338 I'li.s i\ [MMUNITl 



and " B" the partial immune body for rabbit alexin. Rabbit alexin 

 cannot join "A" or hemolysis would be produced with the same 

 dose of immune body as when employing guinea-pig alexin. Now, 

 if we produce hemolysis with rabbit alexin in the presence of the 

 necessary amount of immune serum, the 1 "B" will be satisfied, 

 that is. one-eleventh only of the amboceptors will have their "com- 

 plementophilic " arms plugged, while 10 "A,'* or the remaining ten- 

 elevenths, will be attached to the stromata and be still ready to fix 

 many hemolytic doses of guinea-pig alexin. This is the logic of the 

 Ehrlich hypothesis. Experimentally we obtain the following results: 



Rabbit corpuscles are hemolyzed with rabbit alexin and guinea- 

 pig > rabbit heated immune scrum; the stromata arc then heated 

 to 55 degrees, which will destroy any rabbit alexin that may be free, 

 or prevent any further toxic action from it, but will leave the cor- 

 puscle-immune-body complex still unaffected as regards its further 

 absorption of the guinea-pig alexin by its supposedly unsatisfied 

 10 "A" amboceptors. In fact, we find that the alexin of the gui- 

 nea-pig subsequently added remains entirely free; not one slight 

 portion of it has been attached, as is shown by suitable controls. 

 In other words, the fixation of rabbit alexin will completely pre- 

 vent the subsequent fixation of guinea-pig alexin. The details of 

 the experiment follow. 



Minimal hemolytic dose of guinea-pig > rabbit immune serum, 55 

 degrees, for 0.025 of a cubic centimeter of washed rabbit corpuscles. 



with rabbit alexin 



with guinea-pig alexin 



Relation 10 : 1. 



THREE LARGE TUBES ARE PREPARED: 



Tube A. Washed rabbit corpuscles 



S. guinea-pig > rabbit, 55 degrees 



S. rabbit (alexin) 

 Tube B. Washed rabbit corpuscles 



S. guinea-pig > rabbit, 55 degrees 



S. rabbit, 55 degrees 

 Tube C. Washed rabbit corpuscles 



S. normal guinea-pig, 55 degrees 



S. rabbit, 55 degrees 



Contact at 37° C for 1 hour. 

 Tube A is perfectly hemolyzed. 

 Tube B, agglutination; no hemolysis. 

 Tube C, no change. 



