gS CLINICAL BACTERIOLOGY AND HvEMATOLOGY 



Experiments 7 and 8. — These are the same as Experiments 5 

 and 6, except that rabbit serum is used in place of human 

 serum. The results and explanations are the same, and show that 

 fresh rabbit serum contains complement, which is destroyed by 

 heat. 



Two further experiments show that amboceptor can attach 

 itself to corpuscles, whereas complement cannot do so. 



Experiment g. — Take the deposit from the tube in Experi- 

 ment I or 2, and add to it i unit of heated immune rabbit 

 serum, and incubate again. 



Result. — No haemolysis. 



Explanation. — The corpuscles have been exposed to the action 

 of complement in the first part of the experiment, but have not 

 absorbed it, or they would become dissolved when the heated 

 immune serum (amboceptor) is added. 



Experiment 10. — ^Take the deposit from Experiment 4, and 

 add to it I unit of fresh normal human or rabbit serum. 



Result. — -H ae molysis. 



Explanation. — In the first phase of the experiment the cor- 

 puscles had absorbed complement, or, as it is usually expressed, 

 had become sensitized. The second serum contained comple- 

 ment, and the conditions of haemolysis were reproduced. 



Experiments such as these lead us to regard the process of 

 haemolysis somewhat as follows : The amboceptor first combines 

 with the corpuscles, sensitizing them. Complement now com- 

 bines with the amboceptor, which acts as a sort of link, combining 

 the two substances together. The whole compound of corpuscle 

 — amboceptor — complement is called a " haemolytic system," and 

 undergoes solution at the body temperature. It will be obvious 

 that corpuscles which have been saturated with amboceptor, 

 or sensitized, provide a test for the presence of complement. 

 Add corpuscles so prepared to any specimen of serum, normal, 

 saline, etc., and if they are dissolved it shows that the fluid 

 contained complement, or vice versa. This is of fundamental im- 

 portance in the Wassermann reaction. 



For the sake of brevity we will omit any reference to the 

 theoretical interpretation of the Wassermann reaction — which is, 

 indeed, at present not properly understood — and will describe as 

 simply as possible the essentials of the test. They may be stated 

 in a few words : If a specimen of serum from a syphilitic person, 

 containing complement, be incubated after admixture with certain 



