TASTE. 



809 



The papillae circumvallatce (Fig. 200), which are the largest, are about 

 eight or ten in number and form a V-shaped row at the junction of the 

 middle and posterior two-thirds of the tongue. They consist of a central, 

 broad papilla, surrounded by an annular ring or wall of about the same 

 elevation and separated from the central papilla by a circular fissure. The 

 central papilla, as well as the surrounding wall, is covered by simple papillae. 

 Each of them receives one or more capillary loops arid nerve-filaments. 



FIG. 200. 



Vertical Section of the Circumvallate Papillae. (From Kolliker.) A, the papillae ; B, the sur- 

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

 the surface ; c, the secondary papillae. 10 /i. 



Thepapillce fungiformes (Fig. 201) are found principally on the tip and 

 sides of the tongue, although scattered sparsely over the whole of the anterior 

 two-thirds. These are so named from their fungiform shape, being expanded 

 at their free extremity and projecting on a short, thick pedicle. They are 

 covered by simple papillae, and contain plexuses of vessels and nerves. 



FIG. 201. 



Surface and Section of the Fungiform Papillae. (From Kolliker, and after Todd and Bowman.) 

 A, the surface of a fungiform papilla, partially denuded of its epithelium, &h ; a, epithelium. B, 

 section of a fungiform papilla with the bloodvessels injected ; a, artery ; v, vein ; c, capillary loops 

 of simple papillae in the neighboring structure of the tongue. 



The papillce filiformes (Fig. 202) are by far the most numerous, and are 

 found thickly distributed over the entire surface of the anterior two-thirds 

 of the tongue. They are minute, conical in shape, and generally arranged 

 in bipenniform rows, which are more or less parallel with the two rows of 

 papillae circumvallatae. Their free surface is covered with simple papillae. 

 The epithelium covering them is greatly modified and appears in the form 

 of hair-like processes. (Fig. 202.) These processes are bathed in mucus, 

 are movable, and have a general inclination pointing backward. The exist- 

 ence of these hair-like processes on the filiform papillae suggests that this 

 variety of papillae is intimately connected with the tactile sensibility of the 

 tongue, and not with gustation. In carnivora and herbivora these processes 

 are of a horny structure, and perform an active function in the attrition 

 and prehension of food. In man their special function appears, through 



