THEORIES OF EVOLUTION 111 



regards it as the only philosophy which can do 

 justice to all of the facts. ^ Unfortunately we can- 

 not all agree that the tendency of life processes 

 "is something elemental," or even that a vitalistic 

 concept is necessary, but it is obvious that we may 

 concur with the vitalists in the opinion that biology 

 can only inquire into the manifestations of life as 

 they stand before us, on a physico-chemical basis, 

 whatever may be their ultimate cause. 



With this precept as an initial article of faith 

 we may eliminate from consideration all of the 

 vitalistic theories of life and evolution. Whether 

 an unknown principle is at the foundation of vital 

 processes or whether these processes are not, rather, 

 merely the results of incomprehensible intricacy 

 of organization, we cannot say, but we may be in- 

 creasingly certain as biology progresses that every 

 vital process is the immediate outcome of char- 

 acteristic physico-chemical phenomena and that 

 it is governed by physico-chemical laws. To John- 

 stone this attitude on the part of biologists means 

 that the "mechanistic conception of life is only the 

 result of the extension to biology of methods of 

 investigation, and not a legitimate conclusion from 

 their results.'' ^ To the biologist it means that only 

 one course is plain, viz., the extension of these 

 methods to the greatest possible degree until one 

 of two ends shall be reached. They may trip him 



' Geschichte des Lamarckismiis, p. 18, 1909. ' Op. cit., p. 121. 



