Ill 



THE SENSE OF TASTE 



129 



papillae, most numerous and smallest of all, cover the greater 

 part of the dorsum of the tongue, but disappear towards its 

 base. These papillae are comparable from the genetic point of 

 view with those of the skin, and produce the rough, velvety 

 appearance that characterises the dorsal surface of the tongue. 



At the base of the circumvallate or fungiform papillae there 

 are a number of serous glands which for the most part open into 

 the fossae of the papillae and are absent in the rest of the mucous 

 membrane. 



All the circumvallate papillae and most of the fungiform are 

 endowed with a specific gus- 

 tatory capacity ; in the more 

 numerous conical or filiform 

 papillae it is entirely lacking. 



The gustatory sensibility 

 of the circumvallate and 

 fuDgiform papillae is due to 

 the fact that they contain 

 within their stratified epithe- 

 lium the peripheral organs of 

 taste known as the taste-buds 

 or bulbs, discovered almost 

 simultaneously by Loven and 

 by Schwalbe (1867). As 

 shown by Figs. 52, 53 the 

 taste-buds in the fungiform 

 papillae lie in the axis of the 



papilla; in the Circumvallate FIG. 54. Section through taste-bud of papilla foliata 



t>at>illae theV are arranged of rabbit. Highly magnified. (Ranvier.) p, gus- 



ucj ai iiagou tatory pore ; s, gustatory cell ; r, sustentacular 



Serially On the lateral Surface cell ; m, leucocyte containing granules ; e, super- 



P , ^ , , ficial epithelium cells ; n, nerve-hbres. 



oi the mucous membrane and 



in the fundus of the fossae, and are usually absent in adults on 



the edges of these and on the surface of the papilla. 



Each taste-bud, examined histologically, consists of specially 

 modified epithelial cells which together constitute a pear-shaped 

 organ, 71-81 ^ in height, and about 40 //, wide, which occupies 

 nearly the whole depth of the ordinary stratified epithelium 

 (Fig. 54). They contain two kinds of cells, of which one, known 

 as supporting cells, form a compact layer at the periphery of the 

 organ : these are inserted at the base of the taste-bud by one or 

 more protoplasmic processes, and become smaller at the periphery 

 where they are arranged so that the points turn towards the 

 opening of the pore or bud. The gustatory cells contained in 

 the axis of the bud are more slender than the supporting cells, 

 their nuclei are smaller and slightly longer, and they have 

 at the peripheral end a filiform appendage, the so-called taste- 

 hair. 



VOL. IV K 



