428 PAPILLA OF THE TON&UE. 



The idea of taste may arise irrespectively of the presence of any actual 

 substance. A sharp blow will produce it, as also the passage 

 ent on acci- of a feeble voltaic current. It was, indeed, in this way that 

 dental agents. ^ fa s j. O "b serva ti n in galvanic electricity was made. A 

 narrow jet of air directed upon the tongue causes a taste resembling that 

 of saltpetre. If the tongue be dry and parched, its power of discrim- 

 inating tastes is greatly enfeebled, and the same thing takes place if its 

 temperature is very much changed, either by elevation or depression, 

 as by keeping it for a short time in contact with hot or very cold water. 



The action of the tongue, as the organ of taste, depends upon the pa- 

 e pillae which are on its surface. These structures give to the 



Structure of r ^ ... & 



the papiii* of upper portion of the tongue its rough appearance. They are 

 of three kinds : 1st. The conical papillae, which are the most 

 numerous ; 2d. The circumvallate papillae, which are situate near the 

 base of the organ, and which are from -^ to -^ of an inch in diameter, 

 with a crater-like depression, round the edge of which is a groove, and 

 again a circular elevation; 3d. The fungiform papillae, which are chiefly 

 on the sides and tip, their shape being conical, the narrow end of the cone 

 being downward. The epithelium of the tongue is less dense over the 

 fungiform papillae, and hence their projecting appearance : it is more dense 

 over the conical papillae, and projects from them in processes which pre- 

 sent an aspect like that of hairs. Some of them contain hair-tubes. 

 Besides these, the surface of the tongue presents a papillary structure 

 resembling that of the skin secondary papillae, as they are termed. It 

 is supposed that the conical papillae are chiefly organs of prehension ; the 

 others are organs of taste, but that function is participated in by other 

 portions of the surface of the mouth, as, for example, the soft palate, its 

 arches, and the tonsils. 



Fig. 207 represents the surface of the tongue and the adjacent parts : 

 #, a, lingual papillae ; , b, circumvallate papil- 

 lae, disposed along two converging lines form- 

 ing the lingual V; c, foramen ccecum ; d, d^ 

 fungiform papillae ; e, 6, filiform papillae ; /", 

 fraenum epiglottidis ; g, epiglottis ; 7z, anterior 

 pillar of velum ; i, stylo-glossus ; Z, isthmus 

 of the fauces ; ra, uvula ; n, velum pendulum 

 palati ; 0, hard palate ; p, raphe ; , , orifices 

 of the excretory ducts of the palatine glands ; 

 f, palatine glands, the mucous membrane be- 

 ing removed ; , palatine glandules ; , mu- 

 cous membrane covering the same glands ; u, 

 palatine tubercle ; i?, v, section of the lower 



The tongue. J a W. 



