SENSE OF TASTE. 



401 



Fig. 167. 



b. The Compound papillcr are visible to the naked eye ; and have been classified, accord- 

 ing to their shape, into the circumvallate, the fungiform, and the filiform. The Circumvnl- 

 late or calyciform papillae are eight or ten in number, and are situated in a V-shaped line 

 at the base of the tongue. Each consists of a central flattened circular projection of the 

 mucous membrane, surrounded by a tumid ring of about 

 the same elevation, from which it is separated by a narrow 

 circular fissure. The surface of both centre and border 

 is smooth, and invested by scaly epithelium, which con- 

 ceals a multitude of simple papilla?. The Fungiforrn pa- 

 pilke are scattered singly over the tongue, chiefly upon its 

 sides and tip. They project considerably from the surface, 

 and are usually narrower at the base than at their summit. 

 They contain a complex capillary plexus, the terminal 

 loops of which enter the numerous simple papillae that 

 clothe the surface of the fungiform body. They contain 

 nerve-tubes, in which a looped arrangement can be traced ; 

 and the epithelium which covers them is so thin, as to allow 

 the red colour of the blood to be seen through it. In this 

 manner they are readily distinguished from the filiform pa- 



Capillary net- work of fungiform 

 papilla of the tongue. 



pilla?, among which they lie. The Filiform papilte, like the preceding, contain a plexus of 



ig. 168. 



v 



A. Fungiform papilla, showing the secondary papillae on its surface, and at a its epithelium covering 

 them over. Magnified 35 diameters. 



B. Another, with the capillary loops of its simple papillae injected, a. Artery, v. Vein. The groove 

 around the base of some of the fungiform papillae is here represented, as well as the capillary loops, c, c, 

 of some neighbouring simple papillae. Magnified 18 diameters.] 



capillaries, and a bundle of nerve-fibres, both terminating in loops, which enter the simple 

 papillas that clothe the surface of the compound body; but instead of being covered with 

 a thin scaly epithelium, they are furnished with bundles of long pointed processes, some of 

 which approach hairs in their stiffness and structure. These are immersed in the mucus of 

 the mouth, and may be moved in any direction, though they are generally inclined back- 

 wards. 



[Fig. 169. 



Various forms of the conical compound papillae deprived of their epithelium: a, b, and especially c, 

 are the best marked, and were provided with the stiffest and longest epithelium; their simple papillae 

 are more acuminated, d, approaches the fungiform variety : e.f, come near the simple papillae. Mag- 

 nified 20 diameters.] 



34* 



