36 PROPERTIES OF H^MOLYTIC SERA 



two hours at 37 C., so as to allow fixation of complement ; 

 to each tube is added 1 c.c. of untreated corpuscles, and the 

 tubes are replaced in the incubator for another hour. (As 

 there is free complement present, lysis of the added corpuscles 

 will again be proportionate to the amount of immune-body 

 got by dissociation.) 



The result of such an experiment is that the amount 

 of lysis in the two series is practically the same ; in the tubes 

 containing originally from ten down to six doses complete 

 lysis of the added corpuscles has taken place ; whilst in 

 the other tubes partial lysis has occurred ; in the five-dose 

 tube almost complete lysis, in the four-dose tube distinct 

 lysis, in the three-dose tube very slight lysis, and hi the 

 two-dose tube no appreciable lysis. The procedure has also 

 been varied by estimating the amount of immune-body which 

 may be obtained (a) in one case after saturation with com- 

 plement, (b) in the other case after lysis of the corpuscles 

 with a single dose of complement. Here again the result 

 is practically similar. The amount of lysis in the two 

 series closely corresponds. In further experiments with 

 other sera, the results were not always identical, in some 

 cases there being rather more dissociation of immune-body 

 before the addition of complement than after the saturation. 

 The differences were, however, in no case great. 



These results have an important bearing on the question as 

 to the amboceptor constitution of immune-body. Mani- 

 festly, if immune-body forms a link between the molecules 

 of complement and the receptors of the red corpuscles, 

 then theoretically it should not be possible to dissociate 

 immune-body without complement. As we have seen, how- 

 ever, under the conditions of the experiments, complement 

 is not dissociated to any appreciable extent, nor is the 

 combination immune-body + complement separable ; on the 

 other hand, immune-body is always obtained after the 

 addition of complement in excess. There are, however, 



