e kinds of animals most apt to contract anthrax. We are thus
able to obtain, not only the attenuation of the virulence, but also its
complete suppression by a simple method of cultivation. Moreover, we see
also the possibility of preserving and cultivating the terrible microbe
in an inoffensive state. What is it that happens in these eight days at
43 degrees that suffices to take away the virulence of the bacteria? Let
us remember that the microbe of chicken cholera dies in contact with the
air, in a period somewhat protracted, it is true, but after successive
attenuations. Are we justified in thinking that it ought to be the same
in regard to the microbe of anthrax? This hypothesis is confirmed
by experiment. Before the disappearance of its virulence the anthrax
microbe passes through various degrees of attenuation, and, moreover,
as is also the case with the microbe of chicken cholera, each of these
attenuated states of virulence can be obtained by cultivation. Moreover,
since, according to one of our recent Communications, anthrax is
not recurrent, each of our attenuated anthrax microbes is, for the
better-developed microbe, a vaccine--that is to say, a virus producing a
less-malignant malady. What, therefore, is easier than to find in these
a virus that will infect with anthrax sheep, cows, and horses, without
killing them, and ultimately capable of warding off the mortal malady?
We have practised this experiment with great success upon sheep, and
when the season comes for the assembling of the flocks at Beauce we
shall try the experiment on a larger scale.

"Already M. Toussaint has announced that sheep can be saved by
preventive inoculations; but when this able observer shall have
published his results; on the subject of which we have made such
exhaustive studies, as yet unpublished, we shall be able to see the
whole difference which exists between the two methods--the uncertainty
of the one and the certainty of the other. That which we announce has,
moreover, the very great advantage of resting upon the existence of
a poison vaccine cultivable at will, and which can be increased
indefinitely in the space of a few hours without having recourse to
infected blood."(8)

This announcement was immediately challenged in a way that brought it
to the attention of the entire world. The president of an agricultural
society, realizing the enormous importance of the subject, proposed to
Pasteur that his alleged discovery s