Motion of the Heart and Blood 29 



In the same way, finally, when we see the blood in 

 arteriotomy projected now to a greater, now to a less 

 distance, and that the greater jet corresponds to the 

 diastole of the artery and to the time when the heart 

 contracts and strikes the ribs, and is in its state of 

 systole, we understand that the blood is expelled by 

 the same movement. 



From these facts it is manifest, in opposition to 

 commonly received opinions, that the diastole of the 

 arteries corresponds with the time of the heart's systole ; 

 and that the arteries are filled and distended by the 

 blood forced into them by the contraction of the 

 ventricles ; the arteries, therefore, are distended, be- 

 cause they are filled like sacs or bladders, and are not 

 filled because they expand like bellows. It is in virtue 

 of one and the same cause, therefore, that all the 

 arteries of the body pulsate, viz. the contraction of the 

 left ventricle ; in the same way as the pulmonary artery 

 pulsates by the contraction of the right ventricle. 



Finally, that the pulses of the arteries are due to 

 the impulses of the blood from the left ventricle, 

 may be illustrated by blowing into a glove, when the 

 whole of the fingers will be found to become distended 

 at one and the same time, and in their tension to 

 bear some resemblance to the pulse. For in the 

 ratio of the tension is the pulse of the heart, fuller, 

 stronger, more frequent as that acts more vigorously, 

 still preserving the rhythm and volume and order of 

 the heart's contractions. Nor is it to be expected that 

 because of the motion of the blood, the time at which 

 the contraction of the heart takes place, and that at 

 which the pulse in an artery (especially a distant one) 

 is felt, shall be otherwise than simultaneous : it is here 

 the same as in blowing up a glove or bladder ; for in a 

 plenum (as in a drum, a long piece of timber, c.) the 

 stroke and the motion occur at both extremities at the 

 same time. Aristotle, 1 too, has said, " the blood of all 



1 De Animal, iii, cap. 9. 



