24 ORGANS OF THE SENSES NOSE, MOtJTII DIAGRAM 2. 



form : one resembles a hammer, the second an 'anvil, and the 

 third a stirrup . They are known by these names. Lastly we 

 find in the internal ear a narrow canal twisted into a spiral like 

 a snail-shell, and called, on this account, the cochlea. 



After certain diseases, the internal ear is destroyed, and 

 deafness results. If a child is born deaf, it hears nothing, and 

 as it does not hear words, it cannot repeat and learn to say them, 

 and is then dumb. Those who are born in this state are called 

 deaf-mutes. 



The nose. The nose serves for respiration as well as the 

 mouth ; and can also perceive odours. It communicates at the 

 back with the throat, and we can therefore return smoke taken 

 by the mouth through the nose, and can also swallow water 

 which lias been snuffed up strongly. The whole space 

 between the nose and the throat is called the nostrils. They are 

 prolonged by cavities which rise as far as the forehead, and 

 hence it is supposed, when an irritating powder such as 

 tobacco, pepper, or camphor has been taken, that it has pene- 

 trated to the brain ; but this is a mistake, for the brain is 

 always separated from the nose by bones, and nothing can 

 penetrate to it. We often speak of a cold in the head ; bu^ 

 it is not the brain which is affected, it is only the lining mem- 

 brane of the nostrils, or the pituitary membrane. The brain is 

 separated from the nose, and is not affected, and therefore cold in 

 the head is never a serious complaint. 



TJie mouth serves to breathe, eat and speak ; the mucous mem- 

 brane, or skin which covers the inside of th^ mouth, also serves 

 to taste our food. The flavour is perceived by small papilli on 

 the tongue, each of which is connected with a nervous thread, 



ORGANS OF THE YOICE. DIAGEAM 2, 



The voice is formed by the air driven from the lungs, where 

 it passes into the larynx. The larynx is situated above the 



