228 COLLECTED STUDIES IN IMMUNITY. 



A case described by Ehrlich and Sachs makes this clear, and 

 we shall therefore briefly reproduce it here: l 



Two amboceptors are concerned, namely, the normal ambocep- 

 tor of goat serum for rabbit blood, and an amboceptor obtained 

 by immunizing goats, which is anchored by ox blood-cells. We 

 shall for the sake of simplicity designate these amboceptors as A 

 and B. 



Naturally both these amboceptors are activated by goat serum, 

 in which we shall have to assume at least two complements x and b. 

 For immune body A, x is the dominant complement; for B it is 6. 

 If in one of the two combinations, for example, in that of rabbit 

 blood-cells loaded with immune body A, the serum is allowed to act 

 long enough, both complements will be bound; that is, dominant 

 and non-dominant. The result, however, is entirely different if the 

 action be made as short as possible. In this case the fluid obtained 

 on centrifuging the blood-cells still contains the dominant comple- 

 ment x, while it has for the most part lost the non-dominant com- 

 plement 6. We observe the surprising result that the immune body 

 A with which the blood-cells are loaded combines with the non- 

 dominant complement before it combines with its own dominant 

 complement. 



In this case, therefore, amboceptor A's complementophile groups 

 which combine with the complement must possess a higher affinity 

 for the non-dominant complement b than for the dominant comple- 

 ment x. Here then the binding of the non-dominant complement is 

 independent of the binding of the dominant complement. Such a 

 behavior, of course, is not a general rule; it was not long before 

 a case was found in which the contrary was true, i.e., in which the 

 non-dominant complement does not combine until after the dominant 

 complement has been bound. 



. The demonstration of this relation succeeded only because in a 

 certain human ascitic fluid an anticomplement was present whfch 

 acted only against part of the complements of a serum. The peculiar 

 behavior of this anticomplement has been described in a recent com- 

 munication by Marshall and Morgenroth, 2 and is also readily seen 

 in the following experiment. The complements here concerned are 



1 For the sake of clearness the case has here been somewhat simplified. The 

 details of this experiment are found in Ehrlich and Sachs, page 195. 



2 See page 222. 



