302 PHYSIOLOGY. 



pillae, arranged like a letter V with its apex toward the base 

 of the tongue. These are the circumvallate papillae, each 

 having around it a deep circular furrow. 



The Nerve Supply of the Tongue. On the sides of 

 this furrow are small oval bodies, called "taste buds," con- 

 nected with the ends of the nerves of taste. The nerves 

 of taste are the glosso-pharyngeal, or ninth cranial nerves, 

 distributed to the back part of the tongue, and a branch of 

 the fifth pair of nerves, the gustatory, to the front part. 



Although we ordinarily speak of an article of food as 

 " palatable," or " unpalatable," the sense of taste in the 

 palate is only feebly developed. The tip of the tongue 

 seems to be most sensitive to sweets and salines, the back 

 part to bitters, and the sides to acids. 



Solution Necessary for Tasting. Substances must be 

 dissolved before they can be tasted. If the tongue be 

 wiped dry, and a few grains of salt or sugar be placed on 

 it, the taste will not be perceived for a little time. Insol- 

 uble substances give no taste. 



Flavors. What we call flavors affect us more through 

 the sense of smell than through taste. If the nose be held 

 shut, and we are careful about breathing, a piece of onion 

 placed on the tongue does not produce what we usually 

 call the taste of the onion. We may thus get rid of the 

 disagreeable part of taking certain medicines. Let the 

 student experiment with various substances as above in- 

 dicated. 



Effect of Temperature on Taste. It is said that the 

 temperature of about 40 F. is most favorable for tasting, 

 and after rinsing the mouth with very hot or very cold 

 water, such bitter substances as quinine will have only a 

 trace of their usual taste. 



