438 



THE BACILLUS OF TYPHOID FEVER. 



fuchsin solution may be used. The sections should be washed in 

 distilled water only, when Ziehl's solution is used, or with a very di- 

 lute solution of acetic acid when Ehiiich's tubercle stain is employed 

 (Baumgarten). 



FIG. 108. Bacillus typhi abdominal! s, stained by Loffler's method, showing flagella. x 1,000. 

 From a photomicrograph by Frankel and Pfeiffer. 



Biological Characters. The typhoid bacillus is a motile, aero- 

 bic, non-liquefying bacillus, which grows readily in a variety of 

 culture media at the " room temperature/' Although it grows most 

 abundantly in the presence of free oxygen, it may also develop in its 

 absence, and is consequently a facultative anaerobic. 



In gelatin plate cultures small, white colonies are developed at 

 the end of thirty-six to forty-eight hours, which under the microscope 



are seen to be somewhat irregular in 

 outline and of a spherical, oval, or long- 

 oval form ; these have by transmitted 

 light a slightly granular appearance and 

 a yellowish-brown color. At the end of 

 three or four days the colonies upon the 

 surface of the gelatin form a grayish- 

 white layer of one to two millimetres in 

 diameter, with more or less irregular 

 margins, and, when developed from deep 

 colonies, with an opaque central nucleus. 



FIG. 109. Single colony of Bacillus rrn i ~u -j.i j T T-J. 



typhi abdominalis.in nutrient gela- These Colonies, by transmitted light, 



tin. (x?) From a photograph by have a yellowish-brown color towards 



the centre, where they are thickest, 

 while the margins are colorless and transparent ; the surface is com- 



