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The Variation of Animals and Plants under Domestication by Charles Darwin

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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. (18/109. Godron 'De l'Espece'
tome 2 page 106; Herbert on Crocus in 'Journal of Hort. Soc.' volume 1 1846
page 254: Dr. Wight, from what he has seen in India, believes in this view;
'Madras Journal of Lit. and Science' volume 4 1836 page 61.) 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 ascend mountains beyond the height at which
they can produce seed. (18/110. Wahlenberg specifies eight species in this
state on the Lapland Alps: see Appendix to Linnaeus 'Tour in Lapland'
translated by Sir J.E. Smith volume 2 pages 274-280.) Certain species of Poa
and Festuca, when growing on mountain-pastures, propagate themselves, as I
hear from Mr. Bentham, almost exclusively by bulblets. Kalm gives a more
curious instance (18/111. 'Travels in North America' English translation
volume 3 page 175.) 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 accidentally 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 calamus extends over a large portion of the
globe, but so rarely perfects fruit that this has been seen only by a few
botanists; according to Caspary, all its pollen-grains are in a worthless
condition. (18/112. With respect to the ivy and Acorus see Dr. Broomfield in
the 'Phytologist' volume 3 page 376. Also Lindley and Vaucher on the Acorus
and see Caspary as below.) 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 nummularia, which is furnished with long runners, so
seldom produces seed-capsules, that Prof. Decaisne (18/113. 'Annal. des Sc.
Nat.' 3rd series Zool. tome 4 page 280. Prof. Decaisne refers also to
analogous cases with mosses and lichens near Paris.), who has especially
attended to this plant, has never seen it in fruit. The Carex rigida often
fails to perfect its seed in Scotland, Lapland, Greenland, Germany, and New
Hampshire in the United States. (18/114. Mr. Tuckermann in Silliman's
'American Journal of Science' volume 65 page 1.) The periwinkle (Vinca minor),
which spreads largely by runners, is said scarcely ever to produce fruit in
England (18/115. Sir J.E. Smith 'English Flora' volume 1 page 339.); but this
plant requires insect-aid for its fertilisation, and the proper insects may be
absent or rare. The Jussiaea grandiflora has become naturalised in Southern
France, and has spread by its rhizomes so extensively as to impede the
navigation of the waters, but never produces fertile seed. (18/116. G.
Planchon 'Flora de Montpellier' 1864 page 20.) The horse-radish (Cochleria
armoracia) spreads pertinaciously and is naturalised 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. (18/117. On
the non-production of seeds in England see Mr. Crocker in 'Gardener's Weekly
Magazine' 1852 page 70; Vaucher 'Hist. Phys. Plantes d'Europe' tome 1 page 33;
Lecoq 'Geograph. Bot. d'Europe' tome 4 page 466; Dr. D. Clos in 'Annal. des
Sc. Nat.' 3rd series Bot. tome 17 1852 page 129: this latter author refers to
other analogous cases. See more especially on this plant and on other allied
cases Prof. Caspary "Die Nuphar" 'Abhand. Naturw. Gesellsch. zu Halle' b. 11
1870 page 40, 78.) Other cases analogous with the foregoing could be given;
for instance, some kinds of mosses and lichens have never been seen to
fructify in France.

Some of these endemic and naturalised plants are probably rendered sterile
from excessive multiplication by buds, and their consequent incapacity to
produce and nourish seed. But the sterility of others more probably depends on
the peculiar conditions under which they live, as in the case of the ivy in
the northern part 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

Finally, the high degree of sterility which often accompanies 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 which connects together all the
foregoing facts and brings them within our present subject, is, that changed
and unnatural conditions of life first give a tendency to sterility; and in
consequence of this, the organs of reproduction being no longer able fully to
perform their proper functions, a supply of organised matter, not required for
the development of the seed, flows either into these organs and renders them
foliaceous, or into the fruit, stems, tubers, etc., increasing their size and
succulency. But it is probable that there exists, independently of any
incipient sterility, an antagonism between the two forms of reproduction,
namely, by seed and buds, when either is carried to an extreme degree. That
incipient sterility plays an important 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 (18/118. 'Bastarderzeugung' s. 565. Kolreuter
'Dritte Fortsetzung' s. 73, 87, 119) also shows that when two species, one
single and the other double, are crossed, the hybrids are apt to be extremely
double.) affirms, 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 (18/119. 'Teoria della
Riproduzione Veg.' 1816 page 73.) first become double. Again, Gartner (18/120.
'Bastarderzeugung' s. 573.) 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 Cucurbitaceae; so that the production of fruit by plants
rendered sterile through any cause is intelligible. Kolreuter has also
expressed his unbounded astonishment at the size and development of the tubers
in certain hybrids; and all experimentalists (18/121. Ibid s. 527.) 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, and in some cases largely-developed organs of vegetation,
etc., are the indirect results--these results having been in most cases
largely increased through continued selection by man.




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 acquired. 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 separating 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-continued 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,
however, mongrels have retained a uniform character from their first

When two varieties are allowed to cross freely, and one is much more numerous
than the other, the former will ultimately 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 conditions 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 discrimination, some degree of
unmethodical selection would likewise 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 has often been supposed, the character of
the offspring in future times; although in some cases it probably has had a
considerable effect.

Domestication, as a general rule, increases the prolificness of animals and
plants. It eliminates the tendency to sterility 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, pigs etc., are
almost certainly descended from aboriginally distinct stocks, and as these
races are now fully fertile together, or at least incomparably more fertile
than most species when crossed, we may with entire confidence accept this

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
reproductive system. Certain plants whilst growing under their natural
conditions, others when cultivated, and others of hybrid origin, are
completely self-impotent, though perfectly healthy; and such plants can be
stimulated to fertility only by being crossed with other individuals of the
same or of a distinct species.

On the other hand, long-continued close interbreeding between the nearest
relations diminishes the constitutional vigour, size, and fertility of the
offspring; and occasionally leads to malformations, but not necessarily to
general deterioration 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 interbreeding
rests to a certain extent on the experience of practical breeders, 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 impunity by the
selection of the most vigorous and healthy individuals; but sooner or later
evil follows. The evil, however, comes on so slowly and gradually that it
easily escapes observation, but can be recognised by the almost instantaneous
manner in which size, constitutional vigour, and fertility are regained when
animals that have long been interbred are crossed with a distinct family.

