114 PROPERTIES OF ELEMOLYTIC SERA 



body from the guinea-pig. According to the lock and key 

 analogy, the complementophile groups of the immune- 

 bodies of the rabbit and the guinea-pig so far as they are 

 satisfied by the same complements would thus appear to be 

 the same. As, however, the anti-immune-body to the 

 rabbit's immune-body does not act on the guinea-pig's 

 immune-bodies, the complementophile groups would appear 

 to be different. It may also be remarked that a somewhat 

 similar contradiction apparently existed in the anti-com- 

 plement to the rabbit's complement not acting on guinea- 

 pig's complement, while both complements showed the same 

 combining affinities in lysis, i. e. in one instance they had 

 apparently different combining-groups, while in the other 

 the groups were similar. In this case, however, the apparent 

 contradiction has been explained by the facts established 

 regarding deviation of complement (p. 133). In the case 

 of anti-immune-bodies the difficulty might possibly be 

 explained by the different energy of combination in the 

 two instances, the anti-immune-body having a comparatively 

 weak affinity for rabbit's immune-body (as is shown by the 

 experiments) and no affinity for guinea-pig's immune-body, 

 whilst guinea-pig's and rabbit's complement, owing to their 

 strong affinity, will combine with either guinea-pig's or 

 rabbit's immune-body ; that is, qualitative differences come 

 out in the case of weak combination which are not seen 

 in the case of combination of a powerful nature. Against 

 such a view, however, is the fact that we have failed to 

 find any evidence that complement prevents the combination 

 of anti-immune-body with immune-body a result which 

 would point to the complement and anti-immune-body 

 uniting with different combining-groups. At present, 

 however, no definite conclusion can be drawn. All that 

 we can say is that anti-immune-body annuls the usual 

 result of the union of immune-body with receptor, that is, 

 prevents the combination of complement. 



