120 CLINICAL BACTERIOLOGY AND HyEMATOLOGY 



saline solution, using an opsonin pipette; with this take 9 

 large units of saline solution and I of the deposit of cor- 

 puscles. 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. 



Result. No haemolysis. The corpuscles settle, leaving the 

 supernatant fluid clear and colourless. 



Explanation. The normal human serum contains no ambo- 

 ceptor. It contains complement, as we shall show subse- 

 quently. 



EXPERIMENT 2. This is the same as before, except that 

 fresh normal rabbit serum is substituted for human. The re- 

 sult and the explanation thereof are the same as before. 



EXPERIMENT 3. Take i volume of fresh serum from an 

 immunized rabbit, i volume of normal saline solution, and i 

 volume of emulsion of corpuscles. 



Result. The corpuscles will be dissolved, the fluid being 

 coloured red from the liberated haemoglobin, and there will 

 be practically no deposit. 



Explanation. The serum contains complement and ambo- 

 ceptor, the latter being the result of the injections, the former 

 a constituent of all fresh sera. 



EXPERIMENT 4. Take i volume of heated serum from an 

 immunized rabbit, i volume of normal saline, and i volume of 

 corpuscles, and incubate as before. 



Result. No haemolysis. The corpuscles will probably be 

 clumped, owing to the injection having caused the produc- 

 tion of an agglutinin, similar to that which causes the Widal's 

 reaction in typhoid fever, but they will not be dissolved. 



Explanation. The complement has been destroyed by heat, 

 and the serum contains amboceptor only. 



EXPERIMENT 5. Take i volume of fresh human serum, i 

 volume of heated immune serum, and again i volume of 

 corpuscles. 



Result. Haemolysis. 



Explanation. The fresh human serum, insufficient in itself 

 to cause haemolysis (see Experiment i), supplies the comple- 



