Section 3. 

 Taste. 



The sense of taste is largely, though not quite, dependent upon 

 the sense of smell. There are certain substances which cannot 

 be distinguished when the nose is closed, there are others which 

 can be readily distinguished by the tongue alone. This has led 

 to a classification of taste sensations of which four qualities 

 exist — viz., sweet, bitter, acid, and salt. Animals are certainly 

 capable of distinguishing all of these. It is probable that each 

 distinct taste affects a particular part of the tongue ; in man it 

 has been shown that the back part is sensitive to bitter tastes, 

 the tip to sweet and saline tastes, the sides to acid tastes, while 

 the middle portion of the tongue is insensitive to any taste. The 

 flavour of a substance is not obtained by the sense of taste alone, 

 but by the union of the senses of smell and taste. Without 

 smell taste would be nearly impossible. 



Tongue Papillae. — The papillae of the tongue are spoken of as 

 filiform, fungiform, circumvallate, and foliate. The filiform occur 

 over the upper surface of the organ, and in the ox impart to it 

 its characteristic roughness. The fungiform papillae exist prin- 

 cipally on the lateral parts of the tongue ; the vallate are found 

 far back on the dorsum, and are only two or three in number in the 

 horse, twenty or thirty in the ox. The foliate papillae are char- 

 acteristically present in the horse, forming a large projection in 

 front of the pillars of the soft palate. There are none in the ox. 

 but they are very markedly present in the rabbit. The filiform 

 are in function chiefly tactile, the fungiform, circumvallate, and 

 foliate papillae, are associated with the sense of taste, and in their 

 structure are found the special nerve organs of taste, known as 

 taste buds, bulbs, or taste goblets. These are balloon or barrel 

 shaped bodies, the walls of which are formed of elongated cells 

 resembling the staves of a barrel. This structure is open top 

 and bottom ; the nerve fibrils enter below, while at the outer 

 free end is the gustatory pore, or opening into the interior of the 

 body of the bulb by which fluid finds its way in. The interior 

 of the goblet or bulb is filled with two kinds of cell closely similar 

 to those of the olfactory organ. Of these some are of a some- 

 what cylindrical shape, and are probably sustentacular. The 

 others are rod-shaped, and have at their outer ends a hair-like 

 process which projects at the pore. It appears to be essential to 

 taste that fluid should readily find its way into the pore, and as 



567 



