Page:The Harveian oration 1896.djvu/36

32 HARVEY AND GALEN before Galen, except Aristotle, maintained that the arteries contained only ‘spirit’ or air, not blood. Galen proved that they contained blood, not only by the familiar experi- ence of blood flowing from a cut artery (which the older anatomists explained by a supposed anastomosis between veins and arteries), but by placing two ligatures on an artery and dividing the vessel between them, when, of course, only blood would be found. He also inserted a fine cannula into the left ventricle of the heart during life, and showed that blood immediately flowed out without a moment’s interval in which the supposed spirit might have escaped}. This, he says, he demonstrated to many persons who were incredulous on the subject. Galen clearly states that the bright-coloured, thin, subtle, spirituous (in modern phrase arterial) blood formed in the left ventricle by mixture with ‘vital spirit’ concocted in the lungs with the help of the air, was violently carried by the arteries all over the body”. If we put vital air or oxygen for vital spirit it approximates strangely to the modern doctrine, though the anatomical errors are obvious and need not be dwelt upon. At the same time, the air returning to the lungs was supposed to carry off and send out in expiration what was, as it were, burnt up, smoky, or sooty matter. If we put, for ‘smoky, ‘carbonaceous,’ we have a near approach to a theory of respiration which was in vogue about fifty years ago *.

It seems strange to us that the ancients should have supposed spirit and not blood to be conveyed from the lungs to the heart by the pulmonary veins. But it should be remembered that after the ordinary asphyxial mode of death, when the heart is healthy, the left auricle and pul- monary veins are usually collapsed and empty, and would therefore have been supposed to contain, during life, air which had escaped. It is otherwise in the living animal, and it was Colombo‘ who first proved, by actual experi-

1 De Placitis, i. cap. 5; Kihn, v. Kahn, iii. p. 412.

pp. 182-4. * Realdus Columbus, De Re 2 Ibid., vi. cap. 8; Kuhn, v. p. Anatomica, Venetiis, 1559, p. 261. 572- Servetus had arrived at the same

3 De Usu Partium, vi. cap. 2; idea by induction.