The Descent of Man

and all ages. But these characters if acquired by
the males when adult, may have been transmitted
at first to the adults alone, and at some subsequent
period transferred to the young. For it
is known that, when the law of inheritance at
corresponding ages fails, the offspring often
inherit characters at an earlier age than that at
which they first appeared in their parents. (30.
'Variation of Animals and Plants under Domestication,'
vol. ii. p. 79.) Cases apparently of this
kind have been observed with birds in a state of
nature. For instance Mr. Blyth has seen specimens
of Lanius rufus and of Colymbus glacialis
which had assumed whilst young, in a quite
anomalous manner, the adult plumage of their
parents. (31. 'Charlesworth's Magazine of Natural
History,' vol. i. 1837, pp. 305, 306.) Again,
the young of the common swan (Cygnus olor)
do not cast off their dark feathers and become
white until eighteen months or two years old;
but Dr. F. Forel has described the case of three
vigorous young birds, out of a brood of four,