134 CLINICAL DIAGN-OSTICS, 



when a large air-containing cavern is in direct communication 

 with a bronchus. Forcible percussion causes some of the air 

 to be suddenly driven out of the cavern into the communicat- 

 ing bronchus, thus inducing this peculiar resonance. The 

 cracked-pot resonance, however, does not 

 always indicate the presence of a cavern 

 inthelung. 



3. In pneumothorax. 



4. In prolapsus of bowel into the thoracic 

 cavity through the ruptured diaphragm, 



X. Auscultation of the lungs. 



During breathing, when the air enters the lung and causes 

 it to move, sounds are produced. The occurrence and charac- 

 ter of these sounds furnish important data in regard to the 

 condition of the air passages and of the surface of the lung. 

 The intensity of the sounds varies with the depth of the res- 

 pirations ; when the breathing is forced they are augmented. 

 Therefore, to make them more audible it is sometimes advisa- 

 ble to exercise the patient before auscultating. The sounds 

 may also be made more distinct by holding the nostrils shut 

 for a few moments. The partial closing of the nostrils, how- 

 ever, recommended by some, is not admissible, as it induces 

 a stenotic tone which might prove misleading. 



a. The vesicular murmur. In auscultating the thorax 

 over healthy lung, we perceive a soft, sipping sound, the vesic- 

 ular or alveolar murmur. The sound can be imitated by 

 softly pronouncing the letter "v." It begins with the inspira- 

 tion, increasing as the inspiration continues, and becomes at 

 expiration, a fainter, shorter sound, having the character of a 

 softly aspirated letter "f." 



As a rule the rnurmur is softer and less distinct in the 

 horse than in the ox. 



As with the laryngeal respiratory sound, so are other 

 sounds originating in the upper air passages transmitted to the 



