302 



MANUAL OF BACTERIOXOGY. 



not liquefied. Young surface colonies in gelatin appear whitish,' 

 with irregular borders and more or less wrinkled surfaces, when 

 shghtly magnified. It grows on the ordinary media, and the 

 growths are whitish. Bouillon is clouded. Milk becomes 

 sMghtly acid, but is not coagulated. In media containing dex- 

 trose, acid is formed but no gas. In lactose-bouillon neither 

 acid nor gas is formed, although when grown in milk the 

 typhoid bacilli produce an acid reaction. On the lactose-Ht- 





•J.^- 



V a . '^-N 



:i-«... 





^■.:'-[:'^-':-' ■■■■■■: 



'. <'-"v',- ..•'■ ■ '-■■ . .' . ■ vV. ■ '. • 



^- 'V'-^- -■■ ■ . ^'>■- t '■••> ' 



Fig. 91. — Bacillus of Typhoid Fever, Stained by Loffler's Method 

 TO Show Flagella. (X 1000.) 



mus-gelatin or agar of Wurtz the blue tinge possessed by colo- 

 nies of the typhoid bacillus on this medium is made use of 

 to distinguish them from colonies of the colon bacillus and other 

 bacteria which form acids from lactose. Neutral red has been 

 used in the same manner, as it is said not to be altered by the 

 typhoid bacillus, but to be changed by the colon bacillus to a 

 yellow color. This medium is prepared by adding to neutral, 



