NATURAL SELECTION AS AFFECTING DOMESTIC PRODUCTIONS—CHARACTERS WHICH
APPEAR OF TRIFLING VALUE OFTEN OF REAL IMPORTANCE—CIRCUMSTANCES
FAVOURABLE TO SELECTION BY MAN—FACILITY IN PREVENTING CROSSES, AND THE
NATURE OF THE CONDITIONS—CLOSE ATTENTION AND PERSEVERANCE
INDISPENSABLE—THE PRODUCTION OF A LARGE NUMBER OF INDIVIDUALS
ESPECIALLY FAVOURABLE—WHEN NO SELECTION IS APPLIED, DISTINCT RACES ARE
NOT FORMED—HIGHLY-BRED ANIMALS LIABLE TO DEGENERATION—TENDENCY IN MAN
TO CARRY THE SELECTION OF EACH CHARACTER TO AN EXTREME POINT, LEADING
TO DIVERGENCE OF CHARACTER, RARELY TO CONVERGENCE—CHARACTERS CONTINUING
TO VARY IN THE SAME DIRECTION IN WHICH THEY HAVE ALREADY
VARIED—DIVERGENCE OF CHARACTER, WITH THE EXTINCTION OF INTERMEDIATE
VARIETIES, LEADS TO DISTINCTNESS IN OUR DOMESTIC RACES—LIMIT TO THE
POWER OF SELECTION—LAPSE OF TIME IMPORTANT—MANNER IN WHICH DOMESTIC
RACES HAVE ORIGINATED—SUMMARY.
_Natural Selection, or the Survival of the Fittest, as affecting
domestic productions._—We know little on this head. But as animals kept
by savages have to provide throughout the year their own food either
entirely or to a large extent, it can hardly be doubted that in
different countries, varieties 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.”[1] So with the mountain cattle of North Wales and the
Hebrides, it has been found that they could not withstand being crossed
with the larger and more delicate lowland breeds. Two French
naturalists, in describing the horses of 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.[2]
Every one must have been struck with the surpassing grace, strength,
and vigour of the Game-cock, with its bold and confident air, its long,
yet firm neck, compact body, powerful and closely pressed wings,
muscular thighs, strong beak 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,[3] by a
kind of natural selection, for the strongest, most active and
courageous birds have stricken down their antagonists in the cockpit,
generation after 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.”[4] But in this case we are quite unable
to disentangle the effects of the direct action of the conditions of
life,—of use or habit—of natural selection—and of that kind of
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,[5] “I am convinced that better head and beak birds have perished
in the shell than ever were hatched; the reason being that the
amazingly short-faced bird cannot reach and break the shell with its
beak, and so perishes.” Here is a more curious case, in which natural
selection comes into play only at long intervals of time: during
ordinary seasons the 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.[6]
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.[7] In North
America plum-trees are liable to a disease which Downing[8] believes is
not caused by insects; the kinds bearing purple fruit are most
affected, “and we have never known the green or yellow fruited
varieties infected until the other sorts had first become filled with
the knots.” On the other hand, peaches in North America suffer much
from a disease called the _yellows,_ which seems to be peculiar to that
continent, and more than nine-tenths of the victims, “when the disease
first appeared, were the yellow-fleshed peaches. The white-fleshed
kinds are much more rarely attacked; in some parts of the country
never.” In 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.[9] Now, if these
plants had been forced to struggle with other competing plants and
enemies, there cannot be a doubt that the colour of the flesh or skin
of the fruit, unimportant as these characters are considered, would
have rigorously determined their existence.
Liability to the attacks of parasites is also connected with colour.
White chickens are certainly more subject than dark-coloured chickens
to the “gapes,” which is caused by a parasitic worm in the trachea.[10]
On the other hand, experience has shown that in France the caterpillars
which produce white cocoons resist the deadly fungus better than those
producing yellow cocoons.[11] Analogous facts have been observed with
plants: a new and beautiful white onion, imported from France, though
planted close to other kinds, was alone attacked by a parasitic
fungus.[12] White verbenas are especially liable to mildew.[13] 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.[14] In a former chapter it was shown how curiously liable one
variety of the strawberry is to mildew.
It is certain that insects regulate in many cases the range and even
the existence of the higher animals, whilst living under their natural
conditions. Under domestication light-coloured animals suffer most: in
Thuringia[15] the inhabitants do not like grey, white, or pale cattle,
because they are much more troubled by various kinds of flies than the
brown, red, or black cattle. An Albino negro, it has been remarked,[16]
was peculiarly sensitive to the bites of insects. In the West
Indies[17] it is said that “the only horned cattle fit for work are
those which have a good deal of black in them. The white are terribly
tormented by the insects; and they are weak and sluggish in proportion
to the white.”
In Devonshire there is a prejudice against white pigs, because it is
believed that the sun blisters them when turned out;[18] and I knew a
man who would not keep white pigs in Kent, for the same reason. The
scorching of flowers by the sun seems likewise to depend much on
colour; thus, dark pelargoniums suffer most; and from various accounts
it is clear that the cloth-of-gold variety will not withstand a degree
of exposure to sunshine which other varieties enjoy. Another amateur
asserts that not only all dark-coloured verbenas, but likewise
scarlets, suffer from the sun: “the paler kinds stand better, and pale
blue is perhaps the best of all.” So again with the heartsease (_Viola
tricolor_); hot weather suits the blotched sorts, whilst it destroys
the beautiful markings of some other kinds.[19] During one extremely
cold season in Holland all red-flowered hyacinths were observed to be
very inferior in quality. It is believed by many agriculturists that
red wheat is hardier in northern climates than white wheat.[20]
With animals, white varieties from being conspicuous are the most
liable to be attacked by beasts and birds of prey. In parts of France
and Germany where hawks abound, persons are advised not to keep white
pigeons; for, as Parmentier says, “it is certain that in a flock the
white always first fall victims to the kite.” In Belgium, where so many
societies have been established for the flight of carrier-pigeons,
white is the one colour which for the same reason is disliked.[21]
Prof. G. Jaeger[22] whilst fishing found four pigeons which had been
killed by hawks, and all were white; on another occasion he examined
the eyrie of a hawk, and the feathers of the pigeons which had been
caught were all of a white or yellow colour. On the other hand, it is
said that the sea-eagle (_Falco ossifragus,_ Linn.) on the west coast
of Ireland picks out the black fowls, so that “the villagers avoid as
much as possible rearing birds of that colour.” M. Daudin,[23] speaking
of white rabbits kept in warrens in Russia, remarks that their colour
is a great disadvantage, as they are thus more exposed to attack, and
can be seen during bright nights from a distance. A gentleman in Kent,
who failed to stock his woods with a nearly white and hardy kind of
rabbit, accounted in the same manner for their early disappearance. Any
one who will watch a white cat prowling after her prey will soon
perceive under what a disadvantage she lies.
