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Full text of "Pathogenic Bacteria"

258                 PATHOGENIC BACTERIA.

itself so as to assume the form of a fragment of a tape-
worm. Upon agar-agar after the lapse of two days the
growth consists of a central pellicle along the line of in-
oculation, with little sprouts projecting in all directions
from the edges. The growth is grayish, with an occa-
sional yellowish tinge.

Punctures in agar-agar were unsuccessful, but in gela-
tin the appearance of the growth is similar to that of
the cholera spirillum.

The bacillus also grows upon potato in the form of an
elevated layer of exactly the same color as the potato.
In the course of time the entire potato becomes colored
a dark gray. It also grows in milk, urine, serum, and

The colonies of this bacillus are quite characteristic,
but so varied in appearance as to make one suspect that
the plate upon which which they grow is contaminated
with various other species of bacteria. In general, the
colonies may be said to appear slowly as transparent
-whitish drops, which become grayish and later yellow-
ish, and finally brownish in color. The gelatin about
them presents concentric, wave-like rings, depending
upon the liquefaction of the medicine.

When the growth is more rapid and occurs at higher
temperatures bundles of threads, somewhat resembling
the early stages of a mould, are observed. Examining
microscopically, one finds in the slowly growing colonies
a surrounding zone of small centrifugally arranged fine
threads or hairs extending in all directions, with one or
two exceptionally long bundles extending beyond the
others and beyond the limits of the colony. The long
threads are never found to divide. Many of the colonies
are highly suggestive of those of anthrax.

The bacillus is motile in very slight degree. It forms
spores. It is, in general, about the size of the tubercle

The vegetation of the organism is said to be peculiar
in that the bacillary stage is of short duration and soon