SENSITIZING ANTIBODIES 207 



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 substance's to act together unit for unit. 



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

 noticed by Neisser and Wechsberg 52 that in mixing together bacteria, 

 inactivated bactericidal immune serum (im- 

 mune body), and complement in the test tube, 

 a great excess of immune body hindered rather 

 than helped bactericidal action. As the amount 

 of immune body in the mixture was carried 

 beyond the experimental optimum, bactericidal 

 action became less and less pronounced, and 

 was finally completed suspended. They explain 

 this by assuming that free immune body, un- 

 combined with complement, has a greater 

 affinity for the bacterial receptor than the im- 

 mune body combined with complement. The 

 complement is consequently diverted and pre- 

 vented from activating the amboceptor attached 



,11 . n I-, r* -i . -,. FIG. 37. NEISSER AND 



to the bacterial cell. Graphically, the condi- WECHSBBRG , S CoN . 



tions may be illustrated as follows : CEPTION OF COMPLE- 



The above theory of Neisser and Wechs- MENT DEVIATION. 

 berg is here stated simply because of the 



wide discussion it has aroused. In the light of our present 

 knowledge concerning the relations between antigen, ambo- 

 ceptor, and complement, their conception is obviously erroneous. 

 The phenomenon of Neisser and Wechsberg is probably a "zone" 

 phenomenon, namely, an occurrence which depends upon the fact 

 that the complete or incomplete union of colloidal substances de- 

 pends to a very great extent upon the relative concentrations of 

 each, and too high a concentration of the anti-serum in experiments, 

 such as those of Neisser and Wechsberg, may result in incomplete 

 union. Thus, it is possible in many colloidal precipitation phenomena 

 to show that too high a concentration of one or the other reacting 

 colloid will result in failure of precipitation, and in some cases, even 



52 Neisser und Wechsberg, Munch, med. Woch., xviii, 1901. 



