HISTORY OF PHYSIOLOGY. 17 



tioned, but there was laid additional emphasis on the 

 further idea that respiration was intended to cool or 

 refrigerate the blood, and the increased breathing, follow- 

 ing heavy exercise and the consequent rise in bodily tem- 

 perature, seemed in this view amply explained. 



Modern Physiology. 



HARVEY. 



The real Renaissance of physiology dates from the cel- 

 ebrated name of William Harvey, a lecturer in anatomy in 

 the College of Physicians in L,ondon. To him we are 

 indebted for the discovery of the circulation of the blood, 

 as we now understand it. With this discovery a myriad of 

 older conceptions were forever swept away, and the founda- 

 tion laid for a real scientific study of physiological phe- 

 nomena. Harvey was convinced that the older views con- 

 cerning the heart were wrong. He was an indefatigable 

 experimenter, and was sure from his observations on the 

 living heart that it was nothing more than a pump. He 

 showed that the veins carried blood to the heart, for when 

 he tied the veins the portion next the heart became empty 

 and soon the heart itself was empty, while the vein beyond 

 the ligature was distended with accumulating blood. As 

 soon as he removed the ligature from the veins the dis- 

 tended portions emptied themselves, the veins became filled 

 near the heart, and the heart itself was distended. If, on 

 the other hand, he ligatured an artery the portion next to 

 the heart became largely swollen, the blood was gorged in 

 the distended heart, while the artery away from the ligature 

 gradually emptied itself. Now, when the ligature was re- 

 moved the heart emptied the blood into the relieved artery 

 at once. Nothing could be clearer. Harvey explained the 

 function of auricles and fairly accurately described the phe- 

 nomena of the heart's beat. 



This remarkable discovery was published in the year 

 1628, which date may be considered the beginning of Mod- 

 ern physiology, and the close of its "Middle Ages." The 