These two great classes of facts, namely, the good derived from crossing, and
the evil from close interbreeding, with the consideration of the innumerable
adaptations throughout nature for compelling, or favouring, or at least
permitting, the occasional union of distinct individuals, taken together, lead
to the conclusion that it is a law of nature that organic beings shall not
fertilise themselves for perpetuity. This law was first plainly hinted at in
1799, with respect to plants, by Andrew Knight (19/1. 'Transactions Phil.
Soc.' 1799 page 202. For Kolreuter see 'Mem. de l'Acad. de St.-Petersbourg'
tome 3 1809 published 1811 page 197. In reading C.K. Sprengel's remarkable
work, 'Das entdeckte Geheimniss' etc. 1793, it is curious to observe how often
this wonderfully acute observer failed to understand the full meaning of the
structure of the flowers which he has so well described, from not always
having before his mind the key to the problem, namely, the good derived from
the crossing of distinct individual plants.) and, not long afterwards, that
sagacious observer Kolreuter, after showing how well the Malvaceae are adapted
for crossing, asks, "an id aliquid in recessu habeat, quod hujuscemodi flores
nunquam proprio suo pulvere, sed semper eo aliarum su speciei impregnentur,
merito quaritur? 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 innumerable contrivances, which favour crossing, is of the greatest
weight. The most important result of this law is that it leads to uniformity
of character in the individuals of the same species. In the case of certain
hermaphrodites, which probably intercross only at long intervals of time, and
with unisexual animals inhabiting somewhat separated localities, which can
only occasionally come into contact and pair, the greater vigour and fertility
of the crossed offspring will ultimately tend to give uniformity of character.
But when we go beyond the limits of the same species, free intercrossing is
barred by the law of sterility.

In searching for facts which might throw light on the cause of the good
effects from crossing, and of the evil effects from close interbreeding, we
have seen that, on the one hand, it is a widely prevalent and ancient belief,
that animals and plants profit from slight changes in their condition of life;
and it would appear that the germ, in a somewhat analogous manner, is more
effectually stimulated by the male element, when taken from a distinct
individual, and therefore slightly modified in nature, than when taken from a
male having the same identical constitution. On the other hand, numerous facts
have been given, showing that when animals are first subjected to captivity,
even in their native land, and although allowed much liberty, their
reproductive functions are often greatly impaired or quite annulled. Some
groups of animals are more affected than others, but with apparently
capricious exceptions in every group. Some animals never or rarely couple
under confinement; some couple freely, but never or rarely conceive. The
secondary male characters, the maternal functions and instincts, are
occasionally affected. With plants, when first subjected to cultivation,
analogous facts have been observed. We probably owe our double flowers, rich
seedless fruits, and in some cases greatly developed tubers, etc., 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 breeding at different
seasons, by great difference in size, or by sexual preference. But the
crossing of varieties, far from 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 undoubtedly must be ranked as varieties, yield fewer seeds when crossed
than is natural to the parent-species. Other varieties have had their
reproductive powers so far modified that they are either more or less fertile
than their parents, when crossed with a distinct species.

Nevertheless, the fact remains indisputable that domesticated varieties, of
animals and of plants, which differ greatly from one another in structure, but
which are certainly descended from the same aboriginal species, such as the
races of the fowl, pigeon, many vegetables, and a host of other productions,
are extremely fertile when crossed; and this seems to make a broad and
impassable barrier between domestic varieties and natural species. But, as I
will now attempt to show, the distinction is not so great and overwhelmingly
important as it at first appears.


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


The laws governing the production of hybrids are identical, or nearly
identical, in the animal and vegetable kingdoms.


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
complete 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.


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.


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.


The degree of sterility of first crosses and of hybrids runs, to a certain
extent, parallel with the general or systematic affinity of the forms which
are united. For species belonging 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
apparently depends exclusively on the sexual constitution of the species which
are crossed; or on their sexual elective affinity, i.e. Wahlverwandtschaft of
Gartner. As species rarely or never become modified in one character, without
being at the same time modified in many characters, and as systematic affinity
includes all visible similarities and dissimilarities, any difference in
sexual constitution between two species would naturally stand in more or less
close relation with their systematic position.


The sterility of species when first crossed, and that of hybrids, may possibly
depend to a certain extent on distinct causes. With pure species the
reproductive organs are in a perfect condition, whilst with hybrids they are
often plainly deteriorated. A hybrid embryo which partakes of the constitution
of its father and mother is exposed to unnatural conditions, as long as it is
nourished within the womb, or egg, or seed of the mother-form; and as we know
that unnatural conditions often induce sterility, the reproductive organs of
the hybrid might at this early age be permanently affected. But this cause has
no bearing on the infertility of first unions. The diminished number of the
offspring from first unions may often result, as is certainly sometimes the
case, from the premature death of most of the hybrid embryos. But we shall
immediately see that a law of an unknown nature apparently exists, which leads
to the offspring from unions, which are infertile, being themselves more or
less infertile; and this at present is all that can be said.


Hybrids and mongrels present, with the one great exception of fertility, the
most striking accordance in all other respects; namely, in the laws of their
resemblance to their two parents, in their tendency to reversion, in their
variability, and in being absorbed through repeated crosses by either parent-

After arriving at these conclusions, I 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. (19/2. My observations 'On the Character and hybrid-like nature of
the offspring from the illegitimate union of Dimorphic and Trimorphic Plants'
were published in the 'Journal of the Linnean Soc.' volume 10 page 393. The
abstract here given is nearly the same with that which appeared in the 6th
edition of my 'Origin of Species.')

