PHYSICAL DIAGNOSIS OF THE LUNGS 127 



the diseased lolndes are located among clear tissue that the air is passing 

 into, and where the true character of the respiratory bruit is not heard on 

 account of the loud rattling of the air going through the contracted 

 bronchial tubes. Indistinct respiratory sounds are also heard where there 

 is more or less mucus in the bronchial tubes, and after the animal has 

 had a coughing spell the true bronchial sound is heard. 



Irregular bronchial sounds (rattling bruits) are caused by the move- 

 ment of the mucus or fluids that are in the air-passages, being carried 

 to and fro by the passage of air. The}^ are dry (snoring, wheezing) where 

 a small ciuantity of sticky mucus collects in the bronchial tubes, as is seen 

 in some catarrhal affections and in cases where the mucous membrane is 

 considerably swollen. The snoring sound is generally heard in the large 

 bronchial tubes. The wheezing sounds occur in the smaller bronchial 

 tubes. A spell of coughing produces considerable change in the character 

 of the slight, rattling sounds of the chest. The rattling sounds are moist 

 Avhen the secretions are lic|uid; the thicker they are the duller the bruits 

 become. We hear moist, rattling sounds when the secretions are col- 

 lected in the large bronchi; this sound is also heard when there are caver- 

 nous portions in the lungs. We find much less when this is the case in 

 the middle bronchi, and a very low bronchial bruit when the small 

 In-onchi are involved. By this means we can distinguish in what posi- 

 tion the irritation lies in the bronchi; this is rather important in diagnos- 

 ing a case of bronchitis. AVhen the fine bronchioles are involved it has a 

 crackling or crepitant sound and sibilant bruits; these are only heard 

 during inspiration. This sound may sometimes be heard in the alveolar 

 passages and in the alveoli themselves, when they are filled with mucus 

 or closed up, and where the air can reach them only by strong inspiration. 

 This is seen in the first and third stages of croupous pneumonia, in oedema 

 of the lungs, and in capillary bronchitis; in the last, the crepitation is 

 mixed with an irregular rattling sound. We find also the friction sound 

 of the pleura; this is not heard in the normal condition, but in disease; it 

 is either crepitating, scraping, or scratching. It is heard in pleurisy; as a 

 rule it is louder on inspiration than expiration. This sound is produced 

 by collections of fibrinous accumulations on the pleura. These sounds 

 are not heard when the pleura is separated by an exudate. The sound is 

 plainest at the commencement of the disease, and when the exudate is 

 being absorbed. This sound is not altered by coughing, and in this way 

 can be distinguished from rattling sounds which are heard when it is a 

 case of pleuro-pneumonia. The rubbing sound caused by the broken 

 ends of a fractured rib is indicated by the crepitation on movement of the 

 ends of the rib. 



