PATHOGENIC BACTERIA. 265 



charges of children having cholera infantum. It appears 

 that this organism may occasionally be pathogenic to man, 

 causing pus-formation, peritonitis, and even general infec- 

 tion. 1 Cultures injected in considerable amounts may be 

 pathogenic to animals. 



Bacillus of Bubonic Plague. An oval or short rod- 

 shaped bacillus, with rounded ends, sometimes possessing 

 a capsule. It is not motile. It does not form spores. With 

 the aniline dyes the ends stain more deeply than the middle, 



FIG. 66. 



X. % % *<r 



^*> * 



* ju i 



Bacillus of Bubonic Plague. (Yersin.) 



called polar staining; by Gram's method it is decolorized. 

 It is aerobic. It grows at ordinary temperatures, but better 

 in the incubator. It grows on most media. The growths 

 are grayish-white. Gelatin and blood-serum are not lique- 

 fied. In bouillon, the medium remains clear, while a granu- 

 lar deposit forms on the sides and bottom of the tube. In 

 bouillon to which a few minute drops of sterile oil, as 

 cocoanut oil, have been added, a growth takes place from 

 the under side of the oil drops. Such growths extend down, 

 and are called stalactite growths. The stalactites break off, 

 with the slightest disturbance. 

 1 Ware, Annals of Surgery, Vol. XXXVL, 1902. 



