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PATHOOENIC BACTERIA OF THE HUMAN MOUTH. 273

Subcutaneous applications from pure cultures of this bacter-
ium produced severe local inflammation and suppuration, and
in one case death by blood-poisoning, the bacteria being found
in large numbers in the blood and tissues.
Injections into the abdominal cavity of white mice and guinea-
pigs produced death in 60 per cent, of the cases, in twenty-two
hours to six days, from peritonitis. Bacteria could not be found
in the blood microscopically, but cultures made from the blood
of the heart developed pure cul-
tures of the bacterium injected. Kig. 117.
The fourth micro-organism
with pronoLinced pathogenic ac-
tion,

m. Bacillus pxlpce j?i/ogenes, W^^^WSW
was found in a gangrenous ^
tooth-pulp. It occurs as ba-
cilli, often slightly curved and
pointed, either singly, in pairs,
or in chains of four to eight
(Fig. 117, a). It grows moder- Bacillus pulp-e pyogenes.
Gelatine culture, 8 days old. a, single cells.
ately well in gelatine plate-
1100 : 1.
cultures, the colonies appearing
large and round, dark, yellowish brown, with distinct margins.
Line-cultures on gelatine begin to melt in eighteen to twenty-
four hours, up to that time appearing as grayish, shining lines,
slightly elevated above the surface of the gelatine, and about
1 mm. wide.
Line-cultures on agar-agar produce a moderately extensive
growth, bluish white, glistening by transmitted light, gray by
reflected light ; under the microscope granular, sometimes fibril-
lar in structure, gray, or in older colonies, yellowish.
Puncture-cultures in gelatine, eight days old, present the
appearance seen in Fig. 117, the gelatine melting with about
equal rapidity on the sides and in the middle of the tube. In-
jections of 0.05 into the abdominal cavity proved fatal to mice
in eighteen to thirty hours.
18