THE SENSES 147 



The principal tastes are only four ; namely, sweet (tasted 

 chiefly by tip of tongue), sour and saline (sides of tongue), 

 bitter (tasted on the back of tongue) (Exp. 5). 



The nerves of smell end in the mucous membrane of the 

 upper half of the two nasal chambers ; \hzfibers are spread 

 over the upper proportion of the walls. The direct current 

 of air does not pass as high as these nerve endings ; hence 

 sniffing aids the perception of odors. This sense is able 

 to bring up the associations of early life more powerfully 

 than any of the senses. The odor of a flower like one 

 that grew in an old garden can almost restore the con- 

 sciousness of the past. We smell gases only ; - solids and 

 liquids cannot affect this pair of nerves (Exp. 8). 



Flavors. The tastes that we call flavors are really 

 smells. We confuse them with taste, because they accom- 

 pany food that is in the mouth. Name some foods that 

 seem " tasteless " when one has a severe cold in the head. 

 Why is this ? Some of the most repulsive drugs can be 

 easily swallowed if the nose is held (Exp. 6 and 7). 



Hygiene of the Senses of Taste and Smell. A savage or a beast 

 uses the senses of taste and smell to find out whether things are good 

 to eat or not. If a civilized man's senses are not perverted, and he eats 

 only simple foods that have a pleasant taste, they will not injure him or 

 cause him sickness. Things that are poisonous usually have unpleasant 

 tastes and often have unpleasant odors. These senses are naturally 

 of wonderful delicacy. They can be cultivated to a still more remark- 

 able degree, or they can be blunted and almost destroyed. Chronic 

 catarrh dulls or destroys the sense of smell. The loss or even the 

 weakening of the perception of flavors is an injury to the working of 

 the closely related sense of taste. When a person loses the enjoyment 

 of delicate flavors, he wants food to have strong seasoning and more 

 decided taste to prevent it from being insipid. Everything must be 

 either very greasy or very sweet or very salty or very sour, to please his 

 degenerate senses. Wheat, corn, and other grains have each its own 

 pleasant taste, yet such persons must have lard in their bread because 

 they are not capable of appreciating anything with a delicate taste. In 



