RELATIONS OF SENSITIZERS TO ALEXIN. 377 



serum that attaches itself to sensitized and alexinized corpuscles 

 as "bovine colloid." 



Before we endeavor to explain the accuracy of the interpretation 

 that we have just offered, we may apply it to the hemolysis of guinea- 

 pig corpuscles, since these are the corpuscles that are used in 

 Ehrlich and Sachs' experiment. To render the transition between 

 the experiments we have just recounted and the experiment of 

 Ehrlich and Sachs more simple, we may deal first with guinea-pig 

 corpuscles that have been sensitized in the same manner as were 

 our bovine corpuscles, that is to say, with a specific antiguinea- 

 pig serum (a serum, heated to 56 degrees, from a rabbit that had 

 been immunized against guinea-pig blood). 



These sensitized guinea-pig corpuscles are hemolyzed by fresh 

 guinea-pig serum, although the hemolysis is rather slow, particularly 

 when the amount of alexin employed is small, owing to the fact 

 that the alexin comes from the same animal species. Under such 

 conditions, by analogy with the experiments already considered, the 

 addition of heated bovine serum should have a distinct accelerating 

 action on the hemolysis. The addition of this serum, moreover, to 

 these sensitized corpuscles that have been mixed with alexin should 

 bring about very marked agglutination. 



These expectations are experimentally confirmable. Sensitized 

 guinea-pig corpuscles are, to be sure, already distinctly agglutinated 

 by rabbit antiguinea-pig serum, but as soon as the alexin and heated 

 bovine serum are added the agglutination becomes much more 

 marked. The corpuscles are immediately collected into large 

 glistening clumps which are soon hemolyzed. The bovine serum 

 produces no such agglutination with the sensitized corpuscles when 

 no alexin is present; the bovine colloid, we repeat, affects corpus- 

 cles only when they have been both sensitized and alexinized. 

 The analogy, then, between this experiment and the one with 

 sensitized ox corpuscles is complete. The details of the experi- 

 ment follow:* 



* It is to be noted that the particular rabbit antiguinea-pig serum that we 

 have used for this experiment was obtained by injecting rabbits with carefully 

 washed guinea-pig red blood cells. This antiguinea-pig serum was neither 

 precipitating nor anti-alexic for guinea-pig serum; if it had been, the experiment 

 might have been vitiated by a neutralization of the guinea-pig alexin in the tubes 

 3 and 4 following. 



