both cases (a widow-finch and a silver
pheasant) the long tail-plumes are the indication of sexual maturity.
Such cases do not support the idea that males with the tail-feathers a
trifle longer, or the colours a trifle brighter, are generally
preferred, and that those which are only a little inferior are as
generally rejected,--and this is what is absolutely needed to establish
the theory of the development of these plumes by means of the choice of
the female.

It will be seen, that female birds have unaccountable likes and dislikes
in the matter of their partners, just as we have ourselves, and this may
afford us an illustration. A young man, when courting, brushes or curls
his hair, and has his moustache, beard, or whiskers in perfect order,
and no doubt his sweetheart admires them; but this does not prove that
she marries him on account of these ornaments, still less that hair,
beard, whiskers, and moustache were developed by the continued
preferences of the female sex. So, a girl likes to see her lover well
and fashionably dressed, and he always dresses as well as he can when he
visits her; but we cannot conclude from this that the whole series of
male costumes, from the brilliantly coloured, puffed, and slashed
doublet and hose of the Elizabethan period, through the gorgeous coats,
long waistcoats, and pigtails of the early Georgian era, down to the
funereal dress-suit of the present day, are the direct result of female
preference. In like manner, female birds may be charmed or excited by
the fine display of plumage by the males; but there is no proof whatever
that slight differences in that display have any effect in determining
their choice of a partner.

_Display of Decorative Plumage._

The extraordinary manner in which most birds display their plumage at
the time of courtship, apparently with the full knowledge that it is
beautiful, constitutes one of Mr. Darwin's strongest arguments. It is,
no doubt, a very curious and interesting phenomenon, and indicates a
connection between the exertion of particular muscles and the
development of colour and ornament; but, for the reasons just given, it
does not prove that the ornament has been developed by female choice.
During excitement, and when the organism develops superabundant energy,
many animals find it pleasurable to exercise their various muscles,
often in fantastic ways, as seen in the gambols of kittens, lambs, and
other young animals. But at the time o