274 EVOLUTION OF TO-DAY, 



tions. Thus an individual, A, may show in its adult 

 condition some new feature, and its offspring, A, 1 

 may show the same. The ordinary interpretation 

 would be. that A transmitted this feature to A 1 . 

 But Weismann would say that the ovum from which 

 A developed varied in such a manner that this new 

 feature appeared in the adult. And since A was 

 developed from one half of this ovum, and A 1 from 

 the other half, the same feature would appear in 

 both, and would then seem to be transmitted from 

 one to the other. Weismann further believes that the 

 ovum is especially subject to variation, being readily 

 influenced by many circumstances. There are con- 

 stantly arising variations which are transmitted from 

 generation to generation, but they are all derived 

 from variations of the ovum and never of the adult. 

 It is evident that with this explanation of heredity 

 no chance is left for the inherited effects of use and 

 disuse. Since no acquired feature is inherited, it 

 would make no difference how much an organ was in- 

 creasd by use or diminished by disuse; it would have 

 no effect on the next generation. Congenital varia- 

 tions alone /. e., those arising in the egg can be 

 inherited. But to accept this position Weismann 

 is obliged to explain away many cases of well- 

 attested facts. The blind eyes of some animals is 

 only explained by a loss of function and size by dis- 

 use. There are a number of cases on record where 

 accidental mutilations are inherited, although this, 

 as a rule, is not the case. The numerous instances 

 of this kind are sufficient to show that Weismann's 

 theory is not wholly correct. But even more than 



