38 THE PHYSIOLOGY OF PROTEIN METABOLISM 



Protamine given alone would even seem to exert a certain protein 

 sparing power. 



The polypeptide group does not appear to be of paramount import- 

 ance in spite of Abderhalden's earlier work ; in an experiment carried 

 out by Abderhalden and Oppler (20) a dog was kept alive for thirty- 

 eight days, during which time the nitrogen supply was in the form of 

 an abiuret digest mixture consisting almost solely of amino acids. 

 Abderhalden and Rona (21) fed a young dog for three weeks on 

 completely digested meat biuret free and found not only a re- 

 tention of nitrogen, which was to be expected under normal con- 

 ditions with the growing animal, but a distinct increase of weight. 

 Abderhalden (2) was also able to keep a bitch in nitrogenous equilibrium 

 with fully digested meat during lactation. Even more astonishing 

 was the result of an experiment carried out by Abderhalden and 

 London (28) on a dog with an Eck fistula, as not only did they get 

 their animal into a state of nitrogenous equilibrium, but it retained a 

 certain amount of nitrogen, although the protein part of the diet 

 consisted wholly of fully digested meat. The body weight of the 

 animal slowly sank, however, during the course of the experiment. 

 Abderhalden and London used this experiment as a weighty piece of 

 evidence in favour of the synthesis of the protein digestion products 

 taking place immediately after absorption. They also stated in con- 

 clusion that the liver must not be considered as an organ of absolute 

 importance in protein synthesis. 



Henriques (185) returned to the question of the difference in nutri- 

 tive value which exists between ferment and acid hydrolytic products. 

 He found, although unfortunately the experiments were again carried 

 out on rats, that ferment digestion products (trypsin and erepsin) 

 heated with 20 per cent, sulphuric acid for six hours in a boiling water 

 bath could keep the animals in nitrogenous equilibrium, and even bring 

 about a retention of nitrogen, yet the same products heated in the same 

 way with the acid for seventeen hours utterly failed to produce this 

 sparing effect. The only difference which he could detect between the 

 two preparations was that after the six hours' acid hydrolysis the 

 tryptophane reaction could be obtained, but that in the seventeen hours 

 specimen it had disappeared. In this connexion the work of Miss 

 Willcock and Hopkins (199) is of interest (see p. 73). 



Recently Abderhalden returned to the question why acid hydro- 

 lytic products failed and ferment digest products succeeded in bringing 

 about nitrogenous equilibrium. As just mentioned, Henriques found 

 that if the acid hydrolysis were not too prolonged, if the tryptophane 



