The Descent of Man

of the equal transmission of characters to both
sexes, into transmission to the male sex alone. It
is also doubtful whether the colours of many
female birds are due to the preservation, for the
sake of protection, of variations which were
from the first limited in their transmission to
the female sex. But it will be convenient to defer
any further discussion on this subject until I
treat, in the following chapter, of the differences
in plumage between the young and old.
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