than nature.

nothing, indeed, more ancient nor of higher authority It were fruitless, moreover, elaborately to discuss the consequences and the advantages or disadvantages likely to follow to physiology and other parts of medical science from the discovery of the circulation of the blood, until it has been acknowledged as an established fact. The flood of light that breaks in on me through its means, however, is such," he goes on to say, "the aid it affords in interpreting so many problems and resolving so many doubts; in detecting the causes of so many slighter and more serious diseases and suggesting means for their cure, that it will be my business in a separate treatise to be entitled 'Medical Observations,' to lay matter before the reader that shall be worthy of the gravest consideration.”

Harvey complains that his views have never been opposed on the ground of an appeal to facts. "The Circulation of the Blood," he says, "has now been before the world for many years, illustrated by proofs cognizable to the senses, and confirmed by numerous experiments; but no one has yet attempted opposition to it on the ground of ocular testimony. Empty assertions, baseless arguments, captious cavillings, and contumelious epithets' are all that have been levelled against the doctrine and its author. But even as the waves of the Sicilian sea, excited by the blast, which

1 Harvey was actually called Quack-Circulator, by some of his opponents.

dash against the rocks around Charybdis, and hiss and foam, tossed hither and thither, are they who oppose sophistical and false reasoning to the evidence of the senses."

SECTION V.

HARVEY DISCUSSES THE CAUSE OF THE HEART'S ACTION AND MOTION OF THE BLOOD.

It is only in this Second Disquisition to Riolan that Harvey redeems the promise he makes in his first work to speak of the Cause of the motion of the Heart and Blood. The systolic action of the heart we know to be the moving power in his system; but then what causes the systolic action of the heart? Harvey is less happy in his attempt at explanation here than he always shows himself in the sphere of observation and inductive reasoning. He even falls under the influence of the old physiology, from the shackles of which he generally appears so free. But it is not for long; he speedily sweeps away the hypothetical cobwebs that have threatened for a moment to entangle him.

Here, however, it is that Harvey proceeds to say that "the blood, collected in the vena cava at the base of the heart, increasing in temperature through the intrinsic heat of the organ and becoming attenuated, swells and expands like bodies in a state of fermenta

In

tion; the effect of which is, that the auricle, becoming distended, and then contracting in virtue of its pulsific power, delivers its charge to the right ventricle." the original Exercise there is not a word of the blood getting attenuated and swelling like dough in a baking trough. But the lapse is only momentary; recovering himself immediately, Harvey gainsays what he has but just said, and declares that "he does not agree with the opinions commonly entertained on the Virtues and Causes of the Motions of the Heart; he does not believe that the blood has its powers, properties, heat and motion as gifts of the heart. The cause of the diastole, he says, is not the same as that of the systole; and the diastole, which necessarily precedes the systole, is not due to the presence in the blood of anything "of a vaporous or aereal nature." Neither does he think that the act is connected with any external agency, but is owing to "an internal principle under the control of nature!"

This is vague enough, truly, and the great observer, the inductive reasoner on the ground of fact, shows that he is now groping in the dark, and leaves us to attach any meaning we please to his words. Referring to the honourable mention Descartes has made of him—and it may be that it is what Descartes has said "on the swelling of some fluids when they fall drop by drop on a hot plate" which has led him now to speak as he does--but criticizing the conclusions of the philosopher on the diastole and systole of the heart, Harvey

objects to the diastole being taken as significant of a state of activity, when it is really one of passiveness. Neither auricles nor ventricles expand like bellows by any inherent dilating power of their own; but being soft and flexible they are filled by the blood flowing into them from the veins with which they are in communication, in the same way precisely as the fingers of a glove are distended when it is blown into by the mouth-the illustration he had originally adduced. Harvey, therefore, abandons what he had said on the puffing up of the blood as the initiatory cause of the auricular and ventricular diastole.

But the problem started--the cause of the heart's action, and so of the blood's motion, is of the rarest interest, and physiologically of the last importance. It will not be put aside without further effort to find its solution. Harvey, therefore, proceeds to say: "The heart is by no means to be thought of as a kind of chauffer or kettle communicating heat to the blood contained within it. Instead of receiving heat, the blood rather communicates heat to the heart, as it does to all parts of the body; for the blood is truly the hottest element in the body; the heart itself being furnished with the coronary artery and vein to the end that it may have warmth imparted to it. The native or innate heat I therefore regard as the common instrument of every function-as prime cause of the pulse (i.e. of the heart's systole) among the number." Somewhat alarmed by the definiteness of this con

clusion, we might imagine, he immediately adds apologetically: But this I do not mean to state absolutely; I only propose it by way of thesis ;" and it is in connection with the subject now before us, that we have Harvey, by-and-by, advancing the proposition that "the heat of the blood is engendered by the influence of the air:" "The soul, the life, the power to assume independent existence is acquired by the fœtus when it begins to breathe," says Servetus: "It is as if heat were enkindled within the foetus by the influence of the air," says Harvey.'

Harvey's predecessors, then, had the innate heat as an important agent in the animal economy; but to them, even with the hint given by Servetus as to its possible source, it was not heat simply, a constituent of the blood and bodily functions, as it is to Harvey; it was a hypothetical entity apart from the organism, a vital principle, a something in rather than of the blood.

In his assumption of heat as the moving power in the animal organism, Harvey, therefore, again meets us as the Seer; for although neither he nor his age knew aught of the correlation and conservation through mutual convertibility of the imponderables or great cosmic forces, he is still prophetic of the future. Acknowledging as many now do that the Sun through its heat transformed to motion is the power that impels the Planets in their orbits and gives so many of their 1 "On Generation," p. 530 of English translation.