DUCK—GOOSE—PEACOCK—TURKEY—GUINEA-FOWL—CANARY-BIRD—GOLD-FISH—RIVER-BEES—
SILK-MOTHS.
DUCKS, SEVERAL BREEDS OF—PROGRESS OF DOMESTICATION—ORIGIN OF FROM THE
COMMON WILD-DUCK—DIFFERENCES IN THE DIFFERENT BREEDS—OSTEOLOGICAL
DIFFERENCES—EFFECTS OF USE AND DISUSE ON THE LIMB-BONES.
GOOSE, ANCIENTLY DOMESTICATED—LITTLE VARIATION OF—SEBASTOPOL BREED.
PEACOCK, ORIGIN OF BLACK-SHOULDERED BREED.
TURKEY,BREEDS OF—CROSSED WITH THE UNITED STATES SPECIES—EFFECTS OF
CLIMATE ON.
GUINEA-FOWL, CANARY-BIRD, GOLD-FISH, HIVE-BEES.
SILK-MOTHS, SPECIES AND BREEDS OF—ANCIENTLY DOMESTICATED—CARE IN THEIR
SELECTION—DIFFERENCES IN THE DIFFERENT RACES—IN THE EGG, CATERPILLAR,
AND COCOON STATES—INHERITANCE OF CHARACTERS—IMPERFECT WINGS—LOST
INSTINCTS—CORRELATED CHARACTERS.
I will, as in previous cases, first briefly describe the chief domestic
breeds of the duck:—
BREED 1. _Common Domestic Duck._—Varies much in colour and in
proportions, and differs in instincts and disposition from the wild
duck. There are several sub-breeds:—(1) The Aylesbury, of great size,
white, with pale-yellow beak and legs; abdominal dermal sack largely
developed. (2) The Rouen, of great size, coloured like the wild duck,
with green or mottled beak; dermal sack largely developed. (3) Tufted
Duck, with a large top-knot of fine downy feathers, supported on a
fleshy mass, with the skull perforated beneath. The top-knot in a duck
which I imported from Holland was two and a half inches in diameter.
(4) Labrador (or Canadian, or Buenos Ayres, or East Indian); plumage
entirely black; beak broader, relatively to its length, than in the
wild duck; eggs slightly tinted with black. This sub-breed perhaps
ought to be ranked as a breed; it includes two sub-varieties, one as
large as the common domestic duck, which I have kept alive, and the
other smaller and often capable of flight.[1] I presume it is this
latter sub-variety which has been described in France[2] as flying
well, being rather wild, and when cooked having the flavour of the wild
duck; nevertheless this sub-variety is polygamous, like other
domesticated ducks and unlike the wild duck. These black Labrador ducks
breed true; but a case is given by Dr. Turral of the French sub-variety
producing young with some white feathers on the head and neck, and with
an ochre-coloured patch on the breast.
BREED 2. _Hook-billed Duck._—This bird presents an extraordinary
appearance from the downward curvature of the beak. The head is often
tufted. The common colour is white, but some are coloured like wild
ducks. It is an ancient breed, having been noticed in 1676.[3] It shows
its prolonged domestication by almost incessantly laying eggs, like the
fowls which are called everlasting layers.[4]
BREED 3. _Call Duck._—Remarkable from its small size, and from the
extraordinary loquacity of the female. Beak short. These birds are
either white, or coloured like the wild duck.
BREED 4. _Penguin Duck._—This is the most remarkable of all the breeds,
and seems to have originated in the Malayan archipelago. It walks with
its body extremely erect, and with its thin neck stretched straight
upwards. Beak rather short. Tail upturned, including only 18 feathers.
Femur and metatarsus elongated.
Almost all naturalists admit that the several breeds are descended from
the common wild duck (_Anas boschas_); most fanciers, on the other
hand, take as usual a very different view.[5] Unless we deny that
domestication, prolonged during centuries, can affect even such
unimportant characters as colour, size, and in a slight degree
proportional dimensions and mental disposition, there is no reason
whatever to doubt that the domestic duck is descended from the common
wild species, for the one differs from the other in no important
character. We have some historical evidence with respect to the period
and progress of the domestication of the duck. It was unknown[6] to the
ancient Egyptians, to the Jews of the Old Testament, and to the Greeks
of the Homeric period. About eighteen centuries ago Columella[7] and
Varro speak of the necessity of keeping ducks in netted enclosures like
other wild fowl, so that at this period there was danger of their
flying away. Moreover, the plan recommended by Columella to those who
wish to increase their stock of ducks, namely, to collect the eggs of
the wild bird and to place them under a hen, shows, as Mr. Dixon
remarks, “that the duck had not at this time become a naturalised and
prolific inmate of the Roman poultry-yard.” The origin of the domestic
duck from the wild species is recognised in nearly every language of
Europe, as Aldrovandi long ago remarked, by the same name being applied
to both. The wild duck has a wide range from the Himalayas to North
America. It crosses readily with the domestic bird, and the crossed
offspring are perfectly fertile.
Both in North America and Europe the wild duck has been found easy to
tame and breed. In Sweden this experiment was carefully tried by
Tiburtius; he succeeded in rearing wild ducks for three generations,
but, though they were treated like common ducks, they did not vary even
in a single feather. The young birds suffered from being allowed to
swim about in cold water,[8] as is known to be the case, though the
fact is a strange one, with the young of the common domestic duck. An
accurate and well-known observer in England[9] has described in detail
his often repeated and successful experiments in domesticating the wild
duck. Young birds are easily reared from eggs hatched under a bantam;
but to succeed it is indispensable not to place the eggs of both the
wild and tame duck under the same hen, for in this case “the young wild
ducks die off, leaving their more hardy brethren in undisturbed
possession of their foster-mother’s care. The difference of habit at
the onset in the newly-hatched ducklings almost entails such a result
to a certainty.” The wild ducklings were from the first quite tame
towards those who took care of them as long as they wore the same
clothes, and likewise to the dogs and cats of the house. They would
even snap with their beaks at the dogs, and drive them away from any
spot which they coveted. But they were much alarmed at strange men and
dogs. Differently from what occurred in Sweden, Mr. Hewitt found that
his young birds always changed and deteriorated in character in the
course of two or three generations; notwithstanding that great care was
taken to prevent their crossing with tame ducks. After the third
generation his birds lost the elegant carriage of the wild species, and
began to acquire the gait of the common duck. They increased in size in
each generation, and their legs became less fine. The white collar
round the neck of the mallard became broader and less regular, and some
of the longer primary wing-feathers became more or less white. When
this occurred, Mr. Hewitt destroyed nearly the whole of his stock and
procured fresh eggs from wild nests; so that he never bred the same
family for more than five or six generations. His birds continued to
pair together, and never became polygamous like the common domestic
duck. I have given these details, because no other case, as far as I
know, has been so carefully recorded by a competent observer of the
progress of change in wild birds reared for several generations in a
domestic condition.
From these considerations there can hardly be a doubt that the wild
duck is the parent of the common domestic kind; nor need we look to
other species for the parentage of the more distinct breeds, namely,
Penguin, Call, Hook-billed, Tufted, and Labrador ducks. I will not
repeat the arguments used in the previous chapters on the improbability
of man having in ancient times domesticated several species since
become unknown or extinct, though ducks are not readily exterminated in
the wild state;—on some of the supposed parent-species having had
abnormal characters in comparison with all the other species of the
genus, as with Hook-billed and Penguin ducks;—on all the breeds, as far
as is known being fertile together;[10]—on all the breeds having the
same general disposition, instinct, etc. But one fact bearing on this
question may be noticed: in the great duck family, one species alone,
namely, the male of _A. boschas,_ has its four middle tail-feathers
curled upwardly; now in every one of the above-named domestic breeds
these curled feathers exist, and on the supposition that they are
descended from distinct species, we must assume that man formerly hit
upon species all of which had this now unique character. Moreover,
sub-varieties of each breed are coloured almost exactly like the wild
duck, as I have seen with the largest and smallest breeds, namely
Rouens and Call ducks, and, as Mr. Brent states,[11] is the case with
Hook-billed ducks. This gentleman, as he informs me, crossed a white
Aylesbury drake and a black Labrador duck, and some of the ducklings as
they grew up assumed the plumage of the wild duck.
