AUSCULTATION. 507 



passage is otherwise diminished, as by a polypus or foreign 

 object, a loud blowing sound is induced, which may exist in 

 one or in both nostrils. If the passage is still farther 

 diminished, the sound acquires a whistling character. These 

 noises generated in the nose may be distinguished from 

 those originating in the larynx or elsewhere, by their gradu- 

 ally decreasing in pitch, as examined first on the nasal bones, 

 next over the larynx, and latterly over the trachea and 

 thorax. Sounds generated elsewhere often appear very loud 

 when heard at the nostrils, but may be readily referred to 

 their proper place, by auscultating successively the walls of 

 the different portions of the respiratory tract. 



Larynx. When the ear is applied over the larynx, or 

 upper end of the trachea, in a healthy animal, a soft and 

 very slight murmur is observed. 



In a diseased condition, when there is a diminished orifice 

 for the transmission of air, a dry whistling sound is pro- 

 duced. This symptom is a result either of distortion, of 

 mechanical compression, or of atrophy of the laryngeal 

 muscles, with imperfect separation of the vocal cords, as a 

 result of lesion of the recurrent nerve. If the subject is put 

 to severe exercise, the sound becomes louder and assumes a 

 sonorous character, to which the name of roaring has been 

 given. When the orifice is smaller the tone is shriller, and 

 the condition is known as whistling. The above refers to 

 dry sounds produced in the larynx, but a soft whistling 

 may likewise exist, as in the case of acute laryngitis, when a 

 considerable secretion of mucus has taken place. This may 

 intermit on the occasion of the larynx being cleared by 

 coughing. By auscultating the larynx and trachea, the 

 sound can easily be localised. 



Windpipe. The trunk of the trachea generally yields no 

 sound. At its superior extremity may be heard a modified 



