TASTE, SMELL, AND HEARING. 



305 



The External 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 hearing. The passage leading inward from the ear 

 extends about an inch, and is then completely shut off 

 from the cavities beyond by a thin membranous partition, 

 the tympanic membrane or drum skin. The skin of the 



Stirrup Anv 



Semicircular Canals 



COCHLEA 



PHARYNX 



Fig. 93. Diagram of the Ear. 



ear dips into and lines the external tube, and continues as 

 a very thin layer over the membrane of the tympanum. 

 The auditory meatus, as this passageway is called, is 

 guarded by hairs, and is further protected by wax secreted 

 by glands of the lining. 



The Middle Ear. Beyond the membrane of the tym- 

 panum is a cavity called the middle ear. Extending across 

 the cavity of the middle ear is a chain of very small bones, 

 the hammer, anvil, and stirrup, the hammer being attached 



