300 STUDIES IN IMMUNITY. 



quently diminish the hemolytic power of the fluid. Sensitized 

 corpuscles, therefore, used as a reagent for the destructive power, 

 would be less likely to be hemolzyed when added toa mixture of 

 alexin, antisensitizer and sensitizer, than when added to a mixture 

 of antisensitizer and alexin without sensitizer. This difference 

 would be due to the fact that in the first instance part of the alexin 

 would be consumed by the complex "sensitizer-antisensitizer," 

 which acts precisely as does "sensitizer-corpuscle," since, according 

 to Morgenroth, the terms antisensitizer and corpuscle receptor are 

 synonymous. 



Experiment confirms Morgenroth's expectations. By mixing, 

 in carefully chosen proportions, guinea-pig alexin, rabbit > ox 

 sensitizer (56 degrees) and goat > rabbit serum (56 degrees) it may 

 be shown that the alexin does not remain free. If sensitized cor- 

 puscles are subsequently added to such a mixture and at the same 

 time to another similar mixture without the sensitizer, hemolysis 

 appears in the second, but not in the first. 



Morgenroth, however, does not prove that the results are really 

 due to the substance which he holds responsible for them. There 

 is no proof that the disappearance of alexin is due to its combina- 

 tion with the rabbit > ox sensitizer united to the receptors of anti- 

 sensitizer. To prove that it is this sensitizer that uses up the 

 alexin, a control should have been made to show that the same 

 result is not obtained in a mixture of alexin, antisensitizer, and 

 an immune serum that has been already deprived of its specific 

 sensitizer.* 



It seems to us that Morgenroth's phenomenon should be explained 

 differently. In addition to the alexin there are two sera in the 

 experiment to be considered. The first (antisensitizer) has been 

 obtained by injecting goats with the second serum, namely, of 

 rabbits immunized with ox corpuscles. The first is certainly anti- 

 sensitizing for the second in the sense that it neutralizes its 

 specific sensitizer. But from another standpoint it may be re- 

 garded as sensitizing for the same serum, and this fact Morgen- 

 roth does not take into account. The antiserum (serum I) is 

 from animals injected with alien serum (serum II), and in this 

 respect should sensitize serum II if we consider this serum simply 

 * Or in a mixture of alexin, antisensitizer and normal rabbit serum. 



