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2So                 PA THOGENIC BA CTERIA.

supply of oxygen contained in the blood, and we find
that they grow with great slowness, remain localized at
the seat of inoculation, and never enter the blood- or
lymph-circulation. Doubtless most cases of tetanus are
cases of mixed infection in which the bacillus enters with
bacteria, which greatly aid its growth by using up the
oxygen in their neighborhood. The amount of poison
produced must be exceedingly small and its power tre-
mendous, else so few bacilli growing under adverse con-
ditions could not produce fatal toxemia. The poison is
produced rapidly, for Kitasato found that if mice were
inoculated at the root of the tail, and afterward the skin
and the subcutaneous tissues around the inoculation were
either excised or burned put, this treatment would not
save the animal unless the operation were performed
within an hour after the inoculation.

Some incline to the view that the toxin is a ferment,
and the experiments of Nocard, quoted before the Acad-
emic de Medecine, October 22, 1895, might be adduced
in support of the theory. He says: u Take three sheep
with normal tails, and insert under the skin at the end
of each tail a splinter of wood covered with the dried
spores of the tetanus bacillus; watch these animals care-
fully for the first symptoms of tetanus, then amputate the
tails of two of them 20 cm. above the point of inocula-
tion, . . . the three animals succumb to the disease with-
out showing any sensible difference."

The circulating blood of diseased animals is fatal to
susceptible animals because of the toxin which it con-
tains; and the fact that the urine is also toxic to mice
proves that the toxin is excreted by the kidneys.

From pure cultures of tetanus bacilli grown in various
media, and from the blood and tissues of animals affected
with the disease, Brieger succeeded in separating two
alkaloidal substances—" tetanin '' and (c tetano-toxin,''
both very poisonous and productive of tonic convulsions;
and Brieger and Frankel later isolated an extremely poi-
sonous toxalbumin.