The white Tartarian cherry, “owing either to its colour being so much
like that of the leaves, or to the fruit always appearing from a
distance unripe,” is not so readily attacked by birds as other sorts.
The yellow-fruited raspberry, which generally comes nearly true by
seed, “is very little molested by birds, who evidently are not fond of
it; so that nets may be dispensed with in places where nothing else
will protect the red fruit.”[24] This immunity, though a benefit to the
gardener, would be a disadvantage in a state of nature both to the
cherry and raspberry, as dissemination depends on birds. I noticed
during several winters that some trees of the yellow-berried holly,
which were raised from seed from a tree found wild by my father
remained covered with fruit, whilst not a scarlet berry could be seen
on the adjoining trees of the common kind. A friend informs me that a
mountain-ash (_Pyrus aucuparia_) growing in his garden bears berries
which, though not differently coloured, are always devoured by birds
before those on the other trees. This variety of the mountain-ash would
thus be more freely disseminated, and the yellow-berried variety of the
holly less freely, than the common varieties of these two trees.
Independently of colour, trifling differences are sometimes found to be
of importance to plants under cultivation, and would be of paramount
importance if they had to fight their own battle and to struggle with
many competitors. The thin-shelled peas, called _pois sans parchemin,_
are attacked by birds[25] much more commonly than ordinary peas. On the
other hand, the purple-podded pea, which has a hard shell, escaped the
attacks of tomtits (_Parus major_) in my garden far better than any
other kind. The thin-shelled walnut likewise suffers greatly from the
tomtit.[26] These same birds have been observed to pass over and thus
favour the filbert, destroying only the other kinds of nuts which grew
in the same orchard.[27]
Certain varieties of the pear have soft bark, and these suffer severely
from wood-boring beetles; whilst other varieties are known to resist
their attacks much better.[28] In North America the smoothness, or
absence of down on the fruit, makes a great difference in the attacks
of the weevil, “which is the uncompromising foe of all smooth
stone-fruits;” and the cultivator “has the frequent mortification of
seeing nearly all, or indeed often the whole crop, fall from the trees
when half or two-thirds grown.” Hence the nectarine suffers more than
the peach. A particular variety of the Morello cherry, raised in North
America, is, without any assignable cause, more liable to be injured by
this same insect than other cherry-trees.[29] From some unknown cause,
certain varieties of the apple enjoy, as we have seen, the great
advantage in various parts of the world of not being infested by the
coccus. On the other hand, a particular case has been recorded in which
aphides confined themselves to the Winter Nelis pear and touched no
other kind in an extensive orchard.[30] The existence of minute glands
on the leaves of peaches, nectarines, and apricots, would not be
esteemed by botanists as a character of the least importance for they
are present or absent in closely-related sub-varieties, descended from
the same parent-tree; yet there is good evidence[31] that the absence
of glands leads to mildew, which is highly injurious to these trees.
A difference either in flavour or in the amount of nutriment in certain
varieties causes them to be more eagerly attacked by various enemies
than other varieties of the same species. Bullfinches (_Pyrrhula
vulgaris_) injure our fruit-trees by devouring the flower-buds, and a
pair of these birds have been seen “to denude a large plum-tree in a
couple of days of almost every bud;” but certain varieties[32] of the
apple and thorn (_Cratægus oxyacantha_) are more especially liable to
be attacked. A striking instance of this was observed in Mr. Rivers’s
garden, in which two rows of a particular variety of plum[33] had to be
carefully protected, as they were usually stripped of all their buds
during the winter, whilst other sorts growing near them escaped. The
root (or enlarged stem) of Laing’s Swedish turnip is preferred by
hares, and therefore suffers more than other varieties. Hares and
rabbits eat down common rye before St. John’s-day-rye, when both grow
together.[34] In the south of France, when an orchard of almond-trees
is formed, the nuts of the bitter variety are sown, “in order that they
may not be devoured by field-mice”;[35] so we see the use of the bitter
principle in almonds.
Other slight differences, which would be thought quite unimportant, are
no doubt sometimes of great service both to plants and animals. The
Whitesmith’s gooseberry, as formerly stated, produces its leaves later
than other varieties, and, as the flowers are thus left unprotected,
the fruit often fails. In one variety of the cherry, according to Mr.
Rivers,[36] the petals are much curled backwards, and in consequence of
this the stigmas were observed to be killed by a severe frost; whilst
at the same time, in another variety with incurved petals, the stigmas
were not in the least injured. The straw of the Fenton wheat is
remarkably unequal in height; and a competent observer believes that
this variety is highly productive, partly because the ears from being
distributed at various heights above the ground are less crowded
together. The same observer maintains that in the upright varieties the
divergent awns are serviceable by breaking the shocks when the ears are
dashed together by the wind.[37] If several varieties of a plant are
grown together, and the seed is indiscriminately harvested, it is clear
that the hardier and more productive kinds will, by a sort of natural
selection, gradually prevail over the others; this takes place, as
Colonel Le Couteur believes,[38] in our wheat-fields, for, as formerly
shown, no variety is quite uniform in character. The same thing, as I
am assured by nurserymen, would take place in our flower-gardens, if
the seed of the different varieties were not separately saved. When the
eggs of the wild and tame duck are hatched together, the young wild
ducks almost invariably perish, from being of smaller size and not
getting their fair share of food.[39]
Facts in sufficient number have now been given showing that natural
selection often checks, but occasionally favours, man’s power of
selection. These facts teach us, in addition, a valuable lesson,
namely, that we ought to be extremely cautious in judging what
characters are of importance in a state of nature to animals and
plants, which have to struggle for existence from the hour of their
birth to that of their death,—their existence depending on conditions,
about which we are profoundly ignorant.
