-572 THE HUMAN BODY. 



except as aiding in the selection of food, and for that pur- 

 pose they are not by any means safe guides at all times. 



Many so-called tastes (flavors) are really smells; odorif- 

 erous particles of substances which are being eaten reach the 

 olfactory region through the posterior nares and arouse sen- 

 sations which, since they accompany the presence of objects 

 in the mouth, we take for tastes. Such is the case, e.g., 

 with most spices; when the nasal chambers are blocked or 

 inflamed by a cold in the head, or closed by compressing 

 the nose, the so-called taste of spices is not perceived when 

 they are eaten; all that is felt, when cinnamon, e.g., is 

 chewed under such circumstances is a certain pungency due 

 to its stimulating nerves of common sensation in the tongue. 

 This fact is sometimes taken advantage of in the practice 

 of domestic medicine when a nauseous dose, as rhubarb, is 

 to be given to a child. Tactile sensations play also a part 

 jn many so-called tastes. 



Most persons taste bitters best with the back of the 

 tongue and sweets towards the tip; but this is not constant. 

 The curious interference of tastes which takes place when 

 the acidity of a sour body is covered by adding a sweet one, 

 which does not in any way chemically neutralize the acid 

 (when sugar is put on a lemon for example), needs explana- 

 tion. 



