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272 THE MICJiO-OROANISMS OF THE HUMAN MOUTH.
Puncture-cultures in gelatine, eight days old, have the appear-
ance seen in Fig. 115. The gelatine rapidly melts in form of a
funnel, while the masses of bacteria sink to the bottom, the
melted gelatine, however, remaining cloudy.
Injections of this bacterium into the abdominal cavity of white
mice produced death in ten to twenty-five hours. During their
sickness the mice sat drawn up, with bent back and eyelids
glued together. The autopsy showed peritonitis, and in some
cases purulent exudation. ]Micro-organisms were found only in
very small numbers in the blood.
Fio. llfi. Injections of 0.25 into the ab-
dominal cavity of rabbits and
guinea-pigs produced identical
results. Injections into the lung
produced death in less than
twenty-four hours. Subcutane-
^ ous inoculation (injections) of
mice resulted in extensive al)-
^ scess-formation.
U «
/. Bacillus dentalis viridans.
This organism was found in
Bacillus dentalis viridans.
the superficial layers of carious
Gelatine culture, 8 days old. a, single cells
dentine. It appears as slightly
1100 : 1.
curved, pointed rods, singly or
It grows well in plate-cultures at room
in pairs (Fig. 116, a).
the colonies under the microscope are nearly
temperature ;
colorless, having but a slight yellow tinge; they are perfectly
round, with a sharp contour, and show, when they do not lie too
close together, two or three concentric rings. This bacterium is
characterized by the production of a beautiful opalescent green
coloring-matter, which it imparts to the gelatine; the cell itself
is not colored.
Line-cultures on agar-agar produce a very thin growth, with
irregular margins, bluish by transmitted light, greenish gray by
reflected light, and colorless under the microscope.
Puncture-cultures on gelatine, eight days old, present the form
seen in Fig. 116.