With respect to Penguins, I have not seen many specimens, and none were
coloured precisely like the wild duck; but Sir James Brooke sent me
three skins from Lombok and Bali, in the Malayan archipelago; the two
females were paler and more rufous than the wild duck, and the drake
differed in having the whole under and upper surface (excepting the
neck, tail-coverts, tail, and wings) silver-grey, finely pencilled with
dark lines, closely like certain parts of the plumage of the wild
mallard. But I found this drake to be identical in every feather with a
variety of the common breed procured from a farm-yard in Kent, and I
have occasionally elsewhere seen similar specimens. The occurrence of a
duck bred under so peculiar a climate as that of the Malayan
archipelago, where the wild species does not exist, with exactly the
same plumage as may occasionally be seen in our farm-yards, is a fact
worth notice. Nevertheless the climate of the Malayan archipelago
apparently tends to cause the duck to vary much, for Zollinger,[12]
speaking of the Penguin breed, says that in Lombok “there is an unusual
and very wonderful variety of ducks.” One Penguin drake which I kept
alive differed from those of which the skins were sent me from Lombok,
in having its breast and back partially coloured with chestnut-brown,
thus more closely resembling the Mallard.
From these several facts, more especially from the drakes of all the
breeds having curled tail-feathers, and from certain sub-varieties in
each breed occasionally resembling in general plumage the wild duck, we
may conclude with confidence that all the breeds are descended from _A.
boschas._
I will now notice some of the peculiarities characteristic of the
several breeds. The eggs vary in colour; some common ducks laying
pale-greenish and others quite white eggs. The eggs which are first
laid during each season by the black Labrador duck, are tinted black,
as if rubbed with ink. A good observer assured me that one year his
ducks of this breed laid almost perfectly white eggs. Another curious
case shows what singular variations sometimes occur and are inherited;
Mr. Hansell[13] relates that he had a common duck which always laid
eggs with the yolk of a dark-brown colour like melted glue; and the
young ducks, hatched from these eggs, laid the same kind of eggs, so
that the breed had to be destroyed.
Illustration: Fig 39—Skulls of Ducks, viewed laterally.
A. Wild Duck. B. Hook-billed Duck.
The Hook-billed duck is highly remarkable (see fig. 39, of skull); and
its peculiar beak has been inherited at least since the year 1676. This
structure is evidently analogous with that described in the Bagadotten
carrier pigeon. Mr. Brent[14] says that, when Hook-billed ducks are
crossed with common ducks, “many young ones are produced with the upper
mandible shorter than the lower, which not unfrequently causes the
death of the bird.” With ducks a tuft of feathers on the head is by no
means a rare occurrence; namely, in the True-tufted breed, the
Hook-billed, the common farm-yard kind, and in a duck having no other
peculiarity which was sent to me from the Malayan archipelago. The tuft
is only so far interesting as it affects the skull, which is thus
rendered slightly more globular, and is perforated by numerous
apertures. Call ducks are remarkable from their extraordinary
loquacity: the drake only hisses like common drakes; nevertheless, when
paired with the common duck, he transmits to his female offspring a
strong quacking tendency. This loquacity seems at first a surprising
character to have been acquired under domestication. But the voice
varies in the different breeds; Mr. Brent[15] says that Hook-billed
ducks are very loquacious, and that Rouens utter a “dull, loud, and
monotonous cry, easily distinguishable by an experienced ear.” As the
loquacity of the Call duck is highly serviceable, these birds being
used in decoys, this quality may have been increased by selection. For
instance, Colonel Hawker says, if young wild ducks cannot be got for a
decoy, “by way of make-shift, _select_ tame birds which are the most
clamorous, even if their colour should not be like that of wild
ones.”[16] It has been erroneously asserted that Call ducks hatch their
eggs in less time than common ducks.[17]
The Penguin duck is the most remarkable of all the breeds; the thin
neck and body are carried erect; the wings are small; the tail is
upturned; and the thigh-bones and metatarsi are considerably lengthened
in proportion with the same bones in the wild duck. In five specimens
examined by me there were only eighteen tail-feathers instead of twenty
as in the wild duck; but I have also found only eighteen and nineteen
tail-feathers in two Labrador ducks. On the middle toe, in three
specimens, there were twenty-seven or twenty-eight scutellæ, whereas in
two wild ducks there were thirty-one and thirty-two. The Penguin when
crossed transmits with much power its peculiar form of body and gait to
its offspring; this was manifest with some hybrids raised in the
Zoological Gardens between one of these birds and the Egyptian
goose,[18] (_Anser ægyptiacus_) and likewise with some mongrels which I
raised between the Penguin and Labrador duck. I am not much surprised
that some writers should maintain that this breed must be descended
from an unknown and distinct species; but from the reasons already
assigned, it seems to me far more probable that it is the descendant,
much modified by domestication under an unnatural climate, of _Anas
boschas._
_Osteological Characters._—The skulls of the several breeds differ from
each other and from the skull of the wild duck in very little except in
the proportional length and curvature of the premaxillaries. These
latter bones in the Call duck are short, and a line drawn from their
extremities to the summit of the skull is nearly straight, instead of
being concave as in the common duck; so that the skull resembles that
of a small goose. In the Hook-billed duck (fig. 39), these same bones
as well as the lower jaw curve downwards in a most remarkable manner,
as represented. In the Labrador duck the premaxillaries are rather
broader than in the wild duck; and in two skulls of this breed the
vertical ridges on each side of the supra-occipital bone are very
prominent. In the Penguin the premaxillaries are relatively shorter
than in the wild duck; and the inferior points of the paramastoids more
prominent. In a Dutch tufted duck, the skull under the enormous tuft
was slightly more globular and was perforated by two large apertures;
in this skull the lachrymal bones were produced much further backwards,
so as to have a different shape and nearly to touch the post. lat.
processes of the frontal bones, thus almost completing the bony orbit
of the eye. As the quadrate and pterygoid bones are of such complex
shape and stand in relation with so many other bones, I carefully
compared them in all the principal breeds; but excepting in size they
presented no difference.
Illustration: Fig 40—Cervical Verterbræ of Ducks.
_Vertebræ and Ribs._—In one skeleton of the Labrador duck there were
the usual fifteen cervical vertebræ and the usual nine dorsal vertebræ
bearing ribs; in the other skeleton there were fifteen cervical and ten
dorsal vertebræ with ribs; nor, as far as could be judged, was this
owing merely to a rib having been developed on the first lumbar
vertebra; for in both skeletons the lumbar vertebræ agreed perfectly in
number, shape, and size with those of the wild duck. In two skeletons
of the Call duck there were fifteen cervical and nine dorsal vertebræ;
in a third skeleton small ribs were attached to the so-called fifteenth
cervical vertebra, making ten pairs of ribs; but these ten ribs do not
correspond, or arise from the same vertebra, with the ten in the
above-mentioned Labrador duck. In the Call duck, which had small ribs
attached to the fifteenth cervical vertebra, the hæmal spines of the
thirteenth and fourteenth (cervical) and of the seventeenth (dorsal)
vertebræ corresponded with the spines on the fourteenth, fifteenth, and
eighteenth vertebræ of the wild duck: so that each of these vertebræ
had acquired a structure proper to one posterior to it in position. In
the eighth cervical vertebra of this same Call duck (fig. 40, B), the
two branches of the hæmal spine stand much closer together than in the
wild duck (A), and the descending hæmal processes are much shortened.
In the Penguin duck the neck from its thinness and erectness falsely
appears (as ascertained by measurement) to be much elongated, but the
cervical and dorsal vertebræ present no difference; the posterior
dorsal vertebræ, however, are more completely anchylosed to the pelvis
than in the wild duck. The Aylesbury duck has fifteen cervical and ten
dorsal vertebræ furnished with ribs, but the same number of lumbar,
sacral, and caudal vertebræ, as far as could be traced, as in the wild
duck. The cervical vertebræ in this same duck (fig. 40, D) were much
broader and thicker relatively to their length than in the wild (C); so
much so, that I have thought it worth while to give a sketch of the
twelfth cervical vertebra in these two birds. From the foregoing
statements we see that the fifteenth cervical vertebra occasionally
becomes modified into a dorsal vertebra, and when this occurs all the
adjoining vertebræ are modified. We also see that an additional dorsal
vertebra bearing a rib is occasionally developed, the number of the
cervical and lumbar vertebræ apparently remaining the same as usual.
I examined the bony enlargement of the trachea in the males of the
Penguin, Call, Hook-billed, Labrador, and Aylesbury breeds; and in all
it was identical in shape.
The _pelvis_ is remarkably uniform; but in the skeleton of the
Hook-billed duck the anterior part is much bowed inwards; in the
Aylesbury and some other breeds the ischiadic foramen is less
elongated. In the sternum, furculum, coracoids, and scapulæ, the
differences are so slight and so variable as not to be worth notice,
except that in two skeletons of the Penguin duck the terminal portion
of the scapula was much attenuated.
