THE BEGINNINGS OF LIFE. 427 



stituents of the blood or of food, coming in contact 

 with such changing particles that consequently the 

 animal metamorphosis is itself a main cause of the 

 alterations that the food undergoes, and a determining 

 condition of the nutritive process.' 



The breadth and suggestiveness of these views of 

 Liebig are most striking, and we venture to hope 

 that they may be considered to derive additional sup- 

 port from our own experiments all of which tend 

 to show the essential similarity of the influences that 

 occasion both the c genesis ' and the c growth ' of living 

 matter. Chemical affinities, variously modified by 

 physical agencies, are the causes of those fermentations 

 which lead to the production of living matter; and 

 chemical affinities similarly modified, are again all 

 powerful in continuing the growth of the matter thus 

 initiated. Nutritive processes are closely allied to 

 fermentative processes, and both sets of phenomena 

 are due to common causes. In other words, the same 

 forces which are operative in the production of the 

 subsequent units of living matter are potential in the 

 initiation of the first unit. The occurrence of living 

 matter is, like the formation of crystalline matter, 

 the result of inherent molecular affinities and of im- 

 mutable natural laws. 



