NON-PATHOGENIC BACTERIA. 221 



urine and in the air; coccus, 0.8 to i fj. in diameter, occurring 

 singly or in various combinations; does not liquefy gelatin; 

 facultative anaerobic; grows rapidly, best at 30^ to 33° C; 

 grows on ordinary gelatin, but best on special media; it de- 

 composes urea, producing ammonia and carbon dioxide, which 

 form ammonium carbonate. 



Sarcinae. — ^There is a large number of species of sarcinae. 

 They are common organisms in the air. They frequently 

 contaminate plate- cultures. Many of the sarcinas of the air 

 present, in cultures, growths having brilliant colors, from 

 which some of them are named; thus there are orange, yellow, 

 rose-colored and white sarcinae, and others. 



Sarcina pulmonum. — Found in the air-passages of man; 

 I to 1.5 p. in diameter, occurring in tetrads or cubes of eight 

 cells; aerobic; does not hquefy gelatin; grows slowly, best 

 at ordinary temperatures, preferably upon gelatin. It decom- 

 poses urine with the formation of ammonia. It is said to form 

 endogenous spores which are extremely resistant to heat. 



Sarcina ventriculi. — Found in the Stomachs of man and- 

 of animals; 2.5 /^ in diameter, occurring in cubes of eight 

 cells or more; it does not liquefy gelatin; aerobic; grows on 

 ordinary culture-media; the growths tend to become yellow. 

 Small numbers of sarcinae may occur in the normal human 

 stomach; the presence of large numbers indicates the existence 

 of abnormal fermentative processes. 



Bacillus fluorescens liquefaciens. — Found in water and 

 putrid fluids; very common; appears as a small rod, actively 

 motile; aerobic, but somewhat variably; liquefies gelatin; 

 grows rapidly at ordinary temperatures upon the usual cul- 

 ture-media. It forms a pigment having a beautiful greenish- 

 yellow fluorescence, best seen in transparent media; the growth 

 on potato has a brown color. Does not stain by Gram's 

 method and does not form spores. 



Bacillus fluorescens putidus. — ^Found in water; a short 



