634 COLLECTED STUDIES IN IMMUNITY. 



but also those of the guinea-pig. In this respect, therefore, our 

 results are somewhat opposed to the statements of Bordet and Gay. 

 For the sake of completeness it may be mentioned that ox serum 

 digested with guinea-pig blood which has previously been treated 

 with active horse serum loses nothing of its power to bring about 

 hsemolysis of prepared ox blood. 



To sum up: 1. Prepared ox blood treated with active horse 

 serum does not dissolve in inactive ox serum. 



2. The constituent of the ox serum which brings about hsemolysis 

 is not absorbed by prepared ox blood previously treated with horse 

 serum. 



This shows that the hsemolysis of prepared ox blood by the com- 

 bined action of inactive ox serum and active horse serum, as also 

 the hsemolysis of guinea-pig blood under the same conditions cannot 

 be explained on the basis of the colloid theory of Bordet and Gay. 

 We have seen that the simplest postulates of this theory cannot be 

 verified experimentally. In the haemolysis of guinea-pig blood it is 

 at once clear that it is not the horse serum, as Bordet and Gay 

 suppose, but the ox serum which furnishes the hsemolytic amboceptor. 

 This ox amboceptor, as Ehrlich and Sachs have shown, is peculiar 

 in that it requires first to be united with horse complement before 

 it can be anchored by the red blood-cells. 



In explaining the hsemolysis of prepared ox blood, it is impossible 

 to regard the ox serum as acting as an amboceptor, and Bordet and 

 Gay have very properly called attention to this fact. One might 

 perhaps think that the inactivated ox serum acts as a complementoid. 

 In that case, to be sure, the function of the complementoid would be 

 rather peculiar. It would be necessary to assume that the active 

 horse complement was bound by the amboceptor-laden blood-cells 

 at an unsuitable point so that the complement could not exert its 

 action, or, in other words, so that it was "not dominant." The 

 role of the ox complementoid would then consist in directing, as it 

 were, the horse complement in the right direction. One could, for 

 instance, imagine that the complementoid possessed a higher affinity 

 than the horse complement, and that it would thus block the ambo- 

 ceptor group at which the complement is not dominant. The horse 

 complement would thus be anchored by the complementophile 

 amboceptor group for which it really possesses the smaller affinity 

 but at which it is dominant. Still other interpretations are possible, 

 but it would always be necessary to assume that the ox complementoid 



