112 DARWINISM TO-DAY. 



males and the winning of the females by the victor, are ob- 

 served facts in the life of numerous animal species. But a 

 special sexual selection theory is hardly necessary to explain 

 the development of the fighting equipment, antlers, spurs, 

 claws, etc. This fighting array of the male is simply a special 

 phase of the already recognised intra-specific struggle ; it is 

 not a fight for room or food, but for the chance to mate. 

 But this chance often depends on the issue of a life-and- 

 death struggle. Natural selection would thus account for 

 the development of the weapons for this struggle. 



For the development, however, of such secondary sexual 

 characters as ornament, whether of special plumage, colour, 

 pattern, or processes, and song, and special odours, and 

 "love-dancing," the natural selection theory can in no way 

 account; the theory of sexual selection was the logical and 

 necessary auxiliary theory, and when first proposed by 

 Darwin 3 met with quick and wide acceptance. Wallace in 

 particular took up the theory and applied it to explain many 

 cases of remarkable plumage and pattern development 

 among birds. Later as he analysed more carefully his cases, 

 and those proposed by others, he became doubtful, and 

 finally wholly sceptical 4 of the theory. 



The theory as proposed by Darwin was based on the fol- 

 lowing general assumptions, for the proof of each of which a 

 few to many facts were adduced. First, many 

 bases of the secondary sexual characters are not explicable 

 by natural selection ; they are not useful in the 

 struggle for life. Second, the males seek the females for 

 the sake of pairing. Third, the males are more abundant 

 than the females. Fourth, in many cases there is a struggle 

 among the males for the possession of the females. Fifth, 

 in many other cases the females choose, in general, those 

 males specially distinguished by more brilliant colours, more 

 conspicuous ornaments, or other attractive characters. 

 Sixth, many males sing, or dance, or otherwise draw to 



