A STUDY OF THE SENSES 295 



or toadstool. They are less numerous than the filiform 

 papillae, but can be easily recognized on the sides and top 

 of one's tongue as rounded elevations of a deep red color 

 (see Fig. 27). Near the back of the tongue are eight to twelve 

 papillae of large size. Each is situated in a cup-shaped depres- 

 sion, and hence is surrounded by a ditch, outside of which is 

 a wall of mucous membrane. From this fact these large ele- 

 vations are known as cir-cum-val'late papillce, (Latin circum- 

 vallare = to surround with a wall). 



B \ * 

 C 



FIG. 132. Diagram of a Circumvallate Papilla, and of Taste Buds. 



A = section of a circumvallate e = epidermis. 



papilla. m = projecting hair. 



B = two taste buds. n = four inner cells of bud. 



c = outer or protective cells. t = taste buds. 



d = dermis. x = nerve fibers. 



The Taste Buds. In the mucous membrane which covers 

 the fungiform and circumvallate papillae are little groups 

 of cells arranged in layers something like the leaves in a 

 bud. The outer cells of each taste bud form a protective 

 covering for the inner taste cells. The latter are spindle- 

 shaped ; their outer ends project from the taste bud as hair- 

 like processes, while the inner portion of each is connected 

 with fine branches of the fifth or ninth pairs of cranial nerves. 

 Taste buds like those on the papillae are also scattered here 

 and there over the surface of the tongue and the palate. 



Sensations of Taste. If I close my eyes and tightly hold 