The infertility which may be observed in various dimorphic 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 ascertained
this by fertilising several flowers, first illegitimately, and twenty-four
hours afterwards legitimately, with pollen taken from a peculiarly coloured
variety, and all the seedlings were similarly coloured; this shows that the
legitimate pollen, though applied twenty-four hours subsequently, had wholly
destroyed or prevented the action of the previously applied illegitimate
pollen. Again, as, in making reciprocal crosses between the same two species,
there is occasionally a great difference in the result, so the same thing
occurs with trimorphic plants; for instance, the mid-styled form of Lythrum
salicaria could be illegitimately fertilised with the greatest ease by pollen
from the longer stamens of the short-styled form, and yielded many seeds; but
the short-styled form did not yield a single seed when fertilised by the
longer stamens of the mid-styled form.

In all these respects the forms of the same undoubted species, when
illegitimately united, behave in exactly the same manner as do two distinct
species when crossed. This led me carefully to observe during four years many
seedlings, raised from several illegitimate unions. The chief result is that
these illegitimate plants, as they may be called, are not fully fertile. It is
possible to raise from dimorphic species, both long-styled and short-styled
illegitimate plants, and from trimorphic plants all three illegitimate forms.
These 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 legitimately fertilised. But such is not the case; they are
all infertile, but in various degrees; some being so utterly and incurably
sterile that they did not yield during four seasons a single seed or even
seed-capsule. These illegitimate plants, which are so sterile, although united
with each other in a legitimate manner, may be strictly compared with hybrids
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 illegitimate 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

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 Lithrum salicaria, and that he determined to try by
crossing 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 completely mistaken.

The facts now given on dimorphic and trimorphic plants are important, because
they show us, first, that the physiological test of lessened fertility, both
in first crosses and in hybrids, is no criterion of specific distinction;
secondly, because we may conclude that there is some unknown bond which
connects the infertility of illegitimate unions with that of their
illegitimate offspring, and we are led to extend the same view to first
crosses and hybrids; thirdly, because we find, and this seems to me of
especial importance, that two or three forms of the same species may exist and
may 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 crosses between distinct species. It is,
however, doubtful 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 distinct species when crossed, and of
their hybrid progeny, depends exclusively on the nature of their sexual
elements, and not on any difference in their structure or general
constitution. We are also led to this same conclusion by considering
reciprocal crosses, in which the male of one species cannot be united, or only
with great difficulty, with the female of a second species, whilst the
converse cross can be effected with perfect facility. That excellent observer,
Gartner, likewise concluded that species when crossed are sterile owing to
differences confined to their reproductive systems.

On the principle which makes it necessary for man, whilst he is selecting and
improving his domestic varieties, to keep them separate, it would clearly be
advantageous to varieties in a state of nature, that is to incipient species,
if they could be kept from blending, either through sexual aversion, or by
becoming mutually sterile. Hence it at one time appeared to me probable, as it
has to others, that this sterility might have been acquired through natural
selection. On this view we must suppose that a shade of lessened fertility
first spontaneously 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, etc., 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 (Muscari 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 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 would 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 reproductive system could not
possibly have been advantageous to either species.

In considering the probability of natural selection having come into action in
rendering species mutually sterile, one of the greatest difficulties will be
found to lie in the existence of many graduated steps from 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; for thus fewer bastardised and deteriorated offspring would be
produced to commingle their blood with the new species in process of
formation. But he who will take the trouble to reflect on the steps by which
this first degree of sterility could be increased through natural selection to
that higher degree which is common to so many species, and which is universal
with species which have been differentiated to a generic or family rank, will
find the subject extraordinarily complex. After mature reflection it seems to
me that this could not have been effected through natural selection. Take the
case of any two species which, when crossed, produce few and sterile
offspring; now, what is there which could favour the survival of those
individuals which happened to be endowed in a slightly higher degree with
mutual infertility, and which thus approached by one small step towards
absolute sterility? 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

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 Kolreuter 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
impossible 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, whatever 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 exposed; and
this difference in susceptibility is clearly incidental on other and unknown
differences in their organisation. So again the capacity in different kinds of
trees to be grafted on each other, or on a third species, differs much, and is
of no advantage to these trees, but is incidental on structural or functional
differences in their woody tissues. We need not feel surprise at sterility
incidentally resulting from crosses between distinct species,--the modified
descendants of a common progenitor,--when we bear in mind how easily the
reproductive system is affected by various causes--often by extremely slight
changes in the conditions of life, by too close interbreeding, and by other
agencies. It is well to bear in mind such cases as that of the Passiflora
alata, which recovered 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 domesticated animals which evince towards each other
sexual incompatibility.

We now at last come to the immediate point under discussion: how is it that,
with some few exceptions in the case of plants, domesticated varieties, such
as those of the dog, fowl, pigeon, several fruit-trees, and culinary
vegetables, which differ from each other in external characters more than many
species, are perfectly fertile when crossed, or even fertile in excess, whilst
closely allied species are almost invariably in some degree sterile? We can,
to a certain extent, give a satisfactory 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 differences 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
subjected 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 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 occasionally be thus induced. Thus, as I believe, we can
understand 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 experimentalists with varieties of the gourd and melon,
and by Kolreuter with one kind of tobacco.

With respect to varieties which have originated in a state of nature, it is
almost hopeless to expect to prove by direct evidence that they have been
rendered mutually sterile; for if even a trace of sterility could be detected,
such varieties would at once be raised by almost every naturalist to the rank
of distinct species. If, for instance, Gartner's statement were fully
confirmed, that the blue and red flowered forms of the pimpernel (Anagallis
arvensis) are sterile when crossed, I presume 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 infertile 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 that the species,
owing to their struggle for existence with numerous competitors, must have
been exposed to more uniform 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 conditions would probably in like manner be
eminently sensitive to the influence of an unnatural cross. Domesticated
productions, 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
injuriously 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 correlation with the colour of the individuals of
the same species. The period of gestation generally differs much in distinct
species, 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 differences, however serviceable they may indirectly be in
keeping the inhabitants of the same country distinct, be thought of such
paramount importance, in comparison with other incidental 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.




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, however,
suffice for the work, and are probably the chief or sole means in the
production of new species. Hence our discussion on the causes and laws of
variability ought in strict order to have preceded the present subject, as
well as inheritance, crossing, etc.; but practically the present arrangement
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 exercised, 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 character 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.

