134 CLINICAL DIAGNOSTICS. 



ing in intensity as the inspiration progresses ; coughing may 

 temporarily remove them. The intensity of rales depends upon 

 the extent of the disease and the topographical position of the 

 diseased part. 



Moist rales originate from the to-and-fro movement of 

 mucus [pus, blood, liquid exudate] , the forming and bursting 

 of bubbles, and the vibrations produced by these acts. Accord- 

 ing to whether rales attend vesicular, bronchial or amphoric 

 respiration their tone will vary; metallic rales as a rule accom- 

 pany bronchial respiration. 



By crepitant rales', we understand very fine, crackling 

 noises, which resemble the sound heard when the ear is rested 

 very lightly upon the haired skin of an animal. Taking their 

 origin into consideration they can be grouped with neither the 

 moist nor the dry rales. They originate from a separation, at 

 inspiration, of the adhering walls of the bronchi and vesicles. 

 They appear in bronchiolitis, pulmonary edema and in the 

 exudative (early) stage, and last stage (resolution) of fibrin- 

 ous pneumonia (contagious pleuropneumonia of the horse). 



2. Dry rales appear if a small quantity of a tough 

 bronchial secretion is present, or if the mucous membrane is 

 greatly swollen. These conditions produce more or less 

 roughening of the mucous membrane, the projecting irregu- 

 larities of which vibrate and cause sounds during in- and 

 expiration. Dry rales are, therefore, of a sonorous, humming, 

 hissing, squeaky, zchistling (sibilant) character. Thev mo?t 

 commonly attend chronic diseases : chronic bronchitis, compres- 

 sion of the bronchi by nodules (tuberculosis, chronic pneu- 

 monia) and tumors (echinococci). In the echinococcus dis- 

 ease of the ox the rale has a peculiar (quurksend) character. 



On account of their origin it is better to designate dry 

 rales as stenotic sounds. 



A wheezing, crackling, whistling or piping, rale-like 

 sound is heard in interstitial emphysema of the lungs. It is 

 most pronounced during expiration. 



