12 THE DARWINIAN HYPOTHESIS i 



the attempt to gratify such desires will result in an 

 appropriate modification of the organs exerted. 

 Make a man a blacksmith, and his brachial muscles 

 will develop in accordance with the demands made 

 upon them, and in like manner, says Lamarck, 

 "the efforts of some short-necked bird to catch 

 fish without wetting himself have, with time and 

 perseverance, given rise to all our herons and 

 long-necked waders." 



The Lamarckian hypothesis has long since been 

 justly condemned, and it is the established prac- 

 tice for every tyro to raise his heel against the 

 carcase of the dead lion. But it is rarely either 

 wise or instructive to treat even the errors of a 

 really great man with mere ridicule, and in the 

 present case the logical form of the doctrine stands 

 on a very different footing from its substance. 



If species have really arisen by the operation 

 of natural conditions, we ought to be able to find 

 those conditions now at work ; we ought to be 

 able to discover in nature some power adequate 

 to modify any given kind of animal or plant in 

 such a manner as to give rise to another kind, 

 which would be admitted by naturalists as a 

 distinct species. Lamarck imagined that he had 

 discovered this vera causa in the admitted facts 

 that some organs may be modified by exercise ; 

 and that modifications, once produced, are capable 

 of hereditary transmission. It does not seem to 

 have occurred to him to inquire whether there is 



