418 PATHOGENIC MICROCOCCI 



nute, spherical, semi-transparent colonies are developed among- the impfstrich ; 

 these have a bluish tint by reflected light ; they may become confluent, form- 

 ing a thin layer with well-defined margins. Upon gelatin plates, at 16 to 

 18 C., colonies are first visible at the end of two or three days; they are 

 spherical and slightly granular, at first transparent and later of a pale-yellow 

 color by transmitted light, which gradually becomes brown. At the end of 

 five or six weeks the colonies are still quite small, well defined, and opaque. 

 Pathogenesis. Pure cultures injected into the mammary gland of cows 

 and goats gave rise to a mastitis resembling in its development that from 

 which the streptococcus was obtained in the first instance. Injections into 

 the cavity of the abdomen or into a vein, of one cubic centimetre of a pure 

 culture, gave a negative result in dogs, cats, rabbits, and guinea-pigs. 



DIPLOCOCCUS OF PNEUMONIA IN HORSES. 



Obtained by Schiitz (1887) from the lungs of horses affected with pneu- 

 monia. 



Morphology. Oval cocci, usually in pairs, surrounded by a homogene- 

 ous, transparent capsule. 



Does not stain by Gram's method. 



Biological Characters. An aerobic, non-liquefying micrococcus. Grows 

 at the room temperature. Upon gelatin plates forms small, spherical, white 

 colonies. 



In gelatin stick cultures grows along the line of puncture as small, white, 

 separate colonies, which grow larger without becoming confluent. Upon 

 the surface of agar small transparent drops are developed along the impf- 

 strich. 



Pathogenesis. The injection of a pure culture into the lung of a horse 

 produces pneumonia and causes its death in eight or nine days. Pathogenic 

 for rabbits, guinea-pigs, and mice. 



STREPTOCOCCUS CORYZ^E CONTAGIOS.E EQUORUM. 



Obtained by Schiitz (1888) from pus from the lymphatic glands involved 

 in horses suffering from the disease known in. Germany as Druse des 

 Pferdes. 



Morphology. Oval cocci, in pairs, in chains containing three or four 

 elements, or in long chaplets. 



Stains with the usual aniline colors very intensely with Weigert's or 

 Ehrlich's solution. 



Biological Characters. An aerobic and facultative anaerobic micrococ- 

 cus. Grows slowly at the room temperature, more rapidly at 37' C. Upon 

 gelatin plates at the end of three to five days minute colonies become visible ; 

 these never exceed the size of a pin's head. In gelatin stab cultures growth 

 upon the surface is scanty or absent; along the line of puncture minute 

 colonies are developed in rows. Upon agar plates, at 37 C., at the end of 

 twenty four hours lentil-shaped colonies are developed the size of a pin's 

 head ; under a low power the superficial colonies are seen to have a well-de- 

 fined, opaque nucleus surrounded by a grayish, transparent marginal zone, 

 which represents a half -fluid, slimy growth which does not extend after the 

 third day and later disappears entirely; the deep colonies are at first well- 

 defined, and later surrounded by wing-like outgrowths. Upon blood serum, 

 at 37 C., yellowish, transparent drops are first developed; these become con- 

 fluent and form a viscid and tolerably thick layer; this later becomes dry 

 and iridescent. 



Pathogenesis. Pathogenic for horses and for mice, producing in these 

 animals an abscess at the point of inoculation, and metastatic abscesses in 

 the neighboring lymphatic glands. Not pathogenic for rabbits, guinea-pigs, 

 or pigeons. 



