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multiply nor form spores, but is destroyed in 12 days at + 45º C.
whilst it lives for more than a mouth below + 17º C. MM. Cham-
berland and Roux have adopted the following method: aspirate char-
bonous blood into two tubes, fill them completely, close the ends with the
lamp, and then plunge them for an hour into a bath of water kept at
68º C.; then take them out and heat them a second time for an hour;
repeat this operation for five consecutive days; the blood so heated has
never given cultures when sown in suitable media, but its vaccinal
properties are weakened, and hence it is necessary to employ it in large
quantities. The liquid which flows from the clot from the tube
is used for inoculating sheep. Sheep which have received charbonous
blood which has been previously heated at 58º C. in sufficient quantity
inoculated into the cellular tissue, have resisted inoculation with the
strong virus; however, they have been rendered seriously ill by the
inoculation of control, which demonstrates that immunity conferred by
means of heated blood is less reliable than that brought about by the
attenuated virus. The amount of blood required to produce immunity
varies in different individuals; some have been protected by 8cc, and
others have not, even after the injection of 16cc to 32cc. Sheep
show themselves more refractory when they have received larger injec-
tions of heated blood. The immunity conferred by these methods is
not a lasting one, its duration being only for a few days; after a lapse
of 24 days it has been found that two out of every three animals have
lost the protection. Blood, prepared in the above manner and filtered,
was injected by MM. Chamberland and Roux into the vein of a sheep
in large doses. The sheep bore the injection of large quantities with-
out any sign of intoxication, but the immunity conferred was very
feeble, even less than that following subcutaneous inoculation, a fact
which might lead us to the conclusion that the vaccinal substances were
either eliminated by the kidneys or some other organ, or else partially
destroyed by oxidation. The injection of charbonous blood previously
filtered through porcelain has not succeeded in giving immunity to sheep
when inoculated into the veins. Might it not, from a consideration of
these facts, be inferred that the vaccinal material is a diastase, and
hence its alteration by heat and its not passing through a porcelain
filter.

Although charbon does not readily lend itself to a decisive demon-
stration of vaccination by chemical substances on account of the ease
with which the vaccinal material is changed by heat and re-agents, still
it remains certain that immunity can be conferred against charbon,
by means of blood deprived of bacilli, and it is the modified method
of Toussaint, by heating, which best shows it. Koch and Chamberland
consider that it is preferable to kill the microbes by the use of essences,