_Circumstances favourable to Selection by Man._
The possibility of selection rests on variability, and this, as we
shall see in the following chapters, mainly depends on changed
conditions of life, but is governed by infinitely complex and unknown
laws. Domestication, even when long continued, occasionally causes but
a small amount of variability, as in the case of the goose and turkey.
The slight differences, however, which characterise each individual
animal and plant would in most, probably in all, cases suffice for the
production of distinct races through careful and prolonged selection.
We see what selection, though acting on mere individual differences,
can effect when families of cattle, sheep, pigeons, etc., of the same
race, have been separately bred during a number of years by different
men without any wish on their part to modify the breed. We see the same
fact in the difference between hounds bred for hunting in different
districts,[40] and in many other such cases.
In order that selection should produce any result, it is manifest that
the crossing of distinct races must be prevented; hence facility in
pairing, as with the pigeon, is highly favourable for the work; and
difficulty in pairing, as with cats, prevents the formation of distinct
breeds. On nearly the same principle the cattle of the small island of
Jersey have been improved in their milking qualities “with a rapidity
that could not have been obtained in a widely extended country like
France.”[41] Although free crossing is a danger on the one side which
every one can see, too close interbreeding is a hidden danger on the
other side. Unfavourable conditions of life overrule the power of
selection. Our improved heavy breeds of cattle and sheep could not have
been formed on mountainous pastures; nor could dray-horses have been
raised on a barren and inhospitable land, such as the Falkland Islands,
where even the light horses of La Plata rapidly decrease in size. It
seems impossible to preserve several English breeds of sheep in France;
for as soon as the lambs are weaned their vigour decays as the heat of
the summer increases:[42] it would be impossible to give great length
of wool to sheep within the tropics; yet selection has kept the Merino
breed nearly true under diversified and unfavourable conditions. The
power of selection is so great, that breeds of the dog, sheep, and
poultry, of the largest and smallest size, long and short beaked
pigeons, and other breeds with opposite characters, have had their
characteristic qualities augmented, though treated in every way alike,
being exposed to the same climate and fed on the same food. Selection,
however, is either checked or favoured by the effects of use or habit.
Our wonderfully-improved pigs could never have been formed if they had
been forced to search for their own food; the English racehorse and
greyhound could not have been improved up to their present high
standard of excellence without constant training.
As conspicuous deviations of structure occur rarely, the improvement of
each breed is generally the result of the selection of slight
individual differences. Hence the closest attention, the sharpest
powers of observation, and indomitable perseverance, are indispensable.
It is, also, highly important that many individuals of the breed which
is to be improved should be raised; for thus there will be a better
chance of the appearance of variations in the right direction, and
individuals varying in an unfavourable manner may be freely rejected or
destroyed. But that a large number of individuals should be raised, it
is necessary that the conditions of life should favour the propagation
of the species. Had the peacock been reared as easily as the fowl, we
should probably ere this have had many distinct races. We see the
importance of a large number of plants, from the fact of nursery
gardeners almost always beating amateurs in the exhibition of new
varieties. In 1845 it was estimated[43] that between 4000 and 5000
pelargoniums were annually raised from seed in England, yet a decidedly
improved variety is rarely obtained. At Messrs. Carter’s grounds, in
Essex, where such flowers as the Lobelia, Nemophila, Mignonette, etc.,
are grown by the acre for seed, “scarcely a season passes without some
new kinds being raised, or some improvement effected on old kinds.”[44]
At Kew, as Mr. Beaton remarks, where many seedlings of common plants
are raised, “you see new forms of Laburnums, Spiraeas, and other
shrubs.”[45] So with animals: Marshall,[46] in speaking of the sheep in
one part of Yorkshire, remarks, “as they belong to poor people, and are
mostly in small lots, they never can be improved.” Lord Rivers, when
asked how he succeeded in always having first-rate greyhounds,
answered, “I breed many, and hang many.” This, as another man remarks,
“was the secret of his success; and the same will be found in
exhibiting fowls,— successful competitors breed largely, and keep the
best.”[47]
It follows from this that the capacity of breeding at an early age and
at short intervals, as with pigeons, rabbits, etc., facilitates
selection; for the result is thus soon made visible, and perseverance
in the work encouraged. It can hardly be an accident that the great
majority of the culinary and agricultural plants which have yielded
numerous races are annuals or biennials, which therefore are capable of
rapid propagation, and thus of improvement. Sea-kale, asparagus, common
and Jerusalem artichokes, potatoes, and onions, must be excepted, as
they are perennials: but onions are propagated like annuals, and of the
other plants just specified, none, with the exception of the potato,
have yielded in this country more than one or two varieties. In the
Mediterranean region, where artichokes are often raised from seed,
there are several kinds, as I hear from Mr. Bentham. No doubt
fruit-trees, which cannot be propagated quickly by seed, have yielded a
host of varieties, though not permanent races; but these, judging from
prehistoric remains, have been produced at a comparatively late period.
