William Harvey and the Discovery of the Circulation of the Blood | Page 9

and it really is quite absurd, in the face of the fact, that twenty years
afterwards we find Ambrose Pare, the great French surgeon, ascribing
this discovery to him as a matter of common notoriety, to find that
attempts are made to give the credit of it to other people. So far as I
know, this discovery of the course of the blood through the lungs,
which is called the pulmonary circulation, is the one step in real

advance that was made between the time of Galen and the time of
Harvey. And I would beg you to note that the word "circulation" is
improperly employed when it is applied to the course of the blood
through the lungs. The blood from the right side of the heart, in getting
to the left side of the heart, only performs a half-circle--it does not
perform a whole circle--it does not return to the place from whence it
started; and hence the discovery of the so-called "pulmonary
circulation" has nothing whatever to do with that greater discovery
which I shall point out to you by-and-by was made by Harvey, and
which is alone really entitled to the name of the circulation of the
blood.
If anybody wants to understand what Harvey's great desert really was, I
would suggest to him that he devote himself to a course of reading,
which I cannot promise shall be very entertaining, but which, in this
respect at any rate, will be highly instructive--namely, the works of the
anatomists of the latter part of the 16th century and the beginning of the
17th century. If anybody will take the trouble to do that which I have
thought it my business to do, he will find that the doctrines respecting
the action of the heart and the motion of the blood which were taught in
every university in Europe, whether in Padua or in Paris, were
essentially those put forward by Galen, 'plus' the discovery of the
pulmonary course of the blood which had been made by Realdus
Columbus. In every chair of anatomy and physiology (which studies
were not then separated) in Europe, it was taught that the blood brought
to the liver by the portal vein, and carried out of the liver to the 'vena
cava' by the hepatic vein, is distributed from the right side of the heart,
through the other veins, to all parts of the body; that the blood of the
arteries takes a like course from the heart towards the periphery; and
that it is there, by means of the 'anastomoses', more or less mixed up
with the venous blood. It so happens, by a curious chance, that up to
the year 1625 there was at Padua, which was Harvey's own university,
a very distinguished professor, Spigelius, whose work is extant, and
who teaches exactly what I am now telling you. It is perfectly true that,
some time before, Harvey's master, Fabricius, had not only
re-discovered, but had drawn much attention to certain pouch-like
structures, which are called the valves of the veins, found in the
muscular parts of the body, all of which are directed towards the heart,

and consequently impede the flow of the blood in the opposite direction.
And you will find it stated by people who have not thought much about
the matter, that it was this discovery of the valves of the veins which
led Harvey to imagine the course of the circulation of the blood. Now it
did not lead Harvey to imagine anything of the kind. He had heard all
about it from his master, Fabricius, who made a great point of these
valves in the veins, and he had heard the theories which Fabricius
entertained upon the subject, whose impression as to the use of the
valves was simply this--that they tended to take off any excess of
pressure of the blood in passing from the heart to the extremities; for
Fabricius believed, with the rest of the world, that the blood in the
veins flowed from the heart towards the extremities. This, under the
circumstances, was as good a theory as any other, because the action of
the valves depends altogether upon the form and nature of the walls of
the structures in which they are attached; and without accurate
experiment, it was impossible to say whether the theory of Fabricius
was right or wrong. But we not only have the evidence of the facts
themselves that these could tell Harvey nothing about the circulation,
but we have his own distinct declaration as to the considerations which
led him to the true theory of the circulation of the blood, and amongst
these the valves of the veins are not mentioned.
Fig. 4.--The circulation of the blood as demonstrated by Harvey (A.D.
1628).
Now then we