Pathogenic Bacteria

460 PATHOGENIC BACTERIA.

The organism is widely distributed in nature, being
almost always present in garden-earth. It is also found
in various dusts, in the waste water from houses, and
sometimes in the intestinal canals of animals.

When introduced beneath the skin this bacillus proves
pathogenic for a large number of animals—mice, guinea-
pigs, rabbits, horses, dogs, sheep, goats, pigs, calves,
chickens, and pigeons. Cattle seem to be immune.

Giinther points out that the simple inoculation of the
bacillus upon an abraded surface is insufficient to pro-
duce the disease, because the oxygen which is, of course,
abundant there is detrimental to its growth. When an
experimental inoculation is performed, a small subcu-
taneous pocket should be made, and the bacilli introduced
into it in such a manner as not to be in contact with the
air.

If the inoculated animal be a mouse, guinea-pig, or
rabbit, in about forty-eight hours it sickens and dies.
The autopsy shows a general subcutaneous edema con-
taining immense numbers of the bacilli. In the blood
the bacilli are few or cannot be found, because of the
oxygen which it contains. The great majority of them
occupy the subcutaneous tissue, where very little oxygen
is present and the conditions of growth are therefore good.
If the animal is allowed to remain undisturbed for some
time after death, the bacilli spread to the circulatory sys-
tem and reach all the organs.

Brieger and Ehrlich have reported two cases of malig-
nant edema in man. Both cases were typhoid-fever
patients injected with musk, and developed the edema
in consequence of impurity of the therapeutic agent.
No case is reported, however, in which healthy men
have been infected with the disease.

Cornevin declares that the passage of the bacillus
through the white rat diminishes its virulence, and that
the animals of various species that recover from this
milder affection are subsequently immune to the virulent
organisms.