Chap. XVI. THE YOUNG LIKE BOTH ADULTS. 
211 
with the general rule throughout the animal king- 
dom, that is, on the males ; and that these have 
transmitted their gradually-acquired colours, either 
equally or almost equally, to their offspring of both 
sexes. 
Another point is more doubtful, namely, whether the 
successive variations first appeared in the males after 
they had become nearly mature, or whilst quite young. 
In either case sexual selection must have acted on 
the male when he had to compete with rivals for 
the possession of the female ; and in both cases the 
characters thus acquired have been transmitted to both 
sexes 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.^^ 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 Colymhus glacialis which had assumed 
w^hilst young, in a quite anomalous manner, the adult 
plumage of their parents.^^ Again, the young of the 
common swan [Cygnus olor) do not cast off their dark 
leathers 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, 
which were born pure white. These young birds were 
not albinoes, as shewn by the colour of their beaks 
‘Variation of Animals and Plants under Domestication/ vol. ii. 
p. 79. 
Charles worth, ‘ Mag. of Nat. Hist.’ vol. i. 1837, p. 305, 306. 
p 2 
