(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Pathogenic Bacteria"

HOG-CHOLERA.                           417

Linear cultures upon agar-agar present a translucent,
rather circumscribed, grayish, smeary layer.

Upon potato a yellowish coating is formed, especially
when the culture is kept in the thermostat

Bouillon made with or without pepton is clouded in
twenty-four hours. When the culture is allowed to stand
for a couple of weeks without being disturbed a thin
surface-growth can be observed.

Milk is an excellent culture-medium, but is not visibly
changed by the growth of these bacteria. Its reaction
remains alkaline.

The hog-cholera bacillus is a copious gas-producer,
capable of breaking up sugars into CO2, H, and an acid,
which, formed late, eventually checks its further devel-
opment. No indol and no phenol are formed in the
culture-media.

The bacillus is hardy. Smith found it vital after being
kept dry for four months. It ordinarily dies sooner, how-
ever. The thermal death-point is 54 C., maintained for
sixty minutes.

The bacillus is markedly pathogenic for animals.
Small quantities introduced subcutaneously into rabbits
or mice kill them in from seven to twelve days. The
animal appears quite well for three or four days, then
begins to sit quietly in the cage and eat but little, or
refuses to eat at all, until death takes place.

In Smith's experiments one-four-millionth of a cubic
centimeter of a bouillon culture injected subcutaneously
into a rabbit was sufficient to cause its death. Before
death the temperature abruptly rises 2~3 C., and re-
mains high until death. Larger quantities may kill in
five days. Injected intravenously in small doses the ba-
cillus may cause death in forty-eight hours.

When the animal is subjected to a postmortem exam-
ination the spleen is found enlarged, firm, and dark red
in color. The liver is found to contain small yellowish-
white necrotic areas which sometimes occur in one, some-
times in several acini, and not infrequently surround the

27