MECHANISM OF PROTEIN HYDROLYSIS AND IMMUNIZATION 31 



depicted as tangible structures, some of them resembling hungry 

 polywogs biting eagerly at inviting bits of protruding protoplasm 

 of just the right size to make a mouthful proved altogether 

 alluring. A glance at such a diagram enables one to form a clear 

 mental picture of the relations of receptive cells and complement 

 and immune bodies in happy disregard of all possible chemical 

 complexities. 



In due course numerous workers proved the universality of 

 application of the principles of the formation of the antibodies 

 through the introduction of toxic agents into the organism. We 

 learned of antitoxins, anti ferments, cytotoxins, agglutinins, pre- 

 cipitins, and opsonins in the normal blood serum or developed spe- 

 cifically in response to the invasion of toxins ; then it appeared 

 that there may be anticytotoxins, anti ferments, etc.; in bewilder- 

 ing profusion. And it was at least suggested that were our 

 means of investigations sufficiently delicate we should find anti- 

 antibodies in unending series, each new antidote becoming in 

 turn a toxin and requiring an antidote ; and the orgainc labora- 

 tory proving quite capable of developing series of such responsive 

 mechanism ad infinitum. 



To add to the confusion, different workers gave different names 

 to the substances revealed in the course of their investigations ; 

 and in many cases they were talking of the same thing in terms 

 of a different nomenclature. Thus the ferment that Ehrlich calls 

 addiment was named by others alexine, by still others cytase 

 and yet again complement the last name being the one ulti- 

 mately adopted by most authorities. 



In the same way the immune bodies came to be known as 

 amboceptor, copula, desmon, hilfskorper, zwischenkorper, fixa- 

 teur substance, sensibilisatrice, etc. And it became a matter 

 for dispute as to whether agglutinins, precipitins, and opsonins 

 are identical one with another, and also as to the relations that 

 these substances recognized only by their effects bear to the 

 various hemolysins, bactericides, and bacteriolysins. 



Out of the confusion, however, emerged pretty clearly the 

 conception that there are two types of so-called bodies or chem- 

 icals involved in the immunizing process. One of these is a 

 ferment-like substance which is thermolabile, its action being 

 prevented by heating to a temperature of about sixty degrees 

 centigrade ; this substance being conveniently referred to as the 

 complement. Joined with the complement in the immunizing 

 process is a thermostable substance which may be comprehen- 

 sively termed the immune body which apparently includes agglu- 

 tinins, opsonins, and bacteriolysins (whether or not these are 

 identical). The thermolabile complement is non-specific, in the 

 sense that the same complement may unite with many types of 