In the bones of the leg and wing no modification in shape could be
observed. But in the Penguin and Hook-billed ducks, the terminal
phalanges of the wing are a little shortened. In the former, the femur,
and metatarsus (but not the tibia) are considerably lengthened,
relatively to the same bones in the wild duck, and to the wing-bones in
both birds. This elongation of the leg-bones could be seen whilst the
bird was alive, and is no doubt connected with its peculiar upright
manner of walking. In a large Aylesbury duck, on the other hand, the
tibia was the only bone of the leg which relatively to the other bones
was slightly lengthened.
_On the effects of the increased and decreased Use of the Limbs._—In
all the breeds the bones of the wing (measured separately after having
been cleaned) relatively to those of the leg have become slightly
shortened, in comparison with the same bones in the wild duck, as may
be seen in Table I.
Table I
Name of Breed Length of Femur,
Tibia, and Meta-
tarsus together Length of Humerus,
Radius, and Meta-
carpus together Or as Inches Inches Wild
mallard 7·14 9·28 100 : 129
Aylesbury 8·64 10·43 100 : 120 Tufted
(Dutch) 8·25 9·83 100 : 119 Penguin 7·12
8·78 100 : 123 Call 6·20 7·77 100 : 125 Length
of same
Bones Length of all the
Bones of Wing Inches Inches Wild duck (another
specimen) 6·85 10·07 100 : 147 Common domestic
duck 8·15 11·26 100 : 138
In Table I we see, by comparison with the wild duck, that the reduction
in the length of the bones of the wing, relatively to those of the
legs, though slight, is universal. The reduction is least in the Call
duck, which has the power and the habit of frequently flying.
In weight there is a greater relative difference between the bones of
the leg and wing, as may be seen in Table II:—
Table II
Name of Breed Weight of Femur,
Tibia, and
Metatarsus Weight of
Humerus, Radius,
and Metacarpus Or as Grains Grains Wild mallard
54 97 100 : 179 Aylesbury 164 204 100 : 124
Hooked-bill 107 160 100 : 149 Tufted
(Dutch) 111 148 100 : 133 Penguin 75
90.5 100 : 120 Labrador 141 165 100 : 117
Call 57 93 100 : 163 Weight of all the
Bones of the
Leg and Foot Weight of all the
Bones of the
Wing Grains Grains Wild (another specimen)
66 115 100 : 173 Common domestic
duck 127 158 100 : 124
In these domesticated birds, the considerably lessened weight of the
bones of the wing (_i.e._ on an average, twenty-five per cent of their
proper proportional weight), as well as their slightly lessened length,
relatively to the leg-bones, might follow, not from any actual decrease
in the wing-bones, but from the increased weight and length of the
bones of the legs. Table IIIa shows that the leg-bones relatively to
the weight of the entire skeleton have really increased in weight; but
Table IIIb shows that according to the same standard the wing-bones
have also really decreased in weight; so that the relative
disproportion shown in the foregoing tables between the wing and
leg-bones, in comparison with those of the wild duck, is partly due to
the increase in weight and length of the leg-bones, and partly to the
decrease in weight and length of the wing-bones.
Table III
Name of Breed Weight of entire
Skeleton.
(N.B. One Metatarsus
and Foot was
removed from each
skeleton, as it had
been accidentally lost
in two cases.) Weight of
Femur,
Tibia, and
Metatarsus Or as Grains Grains Wild mallard
839 54 1000 : 64 Aylesbury 1925 164 1000 :
85 Tufted (Dutch) 1404 111 1000 : 79 Penguin
871 75 1000 : 86 Call (from Mr. Fox) 717
57 1000 : 79 Weight of Skeleton
as above. Weight of
Humerus,
Radius and
Metacarpus. Grains Grains Wild mallard 839
97 1000 : 115 Aylesbury 1925 204 1000 : 105
Tufted (Dutch) 1404 148 1000 : 105 Penguin
871 90 1000 : 103 Call (from Mr. Baker)
914 100 1000 : 109 Call (from Mr. Fox) 717
92 1000 : 129
With respect to Table III, I may first state that I tested them by
taking another skeleton of a wild duck and of a common domestic duck,
and by comparing the weight of _ all_ the bones of the leg with _all_
those of the wings, and the result was the same. In the first of these
tables we see that the leg-bones in each case have increased in actual
weight. It might have been expected that, with the increased or
decreased weight of the entire skeleton, the leg-bones would have
become proportionally heavier or lighter; but their greater weight in
all the breeds relatively to the other bones can be accounted for only
by these domestic birds having used their legs in walking and standing
much more than the wild, for they never fly, and the more artificial
breeds rarely swim. In the second table we see, with the exception of
one case, a plain reduction in the weight of the bones of the wing, and
this no doubt has resulted from their lessened use. The one exceptional
case, namely, in one of the Call ducks, is in truth no exception, for
this bird was constantly in the habit of flying about; and I have seen
it day after day rise from my grounds, and fly for a long time in
circles of more than a mile in diameter. In this Call duck there is not
only no decrease, but an actual increase in the weight of the
wing-bones relatively to those of the wild-duck; and this probably is
consequent on the remarkable lightness and thinness of all the bones of
the skeleton.
Lastly, I weighed the furculum, coracoids, and scapula of a wild duck
and of a common domestic duck, and I found that their weight,
relatively to that of the whole skeleton, was as one hundred in the
former to eighty-nine in the latter; this shows that these bones in the
domestic duck have been reduced eleven per cent of their due
proportional weight. The prominence of the crest of the sternum,
relatively to its length, is also much reduced in all the domestic
breeds. These changes have evidently been caused by the lessened use of
the wings.
It is well known that several birds, belonging to different Orders, and
inhabiting oceanic islands, have their wings greatly reduced in size
and are incapable of flight. I suggested in my ‘Origin of Species’
that, as these birds are not persecuted by any enemies, the reduction
of their wings had probably been caused by gradual disuse. Hence,
during the earlier stages of the process of reduction, such birds would
probably have resembled our domesticated ducks in the state of their
organs of flight. This is the case with the water-hen (_Gallinula
nesiotis_) of Tristan d’Acunha, which “can flutter a little, but
obviously uses its legs, and not its wings, as a mode of escape.” Now
Mr. Sclater[19] finds in this bird that the wings, sternum, and
coracoids are all reduced in length, and the crest of the sternum in
depth, in comparison with the same bones in the European water-hen (_G.
chloropus_). On the other hand, the thigh-bones and pelvis are
increased in length, the former by four lines, relatively to the same
bones in the common water-hen. Hence in the skeleton of this natural
species nearly the same changes have occurred, only carried a little
further, as with our domestic ducks, and in this latter case I presume
no one will dispute that they have resulted from the lessened use of
the wings and the increased use of the legs.
THE GOOSE.
This bird deserves some notice, as hardly any other anciently
domesticated bird or quadruped has varied so little. That geese were
anciently domesticated we know from certain verses in Homer; and from
these birds having been kept (388 B.C.) in the Capitol at Rome as
sacred to Juno, which sacredness implies great antiquity.[20] That the
goose has varied in some degree, we may infer from naturalists not
being unanimous with respect to its wild parent-form; though the
difficulty is chiefly due to the existence of three or four closely
allied wild European species.[21] A large majority of capable judges
are convinced that our geese are descended from the wild Grey-leg goose
(_A. ferus_); the young of which can easily be tamed.[22] This species,
when crossed with the domestic goose, produced in the Zoological
Gardens, as I was assured in 1849, perfectly fertile offspring.[23]
Yarrell[24] has observed that the lower part of the trachea of the
domestic goose is sometimes flattened, and that a ring of white
feathers sometimes surrounds the base of the beak. These characters
seem at first sight good indications of a cross at some former period
with the white-fronted goose (_A. albifrons_); but the white ring is
variable in this latter species, and we must not overlook the law of
analogous variation; that is, of one species assuming some of the
characters of allied species.
As the goose has proved so little flexible in its organisation under
long-continued domestication, the amount of variation which it has
undergone may be worth giving. It has increased in size and in
productiveness;[25] and varies from white to a dusky colour. Several
observers[26] have stated that the gander is more frequently white than
the goose, and that when old it almost invariably becomes white; but
this is not the case with the parent-form, the _A. ferus._ Here, again,
the law of analogous variation may have come into play, as the almost
snow-white male of the Rock goose (_Bernicla antarctica_) standing on
the sea-shore by his dusky partner is a sight well known to those who
have traversed the sounds of Tierra del Fuego and the Falkland Islands.
