ndifferent to, and never intentionally selects, any modifications
in the skeleton. External characters, if not attended to by man,--such as
the number of the tail and wing feathers and their relative lengths, which
in wild birds are generally constant points,--fluctuate in our domestic
fowls in the same manner as the several parts of the skeleton. An
additional toe is a "point" in Dorkings, and has become a fixed character,
but is variable in {270} Cochins and Silk-fowls. The colour of the plumage
and the form of the comb are in most breeds, or even sub-breeds, eminently
fixed characters; but in Dorkings these points have not been attended to,
and are variable. When any modification in the skeleton is related to some
external character which man values, it has been, unintentionally on his
part, acted on by selection, and has become more or less fixed. We see this
in the wonderful protuberance of the skull, which supports the crest of
feathers in Polish fowls, and which by correlation has affected other parts
of the skull. We see the same result in the two protuberances which support
the horns in the horned fowl, and in the flattened shape of the front of
the skull in Hamburghs consequent on their flattened and broad
"rose-combs." We know not in the least whether additional ribs, or the
changed outline of the occipital foramen, or the changed form of the
scapula, or of the extremity of the furcula, are in any way correlated with
other structures, or have arisen from the changed conditions and habits of
life to which our fowls have been subjected; but there is no reason to
doubt that these various modifications in the skeleton could be rendered,
either by direct selection, or by the selection of correlated structures,
as constant and as characteristic of each breed, as are the size and shape
of the body, the colour of the plumage, and the form of the comb.

_Effects of the Disuse of Parts._

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