232 STUDIES l\ IMMUNITY. 



Such an experiment planned to corroborate these theoretical 

 deductions from the Ehrlich and Morgenroth's hypothesis tails 

 completely to do so. Two exactly similar mixtures A and B are 

 prepared, containing each (>.'_' of a cubic centimeter of fresh hemo- 

 lytic serum from a guinea-pig that had been given four injections 



(from \ to 5 C.C.) of rabbit blood, and 1 c.C. of the heated (55 

 degrees) serum of a rabbit treated with hen blood. T<> mixture 

 A is added 0.6 of a cubic centimeter of defibrinated washed hen 

 blood; the corpuscles are soon destroyed. Nothing is added to 

 mixture B for the moment. 



A few hours later 2 drops of defibrinated rabbit blood are added 

 to each mixture. In mixture B destruction of the corpuscles is 

 complete in about 45 minutes. There is then enough alexin present 

 to destroy these corpuscles; we have, moreover, admitted that the 

 portion of the alexin that produces this effect was already com- 

 bined with the sensitizer for the corpuscles in question. The other 

 mixture, however, proves that this is not so. 



Mixture A is identical with B except it contains in addition hemo- 

 lyzed hen corpuscles. The rabbit corpuscles remain intact in this 

 mixture; even on the following day they may be discerned among 

 the nuclei of the hen corpuscles.* The hen corpuscles then have 

 used up all the alexin, and if we were to follow the hypothesis of 

 Ehrlich and Morgenroth, we should be forced to conclude that the 

 sensitizer acting on hen corpuscles had combined w r ith all the alexin, 

 preventing the other sensitizer (active against rabbit corpuscles) 

 from sharing it. Such a conclusion must also hold for mixture B 

 containing the same doses of the same sera. And yet in this mix- 

 ture B the sensitizer that has not combined with the alexin has 

 been able to destroy its appropriate corpuscles. There is no reason, 

 then, in explaining hemolysis, to assume that the sensitizer combines 

 with the alexin. On the contrary, it seems clear to us from this 

 experiment that the corpuscles modified by their union with the 

 sensitizer absorb the alexin directly and prevent it from acting on 

 other cells. When the corpuscle is not present the sensitizer in 

 no way fixes the alexin or prevents it from acting on the first properly 



* The destruction of the rabbit corpuscles takes place on addition of alexin 

 (normal guinea-pig serum) ; the corpuscles are then rapidly destroyed, showing 

 that they have absorbed their appropriate sensitizer. 



