Auscultation. 197 



distinctly than in the horse. After the lapse of twelve, twenty- 

 four or forty-eight hours the friction sound disappears, the sur- 

 faces of the pleurae being separated by the liquid effusion, but it 

 may reappear when the fluid is absorbed in the process of recov- 

 ery. Sometimes the friction is further manifested by vibration 

 of the walls of the chest perceptible to the touch. 



The creaking sound, as from the bending of a piece of strong 

 leather is caused by the movement of a thick and solid false mem- 

 brane binding the lungs to the side of the chest. This is often 

 confounded with crepitation. 



Metallic tinkling is only heard when liquid and gas both exist 

 in the pleural sac and is due to the falling of a drop from the 

 shreds of false membrane above into the fluid contents below. 

 The sound is somewhat like the falling of drops in a closed cask 

 half full of water, or it may be fairly exemplified by placing the 

 palm of the left hand flat on the right ear and striking the back 

 of the hand smartly with the middle finger of the right. The 

 sound is chiefl}' heard after the patient has changed its position 

 and especially after rising. The explanation of this is that in the 

 recumbent position the liquid changes its place and bathes parts 

 which in standing are surrounded by gaseous products only. 

 Drops accordingly fall into the liquid for some time with dimin- 

 ishing rapidity until they cease altogether. Other explanations 

 of the sound but which less frequently exist are : the ascent of a 

 bubble through the liquid and its bursting on the surface ; and 

 the sudden recoil of air from one wall of the pleural cavity to the 

 other as the result of movement or sound generated in the deeper 

 seated solid structures. 



A gurgling or splashing sound is equally indicative of the 

 presence of fluid and gas in the pleural sac. It is almost never 

 heard unless after a sudden movement on the part of the patient 

 causing considerable commotion in the contained liquid. Gur- 

 gling sounds transmitted from the abdomen are too often mistaken 

 for this. In small animals with hydro-pneumo-thorax a quick 

 shaking of the patient will develop it. 



Auscultation of the Cough is sometimes valuable, though 

 more difficult and less satisfactory in the lower animals than in 

 man, chiefly because of the extensive movement of the ribs in the 

 former. As conveyed through a healthy lung to the ear applied 



