92 
Pasteur and his Worh^ 
perishes, for when sown into a fresh medium there is no result ; 
though in the preceding days life is still present in them. When 
the cultivation is exposed to air and warmth for two, four, six, or 
eight days, and is then inoculated in animals, its activity is 
found to be modified in proportion to the duration of exposure ; 
it presents, in fact, a succession of gradually attenuated viruses, 
as in fowl-cholera, each constituting a foil for the uncultivated 
microbe. 
The announcement of a method of protection from the most 
serious animal disease in France, was made on February 28th, 
1881, to the Academy of Sciences, where it was received with 
great acclamation, and immediately afterwards the President of 
the Society of Agriculture of Melun, on behalf of the Society, 
invited Pasteur to give a public demonstration of his method of 
conferring immunity from splenic fever ; this invitation he 
accepted, and sixty sheep were placed at his disposal. It was 
arranged that ten of these were to be left untouched ; twenty-five 
were to receive an inoculation of very attenuated virus, and in 
twelve to fifteen days another inoculation of stronger cultivated 
virus. Some days afterwards these twenty-five sheep, with the 
other twenty-five which had not been protected, were to be 
inoculated with the crude mortiferous virus of anthrax. 
Ten cows were also given for experiment — six to be inocu- 
lated, four not ; the ten were afterwards, the same day as the 
fifty sheep, to be inoculated with uncultivated virus. Pasteur 
prognosticated that the twenty-five sheep which had not been 
inoculated would die, and the other twenty-five, protected ones, 
would survive ; also, that the six inoculated cows would resist 
the poison, while the four which had not been inoculated, even 
if they did not die, would at least be extremely ill. This 
prediction startled many of his colleagues at the Academy of 
Sciences, and some of them designated it a scientific impru- 
dence, which his laboratory experiments scarcely warranted. 
Pasteur, however, had perfect confidence in the result, as had 
also his friend and warm admirer, M. Bouley. 
On May the 5th, the experiment was commenced on a farm 
belonging to a veterinary surgeon, M. Rossignol, who was Secre- 
tary-General of the Melun Agricultural Society. At the desire 
of the Society, a goat was substituted for one of the twenty-five 
sheep of the first lot. Twenty-four sheep, the goat, and six cows 
were each inoculated with five drops of cultivated virus, this 
being placed beneath the skin by means of a hypodermic syringe. 
Twelve days afterwards, these animals were reinoculated with a 
stronger cultivated virus; and on May the 31st, all of the cattle 
and sheep were inoculated with very virulent uncultivated virus. 
A great number of veterinary surgeons, medical and scientific 
