HOW IS ORGANIC EVOLUTION CAUSED 409 



the hypothesis of evolution, but he does something towards 

 elucidating the process of evolution. His reasonings show 

 us an unconscious mingling of the belief in a supernaturally- 

 impressed tendency to develop, with the belief in a develop- 

 ment arisiiig from the changing 'incidence of conditions. 

 Probably had he pursued the inquiry further, this last belief 

 would have grown at the expense of the first. La- 



marck, in elaborating this general conception, has given 

 greater precision to both its truth and its error. Asserting 

 the same imaginary factors and the same real factors, he has 

 traced out their supposed actions in detail ; and has, in con- 

 sequence, committed himself to a greater number of un- 

 tenable positions. But while, in trying to reconcile the 

 facts with a theory which is only an adumbration of the 

 truth, he laid himself open to the criticisms of his con- 

 temporaries ; he proved himself profounder than his con- 

 temporaries, by seeing that evolution, however caused, has 

 been going on. If they were wise in not indorsing a theory 

 which fails to account for a great part of the facts ; they 

 were unwise in ignoring that degree of congruity with the 

 facts, which shows the theory to contain some fundamental 

 verity. 



Leaving out, however, the imaginary factors of evolution 

 which these speculations allege, and looking only at the one 

 actual factor which Dr Darwin and Lamarck assign as 

 accounting for some of the phenomena ; it is manifest from 

 our present stand-point, that this, so far as it is a cause of 

 evolution, is a proximate cause and not an ultimate cause. 

 To say that functional adaptation to conditions, produces 

 either evolution in general, or the irregularities of evolution, 

 is to raise the further question why is there a functional 

 adaptation to conditions ? why do use and disuse generate 

 appropriate changes of structure ? Neither this nor any other 

 interpretation of biologic evolution which rests simply on the 

 basis of biologic induction, is an ultimate interpretation. The 

 biologic induction must itself be interpreted. Only when 

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