516 THE TECHNIC OF COMPLEMENT-FIXATION REACTIONS 



white rats are infected with surra by injecting 0.2 c.c. of blood from a 

 rabbit with this disease. If a large number of tests are to be made, the 

 rats should be so infected that one or two are available each day for the 

 preparation of the antigen. 



The spleen from a rat with a small amount of salt solution added is 

 ground in a mortar until a pulpy mass results. More of the salt solution 

 is added from time to time, and the suspension thus obtained is filtered 

 twice through a double layer of gauze and diluted with salt solution to 

 40 c.c. 



The anticomplementary and antigenic doses are then determined, 

 and the extract used in double the antigenic unit, providing that this 

 amount is not more than half the anticomplementary dose. If a posi- 

 tive serum from an infected horse is not available, the anticomplementary 

 dose may be determined and half this amount used in conducting the 

 main test. 



Anticomplementary Titration. Into a series of six test-tubes place 

 increasing amounts of antigen 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 c.c.; add 1 

 c.c. of complement (1 : 20) and sufficient salt solution to bring the total 

 volume in each tube up to 2 c.c. Incubate for one hour in a water-bath 

 at 38 C. or, preferably, in a refrigerator ot 8 C. for six hours or 

 over night. Add 2 units of antisheep amboceptor (determined by pre- 

 liminary titration) and 1 c.c. of 2.5 per cent, sheep's corpuscles. Incu- 

 bate for one hour in a water-bath, after which the reading is made. 



The Test. The serum is inactivated and used in dose of 0.15 c.c., 

 since it has been found that fixation in this quantity is obtained only 

 with serums of horses affected with dourine. In some instances the 

 serum of horses has reacted in doses as small as 0.02 c.c., and the reac- 

 .tion may be conducted with increasing doses of serum 0.05, 0.1, and 

 0.15 c.c. in exactly the same manner as when the glanders reaction is 

 performed. The same Controls are included. 



COMPLEMENT-FIXATION TEST IN TYPHOID FEVER 

 This was one of the original diseases in which Bordet and Gengou 

 first demonstrated the occurrence of complement fixation. Widal and 

 Lesourd attempted to make practical application of this method in the 

 diagnosis of the disease, but their results were indifferent, and since then 

 numerous writers have expressed various opinions as to the value of the 

 test. Garbat has secured uniform and reliable reactions with a poly- 

 valent antigen, and emphasizes the importance of this factor. 



