THE THEORY OF ORGANIC EVOLUTION. 437 



from generation to generation, and may through the 

 pairing of similar or suitable mates be gradually 

 increased in amount, the eliminative or selective proc- 

 ess works towards the establishment of new adapta- 

 tions and new species. 



As to that particular form of natural selection 

 which is called sexual selection, to which Darwin 

 attached so much importance especially in his later 

 work, we are compelled to shirk the discussion 

 of a difficult problem which could not be fairly 

 treated within our limits of space. Only a few 

 remarks can be made. As is well known, sexual 

 selection takes two chief forms (a) where the rival 

 males fight for the possession of a desired mate or 

 mates, and in so doing reduce the leet ; and (&) where 

 the females appear to choose certain individuals 

 from amid a crowd of suitors. The general verdict 

 seems to be that while among some animals prefer- 

 ential mating appears indisputable, its range and its 

 effectiveness in evolution are much less than Darwin 

 believed. This is well expressed in the work of 

 Darwin's magnanimous colleague, Alfred Russel 

 Wallace, who has given good reason for believing 

 that too much credit has been given to this sexual 

 selection factor. But just as the little child in a 

 sense leads the race being the expression of some 

 new variation, so we may still admit that there are 

 facts which warrant us in saying that das ewig weib- 

 liche plays a part in the upward march of life. 

 Cupid's darts as well as Death's arrows have some- 

 times evolutionary significance. 



Apart from differences of opinion as to the im- 

 portance of sexual selection, it seems fair to say 

 that the majority of naturalists continue to rely with 

 confidence on the general selective or eliminative 