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 prevention 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 judgment 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 predetermined purpose to improve the
breed, he may be said to be selecting unconsciously. (20/1. The term
"unconscious selection" has been objected to as a contradiction; but see some
excellent observations on this head by Prof. Huxley ('Nat. Hist. Review'
October 1864 page 578) who remarks that when the wind heaps up sand-dunes it
sifts and UNCONSCIOUSLY SELECTS from the gravel on the beach grains of sand of
equal size.) Lastly, we have NATURAL SELECTION, 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


What man has effected within recent times in England by methodical selection
is clearly shown by our exhibitions of improved quadrupeds and fancy birds.
With respect to cattle, sheep, and pigs, we owe their great improvement to a
long series of well-known names--Bakewell, Coiling, 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 (20/2. 'On Sheep' 1838 page 60.) the principle of
selection is "that which enables the agriculturist, not only to modify the
character of his flock, but to change it altogether." A great breeder of
Shorthorns (20/3. Mr. J. Wright on Shorthorn Cattle in 'Journal of Royal
Agricult. Soc.' volume 7 pages 208, 209.) 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 (20/4. H.D. Richardson 'On Pigs'
1847 page 44.) 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 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

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 (20/5. 'Journal of Royal Agricult. Soc.' volume 1 page 24.), "It is
therefore very desirable, before any man commences 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 (20/6. 'On Sheep' pages 520, 319.) 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 according to which the London fanciers tried to breed the several sub-
varieties. (20/7. Loudon's 'Mag. of Nat. Hist.' volume 8 1835 page 618.) A
great winner of prizes at the Pigeon-shows (20/8. 'A treatise on the Art of
Breeding the Almond Tumbler' 1851 page 9.), 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; but as I think the goldfinch-beak
the handsomest, I would advise the inexperienced fancier to get the head of a
goldfinch, and keep it by him for his observation." Wonderfully different as
are the 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 (20/9. 'Recreations in Agriculture' volume 2 page
409.) 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 (20/10.
'Youatt on Cattle' pages 191, 227.), 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 (20/11. Ferguson 'Prize Poultry' 1854 page 208.), speaking
of Cochin-China fowls, which are said to differ much in the quality of their
flesh, says, "the best mode is to purchase two young brother-cocks, kill,
dress, and serve up one; if he be indifferent, similarly dispose of the other,
and try again; if, however, he be fine and well-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 (20/12. Wilson in 'Transact. Highland
Agricult. Soc.' quoted in 'Gardener's Chronicle' 1844 page 29.) "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." 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 sheep to an extreme point.
(20/13. Simmonds quoted in 'Gardener's Chronicle' 1855 page 637. And for the
second quotation see 'Youatt on Sheep' page 171.) So "important is the proper
selection of breeding animals considered, that the best flock-masters do not
trust to their own judgment or to that of their shepherds, but employ persons
called 'sheep-classifiers' who make it their special business to attend to
this part of the management of several flocks, and thus to preserve, or if
possible to improve, the best qualities of both parents in the lambs." In
Saxony, "when the lambs are weaned, each in his turn is placed upon a table
that his wool and form may be minutely observed. The finest are selected for
breeding and receive a first mark. When they are one year old, and prior to
shearing them, another close examination of those previously marked takes
place: those in which no defect can be found receive a second mark, and the
rest are condemned. A few months afterwards a third and last scrutiny is made;
the prime rams and ewes receive a third and final mark, but the slightest
blemish is sufficient to cause the rejection of the animal." These sheep are
bred and valued almost exclusively 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 (20/14. Robinet 'Vers a Soie' 1848 page 271.) 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. (20/15. Quatrefages 'Les Maladies du Ver
a Soie' 1859 page 101.) In China, near Shanghai, the inhabitants 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. (20/16. M. Simon in 'Bull. de la Soc.
d'Acclimat.' tome 9 1862 page 221.)

The care which successful breeders take in matching their birds is surprising.
Sir John Sebright, whose fame is perpetuated 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." (20/17. 'The Poultry
Chronicle' volume 1 1854 page 607.) Mr. Bult, whose pouter-pigeons won so many
prizes, and were exported to North America under the charge of a man sent on
purpose, told me that he always deliberated for several days before he matched
each pair. Hence we can understand the advice of an eminent fancier, who
writes (20/18. J.M. Eaton 'A Treatise on Fancy Pigeons' 1852 page 14 and 'A
Treatise on the Almond Tumbler' 1851 page 11.) "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 (20/19. 'Journal Royal Agricultural Soc.'
volume 6 page 22.) 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 furnished would be at once disqualified; beards were ordered,
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 occasionally 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." (20/20. 'Poultry Chronicle' volume 2 1855 page 596.)

Mr. Tollet, 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 proportion
of four to three. Here is a curious case (20/21. Isid. Geoffroy St.-Hilaire
'Hist. Nat. Gen.' tome 3 page 254.) 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, etc., it is
almost indispensable 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 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 (20/22. 'Gardener's Chronicle' 1850
page 198.) how "many a patient hour was devoted," whilst he was young, to the
detection of differences in peas intended for seed. Mr. Barnet (20/23.
'Transact. Hort. Soc.' volume 6 page 152.) remarks that the old scarlet
American strawberry was cultivated for more than a century without producing a
single variety; and another writer observes 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 variations 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 methodical selection with
plants; but in fact the great improvement of all our anciently cultivated
plants may be attributed to selection long carried on, in part methodically,
and in part unconsciously. I have shown in a former chapter how the weight of
the gooseberry has been increased by systematic selection and culture. The
flowers of the Heartsease have been similarly increased in size and regularity
of outline. With the Cineraria, Mr. Glenny (20/24. 'Journal of Horticulture'
1862 page 369.) "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 (20/25 'Transact. Hort. Soc.' volume 4 page 381.), after
sowing during several years 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. (20/26. 'Transact. Hort. Soc.' volume 4 page 285.) The Canterbury bell
(Campanula medium) was doubled by careful selection in four generations.
(20/27. Rev. W. Bromehead in 'Gardener's Chronicle' 1857 page 550.) In four
years Mr. Buckman (20/28. 'Gardener's Chronicle' 1862 page 721.), 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. (20/29.
Dr. Anderson in 'The Bee' volume 6 page 96; Mr. Barnes in 'Gardener's
Chronicle' 1844 page 476.) A more curious case is offered by the beet plant,
which since its cultivation 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. (20/30. Godron 'De l'Espece' 1859 tome 2 page 69;
'Gardener's Chronicle' 1854 page 258.)


