DISEASES OF THE KESPIRATORY ORGANS. 359 



tinct over the middle and upper third of the chest. In the ox it 

 is heard lower down. The bound produced by percussion in the 

 normal chest is of a resonant character. It is very clear immedi- 

 ately behind the shoulder to the twelfth or thirteenth rib, where 

 it gradually diminishes. 



The abnormal sounds heard in the thoracic cavity are, first, a 

 sonorous, murmuring sound, caused by narrowing of the large 

 bronchial tubes. This is termed rhonchus. It may be heard in 

 front of the chest and behind the shoulder. 



Sibilant Rale. — By this is meant a whistling, hissing, click- 

 ing, wheezing sound. It is associated with bronchitis, and is heard 

 in the region of the bronchial tubes. 



Mucous Rhonchus, or Rale. — The bursting of bubbles of 

 some size, varying in number, modified by coughing and expecto- 

 ration. The sound is due to bubbling of air through the liquid. 

 This is seen in the moist stage of bronchitis. 



Crepitations. — This sound is compared with that produced 

 by rubbing slowly and firmly betAveen the finger and thumb a 

 lock of one's hair near the ear. This is best heard in the lower 

 third of the chest. 



TUBAL OR BRONCHIAL SOUND. 



When this sound is heard over the inferior portion of the 

 thorax, it indicates some degree of consolidation of the lung. 



Absence of Sound. — When this occurs, it indicates that the 

 exudation is excessive in quantity, and that effusion has taken 

 place in tke thorax. 



PLEURAL SOUNDS. 



There may be heard a rubbing or grating sound during inspi- 

 ration and expiration. It is caused by rubbing together of the 

 two opposed surfaces of the pleura, chiefly heard at the lower part 

 of tke chest. 



