PHILOSOPHICAL REFLECTIONS 241 



and the genesis of tissues (not a hundred years 

 old) at one time seemed to be the key to an 

 explanation oi ital phenomena. Then came 

 a time, not so long ago, when physical methods 

 of investigation were in vogue, and it was 

 thought that many phenomena were merely 

 physical, requiring for their interpretation 

 measurement, weighing, and graphic registra- 

 tion. At the present time, considerations of 

 chemical phenomena are prevalent in the 

 minds of physiologists. The structure of the 

 complex proteins and other bodies is being 

 investigated ; syntheses of many organic sub- 

 stances have been accomplished ; even elemen- 

 tary protein-like bodies have been formed, 

 and the formation of complicated proteins is 

 within sight. Chemical phenomena in the 

 great processes of respiration, nutrition, and 

 digestion are being thoroughly investigated. 

 The agency of ferments is now recognized as 

 all-important not only in digestion but in 

 nutrition. Osmotic phenomena in living 

 matter have received recently much attention, 

 and some of the visions of advanced physicists 

 as to the constitution of matter have been 

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