In attributing so much importance to the selection of animals and plants, it
may be objected, that methodical selection 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 corresponding result has been gained; but it would be a
greater error to suppose, as we shall immediately see, that its importance 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 occasionally 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 (20/31. 'On Sheep' page 18.), who
has discussed all the passages in relation to breeding in the Old Testament,
concludes that at this early period "some of the best principles of breeding
must have been steadily and long pursued." It was ordered, according to Moses,
that "Thou shalt not let thy cattle gender with a diverse kind;" but mules
were purchased (20/32. Volz 'Beitrage zur Kulturgeschichte' 1852 s. 47.) so
that at this early period other nations must have crossed the horse and ass.
It is said (20/33. Mitford 'History of Greece' volume 1 page 73.) 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 5) speaks of
Aeneas' horses as bred from mares which were put to the steeds of Laomedon.
Plato, in his 'Republic' says to Glaucus, "I see that you raise at your house
a great many dogs for the chase. Do you take care about breeding and pairing
them? Among animals of good blood, are there not always some which are
superior to the rest?" To which Glaucus answers in the affirmative. (20/34.
Dr. Dally translated in 'Anthropological Review' May 1864 page 101.) Alexander
the Great selected the finest Indian cattle to send to Macedonia to improve
the breed. (20/35. Volz 'Beitrage' etc. 1852 s. 80.) According to Pliny (20/36
'History of the World' chapter 45.), King Pyrrhus had an especially valuable
breed of oxen: and he did not suffer the bulls and cows to come together till
four years old, that the breed might not degenerate. Virgil, in his Georgics
(lib. 3), 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 to examine if their tongues are swarthy.
We have seen that the 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." (20/37. 'Gardener's
Chronicle' 1848 page 323.) According to Tacitus, the Celts attended to the
races of their domestic animals; and Caesar states that they paid high prices
to merchants for fine imported horses. (20/38. Reynier 'De l'Economie des
Celtes' 1818 pages 487, 503.) In regard to plants, Virgil speaks of yearly
culling the largest seeds; and Celsus says, "where the corn and crop is but
small, we must pick out the best ears of corn, and of them lay up our seed
separately by itself." (20/39. Le Couteur on 'Wheat' page 15.)

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. (20/40. Michel 'Des Haras' 1861 page 84.)
Even in a country so little civilised as Ireland during the ninth century, it
would appear from some ancient verses (20/41. Sir W. Wilde an 'Essay on
Unmanufactured Animal Remains' etc. 1860 page 11.), 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.
I brought with me a stallion and a mare
From the beautiful stud of Manannan,
A bull and a white cow from Druim Cain.

Athelstan, in 930, received running-horses as a present from Germany; and he
prohibited the exportation of English horses. King John imported "one hundred
chosen stallions from Flanders." (20/42. Col. Hamilton Smith 'Nat. Library'
volume 12 Horses, pages 135, 140.) On June 16th, 1305, the Prince of Wales
wrote to the Archbishop of Canterbury, begging for the loan of any choice
stallion, and promising its return at the end of the season. (20/43. Michel
'Des Haras' page 90.) 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. (20/44. Mr. Baker
'History of the Horse' 'Veterinary' volume 13 page 423.) Some of our earlier
kings passed laws against the slaughtering 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. (20/45. M. l'Abbe Carlier in 'Journal de Physique' volume 24 1784
page 181; this memoir contains much information on the ancient selection of
sheep; and is my authority for rams not being killed young in England.)

The Emperor Akbar Khan before the year l600 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. Markham in 1631 tells the breeder "to elect the
largest and goodliest 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 (20/46. 'Gardener's Chronicle' 1843 page 389.) 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,
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." (20/47. 'Communications to Board of Agriculture'
quoted in Dr. Darwin 'Phytologia' 1800 page 451.)

In the great work on China published in the last century by the Jesuits, and
which is chiefly compiled from ancient Chinese encyclopaedias, it is said that
with sheep "improving the breed consists in choosing with particular care the
lambs which are destined for propagation, in nourishing them well, and in
keeping the flocks separate." The same principles were applied by the Chinese
to various plants and fruit-trees. (20/48. 'Memoire sur les Chinois' 1786 tome
11 page 55; tome 5 page 507.) 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 Emperor 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. (20/49. 'Recherches sur l'Agriculture des Chinois' par L.
D'Hervey Saint-Denys 1850 page 229. With respect to Khang-hi see Huc's
'Chinese Empire' page 311.) Even with flowers, the tree paeony (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. (20/50. Anderson in 'Linn. Transact.' volume 12 page 253.)

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. Roulin
(20/51. 'Mem. de l'Acad.' (divers savants), tome 6 1835 page 333.), however,
describes in Columbia a naked race of cattle, which are not allowed to
increase, on account of their delicate constitution. According to Azara
(20/52. 'Des Quadrupedes du Paraguay' 1801 tome 2 pages 333, 371.) horses are
often born in Paraguay with curly hair; but, as the natives 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
extraordinary 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
dromedary can boast a genealogy far longer than the descendants of the Darley
Arabian." (20/53. 'The Great Sahara' by the Rev. H.B. Tristram 1860 page 238.)
According to Pallas the Mongolians 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. (20/54. Pallas 'Act.
Acad. St. Petersburg' 1777 page 249. Moorcroft and Trebeck 'Travels in the
Himalayan Provinces' 1841.)

