36 THEORY OF ORGANIC EVOLUTION. 



the idioplasm. This is perceived from the succes- 

 sion of the visible ontogenetic characteristics which 

 in general run parallel with it. The idioplasm 

 varies in two ways: (i) by an automatic perfecting 

 process; (a) by adaptation to environment. 



By virtue of the automatic variation of the idio- 

 plasm the ontogenies of a phylogenetic line attain 

 to a continually more complex organization and 

 greater differentiation of function. In this differ- 

 entiation, however, only the qualitative differences 

 are of importance; quantitative and numerical 

 gradations may be disregarded. The more complex 

 admits of more combinations than the simpler; 

 hence if a phylogeny reaches a higher stage by 

 automatic evolution it may branch into several lines, 

 of which each appears as the continuation of the 

 parent stock. 



Since adaptive variations depend only on the 

 transmutations of environment, an organism may 

 rise to a higher organization and division of labor 

 by continually adapting itself to the changed envi- 

 ronment. But the organism may also change its 

 adaptation while it remains at the same stage of 

 organization. And since the adaptive variation is 

 quickly perfected as compared with automatic evo- 

 lution, although extremely slowly as compared with 

 the duration of the ontogeny, an organization may 

 change its adaptation several times while it remains 

 at the same grade of organization and division of 



