THE CLASSIFICATION OF BACTERIA l6l 



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,. 

 i-i.j 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 turbidi 

 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 i.j per cent normal HCl bouillon. Cultures .show no marked- 

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



Habitat. Soil. 



106. Bact. convolutum Wright 



B. convolutus 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, Hmited ; agar becomes greenish, 

 brown. 



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



Potato. Growth elevated. 



