William Harvey and the Discovery of the Circulation of the Blood | Page 8

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 this--that 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 heart--what we call the 'systole' or
contraction of the heart, and the 'diastole' or dilatation--Galen 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
master--finding that all their lives were occupied in attempting to
ascertain for themselves that which was familiar to him--I 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 example--namely, 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';