MASTICATION AND DIGESTION. 179 



alimentary substances into organized portions of the body. In this the 

 first process is the conversion of food into blood, and second, the for- 

 mation of tissue, &c., from the blood. In the preparation of the food 

 two substances are necessary, the hydwchloricjiicidj,nd chymosine. The 

 first is said to soften the food and cause it. to swell up, while the second 

 liquefies it. These substances are secreted in the lining membranes 

 of the stomach by a vital process. Digestion is chiefly a chemical 

 process, and may be performed out of the stomach by an artificial 

 liquor prepared by the maceration of the dried lining membrane of the 

 4th stomach of the calf in a weak solution of hydrochloric acid. By 

 the action of the gastric fluid, sugar, fatty and oily matters, starch, 

 gum, &c., are divided into minute parts ; and subsequently the pro- 

 teinaceous substances are absorbed and converted into chyle. 



The process of digestion is generally slower with vegetable than 

 with animal substances; but oils and fat are very difficult of digestion. 

 Some of the former, pass the stomach, in a crude state, while others 

 are retained ; thus it is with cathartic medicines, many fruits, seeds, 

 &c. The artificial preparations of many kinds of food also render 

 them difficult of digestion, while others are so modified by art as to be 

 easily digested. It is said that violent exercise in animals, just pre- 

 vious to death, renders their flesh more tender, and that the practice 

 of bull-bating and whipping pigs to death may have originated in a 

 knowledge of this fact. It is also believed that flesh kept for some 

 time after death, or which is in the first stages of decomposition, is 

 more easily digested than fresh meat. That of young animals is 

 thought to be more tender and soluble, but not so digestible as that 

 of older animals. The stomach disposes of solid more readily than 

 fluid food ; though, nPan exhausted condition of* the body, the latter 

 more readily restores strength. 



It is of the first importance that food should be minutely divided, as 

 the time* of digestion is much shortened by it. Thus potatoes, fruits, 

 and other vegetable substances are more easily digested by being 

 soaked, so as to be susceptible of easy mastication. Some of these are 

 much more so from their structure than others, as with mealy potatoes, 

 &c. The complete mastication of food by chewing cannot be too for-' 

 cibly impressed upon the attention of all, and especially dispeptics. 

 The complete mixture of food with the saliva is also necessary to di- 

 gestion. When this is not done, a desire is always manifested to swak 

 low drinks to moisten the food eaten ; but this cannot be so well cal- 

 culated to effect the object designed by insalivation. 



The process of cooking is designed, in addition to the gratifica- 

 tion of the taste, to destroy the organic structure of food ; hence this 

 is almost universally practiced by civilized people, with most organic 

 substances. The modes of cooking effect some remarkable changes 

 in the elements of food, as with poisonous plants, &c. But this change 







