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 Ehrlich’s tubercle stain is employed 
(Baumgarten). 
Fig. 108.—Bacillus typhi abdominalis. stained by Liffler’s method, showing flagella. x 1,000. 
From a photomicrograph by Frankel and Pfeiffer. 
Biological Characters.—The typhoid bacillus is a motile, aéro- 
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 anaérobic. 
In gelatin plate cultures small, white colonies are developed at 
the end of thirty-six to forty-eight hours, which under the microscope 
Fig. 109,—Single colony of Bacillus 
typhi abdominalig, jn nutrient gela- 
tin. (x?) From a photograph by 
Roux. 
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. 
These colonies, by transmitted light, 
have a yellowish-brown color towards 
the centre, where they are thickest, 
while the margins are colorless and transparent ; the surface is com- 
