112 COLLECTED STUDIES IX IMMUNITY. 



tophile groups come into play. With the means at present at our 

 disposal it is impossible, except in a few favorable cases, to deter- 

 mine whether this plurality of complementophile groups corresponds 

 exactly to a like plurality of cytophile groups. A case in point 

 is that of the partial immune body which is reactivated by goat 

 serum, for which we could show that it was not diverted by our 

 anti-immune body. 1 



The difficulty of a full analysis of these cases is due especially 

 to the many possibilities that must be considered. It is possible 

 that immune bodies with different cytophile groups possess the same 

 complementophile group, or that those with the same cytophile 

 group possess different complementophile groups; and finally it is 

 possible that, besides a particular cytophile group, an immune body 

 may possess two, three, or more complementophile groups (triceptor, 

 quadriccptor) . 



In any case it may be considered a fact that in the immune-body 

 mixture different kinds of complementophile groups come into play. 

 Were we to assume that the serum of an animal species contains 

 only a single complement, we should have to regard such a plurality 

 of complementophile groups as evidently a useless arrangement. 

 It seems incredible that a given organism should form haptophore 

 groups in its cells (for the immune bodies are merely thrust-off cell 

 derivatives) if these groups were never during life to come into action, 

 but were only to be of service in case the organism were injected 

 with foreign cells. It is much simpler and more natural to view 

 these circumstances from our standpoint, namely, that the comple- 

 ments of an animal are, from the first, of manifold variety. 



This assumption best harmonizes the results of the various experi-^ 

 ments which we have made from the beginning of our studies in 

 haemolysis. By filtering goat and horse sera through Pukall filters 

 we were able to demonstrate two complements. One of these, fitting 



1 In our fourth communication we have discussed analogous cases in 

 detail, subjecting them to thorough experimental investigations. At that 

 time, however, our studies were directed only to the complementophile groups. 

 In that case the serum of guinea-pigs immunized with rabbit blood contained 

 two immune bodies, of which one found its complement in guinea-pig serum 

 but not in rabbit serum. These immune bodies were present in the propor- 

 tion of 1 : 10. In another case mentioned at that time we observed consider- 

 able chronological variations in the proportion of two immune bodies with 

 different complementophile groups. 



