4 



THE BLOOD 



the vessels, dividing again and again, come at 

 last to be so small that they can close their 

 ultimate pores, and keep the blood controlled with- 

 in them ; yea, though the pores of the vein and 

 of the artery lie side by side, yet the blood 

 remains within its proper bounds, nowhere passing 

 into the vessels of the breath of life. But when 

 the blood is driven with violence from the veins 

 into the arteries, forthwith there is disease ; and 

 the blood is poured the wrong way into the 

 arteries, and there withstands and dashes itself 

 against the breath of life coming from the heart, 

 and turns the course of it — and this forsooth is 

 fever." 



For many centuries after Galen, men were 

 content to worship his name and his doctrines, 

 and forsook his method. They did not follow 

 the way of experiment, and invented theories 

 that were no help either in science or in practice. 

 Here, in Galen's observation of living arteries, 

 was a great opportunity for physiology ; but the 

 example that he set to those who came after him 

 was forgotten by them, and, from the time of 

 Galen to the time of the Renaissance, physiology 

 remained almost where he had left it. Of the 

 men of the Renaissance, Servetus, Caesalpinus, 

 Ruinius, and others, Harvey's near predecessors, 

 this much only need be said here, that they did 

 not discover the circulation of the blood ; and 

 that the claim made a few years ago to this 

 discovery, on behalf of Caesalpinus, by his 

 countrymen, was not successful. But it is pro- 

 bable that Realdus (15 16-1557) did understand the 



