THE CLASSIFICATION OF BACTERIA i6l 



Gelatin colonies. Deep : in 2 days round irregular, nearly amorphous, 

 homogeneous or finely granular, grayish light yellowish ; border entire 

 finely filamentous. Surface: in 2 days round, thin, flat, veily disks, 

 1-1.5 mm. In 7-10 days round, entire, depressed, due to the liquefaction 

 of the gelatin. Microscopically, in 2 days round, entire, with a small, 

 dense, central nucleus, surrounded by a broad, thin, pale, homogeneous, 

 finely granular portion. In 7-10 days grayish, darker in centre, granular, 

 with concentric zoning ; border tuberculate ciliate ; other colonies show 

 an erose lobed border. Microscopic appearances rather variable. 



Gelatin stab. In depth, a filiform growth, becoming ciliate plumose. On 

 the surface, colony round irregular, thin, flat, entire lobate. In 7 days 

 a thin, flat, surface growth, under which is a crateriform shallow funnel- 

 formed liquefaction, which proceeds slowly. 



Agar slant. A thin, moist, glistening, translucent, spreading veil. 



Bouillon (neutral). A light uniform turbidity ; no pellicle. Remains turbid 

 after 5 weeks. 



Milk. After 7-10 days, rather thin, watery, with a slight brownish discolora- 

 tion, which, upon heating to boiling, gives a finely flocculent curd. 



Litmus milk. In 3-5 days, medium becomes a deep blue, with a strong 

 alkaline reaction. 



Potato. In 24 hours, a scarcely visible, dry, creamy streak, becoming, in 5 

 days, light pinkish, rather thick and raised, dry and dull. In 10 days, 

 color becomes a salmon-pink, later chocolate-brown. Indol negative. 

 Nitrates reduced to nitrites. 



No growth in 1.5 per cent normal HC1 bouillon. Cultures show no marked 

 odor. No gas in glucose bouillon, and no acid production. 



Habitat. Soil. 



106. Bact. convolutum Wright 



B. convolufus Wright : I.e., 461. 



Morphology. Bacilli large, occur singly and in pairs ; also twisted chains and 

 filaments. 



Gelatin colonies. Deep: round, dark, granular. Surface: round, grayish 

 white, translucent, woolly-looking, slightly opalescent, 2-4 mm. ; micro- 

 scopically, segmented fissured; edge irregular; darker centre. 



Gelatin stab. Liquefaction crateriform ; proceeds slowly. Medium alkaline. 



Agar slant. Growth translucent, grayish, limited ; agar becomes greenish, 

 brown. 



Bouillon. Turbid, with a pellicle ; medium becomes greenish. 



Potato. Growth elevated. 



