68 



HUMAN PHYSIOLOGY 



CHAP. 



freely. A child may be so accustomed to improper 

 clothing that slowly and gradually his chest becomes 

 permanently deformed. 



Careless positions in standing and sitting may cause 

 the chest to become so deformed as to make natural 

 breathing impossible. When a person becomes round- 

 shouldered and flat-chested the upper part of the thorax 

 cannot enlarge as it should. The result is that the apex 



Left curz>e. 



Round shoulders. 



FlG. 33. Showing deformed chests. (Drawn by H. Meyer from photographs.) 



of each lung remains unused. A pupil who sits day 

 after day at a desk that is either too high or too low soon 

 finds that one shoulder is higher than the other and that 

 the spine is curved to the right or to the left. Under 

 any of these conditions the chest cannot expand as it 

 should, and lung diseases are easily contracted. 



Sometimes persons are born with small or deformed 

 chests and are more likely to contract the diseases 

 which attack the lungs. Consumption is probably 

 seldom if ever inherited, although weak and imperfectly 



