98 FATHERS OF BIOLOGY. 



those days. According to Aubrey, the author was 

 thought to be crackbrained, and lost much of his practice 

 in consequence. He himself complains that contume- 

 lious epithets were levelled at the doctrine and its 

 author. It was not until after many years had elapsed, 

 and the facts had become familiar, that men were struck 

 with the simplicity of the theory, and tried to prove that 

 the idea was not new after all, and that it was to be 

 found in Hippocrates, or in Galen, or in Servetus, or in 

 Caesalpinus anywhere, in fact, except where alone it 

 existed, namely, in the work, " De Motu Cordis et 

 Sanguinis." No one seems to have denied, while Harvey 

 lived, that he was the discoverer of the circulation of the 

 blood; indeed, Hobbes of Malmesbury, his contem- 

 porary, said of him, " He is the only man, perhaps, that 

 ever lived to see his own doctrine established in his life- 

 time." 



In one important respect Harvey's account of the 

 circulation was incomplete. He knew nothing of the 

 vessels which we now speak of as capillaries. Writing 

 to Paul Marquard Slegel, of Hamburg, in 1651, he says, 

 " When I perceived that the blood is transferred from 

 the veins into the arteries through the medium of the 

 heart, by a grand mechanism and exquisite apparatus 

 of valves, I fudged that in like manner, wherever trans- 

 udation does not take place through the pores of the 

 flesh, the blood is returned from the arteries to the veins, 



