COMPLEMENT-FIXATION IN DOURINE 487 



Preparation and Standardization of Antigens. The antigen of 

 Bacillus abortus (Bang) for use in the complement-fixation test in 

 contagious abortion of cows is prepared by cultivating a number of 

 strains of the bacillus, which have been trained to grow aerobically, 

 upon slants of glycerin agar for seventy-two hours. The growths are 

 then washed off with sufficient normal saline solution containing 2 per 

 cent, phenol to yield a cloudy emulsion. Shake briskly in order to 

 break up the clumps of bacilli, and filter through paper. Place in a 

 refrigerator for several days to complete the sterilization, and titrate 

 the anticomplementary dose each time before the main test is conducted. 



The antigen may also be prepared by cultivating a number of strains 

 in glycerin-serum bouillon for five or six weeks. Centrifuge thoroughly 

 and wash the bacilli once or twice with normal saline solution, to remove 

 all traces of serum. Dilute the washed bacilli with sufficient normal 

 saline solution to give an emulsion equal in density to a twenty-four- 

 hour bouillon culture of Bacillus coli, and add 0.4 per cent, of phenol as a 

 preservative. 



The antigen of Bacillus abortus equi for making the complement- 

 fixation diagnosis of contagious abortion of mares is prepared of eigh- 

 teen- to twenty-hour-old glycerin bouillon cultures, with an addition 

 of 0.5 per cent, of phenol. These antigens are less anticomplementary 

 than shake extracts, and keep their titer unaltered for many weeks 

 (Meyer and Boerner). They may also be used for making the mac- 

 roscopic agglutination test. 



The anticomplementary dose is determined each time, and one-half 

 this amount is used in performing the main test. The technic is the 

 same as that employed in the titration of glanders antigen. 



The tests and controls are conducted with descending doses of fresh 

 inactivated serum (0.05, 0.1, and 0.2 c.c.), in exactly the same manner 

 as the glanders reaction is performed. 



COMPLEMENT FIXATION IN DOURINE 



Dourine, or horse syphilis, is a specific infectious disease of the horse 

 and ass, transmitted from animal to animal by the act of copulation, 

 and caused by the Trypanosoma equiperdum. It is characterized by an 

 irregular incubation period, the localization of the early symptoms to 

 the genital organs, and, finally, by complete paralysis of the posterior 

 extremities, a fatal termination ensuing in from six months to two years. 

 The disease is especially prevalent among horses in the northwestern 



