98 HEREDITY AND SELECTION IN SOCIOLOGY 



of generations ; since the species themselves would have to dis- 

 appear before amphimixis could disappear. 



Thus the objection that, as amphimixis does not directly benefit 

 the individuals of the species which exhibit it, therefore natural 

 selection is not interested in its maintenance, and therefore 

 amphimixis is not exclusively a product of selection, omits to 

 take certain factors into consideration. Natural selection, it is 

 said, cannot interest itself (metaphorically speaking) in the 

 maintenance of a character which is not directly useful to the 

 species ; and it cannot be said that the usefulness of amphimixis 

 is anything but intermittent and indirect, in so far as its raison 

 d'etre is the adaptation of the species to new conditions. Adap- 

 tation to modified conditions takes place but once in every 

 thousand generations, or even less. On the theory that func- 

 tional use or disuse strengthens or weakens a function, we can 

 suppose amphimixis to exist simply because of the vast reserve 

 of force which its long functional activity has necessarily accu- 

 mulated ; but if the transmission of functionally acquired modi- 

 fications be denied, how can we explain why amphimixis has per- 

 sisted as it has, if selection alone be responsible for it ? and if, 

 furthermore, the hypothesis of amphimixis as a rejuvenating 

 factor be rejected ? During the thousand generations or more 

 which elapse between successive adaptations of species, what 

 force can selection exercise on the maintenance of amphimixis ? 

 When the species enters into a period of instability due to the 

 changes in the environment, then amphimixis will doubtless play 

 an important role in adapting the species to the modified condi- 

 tions ; and, as amphimixis is then of direct benefit to the species, 

 natural selection wiU favour its recurrence ; but in the vast 

 periods which intervene between these crises of instabiUty due 

 to readaptation, what reason has selection to favour the main- 

 tenance of amphimixis ? 



This objection is based upon the assumption that in the in- 

 tervals between the periods of readaptation amphimixis has no 



