316 



in-: .{RING. 



may ruin the eyes by wearing glasses when they are not 

 needed. Sight is priceless. 



The Sense of Hearing. The ear passages are inclosed 

 by the hard bones of the head. The ear is, in consequence, 

 difficult to dissect. It is very desirable to have a model of 

 the ear, and a good model may be bought for less than ten 

 dollars. The ear may be dissected in a cat or rabbit by fol- 



Stirrup Anvil 



Semicircular Canals 



PHARYNX 



Fig. 93. Diagram of the Ear. 



lowing the accompanying description. It will take time and 

 patience to trace all the parts. 



The ear is a much more complicated organ than would 

 naturally be supposed. The parts of the ear are the External, 

 Middle, and Internal ear. The external ear gathers the sound- 

 waves and directs them into the opening of the ear, but the 

 loss of the external ear does not seriously interfere with hear- 

 ing. The hole leading inward from the ear extends a little 



