246 INFECTION AND IMMUNITY 



lysin. In the test done subsequently, a precipitin reaction may take 

 place and by thus removing complement may give a false result. The 

 absorption of complement by such precipitates takes place when the two 

 reacting factors, the precipitin and its antigen, are in dilution so high 

 a visible precipitate can not be observed. This fact, together with 

 others too complicated to be discussed in this place, have led us to the 

 belief that the so-called precipitins are true sensitizers, exerting toward 

 unformed proteins the same function that the so-called sensitizer or 

 amboceptor exerts toward cellular formed antigens. (See p. 241.) 



Quantitative Relationship Between Amboceptor and Complement. 

 Morgenroth and Sachs l have succeeded in showing that within certain 

 limits an inverse relationship exists between these two bodies. If for 

 a given quantity of red blood cells a certain quantity of amboceptor 

 and complement suffices to produce complete hemolysis, reduction of 

 either the complement or the amboceptor necessitates an increase of the 

 other factor. As amboceptor is increased, in other words, complement 

 may be reduced and vice versa. This result is of great importance in 

 arguing against the original conception of Ehrlich in supposing these 

 substances to act together unit for unit. 



Deviation of the Complement (Complement- Ablenkung) . It was 

 noticed by Neisser and Wechsberg 2 that in mixing together bacteria, 

 inactivated bactericidal immune serum (immune 

 Jff Iff Tjf body), and complement in the test tube, a great 



inn excess f i mmune body hindered rather than helped 

 U U U 1 Bactericidal action. As the amount of immune 

 body in the mixture was carried beyond the 



1^ ^ j^, ex p er j men t a i optimum, bactericidal action became 



// U ll ^ ess anc ^ ^ ess P ronounce d> an d was finally com- 

 IJ U +J pletely suspended. They explain this by assuming 

 that free immune body, uncombined with comple- 

 ment, has a greater affinity for the bacterial receptor 

 than the immune body combined with comple- 

 ment. The complement is consequently diverted 

 and prevented from activating the amboceptor at- 

 tached to the bacterial cell. Graphically, the 



conditions may be illustrated as follows : 



The above theory of Neisser and Wechsberg is here stated simply 



1 Morgenroth und Sachs, "Gesammel. Arb. fur Immunitatsforschung." Berlin, 

 Hirschwald, 1904. 



2 Neisser und Wechsberg, Miinch. med. Woch., xviii, 190L 



