HARVEY. 99 



not without some other admirable artifice" (non sine 

 artificio qiwdam admirabili). It was this artificium 

 admiralnle of which Harvey was unable to give a de- 

 scription. On account of the minuteness of their struc- 

 ture, the capillaries were beyond his sight, aided as it 

 was by a magnifying glass merely. He indeed demon- 

 strated physiologically the existence of some such pas- 

 sages ; but it remained for a later observer, with improved 

 appliances, to verify the fact. This was done by Malpighi 

 in 1 66 1, who saw in the lung of a frog, which was so 

 mounted in a frame as to be viewed by transmitted light, 

 the network of capillaries which connect the last rami- 

 fications of the arteries with the radicles of the veins. 



Harvey rightly denied that the arteries possessed any 

 pulsific power of their own, and maintained that their 

 pulse is owing solely to the sudden distension of their 

 walls by the blood thrown into them at each contraction 

 of the ventricles. But the remission which succeeds 

 the pulse was regarded by him as caused simply by 

 collapse of the walls of the arteries due to elastic re- 

 action. Knowing nothing of the muscular coat of the 

 arteries, he was unaware of the fact that the elastic 

 reaction of the arteries, after their distension, is aided 

 by the tonic contractility of their walls ; the two forces, 

 physical and vital, acting in concert with each other 

 the former converting the intermittent flow from the 

 heart into an even stream in the capillaries and veins ; 



