318 BACTERIOLOGY 



Gelatin stab. Old cultures show on the suifcce a white expansion, becoming 

 violet-blue; after a time the growth sinks, and the gelatin becomes slowly 

 liquefied. Freshly isolated cultures may show a funnel-formed-cylindrical 

 liquefaction, whose contents are gray violet. 



Agar slant. Growth moist, glistening, yellowish brownish white, becoming 

 deep violet. 



Potato. Growth violet violet-black, spreading. 



Bouillon. Turbid, with a membrane, slightly violet. 



Milk. Slowly coagulated, ordinarily not coagulated ; colored violet, at least 

 the cream layer. 



Glucose bouillon. Slightly acid ; no gas. H. 2 S produced. Jndol produced. 



Habitat. Water. 



23. Ps. ccerulea (Voges) 



B. ca-ru/eus Voges: Centralblatt f. Bakteriol., XIV, 1893, 303. 



Morphology. Bacilli 0.8: 1. 0-1.4 p. One polar flagellum. At 37 good 



growth, with pigment production. 

 Gelatin colonies. Typhoid-like, becoming grayish blue ; slowly liquefied. 

 Gelatin slab. Slight growth. 

 Bouillon. A gray membrane on the surface. 

 Milk. Coagulated ; the cream layer sky-blue. 

 Potato. Growth grayish blue blue green, becoming darker, coarsely 



granular. 

 Habitat. Water. 



24. Ps. Smithii 



B. cceruleus Smith: Med. News, II, 1887, 758. 



Morphology. Bacilli 0.5 : 2.0-2.5 i frequently form leptothrix-like threads. 



Gelatin colonies. Form cup-like liquid depressions. No color in the depth 

 of the gelatin, but the surface colonies exhibit a faint blue tint. 



Gelatin stab. A funnel ; in depth, a few colonies. 



Agar slant. Growth bluish. 



Potato. Growth dark blue, becoming intense blue black. According to 

 Wright (I.e., 450- 



Gelatin colonies. Deep : irregular oval, finely granular, yellowish-brownish. 

 Surface: thin, translucent, slate-blue ; microscopically, finely granular, 

 with irregular outlines. Later the surface colonies are bluish gray 

 masses within depressions of liquefied gelatin which microscopically are 

 dense, brown, opaque, coarsely granular, with ragged margins. 



Gelatin stab. Liquefaction napiform, with a bluish gray membrane and a 

 bluish sediment ; little growth along the line of stab. 



