RESPIRATION 



389 



>ounded by the vocal bands, is also triangular in shape, though in this case 

 he base is directed backward, and the apex forward. (See chapter on Voice 

 jid Speech.) 



The introduction of the vocal bands narrows at this level the air-passage 

 md to some extent interferes with the free entrance of air. According to 

 he investigations of Semon, the area of the air-passage above and below 

 he phonatory apparatus is about 200 sq. mm.; while the area bounded 



the vocal apparatus is but 155 sq. mm. during quiet respiration. 



FIG. 182. Human larynx, trachea, bronchi, and lungs; shoeing the ramification of the bronchi, 

 and the division of the lungs into lobules. 



