452 STUDIES IN IMMUNITY. 



Beginning with their theory that the bovine sensitizer fails to 

 unite with guinea-pig corpuscles unless horse alexin is present, 

 Sachs and Bauer presuppose that a mixture of heated bovine serum 

 and horse alexin that has been prepared for some time, and in which 

 this combination may have taken place, should hemolyze guinea- 

 pig corpuscles more rapidly than a recently prepared mixture. 

 They declare that this can be experimentally proved. We have 

 repeated their attempts with different results. We have noted, 

 as we shall later consider, that a mixture of fresh horse serum 

 and heated bovine serum in suitable proportions is much less 

 active when it has been kept for some time before the guinea-pig 

 corpuscles are added. 



Having examined Sachs and Bauer's objection, to close the debate 

 we may relate certain experiments which prove in an irrefutable 

 manner the accuracy of Bordet and Gay's interpretation. The reason 

 that Ehrlich and Sachs' original experiment has given rise to so long 

 a discussion is due to the multiplicity of the substances present and 

 particularly to the fact that there are two amboceptors which can 

 supplant one another. The obscurity is due to the fact that fresh 

 horse serum contains a sensitizer as well as does the heated bovine 

 serum. Let us suppose, for a moment, that horse serum contains 

 alexin only. Under these conditions, on mixing the heated bovine 

 serum (which, according to Bordet and Gay, is sensitizing and, in 

 addition, contains the conglutinin) with horse serum an active 

 mixture is obtained. We both agree on this point. But if we were 

 to mix with such a horse serum containing alexin but no sensitizer. 

 bovine serum, 56 degrees r which had been previously subjected to 

 guinea-pig corpuscles, what should we obtain? Evidently, if Bordet 

 and Gay's theory is correct, the mixture should be inactive because, 

 although such a mixture contains conglutinin, it should have been 

 deprived of all amboceptor. If Ehrlich and Sachs are correct, on 

 the contrary, the mixture should be just as active, inasmuch as it 

 should still, according to these authors, contain the bovine sensitizer 

 which can unite and produce hemolysis only in presence of alexin. 



It would therefore be of service to have horse serum which con- 

 tains alexin but is unable to sensitize guinea-pig corpuscles. Such 



also of bovine alexin. We shall later refer to an experiment that proves this 

 fact. In addition it may be mentioned that these facts have recently been con- 

 sidered in detail by Bordet and Gay (see article, p. 398). 



