BACILLUS TYPHOSUS 



115 



it into suitable culture medium, and keeping it at body 

 heat in the incubator. If typhoid bacilli be present 

 they will grow so that we may isolate and identify 

 them. The bacilli may be isolated also from the 

 feces and urine during an attack, and as mentioned 

 above, for a long time afterward in the case of carriers. 

 The methods for isolation are tedious and difficult, 

 and need not be described here. Many techniques have 

 been devised to hasten work on epidemics and carriers, 

 but none is as yet very good. 



FIG. 35 



Typhoid bacilli from nutrient gelatin. X 1100 diameters. (Park.) 



Morphology. The typhoid bacillus is a motile rod 

 5-11-00- to s TO 0" inch long and 3- oi <ro to -^WiF inch wide, 

 with rounded ends, growing in long threads at times. 

 Its motility is due to flagella all around its cell wall. 

 It forms no spores. It stains easily, oftentimes more 

 densely at the rounded ends. It grows in the presence 

 or absence of oxygen, best at 37 C. or 98 F., but also 

 at room temperature. It is killed by heating at 60 C. 

 or 142 F. for five minutes, or to 52 C. or 126 F. for 



