JOINT ACTION OF SEVERAL AMBOCEPTORS. 



637 



/Series C. The supernatant fluids separated in B are digested with the 

 sediments each of 1 cc. 5% prepared ox blood (prepared in the usual way with 

 0.05 cc. amboceptor) plus 0.1 cc. inactive ox serum. 



The result is shown in the following table: 



TABLE XI. 



Total volume always 2 cc. 



The table shows that so far as the binding of horse complement 

 is concerned, ox serum which has been prepared with one-tenth the 

 amount of amboceptor (0.005 cc.) behaves exactly the same as 

 that which has been highly prepared (0.05 cc. amboceptor). In 

 spite of this, we see that such feebly prepared ox blood is resistant to 

 the combined action of horse serum and inactive ox serum (Series A) . 

 Furthermore, from Series B it is apparent that the successive addi- 

 tion of horse serum and inactive ox serum does not lead to haemo- 

 lysis. The conditions discussed above have thus been fulfilled, 

 and the result shows that the phenomenon of the binding of horse 

 complement must be considered apart from that of its haemolytic 

 action. 



The following is probably the simplest conception we can make 

 of the mechanism of the entire phenomenon. In view of the multi- 

 plicity of amboceptors in a given immune serum (see especially the 

 studies of Ehrlich and Morgenroth) there is no reason why we should 

 not be dealing with two different fractions of amboceptor in the 

 immune serum used to prepare the ox blood. One amboceptor is 

 present in high concentration and binds the horse complement, 

 although the complement is not dominant for this amboceptor. 



