J 



LAMARCK. \I^I 



imagination; with all their absurdities, they presen t 

 a semblance to the expressions of some modern 

 _writ£is^_ AM£/v! 



In his theory of Heredity, Lamarck postulated '^ 

 the inheritance of acquired characters, which we 

 have learned to-day is the crucial point in his whole 

 system. He did not expand Buffon's theories in 

 regard to the physical basis of Transmission. He 

 brings out the results which spring from free inter- 

 crossing, showing that according to his theory, in 

 the union of individuals which have been subjected 

 to different environments, the effects of environment 

 would be neutralized, whereas the crossing of in- 

 dividuals which had been subjected to the same 

 environment would hasten and perpetuate the trans- 

 mission of similar effects. To this principle he 

 refers the fact that the accidental changes induced 

 by the habits of men are not perpetuated, since 

 they do not occur in both parents, whereas the 

 formation of distinct races in widely different parts 

 of the world, is due to the uniformity of their 

 environment. 



Lamarck foresaw the great difficulties which would 

 arige in classification from his theory of the filiation 

 and mutability of all animal and plant types, and he 

 fully grasped the immediate bearings of the theory 

 upon the definition of species. He writes : " Nature 

 exhibits to us individuals succeeding each other, but 

 the species among them have only a relative sta- 

 bility, and are only temporarily invariable." Quatre- y 



