RESPIRATORY APPARATUS. 95 



pronounced at inspiration, and results from a narrowing of 

 the nasal chambers due to the presence of tumors, swelling 

 of the alae of the nostrils, septum or chonchae, enlargements 

 of the turbinated bones or fractures of these bones, fractures 

 of the nasal bones, or deposits of exudate on the mucous 

 membrane. Depending upon the condition of the mucous 

 membrane, the stenotic sound may be accompanied by either 

 moist or dry rattling noises. 



2. Snoring takes place when the act of breathing is ef- 

 fectednhrough the open mouth, the soft palate undergoing .a 

 fluttering motion. In swine and dogs it occurs when the 

 lumen or the nasal cavities is contracted by swelling or thick- 

 ening of the mucous membrane. Snoring is also noted in the 

 ox when the retro-pharyngeal lymph glands are swollen or 

 enlarged ; further in the course of parturient paresis. Horses 

 under chloroform sometimes snore. 



3. Rattling is a stenotic laryngeal sound which occurs 

 when the vocal cords are relaxed. It is heard in severe in- 

 flammations of the larynx or of the neighboring pharyngeal 

 mucous membrane; phlegmon of the pharynx and edema of 

 the glottis. 



4. "The Mucous Click" {klatschcndcr Xasalton) is a 

 peculiar metallic, short expiratory sound first described by 

 Dieckerhofif. It occurs during an inspiratory-expiratory dys- 

 pnea if the nasal mucous membrane is very moist. At a 

 forced inspiration that part of the nasal mucous membrane 

 which unites w^ith the skin of the false nostril, is sucked 

 against the opposite wall to which it adheres for a moment; 

 when an expiration takes place this adhesion is broken, caus- 

 ing a metallic "slapping" tone to be emitted. This sound is 

 of no significance. 



5. The most important pathological re- 

 spiratory t o n e is the stenotic laryngeal tone. Normally 

 the sound emitted by the larynx is a soft stenotic sound audi- 

 ble when the ear is placed bver the organ. [It can be imitated 



