THE CIRCULATION OF THE BLOOD 449 



stood the mechanism of the heart, and comprehended that 

 its contraction was the cause of the motion of the blood ; 

 and thirdly, he was the first person who took a just view of 

 the nature of the pulse. These are the three great contribu- 

 tions which he made to the science of physiology ; and J 

 shall not err in saying I speak in the presence of distin- 

 guished physiologists, but I am perfectly certain that they 

 will endorse what I say that upon that foundation the 

 whole of our knowledge of the human body, with the excep- 

 tion of the motor apparatus and the sense organs, has been 

 gradually built up, and that upon that foundation the whole 

 rests. And not only does scientific physiology rest upon it, 

 but everything like scientific medicine also rests upon it. 

 As you know I hope it is 

 now a matter of popu- 

 lar knowledge it is the 

 foundation of all rational 

 speculation about morbid 

 processes ; it is the only 

 key to the rational interpre- 

 tation of that commonest of 

 all indications of disease, the 

 state of the pulse; so that, 

 both theoretically and practi- 

 cally, this discovery, this FIG. 5. The junction of the arteries 

 demonstration of Harvey's, $& b b y y fflffii * 



has had an effect which is 1664). 



absolutely incalculable, and 



the consequences of which will accumulate from age to 

 age until they result in a complete body of physiological 

 science, 



I regret that I am unable to pursue this subject much 

 further; but there is one point I should mention. In 

 Harvey's time, the microscope was hardly invented. It is 

 quite true that in some of his embryological researches he 

 speaks of having made use of a hand glass ; but that was the 

 most that he seems to have known anything about, or that 

 was accessible to him at that day. And so it came about, 

 that, although he examined the course of the blood in many 

 of the lower animals watched the pulsation of the heart in 

 shrimps, and animals of that kind he never could put the 

 final coping-stone on his edifice. He did not know to the day 

 of his death, although quite clear about the fact that the 

 arteries and the veins do communicate, how it is that they 

 660 



