Motion of the 



trigger being touched, down comes the flint, strikes 

 against the steel, elicits a spark, which falling among 

 the powder, it is ignited, upon which the flame extends, 

 enters the barrel, causes the explosion, propels the ball, 

 and the mark is attained all 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, the larynx is closed by its 

 own muscles, and the epiglottis, whilst the pharynx, 

 raised and opened by its muscles no otherwise than 

 is a sac that is to be filled, is lifted up, and its mouth 

 dilated ; upon which, the mouthful being received, it 

 is forced downwards by the transverse muscles, and 

 then carried farther by the longitudinal ones. Yet are 

 all these motions, though executed by different and 

 distinct organs, 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 deglu- 

 tition, a transfusion of the blood from the veins to the 

 arteries. And if any one, 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 be- 

 coming erect, and making one continuous motion with 

 its auricles ; but farther, a certain obscure undulation- 

 and lateral inclination in the direction of the axis of 

 the right ventricle, [the organ] twisting itself slightly 

 in performing its work. And indeed every one may 

 see, when a horse drinks, that the water is drawn in< 

 and transmitted to the stomach at each movement of 

 the throat, the motion being accompanied with a 

 sound, and yielding 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 



