30 DOCTRINE OF EVOLUTION 



It is true that even at the present time some biologists 

 are reluctant to accept the thoroughgoing mechanical 

 interpretation of organic phenomena, partly because 

 these are so complex that their ultimate constituents 

 cannot be discerned, but more often on account of the 

 apparently purposeful nature of biological processes. 

 Some, indeed, have gone so far as to postulate some- 

 thing like consciousness which controls and directs the 

 formation of protoplasm, and the exercise of its dis- 

 tinctive properties in the way of growth, reproduction, 

 and embryonic development into the adapted adult. 

 But the fact remains that wherever analysis has been 

 possible the constituent elements of an organic process 

 prove to be physical and chemical. Protoplasm differs 

 from inorganic materials only in its complexity and 

 in the properties which seem to owe their existence 

 to this complexity. As Huxley points out, it is no more 

 justifiable to postulate the existence of a vitalistic 

 principle in protoplasm than it would be to set up an 

 aquosity" to account for the properties of water, or a 

 saltness" for the qualities of a certain combina- 

 tion of sodium and chlorine. We may not know how 

 the elements produce the properties of the compound, 

 but we do know that such properties are the invariable 

 products of their respective constituents in combina- 

 tion. As far as the evidence goes, it tells strongly and 

 invariably in favor of the mechanistic interpretation. 



Under the present limitations, it is impossible to give 

 this subject the further discussion it deserves. It is 

 not our purpose to review the origin of life in times 

 past, and the origin of living matter from inorganic 

 constituents, though the subject is one of the most 



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