PROTEIN REQUIREMENTS 79 



brought about some decrease in the amount of total nitrogen excreted. 

 My own results rather suggest that division produces a slight increase 

 in the output of nitrogen. In this connexion the work of Leathes (247) 

 is interesting. He showed that there was a well-marked tide in the 

 output of total nitrogen ; in the twenty-four hours the highest output 

 was between ten p.m. and four a.m. and the lowest output between four 

 a.m. and ten a.m. Osterberg and Wolf (316) also observed the same 

 diurnal and nocturnal variations. 



Storage of Protein. 



Another question of great importance is whether protein is ever 

 stored in the body in the same way, or approximately the same way, 

 as carbohydrate and fat. No one doubts now that excess of carbo- 

 hydrate from the food is stored in the liver and other tissues, princi- 

 pally the muscles, as glycogen, and that the fat is stored as fat. Both 

 these stores can give up their supplies with great readiness when re- 

 quired. But the question of protein storage has not yet been definitely 

 settled. There is no doubt that the body requires daily a certain 

 supply of protein material to repair tissue waste, but if there be no 

 supply from without can the body for a short period, as is the case 

 with carbohydrates, or for a longer period, as in the case of the fats, 

 draw this necessary protein from stored material, or must it break 

 down its protein tissues ? If the demand for endogenous protein be 

 prolonged, as in the case of a fast or in protein starvation, then the 

 protein for the most part comes from the breakdown of protein tissue. 

 Voit and Chossat have both shown that there is a general wasting of 

 certain protein tissues like muscle, during a fast. But if the depriva- 

 tion of the supply of protein from without be only for a short period 

 a day or two at most the answer is not so clear. Unfortunately the 

 amount of experimental evidence in this field is not large. Pfltiger (329) 

 as the result of observations, which he made during his well-known ex- 

 periments on glycogen formation and storage, came to the conclusion 

 that the liver must be regarded as a storehouse for protein. He held 

 that the hepatic cells not only manufactured this reserve protein from 

 the food proteins, but also that this protein, just as is the case with 

 glycogen, was held in reserve in the liver to meet urgent demands from 

 the active tissues. Schreuer (361) by the study of the respiratory 

 quotient, also came to the conclusion that there was a certain limited 



