92 WILLIAM HARVEY 



led all 



the explosion, propels the ball, and the mark is attaint 

 of which incidents, by reason of the celerity with which they 

 happen, seem to take place in the twinkling of an eye. So 

 also in deglutition: by the elevation of the root of the 

 tongue, and the compression of the mouth, the food or drink 

 is pushed into the fauces, when the larynx is closed by its 

 muscles and by the epiglottis. The pharynx is then raised 

 and opened by its muscles in the same way as a sac that 

 is to be filled is lifted up and its mouth dilated. Upon the 

 mouthful being received, it is forced downwards by the 

 transverse muscles, and then carried farther by the longi- 

 tudinal ones. Yet all these motions, though executed by 

 different and distinct organs, are performed harmoniously, 

 and in such order that they seem to constitute but a single 

 motion and act, which we call deglutition. 



Even so does it come to pass with the motions and action 

 of the heart, which constitute a kind of deglutition, a trans- 

 fusion of the blood from the veins to the arteries. And if 

 anyone, bearing these things in mind, will carefully watch 

 the motions of the heart in the body of a living animal, he 

 will perceive not only all the particulars I have mentioned, 

 viz., the heart becoming erect, and making one continuous 

 motion with its auricles; but farther, a certain obscure un- 

 dulation and lateral inclination in the direction of the axis 

 of the right ventricle, as if twisting itself slightly in per- 

 forming its work. And indeed everyone may see, when a 

 horse drinks, that the water is drawn in and transmitted to 

 the stomach at each movement of the throat, which move- 

 ment produces a sound and yields a pulse both to the ear and 

 the touch; in the same way it is with each motion of the 

 heart, when there is the delivery of a quantity of blood 

 from the veins to the arteries a pulse takes place, and can 

 be heard within the chest. 



The motion of the heart, then, is entirely of this descrip- 

 tion, and the one action of the heart is the transmission of 

 the blood and its distribution, by means of the arteries, to 

 the very extremities of the body; so that the pulse which 

 we feel in the arteries is nothing more than the impulse of 

 the blood derived from the heart. 



Whether or not the heart, besides propelling the blood, 





