EXPERIMENTS ON ANIMALS. 
61 
to describe the bacilli which have since been proved to be the 
active agents in the production of anthrax ; and the laboratory 
experiments of Pollender, Delafond, Davaine, Chaveau, Tous- 
saint, and others, but above all of Pasteur, who had already dem¬ 
onstrated the parasitic origin of the silk-worm disease, have per¬ 
fected our knowledge of the action of the virus, and the means 
by which its energy may be so attenuated that, when inoculated 
into healthy animals, instead of destroying them, it only gives 
rise to, at most, a slight ephemeral disturbance and confers im¬ 
munity from the disease. At first these results were received 
with incredulity, but in 1881 Pasteur gave a public demonstra¬ 
tion at Melun of the truth of these statements. Fifty sheep and 
twelve cattle were placed at his disposal; half the number were 
then inoculated with the cultivated or attenuated virus, and fif¬ 
teen days later all the animals were inoculated with the unculti¬ 
vated or deadly virus. Forty-eight hours later every one of the 
unprotected animals was dead, while all of the animals which had 
received^ the cultivated virus were in perfect health. But this 
was not all. It had been claimed that the deadly virus was a 
laboratory product, and, perhaps, not the true essence of the 
disease, and it was proposed that the anthrax blood, whose deadly 
effects on man and animals were so well known, should be used 
as a test of protective inoculation. An official, commission was 
therefore appointed at Chartres to set the matter at rest, and 
twenty sheep were allowed for the experiments. Similar results 
were obtained. Those inoculated with the attenuated virus were 
not in the least affected when they received what would other¬ 
wise have been a deadly quantity of anthrax blood, while of those 
not thus protected all died but one. 
“ There was no longer any doubt as to the value of protective 
inoculation, and there was the greatest anxiety to have the flocks 
in the anthrax-haunted districts protected as soon as possible. 
Up to October, 1881, 58,900 animals had been inoculated in the 
proportion of three to five, i. e., 33,576 against 21,938, which 
were left unprotected to show the difference. Before inoculation 
the loss in all the flocks had been 2,986. During the inoculation 
and until the effects were complete, 260 died in the group of 
33,576 which was being operated on; and during the same time 
