ADAPTIVE VARIATIONS. 397 



mitted, a difficulty which has never been hitherto ade- 

 quately accounted for, and hence, in lieu of something 

 better, Weismann's hypothesis may in this respect be 

 provisionally accepted. Still it is always to be remem- 

 bered that it is no more than an hypothesis, which has 

 not, and never can have, any experimental evidence 

 to support it. 



