THE CLASSIFICATION OF BACTERIA 139 



40. Bact. tiogense (Wright) 



B. HogeHsis Wright : I.e., 441. 



Morphology. Bacilli medium-sized, plump ; occur singly, in pairs, short 



chains, and in filaments. 

 Gelatin colonies. Round, milk-white, elevated, 2 mm. ; microscopically, dark, 



opaque, with a greenish shimmer, becoming thinner, brownish, granular 



toward their margins. Grow in acid gelatin. 

 Agar slant. Growth grayish, glistening, rather limited. 

 Bouillon. Rendered turbid. 

 Potato. Growth gray-brownish, spreading. 

 Litmus milk. Decolorized ; reaction amphoteric. Indol doubtful. No 



growth at 37 C. 

 Habitat. Water. 



41. Bact. refractans (Wright) 



B. refractans Wright : I.e., 442. 



Morphology. Bacilli short, thick, medium-sized, in pairs or clumps. 



Gelatin colonies. In 2 days round, white, slightly elevated, 1.0 mm. ; micro- 

 scopically, brownish, segmented radially crimpled, with scalloped 

 outlines. 



Gelatin slant. Growth narrow, white, wrinkled. 



Agar slant. Growth thin, narrow, composed of translucent colonies. 



Pepton-rosolic acid. Unchanged or lighter in color. 



Bouillon. Slightly turbid, with a slight pellicle, and a sediment. 



Potato. Growth grayish brownish gray, composed of minute colonies. 



Litmus milk. Unchanged. Indol negative. Grow at 37 C. 



Habitat. Water. 



42. Bact. rodonatum (Ravenel) 



B. rodonatus Ravenel : I.e., 40. 



Morphology . Bacilli short ovals, rounded. 



Gelatin colonies. Deep : yellowish brown with irregular edges, and a rosette 

 structure. Surface: in 60 hours, 1.0 mm.; grow slowly with a rosette 

 structure, becoming distinctly petaloid on their edges ; reddish brown 

 centres and yellowish gray edges. 



Agar slant. Growth thin, white, translucent, limited. 



Gelatin stab. On the surface, growth thin, irregular, leafy, 4-5 mm. 



Potato. Growth moist, glistening, yellowish-brownish. 



Bouillon. Turbid, a thin pellicle. 



Pepton-rosolic acid. Decolorized. 



