ANTIAHBOCEPTORS. 271 



Inasmuch, however, as the immune serum contains 

 aniboceptors also, the antagonistic action of the 

 antiserum may depend, in part, on the presence of 

 antiamboceptors. Differentiation between the ac- 

 tion of anticomplement and antiamboceptor is dif- 

 ficult, but it may be accomplished in certain cases 

 by appropriate binding experiments. Serum 1, an 

 inactive hemolytic serum, i. e., a solution of ambo 

 ceptors and complenientoid, is treated with serum 

 2. Serum 2 has been obtained by immunization of 

 an animal with serum 1, and contains anticomple- 

 ment and possibly antiamboceptors. If serum 2 

 contains only anticomplement, it will have no ef- 

 fect on the amboceptors of serum 1, when the two 

 are mixed. The amboceptors are free to sensitize 

 corpuscles which may be added, and the latter when 

 sensitized undergo hemolysis in the presence of 

 complement. If, however, serum 2 contains anti- 

 amboceptors, either the cytophilous or the comple- 

 mentophilous haptophore of the amboceptor will 

 be bound. In either case, corpuscles which are 

 added subsequently would not appear as sensitized, 

 for if the cytophilous haptophore had been bound 

 by antiamboceptor union between cell receptor and 

 amboceptor could not occur; and if the comple- 

 inentophilous haptophore had been preoccupied 

 complement would have no effect even if the ambo- 

 ceptors had united with the cells by their unbound 

 cytophilous haptophores. Ehrlich and Morgenroth 

 demonstrated such antiamboceptors for certain 

 hemolytic serums, and it was their belief that they 

 combine with the cytophilous rather than with the 

 complementophilous haptophore of the ambo- 

 ceptor. However, Ehrlich has recently been able 

 to prove the occurrence of an antibody for the com- 



