrate 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 Geoffroy 4 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 5 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, 
h ive. according to the excellent authority of Mr. Hewitt, 6 

4 ■ Hist, des Anomalies,' torn. i. p. torn. i. p. 635. 
S74. 6 'The Poultry Book,' by W. B 

4 Quoted by Isid. Geoffroy, ibid., Tegetmeier, 186 p. 250. 



Ckap. XXY. COEEELATED VAEIABILITY. 315 

been seen to exceed the wing-feathers 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. Hence it may be suspected that excess of 
food has first given redundancy to the plumage, and then 
that the law of homologous variation has led to the develop- 
ment of feathers on the legs, in a position corresponding with 
those on the wing, namely, 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. 7 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, but the very same digits which in the wing are 
completely united by 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 8 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 greyhound and mastiff. What a monster a greyhound 
would appear with the head of a mastiff! The modern 
bulldog, however, has fine limbs, but this is a recently-selected 
character. From the measurements given in the sixth 

7 Naturalists differ with respect Lyceum of Nat. Hist, of New York,* 

to the homologies of the digits of vol. x., 1872, p. 16. 

oirds ; but several uphold the view 8 A. Walker on Intermarriage, 

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



316 LAWS OF TAEIATIOX. CiiAP. XXV. 

chapter, we see that in several breeds of the pigeon the length 
of the beak and the size of the feet are correlated. The view 
which, as before explained, 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 AEr. 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 perhaps stands in closer correlation with the develop- 
ment of the corrugated skin or wattle 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 generally accompanied by white 
feet. 9 \Yith 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 different 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. 

9 "The Farrier and Naturalist,' me that about three-fourth- of' whit 9- 
vol. i.. 1828. p. 456. A gentleman laced horses have white legs. 
who has attended to this point, tells 



Chap. XXV. CORRELATED VARIABILITY. 317 

The lopping 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, which have 
been increased by selection during many generations. Now, 
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 clearly seen in " half-lops " 
— that is, in rabbits with only one ear lopping forward — for 
the opposite sides of their skulls were not strictly symmetrical. 
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 result 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 10 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 

10 Godron, ' Sur l'Espece,' torn. ii. p. 217. 



318 LAWS OF VARIATION. Chap. XXV. 

in correlation with, the elongated and reversed feathers on the 

back of the neck, which form the hood. 

The hoofs and hair are homologous appendages; and a 
careful observer, namely Azara, 11 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 12 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 wool, have horns almost like 
those of a goat. Sturm 13 expressly declares that in different 
races the more the wool is curled the more the- horns are 
spirally twisted. We have 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 14 that " only 
' ; the white goats which 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. 15 Those who have tried 
hydropathy are aware that the frequent application of cold 
water stimulates the skin ; and whatever stimulates the skin 

11 ' Quadrupedes du Paraguay,' apt to vary together." Dr. Wilckens 
torn. ii. p. 333. ("Darwin's Theorie," 'Jahibuch 

12 On Sheep, p. 142. der Deutschen Viehzucht,' 1836, 1. 

13 ' L'eber Racen, Kreuzungen." &c, Heft) translates my words into " lang- 
L8'25, s. "-'-4. und grobhaarige Thiere sollen ge- 

14 Quoted from Conolly. in 'The neigter sein, iange und viele Horner 
Indian Field/ Feb. 1859, vol. ii. p. zu bekommen," and he then justly 
266. disputes this proposition; but what I 

15 In the third chapter I have said have really said, in accordance with 
that " the hair and horns are so Uose- the authorities just quoted, may, ] 
ly related to each other, that they arc think, be trusted. 



Chap. XXV. COKEELATED VARIABILITY. 319 

tends to increase the growth of the hair, as is well shown in 
the abnormal growth of hair near old inflamed surfaces. 
Now, Professor Low 16 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 by 
correlation on the horns. The presence or absence of horns^ 
moreover, both in the case of sheep and cattle, acts, as will 
presently be shown, by some sort of correlation on the skull. 
With respect to hair and teeth, Mr. Yarrell 17 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 18 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 women. 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, 

16 'Domesticated Animals of the 17 ' Proceedings Zoolog. Soc.,' 1833 

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

Wilckens argues (' Landwirth. Wo- 18 Sedgwick, ' Brit, and F->rtign 

chenblatt,' Nr. 10, 1869) to the same M'dko-Chirurg. Review/ April, 1868, 

effect with respect to domestic animais p. 453. 
in Germany. 



320 LAWS OF YAEIATIOX. Chap. XXY. 

in those rare cases in which the 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 protection : 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 bristles. I may add, though not strictly 
connected with our present point, that an agriculturist 19 
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 hairy breed.' 3 

In the previous eases 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 20 saw at 
the Burmese Court a man, thirty years old, with his whole 
body, 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 twenty years 
old; and at this period he acquired five teeth in the upper jaw, 
namely, four incisors and one canine, and four incisor teeth in 
the lower jaw ; all the teeth were small. This man had a 
daughter who was born with hair within her ears ; and the 
hair soon extended over her body. When Captain Yule 21 
visited the Court, he found this girl grown ujd ; 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 

19 'Gard. Chronicle.' 1849, p. 2 - 1 • Narrative of a Mission to tht 

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



Chap. XXV. COERELATED 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 fifty-five }'ears old, and of his son, 
with their faces covered with hair, has recently occurred in 
Russia. 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 years 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. ^Ye 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 Bnrmah are as different 
as possible. 22 

Here is another and somewhat different case communicated 
to me by Mr. Wallace on the authority of Dr. Purland, a 
dentist : Julia Pastrana, a Spanish dancer, was a remarkably 
fine woman, but she had a thick mascnline 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 two orders of mammals— namely, the 
Edentata and Cetacea — which are the most abnormal in their 
dermal covering, are likewise the most abnormal either by 
deficiency 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 man and his son, 



322 LAWS OF VARIATION. Chap. XXV 

" lias at tlie' same time met with defective development of 
" the dental system." Certain forms of blindness seem to be 
associated with 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." 23 

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- 
ceptions. The first two notices were published in 1829, and 
relate to English and Persian cats : of the latter, the Eev. W. 
T. Brce 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." 24 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 

23 These statements are taken in cats. Air. Lawson Tait states 
fiom Mr. Sedgwick, in the ' Medico- (-Nature,' 1873, p. 323) thnt only 
Ohirurg. Review,' July, 1861, p. male cats are thus afl'ected ; but this 
j 98; April, 1863, pp. 455 and 458. must be a hasty generalisation. The 
Liebreich is quoted by Professor first case recorded in England by Mr. 
Devay, in his ' Manages Consan- Bree related to a female, and Mr. 
guins,' 1862, p. 116. Fox informs me that he has bred 

24 Loudon's 'Mag. of Xat. Hist.,' kittens from a white female with 
vol. i., 1829, pp. 66, 178. See also blue eyes, which was completely deaf ; 
Dr. P. Lucas, 'L'Hered. Xat.,' torn. i. he has also observed other females it 
p. 428, on the inheritance of deafness the same condition. 



