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CHAPTER XV. 



OF TASTE. OF THE MUCOUS MEMBRANE OF THE TONGUE, AND OF ITS 



SIMPLE AND COMPOUND PAPILLuE. NERVES OF TASTE. NERVES OF 



TOUCH IN THE TONGUE. SEAT AND PHENOMENA OF TASTE. 



THE sense of taste is subservient to the nutritive function by 

 guiding us in the discrimination of the qualities of our food, and is 

 therefore appropriately situated in the mouth, the antechamber to 

 the digestive canal. The 'food being delayed more or less in this 

 cavity, is brought, by the movements to which it is exposed, into 

 intimate and varied contact with the surface; and, its properties being 

 ascertained while it is still under voluntary controul, we are able to 

 reject it or to propel it onwards, according to the impression pro- 

 duced on the nerves of taste. 



The mucous membrane of the tongue, as the principal seat of the 

 sense, will now demand description. The muscular apparatus of 

 this organ, though increasing its powers of taste, relates chiefly to 

 its employment in the processes of mastication and deglutition, and 

 will therefore be considered at a future page. 



In the mucous membrane of the tongue we find a chorion, a 

 papillary structure, and an epidermis or epithelium; all corresponding, 

 in essential characters, with the same constituents of the skin. 



The ctiorion, or cutis, is tough, but thinner and less dense than in 

 most parts of the skin : it receives the insertion of all the intrinsic 

 muscles of the tongue, which send up their fibres to it in small separate 

 bundles, so that the surface of the tongue is exceedingly mobile, even 

 in its minute portions, and its powers as an organ of touch are thereby 

 much exalted. The termination of the muscular fibres in the fibrous 

 tissue of the chorion can be well seen in thin vertical sections. The 

 chorion contains the ramifications of the vessels and nerves from 

 which the papillary structure is supplied. Both the arteries and 

 veins form plane plexuses, open on all sides, like those of the skin, 

 and respectively connected with the vessels of the papillae above 

 them. 



The papillary structure has, in general, this peculiarity, that it is 

 not concealed under the epithelium, but stands out freely from tjie 



