saw the
small "capillary" vessels connecting the veins and arteries in a piece
of dried lung. Taking his cue from this, he examined the lung of a
turtle, and was able to see in it the passage of the corpuscles through
these minute vessels, making their way along these previously unknown
channels from the arteries into the veins on their journey back to the
heart. Thus the work of Harvey, all but complete, was made absolutely
entire by the great Italian. And all this in a single generation.

LEEUWENHOEK DISCOVERS BACTERIA

The seventeenth century was not to close, however, without another
discovery in science, which, when applied to the causation of disease
almost two centuries later, revolutionized therapeutics more completely
than any one discovery. This was the discovery of microbes, by Antonius
von Leeuwenhoek (1632-1723), in 1683. Von Leeuwenhoek discovered
that "in the white matter between his teeth" there were millions of
microscopic "animals"--more, in fact, than "there were human beings in
the united Netherlands," and all "moving in the most delightful manner."
There can be no question that he saw them, for we can recognize in
his descriptions of these various forms of little "animals" the four
principal forms of microbes--the long and short rods of bacilli and
bacteria, the spheres of micrococci, and the corkscrew spirillum.

The presence of these microbes in his mouth greatly annoyed Antonius,
and he tried various methods of getting rid of them, such as using
vinegar and hot coffee. In doing this he little suspected that he was
anticipating modern antiseptic surgery by a century and three-quarters,
and to be attempting what antiseptic surgery is now able to accomplish.
For the fundamental principle of antisepsis is the use of medicines for
ridding wounds of similar microscopic organisms. Von Leenwenhoek was
only temporarily successful in his attempts, however, and took occasion
to communicate his discovery to the Royal Society of England, hoping
that they would be "interested in this novelty." Probably they were,
but not sufficiently so for any member to pursue any protracted
investigations or reach any satisfactory conclusions, and the whole
matter was practically forgotten until the middle of the nineteenth
century.

VIII. MEDICINE IN THE SIXTEENTH AND SEVENTEENTH CENTURIES

Of the half-dozen surgeons who were prominent in the sixteenth century,
Ambroise Pare (1517-1590), called the father of Fr