THE PNEUMO-BACILLUS 



413 



Cultural characters. The B. pneumonice is aerobic and 

 facultatively anaerobic, and may produce indole. It grows 

 readily on the various culture media from 20 to 37 C., 

 on agar and blood- serum forming a copious, viscid, greyish 

 growth ; on gelatin, a thick, white, shining, porcelain- like 

 growth without liquefaction ; 

 and in stab- cultures in gelatin 

 a so-called nail-shaped growth 

 is developed (Fig. 46), consist- 

 ing of a white growth along 

 the needle- track, tapering from 

 above downwards, and at the 

 surface heaped up and ex- 

 panded, forming the " head " of 

 the nail. On potato a copious 

 whitish growth develops, while 

 milk is curdled and gas- bubbles 

 frequently form in stab- gelatin 

 cultures. It is an active fer- 

 menter of carbohydrates ; the 

 fermentation reactions are given 

 in the Table, p. 381. 



Pathogenic action. The 



pneumo- bacillus of Friedlander FIG. 46. Friedlander's pneumo- 



is pathogenic to mice and bacillus ' Gelatin stab-cul- 



^ . & . ture, seven days old. 



guinea-pigs, but rabbits are 



immune. Post-mortem, the spleen is enlarged, the lungs 

 are congested and consolidated in patches, and the organism 

 is found in large numbers in the blood. In a small per- 

 centage of cases of croupous pneumonia Friedlander's 

 bacillus may be associated with the S. pneumonice. Fried- 

 lander's bacillus may sometimes set up a broncho-pneu- 

 monic or bronchitic process, and is occasionally associated 

 with anginal conditions, which are characterised by the 

 formation of a false membrane, with an absence of any 



