CHAPTER XIV.

Birds--continued.

Choice exerted by the female--Length of courtship--Unpaired birds--Mental
qualities and taste for the beautiful--Preference or antipathy shewn by the
female for particular males--Variability of birds--Variations sometimes
abrupt--Laws of variation--Formation of ocelli--Gradations of character--
Case of Peacock, Argus pheasant, and Urosticte.


CHAPTER XV.

Birds--continued.

Discussion as to why the males alone of some species, and both sexes of
others are brightly coloured--On sexually-limited inheritance, as applied
to various structures and to brightly-coloured plumage--Nidification in
relation to colour--Loss of nuptial plumage during the winter.


CHAPTER XVI.

Birds--concluded.

The immature plumage in relation to the character of the plumage in both
sexes when adult--Six classes of cases--Sexual differences between the
males of closely-allied or representative species--The female assuming the
characters of the male--Plumage of the young in relation to the summer and
winter plumage of the adults--On the increase of beauty in the birds of the