MECHANISM OF PROTEIN HYDROLYSIS AND IMMUNIZATION 65 



directly through the parenteral presence of a protoplasmic body. 

 And the question at once arises as to the source of this anti- 

 toxin. Is the leucocyte here as before the agent that guards 

 the body from the insidious attack? 



The attempt to answer this question has proved more puzzling, 

 if possible, than the attempt to localize the mechanisms that an- 

 tagonize and give immunity to the bodies of the bacteria them- 

 selves. Most workers in the field leave the question quite unan- 

 swered. It suffices for them that the antitoxin is produced some- 

 where in the body, and that it ultimately permeates the serum 

 of the blood. But it is obvious that a satisfactory theory of 

 immunity must give us a far more definite answer. 



In the opinion of the present writer, there are data at hand 

 that enable one to answer the question with a fair degree of 

 definiteness. It must be admitted, however, that these data do 

 not include unequivocal and demonstrative experiments, such 

 for example as the discovery of the antitoxin in some specific 

 tissues before it appeared in the blood serum. We must be 

 content with indirect evidence. This, however, is to say the 

 least highly suggestive, and its findings are full of interest. In 

 my opinion, they justify the belief that the chief agents in the 

 formation of antitoxins are the red blood corpuscles ; their efforts 

 being supplemented, however, on occasion, by the work of the 

 leucocytes on one hand and by the various body tissues on the 

 other. 



The evidence is based very largely on experiments undertaken 

 for a quite different purpose and having to do with the hydrolysis 

 and synthesis of proteids. In particular the work of Emil Fischer 

 and his pupils has given the clue, although, so far as I am aware, 

 no one had attempted to interpret or follow it up until this was 

 done in my original presentation of the Proteomorphic theory in 

 American Medicine of October and November, 1914. 



To gain an inkling of the import of this work, in the present 

 connection, we must very briefly summarize some of its impor- 

 tant findings as to proteolysis. The most significant of these ex- 

 periments, from the present standpoint, are those in which Abder- 

 halden has tested the capacity of enzymes excerpted from differ- 

 ent bodily tissues to hydrolyze various synthetic polypeptids. The 

 polypeptids were so named by Fischer to indicate their relation- 

 ship with peptones. It is believed that the peptones (as hydro- 

 lyzed from protein through the medium of proteoses) consist 

 of a chemical aggregation of various polypeptids. Stated other- 

 wise, polypeptids would result from the cleavage of peptones; 

 although in point of fact those experimented with were syn- 

 thesized in the laboratory by the combination of various amino- 

 acids. 



