EMPHYSEMA OF THE LUNG. 127 



lungs be increased, no very active vibrations, capable of producing any 

 very loud or full resonance, can take place. Neither does the sound 

 jpon percussion become tympanitic, unless there be complications 

 through which the pulmonary tissue entirely loses its elasticity. The 

 tympanitic ring is a result of regular vibrations. If we make percussion 

 upon a bladder, the walls of which are tightly stretched by inflation, the 

 sound is not tympanitic, for the compression of the air, which is aug- 

 mented or diminished every moment by the vibrations of the walls, pre- 

 vents the occurrence of regular vibrations. It is precisely the same in 

 a lung, which has become but a cluster of inflated cysts. The tension 

 of the alveolar walls generally remains sufficient, even in very intense 

 emphysematous disease of the lungs, to prevent the occurrence of reg- 

 ular vibrations. The only characteristic symptom of the disease, fur- 

 nished by percussion, is abnormal extent of the full, clear sound of the 

 lungs, as this proves that the diaphragm is depressed, which, as we have 

 seen, is a necessary consequence of emphysema. While under normal 

 conditions, the percussion-ring, corresponding to the lower limit of the 

 right lung, reaches to the sixth rib at the right mammillary line, and 

 passes over at this point into the dull percussive-sound of the liver, 

 which here lies against the wall of the chest. In severe emphysema, 

 the right lung pushes back the border of the liver considerably ; and 

 we sometimes hear clear percussion-sound almost as far down as the 

 lower edge of the arch of the ribs. Upon the left, the dulness pro- 

 duced upon percussion over the heart commences normally at the level 

 of the fourth costal cartilage. In well-marked emphysema of the left 

 lung it spreads downward, often to the sixth costal cartilage, and in 

 the most extreme cases the heart is so completely covered by the lung 

 that the cardiac dulness has disappeared. 



In auscultation, we must discriminate between the phenomena proper 

 to the emphysema and those which are to be placed to the account of 

 the accompanying bronchial catarrh. As a rule, it is said that the 

 vesicular breathing is feeble or inaudible, in striking contrast to the in- 

 tense percussive resonance. This assertion, however, is only so far cor- 

 rect in that, as a rule, besides the emphysema, there is usually a catarrh 

 of the minuter bronchi. At the points where these complications coex 

 ist, we usually, indeed, hear nothing but rhonchi and fine moist rdles, 

 or, at the utmost, very feeble vesicular breathing. At points, however, 

 where there is no catarrh, where the air passes freely from the bronchi 

 into the dilated cells, the respiratory murmur is generally remarkably 

 loud and hissing. It is very commonly found that we can only hear 

 rhonchi and rdles in the lower lobes of the lungs ; and in a manner strik- 

 ,ngly in contrast with this, particularly at the anterior wall of the chesi 

 in the neighborhood of the sternum, the respiration is loud and hissing. 



