THE CHEMICAL BASIS OF LIFE 



There being no evidence to justify us in assum- 

 ing that life processes are due, primarily, either 

 to specific details of physical structure or to ex- 

 treme complications of molecular structure, we 

 find ourselves driven to the conclusion that life 

 processes must be due to some comparatively 

 simple principle of chemistry which has not yet 

 been discovered. To find a clue to this we must 

 investigate the chemical structure of proteins, 

 because protoplasmic materials which are prin- 

 cipally of protein constitution appear to consitute 

 the basis of all life processes. Fats and carbo- 

 hydrates, although formed during protein metab- 

 olism, are evidently nothing more than by-prod- 

 ucts which may be useful at times for fuel or 

 skeletal support and may by their presence exert 

 the most profound effects upon the behavior of 

 the surrounding protoplasmic materials but are 

 not chemically constituted in such a manner that 

 they can grow or reproduce. 



All proteins decompose hydrolytically upon 

 prolonged boiling with hydrochloric or sulphuric 

 acid or with alkalies, upon treatment with super- 

 heated steam, or upon treatment with certain 

 enzymes such as pepsin or trypsin, and yield as 

 their principal cleavage products a mixture of 



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