216 HISTORICAL RETROSPECT OF THE CIRCULATION. 



acropolis of the body, prepared in its cavities the blood, which streamed through 

 the arteries as a nutrient fluid to all parts of the body, but never returned to 

 the heart. 



With Herophilus and Erasistratus (300 B.C.), the celebrated physicians of the 

 Alexandrian school, originated the erroneous view that the arteries contain air, 

 which was supplied to them by the respiration (hence the name artery). They 

 were led to adopt this view from the empty condition of the arteries after death. 

 By experiments upon animals, Galen disproved this view (131-201 A.D.) " When- 

 ever I injured an artery," he says, "blood always flowed from the wounded vessel. 

 On tying part of an artery between two ligatures, the part of the artery so 

 included is always filled with blood." 



Still, the idea of a single centrifugal movement of the blood was retained, 

 and it was assumed that the right and left sides of the heart communicated 

 directly by means of openings in the septum of the heart until Vesalius showed 

 that there are no openings in the septum. Michael Servetus (the Spanish monk, 

 burned at Geneva, at Calvin's instigation, in 1553) discovered the pulmonary 

 circulation. Cesalpinus confirmed this observation, and named it " Circulatio." 

 Fabricius ab Aquapendente (Padua, 1574) investigated the valves in the veins 

 more carefully (although they were known in the fifth century to Theodoretus, 

 Bishop in Syria), and he was acquainted with the centripetal movement of the 

 blood in the veins. Up to this time it was imagined that the veins carried blood from 

 the centre to the periphery, although Vesalius was acquainted with the centripetal 

 direction of the blood-stream in the large venous trunks. At length, William 

 Harvey, who was a pupil of Fabricius (1604) demonstrated the complete circula- 

 tion (1616-1619), and published his great discovery in 1628. [For the history of 

 the discovery of the circulation of the blood, see the works of Willis on "W. 

 Harvey," "Servetus and Calvin," those of Kirchner, and the various Harveian 

 orations.] 



According to Hippocrates, the heart is the origin of all the vessels ; he was 

 acquainted with the large vessels arising from the heart, the valves, the chordae 

 tendiniae, the auricles, the closure of the semi-lunar valves. Aristotle was the first 

 to apply the terms aorta and venae cavse; the school of Erasistratus used the 

 term carotid, and indicated the functions of the venous valves. In Cicero a dis- 

 tinction is drawn between arteries and veins. Celsus mentions that if a vein be 

 struck below the spot where a ligature has been applied to a limb, it bleeds, while 

 Aretaeus (50 A.D.) knew that arterial blood was bright and venous dark. Pliny 

 (t 79 A.D.) described the pulsating fontanelle in the child. Galen (131-203 A.D.) was 

 acquainted with the existence of a bone in the septum of the heart of large animals 

 (ox, deer, elephant). He also surmised that the veins communicated with the 

 arteries by fine tubes. The demonstration of the capillaries, however, was only 

 possible by the use of the microscope, and employing this instrument, Malpighi 

 (1661) was the first to demonstrate the capillary circulation. Leuwenhoek (1674) 

 described the capillary circulation more carefully, as it may be seen in the web of 

 the frog's foot and other transparent membranes. Blancard (1676) proved the 

 existence of capillary passages by means of injections. William Cooper (1697) 

 proved that the same condition exists in warm-blooded animals, and Ruysch made 

 similar injections. Stenson (born 1638) established the muscular nature of the 

 heart, although the Hippocratic and Alexandrian schools had already surmised the 

 fact. Cole proved that the sectional area of the blood-stream became wider towards 

 the capillaries (1681). Joh. Alfons Borelli (1608-1679) was the first to estimate the 

 amount of work done by the heart. 



