NATURE OF PROTOPLASMIC RESPIRATION. 345 



In the third place a mass of evidence shows that substances 

 outside the body simply dissolved in water, break up at a very 

 slow rate, but into the same compounds in many instances as ap- 

 pear at a rapid rate in protoplasm. 



These facts may be summarized in the general statement : 

 Living matter does not determine the character of the transfor- 

 mation of the foods ; it only determines the rate of transformation. 



This conclusion at once makes clear that living matter is 

 to-day originating spontaneously from the foods just as it always 

 has. The transformation goes on now very rapidly owing to 

 catalyzers in protoplasm, whereas originally the transformation 

 probably went on slowly until some of the products of the reac 

 tion were produced which acted as catalyzers for this or thJ: 

 phase. What we call living matter is of importance in the proc- 

 ess only because it contains from the outset these end-product 

 catalyzers, formed from the previous reaction. The whole proc- 

 ess is, I conceive, as follows : 



The carbon constituents of the foods spontaneously decom- 

 pose. By this decomposition particles in a nascent state are 

 formed. Upon Nef's hypothesis these would be particles with 

 bivalent carbon. Whatever their nature these nascent particles 

 either act on the water, oxidizing themselves to aldehydes or 

 ketones and setting free hydrogen and in this manner causing 

 protoplasmic respiration ; or they combine with each other to 

 form the various constituents of protoplasm and thus cause 

 growth. What they combine with depends on what substance 

 is near when they become nascent. If it is ammonia amids, 

 amino-acids and other nitrogen compounds are formed ; if an- 

 other carbon compound, the carbon chains are built up and the 

 complex substances which make up protoplasm. The whole 

 process is due to a spontaneous dissociation of the food mole- 

 cules and is not due to any vital energy. Some of the end-prod- 

 ucts of this spontaneous rearrangement act as ferments, that is, 

 as accelerators of some phase of the reaction, or they may act as 

 negative catalyzers delaying some phase. Examples of such 

 processes are well known in chemical reactions. In exactly 

 what manner they accelerate or delay the reaction is not certain. 



The bearings of this conclusion upon many problems of biol- 

 ogy, and particularly upon the problem of differentiation in 



