614 



NON-PATHOGENIC MICROCOCCI. 



teriologists, but division in three directions, forming packets, has not been 

 observed. 



Stains with the usual aniline colors and by Gram's method. 



Biological Characters. An aerobic, liquefying, chromogenic micro- 

 coccus. Grows in the usual culture media at the room temperature. Colo- 

 nies in gelatin roll tubes are spherical, opaque, at first of a pale-yellow and 

 later of a lemon-yellow color ; . liquefaction around the colony usually does 

 not commence for several days and progresses slowly. In gelatin stick cul- 

 tures very scanty development occurs along the line of puncture, and the 

 gelatin is liquefied in cup shape by the surface growth ; at the bottom of the 

 liquefied gelatin a viscid, pale-yellow mass accumulates. Upon the surface 

 of agar a thick, viscid, yellow layer is formed along the impfstrich, which 



Fio. 206. Fia. 207. 



FIG. 206. Micrococcus tetragenus versatilia, from a single colony in nutrient gelatin. X 1,000. 

 From a photomicrograph. (Steinberg.) 



FIG. 207. Micrococcus tetragenus versatilis; culture in nutrient gelatin, end of two weeks at 

 22 C. (Sternberg.) 



gradually extends over the entire surface ; the color varies from cream-yellow 

 to lemon-yellow, and the surface is moist and shining. The growth upon 

 potato is similar to that upon agar. Not pathogenic for rabbits or guinea- 

 pigs. 



221. PEDIOCOCCUS ALBUS (Lindner). 



Found in well water. 



Morphology. Micrococci, solitary, in pairs, or in tetrads; frequently in 

 pseudo-sarcina accidental groups. 



Biological Characters. An aerobic, liquefying micrococcus. Grows in 

 the usual culture media at the room temperature. Is destroyed by a tem- 

 perature of CO C. in eight minutes. Upon gelatin plates forms spherical 

 colonies, around which liquefaction rapidly occurs, allowing the colonies to 

 fall to the bottom of the liquefied gelatin, where they form irregular flocculi. 

 In gelatin stick cultures, at the end of twenty-four hours, a deep channel of 

 liquefaction has already formed, at the bottom of which a white, loose sedi- 

 ment collects ; by the fourth day a pale-orange color is developed. Upon 

 the surface of agar a broad, dry layer forms along the impfstrich ; old cul- 

 tures have an orange color. Upon potato a dirty-white layer is developed. 

 Produces an acid reaction in culture media. , 



