MECHANISM OF THE ACTIOX* OF ANTIAMBOCEPTORS. 571 



ceptor remains a loose one, while in the other case it becomes firm. 

 The following diagram may help to make this clear. See Fig. 1. 



We shall designate the two complementophile groups of the ambo- 

 ceptor as a and /?; the effective antiamboceptor corresponding to 

 group a is a, the antibody fitting group /? is 6. In small quan- 

 tities of antiserum, b can practically be disregarded owing to its 

 slight concentration ; a therefore by occupying a prevents the comple- 

 ment uniting with the amboceptor. In larger quantities of anti- 

 serum, however, b comes into play, so that the occupation of group /? 



Loose Union 



FIG 1. a and /?: Complementophile groups of the amboceptor. a and 6 are 

 Partial Substances of the Antiserum. a is the effective Antiamboceptor; 

 b is the antibody which inhibits the action of the antiamboceptor. c is the 

 Complement. 



changes the reactive capacity of group a in such a way that either a 

 is not bound at all w r hile the corresponding complement is, or so 

 that, wh le a may still be bound, the union is such a loose one that 

 the complement still has access. We shall see that the latter pos- 

 sibility is the more probable. First, however, it will be necessary 

 for us to understand clearly the manner in which normal rabbit 

 serum overcomes the influence of the antiserum constituent 6. In 

 view of what has been said this will not be difficult, for it is but a 



