NON-PATHOGENIC MICROCOCCI. 595 



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

 room temperature. Upon gelatin plates forms lemon-yellow colonies, which 

 throw out tongue-like projections upon the surface of the gelatin and have 

 wave-like margins ; the surface is at first moist and shining, later cleft and 

 scaly In gelatin stick cultures development occurs along the line of punc- 

 ture and on the surface; liquefaction, beginning near the surface, progresses 

 slowly ; a yellowish layer floats upon the surface, and later settles to the 

 bottom of the tube. 



164. DIPLOCOCCUS CITREUS LIQUEFACIENS (Unna). 



Found on the skin of persons suffering from eczema seborrhoeicum. 



Morphology. Small, oval cocci, in pairs or in tetrads, often in irregular 

 groups or in short chains ; the diameter of a single element in a pair is 

 from 0.4 to 0.1 >. 



Biological Characters. An aerobic, liquefying, chromogenic micrococ- 

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

 gelatin plates, at the end of four days, the superficial colonies are grayish- 

 white, flat, circular discs the size of a mustard seed ; at the end of eight days 

 they are grayish-yellow, opaque, and about one to two millimetres in dia- 

 meter; at the end of two weeks they are lemon -yellow, concave, and begin 

 to sink into a shallow funnel of liquefied gelatin ; under a low power they 

 are seen to be finely granular. The deep colonies appear at first as white 

 points; under the microscope they are seen to be spherical or oval, brownish- 

 yellow, and have sharply defined outlines. In gelatin stick cultures, at the 

 end of six days, a thin, shining, yellowish layer has formed on the surface; 

 at the end of two weeks the gelatin is softened and a thick, yellowish- white, 

 flocculent deposit is seen, "while upon the surface of the liquefied medium 

 is an irregular, plate-shaped, deep lemon-yellow layer ; at the end of three 

 weeks the liquefaction has extended to a depth of about six millimetres ; the 

 liquefied gelatin is opaque and of a yellow color. Upon the surface of agar 

 a yellowish-brown layer with irregular margins is quickly developed; upon 

 potato, at the end of two weeks, a grayish-yellow layer. 



165. DIPLOCOCCUS FLAVUS LIQUEFACIENS TARDUS (Unna). 



Found upon the skin of individuals suffering from eczema seborrhoeicum. 



Morphology. Biscuit-formed diplococci, resembling the " gonococcus" ; 

 each element in a pair is from 0.5 to 0.8 /^ in diameter. 



Biological Characters. An aerobic and facultative anaerobic, liquefy- 

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

 room temperature very slowly upon gelatin and potato, more rapidly on 

 agar. Upon gelatin plates, at the end of eight days, the superficial colonies 

 are very small, circular, shining, pale grayish-yellow discs; at the end of 

 three weeks they are as large as a hempseed and of a chrome-yellow color; 

 later they become greenish-yellow and float in a circular zone of transparent, 

 liquefied gelatin. The deep colonies are at first punctiform ; later they are 

 small, opaque spheres of an olive brownish-yellow color. In gelatin stick 

 cultures a thin, yellowish-white, slimy layer is slowly developed upon the 

 surface ; at the end of three weeks this is from three to four millimetres 

 in diameter and irregular in outline ; as it becomes older the color is dark- 

 yellow or greenish-yellow ; a thin, yellowish growth develops along the line 

 of puncture ; at the end of four weeks the surface is depressed without being 

 really liquefied ; in eight weeks about half of the gelatin in the tube is lique- 

 fied and ti'anspareiit. The surface growth first floats upon the liquefied me- 

 dium ; later it settles to the bottom as a thick, flocculent, yellow deposit, 

 and the gelatin acquires a yellow color. Upon the surface of agar a thick, 

 slimy, yellowish white layer with wavy margins is developed ; later this has 

 a greenish-yellow color. Upon potato a sulphur-yellow layer is formed. 



