INSPIRATORY APPARATUS. 131 



may also be made more distinct by holding the nostrils shut 

 for a few moments causing the patient to become dyspneic. 

 The partial closing of the nostrils, however, 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 murmur 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 

 lungs. These are rattling throat sounds, wheezing, groaning, 

 etc. Their appearance in the chest has no diagnostic signifi- 

 cance. 



An exaggerated vesicular murmur occurs: 



1. If the respirations are intensified, therefore in physio- 

 logical and pathological dyspnea. 



2. If it is compensatory; that is, if one portion of the 

 lung is required to perform extra work for another portion 

 which is diseased and incapable of taking part in the respira- 

 tory act. [For instance, where one lung does the duty of its 

 fellow which is diseased.] 



3. If a bronchitis is setting in, the lumen of the bronchi 

 being contracted by swelling of, or collections of exudate on, 

 the mucous membrane. The exaggerated vesicular murmur 

 in such cases is a symptom of great diagnostic importance. 



A diminished or feeble vesicular murmur occurs : 



1. If the thoracic wall is thickened from fat accumula- 

 tions or disease : swelling, neoformations. 



2. If the air cannot enter the vesicles 



