268 MANUAL or BACTERIOLOGY. 



sible to say. In a work of this character it is feasible to men- 

 tion only a few of the commonest and best-known species 

 of non-pathogenic bacteria or such as have some marked 

 pecuHarity. 



Micrococcus Agilis. — ^Found in water; coccus about i ^ in 

 diameter, usually appearing as diplococci, sometimes as strepto- 

 cocci and tetrads; liquefies galatin slowly; grows at room tem- 

 perature, on ordinary culture media, forming a rose-red pig- 

 ment on agar and potato. This micrococcus is remarkable 

 in being actively motile; it possesses a fiagellum. It is stained 

 Gram's method. 



Micrococcus Urese.— Found in decomposed, ammoniacal 

 urine and in the air; coccus, 0.8 to i /^ 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 sarcinas. 

 They are common organisms in the air. They frequently con- 

 taminate plate-cultures. Many of the sarcinae of the air pre- 

 sent, in cultures, growths having brilliant colors, from which 

 some of them are named; thus there are arange, yellow, rose- 

 colored and white sarcinae, and others. 



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

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

 cells; aerobic; does not liquefy gelatin; grows slowly, best at 

 ordinary temperature, preferably upon gelatin. It decom- 

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

 endogenous spores which are extremely resistant toheat. 



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 



