PATHOGENIC BACTERIA. 259 



cultures the various media acquire a brown color. Dextrose 

 and lactose are fermented by it; in cultures on potato, gas is 

 formed, causing a frothy appearance; milk is not coagulated. 

 It does not produce indol. 



The thermal death-point is about 56° C. It is pathogenic 

 for mice, less so for guinea-pigs and rabbits. This bacillus 

 is sometimes found in the healthy mouth and nose. It has 

 been known to cause inflammation, especially in the vicinity 

 of the mouth, nose and ear, bronchopneumonia, and more 

 rarely empyema and meningitis. It was described by Fried- 

 lander as the specific cause of lobar pneumonia; but more 

 recent investigations indicate that it is comparatively seldom 

 found in pneumonia. 



There are various capsulated baciUi (capsule bacilli of R. 

 Pfeiffer and others) which closely resemble the baciUus of 

 Friedlander, and at least belong to the same group. The 

 bacillus of ozena, which has often been found in that disease 

 is very similar. B. lactis aerogenes and B. coli communis 

 also have many points in common with the Friedlander bacillus. 



Bacillus of Rhinoscleroma. — ^A short bacillus with rounded 

 ends, often united in pairs, also growing to a greater length; 

 surrounded by a capsule; not motile; stained by the ordinary 

 aniline dyes. It is much like the bacillus of Friedlander, but 

 some writers state that it retains Gram's stain more tenaciously 

 than that organism; this may be doubted, however. The 

 organism has been cultivated. It is a facultative anaerobe. 

 It grows rapidly, best in the incubator. It does not liquefy 

 gelatin; its growth in gelatin stick-cultures resembles that of 

 the bacillus of Friedlander. It grows on the ordinary media. 

 Gas may be developed upon potato. 



It is pathogenic for mice and guinea-pigs, less so for rabbits. 

 Its virulence is less than that of Friedlander's bacillus. 



It has been obtained from the tissues of cases of rhinoscleroma. 

 Rhinoscleroma is a disease characterized by a chronic tuber- 



