THE MECHANISM OF THE ACTION OF AMBOCEPTORS. 211 



TABLE I. 



1 The amount of blood used in our experiments is always 1 cc. of a 5% suspension in . 85% 

 salt solution. 



be effected. Hence the amboceptor must have been bound by the blood- 

 cells. 



How then, through this previous binding, had the amboceptor 

 lost its power of being activated? After excluding all other possible 

 explanations we were forced to conclude that the phenomenon observed 

 is due to a blocking of the complementophile groups of the dog serum's 

 amboceptor by the complementoids still present in the inactive serum. 

 The correctness of this view has to our minds been confirmed: 



1. By the isolated binding of the amboceptor at C. 



2. By the subsequent blocking of the amboceptor bound at C., 

 by means of free complementoids. 



3. By the behavior of dog serum inactivated by shaking with 

 yeast. 



4. By the combining experiment with inactive dog serum (inac- 

 tivated by heat) when the salt content of the fluids was increased. 



We shall take these up in order. 



1. If we repeated the combining experiment above mentioned, 

 modifying it, however, so that the amboceptor was anchored by the 

 blood-cells, not at 37 C., but at C., we could show that the guinea- 

 pig blood-cells, treated in this way at C., were all activated by guinea- 

 pig serum. (See Table II.) 



Now we know that at 0, as a rule, only the amboceptor is bound 

 by the blood-cells, and that the complement for the most part is 

 uninfluenced. It is, therefore, perhaps quite natural in those cases 

 in which the complementoids, like the complements, are bound by 



