66 PLAIN FACTS FOR OLD AND YOUNG 



The ear of a fish consists of a small sac, containing 

 two or three chalky masses called ear bones, placed in 

 a chamber adjacent to a sac containing the ear fluid 

 and nerves of hearing. The fish's ear is entirely in- 

 closed in a hollow in the skull. It hears by means of 

 the vibration of the water, which is communicated to 

 the bones of its head, thence to the ear bones, and then 

 from these to the delicate sac from which the nerves 

 of hearing convey the impression to the brain. 



The human ear, consisting of like essentials, is 

 much more complicated in its structure. There is, 

 within a hidden recess in the skull, a curiously shaped 

 sac filled with fluid, and containing a number of minute 

 ear stones. This sac is connected by means of a chain 

 of bones with a vibrating membrane, which closes the 

 end of the canal connected with the external organ 

 ordinarily known as the ear. Sounds are produced by 

 vibrations in the ear. These vibrations are gathered 

 by the external ear, and cause vibration of the mem- 

 brane, which, from its striking resemblance to that of 

 a drum, is called the drum membrane. This vibration 

 is carried by the chain of bones across the cavity in 

 which they are placed, termed the drum cavity, to the 

 delicate sac, within which are found the ear stones and 

 the nerves of hearing. The little ear stones dance up 

 and down upon the ends of the nerves, and produce 

 sensations which are carried from the ear to the brain. 

 The vibrations produced are known as sound. 



The Nose.— The nose, one of the most conspicuous 

 features of the face, though one of the most neglected 

 organs of the body, is useful as well as ornamental, 

 and worthy of at least a moment's notice. The primary 

 office of the nose is to receive air to supply the lungs. 

 For this purpose it has two openings in the face, which 



