PROPERTIES OF COMPLEMENTOIDS 47 



not the case, and we must conclude either that comple- 

 mentoid does not usually combine with R + IB, or that if it 

 does, it can be displaced by complement. So far as we 

 know, the existence of complementoids in such heated sera 

 has not been shown by test-tube experiments. We accord- 

 ingly bring forward the following methods which prove their 

 existence : 



IS COMPLEMBNTOID PRESENT IN SERUM HEATED AT 55 C. ? 



We have demonstrated the existence of complementoids 

 by two methods, viz. : (1) by showing that they combine 

 with R + IB molecules after lysis, and thus prevent a certain 

 amount of C from being taken up ; (2) by showing that they 

 combine with a serum -f- its anti-serum (with S + anti-S), and 

 thus diminish the amount of C which can be taken up by 

 such a combination. And, further, the variations in the 

 dosage of complement necessary to produce lysis when the 

 corpuscles are suspended in various heated sera instead of 

 salt solution seem only explicable on the supposition of the 

 existence of complementoids. We may state that the com- 

 plement to be tested has usually been heated for 1 J hours at 

 57 C., and in every case a test was made, to show that it 

 was devoid of haemolytic power ; we shall represent such 

 heated serum by Cd (complementoid). 



1. As was shown byEhrlich and Morgenroth, the addition 

 of Cd to red corpuscles treated with IB does not prevent the 

 combination of C and the occurrence of lysis. We may 

 represent this as follows, the small circle indicating a red 

 corpuscle : 



Result = lysis. 



The vertical dotted line indicates a period of incubation 

 for one hour, unless when otherwise stated. 



After lysis has occurred, however, Cd can combine with 



