224 BACTERIOLOGY 



Agar slant. Growth composed of large rhizoid colonies. 

 Potato. Growth dirty white. 

 Habitat. Water. 



55- B. invisibilis Vaughan 



Am. Jour. Med. Sci., 1892, icy. 



Morphology. Bacilli large, ends rounded, 2-5 times their breadth. Grow 



at 37°. 

 Gelattn colonies. Pale yellow, burr-like, with irregular outlines. 

 Gelatin stab. A good growth in depth ; a scanty growth on the surface. 

 Agar slant. Growth thick, white, limited. 

 Potato. Growth invisible. Grow in Parietti's solution and in Uffelmann's 



gelatin. 

 Habitat. Water. 



56. B. venenosus Vaughan 



B. iienenosus-invisibilis Vaughan : Am. Jour. Med. Sci., 1892, 107. 

 Not clearly differentiated from the above. 



57. B. murinus 



B. of rat plague Issatschenko : Centralblatt f. Bakteriol., XXIII, 1898, 873. 



Morphology. Bacilli variable in size. Flagella peritrichic. 



Gelatin colonies. Round, brownish yellow, with coli-like structure. 



Gelatin stab. A good growth in depth, with outgrowths ; on the surface, a 



white layer. 

 Bouillon. A white scum and sediment. 

 Potato. Grows slowly, becoming in 6 days a bright yellow, scarcely visible 



layer. 

 Pathogenesis. Strongly pathogenic to rats and mice. By ingestion death of 



rats in 8-14 days ; of mice, in 4-8 days. Non-pathogenic to rabbits and 



pigeons. 

 Habitat. Isolated from the spleen and liver of rats attacked in St. Petersburg 



by a plague. 



58. B. denitrificans Burri-Stutzer 



B. denitrificans, I, Burri-Stutzer: Centralblatt f. Bakteriol., I, ate Abt., 189S, 356. 



Morphology. Bacilli ; on agar small rods, 0.5 : 0.5-1.0^ ; in bouillon, 1.0-2.5 /"• 



Motility rarely progressive. 

 Gelatin colonies. Deep: small, white, entire. Do not generally appear at 



the surface ; when they do they are soft, dry, with a translucent border, 



which is puckered and torn. 