A species may be highly variable, but distinct races will not be
formed, if from any cause selection be not applied. It would be
difficult to select slight variations in fishes from their place of
habitation; and though the carp is extremely variable and is much
attended to in Germany, only one well-marked race has been formed, as I
hear from Lord A. Russell, namely the _spiegel-carpe_; and this is
carefully secluded from the common scaly kind. On the other hand, a
closely allied species, the gold-fish, from being reared in small
vessels, and from having been carefully attended to by the Chinese, has
yielded many races. Neither the bee, which has been semi-domesticated
from an extremely remote period, nor the cochineal insect, which was
cultivated by the aboriginal Mexicans,[48] has yielded races; and it
would be impossible to match the queen-bee with any particular drone,
and most difficult to match cochineal insects. Silk-moths, on the other
hand, have been subjected to rigorous selection, and have produced a
host of races. Cats, which from their nocturnal habits cannot be
selected for breeding, do not, as formerly remarked, yield distinct
races within the same country. Dogs are held in abomination in the
East, and their breeding is neglected; consequently, as Prof. Moritz
Wagner[49] remarks, one kind alone exists there. The ass in England
varies much in colour and size; but as it is an animal of little value
and bred by poor people, there has been no selection, and distinct
races have not been formed. We must not attribute the inferiority of
our asses to climate, for in India they are of even smaller size than
in Europe. But when selection is brought to bear on the ass, all is
changed. Near Cordova, as I am informed (Feb. 1860) by Mr. W. E. Webb,
C.E., they are carefully bred, as much as 200_l._ having been paid for
a stallion ass, and they have been immensely improved. In Kentucky,
asses have been imported (for breeding mules) from Spain, Malta, and
France; these “seldom averaged more than fourteen hands high: but the
Kentuckians, by great care, have raised them up to fifteen hands, and
sometimes even to sixteen. The prices paid for these splendid animals,
for such they really are, will prove how much they are in request. One
male, of great celebrity, was sold for upwards of one thousand pounds
sterling.” These choice asses are sent to cattle-shows, a day being
given for their exhibition.[50]
Analogous facts have been observed with plants: the nutmeg-tree in the
Malay archipelago is highly variable, but there has been no selection,
and there are no distinct races.[51] The common mignonette (_Reseda
odorata_), from bearing inconspicuous flowers, valued solely for their
fragrance, “remains in the same unimproved condition as when first
introduced.”[52] Our common forest-trees are very variable, as may be
seen in every extensive nursery-ground; but as they are not valued like
fruit-trees, and as they seed late in life, no selection has been
applied to them; consequently, as Mr. Patrick Matthews remarks,[53]
they have not yielded distinct races, leafing at different periods,
growing to different sizes, and producing timber fit for different
purposes. We have gained only some fanciful and semi-monstrous
varieties, which no doubt appeared suddenly as we now see them.
Some botanists have argued that plants cannot have so strong a tendency
to vary as is generally supposed, because many species long grown in
botanic gardens, or unintentionally cultivated year after year mingled
with our corn crops, have not produced distinct races; but this is
accounted for by slight variations not having been selected and
propagated. Let a plant which is now grown in a botanic garden, or any
common weed, be cultivated on a large scale, and let a sharp-sighted
gardener look out for each slight variety and sow the seed, and then,
if distinct races are not produced, the argument will be valid.
The importance of selection is likewise shown by considering special
characters. For instance, with most breeds of fowls the form of the
comb and the colour of the plumage have been attended to, and are
eminently characteristic of each race; but in Dorkings fashion has
never demanded uniformity of comb or colour; and the utmost diversity
in these respects prevails. Rose-combs, double-combs, cup-combs, etc.,
and colours of all kinds, may be seen in purely bred and closely
related Dorking fowls, whilst other points, such as the general form of
body, and the presence of an additional toe, have been attended to, and
are invariably present. It has also been ascertained that colour can be
fixed in this breed, as well as in any other.[54]
During the formation or improvement of a breed, its members will always
be found to vary much in those characters to which especial attention
is directed, and of which each slight improvement is eagerly sought and
selected. Thus, with short-faced tumbler-pigeons, the shortness of the
beak, shape of head and plumage,—with carriers, the length of the beak
and wattle,—with fantails, the tail and carriage,—with Spanish fowls,
the white face and comb,—with long-eared rabbits, the length of ear,
are all points which are eminently variable. So it is in every case;
and the large price paid for first-rate animals proves the difficulty
of breeding them up to the highest standard of excellence. This subject
has been discussed by fanciers,[55] and the greater prizes given for
highly improved breeds, in comparison with those given for old breeds
which are not now undergoing rapid improvement, have been fully
justified. Nathusius makes[56] a similar remark when discussing the
less uniform character of improved Shorthorn cattle and of the English
horse, in comparison, for example, with the unennobled cattle of
Hungary, or with the horses of the Asiatic steppes. This want of
uniformity in the parts which at the time are undergoing selection
chiefly depends on the strength of the principle of reversion; but it
likewise depends to a certain extent on the continued variability of
the parts which have recently varied. That the same parts do continue
varying in the same manner we must admit, for if it were not so, there
could be no improvement beyond an early standard of excellence, and we
know that such improvement is not only possible, but is of general
occurrence.
As a consequence of continued variability, and more especially of
reversion, all highly improved races, if neglected or not subjected to
incessant selection, soon degenerate. Youatt gives a curious instance
of this in some cattle formerly kept in Glamorganshire; but in this
case the cattle were not fed with sufficient care. Mr. Baker, in his
memoir on the Horse, sums up: “It must have been observed in the
preceding pages that, whenever there has been neglect, the breed has
proportionally deteriorated.”[57] If a considerable number of improved
cattle, sheep, or other animals of the same race, were allowed to breed
freely together, with no selection, but with no change in their
condition of life, there can be no doubt that after a score or hundred
generations they would be very far from excellent of their kind; but,
from what we see of the many common races of dogs, cattle, fowls,
pigeons, etc., which without any particular care have long retained
nearly the same character, we have no grounds for believing that they
would altogether depart from their type.
It is a general belief amongst breeders that characters of all kinds
become fixed by long-continued inheritance. But I have attempted to
show in the fourteenth chapter that this belief apparently resolves
itself into the following proposition, namely, that all characters
whatever, whether recently acquired or ancient, tend to be transmitted,
but that those which have already long withstood all counteracting
influences, will, as a general rule, continue to withstand them, and
consequently be faithfully transmitted.
