314 MANUAL OF BACTERIOLOGY. 



seldom forming threads. Most observers have found it non- 

 motile. Vedder and Duval have demonstrated flagella. The 

 bacillus does not form spores. It may be stained with the 

 ordinary aniline dyes; it does not stain by Gram's method. 

 It is facultative anaerobic. It grows at ordinary tempera- 

 tures, but better in the incubator. It grows on the usual 

 culture-media, but more slowly than B. coli communis. 

 The growths are whitish. Colonies on gelatin plates re- 

 semble those of the typhoid bacillus. Bouillon is diffusely 

 clouded ; a precipitate may form, but no pellicle. Indol is 

 not produced. Milk becomes acid and is not coagulated. 

 On potato a thin pale layer forms which may become light 

 brown. No gas is formed in media containing glucose or 

 lactose. 



Xeutral-red agar is not changed. From the feces the 

 bacillus is best cultivated on agar plates, in the incubator. 

 Colonies of B. coli communis are often more numerous 

 than those of the dysentery bacillus. The colonies which 

 develop in twenty-four hours are likely to be colonies of 

 B. coli communis. Their position may be marked on the 

 glass with a pencil. Those which appear later are to be 

 planted in dextrose-agar. If gas develops they are not the 

 bacillus of dysentery; otherwise they are to be studied and 

 identified by the cultural and other tests mentioned above, 

 and by the agglutination reaction. 



The bacilli are destroyed in a few minutes by boiling, and 

 at 58 C. in half an hour. They appear not to be particularly 

 resistant to the influences that are harmful to bacteria in 

 general. 



They have been found in the intestine and the discharges 

 of acute and epidemic dysentery in various climates and 

 countries, including the United States. Thus far their dis- 

 semination in the blood and distant organs has not been 

 demonstrated. The lesion of this form of dysentery con- 



