CHAPTER XXX 



BACILLUS MUCOSUS CAPSULATUS, BACILLUS LACTIS AEROGENES, 



BACILLUS PROTEUS 



BACILLUS MUCOSUS CAPSULATUS 



(Bacterium pneumonice, Friedldnder' s bacillus, Pneumobacillus) 



IN 1882, Friedlander 1 announced the discovery of a microorganism 

 which he believed to be the incitant of lobar pneumonia and which, in 

 his original communications, he described as a " micrococcus." 



A superficial morphological resemblance between Friedlander's 

 microorganism and Diplococcus lanceolatus, now recognized as the most 

 frequent cause of lobar pneumonia, led, at first, to much confusion, and 

 it was not until several years later, owing to the careful researches of 

 Frankel 2 and of Weichselbaum, 3 that the " micrococcus " of Friedlander 

 was recognized as a short, encapsulated bacillus which occurred in 

 lobar pneumonia exceptionally only. Similar bacilli were subsequently 

 found by other observers, bacilli which, mainly upon morphological 

 grounds, are classified together as the "Friedlander group," or the 

 "group of Bacillus mUcosus capsulatus." 



Morphology and Staining. The Friedlander bacillus is a short, plump 

 bacillus with rounded ends, subject to great individual variations as to 

 size. Its average measurements are from 0.5 to 1.5 micra in width and 

 0.6 to 5 micra in length. Forms approaching both extremes may be met 

 with in one and the same culture. The short, thick forms, frequently 

 found in animal and human lesions, are almost coccoid and account for 

 Friedlander's error in first describing the bacillus as a ftiicrococcus. 

 The bacilli may be single, in diplo-form, or in short chains. They are 

 non-motile and possess no flagella. Spores are not formed. 



The bacillus is characteristically surrounded by a well-developed 

 capsule which is most perfectly demonstrated in preparations taken 

 directly from some animal fluid, such as the secretion or exudate 

 from infected areas. It is also seen, however, in smears made from agar 



* Friedlander, Virchow's Arch., Ixxxvii, 1882; Fort. d. Med., i, 1883; ibid., 

 ii, 1884. 



2 Frankel, Zeit. f. klin. Med., x, 1886. 

 Weichselbaum, Med. Jahrb., Wien, 1886. 



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