Chap. XXV. CORRELATED VARIABILITY 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 25 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 manj^ 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 any 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 would 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 chiefly 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- 
25 'Annales des Sc. Vat.' Zoolog., 3rd series, 1847, torn. viii. p. 239. 



321 LAWS OF VARIATION. Chap. XXV. 

verted into cornucopias, which 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 purple flowers, a purple mark may be seen on 
the stipules. 

M. Faivre states that with the A'arieties 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 always have voluminous, 
balloon-like calyces. 26 T\ ith other plants the leaves and fruit 
or seeds vary together in coluur, as in a curious pale-leaved 
variety of the sycamore, which has recently been described ia 
France, 27 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. 28 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, 29 
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 
yard 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 have 
contracted flowers : the difference between " Brilliant " and 
its parent " Tom Thumb " is a good instance of this. It may 
be suspected that the curious case described by Ei^so, 30 of a 
variety of the Orange which produces on the young shoots 
rounded leaves with winged petioles, and afterwards elongated 
leaves on long but wingless petioles, is connected with the 

26 'Revue des Cours Scientifiques,' stances, ' Des Variete's,' 1865, p. 72. 
June 5, 1869, p. 430. 29 'Arbres Fruitiers,' 1836, torn. ii. 

a-dener's Chron.,' 1864, p. pp. 204-, 226. 
L202. 30 ' Annales du Museum,' torn, xx 

88 Verlot gives several 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, 31 " 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, 32 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 Geoffroy Saint- Hilaire, in his 
work on Monstrosities, insists, 33 " 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 teeth 
assume a peculiar and characteristic form. Professor Eol- 
leston, also, informs me that the incisor teeth are sometimes 

31 < Gardener's Chron.,' 1843, p. p. 402. See also M. Camille Dareste, 
877. ' Recherches sur les Conditions,' &c, 

32 Ibid., 1845, p. 102. 1863, pp. 16, 48. 
23 'Hist, des Anomalies,' torn. iii. 

36 



326 LAWS OF VARIATION. Chap. XXV. 

furnished with a vascular rim in correlation with intra- 
pulmonaiy 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 pigeons of all breeds, which 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 ? \Yhite 
Pea-fowls, as has been observed both in England and France, 34 
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 foreheads 
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 nasai 
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 steps 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 authors as one of balancement or 
compensation. In the chapter on Fowls, I have shown that 

34 Rev. E. S. Dixon, ' Ornamental Geoffrov, ' Hi<t. Anomalies,' torn. L 
Poultry,' 1848, p. Ill; Isidore p. 211." 



Chap. XXV. CORRELATED VARIABILITY. 327 

with Polish fowls the tuft of feathers was probably at first 
small; 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, aud 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 depressions 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 35 found that the skull of a horn<_d 
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." 36 

It may be well here to pause and observe how the effects 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 

85 ' On the Breeding of Domestic Animals,' 1829, p. G. 
88 Youatt on Cattle, 1884, p. 283. 



328 LAWS OF VARIATION. Chap. XXV. 

vertebrae, with strengthened ligaments ; enlarged dorsal 
vertebrae to support the neck, with powerful 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 multiplying ; 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, by 
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 cise for fleetness and 
in the other for draught. 

Although natural selection would thus 3: tend to give to 

s " Mr. Herbert Spencer ( ; Principles " faculties multiply, and as fast as 

of Biology,' 1864, vol. i. pp. 452, " the number of organs that <x>- 

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 become* 



Chap. XXY. CORRELATED VARIABILITY. 329 

the male elk its present structure, yet it is probable that 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 they 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 skull 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 with 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. 38 
Thus Dr. Bedcloe by his tables shows 39 that a relation exists 
between liability to consumption and the colour of the hair, 
eyes, and skin. It has been aflirmed 40 that, in the French 
army which invaded Russia, soldiers having a dark complexion 
from the southern parts of Europe, withstood the intense 



u less and less capable of producing our domesticated quadrupeds and 

' : specific adaptations ; and remains birds. 

" fully capable only of maintaining 38 Dr. Prosper Lucas apparently 

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

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

natural selection can do little in 39 ' British Medical Journal,' 1862, 

modifying the higher animals sur- p. 433. 

prises me, seeing that man's selection *° Boudin, ' Geograph Medicala, 

has undoubtedly effected much with torn. 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 scorching 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 by 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. Red 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 tracheae, 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 fungus than those producing yellow silk. 

The cases of immunity from the action of certain vegetable 
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 Wynian, of 
all the hogs, excepting those of a black colour, suffering 
severely in Virginia from eating the root of the Lachnanthea 



Chap. XXV. CORRELATED VARIABILITY. 331 

tinetoria. According to Spinola and others, 41 buckwheat (Poly- 
gonum fagopyrum), when in flower, is highly injurious to white 
or white-spotted pigs, if they 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 
white and white- spotted horses being greatly injured by 
eating mildewed and honeydewed vetches ; every spot of skin 
bearing white hairs becoming inflamed and gangrenous. The 
Eev. 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 honeydewed, and 
probably mildewed; the horses, with two exceptions, 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 (JEtluisa cynajpium) 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." 42 With cattle, independently 
of the action of any poison, cases have been published by 
Youatt and Erdt of cutaneous diseases with much consti- 
tutional disturbance (in one instance after exposure to a hot 
sun) affecting every single point which bore a white hair, but 
completely passing over other parts of the body. Similar 
cases have been observed with horses. 43 



41 This fact and the following 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 42 Mr. Mogford, in the ' Veteri- 

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

Settegast Q Die Thierzucht,' 1868, p. 22, 1861, p. 545. 
39) says that white or white-spotted 43 ' Edinburgh Veterinary Jouma* 

sheep sutler like pigs, or even die from Oct. I860, p. 347. 



