226 



PHYSIOLOGY. 



Fig. 1. 



External Ear and Muscles. 



seals and whales, are destitute of it. Indeed, as water is a 

 much better conductor of sound than air, there would seem 

 to be little occasion for the external ear in them ; but they 

 suffer in consequence, when they attempt to live with their 

 heads out of water. Owing to this obtuseness of hearing 

 in the whale, he is easily approached by the whaler, and be- 

 fore he hears the oars of his enemy, the harpoon is fixed 

 into his unwieldy carcass. In like manner, the walrus and 

 the seal remain unconscious of the footsteps of their foe, till 

 it is too late to retreat. In land animals that are timid, as 

 the hare and rabbit, the ear is very large, so that they may 

 be apprized of the approach of their enemy in time to flee 

 to a place of safety. I 



4. The Tube of the External Ear. This is the passage, 

 called by anatomists meaius auditorius externus, which ex- 

 tends from the outer ear to the tympanum or drum, which is 

 stretched across its inner end. This passage is about ten 

 lines, or nearly an inch in length ; and pursues a somewhat 

 winding course inwards, a little forwards and downwards ; 

 its external portion being composed of cartilage, and its in- 

 ternal of bone. The width, as well as tension of this tube, 

 are effected by the motions of the jaw, ns any one can learn 



