Chap. 31.] Progrefs of the Food. 



jinto the windpipe. The parts before thro wn u into 

 action are now relaxed ; the food is received by the 

 gullet, and is regularly but rapidly conveyed to the 

 ftomach. Fluids are conveyed to the ftornach in the 

 fame manner as folids. So perfect and exact is 

 the action of the gullet in propelling its contents, that 

 even air cannot elude its grafp, which is proved by 

 our having the power of fvvallowing air, by taking a 

 mouthful of it, and ufing the fame efforts wnich we 

 employ in fwallowing our food. 



After the food has reached the ftomach, it is ftill 

 further foftened, and at kn^th reduced to a pulpy 

 confidence, by means which we (hall prefently exa- 

 mine. It now paffes through the pylorus, or right, 

 orifice of the ftomach, into the duodenum, where it is 

 retained for fome time, and attenuated by the admixture 

 of the bile from the liver, and the pancreatic juice from 

 the pancreas. From the duodenum it paries into the 

 jejunum and ileum, in which it is moved backwards and 

 forwards by the mufcular contraction of their coats, 

 called their periftaltic motion. As it proceeds, its more 

 fluid parts are continually taken up by the lacteals, and 

 it confequently gradually becomes of a thicker con- 

 fidence. From the fmall inteftin^s it pafifes through 

 the valve of the colon into the large. Here it pro- 

 bably undergoes ftill further changes, and more of 

 its fluid parts are abforbed by the lacteals. It is at 

 length received by the end of the inteftinal tube, 

 called the rectum, and being qf no further nfe, is 

 difcharged from the body. 



The chyle, which is the product of, the digefted 

 aliment, after it enters the lymphatics, is conveyed to 

 the heart, and mixed with the mafs of blood. Let us 

 now examine the inftruments, which nature employs 

 n fo wonderful a procefs, as that of fitting dead mat- 