_Tendency in Man to carry the practice of Selection to an extreme
point._
It is an important principle that in the process of selection man
almost invariably wishes to go to an extreme point. Thus, there is no
limit to his desire to breed certain kinds of horses and dogs as fleet
as possible, and others as strong as possible; certain kinds of sheep
for extreme fineness, and others for extreme length of wool; and he
wishes to produce fruit, grain, tubers, and other useful parts of
plants, as large and excellent as possible. With animals bred for
amusement, the same principle is even more powerful; for fashion, as we
see in our dress, always runs to extremes. This view has been expressly
admitted by fanciers. Instances were given in the chapters on the
pigeon, but here is another: Mr. Eaton, after describing a
comparatively new variety, namely, the Archangel, remarks, “What
fanciers intend doing with this bird I am at a loss to know, whether
they intend to breed it down to the tumbler’s head and beak, or carry
it out to the carrier’s head and beak; leaving it as they found it, is
not progressing.” Ferguson, speaking of fowls, says, “their
peculiarities, whatever they may be, must necessarily be fully
developed: a little peculiarity forms nought but ugliness, seeing it
violates the existing laws of symmetry.” So Mr. Brent, in discussing
the merits of the sub-varieties of the Belgian canary-bird, remarks,
“Fanciers always go to extremes; they do not admire indefinite
properties.”[58]
This principle, which necessarily leads to divergence of character,
explains the present state of various domestic races. We can thus see
how it is that racehorses and dray-horses, greyhounds and mastiffs,
which are opposed to each other in every character,—how varieties so
distinct as Cochin-china fowls and bantams, or carrier-pigeons with
very long beaks, and tumblers with excessively short beaks, have been
derived from the same stock. As each breed is slowly improved, the
inferior varieties are first neglected and finally lost. In a few
cases, by the aid of old records, or from intermediate varieties still
existing in countries where other fashions have prevailed, we are
enabled partially to trace the graduated changes through which certain
breeds have passed. Selection, whether methodical or unconscious,
always tending towards an extreme point, together with the neglect and
slow extinction of the intermediate and less-valued forms, is the key
which unlocks the mystery of how man has produced such wonderful
results.
In a few instances selection, guided by utility for a single purpose,
has led to convergence of character. All the improved and different
races of the pig, as Nathusius has well shown,[59] closely approach
each other in character, in their shortened legs and muzzles, their
almost hairless, large, rounded bodies, and small tusks. We see some
degree of convergence in the similar outline of the body in well-bred
cattle belonging to distinct races.[60] I know of no other such cases.
Continued divergence of character depends on, and is indeed a clear
proof, as previously remarked, of the same parts continuing to vary in
the same direction. The tendency to mere general variability or
plasticity of organisation can certainly be inherited, even from one
parent, as has been shown by Gärtner and Kölreuter, in the production
of varying hybrids from two species, of which one alone was variable.
It is in itself probable that, when an organ has varied in any manner,
it will again vary in the same manner, if the conditions which first
caused the being to vary remain, as far as can be judged, the same.
This is either tacitly or expressly admitted by all horticulturists: if
a gardener observes one or two additional petals in a flower, he feels
confident that in a few generations he will be able to raise a double
flower, crowded with petals. Some of the seedlings from the weeping
Moccas oak were so prostrate that they only crawled along the ground. A
seedling from the fastigiate or upright Irish yew is described as
differing greatly from the parent-form “by the exaggeration of the
fastigiate habit of its branches.”[61] Mr. Shirreff, who has been
highly successful in raising new kinds of wheat, remarks, “A good
variety may safely be regarded as the forerunner of a better one.”[62]
A great rose-grower, Mr. Rivers, has made the same remark with respect
to roses. Sageret,[63] who had large experience, in speaking of the
future progress of fruit-trees, observes that the most important
principle is “that the more plants have departed from their original
type, the more they tend to depart from it.” There is apparently much
truth in this remark; for we can in no other way understand the
surprising amount of difference between varieties in the parts or
qualities which are valued, whilst other parts retain nearly their
original character.
The foregoing discussion naturally leads to the question, what is the
limit to the possible amount of variation in any part or quality, and,
consequently, is there any limit to what selection can effect? Will a
racehorse ever be reared fleeter than Eclipse? Can our prize-cattle and
sheep be still further improved? Will a gooseberry ever weigh more than
that produced by “London” in 1852? Will the beet-root in France yield a
greater percentage of sugar? Will future varieties of wheat and other
grain produce heavier crops than our present varieties? These questions
cannot be positively answered; but it is certain that we ought to be
cautious in answering them by a negative. In some lines of variation
the limit has probably been reached. Youatt believes that the reduction
of bone in some of our sheep has already been carried so far that it
entails great delicacy of constitution.[64] But seeing the great
improvement within recent times in our cattle and sheep, and especially
in our pigs; seeing the wonderful increase in weight in our poultry of
all kinds during the last few years; he would be a bold man who would
assert that perfection has been reached. It has often been said that
Eclipse never was, and never will be, beaten in speed by any other
horse; but on making inquiries I find that the best judges believe that
our present racehorses are fleeter.[65] The attempt to raise a new
variety of wheat more productive than the many old kinds, might have
been thought until lately quite hopeless; but this has been effected by
Major Hallett, by careful selection. With respect to almost all our
animals and plants, those who are best qualified to judge do not
believe that the extreme point of perfection has yet been reached even
in the characters which have already been carried to a high standard.
For instance, the short-faced tumbler-pigeon has been greatly modified;
nevertheless, according to Mr. Eaton[66] “the field is still as open
for fresh competitors as it was one hundred years ago.” Over and over
again it has been said that perfection had been attained with our
flowers, but a higher standard has soon been reached. Hardly any fruit
has been more improved than the strawberry, yet a great authority
remarks,[67] “it must not be concealed that we are far from the extreme
limits at which we may arrive.”
No doubt there is a limit beyond which the organisation cannot be
modified compatibly with health or life. The extreme degree of
fleetness, for instance, of which a terrestrial animal is capable, may
have been acquired by our present racehorses; but as Mr. Wallace has
well remarked,[68] the question that interests us, “is not whether
indefinite and unlimited change in any or all directions is possible,
but whether such differences as do occur in nature could have been
produced by the accumulation of varieties by selection.” And in the
case of our domestic productions, there can be no doubt that many parts
of the organisation, to which man has attended, have been thus modified
to a greater degree than the corresponding parts in the natural species
of the same genera or even families. We see this in the form and size
of our light and heavy dogs or horses,—in the beak and many other
characters of our pigeons,—in the size and quality of many fruits,—in
comparison with the species belonging to the same natural groups.
Time is an important element in the formation of our domestic races, as
it permits innumerable individuals to be born, and these when exposed
to diversified conditions are rendered variable. Methodical selection
has been occasionally practised from an ancient period to the present
day, even by semi-civilised people, and during former times will have
produced some effect. Unconscious selection will have been still more
effective; for during a lengthened period the more valuable individual
animals will occasionally have been saved, and the less valuable
neglected. In the course of time, different varieties, especially in
the less civilised countries, will also have been more or less modified
through natural selection. It is generally believed, though on this
head we have little or no evidence, that new characters in time become
fixed; and after having long remained fixed it seems possible that
under new conditions they might again be rendered variable.
