CiiAP. XVI. THE YOUNG LIKE BOTH ADULTS. 211 



with the general rule tliroughout the animal king- 

 dom, that is, on the males ; and that these have 

 ransmitted 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 fii'st 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 chai'acters 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 Cohjmbus glacialis which had assumed 

 whilst young, in a quite anomalous manner, the adult 

 plumage of their pareuts.^^ Again, the young of the 

 common swan {Oijgnus 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, 

 wliich were born pure wdiite. These young birds were 

 not albinoes, as shewn by the colour of their beaks 



30 'Variation of Animals and Plants under Domestication,' vol. ii. 

 p. 79. 



31 Charlesworth, ' Mag. of Nat. Hist.' vol. i. 1837, p. 305, 306. 



P '1 



