Pathogenic Bacteria

422 PATHOGENIC BACTERIA.

In general, its appearance -in culture-media is very
similar to that of the bacillus of hog-cholera. Kruse,
however,1 points out that when the bacillus grows in
bouillon the liquid remains clear on account of the for-
mation of a flocculent, stringy sediment. Upon ordi-
nary acid potato the bacillus does not grow, but if the
reaction of the medium be alkaline a grayish-yellow patch
is formed. In its growth in milk slight acidity is pro-
duced, but the niilk is not coagulated and the litmus
color added to it is not decolorized.

The bacillus stains by the ordinary methods, some-
times only at the poles, then resembling very closely the
bacillus of chicken-cholera. It is not colored by Gram's
method.

The pathogenesis, while similar to that of the hog-
cholera bacillus, presents some marked differences, espe-
cially in regard to the seat of the local manifestations,
to which attention has already been called, and in the
duration of the disease, which is much shorter. There
is also considerable resemblance to the bacillus of chicken-
cholera in pathogenesis, but the local reaction following
injection of the culture partakes of the nature of a hemor-
rhagic edema, which is not present in chicken-cholera, and
the cases often exhibit fatty metamorphosis of the liver.

Rabbits, mice, and small birds are all very susceptible
to the disease, generally dying of septicemia in twenty-
four hours; guinea-pigs are less susceptible, except the
very young animals, which die without exception. Chick-
ens are more immune, but usually succumb to large doses.
Hogs die after subcutaneous injection of the bacilli, and
suffer from marked edema at the point of injection, and
septicemia. If injected into the lung, a pleuropneumonia
with multiple necrotic areas in the lung follows. In
these cases the spleen is not much swollen, there is slight
gastro-intestinal catarrh, and the bacilli are present every-
where in the blood.

Animals cannot be infected by feeding.

1 Flugge's Mikroorganismen, p. 419, 1896.