CHICKEN CHOLERA.	411
much more marked, so th^at the growth resembles a nail
with a pretty good-sized flat head. If, instead of a punc-
ture, the inoculation be made upon the surface of ob-
liquely solidified gelatin, a much more pronounced growth
takes place, and along the line of inoculation a dry,
granular coating is formed. This growth is quite similar
to that upon agar-agar and blood-serum, which growths
are white, shining, rather luxuriant, and devoid of char-
acteristics. No growth occurs in the absence of oxygen.
Upon potato no growth occurs except at the incubation
temperature. It is a very insignificant, yellowish-gray,
translucent film.
The introduction of cultures of this bacillus into the
tissues of chickens, geese, pigeons, sparrows, mice, and
rabbits is sufficient to produce fatal septicemia. Feeding
chickens, pigeons, and rabbits with material infected
with the bacillus is also sufficient to produce the disease
with pronounced intestinal lesions. Guinea-pigs usually
seem immune, though they succumb to very large doses,
especially when given intraperitoneally.
The autopsy shows that when the bacilli are intro-
duced subcutaneously a true septicemia results, with the
addition of a hemorrhagic exudate and gelatinous infil-
tration at the seat of inoculation. The liver and spleen
are enlarged; circumscribed, hemorrhagic, and infiltrated
areas occur in the lungs ; the intestine shows an intense
inflammation with red and swollen mucosa, and oc-
casional ulcers following small hemorrhagic spots. Peri-
carditis is of frequent occurrence. The bacilli are found
in all the organs. If, on the other hand, the disease has
been produced by feeding, the bacilli are chiefly to be
found in the intestine. Pasteur found that when pigeons
were inoculated into the pectoral muscles, if death did
not come on rapidly, portions of the muscle (sequestra)
underwent degeneration and appeared anemic, indurated,
and of a yellowish color.
The bacillus of chicken-cholera is one whose peculiar-
ities can be made use of for protective vaccination.