BACTERIUM PNEUMONIAE. 225 



halensis ? The Bac. acidi Isevolactici resembles, morpho- 

 logically and biologically, the Bac. acidi lactici Hiippe, 

 but at room temperature only coagulates milk slowly (often 

 milk becomes a thick fluid only after twelve days), Avhile 

 in the incubator it coagulates milk rapidly. The acid 

 formed is levorotatory lactic acid. The coccus is pro- 

 vided with a thick capsule, liquefies gelatin, and forms 

 dextrorotatory lactic acid. During the final reading of 

 our proof-sheets, Leichmann, in a partial work, claims 

 to find in sour milk, besides his Bact. lactis acidi, also 

 the Bact. acidi lactici — in the layer of cream, often even 

 in preponderating number (C. B. L. v, 344). 



Special Culture Methods. — Ordinary gelatin or agar 

 plates do not give good results because of the minuteness 

 of the colonies. The best medium to employ is a chalk 

 medium (see Technical Appendix) which contains grape- 

 or milk-sugar. Upon this the colonies are surrounded by 

 a clear halo. Also good results are obtained with milk- 

 peptone gelatin. One pays attention to the small colonies. 



Bacterium pneumoniae. Friedlander.^ 



(Plate 15.) 

 Literature. — Friedlander (Fortschr. d. Med., Bd. I, 715, etc.). 



Synonyms. — Pneumonia bacillus of Friedlander, cap- 

 sule bacillus of pneumonia ; also compare pages 227 and 

 228. 



Microscopic Appearance. — Short rods (0.6-3.2^1 

 long, 0.5-0.8/-/. broad), with rounded ends. When from 

 the animal body, they present a thick gelatinous capsule, 

 which is developed only in milk among the nutrient 

 media. 



Spontaneous motility is absent. 



Staining Properties. — Stains by the usual methods 



' The Bact. tholoeideum Gessner is only differentiated by its effect 

 upon mice (A. H. IX, 129). Also the Bact. butyri colloideum Lafar 

 (C. B. XIII, 807), constantly present in butter, according to Lafar, 

 appears also related, although not yet sufficiently described biolog- 

 ically. 



15 



