THE LUNGS 193 



the nose 'a tube extends to the eye to drain away tears, and 

 another opening extends into the antrum or cavity in the 

 upper jawbone. In the nose there are special nerves of 

 the sense of smell. (See p. 324.) 



331. The pharynx. The pharynx is the muscular bag 

 just back of the mouth, through which both food and air 

 pass. Air should always enter it from the nose. Just in 

 front of the pharynx upon each side is a fleshy body, look- 

 ing like an almond, and called the tonsil. Sometimes the 

 tonsils become very large in children and close the open- 

 ing into the nose, making it necessary to breathe through 

 the mouth. 



332. Adenoid vegetations. In the upper part of the 

 pharynx, just behind the opening of the nose, there often 

 grows a collection of soft, grapelike bodies, called ade- 

 noid vegetations. They close the opening to the nose and 

 compel a person to breathe through the mouth. They 

 begin to form during early childhood while the bones are 

 growing. The unnatural breathing and open mouth de- 

 form the upper jaw so that it becomes narrow and pointed. 

 The trouble is a serious one, for it compels mouth breath- 

 ing; it renders the child very susceptible to taking cold 

 and other infectious diseases; and it is the most common 

 cause of deafness, for it stops the Eustachian tube lead-, 

 ing to the ear. Often adenoids are associated with large 

 tonsils. 



When a child becomes grown, the adenoids often shrink, 

 and so cure themselves, but the deformed jaw lasts through 

 life. They can easily be broken down and removed, and 

 this should be done in every case. 



333. Mouth breathing. The mouth contains no means for 

 warming the air, or for screening out dust and disease germs, as the 

 nose has. So a mouth breather is very likely to take cold. When he 



ov. PHYSIOL. 13 



