130 IMMUNE SERA 



of complement and excess of inter-body, all the 

 receptors of the bacterium will, to be sure, be occu- 

 pied by inter-bodies, but this will be entirely with- 

 out regard to the fact that these inter-bodies are or 

 are not loaded with complement. It may there- 

 fore happen that only a few of the bacterial receptors 

 will be occupied by complemented (i.e., active) 

 inter-bodies, while the rest of the bacterial receptors 

 are occupied by uncomplemented (hence inactive) 

 inter-bodies. As already stated, however, the 

 vitality of such a bacterium is not necessarily 

 destroyed. 



D II represents the last conceivable case. It i 

 assumed that the " completion " of the inter-body 

 has resulted in a diminution of the latter 's affinity 

 for the bacterial receptor. In this case primarily 

 only the uncomplemented inter-bodies will com- 

 bine with the bacterial receptors, while the free 

 fluid will contain complemented inter-bodies. 



In cases C II and D II, therefore, the excess of 

 inter-body exerts a deflecting action on the complement, 

 thus diminishing the end results. 



It is difficult to say to what extent " deflection of 

 complement " really occurs in the experiments 

 referred to above. Studies by Buxton, Gay, and 

 others show that deflection of complement will not 

 always explain the phenomenon, and that in these 

 instances other factors must be responsible for the 

 paradoxical results. 



