668 NON-PATHOGENIC BACILLI. 



the margin becomes somewhat granular and jagged, while the centre re- 

 mains opaque; development and liquefaction of the surrounding gelatin 

 progress rapidly, so that the colonies soon coalesce. In gelatin stick cul- 

 tures development occurs along the entire line of puncture, and a broad 

 funnel of liquefied gelatin is formed in the course of a few days; this is 

 clouded and contains numerous flocculi ; later the surface is covered with a 

 a thin film, which sinks to the bottom when the test tube is shaken. Upon 

 the surface of agar development also occurs rapidly, forming a smooth, 

 shining layer on both sides of the impfstrich. In bouillon a diffuse cloudi- 

 ness is developed ; an abundant deposit collects at the bottom of the tube, 

 and a film is formed upon the surface. Upon potato a thick, flesh-colored 

 layer covered with protuberances and having a dull, moist surface. This 

 bacillus reduces nitrates with the production of nitric acid 



354. BACILLUS VERMICULARIS (Frankland). 



Found in water from the river Lea. 



Morphology. Bacilli with round ends, from 2 to 3 jn long and 1 u broad; 

 may grow out into ' ' worm-shaped " filaments. Upon potato oval spores are 

 formed; these are about 1.5 u long and 1 ju broad; they are formed in the 

 centre of the rods, and remain attached to each other in chains of consider- 

 able length. 



Biological Characters. An aerobic, liquefying bacillus. Exhibits os- 

 cillatory movements only. Forms oval spores. Grows slowly in the usual 

 culture media at the room temperature. Upon gelatin plates the deep col- 

 onies have a somewhat irregular 

 contour ; upon the surface flat colo- 



|^| r nies are developed, which have ir- 



J Q. ^K regular margins composed of wavy 



^ bundles of bacilli closely crowded 



together; the centre of the super- 

 ficial colonies is rough and wrinkled ; 

 later liquefaction slowly occurs and 

 Fio. 222. Bacillus vermicuiaris; a, from a ge- the colonies sink beneath the surface 



latin culture; b, spore-bearing filaments from of the gelatin. In gelatin stick cul- 



a potato culture, x i,ooo. (Frankland..) tares a moist, shining, gray layer 



with dentate margins is developed 



upon the surface ; this does not extend far from the point of puncture ; a 

 scanty growth is seen along the line of puncture; after some time the gela- 

 tin commences to liquefy beneath the surface growth. Upon the surface 

 of agar a smooth, shining layer of a gray color is slowly developed. In 

 bouillon the liquid remains clear, and a white, flocculent growth is seen 

 at the bottom of the tub. Upon potato a thick, flesh-colored layer with 

 irregular outlines. Eeduces nitrates to nitrites. 



355. BACILLUS NUBILUS (Frankland). 



Found in filtered London water. 



Morphology. Bacilli about 3 JLI long and 0.3 /n broad; solitary or in short 

 chains; grow out into long filaments in bouillon cultures these maybe 

 twisted in spiral form; upon potato the short bacilli are often curved, and 

 the long filaments may have a spiral form. 



Biological Characters. An aerobic and facultative anaerobic, liquefy- 

 ing bacillus. Exhibits rotatory movement's without change of location. 

 Spore formation not observed. Grows slowly at the room temperature in 

 the usual culture media. Upon gelatin plates the colonies are very charac- 

 teristic; at the end of forty -eight hours small clouded spots are seen, which 

 are not sharply defined ; under the microscope these are seen with difficulty 

 by transmitted light ; on the third day, when the-gelatin, commences to be 



