652 COLLECTED STUDIES IN IMMUNITY. 



precipitate. It sheds no light on the possibility of antiamboceptors 

 being present in the antiserum at the same time. 



The solution of this problem is simplified if we succeed in excluding 

 the action of the precipitate and so permit the supposed antiambo- 

 ceptor to act by itself. This can be accomplished by anchoring 

 the amboceptor to the cell and removing the normal serum constit- 

 uents by centrifuging. From this point of view, one may even con- 

 sider the problem as already solved. The experiments of Bordet, 

 Ehrlich and Sachs, Muir and Browning, with hsemolytic amboceptors, 

 and those of Shibayama and Toyoda 1 with bacteriolytic amboceptors 

 all agree in showing that the antiamboceptor acts even when the 

 cell, loaded with amboceptor, has been separated from free serum 

 constituents. Nevertheless, in view of the small traces of albuminous 

 substance which suffice, when combined with suitable antibody, to 

 deflect complement, it might be objected that it is difficult to com- 

 pletely free the sedimented blood-cells from traces of adherent 

 albuminous substances. This difficulty would appear considerable, 

 especially if we incline to believe that the blood-cells have some 

 absorbing action on the albuminous substances. Furthermore, 

 the antiamboceptors sometimes do not act at once on the amboceptor 

 anchored to the cell. Bordet, for example, was unable to produce the 

 antiamboceptor action until he suspended the blood-cells in inactive 

 serum. This, of course, diminishes the value of the demonstration, 

 since it introduces a possible interference due to complementoids 

 (Muir and Browning) . Our own observations lead us to believe that 

 the ability of antiamboceptor to unite with the amboceptor bound to 

 the cell or with the free amboceptor is very variable. 



In view of these objections we have therefore attempted to demon- 

 strate the presence of antiamboceptors indirectly, by excluding the 

 action of antiamboceptors while allowing antibody and albuminous 

 substances to participate in the reaction. It would seem that the 

 simplest way to attain this would be to employ, as the source of 

 amboceptor, a different species of animal than was used for producing 

 the antiamboceptor. 



The antiserum used by us was obtained from a goat which had 

 been immunized with rabbit serum. 2 The amboceptor, of course, 



1 Shibayama and Toyoda, Centralbl. f. Bact., Orig. Vol. XL, 1906. 



2 The serum with which these animals were immunized was derived from 

 rabbits which had been treated with ox blood. It therefore contained specific 



