NON-PATHOGEXIC MICROCOCCI. 597 



169. MICROCOCCUS CREMOIDES (Zimmermann). 



Found in water. 



Morphology. Micrococci, about 0.8 n in diameter, arranged in grape-like 

 masses. 



Biological Characters. An aerobic, liquefying, chromogenic micrococ- 

 cus. Grows in the usual culture media at the room temperature. Upon 

 gelatin plates the deep colonies are small and yellowish- white in color; 

 under a low power they are seen to be spherical, granular, and yellow or 

 brownish-gray. Superficial colonies have an irregular, ' ' gnawed " margin, 

 and cause a saucer-like liquefaction of the gelatin, at the bottom of which a 

 yellowish- white mass, arranged in concentric rings, may be seen ; around 

 the margin delicate outgrowths into the unliquefied gelatin may be seen. In 

 gelatin stick cultures liquefaction occurs along the line of puncture in three 

 or four days; an air bubble is usually seen near the surface, and below this 

 an accumulation of a yellowish-white color; the liquefied gelatin below this 

 is transparent for some distance, and the bottom of the narrow channel is 

 again filled with a yellowish-white mass of micrococci ; at the end of a week 

 the liquefied channel measures about eleven millimetres at the surface and 

 a yellowish- white film floats upon the liquefied gelatin. Upon the surface of 

 agar a yellowish- white layer with irregular margins and a lustre like that 

 of amber is developed. Upon potato a tolerably abundant, cream-colored 

 layer extends over the surface. 



170. MICROCOCCUS ROSEUS (Eisenberg). 



Found in sputum of a patient with influenza. 



Morphology. Micrococci of 0.8 to 1 n in diameter, solitary or in irregular 

 groups. 



Biological Characters. An aerobic and facultative anaerobic, lique- 

 fying, chromogenic micrococcus. Grows in the usual culture media at the 

 room temperature, and at 37 C. without production of color. Upon gelatin 

 plates, at the end of three to four days, minute pink colonies are formed ; 

 later liquefaction commences about the colonies and progresses slowly. In 

 gelatin stick cultures development occurs slowly both upon the surface and 

 along the line of puncture ; the growth is at first colorless ; after three to 

 four days a small, round, pink layer is formed, which is depressed in the 

 centre ; at the end of a week the color resembles that of a red azalea blossom, 

 and liquefaction commences ; at the end of three weeks the gelatin is about- 

 half -liquefied and a pink sediment is seen. Upon the surface of agar, at 

 the room temperature, a soft, dark-pink layer is formed along the impfstrich 

 in two days ; at 37 C. a similar development occurs in twenty-four hours, 

 but without color. Upon potato, at the end of three to four days, a cherry- 

 red streak is seen along 1 the impfstrich ; this gradually becomes darker and 

 covers the entire surface ; the growth then resembles that of Bacillus pro- 

 digiosus. 



171. MICROCOCCUS AURANTIACUS (Cohn). 



Found in water. 



Morphology. Spherical or slightly oval cocci, 1.3 to 1.5 > in diameter, 

 solitary, in pairs, or in irregular groups. 



Biological Characters. An aerobic, non-liquefying, chromogenic mi- 

 crococcus. Grows in the usual culture media at the room temperature. 

 Upon gelatin plates spherical or elliptical colonies of an orange-yellow color 

 and smooth, shining surface. In gelatin stick cultures a small, button-like, 

 yellow growth develops upon the surface, and after a considerable time mi- 

 nute yellow colonies are seen along the line of puncture. Upon agar an 

 orange-yellow layer is formed, and upon potato a slimy, yellow growth. 



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