THE COLON-TYPHOID GROUP 



137 



Bile Salt Media. Rapid growth without gas formation; a 

 number of special media suited for the growth of typhoid, 

 namely, Jackson's, Hesse, Hiss, Conradi-Drigalski, etc. (See 

 Water Analysis and formula for Media.) 



Stab-cultures. Mainly on the surface, a pearly layer. 



A gar Stroke Cultures. A transparent thick layer. 



Potato. The growth here is quite characteristic. At 37 

 C. in forty-eight hours a moist, transparent film is formed 

 over the whole surface, but so transparent that it can hardly 

 be seen without close observation. If a small portion of this 

 is placed under a microscope, it will be seen swarming with 

 bacilli (Fig. 60). 



The growth never becomes 

 more prominent; the potato 

 must have a neutral or acid 

 reaction. 



On Potato Gelatin. The colo- 

 nies do not have the yellow 

 color; they are transparent; 

 later on they become dark 

 brown with green iridescence. 



Milk. The bacteria grow 

 very well in milk, producing a 

 slightly acid reaction, but no 

 coagulation. 



Fermentation Tube. In sugar 

 broth, in the fermentation tube, acids are formed without gas. 



Glucose Gelatin. In glucose gelatin there is no gas-produc- 

 tion. Indol is likewise not generated by the typhoid bacillus, 

 whereas it is by the colon bacillus. 



Staining. Colored with the ordinary anilin dyes, when 

 they are warmed; since they are easily decolorized, acids 

 should be avoided. Gram negative. 



Distribution. Outside of the body it is rarely found. 

 Typhoid or enteric fever is a general infection, but affecting 

 chiefly the Peyer's patches of the intestine. The bacilli are 

 found in the intestinal glands and in the enlarged and deeply 



Fig. 59. Colonies of typhoid 

 bacilli three days old (Xioo) 

 (Frankel and Pfeiffer). 



