STUDIES ON ANTIAMBOCEPTORS. 657 



ment when combined with the corresponding antiserum. We know 

 from the researches of Fleischmann and Michaelis, 1 as well as from 

 those of Moreschi, 2 that an excess of the albuminous antigen inhibits 

 the deflection of complement. The same phenomenon is observed 

 in the precipitin reaction. From the control furnished by series 

 B, it is apparent that deflection of complement plays no part in the 

 antihsemolytic action noted in series A. It follows, therefore, that 

 the inhibition of haemolysis observed when large amounts of serum 

 are employed, is to be regarded as an antagonistic action exerted 

 by the normal serum on the antiamboceptor, and must be ascribed 

 to the normal amboceptors present. 



In spite of this we may assume that in both series the blood-cell 

 sediments contain an admixture of albuminous precipitate, for it 

 could easily be shown that the antiserum possessed precipitating 

 properties. The serum, to be sure, was rather weak, especially so 

 far as the intensity of precipitation was concerned. It is to be noted, 

 however, that even with the greatest excess of rabbit serum occurring 

 in our experiments, there was no failure of precipitate formation; 

 in fact, this increased in proportion to the amount of precipitable 

 substance employed. Granted then, that the blood-cell sediments 

 contained albumin precipitates, two alternatives may be offered 

 to explain the lack of deflecting power on complements. Thus, it 

 is possible that, despite the formation of a precipitate, there are no 

 antibodies which are able to bind complement, or, if present, none that 

 enter into the reaction. On the other hand, and this is important 

 so far as the amboceptor problem is concerned, it is to be noted that 

 with the technique employed by us, conditions have been introduced 

 which render occurrence of deflection difficult or impossible. In order 

 to produce deflection of complement, one proceeds by first mixing 

 the albuminous antigen, antiserum, and complement, and subse- 

 quently adding blood cells and amboceptor. In our experiments, 

 on the contrary, the resulting sediment already contains: 1, blood- 

 cells laden with amboceptor,. and 2, the precipitate. The complement 

 which is now added finds two alternative points of attachment, and 

 it depends entirely on the relative affinity possessed by these as to 

 where the complement will be bound. Had the complement been 

 allowed to react with the precipitate alone, it would undoubtedly 



1 Fleischmann and Michaelis, Mediz. Klin., No. 1, 1906. 



2 Moreschi, 1. c. 



