COMPLEMENT-FIXATION TEST IN TYPHOID FEVER 489 



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. Add 1J/2 or 

 2 units of antisheep amboceptor (determined by preliminary titration) 

 and 1 c.c. of 2.5 per cent, sheep's corpuscles. Incubate for one hour, 

 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. 



The antigen is prepared of numerous strains of typhoid bacilli the 

 more the better. Cultures are grown on slants of agar for forty-eight 

 hours, washed off with small quantities of sterile distilled water, heated 

 to 60 C. for two hours, shaken mechanically for twenty-four hours, and 

 either filtered through a sterile Berkefeld filter or thoroughly centrif- 

 ugalized. The filtrate is preserved with 0.5 per cent, phenol and used 

 as antigen. 



I have secured good results by removing the growths with small 

 amounts of normal salt solution, and placing them in a shaking flask, 

 and shaking for an hour to break up the clumps. After heating to 60 C. 



