134 MICKOBES, 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). 



Fie. 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 



