RELATIONS OF SENSITIZERS TO ALEXIN. 375 



of rabbit alexin; to the second 0.2 of a cubic centimeter of rabbit 

 alexin plus 0.3 of a cubic centimeter of heated bovine serum. The 

 corpuscles in both tubes hemolyze, as the rabbit alexin is strongly 

 hemolytic for the sensitized corpuscles. But the hemolysis is 

 preceded in the second tube by an extraordinary agglutination 

 which does not occur in the first. A control tube shows that neither 

 agglutination nor hemolysis would have taken place if an emulsion 

 of normal bovine corpuscles, instead of sensitized bovine corpuscles, 

 had been employed. It is, then, the bovine serum and not the horse 

 serum that furnishes the agglutinating principle, and, as we have 

 already determined, agglutination takes place only when the cor- 

 puscles are treated both with a sensitizer and with an alexin. The 

 origin of this alexin, however, is indifferent and may be either from 

 horse serum, rabbit serum or even, as we shall see, from bovine 

 serum itself. 



We add to each of two tubes 0.2 of a cubic centimeter of fresh 

 non-heated bovine serum. To the first tube we then add 0.5 of a 

 cubic centimeter of normal bovine corpuscles and to the second tube 

 an equal amount of bovine corpuscles that have already been treated 

 with rabbit antibovine serum. There is a rapid agglutination of 

 the corpuscles in the second tube, but none in the first. 



To sum up, we find that, in presence of any alexin, bovine serum 

 will agglutinate corpuscles of the same species (and even of the 

 same animal) provided they be sensitized. When the alexin is 

 only weakly hemolytic, as is the case with horse alexin, its task is 

 greatly facilitated by the addition of bovine serum. In other words, 

 this serum not only agglutinates sensitized corpuscles that have 

 been subjected to alexin, but changes these corpuscles in such a 

 way that alexin that might otherwise be impotent becomes strong 

 enough to produce hemolysis. This explains why sensitized bovine 

 corpuscles which show no effect when subjected to horse alexin are 

 agglutinated and hemolyzed when heated bovine serum is added.* 



Bovine serum causes bovine corpuscles to be more easily destroyed 



* It is to be noted that we do not say that it is on account of its agglutination 

 that ox serum renders corpuscles more accessible to the action of a weak alexin. 

 What we do say is, that bovine serum renders corpuscles more accessible to alexic 

 activity and in addition produces a very marked agglutination. It is not owing to 

 the fact that the corpuscles are clumped that they become more susceptible to the 

 alexin, as we shall later see. 