332 LAWS OF VARIATION. Chap. XXV. 

We tlrus see tliat not only do those parts of the skin which 
bear white hair differ 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 symptoms, 
and even death, to all the white, or white-spotted animals. 



Chap. XXVI. FUSION OF HOMOLOGOUS FARTS. 333 



CHAPTER XXVI. 

LAWS OF VARIATION, continued SUMMARY. 

1HE 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 LNDUCING VARIATION — ANALOGOUS OR PARALLEL 
VARIETIES — SUMMARY OF THE THREE LAST CHAPTERS. 

TJie Fusion of Homologous Parts. — Geoffroy Saint-Hilaire 
formerly propounded -what he called la loi de Vaffinite de soi 
pour soi, which has been discussed and illustrated by his son, 
Isidore, with respect to monsters in the animal kingdom, 1 
and by Moquin-Tandon, with respect to monstrous plants. 
This law seems to imply that homologous parts actually 
attract one another and then unite. No doubt there are 
many wonderful cases, in which such parts become intimately 
fused together. This is perhaps 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, 2 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 capable judges that the homolo- 
gous parts do not attract each other, but that in the words 
of Air. Lowne : 3 "As union takes place before the differentia- 

1 ' Hist, des Anomalies,' 1832, torn. 3 ' Catalogue of the Teratological 
i. pp. 22, 537-556 ; torn. iii. p. 462. Series in the Museum of the R. Coll. 

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



334 LAWS OF VARIATION. Chap. XXVL 

" 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 4 quite decisively against the law of 
soi pour sot, but concludes by saying, " On se rend parfaitement 
" compte de la formation des monstres, si Ton admet que les 
" embryons qui se soudent appartiennent a un meme oeuf ; 
" qu'ils s'unissent en meme temps qu'ils se forment, et que la 
" soudure ne se produitque 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 5 gives a long list of cases, showing how frequently 
homologous parts, such as leaves, petals, stamens, and pistils, 
flowers, and aggregates of homologous parts, such as buds, 
as veil as fruit, become blended, both normally and abnor- 
mally, with perfect symmetry into one another. 

The Variability of Multiple and Homologous Parts. — Isidore 
Geoffroy 6 insists that, when any part or organ is repeated 
many times in the same animal, it is particularly liable to 
vary both in number and structure. ^Vith 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 vertebras 
or teeth, the rays 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. "With 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, 

4 ' Archives de Zoolog. Exper.,' Jan., 6 'Hist, des Anomalies,' torn. iii. 

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

• ' Teratologie Veg.,' 1841, livre iii. 



Ciiap. 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 Growth, or Balancement. — This law, as 
applied to natural species, was propounded by Goethe and 
Geoffroy 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 illustration 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, 7 
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 
Lathy rus aphaca, with its stipules of great size, and its leaves 
reduced to mere threads, which act as tendrils. De Can- 
dolle 8 has remarked that the varieties of Baphanus satims 
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 'Teratologic Veg.,' p. 156. See 1875, p. 202. 
also my book on ' The Movements and 8 'Memoires du Museum,' &c, 

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



336 LAWS OF VARIATION. Chap. XXVL 

Gucurbita pepo which bear large fruit 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 proper 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. 

Mechanical 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 9 
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 10 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 u 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 
difference in the shape both of the seed and corolla, in the 

9 Prichard, ' Phvs. Hist, of Man- series, torn xix. p. 327. 

kind.' 1851. vol. i. p. 324. " ; Comptes Reudus,' Dec. 1864. p 

10 -Aunales des So. Nat.,' 1st 1039. 



Chat. XXVI. RELATIVE POSITION OF PAETS. 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 12 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 ; 
and the shortening results from a peculiar and abnormal state 
of the embryonal cartilages of the bones. 

Relative 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 ; 13 and he adduces, amongst other 
instances, that of Teucrium campanulatum. In another Labiate 
plant grown by me, viz. the Galeohdolon 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 14 gives the names of ten 
varieties flowering 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 



12 " Ueber fotale Rachites," ' Wiirz- 13 < Teratologie Veg.,' p. 192. 

burner Medicin. Zeitschrift/ I860, B. H 'Journal of Horticulture,' July 

i. s. 265. 2nd, 1861, p. 2.53. 



33S LAWS OF VARIATION. Chap. XXVI. 

flowers, the nectary aborts ; all the petals become alike both in shape 
acd 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. 15 

Morren has described 16 a marvellous flask-shaped flower of the 
Calceolaria, nearly four inches in length, which was almost completely 
peloric ; it grew on the summit of the plant, with a normal flower 
on each side; Prof. TVestwood also has described 17 three similar 
peloric flowers, which all occupied a central position on the flower- 
branches. In the Orchideous genus, Phalasnopsis, 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 striae like those on 
the standard-petal. The keel seemed to resist the change more than 
the other petals. Dutrochet has described 18 an exactly similar case 
in France, and I believe these are the only two instances of pelorism 
in the laburnum 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. blasters has briefly described another leguminous 
plant, 19 namely, a species of clover, in which the uppermost 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*, 20 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 
mere 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 



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

tilise with the same pollen the central 17 ' Gardener's Chronicle,' 1866, p. 

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

nium, or of other highly cultivated 1667. p. 211. 

plants, protecting them of course 18 Memoires . . d* Vegetaux,' 

from insects: then to sow the seed 1837, torn. ii. p. 17". 

separately, and observe whether the 19 ' Journal of Horticulture,' July 

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

raried the most. 20 'Xouvelles Archives du Museum, 

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



Cbap. XXVI. KELATIVE POSITION OF PARTS. 339 

" down." 21 I have discussed the connection between pelorism and 
a central position, partly because some few plants are known nor- 
mally to produce 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 22 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 23 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 j3rolification, 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 21 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 

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

Cell.' Eng. tr., 1852, p. 76. 23 'Transact. Linn. Soc.,' vol. xxiii., 

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

1 Journal of Horticulture,' 1861, June 24 ' Die Getreideart.cn,' 1845, s. 208, 

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



340 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 B 

that the Blue Imperial always has a strong tendency to revert to 
its parent-stock, and the reversion " occurs in this manner : the 
u 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 - 6 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 
c; the pod, give eighty per cent, of single flowers/''' Xow 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 manner 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 
that similar characters occasionally make their appearance 
in the several varieties or races descended from fhe 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 ; firstly, 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 reappearance of characters which were 
possessed by a more or less remote progenitor. But these 
two main divisions can often be separated only conjee- 
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, 

25 ; Gardener's Chronicle,' 1850, p. 26 Quoted in ' Gardener's Chiva.,' 

L98. 1866, p. 74. 



