LYSINS 169 
TJie Diagnosis of (llauders by the Method of Comylement-fixatioii.— 
The antigen is prepared from glycerin-agar cultures^ of se\eral strains 
of B. mallei incubated at 37° (\ for forty-eight hours. The organ- 
isms are autolyzed in distilled water for several hours at a relatively 
high temperature (70° to 80° C.) then freed from suspended particles 
by filtration through coarse Berkefeld filters. The filtrate is stored in 
amber bottles in the ice-box after the addition of 0.5 per cent phenol. 
The anticomplementary titer is determined from a series of tubes 
containing constant amounts of complement and graduated amounts 
of antigen (1 to 20 dilution in salt solution) .^ The total volume of 
complement and antigen is brought to 3 cc. by the addition of salt 
solution. After one hour's incubation in the water-bath at 37° C, 1 
cc. of sheep erythrocyte suspension and 1.5 units sheep erythrocyte 
hemolysin are added and reincubated. That dilution of antigen 
which shows the slightest inhibition of hemolysis is taken as the anti- 
complementary titer of the antigen. Not more than one-half this 
amount, and preferably one-fourth of the anticomplementary titer, is 
used in the test. 
The actual determination is made in the same manner as for the 
Wassermann test.'^ It is well to include a known positive and known 
negative glanders serum of the same animal species as the imknown, 
together with suitable controls of the hemolytic system. The length 
of incubation is determined by the time it takes to effect complete 
hemolysis in the known negative and the hemolytic controls. Fre- 
quently ten or more hours will elapse before this occurs. 
The Diagnosis of (ionorrhea by the Method of Complement-fixation.— 
Several strains of the organism must be used. The gonococcus 
autolyzes readily, hence a suspension of proper density (2.5 to 5,000,- 
000,000 per cc.) in freshly sterilized salt solution (8.5 gm. per liter) will 
usually yield an excellent antigen after twenty-four hours, at 37° C. 
The material should be passed through a Berkefeld filter, and the fil- 
trate retained. The procedure is the same as for glanders. 
The Wassermann test and its several modifications as applied to the 
diagnosis of syphilis, has been of incalculable value to medicine. The 
method, however, is complicated, and except in skilled hands, difficult 
to execute. Grave injustice may be done by an inaccurate test. 
Medicine has long hoped for a relatively simple, reliable procedure to 
supplant the Wassermann test. The Kahn test, named in honor of 
Dr. Reuben Kahn, who has perfected it, has stood the exacting scrutiny 
of some quarter of a million comparisons with the Wassermann pro- 
cedure, in many laboratories, very successfully. It combines the three 
prime requisites of relative simplicity, accuracy, and speed in high 
degree. It has supplanted the older methods in many laboratories, 
1 Reaction 1.5 per cent acid to phenolphthalein. 
2 Usually a range of antigens from 2 cc. to 0.05 cc. will be found sufficient. 
' For full discussion of results, see Mohler and Eichhorn: Bureau of Animal Industry 
Bulletin 136, April 7, 1911. 
