66 IMMUNE SERA 



according to the side-chain theory possesses a 

 group that fits exactly into the specific combining 

 group i.e., haptophore group of the toxin or 

 toxoid used for exciting 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 haemo- 

 lytic immune serum we saw from the experiments 

 of Ehrlich and Morgenroth. 



In consequence of all this, Ehrlich widened 

 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 

 somewhat as follows: // any substance, be it toxin, 

 ferment, constituent of a bacterial or animal cell, or 

 of animal fluid, possess the power by means of a 

 fitting haptophore group to combine with side chains 

 (receptors) of the living organism, the possibility for 

 the overproduction and throwing off of these recep- 

 tors is given, i.e., the possibility to produce a cor- 

 responding anti-body. 



Specific anti-bodies in the serum as a result of 

 immunizing processes can only be produced, there- 

 fore, by substances which possess a haptophore 

 group and which, in consequence, are able to form a 



