482 



Pneumonia 



growing and more delicate pneumococcus. In the light of present 

 knowledge Friedlander's bacillus must be looked upon as the type 

 of a group of organisms (the "mucosus-capsulatus group") varying 

 among themselves in many minor particulars. The other members 

 of the group are Bacillus rhinoscleromatis {q.v.), and Bacillus 

 lactis aerogenes. 



Distribution. — The organism is sometimes found in normal saliva; 

 it is a common parasite of the respiratory apparatus; not infrequently 

 occurs in purulent accumulations; is occasionally found in feces, and 

 sometimes occurs under external saprophytic conditions. 



Morphology. — Though usuUy distinctly bacillary in form, the 

 organism is of variable length and when paired sometimes bears a 

 close resemblance to the pneumococcus of Frankel and Weichsel- 



Fig. 171. — Bacterium pneumoniae (modified after Migula). 



baum. It measures 0.5 to 1.5 ai in length. It frequently occurs 

 in chains of four or more elements and occasionally appears 

 elongated. It is these variations in form that have led to the 

 description of the organism by different writers as a coccus, a 

 bacterium, and a bacillus. It is commonly surrounded by a distinct 

 transparent capsule, hence its name " capsule bacillus " and Bacillus 

 capsulatus mucosus. The organism is non-motile, has no spores, 

 and no flagella. It stains well with the ordinary anihn dyes, but 

 does not retain the color when stained by Gram's method. 



Cultivation.— Colonies. — If pneumonic exudate be mixed with 

 gelatin and poured upon plates, small white' spheric colonies aj.pear 

 at the end of twenty-four hours, and spread out upon the surface of 

 the gelatin to form whitish masses of a considerable size. Under the 

 microscope these colonies appear irregular in outline and somewhat 

 granular. The gelatin is not liquefied. 



