84 COLLECTED STUDIES IN IMMUNITY. 



It has previously been shown that such a rabbit serum is rich in 

 antigoat complement. We observed an analogous phenomenon, 

 whose nature may perhaps be identical with the above, in a rabbit 

 which had been treated with ox blood (blood-cells and serum) in 

 order to produce a specific hsemolysin. Ten days after the injection 

 of ox blood, the serum failed to show any solvent action whatever 

 on ox blood, in direct contrast to numerous previous cases. At 

 first we thought it possible that no immune body had been formed 

 in this case, for even the addition of an excess of complement 

 in the form of rabbit serum produced no solution. However, on 

 <?entrifuging the ox blood-cells after treatment with this abnormal 

 serum, and mixing them with salt solution and complement, we 

 found that even slight doses of immune serum caused marked so- 

 lution. The serum therefore contained plenty of immune body, 

 and this had been anchored by the blood-cells. The presence of 

 this immune body was obscured not only because the complement 

 was absent, but because this had been replaced by an anticom- 

 plement which neutralized the complement subsequently added. 

 Because of the anticomplement which it contained, this rabbit 

 serum manifested a marked inhibitory action on the strongly hsem- 

 olytic serum of another rabbit (one which had been treated with 

 ox blood). 



But what happened in this case after injection of ox blood rarely 

 occurs in such a conspicuous manner. More frequently it is found 

 that the serum in its active state possesses an exceedingly slight 

 solvent action, corresponding to a very small content of complement, 

 and that after heating it manifests a distinct anticomplementary 

 action. This evidently leads to the extreme case above described, as 

 is readily seen when the relations are expressed by means of a diagram. 

 (See figure.) 



In studying the question as to how these autoanticomplements 

 are formed, we must constantly bear in mind that normal serum 

 always contains complements in excess. Now it is difficult to see 

 what purpose would be served if at any time the normal comple- 

 ments, so important in cell economy, were paralyzed by autoanticom- 

 plements. We shall therefore have to assume that the normal 



in progress, this serum also lacks the power to activate certain bactericidal 

 immune bodies. The animals at the same time seem to suffer a decrease in 

 their resisting power against certain infections, a fact which may perhaps serve 

 to exhibit in the purest form the function of certain complements. 



