630 



COLLECTED STUDIES IN IMMUNITY. 



conjunction with inactive ox serum still produces complete haemolysis. 

 Herein we see the first difference between this haemolysis and the 

 haemolysis of guinea-pig blood, for in the latter the horse serum was 

 always inert or only feebly haemolytic. Moreover, he have en- 

 countered further marked differences which speak strongly against 

 the identity of the mechanism in the two cases which Bordet and 

 Gay cite as analogous. Thus it was found that an excess of ox 

 serum inhibits the haemolysis of the prepared ox-blood cells by horse 

 serum plus ox serum, whereas the degree of haemolysis of the guinea- 

 pig blood cells is proportionate to the amount of ox serum. This is 

 shown in the following experiment: 



Two series of tubes were prepared: 



Series A. One cc. prepared 5% ox blood plus decreasing amounts of inactive 

 ox serum plus 0.15 cc. horse serum (minimum amount). 



Series B. One cc. 5% guinea-pig blood plus decreasing amounts of inactive 

 ox serum plus 0.25 cc. horse serum (minimum amount). 



The degree of haemolysis is shown in Table VII. 



TABLE VII. 



The behavior of the ox serum in the two series is totally 

 different, so that it is impossible to ascribe the action of the serum to 

 one and the same cause. According to Bordet and Gay, however, 

 the ox serum in both cases acts neither as amboceptor nor as com- 

 plement, but participates in the reaction as a colloid as already 

 discussed. From this standpoint it is impossible to understand the 

 difference in the behavior or the ox serum in the two series. Looked 

 at from our point of view, however, the difference is readily explained, 

 for then we regard the ox serum as acting as an amboceptor in the 



