PATHOGENIC BACTERIA. 315 



It stains with the ordinary aniline dyes, but does not stain by 

 Gram's method. It is aerobic and facultatively anaerobic. 

 It may be cultivated at ordinary temperatures, but grows 

 best at high temperatures. It does not liquefy gelatin. Stick- 

 cultures in gelatin develop a round, flat knob at the point where 

 the puncture enters the surface of the gelatin, making what is 

 called a a nail-shaped" growth; the growth in gelatin is white; 

 in old 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 coagu- 

 lated. It does not produce indol. 



The thermal death-point is about 56 C. moist heat. Strains 

 of this organism are 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 eyes, mouth, nose and ear; also bronchopneu- 

 monia, and more rarely empyema and meningitis. It was de- 

 scribed by Friedlander as the specific cause of lobar pneu- 

 monia; but more recent investigations indicate that it is com- 

 paratively seldom found in this disease. 



There are various capsulated bacilli (capsule bacilli of R. 

 Pfeiffer and others) which closely resemble the bacillus 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. 



Perkins,* as a result of his studies of this organism, comes 

 to the conclusion that there is no one organism entitled to the 

 name exclusively, but that the term includes a large number of 

 organisms which have been given various names. The only 

 method of differentiating the different members of the group is 

 by noting the fermentation reactions with sugars. He makes 

 three tentative groups. All carbohydrates fermented with the 



*Journ. Infec. Dis. Vol. I. 1904. pp. 241-267. 



