298 SENSE OF SMELL. 



" taste buds," connected 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 " pal- 

 atable," or " unpalatable," the sense of taste in the palate is 

 only feebly developed. 



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. 

 Insoluble substances give no taste. 



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 indicated. 



It is said that the temperature of about 40 degrees 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. 



The tip of the tongue seems to be most sensitive to sweets 

 and salines, the back part to bitters, and the sides to acids. 



The Sense of Smell. " The sense of odor gives us in- 

 formation as to the quality of food and drink, and more espe- 

 cially as to the quality of the air we breathe. Hence we find 

 the organ placed at the opening of the respiratory passages 

 and in close proximity to the organs devoted to taste. Taste 

 is at the gateway of the alimentary canal, just as smell is the 

 sentinel of the respiratory tract ; and just as taste, when com- 

 bined with smell to give the sensation we call flavor, influences 

 the digestive process, and is influenced by it, so smell influ- 



