HOG-CHOLERA. 419

blood of infected rabbits exposed to 58° C. This blood
was found to be exceedingly toxic.

DeSchweinitzl found that the introduction of progress-
ingly increased amounts of cultures into cows caused the
development in them of an antitoxic substance capable
of protecting guinea-pigs from the disease.

Working in my laboratory, Pitfield2 has found that
after a single injection of a sterilized bouillon culture of
the bacillus into the horse, the serum, which has origin-
ally slight agglutinative reactive power, is so changed as
to show a decided reaction. If the horse be immunized
to large doses of such sterile cultures, the serum reaction
becomes so marked that with a dilution of I : 10,000 a
typical reaction occurs in sixty minutes.

According to this experiment, in doubtful cases the
use of this reaction should greatly facilitate the differen-
tiation of the bacillus of hog-cholera from similar ba-
cilli.

1 CenlralbL /. Bakt. u. Parasitenk., xx., p. 573.

2 Microscopical Bulletin, 1897, p. 35.