Chapter VII: Fowls (3)

Judging from the habits of our European gallinaceous birds, _Gallus
bankiva_ in its native haunts would use its legs and wings more than do
our domestic fowls, which rarely fly except to their roosts. The Silk
and the Frizzled fowls, from having imperfect wing-feathers, cannot fly
at all; and there is reason to believe that both these breeds are
ancient, so that their progenitors during many generations cannot have
flown. The Cochins, also, from their short wings and heavy bodies, can
hardly fly up to a low perch. Therefore in these breeds, especially in
the two first, a considerable diminution in the wing-bones might have
been expected, but this is not the case. In every specimen, after
disarticulating and cleaning the bones, I carefully compared the
relative length of the two main bones of the wing to each other, and of
the two main bones of the leg to each other, with those of _G.
bankiva_; and it was surprising to see (except in the case of the
tarsi) how exactly the same relative length had been retained. This
fact is curious, from showing how truly the proportions of an organ may
be inherited, although not fully exercised during many generations. I
then compared in several breeds the {271} length of the femur and tibia
with the humerus and ulna, and likewise these same bones with those of
_G. bankiva_; the result was that the wing-bones in all the breeds
(except the Burmese Jumper, which has unnaturally short legs) are
slightly shortened relatively to the leg-bones; but the decrease is so
slight that it may be due to the standard specimen of _G. bankiva_
having accidentally had wings of slightly greater length than usual; so
that the measurements are not worth giving. But it deserves notice that
the Silk and Frizzled fowls, which are quite incapable of flight, had
their wings _less_ reduced relatively to their legs than in almost any
other breed! We have seen with domesticated pigeons that the bones of
the wings are somewhat reduced in length, whilst the primary feathers
are rather increased in length, and it is just possible, though not
probable, that in the Silk and Frizzled fowls any tendency to decrease
in the length of the wing-bones from disuse may have been checked
through the law of compensation, by the decreased growth of the
wing-feathers, and consequent increased supply of nutriment. The
wing-bones, however, in both these breeds, are found to be slightly
reduced in length when judged by the standard of the length of the
sternum or head, relatively to these same parts in _G. bankiva_.

The actual weight of the main bones of the leg and wing in twelve
breeds is given in the two first columns in the following table. The
calculated weight of the wing-bones relatively to the leg-bones, in
comparison with the leg and wing-bones of _G. bankiva_, are given in
the third column,--the weight of the wing-bones in _G. bankiva_ being
called a hundred.[433]

TABLE I.

+----------------------------------+---------+---------+----------------+
| | | | Weight of |
| | Actual | Actual | Wingbones |
| | Weight | Weight | relatively to |
| Names of Breeds. | of | of | the Leg-bones, |
| | Femur | Humerus | in comparison |
| | and | and | with these |
| | Tibia. | Ulna. | same bones in |
| | Grains. | Grains. | G. bankiva. |
+--+-------------------------------+---------+---------+----------------+
| |Gallus bankiva wild male | 86 | 54 | 100 |
| 1|Cochin male | 311 | 162 | 83 |
| 2|Dorking male | 557 | 248 | 70 |
| 3|Spanish (Minorca) male | 386 | 183 | 75 |
| 4|Gold Spangled Polish male | 306 | 145 | 75 |
| 5|Game, black-breasted male | 293 | 143 | 77 |
| 6|Malay female | 231 | 116 | 80 |
| 7|Sultan male | 189 | 94 | 79 |
| 8|Indian Frizzled male | 206 | 88 | 67 |
| 9|Burmese Jumper female | 53 | 36 | 108 |
|10|Hamburgh (pencilled) male | 157 | 104 | 106 |
|11|Hamburgh (pencilled) female | 114 | 77 | 108 |
|12|Silk (black-boned) female | 88 | 57 | 103 |
+--+-------------------------------+---------+---------+----------------+

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In the eight first birds, belonging to distinct breeds, in this table,
we see a decided reduction in the weight of the bones of the wing. In
the Indian Frizzled fowl, which cannot fly, the reduction is carried to
the greatest extent, namely, to thirty-three per cent. of their proper
proportional weight. In the next four birds, including the Silk-hen,
which is incapable of flight, we see that the wings, relatively to the
legs, are slightly increased in weight; but it should be observed that,
if in these birds the legs had become from any cause reduced in weight,
this would give the false appearance of the wings having increased in
relative weight. Now a reduction of this nature has certainly occurred
with the Burmese Jumper, in which the legs are abnormally short, and in
the two Hamburghs and Silk fowl, the legs, though not short, are formed
of remarkably thin and light bones. I make these statements, not
judging by mere eyesight, but after having calculated the weights of
the leg-bones relatively to those of _G. bankiva_, according to the
only two standards of comparison which I could use, namely, the
relative lengths of the head and sternum; for I do not know the weight
of the body in _G. bankiva_, which would have been a better standard.
According to these standards, the leg-bones in these four fowls are in
a marked manner far lighter than in any other breed. It may therefore
be concluded that in all cases in which the legs have not been through
some unknown cause much reduced in weight, the wing-bones have become
reduced in weight relatively to the leg-bones, in comparison with those
of _G. bankiva_. And this reduction of weight may, I apprehend, safely
be attributed to disuse.