Some geese have top-knots; and the skull beneath, as before stated, is
perforated. A sub-breed has lately been formed with the feathers
reversed at the back of the head and neck.[27] The beak varies a little
in size, and is of a yellower tint than in the wild species; but its
colour and that of the legs are both slightly variable.[28] This latter
fact deserves attention, because the colour of the legs and beak is
highly serviceable in discriminating the several closely allied wild
forms.[29] At our Shows two breeds are exhibited; viz., the Embden and
Toulouse; but they differ in nothing except colour.[30] Recently a
smaller and singular variety has been imported from Sebastopol,[31]
with the scapular feathers (as I hear from Mr. Tegetmeier, who sent me
specimens) greatly elongated, curled, and even spirally twisted. The
margins of these feathers are rendered plumose by the divergence of the
barbs and barbules, so that they resemble in some degree those on the
back of the black Australian swan. These feathers are likewise
remarkable from the central shaft, which is excessively thin and
transparent, being split into fine filaments, which, after running for
a space free, sometimes coalesce again. It is a curious fact that these
filaments are regularly clothed on each side with fine down or
barbules, precisely like those on the proper barbs of the feather. This
structure of the feathers is transmitted to half-bred birds. In _
Gallus sonneratii_ the barbs and barbules blend together, and form thin
horny plates of the same nature with the shaft: in this variety of the
goose, the shaft divides into filaments which acquire barbules, and
thus resemble true barbs.
Although the domestic goose certainly differs somewhat from any known
wild species, yet the amount of variation which it has undergone, as
compared with that of most domesticated animals, is singularly small.
This fact can be partially accounted for by selection not having come
largely into play. Birds of all kinds which present many distinct races
are valued as pets or ornaments; no one makes a pet of the goose; the
name, indeed, in more languages than one, is a term of reproach. The
goose is valued for its size and flavour, for the whiteness of its
feathers which adds to their value, and for its prolificness and
tameness. In all these points the goose differs from the wild
parent-form; and these are the points which have been selected. Even in
ancient times the Roman gourmands valued the liver of the _white_
goose; and Pierre Belon[32] in 1555 speaks of two varieties, one of
which was larger, more fecund, and of a better colour than the other;
and he expressly states that good managers attended to the colour of
their goslings, so that they might know which to preserve and select
for breeding.
THE PEACOCK.
This is another bird which has hardly varied under domestication,
except in sometimes being white or piebald. Mr. Waterhouse carefully
compared, as he informs me, skins of the wild Indian and domestic bird,
and they were identical in every respect, except that the plumage of
the latter was perhaps rather thicker. Whether our birds are descended
from those introduced into Europe in the time of Alexander, or have
been subsequently imported, is doubtful. They do not breed very freely
with us, and are seldom kept in large numbers,—circumstances which
would greatly interfere with the gradual selection and formation of new
breeds. There is one strange fact with respect to the peacock, namely,
the occasional appearance in England of the “japanned” or
“black-shouldered” kind. This form has lately been named on the high
authority of Mr. Sclater as a distinct species, viz. _Pavo
nigripennis,_ which he believes will hereafter be found wild in some
country, but not in India, where it is certainly unknown. The males of
these japanned birds differ conspicuously from the common peacock in
the colour of their secondary wing-feathers, scapulars, wing-coverts,
and thighs, and are I think more beautiful; they are rather smaller
than the common sort, and are always beaten by them in their battles,
as I hear from the Hon. A. S. G. Canning. The females are much paler
coloured than those of the common kind. Both sexes, as Mr. Canning
informs me, are white when they leave the egg, and they differ from the
young of the white variety only in having a peculiar pinkish tinge on
their wings. These japanned birds, though appearing suddenly in flocks
of the common kind, propagate their kind quite truly. Although they do
not resemble the hybrids which have been raised between _P. cristatus_
and _ muticus,_ nevertheless they are in some respects intermediate in
character between these two species; and this fact favours, as Mr.
Sclater believes, the view that they form a distinct and natural
species.[33]
On the other hand, Sir H. Heron states[34] that this breed suddenly
appeared within his memory in Lord Brownlow’s large stock of pied,
white, and common peacocks. The same thing occurred in Sir J.
Trevelyan’s flock composed entirely of the common kind, and in Mr.
Thornton’s stock of common and pied peacocks. It is remarkable that in
these two latter instances the black-shouldered kind, though a smaller
and weaker bird, increased, “to the extinction of the previously
existing breed.” I have also received through Mr. Sclater a statement
from Mr. Hudson Gurney that he reared many years ago a pair of
black-shouldered peacocks from the common kind; and another
ornithologist, Prof. A. Newton, states that, five or six years ago, a
female bird, in all respects similar to the female of the
black-shouldered kind, was produced from a stock of common peacocks in
his possession, which during more than twenty years had not been
crossed with birds of any other strain. Mr. Jenner Weir informs me that
a peacock at Blackheath whilst young was white, but as it became older
gradually assumed the characters of the black-shouldered variety; both
its parents were common peacocks. Lastly, Mr. Canning has given a case
of a female of this same variety appearing in Ireland in a flock of the
ordinary kind.[35] Here, then, we have seven well authenticated cases
in Great Britain of japanned birds, having suddenly appeared within
recent times in flocks of the common peafowl. This variety must also
have formerly appeared in Europe, for Mr. Canning has seen an old
picture, and another is referred to in the ‘Field,’ with this variety
represented. These facts seem to me to indicate that the japanned
peacock is a strongly marked variety or “sport,” which tends at all
times and in many places to reappear. This view is supported by the
young being at first white like the young of the white breed, which is
undoubtedly a variation. If, on the other hand, we believe the japanned
peacock to be a distinct species, we must suppose that in all the above
cases the common breed had at some former period been crossed by it,
but had lost every trace of the cross; yet that the offspring of these
birds suddenly and completely reacquired through reversion the
characters of _P. nigripennis._ I have heard of no other such case in
the animal or vegetable kingdom. To perceive the full improbability of
such an occurrence, we may suppose that a breed of dogs had been
crossed at some former period with a wolf, but had lost every trace of
the wolf-like character, yet that the breed gave birth in seven
instances in the same country, within no great length of time, to a
wolf perfect in every character; and we must further suppose that in
two of the cases, the newly produced wolves afterwards spontaneously
increased to such an extent as to lead to the extinction of the parent
breed of dogs. So remarkable a bird as the _P. nigripennis,_ when first
imported, would have realised a large price; it is therefore improbable
that it should have been silently introduced and its history
subsequently lost. On the whole the evidence seems to me, as it did to
Sir R. Heron, to be decisive in favour of the japanned or
black-shouldered breed being a variation, induced by some unknown
cause. On this view, the case is the most remarkable one ever recorded
of the abrupt appearance of a new form, which so closely resembles a
true species that it has deceived one of the most experienced of living
ornithologists.
THE TURKEY.
It seems fairly well established by Mr. Gould,[36] that the turkey, in
accordance with the history of its first introduction, is descended
from a wild Mexican form, which had been domesticated by the natives
before the discovery of America, and which is now generally ranked as a
local race, and not as a distinct species. However this may be, the
case deserves notice because in the United States wild male turkeys
sometimes court the domestic hens, which are descended from the Mexican
form, “and are generally received by them with great pleasure.”[37]
Several accounts have likewise been published of young birds, reared in
the United States from the eggs of the wild species, crossing and
commingling with the common breed. In England, also, this same species
has been kept in several parks; from two of which the Rev. W. D. Fox
procured birds, and they crossed freely with the common domestic kind,
and during many years afterwards, as he informs me, the turkeys in his
neighbourhood clearly showed traces of their crossed parentage. We here
have an instance of a domestic race being modified by a cross with a
distinct wild race or species. F. Michaux[38] suspected in 1802 that
the common domestic turkey was not descended from the United States
species alone, but likewise from a southern form, and he went so far as
to believe that English and French turkeys differed from having
different proportions of the blood of the two parent-forms.
English turkeys are smaller than either wild form. They have not varied
in any great degree; but there are some breeds which can be
distinguished as Norfolks, Suffolks, Whites, and Copper-coloured (or
Cambridge), all of which, if precluded from crossing with other breeds
propagate their kind truly. Of these kinds, the most distinct is the
small, hardy, dull-black Norfolk turkey, of which the chickens are
black, occasionally with white patches about the head. The other breeds
scarcely differ except in colour, and their chickens are generally
mottled all over with brownish-grey.[39] The inferior tail-coverts vary
in number, and according to a German superstition the hen lays as many
eggs as the cock has feathers of this kind.[40] Albin in 1738, and
Temminck within a much later period, describe a beautiful breed,
dusky-yellowish, brown above and white beneath, with a large top-knot
of soft plumose feather. The spurs of the male were rudimentary. This
breed has been for a long time extinct in Europe; but a living specimen
has lately been imported from the east coast of Africa, which still
retains the top-knot and the same general colouring and rudimentary
spurs.[41] Mr. Wilmot has described[42] a white turkey-cock having a
crest formed of “feathers about four inches long, with bare quills, and
a tuft of soft white down growing at the end.” Many of the young birds
inherited this kind of crest, but afterwards it fell off or was pecked
out by the other birds. This is an interesting case, as with care a new
breed might probably have been formed; and a top-knot of this nature
would have been to a certain extent analogous to that borne by the
males in several allied genera, such as Euplocomus, Lophophorus, and
Pavo.
