SOME NEW VIEW POINTS IN NUTRITION 393 



place whereby cell protein is broken down into its component parts, 

 while at the same time a synthesis of protein may be occurring from 

 other amino-aeids brought by blood or lymph with a possible utilization 

 of some of the fragments liberated by the autolysis. In other words, 

 our conception of nutritional changes to-day embodies the hypothesis 

 of a synthesis of protein throughout the body; that it is a function of 

 every living cell, " each one for itself, and that the material out of 

 which all proteins in the body are made is not protein in any form, but 

 the fragments derived from proteins by hydrolysis, probably the amino- 

 acids, which in different combinations and different proportions are 

 found in all proteins, and into which they are all resolved by the proc- 

 esses, autolytic or digestive, which can be carried out in every cell of 

 the body" (Leathes). 



Here, we have presented several points of view which are radically 

 unlike the old-time traditions concerning nutrition. Objects and 

 methods are both out of harmony with the long prevalent conception 

 of the plan of the living organism in which oxidation was confessedly 

 the ruling power. Profound and progressive hydrolytic cleavage is now 

 seen to be the purpose of digestion, as well as of the autolytic processes 

 which are associated with all the tissues and organs of the body; a 

 cleavage which proceeds until the complex protein is split apart into 

 its simplest chemical groups or components. In this process there is no 

 sign of direct oxidation, but hydrolysis appears in the foreground, and 

 by this means the rock protein is broken asunder into small fragments 

 of definite shape, each of which can be used in the construction of fresh 

 protein. Especially noteworthy is the harmony of action between the 

 enzymes of the digestive tract and those of the living tissues of the body. 

 Both have the same object in view ; there may be differences in the rate 

 of action, but in the end essentially the same simple fragments result. 

 Again, what a suggestion of broad constructive power in the cells of the 

 animal body; what a powerful synthetical process that by which the 

 animal cell manufactures the most complex substance of its body pro- 

 toplasm ! For years the chlorophyll-containing cell of the plant world 

 enjoyed the distinction of being the main laboratory in nature for the 

 synthesis of organic compounds. The animal body could transform 

 and modify, it could even accomplish a mild form of synthesis, such as 

 a combination of two large molecules to form a still larger conjugate, 

 but anything like a true synthesis, i. e., the formation of a well-defined 

 complex, such as protein, out of simple amino-acids was far beyond our 

 imagination, until now accumulated facts seem to open up a new point 

 of view. 



Are we really warranted in accepting this modern conception of 

 protein synthesis in the animal body ? Are the facts available sufficient 

 to substantiate the claim advanced? Physiologists quickly recognized 



