THE SPECIAL SENSES 



251 



the air sharply. The sense of smell seems to be nature's 

 sentinel to guard us against taking improper food into the 

 stomach and impure air into the lungs. 



Experiment 73. To show that we often fail to distinguish between 

 the sense of taste and that of smell. If we chew some pure roasted 

 coffee, it seems to have a distinct taste. Pinch the nose hard while 

 chewing it, and there is little 

 taste. Coffee has a powerful 

 odor but only a feeble taste. 

 The same is true of garlic, 

 onions, and various spices. 



Experiment 74. Light helps 

 the sense of taste. Shut the 

 eyes, and palatable foods taste 

 insipid. Pinch the nose, close 

 the eyes, and see how palatable 

 one half of a teaspoonful of 

 cod-liver oil becomes. 



Experiment 75. Close the 

 nostrils, shut the eyes, and 

 attempt to distinguish by taste 

 alone between a slice of an 

 apple and one of a potato. 



FIG. 154. Distribution of Nerves over 

 the Interior of the Nostrils. (Outer 

 wall.) 



A, branches of the nerves of smell ; B, nerves 

 of touch to the nostrils ; E, F, G, nerves 

 to the palate springing from a ganglion at 

 C; H, a branch of the facial nerve, from 

 which other branches, D, I, and /, spring 

 to be distributed to the nostrils. 



344. The Sense of Hear- 

 ing. We come now to a 

 special sense, which does 

 not tell us what is going 

 on in the outer world by 

 actual contact, as in touch or taste, nor by particles of 

 matter falling upon the ends of nerves, as in the sense 



of his master amid those of a hundred other people, and can track him for 

 miles, although he has been for hours out of sight. Hounds track the 

 fox or the deer by the sense of smell. Dogfish find their prey by the sense 

 of smell rather than by sight. 



