530 PERCUSSION. 



siderable reservation. Allowance must be made for the 

 position of the heart and some of the abdominal viscera in 

 relation to the two sides of the chest, in various domestic 

 animals, before any satisfactory conclusions can be arrived at 

 from their variations in resonance. This will be better illus- 

 trated by considering shortly the degrees of resonance 

 elicited by percussion from the various parts of the thorax in 

 our domestic animals. The sounds, however, vary greatly 

 on the same parts of animals even of the same species. 

 Thus, in the case of a flat or ill-developed chest, the sound is 

 much less marked than in one active and well-developed; this 

 results from the latter containing a larger quantity of air, 

 and having the individual air-sacs better filled. Resonance 

 is always much reduced by a full stomach, or any cause, 

 in short, which prevents the perfect inflation of the lungs. 

 In order to obtain a satisfactory result, the different parts of 

 the lung, and especially the corresponding portions on the 

 two sides, should be examined at the same stage of the 

 respiratory act. 



Horse. Left side. In the superior region the sound is 

 very clear immediately behind the shoulder, especially so 

 over the 12th and 13th ribs, and diminishes gradually from 

 the latter backwards. Behind the 14th rib the abdominal re- 

 sonance is easily produced by forcible striking. In the median 

 region, considerable resonance exists behind the shoulder on 

 the level of the 5th and 6th ribs, it is especially marked 

 from the 7th as far the llth, but behind this gradually 

 diminishes to the last. In the inferior region the resonance 

 is present, though weak, over the 4th rib ; the sound is nearly 

 dull over the 5th, 6th, and 7th, when the heart occupies a 

 notch in the lung; it acquires intensity again over the 8th, 

 behind which it becomes less marked, and is replaced by 

 dulness over the 13th rib. 



