la bière, and his contests with his opponents, he came
out well equipped, with a perfected technique, and a
knowledge both of bacterial species and of how to grow
them. To solve all these problems he could draw only
from his own depths, and this he showed at once.

Old observations and experiments had taught him
that the blood of a sound animal, taken as it circulates
in the veins and exposed to air which is free from germs,
does not putrefy at the highest temperatures, nor give
birth to any organism. It seemed to him probable,
therefore, for he knew nothing then of the cultural ex-
periments of Delafond and of Koch, that the blood of
an animal infected with anthrax, if sown in a suitable
medium, would stock it solely with anthrax bacilli which
he could then keep pure for an indefinite time in suc-
cessive cultures, as he had done with yeast and other
ferments.

Experiment proved it to be so, and showed that this
bacteridium multiplies abundantly in urine made neu-
tral or slightly alkaline. From that time, the problem
was solved. Let us take a series of cultures of this
bacteridium transferring each time one drop from the
preceding culture into 50 cc. of fresh urine. The first
dilution is 1/1000, the second 1/1,000,000, the third
1/1,000,000,000, etc. After ten cultures it falls to
such a figure that the original drop of blood which
furnished the first sowing, has been, so to speak, drowned
in an ocean. Everything that it carried with it, to
which we might be tempted to attribute a rôle in the
production of anthrax--red corpuscles, white corpuscles,
granules of all sorts--are either destroyed by the change of
medium or are widely disseminated in this ocean and are
lost there. Only the bacteridium has escaped the dilution
because it has multiplied in each of the cultures.
But a drop from the last culture kills a rabbit or guinea

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