BREATHING AND VENTILATION 61 



breathe through the mouth from one or more of the 



following causes: (i) They may have abnormal spongy 



growths in the back part of the nose. These are called 



adenoids. They keep the air from going through the 



nose, and so the child who 



has them is compelled to open 



its mouth to get air. In ad- 



dition, adenoids interfere with 



the flow of blood to the brain 



and cause indistinct pronun- 



ciation of words, listlessness, 



inattention, poor memory, par- ADENOIDS 



tial deafness, and frequent 

 colds, or earache. The signs 

 indicating the presence of adenoids are parted lips, 

 prominent eyeballs, a narrow, high-arched roof of the 

 mouth, and nasal speech. Adenoids can easily be re- 

 moved by a physician. (2) Colds and catarrh cause 

 the nose to be clogged by the slimy fluid secreted by 

 the mucous membrane, so the air cannot easily pass 

 through. (3) Carelessness and indifference on the part 

 of many are also causes of mouth breathing. 



44. Effects of Mouth Breathing. (a). The mouth 

 passage is much shorter for the flow of air than by way 

 of the nose, so the air breathed through the mouth is not 

 warmed before reaching the throat and lungs and hence 

 irritates the vocal cords and causes coughing, and finally 

 a husky voice will result. In cool weather colds may re- 

 sult from mouth breathing, (b) The mouth does not 

 strain out the dust and germs as the hairs and mucous 

 folds in the nose do, and so the throat and lungs become 

 irritated and diseases may be contracted from the inhaled 

 germs. The dust in the lungs will also hinder the flow 



