[ 319, ] [Book IX, 



CHAP. XXXI. 



DIGESTION. 



SttifationJ of Hunger and7'birft. 'Progrefs of the food to the Stomach* 

 Digeftion, h&iv performed by Men and Sjuadrupeds . Bj Birds.? 

 *The Gizzard of Fowls, and its Ufes.- Birds of Prey. Reaumur's 

 Experiments on the Dige/tion of Fowls. Motion of the Stomach and 

 Gizzard. Balls of Hair found in the Stomachs of Quadrupeds. 

 Go/trie Fluid.- Stomash ttfelf partly dijfolved by its Adion after 

 Death.'. Fermentation only takes place in difeafsd Stomachs. 

 What Subftances are digejiible, and the contrary. Powers of Dt- 

 geflion in different Animals. Carni-~voroii!.Gr ani-vorous.Gra- 

 tneni*vorous. Sleeping Animals. Accommodating Power of ike 

 Stomach. 



ANIMALS are powerfully admonimed to re- 

 pair the wafte of their bodies by an averfion 

 from the fenfations of hunger and thirft, and a defire 

 of that pleafure which attends the gratification of thefe 

 appetites. Solid food, being taken into the mouth, 

 is mafticated by the teeth, and mixed with faliva and 

 mucus, which, by the preffure and acYion of the parts, 

 are very copioufly exuded. Thus foftened and lubri- 

 cated, the food is conveyed to the root of the tongue, 

 and the lower jaw being now fixed by the fhutting 

 of the mouth, we are prepared to ad with the mufcles 

 which pafs the bone of {he lower jaw to that which 

 fupports the tongue, called the os hyoides, A con- 

 vulfive adlion of thcfe mufcles fuddenly draws for- 

 wards the os hyoides, the root of the tongue, and the 

 larynx ; the pharynx is enlarged, the food is forced 

 into the gullet, and in its paffage prefles down the 

 epiglottis, fo as to prevent any thing from getting 



into 