Wild turkeys, believed in every instance to have been imported from the
United States, have been kept in the parks of Lords Powis, Leicester,
Hill, and Derby. The Rev. W. D. Fox procured birds from the two
first-named parks, and he informs me that they certainly differed a
little from each other in the shape of their bodies and in the barred
plumage on their wings. These birds likewise differed from Lord Hill’s
stock. Some of the latter kept at Oulton by Sir P. Egerton, though
precluded from crossing with common turkeys, occasionally produced much
paler-coloured birds, and one that was almost white, but not an albino.
These half-wild turkeys, in thus differing slightly from each other,
present an analogous case with the wild cattle kept in the several
British parks. We must suppose that such differences have resulted from
the prevention of free intercrossing between birds ranging over a wide
area, and from the changed conditions to which they have been exposed
in England. In India the climate has apparently wrought a still greater
change in the turkey, for it is described by Mr. Blyth[43] as being
much degenerated in size, “utterly incapable of rising on the wing,” of
a black colour, and “with the long pendulous appendages over the beak
enormously developed.”
THE GUINEA FOWL.
The domesticated Guinea fowl is now believed by some naturalists to be
descended from the _Numida ptilorhynca,_ which inhabits very hot, and,
in parts, extremely arid districts in Eastern Africa; consequently it
has been exposed in this country to extremely different conditions of
life. Nevertheless it has hardly varied at all, except in the plumage
being either paler or darker-coloured. It is a singular fact that this
bird varies more in colour in the West Indies and on the Spanish Main,
under a hot though humid climate, than in Europe.[44] The Guinea fowl
has become thoroughly feral in Jamaica and in St. Domingo,[45] and has
diminished in size; the legs are black, whereas the legs of the
aboriginal African bird are said to be grey. This small change is worth
notice on account of the often-repeated statement that all feral
animals invariably revert in every character to their original type.
THE CANARY BIRD.
As this bird has been recently domesticated, namely, within the last
350 years, its variability deserves notice. It has been crossed with
nine or ten other species of Fringillidæ, and some of the hybrids are
almost completely fertile; but we have no evidence that any distinct
breed has originated from such crosses. Notwithstanding the modern
domestication of the canary, many varieties have been produced; even
before the year 1718 a list of twenty-seven varieties was published in
France,[46] and in 1779 a long schedule of the desired qualities was
printed by the London Canary Society, so that methodical selection has
been practised during a considerable period. The greater number of the
varieties differ only in colour and in the markings of their plumage.
Some breeds however, differ in shape, such as the hooped or bowed
canaries, and the Belgian canaries with their much elongated bodies.
Mr. Brent[47] measured one of the latter and found it eight inches in
length, whilst the wild canary is only five and a quarter inches long.
There are top-knotted canaries, and it is a singular fact that, if two
top-knotted birds are matched, the young, instead of having very fine
top-knots, are generally bald, or even have a wound on their heads.[48]
It would appear as if the top-knot were due to some morbid condition,
which is increased to an injurious degree when two birds in this state
are paired. There is a feather-footed breed, and another with a kind of
frill running down the breast. One other character deserves notice from
being confined to one period of life, and from being strictly inherited
at the same period; namely, the wing and tail feathers in prize
canaries being black, “but this colour is retained only until the first
moult; once moulted, the peculiarity ceases.”[49] Canaries differ much
in disposition and character, and in some small degree in song. They
produce eggs three or four times during the year.
GOLD-FISH.
Besides mammals and birds, only a few animals belonging to the other
great classes have been domesticated; but to show that it is an almost
universal law that animals, when removed from their natural conditions
of life, vary, and that races can be formed when selection is applied,
it is necessary to say a few words on gold-fish, bees, and silk-moths.
Gold-fish (_Cyprinus auratus_) were introduced into Europe only two or
three centuries ago; but they have been kept in confinement from an
ancient period in China. Mr. Blyth[50] suspects, from the analogous
variation of other fishes, that golden-coloured fish do not occur in a
state of nature. These fishes frequently live under the most unnatural
conditions, and their variability in colour, size, and in some
important points of structure is very great. M. Sauvigny has described
and given coloured drawings of no less than eighty-nine varieties.[51]
Many of the varieties, however, such as triple tail-fins, etc., ought
to be called monstrosities; but it is difficult to draw any distinct
line between a variation and a monstrosity. As gold-fish are kept for
ornament or curiosity, and as “the Chinese are just the people to have
secluded a chance variety of any kind, and to have matched and paired
from it,”[52] it might have been predicted that selection would have
been largely practised in the formation of new breeds; and this is the
case. In an old Chinese work it is said that fish with vermilion scales
were first raised in confinement during the Sung dynasty (which
commenced A.D. 960), “and now they are cultivated in families
everywhere for the sake of ornament.” In another and more ancient work,
it is said that “there is not a household where the gold-fish is not
cultivated, in _rivalry_ as to its colour, and as a source of profit,”
etc.[53] Although many breeds exist, it is a singular fact that the
variations are often not inherited. Sir R. Heron[54] kept many of these
fishes, and placed all the deformed ones, namely, those destitute of
dorsal fins and those furnished with a double anal fin, or triple tail,
in a pond by themselves; but they did “not produce a greater proportion
of deformed offspring than the perfect fishes.”
Passing over an almost infinite diversity of colour, we meet with the
most extraordinary modifications of structure. Thus, out of about two
dozen specimens bought in London, Mr. Yarrell observed some with the
dorsal fin extending along more than half the length of the back:
others with this fin reduced to only five or six rays: and one with no
dorsal fin. The anal fins are sometimes double, and the tail is often
triple. This latter deviation of structure seems generally to occur “at
the expense of the whole or part of some other fin;”[55] but Bory de
Saint-Vincent[56] saw at Madrid gold-fish furnished with a dorsal fin
and a triple tail. One variety is characterised by a hump on its back
near the head; and the Rev. L. Jenyns[57] has described a most singular
variety, imported from China, almost globular in form like a Diodon,
with “the fleshy part of the tail as if entirely cut away? the caudal
fin being set on a little behind the dorsal and immediately above the
anal.” In this fish the anal and caudal fins were double; the anal fin
being attached to the body in a vertical line: the eyes also were
enormously large and protuberant.
HIVE-BEES.
Bees have been domesticated from an ancient period; if indeed their
state can be considered one of domestication, for they search for their
own food, with the exception of a little generally given to them during
the winter. Their habitation is a hive instead of a hole in a tree.
Bees, however, have been transported into almost every quarter of the
world, so that climate ought to have produced whatever direct effect it
is capable of producing. It is frequently asserted that the bees in
different parts of Great Britain differ in size, colour, and temper;
and Godron[58] says that they are generally larger in the south than in
other parts of France; it has also been asserted that the little brown
bees of High Burgundy, when transported to La Bresse become large and
yellow in the second generation. But these statements require
confirmation. As far as size is concerned, it is known that bees
produced in very old combs are smaller, owing to the cells having
become smaller from the successive old cocoons. The best
authorities[59] concur that, with the exception of the Ligurian race or
species, presently to be mentioned, distinct breeds do not exist in
Britain or on the Continent. There is, however, even in the same stock,
some variability in colour. Thus, Mr. Woodbury states,[60] that he has
several times seen queen bees of the common kind annulated with
yellow-like Ligurian queens, and the latter dark-coloured like common
bees. He has also observed variations in the colour of the drones,
without any corresponding difference in the queens or workers of the
same hive. The great apiarian, Dzierzon, in answer to my queries on
this subject, says,[61] that in Germany bees of some stocks are
decidedly dark, whilst others are remarkable for their yellow colour.
Bees also seem to differ in habits in different districts, for Dzierzon
adds, “If many stocks with their offspring are more inclined to swarm,
whilst others are richer in honey, so that some bee-keepers even
distinguish between swarming and honey-gathering bees, this is a habit
which has become second nature, caused by the customary mode of keeping
the bees and the pasturage of the district. For example, what a
difference in this respect one may perceive to exist between the bees
of the Luneburg heath and those of this country!” . . . “Removing an
old queen and substituting a young one of the current year is here an
infallible mode of keeping the strongest stock from swarming and
preventing drone-breeding; whilst the same means if adopted in Hanover
would certainly be of no avail.” I procured a hive full of dead bees
from Jamaica, where they have long been naturalised, and, on carefully
comparing them under the microscope with my own bees, I could detect
not a trace of difference.
