href="@public@vhost@g@gutenberg@html@files@47448@[email protected]#Footnote_15_15" class="fnanchor pginternal" tag="{http://www.w3.org/1999/xhtml}a">[15] Harvey returns to this subject; and again, twenty-one years later, in his first exercise to Riolanus, as follows:—

"Our learned author mentions a certain tract of his on the Circulation of the Blood: I wish I could obtain a sight of it; perhaps I might retract. But had the learned writer been so disposed, I do not see but that, having admitted the circular motion of the blood (and in the veins, as he says in the eighth chapter of the third book,[16] the blood incessantly and naturally ascends, or flows back, to the heart, as in all the arteries it descends or departs from the heart), all the difficulties which were formerly felt in connection with the distribution of chyle and the blood by the same channels are brought to an equally satisfactory solution; for all the mooted difficulties vanish when we cease to suppose two contrary motions at once in the same vessels, and admit but one and the same continuous motion in the mesenteric vessels from the intestines to the liver."[17]

From this passage we see, in passing, that Harvey at the age of seventy made little account of Caspar Aselli's discovery of the lacteals, published twenty-two years before in 1627,[18] the year before the announcement of the discovery of the circulation. Harvey's mind was focused on the blood, its motion and its meaning; this was to him the subject of prime importance. The ancient doctrine of the feeding of the tissues provided an insufficient reason for the existence of what his observations and his experiments revealed to him.

CHAPTER III

RESPIRATION AND THE CIRCULATION

So the feeding of the tissues could not sufficiently account, to Harvey's mind, for the swiftness of the circulation. What could? It is easy for us to recite the multitudinous modern duties of the blood as a bearer of cells and of chemicals from point to point and as a protector against poisoning; above all it is easy to exclaim "respiration";—to read the most striking part of the riddle by knowing the answer which was wrung laboriously from Nature after Harvey had died. It is easy for us to see that speedy death from loss of the circulating blood is practically the same as death from ligature of the arteries of the brain, or from drowning, or strangulation, or a broken neck. But this was veiled from him, and what best accounts for the volume and swiftness of the Harveian circulation was, in Harvey's day, a stumbling block to its acceptance; for no adequate reason was apparent why the whole mass of the blood should traverse the lungs, or why, if the veins receive their blood from the arteries, the venous blood should differ in color from the arterial.

Let us remember that throughout Harvey's life air was still an elementary body in the eyes of many and, for all, blood was a quite mysterious, ruddy, hot, vital liquid. Only weak magnifying glasses were available for him, and the powerful lenses of Malpighi and van Leeuwenhoek had not yet revealed to the world either capillary or blood-corpuscle. Moreover, the gossiping John Aubrey, the man who had been advised about his youthful studies by Harvey, wrote of him some years after his death, that "he did not care for Chymistrey, and was wont to speake against them [the chemists] with an undervalue."[19] Where would physiology be to-day, had not histology and chemistry long stood in the forefront beside her?

In a passage of the treatise of 1628 Harvey speaks of respiration, as follows:—

"And now it has come to this, that it would seem better worth while and more straightforward for those who seek the path by which in man the blood passes through the vena cava into the left ventricle and the venous artery,[20] to be willing to search for the truth by dissecting animals, in order to look for the reason why in the larger and more perfect animals, when full grown, nature chooses to make the blood percolate through the parenchyma of the lungs rather than take wide open paths as in all other animals (it being understood that no other path and transit can be thought out):—whether it is because the larger and more perfect animals are hotter and when they are full grown their heat is more ignited, so to speak, and prone to be smothered, that there is this permeation and transfer through the lungs in order that the heat may be tempered by the inspired air and guarded from boiling up and smothering—or for some other similar reason. But to determine these matters and explain them completely were to enter on a speculation as to the purpose for which the lungs are made. About these and their use and motion, and the whole subject of ventilation and the need and use of air, and other matters of this sort, and about the various different organs created in animals by reason thereof, although I have made a vast number of observations, I shall not speak till I can more conveniently set them forth in a treatise apart, lest by wandering at this point too far from my subject, which is the motion and use of the heart, I should seem to deal with something else and leave my position, to confuse and evade the question."[21]

Farther on in the same treatise Harvey says:—

"Moreover, the reason why the lungs have vessels so ample, both vein and artery, that the trunk of the venous artery exceeds in size the crural and jugular branches taken both together; and the reason why the lungs are so full of blood as we know them to be by experience and inspection (heeding Aristotle's warning,[22] and not deceived by the inspection of such lungs as we have removed from dissected animals from which all the blood had flowed out)—the reason is, that in the lungs and heart is the storehouse, the source, the treasury of the blood, the workshop of its perfection."[23]

So the great Englishman gropes for a moment or two by the light of ancient Greek doctrines and puts the question of respiration by. But this very attitude shows Harvey's thought to be in such contrast with the thought of to-day that in order to understand him we need to learn more fully his views of respiration; and we find with satisfaction that in his lecture notes of more than eleven years before he had not put this question by, for he had been called upon to lecture upon the uses of the lungs. We must seek