76 BACTERIOLOGY 



sunken in the liquefied gelatin ; microscopically, yellowish brownish 

 with a transparent border; slightly granular. 



Gelatin stab. Liquefaction begins in 2-3 days, becoming saccate ; gelatin 

 turbid, with a heavy sediment. 



Agar colonies. Deep colonies : round-oval, grayish yellow, opaque with a granu- 

 lar border. Surface colonies : round, moist, glistening, becoming several 

 millimetres in diameter, white ; microscopically, round, entire with a trans- 

 parent granular zone, and with a gray homogeneous centre. 



Bouillon. Turbid, a delicate pellicle, and a heavy white sediment. 



Milk. Coagulated. 



Potato. Growth limited, white, thick ; cultures have a pasty odor ; H 2 S pro- 

 duced ; indol in small amount. 



VARIETIES 



Staphlococcus epidermis-albus Welch : Am. Jour. Med. Sci., Phila., 1891, 439. 



Differs from No. 6 in the following points : Liquefies gelatin more slowly ; does 

 not quickly cause coagulation of milk, and is much less virulent when in- 

 jected into the circulation of rabbits. 



Habitat. Common on surface of body, and in the deeper parts of the 

 epidermis. 



Staphlococcus pyosepticus Hdricourt-Richet : Compt. rend. CVII, 1888, 690. 



Probably a variety of No. 6, but more pathogenic to rabbits, subcutaneous in- 

 oculations causing extensive inflammatory oedema, with death in 12-24 

 hours. 



7. M. mastitis . 



Micrococcus of Gangrenous Mastitis in Sheep, Nocard : 

 Annales Inst. Pasteur 1, 1887, 417. 



Morphology. Cocci solitary, in pairs and irregular clusters. Stain by Gram's 

 method. Facultative anaerobic. 



Gelatin colonies (surface). Round, white; microscopically, round, homo- 

 geneous, brown, surrounded by a translucent aureole. 



Gelatin stab. Liquefaction infundibuliform. 



Agar stab. A good growth in depth ; on the surface a thick white spreading 

 growth. 



Blood Serum. Liquefied. 



Potato. Growth thin, viscid, grayish ; central portion yellowish. 



Pathogenesis . Sheep inoculated subcutaneously in the mammary gland show 

 inflammatory oedema and death in 24-48 hours. Rabbits by subcutaneous 

 inoculation, show a local abscess. Guinea pigs immune. 



