620 COLLECTED STUDIES IN IMMUNITY. 



has the following properties: It is stable, resisting long standing 

 and heating to 56. It is bound by the blood-cells only after these 

 have been loaded with amboceptor and complement. When so 

 bound it effects agglutination and haemolysis. Bordet and Gay 

 thus assume the existence of an entirely new substance in horse 

 serum, and ascribe to it very important properties. The inter- 

 pretation which these authors give of the phenomenon described 

 by Ehrlich and Sachs is merely an hypothesis entirely lacking in 

 proof. Granted that the role of the ox serum in the haemolysis 

 of sensitized ox blood by means of horse serum cannot be looked 

 upon as an amboceptor action, this by no means justifies the analogous 

 conclusion that in the haemolysis of guinea-pig blood by inactive 

 ox serum and horse serum the ox serum does not play the part 

 of an amboceptor. It should at least be shown that guinea-pig 

 blood digested with horse serum (whereby, according to the view 

 of Bordet and Gay, amboceptor and complement are bound) is 

 haemolyzed on the subsequent addition of inactive ox serum. Klein 

 and Browning, however, showed that this was not the case. The 

 latter, moreover, offered an explanation which harmonized per- 

 fectly with the amboceptor theory. Bordet and Gay themselves 

 failed when they attempted this crucial experiment. From the 

 fact that guinea-pig blood-cells which have been treated with horse 

 serum are strongly agglutinated by inactive ox serum, they con- 

 clude, however, that a binding of the " colloid " has occurred. We 

 should like to point out that haemolysis and agglutination cannot 

 be regarded as due to one and the same substance, and that con- 

 sequently there is no justification for the conclusion drawn by these 

 authors concerning the haemolytic constituent of ox serum. Bordet 

 and Gay, to be sure, seek to explain the failure attending this impor- 

 tant (for their conception) experiment by regarding the absence 

 of haemolysis as due to a marked antagonistic effect exerted by the 

 strong agglutination. They found that such agglutinated blood- 

 cells would not dissolve even when they were resuspended in a 

 fresh mixture of inactive ox serum and horse serum. We look in 

 vain, however, for an experiment which would have decided the 

 question absolutely. Thus, if the guinea-pig blood-cells digested 

 with horse serum really do absorb the haemolytic component of 

 ox serum, it should be possible to show that the ox serum has lost 

 the power to dissolve guinea-pig blood in conjunction with horse 

 serum. Bordet and Gay do mention that inactive ox serum which 



