238 DIGESTIVE SYSTEM. 



of the membrane of the mouth are reflected upon its body, form- 

 ing by their junction a sort of bridle, which is thence extended to 

 the symjihysis : to this part, which serves to restrain the organ in 

 its motions, the name offranum liiigucR has been given. 



PapillcR. — The dorsum or anterior surface of this organ has a 

 peculiarcovering, which, though it appears to be continued from 

 the buccal membrane, is a different structure altogether, and serves 

 quite a different purpose. The surface of it is roughened, pos- 

 sessing a villous texture, everywhere studded with numerous little 

 conical eminences, called papil/ce, which are supposed to be 

 formed out of the extremities of the nerves, and to be the especial 

 seat of the sense of taste. These papillae vary in size and figure, 

 and are more abundant and larger upon the base and along the 

 sides of the organ. Interspersed with them are a number of mu- 

 cous follicles, whose apertures may be seen with the naked eye, 

 through which a mucus is discharged upon the papillary surface 

 keeping it continually moist, and rendering its perception of taste 

 more acute. 



Structure. — The tongue is said to possess a covering of com- 

 mon integument; and certainly its strong compact tunic has all 

 the appearances of skin, and presents the common tests of it : the 

 external layer is laminated, is bloodless, is insensible ; the inter- 

 nal or substantial part is tough, fibrous, vascular, and sensitive, 

 in fact, is like cutis ; and the intermediate or connecting material 

 is delicate, soft, and reticular, and forms a bed for the lodge- 

 ment of the papillae. The substance of the tongue itself consists 

 of an inter-union, or rather an incorporation of its muscles, the 

 fibres of which intersect one another, and take a variety of direc- 

 tions ; but intermixed with them is a fine adipose tissue to which 

 is owing the flabby softness of the organ, and the peculiar aspect 

 it exhibits when cut into. 



Use. — Though the tongue is emphatically denominated, from 

 its essential character, the organ of taste, it is not the only part 

 that possesses this faculty ; for the palate, the pharynx, and the 

 esophagus, it is believed, participate in it. The tongue, in addi- 

 tion to possessing this faculty, disposes of the food during man- 

 ducation, and, when sufficiently masticated, collects and thrusts 

 it, portion after portion, into the pharynx : and furthermore, at 

 the time the animal is drinking, it is not only employed as an 

 instrument of suction, but also as a canal along which the fluid 

 ascends into the pharynx. 



Organization. — Every part of this organ is plentifully supplied 

 with blood. Its arteries are the lingual, branches of large size 

 from the external carotids. The bloodvessels of either side are 

 generally found free from anastomosis with one another: if cither 



