SEXUAL SELEOTIOy 677 



the fancy that this should always be the case, and succesa 

 has quickly followed the order. Now the lopping of the 

 comb must be sexually limited in its transmission, other- 

 wise it would prevent the comb of the male from being 

 perfectly upright, which would be abhorrent to every fan- 

 cier. On the other hand, the uprightness of the comb in 

 the male must likewise be a sexually limited character, 

 otherwise it would prevent the comb of the female from 

 lopping over. 



From the f(»«going illustrations, we see that, even with 

 almost unlimited time at command, it would be aa extremely 

 difficult and complex, perhaps an impossible, process to 

 change one form of transmission into the other through 

 selection. Therefore, without distinct evidence in each 

 case, I am unwilling to admit that this has been effected 

 in natural species. On the other hand, by means of suc- 

 cessive variations, which were from the first sexually lim- 

 ited in their transmission, there would not be the least diffi- 

 culty in rendering a male bird widely different in color or 

 in any other character from the female; the latter being left 

 unaltered, or slightly altered, or specially modified for the 

 sake of protectioa. 



As bright colors are of service to the males in their 

 rivalry with other males, such colors would be selected, 

 whether or not they were transmitted exclusively to the 

 same sex. Consequently the females might be expected 

 often to partake of the brightness of the males to a greater 

 or less degree; and this occurs with a host of species. 11 

 all the successive variations were transmitted equally to 

 both sexes, the females would be indistinguishable from 

 the males; and this likewise occurs with many birds. If, 

 however, dull colors were of high importance for the safety 

 of the female during incubation, as with many ground birds, 

 the females which varied in brightness, or which received 

 through inheritance from the males any marked accession 

 of brightness, would sooner or later be destroyed. But the 

 tendency in the males to continue for an indefinite period 



