BACTERIOLYSIS AND ALLIED PHENOMENA l6l 



dissolving doses of the antiserum. A control test showed that 

 normal goat serum was without action. 



Theoretically, two anti-amboceptors are possible : one which 

 will combine with the cytophile group of the amboceptor, and one 

 which will seize on the complementophile. In his earlier studies 

 Ehrlich thought that the former was that actually produced when 

 immune sera are injected into animals of another species. He 

 later altered his opinion, and now holds that the substance 

 actually formed is an antibody to the complementophile hapto- 

 phore of the amboceptor. He was led to this conclusion by a 

 discovery of Bordet's, which was adduced as evidence against the 

 amboceptor theory, but which was ingeniously adapted to its 

 defence by Ehrlich. The discovery was as follows : Normal 

 rabbit serum when injected into a guinea-pig leads to the production 

 of an anti-antibody, which neutralizes the haemolysin formed by 



FIG. 41. THE COMPLEMENTOPHILE HAPTOPHORE GROUPS OF AN AMBO- 

 CEPTOR "BLOCKED" BY ANTIAMBOCEPTOR (a, a}. 



immunizing with ox blood. This, of course, is readily explicable 

 if normal rabbit serum contained an amboceptor for ox corpuscles, 

 but this is not the case. Ehrlich argued as follows : An anti- 

 amboceptor is obviously formed, but the normal rabbit serum 

 injected contains no amboceptor i.e., no cytophile groups ; hence 

 the ant -amboceptors produced must be anticomplementophile. 

 For this to happen it is necessary that this normal rabbit serum 

 must contain complementophile groups, and this is obviously the 

 case, since other amboceptors, each with a complementophile 

 group, are present. Therefore, on the assumption that these 

 groups are similar, even when they occur in different amboceptors, 

 the case is clear. But are these complementophile groups similar ? 

 Does not this contradict Ehrlich's views on the multiplicity of 

 complements ? To avoid this difficulty, Ehrlich falls back on his 

 polyceptor theory. All or most amboceptors are really poly- 

 ceptors, differing only or mainly in their cytophile groups, and 

 possessing numerous complementophile groups, which are similar 

 or identical in different cases in the same species. But if this 



ii 