To make the foregoing table quite satisfactory, it ought to have been
shown that in the eight first birds the leg-bones have not actually
increased in weight out of due proportion with the rest of the body;
this I cannot show, from not knowing, as already remarked, the weight
of the wild Bankiva.[434] I am indeed inclined to suspect that the
leg-bones in the Dorking, No. 2 in the table, are proportionally too
heavy; but this bird was a very large one, weighing 7 lb. 2 oz., though
very thin. Its leg-bones were more than ten times as heavy as those of
the Burmese Jumper! I tried to ascertain the length both of the
leg-bones and wing-bones relatively to other parts of the body and
skeleton; but the whole organisation in these birds, which have been so
long domesticated, has become so variable, that no certain conclusions
could be reached. For instance, the legs of the above Dorking cock were
nearly three-quarters of an inch too short relatively to the length of
the sternum, and more than {273} three-quarters of an inch too long
relatively to the length of the skull, in comparison with these same
parts in _G. bankiva_.

In the following Table II. in the two first columns we see in inches
and decimals the length of the sternum, and the extreme depth of its
crest to which the pectoral muscles are attached. In the third column
we have the calculated depth of the crest, relatively to the length of
the sternum, in comparison with these same parts in _G. bankiva_.[435]

TABLE II.

+-----------------------------+-----------+------------+----------------+
| | | | Depth of Crest,|
| | | | relatively to |
| | Length | Depth of | the length of |
| Names of Breeds. | of | Crest | the Sternum in |
| | Sternum. | of Sternum.| comparison with|
| | | | G. bankiva. |
+--+--------------------------+-----------+------------+----------------+
| | | Inches. | Inches. | |
| |Gallus bankiva male | 4.20 | 1.40 | 100 |
| 1|Cochin male | 5.83 | 1.55 | 78 |
| 2|Dorking male | 6.95 | 1.97 | 84 |
| 3|Spanish male | 6.10 | 1.83 | 90 |
| 4|Polish male | 5.07 | 1.50 | 87 |
| 5|Game male | 5.55 | 1.55 | 81 |
| 6|Malay female | 5.10 | 1.50 | 87 |
| 7|Sultan male | 4.47 | 1.36 | 90 |
| 8|Frizzled hen male | 4.25 | 1.20 | 84 |
| 9|Burmese Jumper female | 3.06 | 0.85 | 81 |
|10|Hamburgh male | 5.08 | 1.40 | 81 |
|11|Hamburgh female | 4.55 | 1.26 | 81 |
|12|Silk fowl female | 4.49 | 1.01 | 66 |
+--+--------------------------+-----------+------------+----------------+

By looking to the third column we see that in every case the depth of
the crest relatively to the length of the sternum, in comparison with
_G. bankiva_, is diminished, generally between 10 and 20 per cent. But
the degree of reduction varies much, partly in consequence of the
frequently deformed state of the sternum. In the Silk-fowl, which
cannot fly, the crest is 34 per cent. less deep than what it ought to
have been. This reduction of the crest in all the breeds probably
accounts for the great variability, before referred to, in the
curvature of the furcula, and in the shape of its sternal extremity.
Medical men believe that the abnormal form of the spine so commonly
observed in women of the higher ranks results from the attached muscles
not being fully exercised. So it is with our domestic fowls, for they
use their pectoral muscles but little, and, out of twenty-five sternums
examined by me, three alone were perfectly symmetrical, ten were
moderately crooked, and twelve were deformed to an extreme degree.

Finally, we may conclude with respect to the various breeds of the fowl, that the main bones of the wing have probably been shortened in a very slight degree; that they have {274} certainly become lighter relatively to the leg-bones in all the breeds in which these latter bones are not unnaturally short or delicate; and that the crest of the sternum, to which the pectoral muscles are attached, has invariably become less prominent, the whole sternum being also extremely liable to deformity. These results we may attribute to the lessened use of the wings.

_Correlation of Growth_.--I will here sum up the few facts which I have collected on this obscure, but important, subject. In Cochins and Game-fowls there is some relation between the colour of the plumage and the darkness of the egg-shell and even of the yolk. In Sultans the additional sickle-feathers in the tail are apparently related to the general redundancy of the plumage, as shown by the feathered legs, large crest, and beard. In two tailless fowls which I examined the oil-gland was aborted. A large crest of feathers, as Mr. Tegetmeier has remarked, seems always accompanied by a great diminution or almost entire absence of the comb. A large beard is similarly accompanied by diminished or absent wattles. These latter cases apparently come under the law of compensation or balancement of growth. A large beard beneath the lower jaw and a large top-knot on the skull often go together. The comb when of any peculiar shape, as with Horned, Spanish, and Hamburgh fowls, affects in a corresponding manner the underlying skull; and we have seen how wonderfully this is the case with Crested fowls when the crest is largely developed. With the protuberance of the frontal bones the shape of the internal surface of the skull and of the brain is greatly modified. The presence of a crest influences in some unknown way the development of the ascending branches of the premaxillary bone, and of the inner processes of the nasal bones; and likewise the shape of the external orifice of the nostrils. There is a plain and curious correlation between a crest of feathers and the imperfectly ossified condition of the skull. Not only does this hold good with nearly all crested fowls, but likewise with tufted ducks, and as Dr. Guenther informs me with tufted geese in Germany.

Lastly, the feathers composing the crest in male Polish fowls resemble hackles, and differ greatly in shape from those in the crest of the female. The neck, wing-coverts, and loins {275} in the male bird are properly covered with hackles, and it would appear that feathers of this shape have spread by correlation to the head of the male. This little fact is interesting; because, though both sexes of some wild gallinaceous birds have their heads similarly ornamented, yet there is often a difference in the size and shape of feathers forming their crests. Furthermore there is in some cases, as in the male Gold and in the male Amherst pheasants (_P. pictus_ and _Amherstiae_), a close relation in colour, as well as in structure, between the plumes on the head and on the loins. Hence it would appear that the same law has regulated the state of the feathers on the head and body, both with species living under their natural conditions, and with birds which have varied under domestication.

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