Curtis Harvey's views on the use of
Circulation, etc., New York, 1916.
(32) Osler An Alabama Student and Other Biographical Essays,
Oxford, 1908, p. 295.
To summarize--until the seventeenth century there were believed to
be two closed systems in the circulation, (1) the natural, containing
venous blood, had its origin in the liver from which, as from a
fountain, the blood continually ebbed and flowed for the nourishment of
the body; (2) the vital, containing another blood and the spirits, ebbed
and flowed from the heart, distributing heat and life to all parts. Like
a bellows the lungs fanned and cooled this vital blood. Here and there
we find glimmering conceptions of a communication between these systems,
but practically all teachers believed that the only one of importance
was through small pores in the wall separating the two sides of the
heart. Observation--merely looking at and thinking about things--had
done all that was possible, and further progress had to await the
introduction of a new method, viz., experiment. Galen, it is true, had
used this means to show that the arteries of the body contained blood
and not air. The day had come when men were no longer content with
accurate description and with finely spun theories and dreams.
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