704 THE SENSE OF TASTE. 



papillae forms a thinner layer than elsewhere, so that these 

 papillse stand out more prominently than the rest. The 

 epithelium covering the filiform papillse has been shown 

 by Todd and Bowman, to have a singular arrangement ; 

 being extremely dense and thick, and, as before men- 

 tioned, projecting from their sides and summits in the 

 form of long, stiff, hair-like processes. Many of these 

 processes bear a close resemblance to hairs, and some 

 actually contain minute hair- tubes. Blood-vessels and 

 nerves are supplied freely to the papillae. The nerves in the 

 fungiform and circumvallate papillse form a kind of plexus,- 

 spreading out brush-wise (fig. 196), but the exact mode of 

 termination of the nerve-filaments is not certainly known. 



Such, in outline, is the structure of the sensitive surface 

 of the tongue. But the tongue is not the only seat of the 

 sense of taste ; for the results of experiments as well as 

 ordinary experience shows that the soft palate and its 

 arches, the uvula, tonsils, and probably the upper part of 

 the pharynx, are endowed with taste. These parts, together 

 with the base and posterior parts of the tongue, are sup- 

 plied with branches of the glosso-pharyngeal nerve, and 

 evidence has been already adduced (p. 556 et seq.) that 

 the sense of taste is conferred upon them by this nerve. 



In most, though not in all persons, the anterior part of 

 the tongue, especially the edges and tip, are supplied with 

 taste. The middle of the dorsum is only feebly endowed 

 with this sense, probably because of the density and thick- 

 ness of the epithelium covering the filiform papillae of this 

 part of the tongue, which will prevent the sapid substances 

 from penetrating to their sensitive parts. The gustatory 

 property of the anterior part of the tongue is due, as 

 already said, (p. 548), to the lingual branches of the fifth 

 nerve. 



Besides the sense of taste, the tongue, by means also of 

 its papillae, is endued, especially at its sides and tip, with 

 a very delicate and accurate sense of touch, which renders 



