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, 107. 



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



at 37 . 

 Gelatin 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. venenosus-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, 2te Abt., 1895, 356. 



Morphology. Bacilli ; on agar small rods, 0.5 : 0.5-1.0/n ; in bouillon, 1.0-2.5 /a. 



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. 



