der the eyes of the spectators; the remaining
victims lingered but a few hours longer. Thus in a manner theatrical
enough, not to say tragic, was proclaimed the unequivocal victory of
science. Naturally enough, the unbelievers struck their colors and
surrendered without terms; the principle of protective vaccination,
with a virus experimentally prepared in the laboratory, was established
beyond the reach of controversy.

That memorable scientific battle marked the beginning of a new era
in medicine. It was a foregone conclusion that the principle thus
established would be still further generalized; that it would be
applied to human maladies; that in all probability it would grapple
successfully, sooner or later, with many infectious diseases. That
expectation has advanced rapidly towards realization. Pasteur himself
made the application to the human subject in the disease hydrophobia in
1885, since which time that hitherto most fatal of maladies has largely
lost its terrors. Thousands of persons bitten by mad dogs have been
snatched from the fatal consequences of that mishap by this method at
the Pasteur Institute in Paris, and at the similar institutes, built on
the model of this parent one, that have been established all over the
world in regions as widely separated as New York and Nha-Trang.

SERUM-THERAPY

In the production of the rabies vaccine Pasteur and his associates
developed a method of attenuation of a virus quite different from that
which had been employed in the case of the vaccines of chicken cholera
and of anthrax. The rabies virus was inoculated into the system of
guinea-pigs or rabbits and, in effect, cultivated in the systems of
these animals. The spinal cord of these infected animals was found to
be rich in the virus, which rapidly became attenuated when the cord was
dried in the air. The preventive virus, of varying strengths, was made
by maceration of these cords at varying stages of desiccation. This
cultivation of a virus within the animal organism suggested, no doubt,
by the familiar Jennerian method of securing small-pox vaccine, was at
the same time a step in the direction of a new therapeutic procedure
which was destined presently to become of all-absorbing importance--the
method, namely, of so-called serum-therapy, or the treatment of a
disease with the blood serum of an animal that has been subjected to
protective inoculation against that disease.

The possibility of such a method was