THE EVOLUTION OF SEX 13 



tunate to measure the importance of every result by 

 its relation to the theory of evolution. But with this 

 understanding I may venture upon a few suggestions. 



If a variation should arise in a hermaphroditic 

 species (already reproducing sexually) that made cross- 

 fertilization more likely than self-fertilization, and if, 

 as a rule, the hybrid condition (however this may be 

 explained) is more vigorous in the sense that it leaves 

 more offspring, such a variation would survive, other 

 things being equal. 



But the establishment of the contrivance in the 

 species by means of which it is more likely to cross- 

 fertilize, might in another sense act as a drawtack. 

 Should weak individuals appear, they, too, may be 

 perpetuated, for on crossing, their weakness is concealed 

 and their offspring are vigorous owing to then- hybrid 

 condition. The race will be the loser in so far as re- 

 cessive or weak combinations will continue to appear, 

 as they do in many small communities that have some 

 deficiency hi their race ; but it is a question whether the 

 vigor that comes from mixing may not more than com- 

 pensate for the loss due to the continual appearance of 

 weakened individuals. 



This argument applies to a supposed advantage 

 within the species. But recombination of what already 

 exists will not lead to the development of anything 

 that is essentially new. Evolution, however, is con- 

 cerned with the appearance and maintenance of new 

 characters. Admitting that sexual reproduction proved 

 an advantage to species, and especially so when com- 

 bined with a better chance of cross-fertilization, the 

 machinery would be at hand by means of which any 



