CHAPTER V 



OF THE MOTION, ACTION, AND OFFICE OF THE HEART 



FROM these and other observations of the like kind, 

 I am persuaded it will be found that the motion of 

 the heart is as follows : 



First of all, the auricle contracts, and in the course 

 of its contraction throws the blood, (which it contains 

 in ample quantity as the head of the veins, the store- 

 house, and cistern of the blood,) into the ventricle, 

 which, being filled, the heart raises itself straightway, 

 makes all its fibres tense, contracts the ventricles, and 

 performs a beat, by which beat it immediately sends 

 the blood supplied to it by the auricle into the arteries ; 

 the right ventricle sending its charge into the lungs 

 by the vessel which is called vena arteriosa, but which, 

 in structure and function, and all things else, is an 

 artery; the left ventricle sending its charge into the 

 aorta, and through this by the arteries to the body 

 at large. 



These two motions, one of the ventricles, another 

 of the auricles, take place consecutively, but in such 

 a manner that there is a kind of harmony or rhythm 

 preserved between them, the two concurring in such 

 wise that but one motion is apparent, especially in the 

 warmer blooded animals, in which the movements in 

 question are rapid. Nor is this for any other reason 

 than it is in a piece of machinery, in which, though 

 one wheel gives motion to another, yet all the wheels 

 seem to move simultaneously; or in that mechanical 

 contrivance which is adapted to firearms, where the 



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