Percussion. i6i 



behind the shoulder as far as the seventh rib, from which it 

 diminishes to the second last (thirteenth). The sound is less 

 clear in the upper and lower thirds. On the fifth intercostal 

 space below, and on the left side the sound is dull owing to the 

 exposure of the heart through a slight notch in the lung. 



Dog. Percussion is very satisfactory in this animal because of 

 the amplitude of the chest, the thinness of its walls and the 

 small bulk of the abdominal organs. In the upper and middle 

 thirds on both sides alike the sound is clear and full as far back 

 as the seventh rib, whence it decreases to the last. In the lower 

 third a distinct but moderate sound marks the first eight ribs and 

 is equally clear on the right and left sides. The thinness of the 

 lung in its posterior part demands that percussion be effected by 

 the middle finger only, without any movement of the hand. 

 Unless the dog is very fat, good results may be obtained by per- 

 cussion over the first and second ribs, the shoulder blade and 

 breastbone. 



Birds. In these and especially in the webfooted (ducks, 

 geese,) the sternum is so thickly covered by flesh that no result 

 can there be obtained. Beneath the wings, however, and upon 

 the back percussion through the medium of a small coin as a 

 pleximeter and with the middle finger alone, is valuable. Be' 

 neath the wing a clear sound may be drawn out over neaily all 

 the ribs and on the back over a less extent (two and a half to four 

 inches, according to size). 



PERCUSSION IN DISBASE. 



Increase of resonance without any perceptible modification in 

 character is usually partial and depends on the increased disten- 

 sion of the air cells of one lung, or part of a lung, to make up 

 for the loss of a part or a whole lung through hepatization or 

 pressure by false membrane or from water in the chest. If a part 

 of a lung is solid and impervious it gives a dull, dead sound, con- 

 trasting strongly with the increased clearness of the remain- 

 der. So with water in the chest, the clearness of the upper 

 parts contrasts unmistakably with the dullness of the lower. By 

 watching the advance or retirement of these symptoms the solidi- 

 fication of a lung and its process of clearing up, and the effusion 

 II 



