418 EDWIN S. GOOD AND WALLACE V. SMITH 



Typical colonies were streaked on agar slants, some of which 

 were incubated by the Nowak method and others in the air. 

 At the end of twenty-four hours, no visible growth was noted 

 on the streak cultures incubated in the air. At the end of forty- 

 eight hours, however, some little growth could be detected even 

 with the naked eye, and at the end of seventy-two hours, quite 

 a luxuriant growth of the organism was obtained, in appearance 

 identical with streak cultures made with the B. abortus. On 

 examining the tubes which had been incubated under the Nowak 

 method, we found that they had made but slightly better growth 

 than those incubated in the air. Streaks on agar at room tem- 

 perature showed no growth in the time mentioned. We came 

 to the conclusion that if this organism was the B. abortus and grew 

 in the air after the first generation it was different from any we 

 had ever isolated. The organism responded to the following 

 tests in the following manner: It was found to be non-motile; 

 gram negative; did not produce gas in either lactose or glucose; 

 did not coagulate milk; grew readily in plain bouillon, showing 

 a fair degree of cloudiness at the end of seventy-two hours; 

 and did not liquefy gelatin. Serum-agar tubes heavily inoculated 

 with this organism and quickly solidified in ice water and in- 

 cubated in the air, developed a growth characteristic of the B. 

 abortus, as noted by this laboratory, in that a narrow ring of 

 growth appeared as a slight haze 3 mm. beneath the surface of 

 the medium at the end of sixty hours, and eventually extended 

 to the top of the medium. All the above tests conform to the 

 biological and cultural characteristics of the Bang bacillus. 



We were not, however, satisfied that the organism isolated 

 was the Bacillus abortus on account of its growing in the air 

 so readily, so we subjected the culture to the agglutination and 

 complement fixation tests, using the serum from a rabbit made 

 immune to the Bang bacillus, which agglutinated in high dilu- 

 tions. It was found that this serum agglutinated our organism 

 in a dilution of 1:1200, which was exactly the same dilution in 

 which the serum agglutinated an antigen made of a well known 

 strain of the B. abortus, which had been obtained from an abort- 

 ing cow. Using as an antigen the organism isolated from the 



