Alfred Russel Wallace 



To answer your first question is most difficult, if not 

 impossible, because we have no sufficient evidence in in- 

 dividual cases of slight sexual difference, to determine 

 whether the male alone has acquired his superior bright- 

 ness by sexual selection, or the female been made duller 

 by need of protection, or whether the two causes have 

 acted. Many of the sexual differences of existing species 

 may be inherited differences from parent forms who existed 

 under different conditions and had greater or less need of 

 protection. 



I think I admitted before the general tendency (probably) 

 of males to acquire brighter tints. Yet this cannot be uni- 

 versal, for many female birds and quadrupeds have equally 

 bright tints. 



I think the case of $ Pieris pyrrha proves that females 

 alone can be greatly modified for protection. 



To your second question I can reply more decidedly. I 

 do think the females of the Gallinaceae you mention have 

 been modified or been prevented from acquiring the 

 brighter plumage of the male by need of protection. I 

 know that the Gallus danJciva frequents drier and more 

 open situations than the pea- hen of Java, which is found 

 among grassy and leafy vegetation corresponding with the 

 colours of the two. So the Argus pheasant, $ and ? , are, 

 I feel sure, protected by their tints corresponding to the 

 dead leaves of the lofty forest in which they dwell, and the 

 female of the gorgeous fire-back pheasant, Lophura viellottii^ 

 is of a very similar rich hrown colour, I do not, however, 

 at all think the question can be settled by individual caseg, 

 but only by large masses of facts. 



The colours of the mass of female birds seem to me 

 strictly analogous to the colours of both sexes of snipes, 

 woodcocks, plovers, etc., which are undoubtedly protective. 



Now, supposing, on your view, that the colours of a 



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