yellowish-brown in the male, and into bright red in the female. The
male has also a small, longitudinal, leaden-coloured, fleshy crest or
comb. The comb of many gallinaceous birds is highly ornamental, and
assumes vivid colours during the act of courtship; but what are we to
think of the dull-coloured comb of the condor, which does not appear to
us in the least ornamental? The same question may be asked in regard to
various other characters, such as the knob on the base of the beak of
the Chinese goose (Anser cygnoides), which is much larger in the male
than in the female. No certain answer can be given to these questions;
but we ought to be cautious in assuming that knobs and various fleshy
appendages cannot be attractive to the female, when we remember that
with savage races of man various hideous deformities deep scars on the
face with the flesh raised into protuberances, the septum of the nose
pierced by sticks or bones, holes in the ears and lips stretched widely
open are all admired as ornamental.
Whether or not unimportant differences between the sexes, such as those
just specified, have been preserved through sexual selection, these
differences, as well as all others, must primarily depend on the laws
of variation. On the principle of correlated development, the plumage
often varies on different parts of the body, or over the whole body, in
the same manner. We see this well illustrated in certain breeds of the
fowl. In all the breeds the feathers on the neck and loins of the males
are elongated, and are called hackles; now when both sexes acquire a
top-knot, which is a new character in the genus, the feathers on the
head of the male become hackle-shaped, evidently on the principle of
correlation; whilst those on the head of the female are of the ordinary
shape. The colour also of the hackles forming the top-knot of the male,
is often correlated with that of the hackles on the neck and loins, as
may be seen by comparing these feathers in the golden and
silver-spangled Polish, the Houdans, and Creve-coeur breeds. In some
natural species we may observe exactly the same correlation in the
colours of these same feathers, as in the males of the splendid Gold
and Amherst pheasants.
The structure of each individual feather generally causes any change in
its colouring to be symmetrical; we see this in the various laced,
spangled, and pencilled breeds of the fowl; and on the principle of
correlation the feathers over the whole body are often coloured in the
same manner. We are thus enabled without much trouble to rear breeds
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