162 ANATOMY AND PHYSIOLOGY. 



the necessary changes of digestion. The feeling of thirst, when 

 carried to an extreme, is said to be much harder to bear than that 

 of hunger, and the most dreadful picture is given of it in some 

 accounts of shipwreck, particularly in that published of the horrible 

 calamities endured by the crew of the French frigate, the Medusa, 

 on the coast of Africa. 



The changes which take place on the tongue, in consequence of 

 the state of the stomach and intestines, depend on its intimate 

 connexion with these organs, and the nervous sympathy which is 

 established between them. The state of the tongue, the loose or 

 viscid state of the throat, the secretion of the saliva, the softness or 

 huskiness of the voice, are all influenced by the state of the 

 stomach. We attend more to the effects on the tongue than to any 

 of the rest, because it is more accessible, and affords us a sort of 

 index to the state of the stomach. In health, it is clean, red, and 

 moist ; in indigestion, it is white ; in disorders of the bowels, it is 

 more or less thickly furred ; after excess in wine or spirits, it is 

 dry and chopped ; and in typhoid cases of fever, it becomes quite 

 black. 



A great many absurd experiments have been performed, with the 

 view of elucidating the nature of digestion, on the one hand, and the 

 digestibility of various kinds of aliments, on the other. The most 

 remarkable are those of Spallanzani, a celebrated physiologist of 

 Modena. At the time when he entered upon his researches, it was 

 thought that this phenomenon was only a species of trituration, and 

 that the chyme was merely the food bruised till reduced to pulp : but 

 Spallanzani showed this not to be the case. He caused birds to swal- 

 low articles of food contained in tubes, and little metallic boxes, 

 the walls of which were pierced with holes, so as to preserve these 

 substances from all friction, but not to withdraw them from the 

 action of the liquids contained in the stomach, and he found that 

 digestion took place as under ordinary circumstances. He, there- 

 fore, justly concluded, that the gastric juice must be the principal 

 cause of the chymification of food, and to be more completely 

 assured, he had recourse to very ingenious experiments. He made 

 crows and other birds swallow little sponges attached to a thread, 

 by means of which he withdrew these bodies from the stomach after 

 they had remained there for some minutes, and had imbibed the 

 liquids contained in this cavity. Thus he procured a considerable 

 quantity of the gastric juice, which he placed in small vessels with 

 the food suitably divided : he took care at the same time to raise 



