4 IMMUNE SERA. 



haemolytic action of the former will be inhibited for 

 the reason that the complement necessary for the 

 haemolysis to take place has been bound by the 

 anti-complement. (See Fig. 3.) One must, how- 

 ever, observe the precaution to heat the anti-com- 

 plement serum of the rabbit to 55 C. before so mix- 

 ing it, in order to destroy the complement which it 

 contains and which would otherwise reactivate the 

 guinea-pig immune body. 



From the foregoing we see that either anti- 

 immune body alone or anti -complement alone is 

 able to inhibit the haemolytic action. Haemolysis 

 cannot take place when either of the two necessary 

 factors is bound and prevented from acting.* 



The anti-complements are specific bodies, i.e., an 

 anti-complement combines only with its specific 

 complement. Thus an anti-complement serum 

 derived from rabbits by treatment with guinea- 

 pig serum combines only with the complement of 

 normal guinea-pig serum, not, however, with the 

 complements of other animals. Exceptions to this 

 are those cases in which the complement of the 

 other species possess receptors identical with those 

 of the first. 



* By treating animals with normal sera of certain other 

 species it is possible to produce not only anti-complements 

 but also specific anti-bodies against certain other con- 

 stituents of normal serum. These are, for example, anti- 

 agglutinins, which inhibit the action of the hasmagglu- 

 tinins of normal serum, and anti-precipitins, which we shall 

 discuss later. 



