MECHANISM OF PROTEIN HYDROLYSIS AND IMMUNIZATION 69 



NEW EXPERIMENTAL EVIDENCE 



The above exposition of the theory of proteolytic activities 

 of the red corpuscles is reproduced precisely as it was presented 

 in the original exposition of the Proteomorphic Theory in Amer- 

 ican Medicine of October, 1914. It will be obvious that the 

 hitherto unsuspected function thus ascribed to the red corpuscles 

 matches in importance, if its validity is demonstrated, the function 

 of carrying oxygen to the tissues each being absolutely essen- 

 tial to the life of the individual. The subject having such funda- 

 mental importance, then, it will be of interest to cite here a 

 series of experiments made about two years later, which give 

 strong support to the theory of erythrocytic polypeptid digestion. 



The experiments in question have to do with the distribution 

 of the residual nitrogen between the blood cells and the plasms, 

 originally published in the Biochemische Zeitschrift, as reported 

 in Physiological Abstracts (published by the Physiological Society 

 of Great Britain and Ireland with the co-operation of the Amer- 

 ican Physiological Society) in the tissue of October, 1916. The 

 experimenter was Dr. Ivar Bang. The abstract is as follows: 



"The residual and urea nitrogen in the blood and plasma were 

 determined in well-nourished rabbits before and after a seven- 

 day fast during which no water was given. The amino-acid frac- 

 tion was represented by the difference between the residual and 

 urea nitrogen. In accordance with the findings of earlier experi- 

 ments, an increase in residual nitrogen occurred after the fast 

 which concerned the urea fraction only. Before the fast urea 

 was equally distributed between the cells and the plasma, while 

 the cells were richer than the plasma in amino-acid; these rela- 

 tions persisted after the fast. 



"After the introduction of a solution containing two to three 

 grams of glycine into the bowel, there was an increase in the 

 residual nitrogen of the blood, which affected the amino-acid frac- 

 tion almost exclusively. The increase was confined to the plasma, 

 and hence the amino-acid content of the blood cells is probably 

 formed in the cells themselves." 



It will be observed that "blood cells" as a whole are here 

 referred to, with no specific reference to the red cells. But the 

 fact that the latter are about one thousand times as numerous as 

 the leucocytes, constituting the main bulk of the formed matter 

 of blood, makes it highly probable that the amino-acids in ques- 

 tion were contained very largely at any rate in the eryphrocytes. 



Such experimental proof of the completion of protein hydroly- 

 sis in the corpuscles is interesting from a theoretical standpoint, 



