PATHOGENIC BACTERIA. 371 



whitish, with irregular borders and more or less wrinkled 

 surfaces, when slightly magnified. It grows on the ordinary 

 media, and the growths are whitish. Bouillon is clouded. 

 Milk becomes slightly acid, but is not coagulated. In media 

 containing dextrose, acid is formed but no gas. In lactose- 

 bouillon neither acid nor gas is formed, although when grown 



FIG. 96. Bacillus of typhoid fever, stained by Loffler's method 

 to show flagella. (X 1000.) 



in milk the typhoid bacilli produce an acid reaction; but this 

 acidity is not due to a fermentation of the milk-sugar, but to a 

 substance resembling glucose as was pointed out by Theobald 

 Smith. 



In Dunham's peptone solution indol is not formed in one or 

 two days, but in cultures grown for 10 days at 37 C. there is 

 always indol formed,* as a rule. 



On the lactose-litmus-gelatin or agar of Wurtz the blue tinge possessed by 

 colonies of the typhoid bacillus on this medium is made use of to distinguish 



*Chantemesse, Morris (Quoted from Gunther Loc. cit. p. 526). 



