ago, at which time the British introduced the Pasteur laboratories. The
clothing protects the body and it holds back the saliva and can be looked
upon as a means of filtering the saliva of the rabid animal, most of the
saliva is held back as the teeth pierce the clothing, so that upon
entering the flesh the teeth are practically dry, and only a portion of
the virus is introduced. Upon entering the wound this small amount of
virus is further diluted by the tissue juices to the non-infectious point.
We know from actual experimental work in the laboratory that the higher
dilution will not kill."

If a portion of the brain of an animal dead from street virus is taken and
made up in a dilution of one to five hundred, and this is injected, we
find that it does not produce death. But a dilution of one to three
hundred will invariably kill. This is practically what very often happens
when one is bitten through the clothing. The saliva may be filtered and
held back so that a small amount is introduced; perhaps a dilution of one
to five hundred of the virus may get into the wound, but this is usually
not enough to cause the disease. There is no possible way of estimating
the amount of the inoculation. In such cases one's chances of never
contracting the disease are only decreased; that is all we can say.

The treating of individuals, bitten by rabid animals, in the Pasteur
Institutes, is simply the practical application of results obtained by
Pasteur from his original work on rabies virus. Pasteur was a French
chemist living in Paris, and he began his search for the cause and cure of
rabies in 1880. He hoped to find a sure method of preventing the
development of the dread disease, even if he could not find a cure for it
after it had developed. While he was pursuing this research Pasteur had
access to the cases of rabies in the Paris hospitals, and these numbered
sixty each year. He had practically an unlimited supply, for France could
furnish him with twenty-five hundred more mad dogs, and a large number of
other animals each year.

[INFECTIOUS DISEASES 245]

Pasteur devoted the remainder of his life to the study of this subject. He
collected some saliva from the mouth of a child, on December 11, 1880, who
had died at the Hospital Trousseau four hours before. This saliva he
diluted with distilled water, and this mixture he injected into rabbits,
and they all died, and the saliva taken from these rabbits when injected
into oth