26 IMMUNE SERA. 



with their immune body in other words, whose 

 haptophore group had been satisfied were unable 

 to excite the production of any haemolysin when 

 injected into animals. 



All of the specific relations which we have seen 

 exist between toxin and antitoxin, Ehrlich and 

 Morgenroth in their experiments above noted 

 found to exist also between immune body and 

 the specific blood-cell. The immune body must 

 therefore possess a haptophore group which fits 

 exactly to certain receptors or side-chains of the 

 red cells, just as the anti-body according to the 

 side-chain theory possesses a group that fits ex- 

 actly into the specific combining group i.e., hap- 

 tophore group of the toxin or toxoid used for ex- 

 citing the immunity. 



If, for example, we produce a haemolytic serum 

 specific for red cells of a rabbit by injecting an 

 animal with these cells, the haptophore groups of 

 this serum, i.e., the free side-chains thrust off, must 

 possess specific combining relations with the red 

 cells of rabbits. That such is the case in the hae- 

 molytic immune serum we saw from the experi- 

 ments of Ehrlich and Morgenroth. 



The Theory Applied to the Production of Other Anti- 

 bodies. In consequence of all this, Ehrlich wid- 

 ened the application of his side-chain theory so as 

 to include not only the production of antitoxin 

 but also the production of bactericidal, haemolytic, 

 and other immune bodies. He expressed this 



