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

Thomas Henry Huxley
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 may come to Harvey himself. When you read Harvey's treatise, which is one of the most remarkable scientific monographs with which I am acquainted--it occupies between 50 and 60 pages of a small quarto in Latin, and is as terse and concise as it possibly can be--when you come to look at Harvey's work, you will find that he had long struggled with the difficulties of the accepted doctrine of the circulation. He had received from Fabricius, and from all the great authorities of the day, the current view of the circulation of the blood. But he was a man with that
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