OZENA AND DISTEMPER 



503 



Preparation of suspensions for agglutination tests. Each or- 

 ganism was transplanted daily, on plain agar, for ten days; 

 twenty-four hour growths planted on plain agar in whiskey 

 flasks; incubated eighteen hours; growths washed off in physio- 

 logic salt solution plus 0.5 per cent formalin. The suspensions 

 were shaken for two hours; two days later tested for sterility; 

 then filtered three times through filter paper. Each was later 

 diluted with salt solution plus 0.5 per cent formalin to corre- 

 spond in density to our standard suspension of B. bronchisepticus, 



TABLE 2 



which contains about 2,000,000,000 organisms per cubic centi- 

 meter. Perfectly homogenous suspensions of all the strains used 

 were produced by this method. 



Agglutination tests. The serum was diluted with physiologic 

 salt solution and each tube contained 0.5 cc. suspension plus 0.5 

 cc. diluted serum. The tests were incubated at 37°C. and read- 

 ings made at the end of twenty-four hours. 



Tables 1, 2 and 3 show the results of the agglutination 

 experiments. 



