576 



COMPARATIVE PHYSIOLOGY. 



certain animals with rough tongues, the papillae, certain of 

 them at least, answer to the hairs of a brush for the cleansing 

 and general preservation of the coat of the animal in good con- 

 dition. We may, perhaps, speak of certain fundamental taste- 

 perceptions, such as sweet, bitter, acid, and saline. Certainly 

 the natural power of gustatory discrimination is considerable; 



' J / 't ^* ^ \ 



5V 



Fig. 420.— Papillae of tongue (after Sappey). 1, circumvallate papillse; 3, fungifonn 

 papillae; 4, fliiform papillae; 6, gland^ at base of tongue; 7, tonsils. 



and. as in the case of tea-tasters, capable of extraordinary culti- 

 vation. All parts of the tongue are not equally sensitive, nor 



