646 NON-PATHOGENIC BACILLI. 



rather rapidly at the room temperature. Spore formation not determined. 

 Upon gelatin plates forms white colonies with well-defined contour, from 

 one-quarter to one-half millimetre in diameter; by transmitted light these 

 are grayish-brown in color and present a slightly radial striped appearance. 

 Upon the surface of agar a dirty- white layer is developed. \Jponpotato a 



grayish-white, tolerably dry layer. In milk a slightly acid reaction is pro- 

 uced, and a very viscid substance having a peculiar odor is formed, espe- 

 cially in the lower portion of the liquid ; this can be drawn out into long 

 threads. 



302. BACILLUS AEROGEXES (Miller). 



Found in the alimentary tract of healthy persons. 



Morphology. Small bacilli of various lengths. 



Biological Characters. An aerobic, non-liquefying, motile bacillus. 

 Spore formation not observed. Grows at the room temperature. Upon 

 gelatin plates forms spherical, homogeneous, transparent, white or slightly 

 yellowish colonies ; older colonies sometimes appear to be formed of con- 

 centric rings. In gelatin stick cultures development occurs along the line 

 of puncture and the growth has a yellowish color; upon the surface a 

 thin, pearl-gray layer with dentate margins is formed ; in old cultures the 

 line of inoculation acquires a dark-brown color and is surrounded by a 

 pale-brown halo. Upon potato a dry layer of a dirty bluish-yellow color, 

 and with irregular outlines, is slowly developed. 



303. BACTERIUM AEROGEXES (Miller). 



Found in the alimentary tract of healthy individuals. 



Morphology. Short rods, solitary or in pairs. 



Biological Characters.^ An aerobic and facultative anaerobic, non- 

 liquefying, motile bacillus. Spore formation not observed. Grows at the 

 room temperature in the usual culture media. Upon gelatin plates forms 

 sharply denned, yellowish colonies, which are marked by dark lines radi- 

 ating from the centre toward the margin. In gelatin stick cultures devel- 

 opment occurs along the entire line of puncture and the growth has a brown- 

 ish-yellow color ; upon the sui'face a soft, flat, grayish- white mass is formed 

 about the point of puncture. Upon the surface of agar a soft, grayish- 

 white layer. Upon potato a soft layer with irregular margins and of a 

 slightly yellowish-white color. 



304. HELICOBACTERIUM AEROGEXES (Miller). 



Found in the alimentary tract of healthy persons. 



Morphology. Slender bacilli, solitary or in chains ; grow out into long, 

 undulating or spiral threads. 



Biological Characters. An aerobic, non-liquefying, motile bacillus. 

 Spore formation not observed. Grows in the usual culture media at the 

 room temperature. Upon gelatin plates forms transparent, white or slightly 

 yellowish colonies of various forms spherical, oval, snail-shaped, spindle- 

 shaped, spiral, etc. In gelatin stick cultures grows upon the surface as a 

 thin, bluish, scarcely visible, dry layer, which covers the entire surface at 

 the end of forty-eight hours; along the line of puncture a uniform, light- 

 yellowish growth. Upon agar the growth is not characteristic. Upon po- 

 tato a layer is formed which has a dry surface, indented margins, and a 

 yellowish-brown color. 



305. BACILLUS AQUATILIS SULCATUS xo. I. ( Weichselbaum). 



Found in the Vienna water supply. 



Morphology. Bacilli resembling" the bacillus of typhoid fe\erinform 

 and dimensions. 