How great the lapse of time has been since man first domesticated
animals and cultivated plants, we begin dimly to see. When the
lake-dwellings of Switzerland were inhabited during the Neolithic
period, several animals were already domesticated and various plants
cultivated. The science of language tells us that the art of ploughing
and sowing the land was followed, and the chief animals had been
already domesticated, at an epoch so immensely remote, that the
Sanskrit, Greek, Latin, Gothic, Celtic, and Sclavonic languages had not
as yet diverged from their common parent-tongue.[69]
It is scarcely possible to overrate the effects of selection
occasionally carried on in various ways and places during thousands of
generations. All that we know, and, in a still stronger degree, all
that we do not know,[70] of the history of the great majority of our
breeds, even of our more modern breeds, agrees with the view that their
production, through the action of unconscious and methodical selection,
has been almost insensibly slow. When a man attends rather more closely
than is usual to the breeding of his animals, he is almost sure to
improve them to a slight extent. They are in consequence valued in his
immediate neighbourhood, and are bred by others; and their
characteristic features, whatever these may be, will then slowly but
steadily be increased, sometimes by methodical and almost always by
unconscious selection. At last a strain, deserving to be called a
sub-variety, becomes a little more widely known, receives a local name,
and spreads. The spreading will have been extremely slow during ancient
and less civilised times, but now is rapid. By the time that the new
breed had assumed a somewhat distinct character, its history, hardly
noticed at the time, will have been completely forgotten; for, as Low
remarks,[71] “we know how quickly the memory of such events is
effaced.”
As soon as a new breed is thus formed, it is liable through the same
process to break up into new strains and sub-varieties. For different
varieties are suited for, and are valued under, different
circumstances. Fashion changes, but, should a fashion last for even a
moderate length of time, so strong is the principle of inheritance,
that some effect will probably be impressed on the breed. Thus
varieties go on increasing in number, and history shows us how
wonderfully they have increased since the earliest records.[72] As each
new variety is produced, the earlier, intermediate, and less valuable
forms will be neglected, and perish. When a breed, from not being
valued, is kept in small numbers, its extinction almost inevitably
follows sooner or later, either from accidental causes of destruction
or from close interbreeding; and this is an event which, in the case of
well-marked breeds, excites attention. The birth or production of a new
domestic race is so slow a process that it escapes notice; its death or
destruction is comparatively sudden, is often recorded, and when too
late sometimes regretted.
Several authors have drawn a wide distinction between artificial and
natural races. The latter are more uniform in character, possessing in
a high degree the appearance of natural species, and are of ancient
origin. They are generally found in less civilised countries, and have
probably been largely modified by natural selection, and only to a
small extent by man’s unconscious and methodical selection. They have,
also, during a long period, been directly acted on by the physical
conditions of the countries which they inhabit. The so-called
artificial races, on the other hand, are not so uniform in character;
some have a semi-monstrous character, such as “the wry-legged terriers
so useful in rabbit-shooting,”[73] turnspit dogs, ancon sheep, niata
oxen, Polish fowls, fantail-pigeons, etc.; their characteristic
features have generally been acquired suddenly, though subsequently
increased by careful selections in many cases. Other races, which
certainly must be called artificial, for they have been largely
modified by methodical selection and by crossing, as the English
racehorse, terrier-dogs, the English game-cock, Antwerp
carrier-pigeons, etc., nevertheless cannot be said to have an unnatural
appearance; and no distinct line, as it seems to me, can be drawn
between natural and artificial races.
It is not surprising that domestic races should generally present a
different aspect from natural species. Man selects and propagates
modifications solely for his own use or fancy, and not for the
creature’s own good. His attention is struck by strongly marked
modifications, which have appeared suddenly, due to some great
disturbing cause in the organisation. He attends almost exclusively to
external characters; and when he succeeds in modifying internal
organs,—when for instance he reduces the bones and offal, or loads the
viscera with fat, or gives early maturity, etc.-the chances are strong
that he will at the same time weaken the constitution. On the other
hand, when an animal has to struggle throughout its life with many
competitors and enemies, under circumstances inconceivably complex and
liable to change, modifications of the most varied nature in the
internal organs as well as in external characters, in the functions and
mutual relations of parts, will be rigorously tested, preserved, or
rejected. Natural selection often checks man’s comparatively feeble and
capricious attempts at improvement; and if it were not so, the result
of his work, and of nature’s work, would be even still more different.
Nevertheless, we must not overrate the amount of difference between
natural species and domestic races; the most experienced naturalists
have often disputed whether the latter are descended from one or from
several aboriginal stocks, and this clearly shows that there is no
palpable difference between species and races.
Domestic races propagate their kind far more truly, and endure for
munch longer periods, than most naturalists are willing to admit.
Breeders feel no doubt on this head: ask a man who has long reared
Shorthorn or Hereford cattle, Leicester or Southdown sheep, Spanish or
Game poultry, tumbler or carrier-pigeons, whether these races may not
have been derived from common progenitors, and he will probably laugh
you to scorn. The breeder admits that he may hope to produce sheep with
finer or longer wool and with better carcases, or handsomer fowls, or
carrier-pigeons with beaks just perceptibly longer to the practised
eye, and thus be successful at an exhibition. Thus far he will go, but
no farther. He does not reflect on what follows from adding up during a
long course of time many slight, successive modifications; nor does he
reflect on the former existence of numerous varieties, connecting the
links in each divergent line of descent. He concludes, as was shown in
the earlier chapters, that all the chief breeds to which he has long
attended are aboriginal productions. The systematic naturalist, on the
other hand, who generally knows nothing of the art of breeding, who
does not pretend to know how and when the several domestic races were
formed, who cannot have seen the intermediate gradations, for they do
not now exist, nevertheless feels no doubt that these races are sprung
from a single source. But ask him whether the closely allied natural
species which he has studied may not have descended from a common
progenitor, and he in his turn will perhaps reject the notion with
scorn. Thus the naturalist and breeder may mutually learn a useful
lesson from each other.
