HMMOLYSINS. 27 



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 



(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 

 firm union with a definite part of the living organ- 

 ism, the receptor. This is not the case with alka- 

 loids, e.g., morphin, strychnin, etc., which accord- 

 ing to Ehrlich enter into a loose union, a kind of 

 solid solution with the cells. It is for this reason 

 that we are unable to produce any anti-bodies in 

 the blood serum against these poisons. Ehrlich 

 says further that all of the substances taking part 

 in the production of immunity, including of course 

 complement and immune body, have certain defi- 

 nite affinities for each other, and in order to act 

 they must fit stereochemically to each other. 



As we have already seen, we are able by means 

 of the injection of a variety of substances or cells 

 to produce a similar variety of immune bodies in 

 the serum. Thus we can immunize a rabbit so 

 that its serum will possess specific haemolytic 

 bodies against the red cells of guinea-pigs, goats, 