Chap. XXVI. ANALOGOUS VARIATION. 341 

hazel, and barberry have given rise to purple-leaved varieties; and 
as Bernhardi remarks, 27 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 offspring 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 like a serpent ; 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. 
\Ye 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 different 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 28 that several 
breeds of cattle are " sheeted/' — that is, have a broad 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 



27 ' Ueber den Begriff der Pfianzen- 28 < Domesticated Animals,' 1845, 

art,' 1834, s. 14. p. 351. 



3-12 LAWS OF VARIATION. 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 afforded 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 ; turbits 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 appearing from reversion. In some domestic varieties 
the wing-bars, instead of being simply black, as in the rock-pigeon, 
are beautifully 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 Phaps chalccptera ; 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. torquatrix and palumhus), 
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. 29 

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 



29 Bechsiein, ' Xaturgeschichte Deutschlands,' Band it., 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 susjject 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 
Gallus lankiva ; 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 species of the genus 
Lepus differ. 

I will only allude to one other case, already discussed. Now 
that we know that the wild 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 immediate wild parent-horse, but to the striped 
progenitor of the whole genus. 



314 LAWS OF YAEIATIOX. Cnxv XXVI 

I have discussed this subject of analogous variation at con- 
siderable length, because it is well known that the varieties 
of one species frequently resemble distinct species — a fact in 
perfect harmony vrith 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 Air. B. D. Walsh 30 has called the '"Law of 
Equable Variability." or. as he explains it. " if any given cha- 
" raeter 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 5 
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 off 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 differ much in 
species of the same genus, and they are highly variable 
u • Proa Entomolog. See. of Philadelphia,' Oct. 1863, p. 213. 



Chap. XXVI. SUMMARY. 345 

in the 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 chapters, 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 scapulas, 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 difference 
between organisms in a state of nature, and under domestica- 
tion, probably is that in the latter case there has not been 



346 LAWS OF VAKIATKW. 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-species, sometimes "become partially redeveloped in our 
domesticated productions. Such rudiments as occasionally 
make their appearance under domestication, seem always to 
be the result of a sudden arrest of development ; nevertheless 
they are of interest, as showing that rudiments are the relics 
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 indivi duals 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 variability, taken in 
its widest sense, when one part varies other parts vary, 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 parts. 
as the tongue and the orifice of the nostrils, tend to vary in the 
same manner. AYhen the whole body increases or decreases 
in size, various parts become modified ; thus, with pigeons 
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 
in the same or in some connected manner, — as in the case of 
Iho right and left sides of the body, and of the front and 
bind 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 



Cuai\ XXVI. SUMMARY. 347 

curly hair have hoofs like those of a mule ; the wool and the 
horns of sheep often vary together ; hairless dogs are deficient 
in their teeth ; men with redundant hair have abnormal teeth. 
either by deficiency or excess. Birds with long wing-feaihers 
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 without 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 sortie 
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 development often 
become fused together. Multiple and homologous organs 
are especially liable to vary in number and probably ic 



348 LA.WS OF VAEIATION. Chap. XXY1 

form. As the supply 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 p^rts 
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 
nisusformativus, which is in fact a remnant of that simple form 
of reproduction, displayed 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- 
tageous changes 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. PliO VISIONAL HYPOTHESIS OF PANGENESIS. 349 



CHAPTEE 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 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 OF 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 laws 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, with 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 
its 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 



350 



PROVISIONAL HYPOTHESIS 



Chap. XXY1L 



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 YYnewell, the historian of the inductive 
sciences, remarks : — " Hypotheses may often be of service to 
v 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 ovules, 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. 1 

In the First Part I will enumerate as briefly as I can the 
groups of facts which seem to demand connection ; but certain 



1 This hypothesis has heen 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, entitle! ' Sulla Darwiniana 
Teoria della Pangenesi, 1869,' of 
which a translation appear.- 1 in 
' Scientific Opinion,' Sept. 29, 1869 
and the succeeding numbers. He 
rejects the hypothesis, but criticises 
it fairly, and 1 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. Bastian 
(• The Beginnings of Life.' 1872. vol. ii. 
p. 98) says that the hypothesis -looks 
•• like a relic of the old rather than a 
" iitting 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 bv 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. Natnrwissen. 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 mav 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. I may, however, 
refer to Dr. Ross' work, • The Graft 
Theory of Disease ; being an appli- 
cation of Mr. Darwin's hypothesis of 
Pangenesis,' 1872, as he gives sevexaJ 
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 fissiparous 
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. 2 It is 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 convinced that the two processes 
are essentially alike. 3 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- 
" raise 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 ; 4 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 

2 Quoted by Paget, 'Lectures on 328) shows that with Annelids the 
Pathology,' 1853, p. 159. distinction that has been made be- 

3 Dr. Lachmann, also, observes tween fission and budding is not a 
(' Annals and Mag. of Nat. History." fundamental one. See, also, Pro- 
2nd series, vol. xix., 1857, p. 231) fessor Clark's work, ' Mind in Nature,' 
with respect to infusoria, that " fissa- New York, 1865, pp. 62, 91. 

" tion and gemmation pass into each 4 See Bonnet. ' (Euvres d'Hist. 

" other almost imperceptibly." Again, Nat..' torn, v., 1781, p. 339, for 

Mr. W. G. Minor ('Annals and Mag. remarks on the budding-out of the 

of Nat. Hist.,' 3rd series, vol xi. p. amputated limbs of Salamanders. 



352 PROVISIONAL HYPOTHESIS Chap. XXYIL 

another way ; for Trembley observed with, the hydra, that 
the reproduction of the head after amputation was checked as 
soon as the animal put forth reproductive gemmae. 5 

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 rejDlaced 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." 6 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 
algge, by which process the contents of two cells unite into a 
single mass capable oi development, apparently gives us the 
first step towards sexual union : and Pringsheim, in his 
memoir on the pairing of Zoospores, 7 shows that conjugation 
graduates into true sexual reproduction. Moreover, the 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 p.^eudova which do not need fertilisation, be dis- 

5 Paget. 'Lectures on Pathology,' bold, " Ueber Parthenogenesis." 'Sit 
1853, p. 108. zungder math. phvs. Classe.' Munich, 

6 Ibid., pp. 152. 164. Nov. 4th, 1871, p. 240. &'<? also Qua* 

7 Translated in 'Annats and Mag. trefa^es. 'Annalesdes Sc. Nat. Zoolog., 
)f Nat. Hist..' April, 1S7«>. p. 272. "~ 3rd Series, 1850, p. 138. 

