538 THE DESCENT OF MAN. 



now marks of nearly the same shape have been transferred 

 to the female, but the central space is fulvous instead of 

 red and is surrounded by mottled instead of blue feathers. 

 The Grallinaceae offer many analogous cases; for none of 

 the species, such as partridges, quails, guinea-fowl, etc., 

 in which the colors of the plumage have been largely trans- 

 ferred from the male to the female, are brilliantly colored. 

 This is well exemplified with the pheasants, in which the 

 male is generally so much more brilliant than the female: 

 but with the eared and cheer pheasants (Crossoptilon 

 auritum and Phasianus wallicliii) the sexes closely resem- 

 ble each other and their colors 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 colored it 

 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 incubation, the trans- 

 ference of bright colors 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, while they were young and inexperienced, 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 

 favored in their rivalry with other males. Now variations 

 occurring 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 pheasants, would not 

 have been dangerous, and if they appeared 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 differ- 

 ences between the females of closely allied species may be 

 attributed to the direct or definite action of the conditions 

 of life.* With the males any such action would generally 



* See, on tliis subject, chap, xxiii, in the " Variation of Animals 

 and Plants under Domestication." 





