vi HYGIENE OF RESPIRATION 67 



it enters ; or the lower sash may be raised and means 

 provided for directing the entering air upward. These 

 are inexpensive but quite effective means of ventilation. 

 61. Chest Freedom. The air we, breathe may be 

 perfectly pure and fresh, and yet the cells of the body 

 may suffer because they do not receive enough oxygen. 

 You remember that the chest acts like a pump which 



Natural. Deformed. 



FIG. 32. Showing a natural and a deformed chest. (From Kellogg's " Out- 

 line Studies.") 



at every natural inspiration pumps about thirty cubic 

 inches of air into the lungs. Now, if the chest does not 

 do its work as it should, an abundance of good whole- 

 some air may be present, and yet only a small amount 

 get into the lungs. How may the work of the chest be 

 hampered ? In the first place, by clothing that is im- 

 properly made or that does not fit. Clothing may be 

 so tight about the waist that the chest cannot enlarge 



