CERTAIN DERIVATIVES OF THE PROTEIDS. 321 



of carbon.* The composition of the deuterogelatose, on the 

 other hand, is seen to be essentially identical with that of the 

 gelatin from which it was derived, thus agreeing with the ob- 

 servations previously recorded by Chittenden and Solley f on 

 the composition of the gelatoses formed by gastric and pan- 

 creatic digestion. 



The protogelatose (protogelatose /") tested intravenously 

 was a specimen prepared by pepsin-proteolysis of a purified 

 commercial gelatin, J and had the following composition : 



C 49.98, H 6.78, N 17.86, S 0.52, O 24.86, Ash 1.98. 



ADDENDUM. 



Since this work was completed two exceedingly interesting 

 and important papers on antipeptone have appeared from 

 Kossel's laboratory, which have a direct bearing upon the 

 purity of antipeptone formed from blood-fibrin by digestion 

 with an alkaline pancreatic extract. Kutscher's results tend to 

 show that ordinary antipeptone formed from blood-fibrin by 

 pancreatic digestion and purified by the methods ordinarily 

 made use of contains a large proportion of impurities composed 

 in great part of the nitrogenous bases arginin, histidin, and a 

 new body as yet undescribed, together with aspartic acid and 

 some leucin and tyrosin. Assuming this to be true of all 

 antipeptones formed from native proteids by direct digestion 

 with pancreatic juice, it follows that the products of this kind 

 hitherto tested physiologically are open to the suspicion of 

 being unsuitable for experiments of this nature. How far 

 the same criticism will apply to the antipeptone employed by 

 us in the present experiments is uncertain. It would seem, 

 however, that the antipeptone prepared from antialbumid 

 might perhaps be free from this objection or at least contain 

 a far smaller amount of impurity, since in the hydrolysis and 



* Chittenden, Digestive Proteolysis, New Haven, 1895, p. 71. 

 t Chittenden and Solley, Journal of Physiology, 1891, xii, p. 23. 

 t Chittenden and Solley, loc. cit., p. 28. 



Kutscher, Zeitschr. f . physiol. Chem., 1898, xxv, p. 195 ; Kutscher, Ibid., 

 1898, xxvi, p. 110. 



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