152 APPLIED PHYSIOLOGY 



upon the tongue. A substance dissolves in the saliva and 

 soaks through the epithelium of the tongue, and touching 

 the nerves produces the sense of taste. A substance that 

 will not dissolve in water has no taste. 



The sense of taste tells us what food is good for us. 

 Unwholesome or spoiled food generally has a bad taste. 

 We can learn to like some things that are not good for us. 

 Tobacco does not taste good at first, but men learn to like 

 it. We never tire of the taste of wholesome food, but 

 when we get too much sweets or candy, their taste makes 

 us sick. Even if a thing tastes good at first, its taste may 

 afterward show it to be unwholesome. 



We should not injure the nerves of taste by using 

 tobacco or alcohol. Even pepper and spices may injure 

 the taste so that we cannot tell when food is bad. 



Sometimes the senses of smell and taste blend together. 

 If the sense of smell is lessened, as by a cold in the head, 

 coffee does not taste so good as it should. If the nose is 

 stopped, persons can scarcely recognize the taste of onions. 



SUMMARY 



1. Anything touching the nerves produces a feeling of 



touch, or of pain or of temperature. 



2. Touch tells us about the shape, hardness, smoothness, 



and similar qualities of objects. 



3. Pain tells us that something is harming the body. 



4. Light passes into the eyeball and forms a picture upon 



nerves, and thus produces the sense of sight. 



5. Muscles turn the eye about, lids protect it, and tears 



wash away dust from it. 



6. Too bright a light harms the eyes. 



7. Air waves pass into the tube of the outer ear, and are 



carried across the middle ear by a chain of bones to 



