CHAPTER XI 



MEDIUM 



IN the former chapters we have already stated how 

 adaptation, selection, and heredity were one and 

 the same thing, studied separately for greater 

 clearness ; but provided we do not forget that they 

 are different periods of one phenomenon ; that is, 

 selection is the same adaptation, but journeying 

 towards a fixed end ; heredity is the repetition of 

 adaptation, which cannot vary, because it is the 

 reflex of the universal mechanics, and heredity 

 repeats the same organisation by the immutability 

 of the laws of Nature. Adaptation and heredity 

 repeat one and the same organisation, at different 

 periods, just as selection defines this organisation 

 by a fixed meaning. 



On studying the medium separately we make 

 another artificial division, for the mutual depend- 

 ence that exists between the medium (universal 

 mechanics) and organisation (adaptation, selection, 

 arid heredity) is very plain. And we come to the 



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