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 Varro, the wild ass was
formerly caught and crossed with the tame animal to improve the breed, in the
same manner as at the present day the natives of Java sometimes drive their
cattle into the forests to cross with the wild Banteng (Bos sondaicus).
(20/55. Quoted from Raffles in the 'Indian Field' 1859 page 196: for Varro see
Pallas ut supra.) 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 remarkably uniform manner (20/56. Erman 'Travels in Siberia'
English translation volume 1 page 453.); 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 superiority. I have heard of certain tribes
of Esquimaux who take pride in their teams of dogs being uniformly coloured.
In Guiana, as Sir H. Schomburgk informs me (20/57. See also 'Journal of R.
Geograph. Soc.' volume 13 part 1 page 65.), 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 Robert 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. (20/58. Livingstone 'First Travels' pages 191,
439, 565; see also 'Expedition to the Zambesi' 1865 page 495, for an analogous
case respecting a good breed of goats.) At Falaba Mr. Winwood Reade 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 Damaras take great delight in having whole droves of
cattle of the same colour, and they prize their oxen in proportion to the size
of their horns. "The Namaquas have a perfect mania for a uniform team; and
almost all the people of Southern Africa value their cattle next to their
women, and take a pride in possessing animals that look high-bred. They rarely
or never make use of a handsome animal as a beast of burden." (20/59.
Andersson 'Travels in South Africa' pages 232, 318, 319.) The power of
discrimination which these savages possess is wonderful, and they can
recognise to which tribe any cattle belong. Mr. Andersson further informs 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 subjugated by the Spaniards. (20/60. Dr. Vavasseur in 'Bull. de La Soc.
d'Acclimat.' tome 8 1861 page 136.) The Incas annually held great hunts, when
all the wild animals were driven from an immense circuit to a central point.
The beasts of prey were first destroyed as injurious. The wild Guanacos and
Vicunas were sheared; the old males and females killed, and the others set at
liberty. The various kinds of deer were examined; the old males and females
were likewise killed, "but the young females, with a certain number of males,
selected from the most beautiful and strong," 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. (20/61. 'The Natural History of Dee
Side' 1855 page 476.) In regard to the domesticated llamas and alpacas, they
were separated in the time of the Incas according to colour: and if by chance
one in a flock was born of the wrong colour, it was eventually put into
another flock.

In the genus Auchenia there are four forms,--the Guanaco and Vicuna, found
wild and undoubtedly distinct species; the Llama and Alpaca, known only in a
domesticated condition. 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 exportation to
Australia, and who has made many experiments on their propagation, adduces
arguments (20/62. 'Bull. de la Soc. d'Acclimat.' tome 7 1860 page 457.) 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 preserved. With
respect to cattle, "an early record," according to Youatt (20/63. 'Cattle'
page 48.) "speaks of a hundred white cows with red ears being demanded as a
compensation by the princes of North 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 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 competition sprung up for her
possession, and she realised a considerable price." (20/64. Livingstone
'Travels' page 576; Andersson 'Lake Ngami' 1856 page 222. With respect to the
sale in Kaffraria see 'Quarterly Review' 1860 page 139.) 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.
(20/65. 'Memoire sur les Chinois' by the Jesuits 1786 tome 11 page 57.) 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 liart
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" (20/66. F. Michel
'Des Haras' pages 47, 50.); 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." (20/67. Col. Hamilton Smith 'Dogs' in 'Nat. Lib.'
volume 10 page 103.)

Turning to poultry, the old Roman 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. (20/68. Azara 'Quadrupedes du Paraguay' tome 2 page 324.) In Guiana,
as I am informed by Sir R. Schomburgk, 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 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." (20/69. Sidney's edition of Youatt 1860 pages 24, 25.) 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."
(20/70. 'Rural Economy of Yorkshire' volume 2 page 182.) In a part of Germany
the cattle of the Race de Gfoehl are valued for many good qualities, but they
must have horns of a particular curvature and tint, so much so that mechanical
means are applied if they take a wrong direction; but the inhabitants
"consider it of the highest importance that the nostrils of the bull should be
flesh-coloured, and the eyelashes light; this is an indispensable condition. A
calf with blue nostrils would not be purchased, or purchased at a very low
price." (20/71. Moll et Gayot 'Du Boeuf' 1860 page 547.) Therefore let no man
say that any point or character is too trifling to be methodically attended to
and selected by breeders.


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 VIII.'s reign of all under-
sized mares, are instances of a process the reverse of selection in the
ordinary sense of the 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 fantail, and was far from knowing 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, fleeter fox-hounds were desired and produced, but probably
without any one distinctly foreseeing what they would become. Our pointers and
setters, the latter almost certainly descended from large spaniels, have been
greatly modified in accordance with fashion and the desire for increased
speed. Wolves have become extinct, and so has the wolf-dog; deer have become
rarer, bulls are no longer baited, and the corresponding breeds of the dog
have answered to the change. But we may feel almost sure that when, for
instance, bulls 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
circumstances changed, men unconsciously and slowly modified their course of

With racehorses selection for swiftness has been followed methodically, and
our horses now easily surpass their progenitors. The increased size and
different appearance of the English racehorse led a good observer in India to
ask," Could any one in this year of 1856, looking at our racehorses, conceive
that they were the result of the union of the Arab horse and the African
mare?" (20/72. 'The India Sporting Review' volume 2 page 181; 'The Stud Farm'
by Cecil page 58.) 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 (20/73. 'The Horse' page 22.), 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 disappearing." 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 (20/74. 'History of England' volume 1 page 316.)
remarks, "Two men whose authority on such subjects was held in great esteem,
the Duke of Newcastle and Sir John Fenwick, pronounced that the meanest hack
ever imported from Tangier would produce a finer progeny 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 appearance from any natural
species, and which from its size has so astonished many Eastern princes, was
probably formed by the heaviest and most powerful animals having been selected
during many generations in Flanders and England, but without the least
intention or expectation of creating a horse such as we now see. If we go back
to an early period of history, we behold in the antique Greek statues, as
Schaaffhausen has remarked (20/75. 'Ueber Bestandigkeit der Arten.'), 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. Bakewell for upwards of fifty years. There
is not a suspicion existing in the mind of any one at all acquainted with the
subject that the owner of either flock has deviated in any one instance from
the pure blood of Mr. Bakewell's flock; yet the difference between the sheep
possessed by these two gentlemen is so great, that they have the appearance of
being quite different varieties." (20/76. 'Youatt on Sheep' page 315.) 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. Nathusius--and a more competent witness could not be
cited--observes that, though the Shorthorns are remarkably uniform in
appearance (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. (20/77. 'Ueber Shorthorn Rindvieh' 1857 s. 51.) The
Hereford cattle assumed their present well-marked character soon after the
year 1769, through careful selection by Mr. Tomkins (20/78. Low 'Domesticated
Animals' 1845 page 363.) and the breed has lately split into two strains--one
strain having a white face, and differing slightly, it is said (20/79.
'Quarterly Review' 1849 page 392.), 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. (20/80. H. von Nathusius 'Vorstudien...Schweineschadel' 1864 s
140.) Keeping in mind how rapidly all animals increase, and that some must be
annually slaughtered and some saved for breeding, then, if the same breeder
during a long course of years deliberately settles which shall be saved and
which shall be killed, it is almost inevitable that his individual turn of
mind will influence the character of his stock, without his having had any
intention to modify the breed.

