PROTEIN METABOLISM 85 



in the later stages the greatly diminished uniform 

 protein metabolism was that of the organized or tissue 

 proteins. 



In his theory Voit assigned to the cells the function 

 of utilizing proteins, the older view that metabolism 

 took place in the blood having been discarded. From 

 the fluids bathing the tissues food or circulating pro- 

 tein is drawn within the cells and there transformed. 

 On the other hand, a certain small amount of tissue 

 protein is constantly dying and is replaced by circulat- 

 ing protein, thus becoming eventually living proto- 

 plasm. "The tissue-elements constitute an apparatus 

 of a relatively stable nature, which has the power of 

 taking proteins from the fluids washing the tissues and 

 appropriating them, while their own proteins, the tissue 

 proteins, are ordinarily catabolized to only a small ex- 

 tent, about 1 per cent daily." (Voit.) "By an in- 

 creased supply of proteins the activity of the cells and 

 their ability to decompose nutritive proteins are also 

 increased to a certain degree. When nitrogenous 

 equilibrium is obtained after an increased supply of 

 proteins, it indicates that the decomposing power of 

 the cells for proteins has increased so that the same 

 quantity of proteins is metabolized as is supplied to the 

 body. If the protein metabolism is decreased by the 

 simultaneous administration of other non-nitrogenous 

 foods, a part of the circulating proteins may have time 

 to become fixed and organized by the tissues, and in 

 this way the flesh of the body increases. During 

 starvation or with a lack of protein in the food the 



