Aziscidtation. 169 



MORBID CHEST vSOUNDvS. 



The close study of the healthy chest sounds upon the living 

 animal is an essential prerequisite to the appreciation of the 

 morbid. The abnormal noises are so varied, merge into each 

 other by such imperceptible degrees, and so coexist and complicate 

 each other that they often prove extremely puzzling to the un- 

 practised ear. It is no more necessary that the musician should 

 educate his ear to appreciate the most delicate gradations of 

 musical notes, than that the auscultator should educate his in the 

 sounds of the healthy and diseased chest. Written instructions 

 are of about equal value in the two cases, they prove auxiliaries 

 in the acquisition of knowledge but they can never supersede the 

 practical study of the chest. A mere theoretical knowledge is too 

 often useless in the presence of the patient. 



The abnormal chest sounds are either modifications of those 

 existing in health, or superadded sounds which have no counter- 

 part in the healthy chest. 



Modifications of healthy sounds. The vesicular or respiratory 

 murmur may be increased or diminished in force or it may be 

 entirely absent. 



Increase of the respiratory murmur, is merely an increase 

 in force without any modification in character and resembles 

 juvenile respiration. If increased equally over the entire chest it 

 is general, if only in a part it is partial. General increase of 

 the vesicular murmur is heard after an animal has been sub- 

 mitted to moderate exertion for ten or fifteen minutes. In ani- 

 mals at rest it is heard in active fevers and in the symptomatic 

 fever which attends acute inflammations. 



Partial increase as for example in one lung only, or in cir- 

 cumscribed parts of both lungs, and especially along their superior 

 borders, is indicative of disease of the lungs or the pleurae. It 

 testifies to the impermeability to air of some other portion of lung, 

 from congestion, splenisation , hepatisation, plugging of a bron- 

 chial tube with tenacious mucous, tubercular deposits, tumors, 

 emphysema, or hydrothorax. (See under these names.) The 

 healthy portion of lung in such cases takes on the function of the 

 whole, and the loud breathing is called supplementary. 



Diminution of the respiratory murmur, like its increase, 