8 BisehorT, as quoted by von Sie- 



Chap. XXVII. OF PANGENESIS. 353 

tinguished from true ova, as was first shown by Sir J. 
Lubbock, and is now admitted by Siebold. So, again, the 
germ-balls in the larvse of Cecidomyia are said by Leuckart 9 
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 by 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 produced 

9 'On the Asexual Reproduction of 'Annals and M;ig. of Nat. B jst,, 
Cecidomyide Larvae,' translated in March, 1866, pp. 167, 171, 



354 PROVISIONAL HYPOTHESIS Chap. XXVII 

sexually and asexually, -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. 10 Afterwards, they often advance 
in organisation, as we see in the many cases of ki 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 nssiparous generation. Some 
of the lower plants, however, such as mosses and certain alga?, 
according to Dr. L. Eadlkofer, 11 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 fcr ihe 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 

10 Prof. All man speaks (• Transact. ' ; of zooids, that no retrogression ever 

R. Soc of Edinburgh,' vol. xxvi.. 1870, " takes place in the series." 

p. 102) decisively on this head with ll ' Annals and Mag. of Xat. Hist., 

respect to the Hydroida : he says. "It 2nd series, vol. xx., 1857, pp. 153- 

'• is a universal law in the succession 4 55 



Chat. XXYII. 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 sufficient importance to 
account for the first origin of sexual intercourse is extremely 
doubtful." Secondly, I have shown from a large 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. XXVIL 

in the case of the Teredo. 12 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, 13 who proved by numerous experiments, that, 
when a very small number of spermatozoa are applied to the 
ova of Batraehians, they are only partially impregnated, and 
an embryo is never fully developed. 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, 14 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 Xaudin 15 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 whollv excluded; for M. Jourdan 



10 



12 ' Annales des Sc. Nat.,' 3rd series, Weijenbergh also raise! ('Nat are.' 

torn. xiii. I>ee. 21, 1871, i>. l-i-i') two successive 

13 -Transact. Phil. Soc.,' 1851, pp. generations from uuimpregnated fe- 
2 8,210; 1853, pp. 245, 247. males of another lepiiopterous insect, 

14 'Beitrage zur Kenntniss,' &c, Liparis dlspar. These females did 
1S44, s. 345. not produce at most one-twentieth 

15 ; Xouvelles Archives du Mu- of their full complement of eggs, and 
;eura.' torn. i. p. 27. many of the eggs were worthless. 

16 As quoted by Sir J. Lubbock in Moreover the caterpillars raise 1 from 
'Nat. Hist. Peview ' 1862, p. 345. these unfertilised eggs ; ' possessed far 



Chap. XXVII. OF PANGENESIS. . 357 

found that, out of about 58,000 eggs laid by unimpregnated 
silk-motlis, many 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 Haeckel 17 
found that by cutting the segmented and fertilised ova or 
larvae of Siphon ophor* (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. The 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. 

Re-growth of amputated parts. — This subject deserves a little 
further discussion. A mmltitude 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, 18 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- 18 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, ' (Euvres 

yielded a caterpillar. d'Hist. Nat.,' torn, v., part i., 4to. 

17 * Entwickelungsgeschichte der edit., 1781, pp. 343, 350. 
Siphonophora,' 1869, p. 73. 



358 PROVISIONAL HYPOTHESIS Chap. XXVII 

amputated it was replaced "by a perfect limb. 19 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 Amblystoma lurida, three toes are first 
developed, then the fourth, and on the hind-feet the fifth, 
and so it is with a reproduced limb. 20 

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 larvaa or tadpoles of the 
Batrachians are capable of reproducing lost members, but 
not so the adults. 21 Mature insects have no power of re- 
growth, excepting in one order, whilst the larvae 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 Xemerteans, 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.' 22 

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, 23 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 
dew, is that the terrestrial salamander, according to Lessona, 
jannot reproduce lost parts, whilst another species of the 

19 Vulpian, as quoted by Prof. this member, it was asserted, had 

T aivre, ' La Variability des Especes,' been thrice reproduced ; having been 

1868. p. 112. lost, I presume, each time by disease. 

-° Dr. P. Hoy, ' The American Xatu- Sir J. Paget informs me that he feels 

ralist,' Sept. 1871, p. 579. some doubt about the facts recorded 

21 Dr. Giinther, in Owen's ' Ana- by Sir J. Simpson (' Monthly Journal 
tomy of Vertebrates,' vol. i., 1866. p. of Medical Science,' Edinburgh, 1848, 
567. Spallanzani has made similar new series, vol. ii. p. 890) of the re- 
observations, growth of limbs in the womb in the 

22 A thrush was exhibited before case of man. 

v .he British Association at Hull, in 23 ' Atti della Soc. Ital. di Sc. Xat., 

1853, which had lost its tarsus, and vol. si., 1869, p. 493. 



Chap. XXTII. OF PANGENESIS. 359 

same genns, 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. 24 Even with the aquatic salamander 
the capacity is to a certain extent localised, for when M. 
Philipeaux, 25 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; 26 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, Diajjheromera 
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 capacity is localised (as in 
the case of the salamander), for Dr. Scudder found, 27 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. 

24 Lessona states that this is so in v. p. 294, as quoted by Prof. Rolleston 
thi! paper just referred to. See also in his remarkable address to the 30th 
* The American Naturalist,' Sept. annual meeting of the British Medical 
1871, p. 579. Association. 

25 ' Comptes Rendus,' Oct. 1, 1866, 27 ' Proc. Boston Soc. of Nat. Hist, 
and June, 1867. vol. sii., 1868-69, p. 1. 

26 Bonnet, ' (Euvres Hist. Nat.,' vol. 



S60 PEOYISIONAL HYPOTHESIS Chap. XXYIL 

Graft-hybrids. — 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. Xor 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 bnd on the 
same plant being in the least degree affected. We may there- 
fore infer, in accordance with the common view, that each 
bnd 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 
buing 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 strives 



Chap. XXYII. 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. We 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 
cjuagga 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, 28 there 
is an Ephemerous insect which moults above twenty times, 
undergoing each time a slight but decided change of structure ; 
and these changes, as he further remarks, probably reveal to 

28 ' Transact. Linn. Soc.,' vol. xxiv., 1863, p. 62. 



