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Vaccination against Anthrax. 
VACCINATION AGAINST ANTHRAX. 
I.v his researches regarding the cause of fowl cholera, M. Pasteur dis- 
covered that when the organism of that disease is cultivated in 
liquid media freely exposed to the air it gradually loses its virulence, 
and he showed that by taking advantage of this fact one could use 
a culture of the organism to vaccinate fowls, and protect them against 
a natural attack of the disease. Following the line of inquiry thus 
suggested, M. Pasteur ascertained that when the bacilli of anthrax 
are cultivated in meat-extract at a temperature between 42° and 43 5 
Centigrade, they also gradually lose their vitality and their virulence, 
and at the end of about six weeks perish altogether. The loss of 
vitality, he discovered, was progressive, and proportionate to the 
time during which the culture had been maintained at the tempera- 
ture mentioned. This was proved by testing the effect of the cultures 
at different periods when inoculated into animals. At the outset 
the culture had all the virulence of fresh anthrax blood, but by the 
twelfth day its virulence was so diminished that when inoculated 
into sheep only half of the animals were killed ; and by the twenty- 
fourth day the culture could be inoculated into sheep without en- 
tailing the death of any, although it set up a mild febrile disturbance. 
When animals were vaccinated with the culture of the twenty- 
fourth day, and subsequently inoculated with virulent anthrax 
bacilli from the blood of an animal dead of anthrax, all, or a great 
proportion of them, died, but if the animals had been vaccinated a 
second time, with a culture of the twelfth day, they were so protected 
that they could withstand subsequent inoculation with virulent 
anthrax bacilli. As a result of this discovery M. Pasteur felt him- 
self warranted in announcing to the French Academy of Science in 
March, 1881, that he had at his command a means of protecting 
animals against anthrax, and in the following year the method which 
he proposed received its first experimental test. 
The experiment was carried out on a farm near Melun, and fifty- 
eight sheep, two goats, and ten cattle were subjected to it. Needless 
to say, it excited much interest in France, and it was executed in 
the presence of a large number of eminent agriculturists, veterinary 
surgeons, and medical men. On May 5 twenty-four sheep, one goat, 
and six cows were inoculated for the first time with a weak protective 
vaccin, and twelve days afterwards the same animals were inoculated 
a second time with a stronger vaccin. On May 31 these vaccinated 
animals, and the remainder that had not been vaccinated, namely 
twenty-four sheep, one goat, and four cattle, were inoculated with a 
virulent anthrax cultivation. On June 2 all the animals that had 
undergone protective inoculation were found in apparent health ; 
while of the others, twenty-one sheep and the goat were dead, two 
other sheep were dying, and the only remaining one was attacked 
before the day was out. The non-vaccinated cows were not dead, 
but they presented the most formidable swelling at the point of 