_Summary on Selection by Man._—There can be no doubt that methodical
selection has effected and will effect wonderful results. It was
occasionally practised in ancient times, and is still practised by
semi-civilised people. Characters of the highest importance, and others
of trifling value, have been attended to, and modified. I need not here
repeat what has been so often said on the part which unconscious
selection has played: we see its power in the difference between flocks
which have been separately bred, and in the slow changes, as
circumstances have slowly changed, which many animals have undergone in
the same country, or when transported into a foreign land. We see the
combined effects of methodical and unconscious selection, in the great
amount of difference in those parts or qualities which are valued by
man in comparison with the parts which are not valued, and consequently
have not been attended to. Natural selection often determines man’s
power of selection. We sometimes err in imagining that characters,
which are considered as unimportant by the systematic naturalist, could
not be affected by the struggle for existence, and could not be acted
on by natural selection; but striking cases have been given, showing
how great an error this is.
The possibility of selection coming into action rests on variability;
and this is mainly caused, as we shall hereafter see, by changes in the
conditions of life. Selection is sometimes rendered difficult, or even
impossible, by the conditions being opposed to the desired character or
quality. It is sometimes checked by the lessened fertility and weakened
constitution which follow from long-continued close interbreeding. That
methodical selection may be successful, the closest attention and
discernment, combined with unwearied patience, are absolutely
necessary; and these same qualities, though not indispensable, are
highly serviceable in the case of unconscious selection. It is almost
necessary that a large number of individuals should be reared; for thus
there will be a fair chance of variations of the desired nature
arising, and of every individual with the slightest blemish or in any
degree inferior being freely rejected. Hence length of time is an
important element of success. Thus, also, reproduction at an early age
and at short intervals favours the work. Facility in pairing animals,
or their inhabiting a confined area, is advantageous as a check to free
crossing. Whenever and wherever selection is not practised, distinct
races are not formed within the same country. When any one part of the
body or one quality is not attended to, it remains either unchanged or
varies in a fluctuating manner, whilst at the same time other parts and
other qualities may become permanently and greatly modified. But from
the tendency to reversion and to continued variability, those parts or
organs which are now undergoing rapid improvement through selection,
are likewise found to vary much. Consequently highly-bred animals when
neglected soon degenerate; but we have no reason to believe that the
effects of long-continued selection would, if the conditions of life
remained the same, be soon and completely lost.
Man always tends to go to an extreme point in the selection, whether
methodical or unconscious, of all useful and pleasing qualities. This
is an important principle, as it leads to continued divergence, and in
some rare cases to convergence of character. The possibility of
continued divergence rests on the tendency in each part or organ to go
on varying in the same manner in which it has already varied; and that
this occurs, is proved by the steady and gradual improvement of many
animals and plants during lengthened periods. The principle of
divergence of character, combined with the neglect and final extinction
of all previous, less-valued, and intermediate varieties, explains the
amount of difference and the distinctness of our several races.
Although we may have reached the utmost limit to which certain
characters can be modified, yet we are far from having reached, as we
have good reason to believe, the limit in the majority of cases.
Finally, from the difference between selection as carried on by man and
by nature, we can understand how it is that domestic races often,
though by no means always, differ in general aspect from closely allied
natural species.
Throughout this chapter and elsewhere I have spoken of selection as the
paramount power, yet its action absolutely depends on what we in our
ignorance call spontaneous or accidental variability. Let an architect
be compelled to build an edifice with uncut stones, fallen from a
precipice. The shape of each fragment may be called accidental; yet the
shape of each has been determined by the force of gravity, the nature
of the rock, and the slope of the precipice,—events and circumstances,
all of which depend on natural laws; but there is no relation between
these laws and the purpose for which each fragment is used by the
builder. In the same manner the variations of each creature are
determined by fixed and immutable laws; but these bear no relation to
the living structure which is slowly built up through the power of
selection, whether this be natural or artificial selection.
If our architect succeeded in rearing a noble edifice, using the rough
wedge-shaped fragments for the arches, the longer stones for the
lintels, and so forth, we should admire his skill even in a higher
degree than if he had used stones shaped for the purpose. So it is with
selection, whether applied by man or by nature; for although
variability is indispensably necessary, yet, when we look at some
highly complex and excellently adapted organism, variability sinks to a
quite subordinate position in importance in comparison with selection,
in the same manner as the shape of each fragment used by our supposed
architect is unimportant in comparison with his skill.
REFERENCES
[1] Quoted by Youatt on Sheep, p. 325. _See also_ Youatt on Cattle,
pp. 62, 69.
[2] MM. Lherbette and De Quatrefages, in ‘Bull. Soc. d’Acclimat.,’
tom. viii. 1861, p. 311.
[3] ‘The Poultry Book,’ 1866, p. 123. Mr. Tegetmeier, ‘The Homing or
Carrier Pigeon,’ 1871, pp. 45-58.
[4] Youatt on Sheep, p. 312.
[5] ‘Treatise on the Almond Tumbler,’ 1851, p. 33.
[6] Dr. Heusinger, ‘Wochenschrift für die Heilkunde,’ Berlin, 1846, s.
279.
[7] Youatt on the Dog, p. 232.
[8] ‘The Fruit-trees of America,’ 1845, p. 270: for peaches, p. 466.
[9] ‘Proc. Royal Soc. of Arts and Sciences of Mauritius,’ 1852, p.
135.
[10] ‘Gardener’s Chronicle,’ 1856, p. 379.
[11] Quatrefages, ‘Maladies Actuelles du Ver à Soie,’ 1859, pp. 12,
214.
[12] ‘Gardener’s Chronicle,’ 1851, p. 595.
[13] ‘Journal of Horticulture,’ 1862, p. 476.
[14] ‘Gardener’s Chronicle,’ 1852, pp. 435, 691.
[15] Bechstein, ‘Naturgesch. Deutschlands,’ 1801, B. 1 s. 310.
[16] Prichard, ‘Phys. Hist. of Mankind,’ 1851, vol. i. p. 224.
[17] G. Lewis’s ‘Journal of Residence in West Indies,’ ‘Home and Col.