This remarkable uniformity in the hive-bee, wherever kept, may probably
be accounted for by the great difficulty, or rather impossibility, of
bringing selection into play by pairing particular queens and drones,
for these insects unite only during flight. Nor is there any record,
with a single partial exception, of any person having separated and
bred from a hive in which the workers presented some appreciable
difference. In order to form a new breed, seclusion from other bees
would, as we now know, be indispensable; for since the introduction of
the Ligurian bee into Germany and England, it has been found that the
drones wander at least two miles from their own hives, and often cross
with the queens of the common bee.[62] The Ligurian bee, although
perfectly fertile when crossed with the common kind, is ranked by most
naturalists as a distinct species, whilst by others it is ranked as a
variety: but this form need not here be noticed, as there is no reason
to believe that it is the product of domestication. The Egyptian and
some other bees are likewise ranked by Dr. Gerstäcker,[63] but not by
other highly competent judges, as geographical races; he grounds his
conclusion in chief part on the fact that in certain districts, as in
the Crimea and Rhodes, they vary so much in colour, that the several
geographical races can be closely connected by intermediate forms.
I have alluded to a single instance of the separation and preservation
of a particular stock of bees. Mr. Lowe[64] procured some bees from a
cottager a few miles from Edinburgh, and perceived that they differed
from the common bee in the hairs on the head and thorax being lighter
coloured and more profuse in quantity. From the date of the
introduction of the Ligurian bee into Great Britain we may feel sure
that these bees had not been crossed with this form. Mr. Lowe
propagated this variety, but unfortunately did not separate the stock
from his other bees, and after three generations the new character was
almost completely lost. Nevertheless, as he adds, “a great number of
the bees still retain traces, though faint, of the original colony.”
This case shows us what could probably be effected by careful and
long-continued selection applied exclusively to the workers, for, as we
have seen, queens and drones cannot be selected and paired.
SILK-MOTHS.
These insects are in several respects interesting to us, more
especially because they have varied largely at an early period of life,
and the variations have been inherited at corresponding periods. As the
value of the silk-moth depends entirely on the cocoon, every change in
its structure and qualities has been carefully attended to, and races
differing much in the cocoon, but hardly at all in the adult state,
have been produced. With the races of most other domestic animals, the
young resemble each other closely, whilst the adults differ much.
It would be useless, even if it were possible, to describe all the many
kinds of silkworms. Several distinct species exist in India and China
which produce useful silk, and some of these are capable of freely
crossing with the common silk-moth, as has been recently ascertained in
France. Captain Hutton[65] states that throughout the world at least
six species have been domesticated; and he believes that the silk-moths
reared in Europe belong to two or three species. This, however, is not
the opinion of several capable judges who have particularly attended to
the cultivation of this insect in France; and hardly accords with some
facts presently to be given.
The common silk-moth (_Bombyx mori_) was brought to Constantinople in
the sixth century, whence it was carried into Italy, and in 1494 into
France.[66] Everything has been favourable for the variation of this
insect. It is believed to have been domesticated in China as long ago
as 2700 B.C. It has been kept under unnatural and diversified
conditions of life, and has been transported into many countries. There
is reason to believe that the nature of the food given to the
caterpillar influences to a certain extent the character of the
breed.[67] Disuse has apparently aided in checking the development of
the wings. But the most important element in the production of the many
now existing, much modified races, no doubt has been the close
attention which has long been applied in many countries to every
promising variation. The care taken in Europe in the selection of the
best cocoons and moths for breeding is notorious,[68] and the
production of eggs is followed as a distinct trade in parts of France.
I have made inquiries through Dr. Falconer, and am assured that in
India the natives are equally careful in the process of selection. In
China the production of eggs is confined to certain favourable
districts, and the raisers are precluded by law from producing silk, so
that their whole attention may be necessarily given up to this one
object.[69]
The following details on the differences between the several breeds are
taken, when not stated to the contrary, from M. Robinet’s excellent
work,[70] which bears every sign of care and large experience. The
_eggs_ in the different races vary in colour, in shape (being round,
elliptic or oval), and in size. The eggs laid in June in the south of
France, and in July in the central provinces, do not hatch until the
following spring; and it is in vain, says M. Robinet, to expose them to
a temperature gradually raised, in order that the caterpillar may be
quickly developed. Yet occasionally, without any known cause, batches
of eggs are produced, which immediately begin to undergo the proper
changes, and are hatched in from twenty to thirty days. From these and
some other analogous facts it may be concluded that the Trevoltini
silkworms of Italy, of which the caterpillars are hatched in from
fifteen to twenty days, do not necessarily form, as has been
maintained, a distinct species. Although the breeds which live in
temperate countries produce eggs which cannot be immediately hatched by
artificial heat, yet when they are removed to and reared in a hot
country they gradually acquire the character of quick development, as
in the Trevoltini races.[71]
_Caterpillars._—These vary greatly in size and colour. The skin is
generally white, sometimes mottled with black or grey, and occasionally
quite black. The colour, however, as M. Robinet asserts, is not
constant, even in perfectly pure breeds; except in the race _tigrée,_
so called from being marked with transverse black stripes. As the
general colour of the caterpillar is not correlated with that of the
silk,[72] this character is disregarded by cultivators, and has not
been fixed by selection. Captain Hutton, in the paper before referred
to, has argued with much force that the dark tiger-like marks, which so
frequently appear during the later moults in the caterpillars of
various breeds, are due to reversion; for the caterpillars of several
allied wild species of Bombyx are marked and coloured in this manner.
He separated some caterpillars with the tiger-like marks, and in the
succeeding spring (pp. 149, 298) nearly all the caterpillars reared
from them were dark-brindled, and the tints became still darker in the
third generation. The moths reared from these caterpillars[73] also
became darker, and resembled in colouring the wild _B. huttoni._ On
this view of the tiger-like marks being due to reversion, the
persistency with which they are transmitted is intelligible.
Several years ago Mrs. Whitby took great pains in breeding silkworms on
a large scale, and she informed me that some of her caterpillars had
dark eyebrows. This is probably the first step in reversion towards the
tiger-like marks, and I was curious to know whether so trifling a
character would be inherited. At my request she separated in 1848
twenty of these caterpillars, and having kept the moths separate, bred
from them. Of the many caterpillars thus reared, “every one without
exception had eyebrows, some darker and more decidedly marked than the
others, but _all_ had eyebrows more or less plainly visible.” Black
caterpillars occasionally appear amongst those of the common kind, but
in so variable a manner, that, according to M. Robinet, the same race
will one year exclusively produce white caterpillars, and the next year
many black ones; nevertheless, I have been informed by M. A. Bossi of
Geneva, that, if these black caterpillars are separately bred from,
they reproduce the same colour; but the cocoons and moths reared from
them do not present any difference.
The caterpillar in Europe ordinarily moults four times before passing
into the cocoon stage; but there are races “à trois mues,” and the
Trevoltini race likewise moults only thrice. It might have been thought
that so important a physiological difference would not have arisen
under domestication; but M. Robinet[74] states that, on the one hand,
ordinary caterpillars occasionally spin their cocoons after only three
moults, and, on the other hand, “presque toutes les races à trois mues,
que nous avons expérimentees, ont fait quatre mues à la seconde ou à la
troisième année, ce qui semble prouver qu’il a suffi de les placer dans
des conditions favorables pour leur rendre une faculté qu’elles avaient
perdue sous des influences moins favorables.”
_Cocoons._—The caterpillar in changing into the cocoon loses about 50
per cent of its weight; but the amount of loss differs in different
breeds, and this is of importance to the cultivator. The cocoon in the
different races presents characteristic differences; being large or
small;—nearly spherical with no constriction, as in the Race de Loriol,
or cylindrical, with either a deep or slight constriction in the
middle; with the two ends, or with one end alone, more or less pointed.
The silk varies in fineness and quality, and in being nearly white, but
of two tints, or yellow. Generally the colour of the silk is not
strictly inherited: but in the chapter on Selection I shall give a
curious account how, in the course of sixty-five generations, the
number of yellow cocoons in one breed has been reduced in France from
one hundred to thirty-five in the thousand. According to Robinet, the
white race, called Sina, by careful selection during the last
seventy-five years, “est arrivée à un tel état de pureté, qu’on ne voit
pas un seul cocon jaune dans des millions de cocons blancs.”[75]
Cocoons are sometimes formed, as is well known, entirely destitute of
silk, which yet produce moths; unfortunately Mrs. Whitby was prevented
by an accident from ascertaining whether this character would prove
hereditary.
