EXPERIMENT STATION BULLETINS. 461 



Triplicate cultures of each of the above described colonies were made in 

 pea agar shakes and a tube of each organism was placed at 55°, 37°, and 20°. 

 The growth was equally abundant at all three temperatures although slightly 

 slower at 20°. 



Growth in the pea agar shakes was well distributed throughout the tubes 

 in all cases. The medium throughout the whole tube became acid. In a 

 few days a slight surface growth appeared. The growth in all the tubes 

 looked very much alike. There was no gas formation. 



To make sure the cultures were pure the pea agar shakes were again plated 

 out in pea agar, aerobically. After incubation for twenty-four hours at 37°, 

 isolations were made in broth. 



Two general types of colonies were found which will be called A and B. 



Isolations from aerobic pea agar plates: 



A — Concentrically ringed colonies. 

 B — Smooth, round colonies. 



The types were found on the plates as indicated in this list: 



I— A, B. VI— A, B. X— Too thick. 



II— A, B. VH— B. XI— A, B. 



Ill— A, B. VIII— A, B. XII— Pure, neither A, B. nor C. 



IV-V— Sterile. IX— A, B. 



From the above organisms seven representative pure cultures were se- 

 lected for study because time was too limited for a study of the whole group. 



These organisms all form a thick, viscous, Avrinkled membrane on the 

 surface of the broth. 



Three clay broth cultures of these organisms were examined microscop- 

 ically with the following results: 



I. A. Long parallel filaments. Shorter ones actively motile. 



I. B. Motile rods, single and in chains. Growth not thick. 



VI. A and B. Like I B. 



VII. B. Like I B. Occasional long filaments. 



VIII. A. Like I. B. 



XI. A. Like I. B. 



Each of these organisms was inoculated into all the ordinary culture media. 

 In the study of these organisms determinations were made as follows : 



1 . Microscopic examination for vegetative cells on three day broth culture 

 grown at 20°C. 



2. Spore examination on twenty-one day broth culture grown at 20°C. 



3. Aqueous-alcoholic and gram stains on three day broth culture grown 

 at 20°. 



4. Thermal death point determination of twenty-one day broth culture 

 grown at 20°C. 



All media used had the reaction of +1-5. 



All cultures except gelatin stabs were kept at room temperature. The 

 gelatin stabs were kept at 15°C. 



