152 THE WONDERFUL HOUSE THAT JACK HAS 



But surely it cannot be harmful to breathe through 

 the mouth when the air is not cold and we cannot see 

 any dust in it. On the contrary, such a practice can 

 do much harm. In the first place, although the air 

 looks clean, it is scarcely ever free from dust. In the 

 second place, the slight amount of resistance offered 

 while breathing through the nose helps to keep the 

 chest properly developed, while in mouth breathers the 

 air gets in so easily that the chest muscles have little 

 to do and flat chests consequently result. Then, even 

 if no injury should result from putting the mouth to a 

 use for which it was not intended, harm is likely to 

 come from not using the nose as the highway for which 

 it was made. We know that when a path or road 

 remains unused, grass and weeds will grow up in it. 

 So when the natural roadways of the air to the trachea, 

 the nose passages, are not made use of, weeds in the 

 form of polypi and other growths may spring up in the 

 mucous membrane. These block the unused passages, 

 and, in the worst cases, even cause deafness. 



Growths called adenoids are very common in chil- 

 dren. They plug both nostrils, causing all the evils 

 of mouth breathing and often greatly lowering the 

 general health. If large enough to be obstructive, 

 they should be removed by a physician, for no child 

 having them can thrive. Adenoids are among the 

 most common causes of mouth breathing. 



The mouth-breathing habit, whether it results from 

 adenoids or some other cause, not only may weaken 



