NON-PATHOGENIC MICROCOCCI. 605 



Biological Characters. Anaerobic, non-liquefyingmicrococcus. Grows 

 in the usual culture media best at the room temperature. Upon gelatin 

 plates the deep colonies appear as small, bluish-gray points; the superficial 

 colonies are at first small, bluish-gray discs, which later are irregular in out- 

 line ; at the end of five days they are about three millimetres broad and con- 

 sist of a central grayish- white disc surrounded by a bluish-gray ring with ir- 

 regular outlines. Under a low power the deep colonies are seen to be spherical 

 and granular, of a pale-brown or yellowish-green color, and in the interior 

 usually several concentric rings are observed; the superficial colonies show 

 in the interior a darker disc with irregular margins and marked by fine ra- 

 diating fissures ; around this is an irregular marginal zone of a pale-brown 

 color and granular in appearance, and this is enclosed in a white, shining 

 border. In gelatin stick cultures a thin, bluish-gray layer forms upon the 

 surface, which consists of a number of concentric rings of growth arranged 

 around the point of puncture as a centre. Upon agar a broad, smooth, shin- 

 ing layer with toothed margins and of bluish-gray white color. Oil potato 

 a thin, slimy, yellowish-gray layer. 



199. MICROCOCCUS CUMULATUS TENUis (Von Besser). 



Very common in nasal mucus of man. 



Morphology. Large oval cocci, associated in masses. 



Biological Characters. Anaerobic and facultative anaerobic, non-lique- 

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

 ture. In gelatin stick cultures grows along the line of puncture as a delicate 

 white stripe composed of small colonies ; upon the surface as a flat, trans- 

 parent layer with slightly elevated margins. Upon agar plates as thick, 

 transparent drops about 0.2 millimetre in diameter; under a low power 

 these are seen to have a large brown nucleus surrounded by a grayish-brown 

 zone having wrinkled margins ; later the colonies attain a diameter of 0. 5 

 centimetre, and appear as flat, transparent discs with a large central nucleus. 

 Scarcely any growth upon potato. In bouillon a considerable deposit accu- 

 mulates at the bottom of the tube, and the liquid is nearly transparent 

 above. 



200. MICROCOCCUS PLUMOSUS (Brautigam). 



Found in water. 



Morphology. Micrococci, 0.8 n in diameter, associated in zoogloea. 



Biological Characters. Anaerobic, non-liquefying micrococcvis. Grows 

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

 yellowish- white colonies are developed, which send out tongue-like processes 

 and the margins of which are abruptly thickened. In gelatin stick cultures, 

 from along the line of puncture, at certain points, long, delicate, white off- 

 shoots are given off into the gelatin, which resemble needle- like crystals; 

 similar offshoots from the layer upon the surface of the gelatin are also 

 seen ; these consist of cocci in masses, arranged like chains of pearls. Upon 

 potato an irregular, yellowish- white layer with tongue-like offshoots. 



201. MICROCOCCUS ROSETTACEUS (Zimmermaiin). 



Found in water. 



Morphology. Spherical or elliptical cocci, from 0.7 to 1 ft in diameter, 

 associated in grape-like masses. 



Biological Characters. An aerobic, non-liquefying micrococcus. Grows 

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

 the deep colonies are small, grayish-white, and usually spherical in form ; 

 under a low power they are sometimes seen to be lenticular or mussel - 

 shaped. The superficial colonies are rather broad, shining, yellowish-gray 

 drops, with more or less irregular outlines. In gelatin stick cultures a thin, 



