140 MICROBES, FERMENTS, AND MOULDS. 
the disease, but generally in a very mild form, and it 
is an important result of this treatment that they are 
henceforward safe from a fresh attack of the disease ; 
in a word, they are vaccinated against anthrax. 
In the cultures prepared with the view of attenu- 
ating the microbe, it is the action of the oxygen of 
the air which renders the bacteridium less virulent. 
It should be subjected to a temperature of from 42° 
to 43° in the case of Bacillus anthracis, to enable it 
to multiply, and at the same time to check the pro- 
duction of spores which might make the liquid too 
powerful. At the end of the week, the culture, which 
at first killed the whole of ten sheep, killed only four 
or five out of ten. In ten or twelve days it ceased 
to kill any; the disease was perfectly mild, as in the 
case of the human vaccinia, of which we shall speak 
presently. After the bacteridia have been attenuated, 
they can be cultivated in the lower temperature of 
from 80° to 35°, and only produce spores of the same 
attenuated strength as the filaments which form them 
(Chamberland). 
The vaccine thus obtained in Pasteur’s laboratory 
is now distributed throughout the world, and has 
already saved numerous flocks from almost certain 
destruction. Although this process has only been 
known for a few years, its results are such that the 
gain to agriculture already amounts to many thousands 
of pounds. 
Toussaint makes use of a slightly different mode 
