RELATIONS OF SENSITIZERS TO ALEXIN. 373 



mixture of heated bovine serum and horse alexin. It is evident in 

 such an experiment that not only is a sensitizer in the bovine serum 

 unnecessary, but that no such an iso- or auto-sensitizer can exist.* 



We take, then, bovine corpuscles that have been well sensitized 

 by immune serum from the rabbit. On the addition of alexic 

 horse serum neither hemolysis nor agglutination occurs, f But 

 the addition of the horse serum plus heated bovine serum produces 

 an extreme agglutination followed by slow but distinct hemolysis. 



The details of this experiment are as follows: 



Well-washed bovine corpuscles are treated with three volumes 

 of rabbit antibovine serum. Two or three hours later the excess 

 of serum is removed by washing in salt solution and the superna- 

 tant fluid rejected. Salt solution is then added to the corpuscle 

 sediment so as to make a 20 per cent suspension. Three tubes are 

 made as follows: 



Tube 1. Fresh horse serum, 0.3 c.c. 



Tube 2. Bovine serum (56 degrees), 0.3 c.c. 



Tube 3. Fresh horse serum, 0.3 c.c. + bovine serum, 56 degrees, 

 0.3 c.c. 



To each tube is then added 0.3 of a cubic centimeter of sensi- 

 tized bovine corpuscles. As a result, no agglutination or hemoly- 

 sis in tubes 1 and 2; rapid agglutination followed by hemolysis in 

 tube 3. 



Such a result is unexpected and paradoxical in view of current 

 ideas on sera. It is quite conceivable that sensitized ox corpuscles 

 should remain intact in horse alexin, for we know that the alexins 

 of certain species are too weak, or are unsuitable for hemolysis. 

 But the fact that the addition of the very serum that should be most 

 inactive, namely, the proper serum of the corpuscles employed, 

 should destroy the corpuscles is at least peculiar. This serum, 

 moreover, has lost its alexin through heating. It is also a surprising 

 fact that this form of agglutination requires the cooperation of two 

 sera, neither of which alone affects the corpuscles in question. 



The analogy between this experiment and the one described by 



* In most of these experiments bovine serum and corpuscles from the same 

 individual were employed. 



t It is also to be noted that the rabbit antibovine serum, although highly 

 sensitizing, has little or no agglutinating property. 