_Adult stage._—I can find no account of any constant difference in the
moths of the most distinct races. Mrs. Whitby assured me that there was
none in the several kinds bred by her; and I have received a similar
statement from the eminent naturalist, M. de Quatrefages. Captain
Hutton also says[76] that the moths of all kinds vary much in colour,
but in nearly the same inconstant manner. Considering how much the
cocoons in the several races differ, this fact is of interest, and may
probably be accounted for on the same principle as the fluctuating
variability of colour in the caterpillar, namely, that there has been
no motive for selecting and perpetuating any particular variation.
The males of the wild Bombycidæ “fly swiftly in the day-time and
evening, but the females are usually very sluggish and inactive.”[77]
In several moths of this family the females have abortive wings, but no
instance is known of the males being incapable of flight, for in this
case the species could hardly have been perpetuated. In the silk-moth
both sexes have imperfect, crumpled wings, and are incapable of flight;
but still there is a trace of the characteristic difference in the two
sexes; for though, on comparing a number of males and females, I could
detect no difference in the development of their wings, yet I was
assured by Mrs. Whitby that the males of the moths bred by her used
their wings more than the females, and could flutter downwards, though
never upwards. She also states that, when the females first emerge from
the cocoon, their wings are less expanded than those of the male. The
degree of imperfection, however, in the wings varies much in different
races and under different circumstances. M. Quatrefages[78] says that
he has seen a number of moths with their wings reduced to a third,
fourth, or tenth part of their normal dimensions, and even to mere
short straight stumps: “il me semble qu’il y a là un véritable arrêt de
développement partiel.” On the other hand, he describes the female
moths of the André Jean breed as having “leurs ailes larges et étalées.
Un seul présente quelques courbures irrégulières et des plis anormaux.”
As moths and butterflies of all kinds reared from wild caterpillars
under confinement often have crippled wings, the same cause, whatever
it may be, has probably acted on silk-moths, but the disuse of their
wings during so many generations has, it may be suspected, likewise
come into play.
The moths of many breeds fail to glue their eggs to the surface on
which they are laid,[79] but this proceeds, according to Capt.
Hutton,[80] merely from the glands of the ovipositor being weakened.
As with other long-domesticated animals, the instincts of the silk-moth
have suffered. The caterpillars, when placed on a mulberry-tree, often
commit the strange mistake of devouring the base of the leaf on which
they are feeding, and consequently fall down; but they are capable,
according to M. Robinet,[81] of again crawling up the trunk. Even this
capacity sometimes fails, for M. Martins[82] placed some caterpillars
on a tree, and those which fell were not able to remount and perished
of hunger; they were even incapable of passing from leaf to leaf.
Some of the modifications which the silk-moth has undergone stand in
correlation with one another. Thus, the eggs of the moths which produce
white cocoons and of those which produce yellow cocoons differ slightly
in tint. The abdominal feet, also, of the caterpillars which yield
white cocoons are always white, whilst those which give yellow cocoons
are invariably yellow.[83] We have seen that the caterpillars with dark
tiger-like stripes produce moths which are more darkly shaded than
other moths. It seems well established[84] that in France the
caterpillars of the races which produce white silk, and certain black
caterpillars, have resisted, better than other races, the disease which
has recently devastated the silk-districts. Lastly, the races differ
constitutionally, for some do not succeed so well under a temperate
climate as others; and a damp soil does not equally injure all the
races.[85]
From these various facts we learn that silk-moths, like the higher
animals, vary greatly under long-continued domestication. We learn also
the more important fact that variations may occur at various periods of
life, and be inherited at a corresponding period. And finally we see
that insects are amenable to the great principle of Selection.
REFERENCES
[1] ‘Poultry Chronicle,’ 1854, vol. ii. p. 91 and vol. i. p. 330.
[2] Dr. Turral, ‘Bull. Soc. d’Acclimat.,’ tom. vii., 1860, p. 541.
[3] Willughby’s ‘Ornithology,’ by Ray, p. 381. This breed is also
figured by Albin in 1734 in his ‘Nat. Hist. of Birds,’ vol. ii. p. 86.
[4] F. Cuvier, in ‘Annales du Muséum,’ tom. ix. p. 128, says that
moulting and incubation alone stops these ducks laying. Mr. B. P.
Brent makes a similar remark in the ‘Poultry Chronicle,’ 1855, vol.
iii. p. 512.
[5] Rev. E. S. Dixon, ‘Ornamental and Domestic Poultry’ (1848), p.
117. Mr. B. P. Brent, in ‘Poultry Chronicle,’ vol. iii., 1855, p. 512.
[6] Crawfurd on the ‘Relation of Domesticated Animals to
Civilisation,’ read before the Brit. Assoc. at Oxford, 1860.
[7] Dureau de La Malle, in ‘Annales des Sciences Nat.,’ tom. xvii. p.
164; and tom. xxi. p. 55. Rev. E. S. Dixon, ‘Ornamental Poultry,’ p.
118. Tame ducks were not known in Aristotle’s time, as remarked by
Volz, in his ‘Beiträge zur Kulturgeschichte,’ 1852, s. 78.
[8] I quote this account from ‘Die Enten-und Schwanenzucht,’ Ulm 1828,
s. 143. _See_ Audubon’s ‘Ornithological Biography,’ vol. iii. p. 168,
on the taming of ducks on the Mississippi. For the same fact in
England, _see_ Mr. Waterton in Loudon’s ‘Mag. of Nat. Hist.,’ vol.
viii. 1835, p. 542; and Mr. St. John, ‘Wild Sports and Nat. Hist. of
the Highlands,’ 1846, p. 129.
[9] Mr. E. Hewitt, in ‘Journal of Horticulture,’ 1862, p. 773; and
1863, p. 39.
[10] I have met with several statements on the fertility of the
several breeds when crossed. Mr. Yarrell assured me that Call and
common ducks are perfectly fertile together. I crossed Hook-billed and
common ducks, and a Penguin and Labrador, and the crossed Ducks were
quite fertile, though they were not bred _ inter se,_ so that the
experiment was not fully tried. Some half-bred Penguins and Labradors
were again crossed with Penguins, and subsequently bred by me _inter
se,_ and they were extremely fertile.
[11] ‘Poultry Chronicle,’ 1855, vol. iii. p. 512.
[12] ‘Journal of the Indian Archipelago,’ vol. v. p. 334.
[13] ‘The Zoologist,’ vols. vii, viii. (1849-1850), p. 2353.
[14] ‘Poultry Chronicle,’ 1855, vol. iii. p. 512.
[15] ‘Poultry Chronicle,’ vol. iii. 1855, p. 312. With respect to
Rouens _see_ ditto vol. i. 1854, p. 167.
[16] Col. Hawker’s ‘Instructions to young Sportsmen,’ quoted by Mr.
Dixon in his ‘Ornamental Poultry,’ p. 125.
[17] ‘Cottage Gardener,’ April 9th, 1861.
[18] These hybrids have been described by M. Selys-Longchamps in the
‘Bulletins (tom. xii. No 10) Acad. Roy. de Bruxelles.’
[19] ‘Proc. Zoolog. Soc.,’ 1861, p. 261.
[20] ‘Ceylon,’ by Sir J. E. Tennent, 1859, vol. i. p. 485; also J.
Crawfurd on the ‘Relation of Domest. Animals to Civilisation,’ read
before Brit. Assoc. 1860. _See also_ ‘Ornamental Poultry,’ by Rev. E.
S. Dixon, 1848, p. 132. The goose figured on the Egyptian monuments
seems to have been the Red goose of Egypt.
[21] Macgillivray’s ‘British Birds,’ vol. iv. p. 593.
[22] Mr. A. Strickland (‘Annals and Mag. of Nat. Hist.,’ 3rd series,
vol. iii. 1859, p. 122) reared some young wild geese, and found them
in habits and in all characters identical with the domestic goose.
[23] _See also_ Hunter’s ‘Essays,’ edited by Owen, vol. ii. p. 322.
[24] Yarrell’s ‘British Birds,’ vol. iii. p. 142.
[25] L. Lloyd, ‘Scandinavian Adventures,’ 1854, vol. ii. p. 413, says
that the wild goose lays from five to eight eggs, which is a much
fewer number than that laid by our domestic goose.
[26] The Rev. L. Jenyns (Blomefield) seems first to have made this
observation in his ‘British Animals.’ _See also_ Yarrell, and Dixon in
his ‘Ornamental Poultry’ (p. 139), and ‘Gardener’s Chronicle,’ 1857,
p. 45.
