re.

By this time, to be sure, as everybody knows, Lister's new methods had
made their way everywhere, revolutionizing the practice of surgery and
practically banishing from the earth maladies that hitherto had been the
terror of the surgeon and the opprobrium of his art. And these bedside
studies, conducted in the end by thousands of men who had no knowledge
of microscopy, had a large share in establishing the general belief in
the causal relation that micro-organisms bear to disease, which by about
the year 1880 had taken possession of the medical world. But they did
more; they brought into equal prominence the idea that, the cause of
a diseased condition being known, it maybe possible as never before to
grapple with and eradicate that condition.

PREVENTIVE INOCULATION

The controversy over spontaneous generation, which, thanks to Pasteur
and Tyndall, had just been brought to a termination, made it clear that
no bacterium need be feared where an antecedent bacterium had not
found lodgment; Listerism in surgery had now shown how much might be
accomplished towards preventing the access of germs to abraded surfaces
of the body and destroying those that already had found lodgment there.
As yet, however, there was no inkling of a way in which a corresponding
onslaught might be made upon those other germs which find their way into
the animal organism by way of the mouth and the nostrils, and which, as
was now clear, are the cause of those contagious diseases which, first
and last, claim so large a proportion of mankind for their victims.
How such means might be found now became the anxious thought of every
imaginative physician, of every working microbiologist.

As it happened, the world was not kept long in suspense. Almost before
the proposition had taken shape in the minds of the other leaders,
Pasteur had found a solution. Guided by the empirical success of Jenner,
he, like many others, had long practised inoculation experiments, and on
February 9, 1880, he announced to the French Academy of Sciences that he
had found a method of so reducing the virulence of a disease germ that
when introduced into the system of a susceptible animal it produced only
a mild form of the disease, which, however, sufficed to protect against
the usual virulent form exactly as vaccinia protects against small-pox.
The particular disease experimented with was that infectious malady of
poultry known familiarly as "chicken cholera." In Octo