HEART AND BLOOD. 31 



Taxation it reappeared again, red and like the point of a pin; 

 so that betwixt the visible and invisible, betwixt being and not 

 being, as it were, it gave by its pulses a kind of representation 

 of the commencement of life. 1 



CHAPTER V. 



OP 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 

 foUows : 



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

 contraction throws the blood, (which it contains in ample quan- 

 tity 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 ven- 

 tricles, 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 func- 

 tion, and all things else, is an artery; the left ventricle send- 

 ing 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 auri- 

 cles, 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 move- 

 ments 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 simultane- 

 ously ; or in that mechanical contrivance which is adapted to 

 firearms, where the trigger being touched, down comes the flint, 

 strikes against the steel, elicits a spark, which falling among the 



1 [At the period Harvey indicates, a rudimentary auricle and ventricle exist, but 

 are so transparent that unless with certain precautions their parietes cannot be seen. 

 The filling and emptying of them, therefore, give the appearance of a speck of blood 

 alternately appearing and disappearing. ED.] 