362 PROVISIONAL HYPOTHESIS Chap. XXVII. 

ns 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 hew and distinct 
' ; developmental process," &c. 29 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 different parts of the body ; 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. The 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. 30 

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 

C9 'Parthenogenesis.' 1849, pp. 25, graduates into gemmation or zoid- 

2»3. 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 30 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. 



Chap. XXVIL OF PANGENESIS. 363 

parent-form, as with the larvae of Cecidomyia, or may differ 
to an astonishing degree, as with many parasitic worms and 
jelly- fishes; bnt 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 group 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 Peneus under the 
iS auplius-form ; and how wonderfully these larval forms differ 
from one another, is known to every naturalist. 31 Somo 
other crustaceans, as the same author observes, start from the 
same point and arrive at nearly the same end, but in the 

31 Fritz Miiller's ' Fur Darwin,' Nat.,' 2nd series, Zoolog., torn. iii. p. 

1864, s. 65, 71. The highest 322) on the differenced the meta- 

authority on crustaceans, Prof. Milne- morphosis of closely-allied genera. 
Edwards, insists ('Annal. des Sci. 



S64: PROVISIONAL HYPOTHESIS Chap. XXVII. 

middle of their development are widely different from one 
another. Still more striking cases could be given with 
respect to the Echinodermata. With the Medusas or jelly- 
fishes Professor Allnian 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 polypoids ; 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 
'•Hydroiche any phase, planuloid, polypoid, or medusoid, may 
" be absent." 32 

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. 

The Functional Independence of the Elements or Units of the 
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, 33 has its proper life, its autonomy ; it can develop 
and reproduce itself independently of the adjoining tissues. 
A great German authority, Yirchow, 34 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 
v - performance of duties Every single epithelial and 

32 Prof. Allman, in ' Annals and bv Sars. 
Mag. of Nat. Hist.,' 3rd series, vol. " 33 ' Tissus Vivants,' 1866, p. 22. 

xiii., 1864-, p. 343; Dr. S. Wright, 34 '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. 



Cliap. xxyii. of pangenesis. 365 

"muscular fibre-cell leads a sort of parasitical existence in 

11 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. 35 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 36 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 bo 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 
length of twenty-four centimetres, or about nine inches ; so 
that the head of the ox appeared to bear three horns. 37 The 
tail of a pig has been grafted into the middle of its back, and 
reacquired sensibility. Dr. Oilier 38 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. The frequent presence of hairs and of per- 
fectly developed teeth, even teeth of the second dentition, in 
ovarian tumours, 39 are facts leading to the same conclusion. 

35 Paget, ' Surgical Pathology,' des Os,' p. 8. 

Tol. i., 1853, pp. 12-14. 3D Isidore Geoffroy Saint-Hilaire, 

36 Ibid., p. 19. 'Hist, des Anomalies,' torn. ii. pp. 

37 See Prof. Mantegazza's interest- 549, 560, 562 ; Virchow, ibid., p. 
ing work, ' Degli innesti Animali,' &c, 484. Lawson Tait, ' The Pathology of 
Milano, 1865, p. 51, tab. 3. Diseases of the Ovaries,' 1874, pp. 61, 

88 'De la Production Artificielle 62. 



dob PROVISIONAL HYPOTHESIS Chap. XXVII. 

Mr. Lawson Tait refers to a tumour in which "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. 40 The doctrine of omnis celhda e cellidd is admitted 
for plants, and widely prevails with respect to animals. 41 
Thus Yirchow, 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. 

Variability 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 41 Dr. W*. Turner. 'The Present 

of cells, see Ernst Hackel's ' Generelle Aspect of Cellular Pathology,' ' Edin« 
Morpholog.,' Baud ii., 186(3, s. 275. burgh Medical Journal.' April, 18fi3. 



Chap. XXYII. OF PANGENESIS. 367 

generally from changed conditions acting during successive 
generations. The fluctuating variability thus induced is ap- 
parently clue 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 
offspring. 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 would 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, 



363 PROVISIONAL HYPOTHESIS Chap. XXVIL 

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 
non-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 any 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 powers in some 
cases are even antagonistic, for each acts alternately in suc- 
cessive generations. Eeversion 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. AYe 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. XXYII. 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 Scrophulariaceee. 
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 



o/O PROVISIONAL HYPOTHESIS Chap. XXVII 

substances 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 which I have called 
Pangenesis. Views in many respects similar have been pro- 
pounded by various authors. 42 

42 Mr. G. H. Lewes (• Fortnightly tially different, Buiinet ( ; (Euvres 
Renew,' Nor. 1, 1 868. p. 506) remark's d'Hist. Nat./ torn, 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- 
tion 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 tho^e within buds 
held by Hippocrates and others. Ray, and the sexual organ? is not clear. 
in his ' Wisdom of God ' (2nd-edit., Prof. Owen says (' Anatomy of Verte- 
1692, p. Si), says that "every part brates,' vol. iii., 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 Buff'on ("Hist. Nat. pounded in his 'Parthenogenesis' 
Gen.,' edit, of 1749, torn. ii. pp. 54-. 62, (1849, pp. 5-8), and which he now con- 
329, 333, 420, 425) appear at first si ders as erroneous, and my hypothesis 
sight to be the same as the gemmules of pangenesis : but a reviewer (' Jour- 
•f my hypothesis, but they are essen- nal of Anat. and Phys.,' May, 1869, 



Char XXYII. OF PANGENESIS. 371 

Before proceeding to show, firstly, how 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. 
Hsot 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 (' Nuova Antologia, Maggio,' 

Spencer ( : Principles of Biology,' vol. 1868), that he (in his 'Elementi di 

L, 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 thi^ is not the case. 