Library,’ p. 100.
[18] Sidney’s edition of Youatt on the Pig, p. 24. I have given
analogous facts in the case of mankind in my ‘Descent of Man,’ 2nd
edit., p. 195.
[19] ‘Journal of Horticulture,’ 1862, pp. 476, 498; 1865, p. 460. With
respect to the heartsease, ‘Gardener’s Chronicle,’ 1863, p. 628.
[20] ‘Des Jacinthes, de leur Culture,’ 1768, p. 53: on wheat
‘Gardener’s Chronicle,’ 1846, p. 653.
[21] W. B. Tegetmeier, ‘The Field,’ Feb. 25, 1865. With respect to
black fowls, _see_ a quotation in Thompson’s ‘Nat. Hist. of Ireland,’
1849, vol. i. p. 22.
[22] ‘In Sachen Darwin’s contra Wigand,’ 1874, p. 70.
[23] ‘Bull. de la Soc. d’Acclimat.,’ tom. vii. 1860, p. 359.
[24] ‘Transact. Hort. Soc.,’ vol. i. 2nd series, 1835, p. 275. For
raspberries, _see_ ‘Gardener’s Chronicle,’ 1855, p. 154, and 1863 p.
245.
[25] ‘Gardener’s Chronicle,’ 1843, p. 806.
[26] Ibid., 1850, p. 732.
[27] Ibid., 1860, p. 956.
[28] J. De Jonghe, in ‘Gardener’s Chronicle,’ 1860, p. 120.
[29] Downing, ‘Fruit-trees of North America,’ pp. 266, 501: in regard
to the cherry, p. 198.
[30] ‘Gardener’s Chronicle,’ 1849, p. 755.
[31] ‘Journal of Horticulture,’ Sept. 26th, 1865, p. 254; _ see_ other
references given in chap. x.
[32] Mr. Selby, in ‘Mag. of Zoology and Botany,’ Edinburgh, vol. ii.
1838, p. 393.
[33] The Reine Claude de Bavay, ‘Journal of Horticulture,’ Dec. 27,
1864, p. 511.
[34] Mr. Pusey, in ‘Journal of R. Agricult. Soc.,’ vol. vi. p. 179.
For Swedish turnips, _see_ ‘Gardener’s Chronicle,’ 1847, p. 91.
[35] Godron, ‘De l’Espèce,’ tom. ii. p. 98.
[36] ‘Gardener’s Chronicle,’ 1866, p. 732.
[37] ‘Gardener’s Chronicle,’ 1862, pp. 820, 821.
[38] ‘On the Varieties of Wheat,’ p. 59.
[39] Mr. Hewitt and others, in ‘Journal of Hort.,’ 1862, p. 773.
[40] ‘Encyclop. of Rural Sports,’ p. 405.
[41] Col. Le Couteur, ‘Journal Roy. Agricult. Soc.,’ vol. iv. p. 43.
[42] Malingié-Nouel, ‘Journal R. Agricult. Soc.,’ vol. xiv. 1853, pp.
215, 217.
[43] ‘Gardener’s Chronicle,’ 1845, p. 273.
[44] ‘Journal of Horticulture,’ 1862, p. 157.
[45] ‘Cottage Gardener,’ 1860, p. 368.
[46] ‘A Review of Reports,’ 1808, p. 406.
[47] ‘Gardener’s Chronicle,’ 1853, p. 45.
[48] Isidore Geoffroy Saint-Hilaire, ‘Hist. Nat. Gen.,’ tom. iii. p.
49. ‘On the Cochineal Insect,’ p. 46.
[49] ‘Die Darwin’sche Theorie und das Migrationsgesetz der
Organismen,’ 1868, p. 19.
[50] Capt. Marryat, quoted by Blyth in ‘Journ. Asiatic Soc. of
Bengal,’ vol. xxviii. p. 229.
[51] Mr. Oxley, ‘Journal of the Indian Archipelago,’ vol. ii. 1848, p.
645.
[52] Mr. Abbey, ‘Journal of Horticulture,’ Dec. 1, 1863, p. 430.
[53] ‘On Naval Timber,’ 1831, p. 107.
[54] Mr. Baily, in ‘The Poultry Chronicle,’ vol. ii. 1854, p. 150.
Also vol. i. p. 342; vol. iii. p. 245.
[55] ‘Cottage Gardener,’ 1855, December, p. 171; 1856, January, pp.
248, 323.
[56] ‘Ueber Shorthorn Rindvieh,’ 1857, s. 51.
[57] ‘The Veterinary,’ vol. xiii. p. 720. For the Glamorganshire
cattle, _see_ Youatt on Cattle, p. 51.
[58] J. M. Eaton, ‘A Treatise on Fancy Pigeons,’ p. 82; Ferguson, on
‘Rare and Prize Poultry,’ p. 162; Mr. Brent, in ‘Cottage Gardener,’
Oct. 1860, p. 13.
[59] ‘Die Racen des Schweines,’ 1860, s. 48.
[60] _See_ some good remarks on this head by M. de Quatrefages, ‘Unité
de l’Espèce Humaine,’ 1861, p. 119.
[61] Verlot, ‘Des Variétés,’ 1865, p. 94.
[62] Mr. Patrick Shirreff, in ‘Gardener’s Chronicle,’ 1858, p. 771.
[63] ‘Pomologie Physiolog.,’ 1830, p. 106.
[64] Youatt on Sheep, p. 521.
[65] _See also_ Stonehenge, ‘British Rural Sports,’ edition of 1871,
p. 384.
[66] ‘A Treatise on the Almond Tumbler,’ p. 1.
[67] M. J. de Jonghe, in ‘Gardener’s Chronicle,’ 1858, p. 173.
[68] ‘Contributions to the Theory of Natural Selection,’ 2nd edit.,
1871, p. 292.
[69] Max Müller, ‘Science of Language,’ 1861, p. 223.
[70] Youatt on Cattle, pp. 116, 128.
[71] ‘Domesticated Animals,’ p. 188.
[72] Volz, ‘Beiträge zur Kulturgeschichte,’ 1852, s. 99 _et passim._
[73] Blaine, ‘Encyclop. of Rural Sports,’ p. 213.