156 THEORY OF EVOLUTION 



ing to his views. His contemporaries and 

 many of his followers, however, appear to have 

 accepted this sliding scale interpretation as 

 the cardinal doctrine of evolution. If this is 

 doubted or my statement is challenged then 

 one must explain why de Vries' mutation the- 

 ory met with so little enthusiasm amongst the 

 older group of zoologists and botanists; and 

 one must explain why Johannsen's splendid 

 work met with such bitter opposition from 

 the English school the biometricians who 

 amongst the post-Darwinian school are as- 

 sumed to be the lineal descendants of Darwin. 

 And in this connection we should not forget 

 that just this sort of process was supposed to 

 take place in the inheritance of use and disuse. 

 What is gained in one generation forms the 

 basis for further gains in the next generation. 

 Now, Darwin not only believed that acquired 

 characters are inherited but turned more and 

 more to this explanation in his later writings. 

 Let us, however, not make too much of the 

 matter ; for it is much less important to find out 

 whether Darwin's ideas were vague, than it is 

 to make sure that our own ideas are clear. 



