134 MICROBES, FERMENTS, AND MOULDS, 
and butchers who break and handle the bones of 
animals which have died of anthrax. 
The period of incubation is very short. An ox 
which has been at work may return to the stall 
apparently healthy. He eats as usual; then lies down 
on his side and breathes heavily, while the eyes are 
still clear. Suddenly his head drops, his body grows 
cold; at the end of an hour the eye becomes glazed ; 
the animal struggles to get up, and falls dead. In 
this case, the illness has only lasted for an hour and 
a half (Empis). 
A\ ee, 
gp ° e'= & 
> 27h 82)\7 
e& a @ °_ —@ 
Fig. 69.—Bacillus anthracis, produced in guinea-pig by inoculation: corpuscles of 
blood and bacilli. 
In order to prove that the disease is really caused 
by Bacillus anthracis, Pasteur inserted a very small 
drop of blood, taken from an animal which had 
‘recently died of anthrax, in a glass flask which con- 
tained an infusion of yeast, neutralized by potassium 
and previously sterilized. In twenty-four hours the 
liquid, which had been clear, was seen to be full of 
very light flakes, produced by masses of bacilli, readily 
