174 TYPHOID FEVER. 



spaces do not stain by any of the spore-staining processes, and 

 bacteria in which they are found are less resistant to external 



FIG. 63. FIG. 64. 



// 



Bacillus fyphosus, from culture Bacillus typhosus, showing flagella 



twenty-four hours old, on agar- stained by Loeffler's method. (Abbott.) 



agar. (Abbott.) 



influences than others. This bacillus has numerous fine, hair- 

 like flagella, which are not to be seen in unstained prepara- 

 tions or preparations stained by the ordinary methods, but 

 it requires the flagella-stain of Loeffler to bring them out. 



Biologic Characters. The Bacillus typhosus is aerobic, but 

 grows also without the presence of oxygen ; it is therefore 

 facultative anaerobic. It is non-spore-bearing, and is actively 

 motile, the motions at times being very rapid. It grows in 

 nearly all the artificial media, even at the room temperature, 

 but best at a temperature of 37 C. Its growth at 20 C. is 

 rather slow, but quite rapid at the temperature of the body. 



On gelatin plates its colonies appear as small, yellowish, 

 punctiforrn bodies, becoming in a short time round and 

 irregularly notched, resembling droplets of oil. In gelatin 

 stab-cultures they appear as small thick disks, finely dentated, 

 of a pearl-like color. They do not liquefy gelatin. 



On agar plates they appear as round, irregular, shiny colo- 

 nies of a blue or grayish-white color, and develop very abun- 

 dantly. In agar stab-cultures the growth is chiefly on the 

 surface, and in the depth of the medium there is scarcely any 

 appreciable development. 



