The growth of medicine from the earliest times to about 1800

by Albert H. Buck

In his further development of a physiology of the circulation of the blood Galen, who as a rule expresses his ideas with great clearness, makes statements which I find it extremely difficult to comprehend. I am therefore tempted to assume that the copyists, to whom we are indebted for handing down his actual words from age to age, are the persons upon whom should be cast the blame for the obscurity of which I complain. However this may be, it is an unquestionable fact that the ablest physiologists, were they to be confronted to-day with the duty of solving this problem of the circulation under the conditions of knowledge which existed during the third century of our era, would surely not be able to provide a more correct solution than that which is credited to Galen. The problem was attacked repeatedly by some of the brightest and best-equipped minds of the Renaissance period, but not one of these exceptionally clever men was able to offer an entirely acceptable solution. Harvey alone, as will appear farther on in this account, solved the riddle once and for all.

The “spirit”—the purest part of the blood—is lodged, according to Galen, in the left ventricle; and, inasmuch as even the venous blood, if it is to fulfil in some degree the function of a nourishing fluid, must possess a certain proportion of “spirit,” it is clear that the two ventricles should communicate the one with the other; for how otherwise—thought Galen—is it possible for a certain amount of “spirit” to commingle with the venous blood? The locality at which this communication was assumed to exist was the interventricular septum; and, as nobody was able to find anything like a foramen in this membrane, it was asserted that the communication is effected through an infinite number of pores. For over one thousand years physicians accepted this porous character of the interventricular septum as an established fact. In his commentaries on Mondino’s “Anatomy” (1521), Berengarius of Carpi timidly ventured the statement that the openings of communication are not distinctly visible, and this apparently was the first feeble expression of doubt concerning the correctness of the prevailing doctrine. Vesalius, on the other hand, boldly denied their existence altogether.

According to Galen’s teaching the liver is the source of origin of all the veins, just as the heart is the starting-point of all the arteries. It is quite remarkable, says Flourens, that physicians who performed almost daily the operation of venesection should, during a long series of years, have failed to observe that this doctrine of blood flowing through the veins from the liver to the different parts of the body, could not possibly be true, inasmuch as at each such operation the vein always became distended with blood below (i.e., on the distal side of) the ligature which they applied to the part (arm, for example) before opening the vessel. This phenomenon, of course, indicated clearly that the blood in the veins flowed toward the heart, and not from any centrally located spot or organ toward the extremities. And yet—he adds—even so bright and thoughtful a man as Vesalius does not appear to have noticed this fact. Andreas Caesalpinus (1519–1603), on the other hand, did observe and correctly interpret the phenomenon; and he made the further observation that physicians were habitually applying the ligature above the spot which they expected to bleed, regardless of the fact that in so doing they were not acting in harmony with their belief concerning the circulation of blood in the veins. Caesalpinus also states, in one part of his writings, that “the blood, carried to the heart by the veins, receives in that organ its last transformation toward perfection, and is then—in this perfected state—transported by the arteries to the remotest parts of the body.” So far as it relates to the general movement of the blood this statement is correct, but it errs, as will be shown presently, in mentioning the heart as the locality where the perfecting process takes place. In his final remarks regarding the anatomical relations which exist in the two chambers of the heart Caesalpinus makes the following statement:—

Each ventricle possesses two vessels—one through which the blood reaches that chamber, and a second one which serves to carry it out of the ventricle. The vessel through which the blood enters the right ventricle is called the vena cava, and that by which it leaves this same chamber is called the pulmonary artery. The vessel through which the blood arrives in the left ventricle is called the pulmonary vein, and that through which it leaves this left chamber of the heart is known as the aorta.

The Circulation of the Blood as Elucidated by Michael Servetus.—Michael Servetus, a native of Villanueva, Spain, who in 1553 was burned alive at the stake near the city of Geneva, Switzerland, because of his heretical teachings, is not infrequently mentioned as the individual to whom credit is due for having furnished the first description of the lesser or pulmonary circulation. There is no question whatever regarding the justice of according to him at least a part of this honor, but one should be careful to specify that Servetus is entitled only to the credit of having been the first to teach that the blood, in its journey from the right to the left side of the heart, must pass entirely through the lungs. So far, his doctrine is correct; but he also taught at the same time that the fluid which enters the aorta from the left ventricle is not blood but perfected “vital spirit” (Galen), and that it becomes genuine blood only after it has tarried for a few brief instants in the ventricular chamber and has there been subjected to some unknown influence exerted by the heart itself. This second erroneous part of Servetus’ description seems to me to diminish very materially the credit to which he is otherwise entitled; and I cannot help feeling that Dezeimeris is right when he claims that Realdus Columbus, whose more perfect account of the lesser circulation was written only a little later than that of Servetus, is perhaps better entitled to the honor in question.

It is an interesting fact that Servetus introduces his disquisition on the circulation of the blood in the very midst of a treatise which bears the title “Restitution of Christianity,”—in other words, in a treatise which would never, under ordinary circumstances, be consulted by physicians in their search for information regarding an important problem in physiology like that of the circulation of the blood. In this physiologico-theological treatise Servetus, who—as I omitted to state—was a theologian as well as a physiologist, used the following expressions:—

The soul, says Holy Writ, is in the blood; as a matter of fact, the soul is the blood. And since the soul is in the blood, one should—if one wishes to learn how the soul is formed—endeavor to learn how the blood is formed; and, in order to learn how the blood is formed, it is necessary to ascertain how it moves. (Flourens.)

I am unable to state whether it was this particular chapter, or the work taken as a whole, which appeared to the ecclesiastical authorities—first those of France and afterward those of Geneva—to warrant the author’s condemnation as a heretic. And, when we are disposed to blame severely those bigots who, in the fifteenth and sixteenth centuries, manifested such a keen desire to destroy “heretics,” let us remember, with a proper sense of shame, that we still have in our midst, in this twentieth century and in this “land of freedom,” men of high social standing who are as virulent heresy-hunters as ever were the enemies of Servetus.

Experiments of Realdus Columbus.—Matthaeus Realdus Columbus, who was born at Cremona, Northern Italy, in the early part of the sixteenth century, acted for some time as Vesalius’ prosector, and must therefore have had ample opportunities for acquiring a thorough knowledge of the experimental method of studying questions in physiology. He wrote a description of the pulmonary circulation which was more lucid and nearer to the truth than any which his predecessors had furnished. This description, which will be found in his treatise on anatomy (Venice, 1559), was based largely upon experiments that he carried out upon living dogs. As rendered into English from the French version supplied by Dezeimeris, it reads as follows:—

When the heart dilates the blood passes from the vena cava into the right ventricle; from the latter chamber it is pushed into the arterial vein (the pulmonary artery), along which channel it is carried to the lung, there to be properly thinned and mixed with air. Ultimately the blood passes on into the venous artery (= the pulmonary vein), the function of which vessel is to carry this fluid, now charged with air through the action of the lung, into the left ventricle of the heart. Then follows the contraction (systole) of this organ, as a result of which action the tricuspid valves rise up into position and form a dam that prevents the return of the blood into the vena cava and the pulmonary veins. Simultaneously with this action the valves placed at the opening which represents the commencement of the aorta (left ventricle), and those placed at the opening which corresponds to the beginning of the pulmonary artery (right ventricle), yield and thus open the way for the distribution of the blood throughout the rest of the body.