in Animals as afforded by Observations on certain Salmonids. 285 



outward appearance, and that where the sexes differ the more 

 powerful or highly coloured is that in which the influence of the 

 generative organs has had its full force on the development of 

 pigment, of muscle, or of particular regions of the body, while in 

 the weaker or more dully-coloured sex the same processes have 

 been restricted for protective reasons. That the latter should 

 be usually the female is not, I think, surprising when we consider 

 her usually different functions in the care of her offspring and in 

 other respects, but I think I have made it clear, if proof were 

 needed, that either sex may be the more highly developed. 



The decoration of birds like the Peacock or the male Pheasant 

 I would regard as a possibly permanent assumption by the sexually 

 mature male of ornaments which in many species are only as- 

 sumed temporarily. Even in these familiar cases, however, the 

 decorations are not really, but only comparatively permanent, 

 since their assumption begins and ends with the strong functional 

 activity of the generative organs. 



Lastly, if, as I suggest, each sex has naturally a similar capacity 

 for the production of nuptial changes, we should surely need to 

 account in some way for the failure to produce them in one or 

 other sex of so many animals. I suggest that the excess of pig- 

 ment may be disposed of, at least in the case of females, in many 

 ways, such as in the pigmented eggs of Birds, or in the excrement, 

 urine, and in the menstrual discharges and young of placental 

 Mammals. 



