180 OEGANIC EVOLUTION — IVIENTAL 



mental atmosphere in whicli the two children are 

 respectively nurtured." — lUd. p. 178. 



Now, since so little in man that is mental is inborn, 

 and so much is acquired, deductively it seems probable 

 that Mr. Buckle is right. It may, however, be argued, 

 that since survival of the fittest has caused in different 

 environments the various races of mankind to differ as 

 regards their physical characters, it is highly likely 

 that it has caused them to differ as regards their mental 

 characters also. But here crops up that old and fertile 

 source of error, the idea th-at the mind is an organ, not 

 merely the product of the functional activity of an 

 organ. The mind is the product of the functional 

 activity of the nervous tissue, mainly of the brain, and 

 therefore is comparable, not to other organs, but to the 

 products of their functional activities, using the words 

 in their widest sense. The brains- of various races differ 

 in size and shape, and may differ structurally in many 

 other respects, not as yet observed by us, and these 

 differences have possibly or probably for their concomi- 

 tants mental differences of more or, less importance, but 

 it is doubtful whether these latter are of the kind 

 commonly supposed. 



We have seen that organic evolution consists essen- 

 tially of a process of gradual structural modification, 

 whereby evolving species are brought into harmony 

 with environments gradually increasing in complexity. 

 Counting from unicellular organisms, the process began 

 with the evolution of multicellular organisms, was con- 

 tinued by the evolution of complex and heterogeneous 

 shapes and structures in multicellular organisms, and is 

 proceeding by the evolution, in the higher of them, of 

 an immense power of varying in response to stimulation 

 from the environment, by means of which they are 

 placed in closer correspondence with it. Contempora- 



