No solids pass through the filter. The serum passes
through and it is not infectious. The cause of the mal-
ady is, therefore, not soluble in the serum. It remains
on the surface of the filter where there are only red
corpuscles, white corpuscles and bacteridia. Choose
the cause among these three, but choose!"

Davaine was not only ambitious to demonstrate that
the bacteridium was the cause and the only cause of
the development of anthrax: he wished also to explain
by its aid the etiology of the disease, that is to say, the
different conditions governing its natural appearance
and its endemic or epidemic character. In this direc-
tion he was less successful. He had observed, as we
have just said, that putrefaction rendered the blood
incapable of transmitting anthrax. He was obliged,
therefore, to give up seeing in the blood and tissues of
an animal buried as a victim of anthrax the cause of the
revival of the disease from one year to another, in the
same region or pasture. He observed, nevertheless, that
blood rapidly dried preserved its virulence for a
long time. Now, said he, this rapid desiccation must
often occur in countries where anthrax is prevalent;
when animals are slaughtered for the sake of the skins,
pools or drops of blood remain on the ground, on the litter,
on the walls, and these dry rapidly and preserve their germs.
As for the infection of other animals, Davaine attributed
it to flies some of which by sucking, and others simply
by means of their feet, are the agents of infection among
animals in stables or the open field, and he supported
all these opinions by well carried out experiments.

There were grave objections to this etiology. If
it is the fly which disseminates the virus, it was said,
why does it sometimes respect so carefully the bound-
aries of a field or an estate? There are in Beauce and
in Auvergne dangerous fields or meadows; the adjoining

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