372 PROVISIONAL HYPOTHESIS Chap. XXVU. 

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. 43 

But I have further to assume that the gemmules in their un- 
developed state are capable of largely 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 44 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. JSor does the extreme 
minuteness of the gemmules, which can hardly differ much in 
nature from the lowest and simplest organisms, render it 
improbable that they should grow and multiply. A great 
authority, Dr. Beale, 43 says " that minute yeast cells are 
" capable of throwing off buds or gemmules, much less than 
" the touVou of an inch in 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. 46 It has recently been ascertained 47 that a minute 
portion of the mucous discharge from an animal affected with 

43 Mr. Lowne has observed (' Jour- 44 'Annales des Sc. Nat.,' 3rd 

nil of Queckett Microscopical Club,' series, Bot., torn. xiv., 1850, p. 244. 
Sept. 23, 1870) certain remarkable 4i ' Disease Germs,' p. 20. 

changes in the tissues of the larva of i6 See some very interesting papers 

a rly. which makes him believe ;< it on this subject by Dr. Beale, in 

" possible that organs and organisms ' Medical Times and Gazette,' Sept. 

" are sometimes developed by the 9th, 1865, pp. 273, 330. 
" aggregation of excessively minute 47 Third Report of the R. Comm 

k ' gemmules, such as those which Mr on the Cattle Plague, as quoted in 

" Darwin's hypothesis demandt." • Gard. Chronicle,' 1866, p. 446. 



Chap. XXYII. 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 undeveloped 
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 within each spermatozoon or pollen- 
grain, and as some animals and plants produce an astonishing 
number of pollen-grains and ovules, 48 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 ordinary 
substance, this difficulty with respect to the gemmules is not 
insuperable. Fiom the data arrived at by Sir W. Thomson, 
my son George finds that a cube of 17 | M of an inch of glass 
or water must consist of between 16 million millions, and 1 31 
thousand million million molecules. No doubt the molecules 
of which an organism is formed are larger, from being more 
complex, than those of an inorganic substance, and probably 

48 Mr. F. Buckland found 6,867,840 seeds in a capsule of an Acropera 
i;ggs in a cod-fish ('Land and Water,' and found the number to be 371,250. 
1868, p. 62). An Ascaris produces Now this plant produces several 
about 64,000,000 eggs (Carpenter's flowers on a raceme, and many ra- 
'Comp. Phys.,' 1854, p. 590). Mr. J. cemes during a season. In an allied 
Scott, of the Royal Botanic Garden genus, Gongora, Mr. Scott has seen 
of Edinburgh, calculated, in the same twenty capsules produced on a single 
manner as I have done for some raceme ; ten such racemes on the 
British Orchids ('Fertilisation of Acropera would yield above seventy- 
Orchids,' p. 344), the number of four mdlions of seed. 

38 



374 PROVISIONAL HYPOTHESIS Chap. XXVIL 

many molecules go to the formation of a genramle ; but when we 
"bear in mind that a cube of - l0 l 00 of an 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 be 
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 are 
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 Composite 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, 49 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 
£ha case of ordinary reproduction that such slight differentia- 

49 Paget, ' Lectures on Pathology,' Tissus Vivants,' pp. 177, 210, 337; 

p. 27 ; Virchow, ' Cellular Patho- Miilier's ' Physiology,' Fng. translat., 

fogy/ translat. bv Dr. Chance, pp. p. 290. 
123, 126, 294- Claude Bernard, ' Des 



376 PROVISIONAL HYPOTHESIS Chap. XXV EL 

fcion 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 vre have been able by the aid of cur 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 off its gemniules, 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. Nor 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. 50 

That the same cells or units may live for a long period and 

50 Prof. Ray Lankester has dis- parative Longevity in Man and the 

cussed several of the points here Lower Animals,' IS70, pp. 3 J, 77, 

referred to as beariLg <>n pangenesis, &c. 
ia his interesting e.-;sav. • On Com- 



Chap. XXYII. OF PANGENESIS. 377 

continue multiplying without being modified by their union 
with free gemmules of any 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. 51 We shall appreciate this difficulty by 
calling to mind what complex yet symmetrical growths the 
cells of plants yield when inoculated by the poison of a 
gall-insect. With animals various polypoid excrescences and 
tumours are generally admitted 52 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 Virchow remarks, 53 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 may 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. 

51 Dr. Ross refers to this subject trans, by Dr. Chance, 1860, pp. GO, 
in his ' Graft Theory of Disease,' 1872, 162, 245, 441, 454. 

p. 53. 53 Ibid., pp. 412-426. 

52 Virchow, ' Cellular Pathology,' 



378 PEO VISIONAL HYPOTHESIS 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 
genmmle. 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 genmrales, 
according to our hypothesis, must have been thrown off 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 ceil 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. 54 

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, we 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 between 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 individuals, the 

M See some good criticisms on this Lewos in the 'Fortnightly Review, 
head by Delpino, and by Mr. G. H. Nov. 1, 1868, p. 509. 



Chap. XXVII. OF PANGENESIS. 379 

wonder would be 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 
stigmatic 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 
micropyle of the egg. 

The antagonism which has long been observed, 55 with 
certain exceptions, between growth and the power of sexual 
reproduction 56 — 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. 

55 Mr. Herbert Spencer (' Princi- of a medusa, with its reproductive 
pies of Biology,' vol. ii. p. 430) has organs active, which produces by 
fully discussed this antagonism. budding a widely different form of 

56 The male salmon is known to medusa ; and this latter also has the 
breed at a very early age. The power of sexual reproduction. Krohn 
Triton and Siredon, whilst retaining has shown (' Anuals and Mag. of 
their larval branchiae, according to Nat. Hist.,' 3rd series, vol. xix., 1862, 
Filippi and Dumeril ('Annals and p. 6) that certain other medusa;, 
Mag. of Nat. Hist.,' 3rd series, 1866, whilst sexually mature, propagate 
p. 157), are capable of reproduction. by gemmae. See, also, Kolliker, 
Ernst Haeckel has recently (' Monats- ' Morphologie und Entwickelungsge- 
berioht Akad. Wiss. Berlin,' Feb. 2nd, schichte des Pennatulidenstammes,' 
1865) observed the surprising case 1872, p. 12. 



380 PEOYISIOXAL HYPOTHESIS Chap. XXVII. 

Hardly any fact in physiology 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 have 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 polarity of the molecules is the efficient cause, and in the 
other 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. 
Thus 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. Nevertheless, the organ- 
isms operated on or multiplying 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. XXVII. OF PANGENESIS. 381 

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 
leason 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 PKOYTSTONAL HYPOTHESIS Chap. XXV1L 

sexual elements agree in power, in accordance with, the view 
that both include the same geninmles. 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, 57 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 land, and thus 
separate themselves into distinct stripes or blotches; and 
reasons were given, when discussing in the fifteenth chapter 
the incompatibility of certain characters to unite, for believing 
in such mutual affinity. ^Yhen 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. 

