TYPHOID FEVER. 



343 



of aniline dyes, and grow well at the temperature of the room. In 

 plate-cultivations minute colonies are visible in thirty-six to forty- 

 eight hours ; they are circular or oval, with an irregular margin ; they 

 appear granular by transmitted light, and are yellowish-brown in 

 colour. Cultivated in the depth of gelatine a well-defined shiny film 

 forms at the point of puncture, and a greyish-white filament, com- 

 posed of closely packed colonies, develops in the track of the needle 

 (Fig. 134). On the surface of gelatine a greyish-white translucent 

 film forms, with sharply defined margin (Plate II., Fig. 2). On agar 

 there is a whitish transparent layer. They flourish in milk. On 

 potato at the temperature of the blood there is no culture visible, but 



FIG. 132. FLAGELLA OF TYPHOID BACILLI, x 1000, STAINED BY LOFFLER'S 

 METHOD (FRANKEL AND FFEIFFEB). ' 



the inoculated area appears moist and shining, and cover-glass pre- 

 parations made from the potato will demonstrate that there is really 

 a copious growth of the bacillus. This almost invisible growth is not 

 peculiar to this micro-organism. 



Whether this bacillus is really peculiar to typhoid is much dis- 

 puted. Bacilli very closely resembling it, if not actually identical, 

 have been found under other conditions. These pseudo-typhoid bacilli 

 are regarded by some bacteriologists as varieties resulting from the 

 different environment afforded by a saprophytic existence. Numer- 

 ous experiments have been made on animals with pure-cultures of 

 the bacillus, but in the production of typhoid fever they have 

 been no more successful than the experiments with typhoid stools. 



