416 PATHOGENIC MICROCOCCI 
of agar, at 37° C., a grayish-white or yellowish layer is formed at the end of 
twenty-four hours, which has a varnish-like lustre. Upon potato, at 30° to 
aA C., at the end of forty-eight hours a white or yellow layer has de- 
veloped. : . 
Pathogenesis.—According to Heydenreich, inoculations in rabbits, dogs, 
chickens, horses, and sheep cause a skin affection which is identical with 
that which characterizes Biskra button in man. When rubbed into the 
healthy skin of man it also produces the development of abscesses. 
MICROCOCCUS ENDOCARDITIDIS RUGATUS (Weichselbaum). 
Obtained by Weichselbaum (1890) from the affected cardiac valves in a 
fatal case of ulcerative endocarditis. 
Morphology.—Micrococci, resembling the staphylococci of pus in dimen- 
sions and mode of grouping; solitary, in pairs, in groups of four, or in ir- 
regular masses. 
Biological Characters.—An aérobic micrococcus. Does not grow at the 
room temperature. Upon agar plates, at 37° C., at the end of three or four 
days the superficial colonies consist of a small, brown, central mass sur- 
rounded by a granular, semi-transparent, grayish marginal zone; gradually 
they attain a characteristic wrinkled appearance; the deep colonies, under a 
low power, are irregular, finely granular, and contain a large central, yel- 
lowish-brown nucleus surrounded by a narrow, grayish-brown peripheral 
zone. Inagar stab cultures small, spherical colonies are formed upon the 
surface, which become confluent, forming a grayish-white, wrinkled layer 
which has a stearin-like lustre and is very viscid; a scanty growth occurs 
along the line of puncture. Upon potato, at 37° C., a scanty development 
occurs in the form of a small, dry, pale-brown mass. Upon blood serum 
isolated or confluent, colorless colonies are formed the size of a poppy seed; 
these are closely adherent to the surface of the culture medium. 
Pathogenesis.—W hen injected subcutaneously into the ear of a rabbit it 
produces tumefaction and redness; in guinea-pigs, formation of pus. When 
injected into the circulation of dogs, after injury to the aortic valves, an en- 
docarditis is developed. 
MICROCOCCUS OF GANGRENOUS MASTITIS IN SHEEP. 
Obtained by Nocard (1887) from the milk of sheep suffering from gan- 
grenous mastitis (mal de pis or d’araignée), a fatal disease which attacks 
especially sheep which are being milked for the manufacture of cheese, at 
Roquefort and elsewhere in France. 
Morphology.—Micrococci, solitary, in pairs, or in irregular groups, resem- 
bling the staphylococci of pus in dimensions and arrangement. 
Stains with the usual aniline colors and also by Gram’s method. 
Biological Characters.—An aérobic and facultative anaérobic, liquefy- 
ing micrococcus. Grows at the room temperature in the usual culture me- 
dia. Upon gelatin plates, at the end of forty-eight hours, the colonies are 
spherical and white in color; under a low power the superficial colonies are 
circular in outline, homogeneous, and brown in color; they are surrounded 
by a semi-transparent aureole ; liquefaction around the superficial colonies 
occurs sooner than around those beneath the surface of the gelatin. In 
gelatin stick cultures, at 18° to 20° C., on the second day liquefaction of the 
gelatin commences near the surface ; by the fifth day a pouch of liquefied‘ 
gelatin has formed, which has the shape of an inverted cone; at the bottom 
of this an abundant deposit of micrococci is seen, while the liquefied gela- 
tin above is clouded throughout. In agar stick cultures development oc- 
curs upon the surface as a thick white layer, which gradually extends 
over the entire surface, and after a time acquires a yellowish tint; develop- 
ment also occurs along the line of puncture. Upon potato a thin, viscid, 
grayish layer is peice developed; the outline is irregular and the edges 
thicker than the central portion ; the central portion of this layer gradually 
