THE SENSES. 



171 



Simple papillae also occur over most other parts of the tongue not 

 occupied by the compound papilla?, and extend for some distance behind 

 the papillae circumvallatae. The mucous membrane immediately in front 

 of the epiglottis is, however, free from them. They are commonly buried 

 beneath the epithelium; hence they are often overlooked. 



(1.) Circumvallate. These papillae (Fig. 350), eight or ten in num- 

 ber, are situate in two V-shaped, lines at the base of the tongue (1, 1, 



FIG. 350. Vertical section of a circumvallate papilla 10-1. A, the papillae; B, the surrounding 

 wall; a, the epithelial covering; 6, the nerves of the papilla and wall spreading toward the surface; 

 c, the secondary papillae. (Kolliker.) 



Fig. 349). They are circular elevations from ^ T) to T ^th of an inch wide, 

 each with a central depression, and surrounded by a circular fissure, at 

 the outside of which again is a slightly elevated ring, both the central 

 elevation and the ring being formed of close set simple papillae (Fig. 350). 

 (2.) Fungiform. The fungiform papillae (3, Fig. 349) are scattered 

 chiefly over the sides and tip, and sparingly over the middle of the dor- 

 sum, of the tongue; their name is derived from their being usually nar- 



FIG. 351. Surface and section of the fungiform papillae. A, the surface of a fungiform papilla, 

 partially denuded of its epithelium; p, secondary papillae; e, epithelium. B, section of a fungiform 

 papilla with the blood-vessels injected; a, artery; v, vein; c, capillary loops of similar papillae in the 

 neighboring structure of the tongue; d, capillary loops of the secondary papillae; e, epithelium. 

 (From Kolhker, after Todd and Bowman.) 



rower at their base than at their summit. They also consist of groups of 

 simple papillae (A, Fig. 351), each of which contains in its interior a loop 

 of capillary blood-vessels (B), and a nerve-fibre. 



(3.) Conical or Filiform. These, which are the most abundant 

 papillae, are scattered over the whole surface of the tongue, but especially 

 over the middle of the dorsum (Fig. 349). They vary in shape some- 

 what, but for the most part are conical or filiform, and covered by a thick 



