Cultivation 635 



Cultivation. The bacillus grows well upon all culture- 

 media under both aerobic and anaerobic conditions. 



Colonies. The deep colonies upon gelatin plates appear 

 under the microscope of a brownish-yellow color and spindle - 

 shape, and are sharply circumscribed. When superficial, 

 however, they become larger and form a thin, bluish, iri- 

 descent layer with notched edges. The superficial colonies 

 are often described as resembling grapevine leaves in shape. 

 The center of the superficial colonies is the only portion 

 which shows the yellowish-brown color. The. gelatin is not 

 liquefied. 



Gelatin Punctures. When transferred to gelatin punc- 

 ture cultures, the typhoid bacilli develop along the entire 



Fig. 222. Bacillus typhi abdominalis; superficial colony two days 

 old, as seen upon the surface of a gelatin plate. X 20 (Heim). 



track of the wire, with the formation of minute, confluent, 

 spheric colonies. A small, thin, whitish layer develops 

 upon the surface near the center. The gelatin is not lique- 

 fied, but is sometimes slightly clouded in the neighborhood 

 of the growth. 



Agar-agar. The growth upon the surface of obliquely 

 solidified gelatin, agar-agar, or blood-serum is not luxuriant. 

 It forms a thin, moist, shining, translucent band with smooth 

 edges and a grayish-yellow color. 



Potato. When a potato is inoculated and stood in the 

 incubating oven, the typical growth cannot be detected 

 even at the end of the second day, unless the observer be 

 skilled and the examination thorough. If, however, the 



