120 DARWINISM TO-DAY. 



on. It is curious that this has not been realised by those 

 who believe in both of these two hypotheses. 



"What has just been said applies also with almost equal 

 force to the development of such structures as the horns 

 of the deer, bison, antelopes, and the brilliant colours of 

 many insects and birds. If in nature, competition between 

 species takes place on the scale that the Darwinian theory 

 of natural selection postulates, such forms, if they are much 

 exposed, would be needlessly reduced in numbers in the 

 process of acquiring these structures. So many individuals 

 would have been at such a disadvantage in breeding, that 

 if competition is as severe as the theory of natural selection 

 postulates, these species could hardly be expected to compete 

 successfully with other species in which sexual selection was 

 not taking place." 



Finally to make an end of miscellaneous objections and 



come to that one which promises to be, if it is not already, 



the most serious obstacle in the way of the 



evidence Ts^p- sexual selection theory, it is a fact that all the 



posed to sexual evidence (though it be little as yet) based on 



selection theory. ' . 



actual experiment is strongly opposed to the 



validity of the assumption that the females make a choice 

 among males based on the presence in the males of ornament 

 or attractive colours, pattern, or special structures. I may 

 mention especially the striking experiments of Mayer 8 

 (which, published in a small entomological journal of 

 limited circulation, have not received the attention that they 

 deserve) on the large Bombycine moth, Callosamia pro- 

 methea. This well-known American moth expands about 

 three and one-half inches and shows unusually pronounced 

 secondary sexual differences as to colour and pattern. The 

 females are reddish-brown in ground colour, while the males 

 are blackish and in the two sexes the pattern is distinctly 

 different. If there is any moth species in which the colours 

 and general pattern of the male ought to be readily obvious 



