396 PAPILLA OF TONGUE : NATURE OF SENSE OF TASTE. 



cleans of all its flesh the bone he licks, and that the Lion, by 

 a single stroke of his tongue, can take off" the skin from any 

 part of the Human body. The tongue itself is made-up of 

 muscular substance, which accomplishes the varied move- 

 ments that are required in the acts of mastication and in the 

 production of articulate sounds. It is supplied with nerves 

 from the third division of the fifth pair, from the glosso- 

 pharyngeal, and from the hypoglossal ( 459). The last is 

 the motor nerve of the tongue ; the first is the one chiefly 

 concerned in the conveyance of sensory impressions from the 

 front and sides of the tongue ; and the other (the glosso- 

 pharyngeal) seems, to have for its office to convey those im- 

 pressions from the back of .the tongue which excite the muscles 

 of swallowing to action ( 470), as well as those which produce 

 the sensation of nausea and excite the act of vomiting. The 

 gustative papillae, which have a very thin epithelial covering, 

 are for the most part supplied from the fifth pair ; and the 

 branch of this proceeding to the tongue is known as the 

 lingual nerve. When they are called into action by the con- 

 tact of substances having a pleasant savour, they not unfre- 

 quently become very turgid, and rise-up from the surface of 

 the mucous membrane ; in this manner is produced the rough- 

 ness that is felt on the surface of any portion of the tongue or 

 inside of the cheek, against which a piece of barley-sugar or 

 other similar substance has lain for some little time. 



501. A considerable part of the impression produced by 

 many substances, is received through the sense of Smell rather 

 than by that of Taste. Of 4his any one may convince him- 

 self by closing the nostrils and breathing through the mouth 

 only, whilst holding in the mouth, or even rubbing between 

 the tongue and the palate, some aromatic substance ; its taste 

 is then scarcely recognised, although it is immediately per- 

 ceived when the nasal passages are re-opened, and its effluvia 

 are drawn into them. There are many substances, however, 

 whose taste, though not in the least dependent upon the 

 action of the nose, is nevertheless of a powerful character ; 

 such are sugar, salt, quinine, and vinegar. Others, again, 

 by irritating the mucous membrane, produce a sense of pun- 

 gency allied to that which the same substances (strong acids, 

 for instance, pepper, or mustard) will produce when applied 

 to the skin for a sufficient length of time. Such sensations, 



