196 SEXUAL SELECTION : BIRDS. Part II. 



auritum and Phasianus Wallicliii) the two sexes closely 

 resemble each other and their colours are dull. We 

 may go so far as to believe that if any part of the 

 plumage in the males of these two pheasants had been 

 brilliantly coloured, this would not have been transferred 

 to the females. These facts strongly support Mr. 

 Wallace's view that with birds which are exposed to 

 much danger during nidification, the transference of 

 bright colours from the male to the female has been 

 checked through natural selection. We must not, 

 however, forget that another explanation, before given, 

 is possible ; namely, that the males which varied and 

 became bright, whilst they were young and inex- 

 perienced, would have been exposed to much danger, 

 and would generally have been destroyed ; the older 

 and more cautious males, on the other hand, if they 

 varied in a like manner, would not only have been able 

 to survive, but would have been favoured in their 

 rivalry with other males. Now variations occurrinoj 

 late in life tend to be transmitted exclusively to the 

 same sex, so that in this case extremely bright tints 

 would not have been transmitted to the females. On 

 the other hand, ornaments of a less conspicuous kind, 

 such as those possessed by the Eared and Cheer phea- 

 sants, would not have been dangerous, and if they ap- 

 peared during early youth, would generally have been 

 transmitted to both sexes. 



In addition to the effects of the partial transference 

 of characters from the males to the females, some of the 

 differences between the females of closely-allied sj^ecies 

 may be attributed to the direct or definite action of 

 the conditions of life.^^ With the males any such 



" See, on this subject, chap, xxiii. in the 'Variation of Animals and 

 riantri under Doraesticatiou.' 



