es ore furnished, impress divers motions on f!^ 

 .organ, the principal of which, called the peristaltic mo 

 tion, braises the aliment, and forces it from place to 

 rplace. 



The cesophagus receives the grosser nourishnsent, ;md 

 transmits it to ihe stomach, that prepares it: it after- 

 wards passes into the intestines, where it undergoes new 

 preparations. FPORI thence it enters into some very 

 small vessels, that convey it to those of .circulatiorj, 

 .where it assumes the name, of llond. 



Whilst the most delicate par! of the aliment is subject 

 to all these preparations, the grosser part is evacuated 

 by different ways. Sometimes the animal discharges it 

 '.as a sediment', sometimes, being transformed into a. 

 subtle liquor, it is carried to the surface of the skin by 

 an infinite number of very fine vessels, whose exterior 

 apertures are sometimes so small, that a grain of sand is 

 capable of covering several thousands of them. 



Other vessels, which, like them, communicate with 

 the surface of the skin, pump in the vapours that float 

 in. the air, and convey them into the blood. 



4. Circulation is that perpetual motion by which the 

 blood is conveyed from a point internally to the extre- 

 mities, and flows back again from the extremities to the 

 same point. The point from whence the blood springs, 

 is called the heart. It. has two motions, one of contrac- 

 tion, or. systole, by raeaus of ..which it forces out the 

 blood contained in its cavity .; -the .other of dilatation, 

 or diastole, by which it receives the blood again. 



Two kinds of vessels join to the heart: the arteries, 

 which convey the blood to the extremities: and th 

 veins, which carrj it back from the extremities io the 

 heart. 



The -arteries, have, like the heart, .their systole and 

 diastole,- aud divide and subdivide themselves, as do the 

 veins, into an infinite number of branches, which dimi- 

 nish in diameter in proportion to their distance from their 

 origin. The perpetual motion of circulation prevents 

 the corruption and extravasation, of the nutritious 'fluid, 



