40 THE PHYSIOLOGY OF PROTEIN METABOLISM 



the extremely interesting experiments of Abderhalden and Olinger 

 (29) the nature and constitution of the whole digest evidently plays 

 its part. They starved a dog and within seventeen days the weight 

 of the animal fell from 8820 grm. to 7120 grm. They then gave the 

 animal 3-03 grm. of nitrogen in the form of fully digested caseinogen, 

 but after six days of this diet there was no increase of the animal's 

 weight. The nitrogen intake was increased to 3 '99 grm. of the same 

 digest, but still without effect. Then the caseinogen digestion pro- 

 ducts were replaced by an equal amount (3 '99 grm.) of nitrogen from 

 fully digested horse flesh, and after twenty-one days on this diet the 

 weight of the animal rose from 7000 grm. to 8400 grm. That this 

 was not due to mere storage of unutilized nitrogenous material was 

 clearly demonstrated by the fact that when the animal was starved 

 again the daily loss of nitrogen was quite similar in amount to that 

 which took place in the first instance without any previous protein 

 storage. If this had been a mere accumulation of nitrogenous products 

 in the tissues a great loss of nitrogen during the first days of starvation 

 might have been expected. In all these experiments the diet was 

 made up of a mixture of fat and carbohydrate in addition to the pro- 

 tein digest. Abderhalden, Messner and Windrath (48), however, in 

 contradistinction to all previous experience, state that they managed to 

 keep an animal in nitrogenous equilibrium with a diet of digestion 

 products and fat minus carbohydrates. Of course the explanation here 

 may lie in the fact that the protein was given in such amount that it 

 (or possibly the fat) was partially converted into carbohydrate. And 

 later Abderhalden and Suwa (37) maintained that they were able to 

 keep a dog in nitrogen equilibrium and to obtain an increase of 

 weight on a protein digestion product alone. Their experiments are, 

 however, very unsatisfactory, as great trouble was experienced in the 

 feeding of the dog with the result that the nitrogen intake was not 

 constant. 



As the fact had now been abundantly proved that digestion pro- 

 ducts could not only maintain nitrogenous equilibrium but even lead 

 to storage of protein in the lower animals, it was of interest to see 

 whether the same result could be obtained in man. Abderhalden, 

 Frank and Schittenhelm (49) were fortunate enough to obtain a human 

 subject, a boy of twelve, with a stricture of the oesophagus and on whom 

 gastrotomy had been performed. The experimental material used 

 was flesh completely digested by trypsin and erepsin. The result of 

 feeding per rectum for fifteen days with these digestion products as 

 the main source of protein was that nitrogenous equilibrium was at- 



