160 SEXUAL selection: birds. PartIL 



inheritance from tTie males any marked accession of 

 briolitness, would sooner or later be destroyed. But 

 the tendency in the males to continue for an indefinite 

 period transmitting to their female offspring their own 

 brightness, would have to be eliminated by a change in 

 the form of inheritance; and this, as shewn by our 

 previous illustration, would be extremely difficult. The 

 more probable result of the long-continued destruction 

 of the more brightly-coloured females, supposing the 

 equal form of transmission to prevail, would be the les- 

 sening or annihilation of the bright colours of the males, 

 owinoj to their continuallv crossino- with the duller 

 females. It would be tedious to follow out all the 

 other possible results ; but I may remind the reader, as 

 shewn in the eighth chapter, that if sexually-limited 

 variations in brightness occurred in the females, even if 

 they were not in the least injurious to them and con- 

 sequently were not eliminated, yet they would not be 

 favoured or selected, for the male usually accepts any 

 female, and does not select the more attractive indi- 

 viduals ; consequently these variations would be liable 

 to be lost, and would have little influence on the 

 character of the race ; and this will aid in account- 

 ing for the females being commonly less brightly- 

 coloured than the males. 



In the chapter just referred to, instances were given, 

 and any number might have been added, of variations 

 occurring at different ages, and inherited at the same 

 i\ge. It was also shewn that variations which occur late 

 in life are commonly transmitted to the same sex in 

 which the}'' first appeared ; whilst variations occurring 

 early in life are apt to be transmitted to both sexes ; 

 not that all the cases of sexually-limited transmission 

 can thus be accounted for. It was further shewn that 

 if a male bird varied by becoming brighter whilst 



