CHAPTER XVIII. 

 THE MUCOSUS CAPSULATUS GROUP. 



THE Mucosus CAPSULATUS GROUP. I Bacillus Ozscnse. 



Bacillus Rhinoscleromatis. I Bacillus Lactis Aerogenes. 



TEIE first member of the bacteria commonly known as the pneumo- 

 Bacillus Group or the Mucosus Capsulatus Group was isolated by 

 Friedlander 1 from pneumonic lungs. At that time he believed his 

 "pneumonia micrococcus" was the causative agent of lobar pneu- 

 monia, and it was so regarded until Frankel 2 and Weichselbaum 3 

 pointed out its comparative infrequency in lobar pneumonia, and 

 differentiated it clearly from the pneumococcus, the true etiological 

 organism of this disease. Weichselbaum also correctly interpreted 

 its morphology and conferred upon it the name Bacillus pneumonia?. 

 Subsequent investigations by many observers have added several 

 closely-related bacteria to the group which at the present time com- 

 prises the following somewhat imperfectly-differentiated types: 

 Bacillus mucosus capsulatus (Friedlander's pneumobacillus), Bacillus 

 rhinoscleromatis, 4 Bacillus ozrense, 5 Bacillus lactis aerogenes, 6 and 

 Bacillus acidi lactici. 7 



Morphology. The members of the Mucosus Capsulatus Group are 

 bacilli which vary in size and shape in the same culture from oval 

 almost coccoid elements to distinctly elongated rods. The limits of 

 size are comprised practically within the following dimensions: diam- 

 eter, 0.5 to 1.5 microns, length, 0.6 to 3.5 microns. They occur 

 typically singly or in pairs, less commonly united in short chains. 

 Motility is not observed in cultures of any members of the group and 

 they appear to be devoid of flagella. Spores have not been detected. 

 A well-defined capsule, readily demonstrable by capsule stains, sur- 

 rounds each organism if it is examined in tissues or secretions of the 

 animal body, or in albuminous media. It tends to disappear during 



* Virchows Arch., 1882, Ixxxvii, 319; Fort. d. Med., 1883, i, 719. 



2 Ztschr. f. klin. Med., 1886, x, 401. 



3 Wien. med. Jahrb., 1886. 



V. Frisch, Wien. med. Wchnschr., 1882, No. 32. 



6 Abel, Ztschr. f. Hyg., 1896, xxi, 89; Centralbl. f. Bakt., 1893, xiii, 161. 



6 Escherich, Darmbakterien des Sauglings, Stuttgart, 1886, p. 57. 



7 Hueppe, Deutsch. med. Wchnschr., 1884, p. 778. 



