1904.] Combining Properties of Serum-Complements, etc. 9 



of the red corpuscle or bacterium, the complement is the toxic agent 

 which leads to its partial or complete destruction, the auxiliary action of 

 the immune-body being, however, necessary. From his study of changes 

 which occur in toxins and their neutralisation by anti-toxin, he came 

 to the conclusion that the toxophore group might undergo degene- 

 ration while the haptophore group survived, though its combining 

 energy might be weakened. To such an altered toxin he gave the 

 name toxoid. The results of haemolytic studies led him to the con- 

 clusion that a similar change might occur in complements, the result 

 being complementoids. The chief evidence for the existence of com- 

 plementoids is the following : 



In most cases when normal sera are heated to 55 C. for an hour, the 

 characteristic action (haemolysis, bacteriolysis) of complement is lost, 

 but such a serum when injected into an animal of different species has 

 the faculty of leading to the formation of anti-complement. Hence, 

 apparently the zymotoxic group of the complement has been destroyed, 

 while the haptophore remains. Again, Ehrlich and Sachs* showed in 

 the case of the haemolytic action which the dog's serum normally 

 possesses towards the guinea-pig's corpuscles, that the combining group 

 of the R + IB molecules might be filled up by complementoid, and thus 

 the action of complement, i.e., haemolysis, might be prevented. In 

 most instances, however, this is not the case, and we must conclude 

 either that complementoid 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, though the production of anti- 

 complements by them is strong presumptive evidence in favour of their 

 -existence. We accordingly bring forward the following methods which 

 prove their existence : 



Is COMPLEMENTOID PRESENT IN SERUM HEATED AT 55 C. 1 



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 anti-C, and 

 thus diminish the amount of C which can be neutralised by a given 

 amount of anti-C. We may state that the complement to be tested has 

 usually been heated for 1 J hours at 57 C., arid in every case a test 

 was made, to show that it was devoid of haemolytic power. 



(1) As was shown by Ehrlich 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 : 



* Ehrlich. and Sachs, ' Berlin Klin. Wool).,' 1902, No. 21. 



