Pathogenic Bacteria

ANTHRAX. 361

On potato the growth is white, creamy, sometimes
rather dry in appearance. Sporulation is marked.

Blood-serum cultures lack peculiarities; the culture-
medium is slowly liquefied.

The bacillus only grows between the extremes of 20°
and 45° C., best at 37° C. The exposure of the organ-
ism to the temperature of 42-43° C. for twenty-four hours
is sufficient to destroy its virulence.

The culture-media should always be faintly alkaline, as
anthrax bacilli will not grow in the presence of free acid.

The micro-organism under consideration is a parasitic
microbe, yet is one which, because of its spores, can, in
.a latent form, exist without the animal organism until
.appropriate conditions for its natural development are
presented.

Ordinarily, the infection takes place either through the
respiratory tract or through the alimentary canal.

Buchner has shown that when animals are allowed
to inhale anthrax spores they die of typical anthrax.
The spores establish themselves in the alveoli of the
lung, penetrate the epithelium, enter the vascular sys-
tem, and soon give rise to typical lesions. Strange to
say, the appearance caused by the inhalation of the
bacilli in their perfect form is entirely different, for a
rapid multiplication occurs without Sporulation, and
causes a violent irritative pneumonia with serous or sero-
fibrinous exudate in which large numbers of the bacilli
occur. In these cases there may be no general infection.

When the bacilli are taken into the stomach in food
they meet with a rapid death because of the acidity of
the gastric juice. Should spores, however, be ingested,
they are able to endure the gastric juice, to pass into the
intestine, and, as soon as proper conditions of alkalinity
are encountered, to develop into bacilli. They develop
rather rapidly, surround the villi with thick networks
of bacillary threads, separate the epithelial cells, enter
the lymphatics, and thus find the appropriate environ-
ment for the production of a general infection.