THE THEORY OF LAMARCK 37 



For this reason it has sometimes been thought that 

 Darwin scarcely accorded to Lamarck the appreciation 

 which he deserved ; and yet Darwin himself fell back 

 upon the Lamarckian explanation on the few occasions 

 when natural selection seemed to have failed him. 



When, however, we come to know more of the actual 

 facts of sexual generation, we find that it is very 

 difficult, if not impossible, to imagine any kind of 

 mechanism by which this supposed transmission of 

 acquired modifications can take place. We shall defer 

 the further discussion of this subject, as well as the 

 question of the existence of direct and other evidence 

 of use inheritance, until the latter half of the next 

 chapter, where we shall refer briefly to the contro- 

 versy upon these subjects which followed the estab- 

 lishment of the principle of natural selection. 



