THE SENSE OF TASTE. 



639 



1. The filiform papilla, the most numerous, cover the anterior two-thirds of 



the tongue; they are conical or filiform in shape and covered with 

 horny epithelium which is often prolonged into filamentous tufts. 



2. The Jungiform papilla, found chiefly at the tip 



and sides of the tongue, are less numerous but 

 larger than the preceding and of a deep red 

 color. 



3. The circumvallate papilla, from eight to ten in 



number, are situated at the base of the tongue 

 arranged in the form of the letter V. They con- 

 sist of a central projection surrounded by a 

 wall or circumvallation from which they take 

 their name. 



The Peripheral End-organs. The Taste- 

 buds. Embedded in the epithelium covering the 

 mucous membrane not only of the tongue but of 

 the palate and posterior surface of the epiglottis are 

 small ovoid bodies which from their relation to the 

 gustatory nerves are regarded as their peripheral 

 end-organs and known as taste-buds or taste-beakers. 

 Each bud is ovoid in shape (Fig. 301). Its base rests 

 on the tunica propria; its apex comes up to the epi- 

 thelium, where it presents a narrow funnel-shaped 

 opening, the taste-pore. The wall of the bud is composed of elongated 

 curved epithelium. The interior contains narrow spin- 

 dle shaped neuro-epithelial cells provided at their outer 

 extremity with stiff hair-like filaments which project 

 into the taste-pore. 



The neuro-epithelial cells are in physiologic relation 

 with the nerves of taste. The terminal branches, after 

 entering the bud at its base, develop fine tufts which 

 come into contact with the cells. That the taste-buds 

 are connected with the nerves of taste is rendered prob- 

 able from the fact of their degeneration after division of 

 the nerves. 



The Taste Area. The taste area, though confined 

 for the most part to the tongue, extends in different in- 

 dividuals to the mucous membrane of the hard palate, 

 to the anterior surface of the soft palate, to the uvula, 

 the anterior and posterior half arches, the tonsils, the 

 posterior wall of the pharynx, and the epiglottis. 



The Taste Sensations. The sensations which arise 

 in consequence of impressions made by different sub- 

 stances on the peripheral apparatus of this area are in so 

 many instances combinations of taste, touch, temperature, 

 and smell that they are extremely difficult of classifica- 

 tion. Nevertheless six primary tastes can be recognized: 

 bitter, sweet, acid or sour, salt or saline, alkaline and metallic. Though 

 the contact of any bitter, sweet, acid, salt, etc., substance with any part of 



FIG. 30!; TASTE- 

 BUD FROM CIRCUM- 

 VALLATE PAPILLA OF 

 A CHILD. The oval 

 structure is limited to 

 the epithelium (e) 

 lining the furrow, 

 encroaching slightly 

 upon the adjacent 

 connective tissue (/); 

 o, taste-pore through 

 which the taste-cells 

 communicate with 

 the mucous surface. 

 (Ajter Pier sol.} 



