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the branches of the veins。 But the whole of the blood was not thus
disposed of。 Part of the blood； it was supposed； went through what we
now call the pulmonary arteries （Fig。 1）； and； branching out there； gave
exit to certain 〃fuliginous〃 products； and at the same time took in
from the air a something which Galen calls the 'pneuma'。 He does not
know anything about what we call oxygen； but it is astonishing how very
easy it would be to turn his language into the equivalent of modern
chemical theory。 The old philosopher had so just a suspicion of the
real state of affairs that you could make use of his language in many
cases； if you substituted the word 〃oxygen；〃 which we now…a…days use；
for the word 'pneuma'。 Then he imagined that the blood； further
concocted or altered by contact with the 'pneuma'； passed to a certain
extent to the left side of the heart。 So that Galen believed that
there was such a thing as what is now called the pulmonary
circulation。 He believed； as much as we do； that the blood passed
through the right side of the heart； through the artery which goes to
the lungs； through the lungs themselves； and back by what we call the
pulmonary veins to the left side of the heart。 But he thought it was
only a very small portion of the blood which passes to the right side of
the heart in this way； the rest of the blood； he thought； passed
through the partition which separates the two ventricles of the heart。
He describes a number of small pits； which really exist there； as
holes； and he supposed that the greater part of the blood passed
through these holes from the right to the left ventricle （Fig 2）。
It is of great importance you should clearly understand these teachings
of Galen； because； as I said just now； they sum up all that anybody
knew until the revival of learning； and they come to thisthat the
blood having passed from the stomach and intestines through the liver；
and having entered the great veins； was by them distributed to every
part of the body； that part of the blood； thus distributed； entered the
arterial system by the 'anastomoses'； as Galen called them； in the
lungs； that a very small portion of it entered the arteries by the
'anastomoses' in the body generally； but that the greater part of it
passed through the septum of the heart； and so entered the left side
and mingled with the pneumatised blood； which had been subjected to the
air in the lungs； and was then distributed by the arteries； and
eventually mixed with the currents of blood； coming the other way；
through the veins。
Yet one other point about the views of Galen。 He thought that both the
contractions and dilatations of the heartwhat we call the 'systole'
or contraction of the heart； and the 'diastole' or dilatationGalen
thought that these were both active movements； that the heart actively
dilated； so that it had a sort of sucking power upon the fluids which
had access to it。 And again； with respect to the movements of the
pulse； which anybody can feel at the wrist and elsewhere； Galen was of
opinion that the walls of the arteries partook of that which he
supposed to be the nature of the walls of the heart； and that they had
the power of alternately actively contracting and actively dilating； so
that he is careful to say that the nature of the pulse is comparable；
not to the movement of a bag； which we fill by blowing into it； and
which we empty by drawing the air out of it； but to the action of a
bellows； which is actively dilated and actively compressed。
Fig 3。The course of the blood from the right to the left side of the
heart （Realdus Columbus； 1559）。
After Galen's time came the collapse of the Roman Empire； the extinction
of physical knowledge； and the repression of every kind of scientific
inquiry； by its powerful and consistent enemy； the Church； and that
state of things lasted until the latter part of the Middle Ages saw the
revival of learning。 That revival of learning； so far as anatomy and
physiology are concerned； is due to the renewed influence of the
philosophers of ancient Greece； and indeed； of Galen。 Arabic
commentators had translated Galen； and portions of his works had got
into the language of the learned in the Middle Ages； in that way； but；
by the study of the classical languages； the original text became
accessible to the men who were then endeavouring to learn for
themselves something about the facts of nature。 It was a century or
more before these men； finding themselves in the presence of a
masterfinding that all their lives were occupied in attempting to
ascertain for themselves that which was familiar to himI say it took
the best part of a hundred years before they could fairly see that their
business was not to follow him； but to follow his examplenamely； to
look into the facts of nature for themselves； and to carry on； in his
spirit； the work he had begun。 That was first done by Vesalius； one of
the greatest anatomists who ever lived； but his work does not specially
bear upon the question we are now concerned with。 So far as regards
the motions of the heart and the course of the blood； the first man in
the Middle Ages； and indeed the only man who did anything which was of
real importance； was one Realdus Columbus； who was professor at Padua
in the year 1559； and published a great anatomical treatise。 What
Realdus Columbus did was this； once more resorting to the method of
Galen； turning to the living animal； experimenting； he came upon new
facts； and one of these new facts was that there was not merely a
subordinate communication between the blood of the right side of the
heart and that of the left side of the heart； through the lungs； but
that there was a constant steady current of blood； setting through the
pulmonary artery on the right side； through the lungs； and back by the
pulmonary veins to the left side of the heart （Fig。3）。 Such was the
capital discovery and demonstration of Realdus Columbus。 He is the man
who discovered what is loosely called the 'pulmonary circulation'； 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…circleit
does not perform a whole circleit 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 instructivenamely； 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 Harve