104 THE PHYSIOLOGY OF PROTEIN METABOLISM 



put of both creatinine (and creatine) and purine indicated the possi- 

 bility of a certain retention of muscle tissue having taken place, it 

 may be inferred that the partial splitting of the protein molecule, 

 which led to the liberation of these substances, could not have pro- 

 ceeded so far as to set free the sulphur. On the other hand, it must 

 be remembered that, according to Ehrstrom, Falta and others, the 

 sulphur-containing part of the molecule must be looked on as the 

 labile part. It is possible that all the sulphur was liberated from the 

 muscle protein, and that the balance of nitrogen excreted was made 

 up from other sources. Until, however, reliable analyses of tissues are 

 available it is impossible to come to any definite conclusion. Voit 

 and Korkunoff hold that the nitrogen excreted in hunger does not 

 come from actual tissue protein alone, but may also originate from 

 the extractives of the organs. They found that the tissue mass of a 

 goose after five days' starvation contained 15*39 per cent, nitrogen. 

 Of this 12-55 per cent. (81.55 per cent, of the total nitrogen) was in 

 the form of protein, and 2*84 per cent. (18-45 P er cent - f tne total 

 nitrogen) was of extractive nature. 



The Influence of Non-nitrogenous Substances on the Rate of the 



Protein Breakdown. 



The fact must not be lost sight of that the amount of nitrogen 

 liberated protein utilized directly depends on the supply of nitro- 

 gen-free food, like fat. So long as there is a sufficiency of fat present 

 in the organism the nitrogen output slowly falls, but as soon as the 

 fat store is all utilized, there is a rise in the output of nitrogen. 

 This fact has been clearly demonstrated by a large number of workers, 

 by C. Voit (VII), Schondorff(359), Rubner (341), E. Voit (409) and 

 others. It has also been clearly demonstrated that an animal with 

 large stores of fat will resist starvation better than one which is thin. 

 Schulz and his pupils (365), on the other hand, hold that the premortal 

 rise in the output of nitrogen is not due to the lack of fat, or other 

 nitrogen-free food material, but to a general breakdown of the cells 

 themselves as the result of injury due to the hunger. E. Voit denies 

 this. He holds that death in starvation arises not from the death of 

 the total cell mass of the body, but from nutritional disturbances of 

 essential organs. Reicher (336) also is inclined to accept this view. 

 This worker was never able to detect any evidence of necrosis. He 