Unconscious selection in the strictest sense of the word, that is, the saving
of the more useful animals and the neglect or slaughter of the less useful,
without any thought of the future, must have gone on occasionally from the
remotest period and amongst the most barbarous nations. Savages often suffer
from famines, and are sometimes expelled by war from their own homes. In such
cases it can hardly be doubted that they would save their most useful animals.
When the Fuegians are hard pressed by want, they kill their old women for food
rather than their dogs; for, as we were assured, "old women no use--dogs catch
otters." The same sound sense would surely lead them to preserve their more
useful dogs when still harder pressed by famine. Mr. Oldfield, who has seen so
much of the aborigines of Australia, informs me 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 there will have been some selection from an
extremely remote period, but without any prefixed standard of excellence or
thought of the future. We 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. (20/81. See also Dr. Christ in Rutimeyer's
'Pfahlbauten' 1861 s. 226.) The pears described by Pliny were evidently
extremely inferior in quality to our present pears. We can realise the effects
of long-continued selection and cultivation in another way, for would any one
in his senses expect to raise a first-rate apple from the seed of a truly wild
crab, or a luscious melting pear from the wild pear? Alphonse de Candolle
informs me that he has lately seen on an ancient mosaic at Rome a
representation of the melon; and as the Rotnans, 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 (20/82. The passage is given 'Bull. Soc.
d'Acclimat.' 1858 page 11.) on comparing the flowers, 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
(20/83. 'Journal of Horticulture' 1862 page 394.), in speaking of the
varieties of Pelargonium raised by Mr. Garth only twenty-two years before,
remarks, "What a rage they excited: surely we had attained perfection, it was
said; and now not one of the flowers of those days will be looked at. But none
the less is the debt of gratitude which we owe to those who saw what was to be
done, and did it." Mr. Paul, the well-known horticulturist, in writing of the
same flower (20/84. 'Gardener's Chronicle' 1857 page 85.), 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 horticulturist appreciates and illustrates
the gradual and accumulative force of selection! The Dahlia has advanced in
beauty in a like manner; the line of improvement being guided by fashion, and
by the successive modifications which the flower slowly underwent. (20/85. See
Mr. Wildman's address to the Floricult. Soc. in 'Gardener's Chronicle' 1843
page 86.) A steady and gradual change has been noticed in many other flowers:
thus an old florist (20/86. 'Journal of Horticulture' October 24, 1865 page
239.), 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 earliest
known flower-garden in Europe, namely at Padua, dates only from the year 1545.
(20/87. Prescott 'Hist. of Mexico' volume 2 page 61.)


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 distinct 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 cultivated 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, etc., 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. (20/88. Sagaret
'Pomologie Physiologique' 1830 page 47; Gallesio 'Teoria della Riproduzione'
1816 page 88; Godron 'De l'Espece' 1859 tome 2 pages 63, 67, 70. In my tenth
and eleventh chapters I have given details on the potato; and I can confirm
similar remarks with respect to the onion. I have also shown how far Naudin
concurs in regard to the varieties of the melon.)

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
necessarily 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 resemble 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 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, etc., 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
corresponds 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 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 simultaneously 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 somewhat
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 generally 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 cultivated 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
continually augmented; whilst other variations, excepting such as inevitably
appeared through correlation, were neglected and lost. We may therefore infer
that most plants might be made, through long-continued selection, to yield
races as different from one another in any character as they now are in those
parts for which they are valued and cultivated.

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 racehorse and dray-horse. But fleetness and strength are
valued in camels and dogs; and we have with the former the swift dromedary and
heavy camel; with the latter the greyhound and mastiff. But dogs are valued
even in a higher degree for their mental qualities and senses; and every one
knows how greatly the races differ in these respects. On the other hand, where
the dog is kept solely to serve for food, as in the Polynesian islands and
China, it is described as an extremely stupid animal. (20/89. Godron 'De
l'Espece' tome 2 page 27.) 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." (20/90. 'The
Anthropological Treatises of Blumenbach' 1856 page 292.) Had Blumenbach
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 excellently 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 character 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.

I will conclude this chapter by some remarks on an important subject. With
animals such as the giraffe, of which the whole structure is admirably co-
ordinated for certain purposes, it has been supposed that all the parts must
have been simultaneously modified; and it has been argued that, on the
principle of natural selection, this is scarcely possible. But in thus
arguing, it has been tacitly assumed that the variations must have been abrupt
and great. No doubt, if the neck of a ruminant were suddenly to become greatly
elongated, the fore limbs and back would have to be simultaneously
strengthened and modified; but it cannot be denied that an animal might have
its neck, or head, or tongue, or fore-limbs elongated a very little without
any corresponding modification 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
survivors, there would be some progress, slow and fluctuating though it would
be, towards the admirably coordinated 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 limbs, all adapted for extreme
fleetness, and for running down weak prey. Now, from what we see of the
variability of animals, and from 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 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 (20/91. Mr. J.J. Murphy in his opening address to
the Belfast Nat. Hist. Soc. as given in the 'Belfast Northern Whig' November
19, 1866. Mr. Murphy here follows the line of argument against my views
previously and more cautiously given by the Rev. C. Pritchard, Pres. Royal
Astronomical Soc., in his sermon Appendix page 33 preached before the British
Association at Nottingham 1866.) 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 improbability 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 subsequently 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 has often been advanced as an excellent instance of adaptation. Short-
sight, which is often inherited, permits a person to see distinctly a minute
object at so near a distance that it would be indistinct to ordinary eyes; and
here we have a capacity which might be serviceable under certain conditions,
abruptly gained. The Fuegians on board the Beagle could certainly see distant
objects more distinctly than our sailors with all their long 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 (20/92. On the Vision of Fishes and Amphibia,
translated in 'Annals and Mag. of Nat. Hist.' volume 18 1866 page 469.), 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 advantageous to the animal whilst under
water, without serious detriment to its power of vision in the air. It is of
course impossible to conjecture by what steps the fundamental structure of the
eye in the Vertebrata was originally acquired, for we know nothing about this
organ in the first progenitors of the class. With respect to the lowest
animals in the scale, the transitional states through which the eye at first
probably passed, can by the aid of analogy be indicated, as I have attempted
to show in my 'Origin of Species.' (20/93. Sixth edition 1872 page 144.)


