374 STUDIES IN IMMUNITY. 



Ehrlich and Sachs is evident. In their experiments guinea-pig cor- 

 puscles which remain intact, either in heated bovine serum or in 

 fresh horse serum, are destroyed by a mixture of the two. In our 

 experiment sensitized ox corpuscles act in the same manner. As 

 far as agglutination is concerned the analogy also is perfect. It is 

 probable, then, that both experiments are subject to a common 

 explanation. And, what is more, the explanation of Ehrlich and 

 Sachs would already seem untenable. 



It is not to be supposed that bovine serum contains an amboceptor 

 that unites with its own corpuscle and, on the other hand, with the 

 alexin of horse serum, or that this combination with the alexin is 

 necessary to produce a hypothetical union with the corpuscles. A 

 careful study of the facts, moreover, renders such a supposition 

 quite impossible. We may consider, then, in detail the data offered 

 by the experiment that we have reported. 



a. Is it necessary, in order to produce agglutination and hemoly- 

 sis of bovine corpuscles by means of horse serum and heated bovine 

 serum, that these corpuscles should be sensitized? We add to 0.5 

 of a cubic centimeter of a 20 per cent emulsion of unsensitized 

 corpuscles 0.3 of a cubic centimeter of each serum. Nothing occurs 

 and the corpuscles remain intact. Experiment shows, then, that the 

 corpuscles must be sensitized in order to be agglutinated and de- 

 stroyed, and that the necessary amboceptor acting upon ox corpuscles 

 is not present in ox serum. Experiment further shows that horse 

 serum has no distinct sensitizing effect for bovine blood corpuscles. 



b. The presence of alexin in the mixture is obviously necessary 

 for hemolysis; but is it equally indispensable for agglutination? 

 We add 0.3 of a cubic centimeter of heated bovine serum and 0.3 of 

 a cubic centimeter of horse serum heated to 56 degrees to 0.5 of a 

 cubic centimeter of a suspension of sensitized bovine corpuscles. 

 There is no hemolysis or agglutination. 



c. Does the horse serum simply furnish the alexin or does it 

 also furnish the principle that causes agglutination? If it only 

 furnishes the alexin it may evidently be replaced by any other 

 fresh serum, as, for example, fresh rabbit serum. This proves to 

 be the case, as the following experiment shows : We add to each of 

 two tubes 0.5 of a cubic centimeter of a suspension of sensitized 

 bovine corpuscles and to the first tube add 0.2 of a cubic centimeter 



