42 The Lung Plague of Cattle. 



The ear applied over the diseased portions detects in 

 some cases a diminution of the natural soft breathing 

 murmur, or it may be a fine crepitation which has been 

 likened to the noise produced by rubbing a tuft of hair 

 between finger and thumb close to the ear. Where this 

 exists it is usually only at the margin of the diseased 

 area, while in the centre the natural soft murmur is en- 

 tirely lost. In other cases a loud blowing sound is heard 

 over the diseased lung, which though itself impervious to 

 air and producing no resj)iratory murmur is in its firm, 

 solid condition a better conductor of sound and conveys 

 to the ear the noise produced in the larger air tubes. 



Percussion is effected by a series of taps of varying 

 force delivered with the tips of the fingers of the right 

 hand on the back of the middle finger of the left firmly 

 pressed on the side of the chest. Over aU parts of the 

 healthy lung this draws out a clear resonance, but over 

 the diseased portions the sound elicited is dull as if the 

 percussion were made over the solid muscles of the neck 

 or thigh. All gradations are met with as the lung is 

 more or less consolidated, and conclusions are to be drawn 

 accordingly. 



In other cases we hear on auscultation the loud, harsh, 

 rasping sound of bronchitis with dry, thickened and rigid 

 membranes of the air tubes, or the soft, coarse, mucous 

 rattle of the same disease when there is abundant liquid 

 exudation and the bursting of bubbles in the air passages. 

 In others there is a low, soft, rubbing sound usually in 

 jerks when the chest is being filled with or emptied of air. 

 This is the friction between the dry, inflamed, membrane 

 covering the lungs and that covering the side of the chest, 

 and is heard at an early stage of the disease, but neither 

 at its earliest nor its latest stage. Later there may be dull- 

 ness on percussion up to a given level on one or both 

 sides of the chest, implying accumulations of liquid in 

 the cavity. Or there is a superficial dullness on percus- 



