85 



pharynx, and pressed into the gullet, down which it is 

 propelled, by the progressive contraction of the involuntary 

 muscular fibres of that canal, into the stomach. 



5th. — In the stomach, it is mixed with gastric juice — a fluid of an 

 acid character — which again acts chemically upon it. For 

 the better accomplishment of the process, the food is being 

 constantly rolled about, or " churned," by the action of the 

 different muscular coats of this organ. The flesh-forming 

 matters — albuminoid portions, or pvoteids — are here converted 

 into the more soluble peptones, and a portion of the nutritive 

 elements is absorbed, and carried into the portal vein, and 

 thence to the liver^; while the rest of the food is converted into 

 a soft-soap like material called chyme. 



6th. — The chyme is next passed on into the small intestine. Here 

 it is met by the bile (which the liver is constantly secreting), 

 the pancreatic juice, or intestinal saliva (formed by the 

 pancreas), and by the juices of the various small intestinal 

 glands. The pancreatic juice, which is alkaline, and somewhat 

 resembles saliva, has a powerful action on fats, converting 

 them into a such a form that they are capable of being 

 absorbed, while the bile assists in the emulsification of the 

 fats. The bile also appears to act as a natural purgative. 



7th. — The different kinds of food having now been acted upon by the 

 fluid secreted by the salivary glands and stomach, i.e., saliva 

 and gastric juice, as well as by the bite, pancreatic, and intestinal 

 fluids, the chyme is converted into a milky emulsion, called 

 chyle. While this process is going on, a portion of the new 

 material is absorbed by the vessels of the intestines, and 

 carried to the portal vein, and so to the liver. 



8th. — By the action of the muscular walls of the bowels, the cliyk is 

 forced along the intestinal track, when numerous little 

 bodies called villi, which are studded all over the lining 

 membrane, select more of tlie available nutritive material. 



