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PATHOGENIC BACTERIA OF THE HUMAN MOUTH. 263 ;
each other after fissation ; long pseudo-threads are, however, want-
ing. Specimens prepared from blood, as well as from cultures,
reveal bacilli with swollen extremities or irregular outlines (invo-
lution forms), here and there transformed into shapeless masses.
The bacilli are easily stained, and retain their color even after
the application of Gram's method. At a higher temperature
they appear to form spores.
" These bacilli may be cultivated on various nutrient media.
On gelatine-plates they form (after thirty-six hours) distinct
grayish- white dots, which soon rise above the surface and then
form large greenish-white, round, slimy drops, rising quite high
above the level of the gelatine. Under a weak power the
youngest colonies appear circular, of grayish-brown dark color,
and their entire surface covered with dark dots or with short,
dark lines and flourishes (Schnorkcln). Tlie larger superficial
colonies appear much lighter, irregularly outlined ; the surface
distinctly granular, especially at the margin.
"Puncture-cultures develop very quickly (in about twenty-
four hours), and show a typical nail-shaped growth. On potato
slices a thick, grayish- white, moist, shining coating is formed."
" Mice die about forty-eight hours after inoculation with small
quantities of the culture ; numerous bacilli are found in the
heart-blood and in all the capillaries, most abundantly in the
liver. Rabbits are not perceptibly affected by small inocula-
tions; but after intravenous injections of small doses they perish
from blood-poisoning within forty-eight hours, and show great
masses of bacilli in the blood.
" Large quantities of the culture injected into the veins caused
in rabbits, and in a more pronounced degree in dogs, diarrha'a,
sometimes bloody stools, and death within three to ten hours
the autopsy revealed also the characteristics of an acute gastro-
enteritis."

c. Staphylo^occas p^ojvnes aureus and alhus. Streptococcus
pyogenes.

It cannot for a moment ba doubted that these typically pyo-
genic organisms, which are very widespread in nature, fre-