[27] Mr. Bartlet exhibited the head and neck of a bird thus
characterised before the Zoological Soc., Feb. 1860.
[28] W. Thompson, ‘Natural Hist. of Ireland,’ 1851, vol. iii. p. 31.
The Rev. E. S. Dixon gave me some information on the varying colour of
the beak and legs.
[29] Mr. A. Strickland, in ‘Annals and Mag. of Nat. Hist.,’ 3rd
series, vol. iii., 1859, p. 122.
[30] ‘Poultry Chronicle,’ vol. i., 1854, p. 498; vol. iii. p. 210.
[31] ‘The Cottage Gardener.’ Sept. 4th, 1860, p. 348.
[32] ‘L’Hist. de la Nature des Oiseaux,’ par P. Belon, 1555, p. 156.
With respect to the livers of white geese being preferred by the
Romans _see_ Isid. Geoffroy St.-Hilaire ‘Hist. Nat. Gén.,’ tom. iii.
p. 58.
[33] Mr. Sclater on the black-shouldered peacock of Latham, ‘Proc.
Zoolog. Soc.,’ April 24th, 1860. Mr. Swinhoe at one time believed,
(‘Ibis,’ July, 1868) that this kind of peafowl was found wild in
Cochin China, but he has since informed me that he feels very doubtful
on this head.
[34] ‘Proc. Zoolog. Soc.,’ April 14th, 1835.
[35] ‘The Field,’ May 6th, 1871. I am much indebted to Mr. Canning for
information with respect to his birds.
[36] ‘Proc. Zoolog. Soc.,’ April 8th, 1856, p. 61. Prof. Baird
believes (as quoted in Tegetmeier’s ‘Poultry Book,’ 1866, p. 269) that
our turkeys are descended from a West Indian species now extinct. But
besides the improbability of a bird having long ago become extinct in
these large and luxuriant islands, it appears (as we shall presently
see) that the turkey degenerates in India, and this fact indicates
that it was not aboriginally an inhabitant of the lowlands of the
tropics.
[37] Audubon’s ‘Ornithological Biography,’ vol. i., 1831, pp. 4-13;
and ‘Naturalist’s Library,’ vol. xiv., Birds, p. 138.
[38] F. Michaux, ‘Travels in N. America,’ 1802, Eng. translat., p.
217.
[39] ‘Ornamental Poetry,’ by the Rev. E. S. Dixon, 1848, p. 34.
[40] Bechstein, ‘Naturgesch. Deutschlands,’ B. iii., 1793, s. 309.
[41] Mr. Bartlett in ‘Land and Water,’ Oct. 31st, 1868, p. 233; and
Mr. Tegetmeier in the ‘Field,’ July 17th, 1869, p. 46.
[42] ‘Gardener’s Chronicle,’ 1852, p. 699.
[43] E. Blyth, in ‘Annals and Mag. of Nat. Hist.,’ 1847, vol. xx. p.
391.
[44] Roulin makes this remark in ‘Mém. de divers Savans, l’Acad. des
Sciences,’ tom. vi., 1835, p. 349. Mr. Hill, of Spanish Town, in a
letter to me, describes five varieties of the Guinea fowl in Jamaica.
I have seen singular pale-coloured varieties imported from Barbadoes
and Demerara.
[45] For St. Domingo, _see_ M. A. Salle, in ‘Proc. Zoolog. Soc.’ 1857,
p. 236. Mr. Hill remarks to me, in his letter, on the colour of the
legs of the feral birds in Jamaica.
[46] Mr. B. P. Brent, ‘The Canary, British Finches,’ etc., pp. 21, 30.
[47] ‘Cottage Gardener,’ Dec. 11th, 1855, p. 184: an account is here
given of all the varieties. For many measurements of the wild birds,
_see_ Mr. E. Vernon Harcourt, ibid., Dec. 25th, 1855, p. 223.
[48] Bechstein, ‘Naturgesch. der Stubenvögel,’ 1840, s. 243; _see_ s.
252 on the inherited song of Canary-birds. With respect to their
baldness _see also_ W. Kidd’s ‘Treatise on Song-Birds.’
[49] W. Kidd’s ‘Treatise on Song-Birds,’ p. 18.
[50] The ‘Indian Field,’ 1858, p. 255.
[51] Yarrell’s ‘British Fishes,’ vol. i. p. 319.
[52] Mr. Blyth in the ‘Indian Field,’ 1858, p. 255.
[53] W. F. Mayers, ‘Chinese Notes and Queries,’ Aug. 1868, p. 123.
[54] ‘Proc. Zoolog. Soc.’ May 25, 1842.)
[55] Yarrell’s ‘British Fishes,’ vol. i. p. 319.
[56] ‘Dict. Class. d’Hist. Nat.,’ tom. v. p. 276.
[57] ‘Observations in Nat. Hist.,’ 1846, p. 211. Dr. Gray has
described, in ‘Annals and Mag. of Nat. Hist.,’ 1860, p. 151 a nearly
similar variety but destitute of a dorsal fin.
[58] ‘De l’Espèce,’ 1859, p. 459. With respect to the bees of Burgundy
_see_ M. Gerard, art. ‘Espèce,’ in ‘Dict. Univers. d’Hist. Nat.’
[59] _See_ a discussion on this subject, in answer to a question of
mine, in ‘Journal of Horticulture,’ 1862, pp. 225-242; also Mr. Bevan
Fox, in ditto, 1862, p. 284.
[60] This excellent observer may be implicitly trusted; _see_ ‘Journal
of Horticulture,’ July 14th, 1863, p. 39.
[61] ‘Journal of Horticulture,’ Sept. 9th, 1862, p. 463; _see also_
Herr Kleine on same subject (Nov. 11th, p. 643, who sums up, that,
though there is some variability in colour, no constant or perceptible
differences can be detected in the bees of Germany.
[62] Mr. Woodbury has published several such accounts in ‘Journal of
Horticulture,’ 1861 and 1862.
[63] ‘Annals and Mag. of Nat. Hist.,’ 3rd series, vol. xi. p. 339.
[64] ‘The Cottage Gardener,’ May 1860, p. 110; and ditto in ‘Journal
of Hort.,’ 1862, p. 242.
[65] ‘Transact. Entomolog. Soc.’ 3rd series, vol. iii. pp. 143-173 and
pp. 295-331.
[66] Godron, ‘De l’Espèce,’ 1859, tom. i. p. 460. The antiquity of the
silkworm in China is given on the authority of Stanislas Julien.
[67] _See_ the remarks of Prof. Westwood, Gen. Hearsey and others at
the meeting of the Entomolog. Soc. of London, July, 1861.
[68] _See_ for instance M. A. de Quatrefages’ ‘Études sur les Maladies
actuelles du Ver à Soie,’ 1859, p. 101.
[69] My authorities for the statements will be given in the chapter on
Selection.
[70] ‘Manuel de l’Éducateur de Vers à Soie,’ 1848.
[71] Robinet, ibid., pp. 12, 318. I may add that the eggs of N.
American silkworms taken to the Sandwich Islands produced moths at
very irregular periods; and the moths thus raised yielded eggs which
were even worse in this respect. Some were hatched in ten days, and
others not until after the lapse of many months. No doubt a regular
early character would ultimately have been acquired. _See_ review in
‘Athenæum,’ 1844, p. 329, of J. Jarves’ ‘Scenes in the Sandwich
Islands.’
[72] ‘The Art of rearing Silk-worms,’ translated from Count Dandolo,
1825, p. 23.
[73] ‘Transact. Ent. Soc.,’ ut supra, pp. 153, 308.
[74] Robinet, ibid., p. 317.
[75] Robinet, ibid., pp. 306-317.
[76] ‘Transact. Ent. Soc.,’ ut supra, p. 317.
[77] Stephen’s Illustrations, ‘Haustellata,’ vol. ii. p. 35. _ See
also_ Capt. Hutton, ‘Transact. Ent. Soc.,’ ibid., p. 152.
[78] ‘Études sur les Maladies du Ver à Soie,’ 1859, pp. 304, 209.
[79] Quatrefages, ‘Études,’ etc., p. 214.
[80] ‘Transact. Ent. Soc.,’ ut supra, p. 151.
[81] ‘Manuel de l’Educateur,’ etc., p. 26.
[82] Godron, ‘De l’Espèce,’ p. 462.
[83] Quatrefages, ‘Études,’ etc., pp. 12, 209, 214.
[84] Robinet, ‘Manuel,’ etc., p. 303.
[85] Robinet, ibid., p. 15.