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lungs was a problem： probably by a continuous transudation。 In Chapters
VIII and IX he deals with the amount of blood passing through the heart
from the veins to the arteries。 Let me quote here what he says； as it is of
cardinal import：
〃But what remains to be said upon the quantity and source of the blood
which thus passes； is of a character so novel and unheard of that I not only
fear injury to myself from the envy of a few； but I tremble lest I have
mankind at large for my enemies； so much doth wont and custom become
a second nature。 Doctrine once sown strikes deeply its root； and respect for
antiquity influences all men。 Still the die is cast； and my trust is in my love
of truth； and the candour of cultivated minds。〃＇28＇ Then he goes on to say：
＇28＇ William Harvey： Exercitatio Anatomica de Motu Cordis et
Sanguinis in Animalibus； Francofurti； 1628； G。 Moreton's facsimile reprint
and translation； Canterbury； 1894； p。 48。
I began to think whether there might not be A MOVEMENT； AS IT
WERE； IN A CIRCLE。 Now this I afterwards found to be true； and I
finally saw that the blood； forced by the action of the left ventricle into the
arteries； was distributed to the body at large； and its several parts； in the
same manner as it is sent through the lungs； impelled by the right ventricle
into the pulmonary artery； and that it then passed through the veins and
along the vena cava； and so round to the left ventricle in the manner
already indicated。〃＇29＇
＇29＇ Ibid。 p。 49。
The experiments dealing with the transmission of blood in the veins
are very accurate； and he uses the old experiment that Fabricius had
employed to show the valves； to demonstrate that the blood in the veins
flows towards the heart。 For the first time a proper explanation of the
action of the valves is given。 Harvey had no appreciation of how the
arteries and veins communicated with each other。 Galen； you may
remember； recognized that there were anastomoses； but Harvey preferred
the idea of filtration。
The 〃De Motu Cordis〃 constitutes a unique piece of work in the
history of medicine。 Nothing of the same type had appeared before。 It is a
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THE EVOLUTION OF MODERN MEDICINE
thoroughly sensible； scientific study of a definite problem； the solution of
which was arrived at through the combination of accurate observation and
ingenious experiment。 Much misunderstanding has arisen in connection
with Harvey's discovery of the circulation of the blood。 He did not
discover that the blood moved；that was known to Aristotle and to Galen；
from both of whom I have given quotations which indicate clearly that
they knew of its movement；but at the time of Harvey not a single
anatomist had escaped from the domination of Galen's views。 Both
Servetus and Colombo knew of the pulmonary circulation； which was
described by the former in very accurate terms。 Cesalpinus； a great name
in anatomy and botany； for whom is claimed the discovery of the
circulation； only expressed the accepted doctrines in the following oft…
quoted phrase：
〃We will now consider how the attraction of aliment and the process of
nutrition takes place in plants； for in animals we see the aliment brought
through the veins to the heart； as to a laboratory of innate heat； and； after
receiving there its final perfection； distributed through the arteries to the
body at large； by the agency of the spirits produced from this same aliment
in the heart。〃＇30＇ There is nothing in this but Galen's view； and Cesalpinus
believed； as did all his contemporaries； that the blood was distributed
through the body by the vena cava and its branches for the nourishment of
all its parts。＇*＇ To those who have any doubts as to Harvey's position in
this matter I would recommend the reading of the 〃De Motu Cordis〃 itself；
then the various passages relating to the circulation from Aristotle to
Vesalius。 Many of these can be found in the admirable works of Dalton；
Flourens； Richet and Curtis。＇31＇ In my Harveian Oration for 1906＇32＇ I
have dealt specially with the reception of the new views； and have shown
how long it was before the reverence for Galen allowed of their
acceptance。 The University of Paris opposed the circulation of the blood
for more than half a century after the appearance of the 〃De Motu Cordis。〃
＇30＇ De Plantis； Lib I； cap。 2。
＇*＇ Cesalpinus has also a definite statement of the circlewise process。
Ed。
＇31＇ J。 C。 Dalton Doctrines of the Circulation； Philadelphia； 1884；
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THE EVOLUTION OF MODERN MEDICINE
Flourens Histoire de la decouverte de la circulation du sang； 2d ed。； Paris；
1857； Charles Richet Harvey； la circulation du sang； Paris； 1879； John G。
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 summarizeuntil 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。 Observationmerely looking at
and thinking about thingshad 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。
It was reserved for the immortal Harvey to put into practice the
experimental method by which he de