WEAKNESS OF USE-INHERITANCE. 97 



where selection is clearly inadequate to pro- 

 duce the change, or where it is scarcely allowed 

 time or opportunity to act, as in the immediate 

 offspring of the modified individual. Of the 

 first kind of cases there seems to be a plentiful 

 lack. Of the latter kind, according to Darwin, 

 there appears to be none a circumstance which 

 contrasts strangely and suspiciously with the 

 many decisive cases in which variation from 

 unknown causes has been inherited most strik- 

 ingly in the immediate offspring. It must be 

 expected, indeed, that among these innumer- 

 able cases some will accidentally mimic the 

 alleged effects of use-inheritance. 



If Darwin had felt certain that the effects 

 of habit or use tended in any marked degree 

 to be conveyed directly and cumulatively to 

 succeeding generations, he could hardly have 

 given us such cautious, half-hearted encourage- 

 ment of good habits as the following: "Jt 



H 



