134 COLLECTED STUDIES IN IMMUNITY. 



C. It is due to anticomplements which arise during the immu- 

 nizing process (Gruber). 



I shall critically examine each of these objections beginning 

 with the first. 



A. Is the Deflection of Complements in any way Connected with 



Agglutination ? 



This very natural objection, namely that each immune serum 

 agglutinates the corresponding bacteria and that it is this mechanical 

 effect of clumping which causes the bactericidal power of the immune 

 serum to fail, Neisser and Wechsberg sought to overcome by the 

 following method of procedure. They first agglutinated the bacteria 

 which were to be used in the cultures, and then studied the effect 

 that a normal and an immune serum exerted On these, with the 

 result that a deflection of complement was obtained only with the 

 immune serum. The following experiment also shows that the 

 agglutinating action of an immune serum is in no way the cause 

 of the deflection of complement; for in it I succeed in showing 

 that an immune serum which agglutinates strongly is nevertheless 

 unable to exert any deflecting action on the complements. 



In this experiment two immune sera acting against vibrio 

 Metchnikoff are employed, namely, that of a goose (A) and that 

 of a goat (B). Both sera strongly agglutinate vibrio Metchnikoff, 

 i.e., even in a dilution of 1 : 1000. The method of procedure is such 

 that decreasing amounts of the inactive sera were reactivated with 

 rabbit serum (column 1) and with pigeon serum (column 2). Now 

 while the immune serum of the goat (B) shows a typical picture of 

 deflection of complement, the immune serum of the goose (A), whose 

 bactericidal power is just as strong as that of the goat serum, is 

 unable despite this large content of amboceptor to deflect the com- 

 plement. This proves that the agglutinating action and that of 

 complement deflection are two properties of one and the same immune 

 serum, which may exist side by side, but that agglutination in no 

 way causes deflection of complement. 



According to our view the reason why the surplus amboceptor 

 of the goose immune serum fails in our experiment to bring about a 

 deflection of complement is because there is not sufficient affinity 

 between the complements of pigeon and rabbit serum on the one 

 hand and the free amboceptor of the immune serum on the other. 



