IMMUNITY AND ANAPHYLAXIS 205 



similarly that mixture (i), since it did not produce haemo- 

 lysis, could not have supplied any complement. We have 

 therefore to examine mixtures (i) and (2) carefully to 

 determine the cause of their different actions. To do this,, 

 they may be rewritten thus : 



(1). Specific immune-booly -f- specific antibody-producer 

 -f- complement. 



(2) . Non - specific immune - body -f- specific antibody- 

 producer -f- complement. 



They differ only in their immune-bodies (normal serum 

 is believed to contain non-specific immune- bodies) . It is 

 therefore inferred that in (1), since no complement is left 

 free, it has become bound by the joint action of the specific 

 immune-body and the corresponding antibody-producer. 

 In (2), since the immune-body and the antibody-producer 

 do not correspond, no binding or fixation of the complement 

 occurs, and so haemolysis takes place on adding (a). It 

 should be noted here, that the quantity of complement 

 used is determined by previous experiment, as the presence 

 of an excess over the quantity which can be bound by the 

 amounts of immune-body and antibody-producer would 

 lead to haemolysis, even in (1). 



This reaction is capable of many applications in the 

 determination of specific immune-bodies in a serum and of 

 specific antiho ffo-prorhicers (antigens) in a serum. We 

 shall here describe briefly the so-called " Wassermann 

 test " for the diagnosis of syphilis, by determining the 

 presence in the patient's blood of an immune body, capable 

 when mixed with syphilitic antibody-producer (antigen) 

 of causing fixation of complement. 



Wassermann Test. Requisites : 



(1) Specific antibody-producer, referred to usually as 

 the antigen. 



(2) Red blood cells of a sheep, washed free of com- 

 plement. 



(3) Serum of a rabbit's blood, haemolytic to sheep's red 

 cells, heated before use, to destroy its complement. 



(4) Fresh guinea-pig's serum, to supply complement. 



(5) Serum from the patient, heated to 56 C, which 

 serum is to be tested for the presence of specific immune- 

 body or antibody. 



