218 
SEXUAL SELECTION: BIRDS. 
PaR 1 1 
waders. Lastly, in regard to tlie young di 
greatly from both sexes in their adult summer 
winter plumages, this occurs with some herons ‘ ll1 ' 
egrets of North America and India, — the young 
being white. 
I will mako only a few remarks on these eompli 011 ^ 
cases. When the young resemble the female in ^ 
summer dress, or the adults of both sexes in their win^ 
dress, the cases differ from those given under Classes * 
and III. only in the characters originally acquired V 
the males during the breeding-season, having l ,eti 
Imited in their transmission to the corresponding se®®^ 
When the adults have a distinct summer and wkdf 
plumage, and the young- differ from both, the case " 
more difficult to understand. We may admit as P 1 ^ 
bable that the young have retained an ancient sh lt ' 
of plumage ; we can account through sexual sele 0tl< \ 
tor the summer or nuptial plumage of the adults? ^ 
how are we to account for their distinct winter plmuag' 0 ' 
If we could admit that this plumage serves in all 
as a protection, its acquirement would he a sii»W 
affair , but there seems no good reason for this ,l 
mission. It may be suggested that the widely diffe reJ * 
conditions ol life during the winter and summer b# v 
acted in a direct manner on the plumage; this 
have had some effect, but I have not much confid® BC 
in so great a difference, as we sometimes see, bet"' 01 ' 
the two plumages having been thus caused. A 1001 
probable explanation is, that an ancient style of plutB 1 ^ 1 ^ 
partially modified through the transference of 
characters from the summer plumage, has been reta' B< 
by the adults during the winter. Finally, all the 
in our pieseut class apparently depend on c-hara 0 ! 0 
•iouS 
acquired by the adult males, having been var 
limited in their transmission accordino- to age, se® 
;lf 
ISO 0 ' 
