THE CIRCULATION OF THE BLOOD 445 



motion of the blood which were taught in every university 

 In Europe, whether in Padua or in Paris, were essentially 

 those put forward by Galen, plus the discovery of the pul- 

 monary course of the blood which had been made by Realdus 

 Columbus. In every chair of anatomy and physiology 

 (which studies were not then separated) in Europe, it was 

 taught that the blood brought to the liver by the portal 

 vein, and carried out of the liver to the vena cava by the 

 hepatic vein, is distributed from the right side of the heart, 

 through the other veins, to all parts of the body ; that the 

 blood of the arteries takes a like course from the heart 

 towards the periphery ; and that it is there, by means of 

 the anastomoses, more or less mixed* up with the venous 

 blood. It so happens, by a curious chance, that up to the 

 year 1625 there was at Padua, which was Harvey's own 

 university, a very distinguished professor, Spigelius, whose 

 work is extant, and who teaches exactly what I am now 

 telling you. It is perfectly true that, some time before, 

 Harvey's master, Fabricius, had not only re-discovered, 

 but had drawn much attention to certain pouch-like 

 structures, which are called the valves of the veins, found 

 in the muscular parts of the body, all of which are directed 

 towards the heart, and consequently impede the flow of the 

 blood in the opposite direction. And you will find it stated 

 by people who have not thought much about the matter, that 

 it was this discovery of the valves of the veins which led 

 Harvey to imagine the course of the circulation of the blood. 

 Now it did not lead Harvey to imagine anything of the kind. 

 He had heard all about it from his master, Fabricius, w r ho 

 made a great point of these valves in the veins, and he had 

 heard the theories which Fabricius entertained upon the 

 subject, whose impression as to the use of the valves was 

 simply this that they tended to take off any excess of 

 pressure of the blood in passing from the heart to the 

 extremities ; for Fabricius believed, with the rest of the world, 

 that the blood in the veins flowed from the heart towards 

 the extremities. This, under the circumstances, was as 

 good a theory as any other, because the action of valves 

 depends altogether upon the form and nature of the walls 

 of the structures in which they are attached ; and, without 

 accurate experiment, it was impossible to say whether the 

 theory of Fabricius was right or wrong. But we not only 

 have the evidence of the facts themselves that these could 

 tell Harvey nothing about the circulation, but we have 



