Years before, those organisms had been seen by Pollender and Davaine, but the epoch-making advance of Koch was to grow those organisms in a pure culture outside the body, and to produce the disease artificially by inoculating animals with the cultures Koch is really our medical Galileo, who, by means of a new technique,--pure cultures and isolated staining,--introduced us to a new world.

In 1878, followed his study on the "AEtiology of Wound Infections," in which he was able to demonstrate conclusively the association of micro-organisms with the disease.

Upon those two memorable researches made by a country doctor rests the modern science of bacteriology.
The next great advance was the discovery by Pasteur of the possibility of so attenuating, or weakening, the poison that an animal inoculated had a slight attack, recovered and was then protected against the disease.

More than eighty years had passed since on May 14, 1796, Jenner had vaccinated a child with cowpox and proved that a slight attack of one disease protected the body from a disease of an allied nature.

An occasion equally famous in the history of medicine was a day in 1881, when Pasteur determined that a flock of sheep vaccinated with the attenuated virus of anthrax remained well, when every one of the unvaccinated infected from the same material had died.