70 IMMUNE SERA 



alkaloids, e.g., morphine, strychnine, etc., which 

 according 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 

 definite 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, 

 chickens, and oxen and specific bactericidal 

 bodies against cholera and typhoid bacilli, etc., 

 and as we shall see, still other groups of anti- 

 bodies. 



Multiplicity of Complements. Under these cir- 

 cumstances an important question presents itself: 

 Is there in normal serum one single complement 

 which completes the action of all these various 

 immune bodies, one, for example, which in the 

 above illustration will fit all the haemolytic immune 

 bodies as well as all the bactericidal ones, or 

 are there a great many different complements? 