SELECTION, continued.



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 differing in
constitution and in various characters would succeed best, and so be naturally
selected. Hence perhaps it is that the few domesticated animals kept by
savages partake, as has been remarked by more than one writer, of the wild
appearance of their masters, and likewise resemble natural species. Even in
long-civilised countries, at least in the wilder parts, natural selection must
act on our domestic races. It is obvious that varieties having very different
habits, constitution, and structure, would succeed best on mountains and on
rich lowland pastures. For example, the improved Leicester sheep were formerly
taken to the Lammermuir Hills; but an intelligent sheep-master reported that
"our coarse lean pastures were unequal to the task of supporting such heavy-
bodied sheep; and they gradually dwindled away into less and less bulk: each
generation was inferior to the preceding one; and when the spring was severe,
seldom more than two-thirds of the lambs survived the ravages of the storms."
(21/1. Quoted by Youatt on 'Sheep' page 325. See also Youatt on 'Cattle' pages
62, 69.) So with the mountain cattle of North Wales and the Hebrides, it has
been found that they could not withstand being crossed with the larger and
more delicate lowland breeds. Two French naturalists, in describing the horses
of Circassia, remark that, subjected as they are to extreme vicissitudes of
climate, having to search for scanty pasture, and exposed to constant danger
from wolves, the strongest and most vigorous alone survive. (21/2. MM.
Lherbette and De Quatrefages in 'Bull. Soc. d'Acclimat.' tome 8 1861 page

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 massive 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. Now the English game-cock has not only been improved
during many years by man's careful selection, but in addition, as Mr.
Tegetmeier has remarked (21/3. 'The Poultry Book' 1866 page 123. Mr.
Tegetmeier, 'The Homing or Carrier Pigeon' 1871 pages 45-58.), by a kind of
natural selection, for the strongest, most active and courageous birds have
stricken down their antagonists in the cockpit, generation after generation,
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." (21/4. 'Youatt on Sheep' page 312.) 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 selection
which we have seen is occasionally and unconsciously 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
productions 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.

When man attempts to make a breed with some serious defect in structure, or in
the mutual relation of the several parts, he will partly or completely fail,
or encounter much difficulty; he is in fact resisted by a form of natural
selection. We have seen that an attempt was once made in Yorkshire to breed
cattle with enormous buttocks, but the cows perished so often in bringing
forth their calves, that the attempt had to be given up. In rearing short-
faced tumblers, Mr. Eaton says (21/5. 'Treatise on the Almond Tumbler' 1851
page 33.), "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 Niata 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, etc.; this the 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
Roulin, 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 topknots,--hornless bulls and rams, which consequently
cannot cope with other males, and thus have a poor chance of leaving
offspring,--seedless plants, and many other such cases.

Colour is generally esteemed by the systematic naturalist as unimportant: let
us, therefore, see how far it indirectly affects our domestic productions, and
how far it would affect them if they were left exposed to the full force of
natural selection. In a future chapter I shall have to show that
constitutional peculiarities of the strangest kind, entailing liability to the
action of certain poisons, are correlated with the colour of the skin. I will
here give a single case, on the high authority of Professor Wyman; he informs
me that, being surprised at all the pigs in a part of Virginia being black, he
made inquiries, and ascertained that these animals feed on the roots of the
Lachnanthes tinctoria, which colours their bones pink, and, excepting in the
case of the black varieties, causes the hoofs to drop off. Hence, as one of
the squatters remarked, "we select the black members of the litter for
raising, as they alone have a good chance of living." So that here we have
artificial and natural selection working hand in hand. I may add that in the
Tarentino the inhabitants keep black sheep alone, because the Hypericum
crispum abounds there; and this plant does not injure black sheep, but kills
the white ones in about a fortnight's time. (21/6. Dr. Heusinger
'Wochenschrift fur die Hei1kunde' Berlin 1846 s. 279.)

Complexion, and liability to certain diseases, are believed to run together in
man and the lower animals. Thus white terriers suffer more than those of any
other colour from the fatal distemper. (21/7. Youatt on the 'Dog' page 232.)
In North America plum-trees are liable to a disease which Downing (21/8. 'The
Fruit-trees of America' 1845 page 270: for peaches page 466.) 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 Mauritius, 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. (21/9. 'Proc. Royal Soc. of Arts and
Sciences of Mauritius' 1852 page 135.) 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. (21/10.
'Gardener's Chronicle' 1856 page 379.) 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. (21/11. Quatrefages
'Maladies Actuelles du Ver a Soie' 1859 pages 12, 214.) 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. (21/12. 'Gardener's Chronicle' 1851 page 595.) White verbenas are
especially liable to mildew. (21/13. 'Journal of Horticulture' 1862 page 476.)
Near Malaga, during an early period of the vine-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
comparatively 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. (21/14. 'Gardener's Chronicle'
1852 pages 435, 691.) 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 (21/15.
Bechstein 'Naturgesch. Deutschlands' 1801 b. 1 s. 310.) 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 (21/16. Prichard 'Phys. Hist. of Mankind' 1851 volume 1
page 224.), was peculiarly sensitive to the bites of insects. In the West

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