646 COLLECTED STUDIES IN IMMUNITY. 



This, we believe, disposes of the objections raised by Bordet; 

 and Gay against the view that in the haemolysis of guinea-pig blood 

 the ox serum constituent acts as an amboceptor. Furthermore, a 

 thorough analysis has shown that the interpretation of Bordet and 

 Gay is directly opposed to a number of experimental observations. 

 In contrast to this we see that all the experimental findings fit in 

 perfectly with the view developed on the basis of the amboceptor 

 theory. The peculiar role of the ox serum is readily explained by 

 the high affinity of the complementophile groups which the serum 

 contains, or the high affinity of the amboceptor to the complement. 

 This applies not only to the haemolysis of guinea-pig blood, but also 

 to the haemolysis of prepared ox blood. It is unnecessary, there- 

 fore, to ascribe new and unique properties to the ox serum, as is done 

 by Bordet and Gay. In fact the apparent exceptions to the rule 

 are merely variations of the cytotoxic action whose occurrence can 

 be predicated from the view developed on the basis of the amboceptor 

 theory. 



Resume. 



1. Contrary to the view of Bordet and Gay, in the haemolysis of 

 guinea-pig blood by active horse serum and inactive ox serum, the 

 amboceptor is furnished by the ox serum and not by the horse serum. 



2. The guinea-pig blood absorbs the complement of horse serum 

 through the agency of a horse amboceptor which is not dominant 

 for the horse complement. 



3. Subsequent addition of ox serum to guinea-pig blood previously 

 treated with horse serum does not produce haemolysis, though 

 according to Bordet and Gay's view haemolysis should occur. Neither 

 is the haemolytic component of ox serum thereby bound. This proves 

 the incorrectness of Bordet and Gay's theory, according to which 

 a " colloid" of ox serum constitutes a third element in the cyto- 

 toxic action, and is absorbed by the blood cells laden with ambo- 

 ceptor and complement, thereby effecting solution of the cells. 



4. Against this a direct union of ox amboceptor and horse com- 

 plement is indicated by the fact that haemolysis is considerably 

 more rapid when the two sera are digested before the blood-cells 

 are added. 



5. It is possible by treating the horse serum with guinea-pig 

 blood at to abstract a large part of the amboceptor without 

 diminishing the complement content. Despite the loss of ambo- 



