PROPERTIES OF ANTISENSITIZERS. 291 



hypothesis — namely, that one and the same anti-agglutinin (or 

 antisensitizer) will neutralize indifferently the various agglutinins 

 formed by a given animal species — should we not be justified in 

 asserting that the two agglutinins in question, both affecting hen 

 blood corpuscles, are not identical, but show distinct differences as 

 marked, let us assume, as those between immune agglutinins from 

 the same animal species affecting different cells? Why, in fact, 

 should we accept without experimental proof the thesis that 

 Wassermann and Ford consider axiomatic, that there is a specific 

 antibody exclusively fitted for each active substance and that, con- 

 versely, when two substances are neutralized by a given antibody 

 that they are identical? Why, in short, must we conclude from 

 Ford's experiment that immunization simply increases the amount 

 of the active substance without changing it qualitatively? It is 

 evidently indispensable to consider this question before we can 

 admit Wassermann and Ford's conclusion, the importance of which 

 in increasing our comprehension of the genesis of active substances 

 in immune sera is evident. We shall see from the following experi- 

 ments, as a matter of fact, that a given antisensitizer can neu- 

 tralize distinctly different sensitizers affecting different cells. 



When we mix our antiserum with sensitized and washed ox 

 corpuscles the antisensitizer is, as we know, used up in curing the 

 corpuscles, so that the supernatant fluid after centrifugalization 

 no longer protects sensitized blood corpuscles. But will this fluid 

 still protect other corpuscles sensitized with a different rabbit sen- 

 sitizer, for instance, hen corpuscles treated with rabbit > hen 

 serum? The experiment, the details of which follow, proves that 

 it will not. The same antisensitizer neutralizes, then, two different 

 sensitizers (rabbit > ox and rabbit > hen). In a control it is 

 shown that ox corpuscles treated with rabbit > hen serum (which 

 they do not absorb) will not remove from the antiserum the power 

 of protecting sensitized hen or ox corpuscles. In the same way 

 it is shown that rabbit > ox serum does not sensitize hen cor- 

 puscles. 



Washed ox blood, the volume of which equals the primitive 

 blood, is placed in equal amounts in two large tubes (1.5 c.c.) and 

 two volumes (3 c.c.) of rabbit > ox serum, 56 degrees added to one, 

 and the same amount of rabbit > hen serum, 56 degrees, to the 



