BACTERIOLYSINS AND HMMOLYSINS IOI 



be loaded with complement, leaving a portion of 

 the inter-body uncomplemented. On adding the 

 corresponding bacteria a number of conditions may 

 result; the affinity of the inter-body for the bac- 

 terial receptor may, as a result of the loading with 

 complement, (i) remain unchanged, (2) it may 

 thereby be increased, or (3) be diminished. 



In the figure, B II shows the condition of in- 

 creased affinity. Of the six inter-bodies only those 

 combine with the bacterium which have become 

 laden with complement. In this case, therefore, 

 the excess of inter-bodies will have no influence on 

 the bactericidal effect. The condition is really the 

 same as A II, except that free inter-body is also 

 present. 



C II shows the condition of unchanged affinity. 

 In this case, if we add the bacterium to the mixture 

 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. 



