602 NON-PATHOGENIC MICROCOCCI. 



187. MICROCOCCUS AEROGENES (Miller). 



Found in the alimentary canal. 



Morphology. Large oval cocci. 



Biological Characters. An aerobic and facultative anaerobic, liquefy- 

 ing micrococcus. Grows in the usual culture media at the room tempera- 

 ture. Upon gelatin plates forms spherical colonies of dark color and smooth 

 contour. In gelatin stick cultures development occurs along the line of 

 puncture, with a brownish-yellow color, and a flat, button-like, grayish- 

 white, soft mass is formed upon the surface ; slight liquefaction occurs after 

 some days. Upon the surface of agar a yellowish-white, pap-like layer is 

 formed. The growth upon potato is similar to that upon agar. Possesses a 

 great resistance against the action of acids. 



188. MICROCOCCUS ALBUS LIQUEFACIENS (Von BeSSer). 



Very common in the nasal mucus of healthy persons. 



Morphology. Micrococci, about twice as large as Staphylococcus pyo- 

 genes albus, spherical or elliptical ; in irregular groups or in chains. 



Biological Characters. An aerobic and facultative anaerobic, liquefy- 

 ing micrococcus. Grows in the usual culture media at the room tempera- 

 ture. In gelatin stick cultures produces a stocking-shaped pouch of lique- 

 fied gelatin, and after a time complete liquefaction sometimes only pai'tial 

 and very tardy liquefaction. Upon agar plates white, shining colonies 

 with an elevation at the centre and of the margin, with a depression be- 

 tween, 0.5 centimetre or more in diameter; under a low power the centre 

 appears brownish and is surrounded by a dark zone, this py a more trans- 

 parent, grayish-brown zone, and finally by an opaque marginal ring. Upon 

 potato a shining, white layer is developed. 



189. MICROCOCCUS FCETIDUS (Klamann). 



Found in the posterior nares of man. 



Morphology. Micrococci of irregular dimensions, solitary, in pairs, in 

 short chains, or in irregular groups; the diplococci measure 1.4/* in dia- 

 meter. 



Biological Characters. An aerobic, liquefying micrococcus. Grows at 

 the room temperature in the usual culture media not so well in the incu- 

 bating oven. Upon gelatin plates oval or spherical white colonies are slowly 

 developed. In gelatin stick cultures a milk-white, shining, elevated mass, 

 with a knobby surface, is developed about the point of puncture ; later this 

 presents a central prominence surrounded by concentric circles and acquires 

 a brownish color ; liquefaction occurs slowly and the cultures develop a 

 disagreeable odor like that of ozaena. Upon the surface of agar a whitish, 

 irregular layer is slowly developed and extends over the entire surface. 

 Upon potato a slimy, irregular growth, of a pale reddish-gray color and a 

 knobby surface, which gives off an intense and disagreeable odor like that 

 of oza3na. 



190. MICROCOCCUS RADIATUS (Fliigge). 



Found in the air and in water. 



Morphology. Micrococci, from 0.8 to 1 /* in diameter, solitary, in short 

 chains, or in irregular groups. 



Biological Characters. An aerobic, liquefying micrococcus. Grows in 

 the usual culture media at the room temperature. Upon gelatin plates, at 

 the end of two days, white colonies with a yellowish-green shimmer, about 

 one millimetre in diameter, are developed ; under a low power these appear 

 yellowish-brown and have starfish-like outgrowths ; at the end of four days 

 a delicate, regularly -arranged, radiating aureole surrounds the colonies, out- 



