362 STUDIES IN IMMUNITY. 



These experiments show a Neisser-Wechsberg phenomenon in 

 hemolysis. The result may be described by saying that blood 

 (i.e., serum plus corpuscles) is not hemolyzed by a small dose of alexin 

 unless the .amount of sensitizer is suitably small. Too much sen- 

 sitizer protects the corpuscles by deviating the alexin. This 

 deviation (Komplemenablenkung) , however, is not to be explained 

 as Neisser and Wechsberg have done. It is not due to alexin 

 absorption by means of a certain amount of uncombined sensi- 

 tizer remaining free in the fluid. The fixation of alexin is brought 

 about by a sensitized precipitum that competes successfully with 

 the corpuscles in absorbing this active substance. 



It is particularly to be noted that no Neisser and Wechsberg 

 phenomenon occurs if the corpuscles employed have been washed 

 free of the serum present in the primitive blood. 



Will this interpretation of alexin fixation in hemolysis account 

 for the Neisser-Wechsberg phenomenon in bacteriolysis? We 

 expect. to take up this question at a later time. It may be noted 

 here that a culture or emulsion of bacteria contains elements that 

 correspond rather closely to those present in blood. The bacteria 

 correspond, of course, to the corpuscles, the bacterial precipitino- 

 gens, that, as Kraus has shown, rorm precipitates with the specific 

 antiserum, moreover correspond to the albuminous substances in 

 serum. 



