vm TASTE 361 



nose is held tightly pinched, it is very diflBcult to distinguish 

 the taste of various objects. An onion, for instance, 

 the eyes being shut, may then easily be confounded with 

 an apple. This explains the not uncommon device of 

 pinching the nose when taking nauseous medicine. 



But the so-called "tastes" which are thus affected by 

 the absence of smell ought rather to be spoken of as 

 "flavours" than as tastes. They are distinctly due to 

 the odoriferous particles the substances emit, and thus 

 people are in the habit of "sniffing" a glass of wine in 

 order to appreciate what they call its taste. True taste is 

 independent of smell, as in the case of sugar or quinine. 

 When we come to investigate the matter closely, we find 

 that the various real tastes may be arranged under four 

 heads : these are — sweet, bitter, sour or acid, and salt. 

 These tastes are not excited equally all over the surface 

 of the tongue. Thus the tip is most sensitive to sweet 

 substances, and the back to bitter, while the sides of 

 the tongue most readily respond to acids. 



The sense of taste is most acute at medium temperatures, 

 such as 20' — 30 C. (68' — 95' F.), and substances to be 

 tasted must be in solution. 



8. The Sense of Smell. — The organ of the sense of 

 smell is the delicate mucous membrane which lines the 

 upper part of the nasal cavities. In this part the mucous 

 membrane is distinguished from the rest of the mucous 

 membrane of these cavities — firstly, by the character of 

 its cells and by possessing no cUia ; secondly, by receiving 

 a large nervous supply from the olfactory, or first, pair of 

 cerebral nerves (see Lesson XI.), as well as a certain 

 number of filaments of the fifth pair, whereas the rest 

 of the mucous membrane is supplied from the fifth pair 

 alone. 



Each nostril leads into a spacious nasal chamber, 

 separated, in the middle line, from its fellow of the other 

 side, by a paitition, or septum, formed partly by cartilage 

 and partly by bone, and continuous with that partition 



