[19] Cuv. Leçons sur l’Hist. des Sc. Nat. p. 25.
I shall now proceed to the history of the discovery of another and less obvious function, the circulation of the blood, which belongs to modern times.
CHAPTER II.
Discovery of the Circulation of the Blood.
Sect. 1.—Prelude to the Discovery.
THE blood-vessels, the veins and arteries, are as evident and peculiar in their appearance as the muscles; but their function is by no means so obvious. Hippocrates[20] did not discriminate Veins and Arteries; both are called by the same name (φλέβες) and the word from which artery comes (ἀρτηρίη) means, in his works, the windpipe. Aristotle, scanty as was his knowledge of the vessels of the body, has yet the merit of having traced the origin of all the veins to the heart. He expressly contradicts those of his predecessors who had derived the veins from the head;[21] and refers to dissection for the proof. If the book On the Breath be genuine (which is doubted), Aristotle was aware of the distinction between veins and arteries. “Every artery,” [445] it is there asserted, “is accompanied by a vein; the former are filled only with breath or air.”[22] But whether or no this passage be Aristotle’s, he held opinions equally erroneous; as, that the windpipe conveys air into the heart.[23] Galen[24] was far from having views respecting the blood-vessels, as sound as those which he entertained concerning the muscles. He held the liver to be the origin of the veins, and the heart of the arteries. He was, however, acquainted with their junctions, or anastomoses. But we find no material advance in the knowledge of this subject, till we overleap the blank of the middle ages, and reach the dawn of modern science.
[20] Sprengel, i. 383.
[21] Hist. Animal. iii. 3.
[22] De Spiritu, v. 1078.