AY hen two distinct species are crossed, it is notorious that 
they do not yield 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 

17 See his excellent discussion on this subject in ' Xouvelles Archives di 
Museum,' torn. i. p. 151. 



Chap. XXVII. OF PANGENESIS. 383 

between a host of gemnmles 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 develo23ed at a 
spot where no eye previously existed. We have also seen 



3S4 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 
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. XXYII. OF PANGENESIS. 385 

nascent cells, together with the superabundance 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 58 of a 
monstrous chicken with a perfect additional right 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. Yalentin injured the caudal 
extremity of an embryo, and three days afterwards it 
produced rudiments of a double pelvis and of double hind- 
limbs. 59 AYhen frogs, toads, &c, are born with their limbs 
doubled, as sometimes happens, the doubling, as Gervais 
remarks, 60 cannot be due to the complete fusion of two 
embryos, with the exception of the limbs, for the larvae are 
limbless. The same argument is applicable 61 to certain 
insects produced with multiple legs or antennas, for these are 
metamorphosed from apodal or antennas-less larvae. Alphonse 
Milne-Edwards 62 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 63 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 64 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 l'Homme,' &c, 1862, p. 129. 
republished in ' Scientific Opinion,' e2 Giinther's ' Zoological Record, 
Nov. 10, 1869, p. 488. 1864, p. 279. 

59 Todd's 'Cyclop, of Anat. and 63 Sedgwick, in ' Meiico-Chirurg. 
Pliys.,' vol. iv., 1849-52, p. 975. Review,' April, I860, p. 454. 

6 "° ' Compte Rendus,' Nov. 14, 1865, , 64 Isid. Geoffroy Saint-Hilaire, 

p. 800. 'Hist, des Anomalies,' torn i., 1832 

61 As previously remarked by pp. 435, 657 ; and torn. ii. p. 560 
Quatrefages, in his ' Metamorphoses 



883 PROVISIONAL HYPOTHESIS Chap. XXVIL 

Hairs occasionally appear in strange situations, as "'within 
the substance of the brain.'"' 65 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 Sevastopol 
goose, barbnles are developed on the divided filaments of the 
shaft. Imperfect nails sometimes appear on the stumps of 
the amputated fingers of man ; 66 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 the 
phalanges first disappear, " the nails becoming transferred to 
" their proximal remnants, or even to parts which are not 
' ; phalanges." 67 

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 Yicia 
saliva replaced by a tendril ; and a tendril possesses many 
peculiar properties, such as spontaneous movement and irrita- 
bility. The calyx 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 deseiwing 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, 

65 Virchcw, ' Cellular Pathology,' to me. 

66. 67 Dr. Flirbringer, 'Die Knochen 

66 'Muller'sPhys.,' Eng. Translat., etc. bei den schlangenahnlichen 
vol. i., 1833, p. 407. A case of this Sauriern.' as reviewed in 'Journal of 
kind has lately been communicated Anat. and Phys.,' May, 1870, p. 286. 



Chap. XX Y1I. 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. Numerous analogous facts could be given. 68 

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 varying, 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 any 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 particu- 
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, 

68 Moquin - Tandon, ' Teratologic 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. XX VII. 

such as an additional limb or an antenna, springs from a false 
position, it is only necessary that the few first gemmnles 
should he wrongly attached ; for these whilst developing 
would attract other gemmules in due succession, as in the 
re-growth of an amputated limb. When parts which are 
homologous and similar in structure, as the vertebras of 
snakes or the stamens of polyandrous 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 easily 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- 



Chxp. xxvu. 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 gemmules. 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 system, 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 ; 69 and this implies, accord- 
ing to our hypothesis, that gemmules derived from modified 
nerve-cells are transmitted to the offspring. 

It is generall}' 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 

69 See some remarks to this effect by Sir H. Holland in his ' Medical 
Notes,' 1839, p. 32. 



390 PROVISIONAL HYPOTHESIS Chap. XXVIL 

should he 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, phloxes 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. 70 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 
geminules. 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 different geminules. 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 hypo- 
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, 

7e This is the view taken by Prof. elterlichen und im kindlichen Orga- 

fiaeckel, in his ' Generelle Morpho- nismus, die Theilung dieser Materie 

logie' (B. ii. s. 171), who says: bei der Fortpflanzung, ist die Ursache 

" Lediglich die partielle Identitat der der Erblichkeit." 
specifisch constituirten Mateide 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 
gemniules multiply and are transmitted during a long series 
ot 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-Seqvtard 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 with 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 microscopically 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 principle 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 cine 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 which 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 Air. 
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 with 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 
8ides 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, however 
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 by 



Chap. XXVII. 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 pangenesis, 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 hybrids 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, perhaps, 
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. 71 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. Fur instance, when black and white 
pigeons, or black and white fowls, are crossed,— colours which 

71 In these remarks I, in fact, species which are crossed. See his 
follow Natidin, who speaks of the excellent memoir in the ' Nouvelles 
elements or essences of the two Archives du Museum,' torn. i. p. 151. 



396 PROVISIONAL HYPOTHESIS Chap. XXYII. 

do not readily blend. — blue plumage in the one ease, evidently 
derived from the rock-pigeon, and red plumage in the other 
ease, 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 
gTeat classes of facts just discussed, no doubt is extremely 
complex, but so are the facts. The chief assumption is that 



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 
kind is present in the tissues of plants, which is capable of 
combining with that included in another individual, and of 
reproducing every unit of the "whole organism. But we have 
further to assume that the gemmules grow, multiply, and 
aggregate 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 thrown 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 
difficulties. 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 
39 



398 PROVISIONAL HYPOTHESIS Chap. XXVH. 

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 reproductive 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 inolude 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 corresponding 
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- 



Oiup. XXTIT. OF PANGENESIS. 399 

cellular organism. Eeversion depends on the transmission 
from the forefather to his descendants of dormant gemmnles, 
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. No 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. 



£00 CONCLUDING REMARKS. Ciulp. XXVIIL 



CHAPTER XXVIIL 

CONCLUDING REMARKS. 

DOMESTICATION — NATURE AND CAUSES OF VARIABILITY — SELECTION — DIVER- 
GENCE AND DISTINCTNESS OF CHARACTER EXTINCTION OF RACES— 

CTRCEMSTANCES FAVOURABLE TO SELECTION BY MAN — ANTIQUITY OP 
CERTAIN RACES — THE QUESTION WHE