190 THE SPECIAL SENSES. 



cells covering the nerves, it must either be liquid in form, 

 or readily soluble in the watery secretion of the mouth, 

 the saliva. The tongue must be moist also. If the sub- 

 stance be insoluble, as glass or sand, or the tongue dry, the 

 sense of taste is not awakened. In sickness, when the 

 tongue is heavily coated, the taste is very defective, or, as 

 is frequently expressed, "nothing tastes aright." 



33. All portions of the tongue are not alike endowed 

 with the sense of taste, that function being limited to the 

 posterior third, and to the margin and tip of this organ. 

 The soft palate, also, possesses the sense of taste ; hence, 

 an article that has an agreeable flavor may very properly 

 be spoken of as palatable, as is often done. All parts of 

 the tongue do not perceive equally well the same flavors. 

 Thus, the front extremity and margin, which is the por- 

 tion supplied by the "fifth pair" of nerves, perceives more 

 acutely sweet and sour tastes; but the base of the tongue, 

 supplied by the glosso-pharyngeal nerve, is especially sen- 

 sitive to salt and bitter substances. The nerve of the front 

 part of the tongue, as before stated, is in active sympathy 

 with those of the face, while the relations of the other 

 nerve are chiefly with the throat and stomach ; so that 

 when an intensely sour taste is perceived, the countenance 

 is involuntarily distorted, and is said to wear an acid ex- 

 pression. On the other hand, a very bitter taste affects 

 certain internal organs, and occasions a sensation of nau- 

 sea, or sickness of the stomach. 



34. Relations of Taste with other Senses. 

 Taste is not a simple sense. Certain other sensations, as 

 those of touch, temperature, smell, and pain, are blended 



-and confused with it; and certain so-called tastes are really 

 sensations of another kind. Thus an astringent taste, like 

 that of alum, is more properly an astringent feeling, and 



33. Portions of the tongue endowed with taste? - Where else does the sense 

 !ode ? What is stated in respect to sweet and bitter flavors ? Reflex effects men- 

 tioned ? 



34. What is stated of the relations of taste with other senses ? 



