g6 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



Further investigation shows that this haemolytic power is 

 dependent on the presence of two substances, one of which occurs 

 in normal serum, whilst the other is formed as a result of the 

 injection. The first is called complement. It occurs in all serum, 

 though in varying amount ; it is easily destroyed by heat (55° C. 

 for half an hour, or 60° C. for ten minutes), and it disappears 

 spontaneously in a few days at the room temperature. It is 

 therefore a fragile substance, and is allied to the enzymes. The 

 second is called amhocepior. It rarely occurs in normal serum, 

 but is formed when alien corpuscles are injected : thus, a normal 

 rabbit serum contains no amboceptor for human corpuscles, but 

 acquires it after two or three injections. Amboceptor is not 

 readily destroyed, resisting heat that will destroy every trace of 

 complement, and it remains for months in serum kept at the 

 room temperature. Both these substances are essential for 

 haemolysis, and if one or other is present' alone, no solution will 

 occur. The proof of these statements is simple, and depends on 

 a series of experiments which, if the materials are at hand, may 

 be readily repeated. The requisites are, fresh human serum, 

 fresh serum from a normal rabbit, fresh serum from a rabbit 

 which has been injected with human corpuscles, the same three 

 sera heated to 60° C. for ten to fifteen minutes, and, lastly, an 

 emulsion of washed human corpuscles. This is prepared as 

 follows : Prepaire normal saline solution containing 0-9 per ceiit. 

 salt and about 2 or 3 per cent, sodium citrate. Into about 

 10 c.c of this solution drop a small amount (10 to 20 drops) of 

 blood from a finger-puncture, and centrifugalize until the 

 corpuscles are deposited and the supernatant fluid clear. Pour 

 off the supernatant fluid and replace it by ordinary normal saline, 

 mix well, centrifugalize down again, and repeat the process 

 once more. This will give you a deposit of corpuscles washed 

 from_ all trace of serum. Prepare a 10 per cent, emulsion of 

 these corpuscles in normal saline solution, using a pipette such as 

 is described in the section on the Widal reaction ; with this take 

 9 large units of saline solution and i of the deposit of corpuscles. 

 Mix them together. 



Experiment i. — Mix together i volume of fresh human serum, 

 I volume of normal saline solution, and i volume of the emulsion 

 of corpuscles. Use a pipette to measure out the volumes, and 

 mix them in a narrow test-tube, which is then to be incubated 

 in the ordinary incubator, or in the special form described below. 



