1904.] Combining Properties of Serum- Complements, etc. 19 



These results also confirm the result already obtained, namely, that 

 in the case under consideration the haptophore groups of the rabbit's 

 and guinea-pig's complements unite with the same R + IB molecules 

 (vide supra). 



Conclusions. 



The following are the chief results obtained from the experiments 

 described. It is, of course, to be understood that they are held to 

 apply only to the cases investigated, viz., the immune-body for ox's 

 corpuscles obtained from the rabbit, used along with rabbit's and 

 guinea-pig's complements and complementoids. Further observations 

 will be necessary to determine whether they 'obtain generally. 



(1) The existence of complementoids in heated sera can be shown 

 in ordinary test-tube experiments, by their preventing (a) the union 

 of complement with anti-complement, (b) the union of complement 

 with R + IB molecules after lysis. 



(2) The amount of complementoid derived from complement, as 

 tested by the combining relationships, varies ; in the case of the rabbit 

 it is approximately equal to the original amount of complement ; in 

 the case of the guinea-pig it is considerably less than that amount. 



(3) The combining affinity of complementoid, both for anti-comple- 

 ment and for R + IB molecules after lysis, is not much inferior to that 

 of complement. 



(4) On the other hand, complementoid has a feeble affinity for 

 R + IB molecules before lysis, i.e., for intact red corpuscles treated 

 with immune-body ; of the complementoid added only a small 

 quantity enters into combination ; hence complementoid does not 

 prevent lysis by complement. 



(5) When red corpuscles united with multiple doses of immune-body 

 are lysed by a single dose of complement, the surplus R + IB 

 molecules can be saturated with excess of complementoid, so that 

 almost no complement can subsequently be taken up. This result is 

 obtained also with rabbit's complementoid and guinea-pig's comple- 

 ment, and with guinea-pig's complementoid and rabbit's complement. 



C 2 



