AUSCULTATION. 85 



with the exception of the place on the left side which receives the heart's 

 pulsation. We must take care not to confound the slight crepitating 

 noise occasioned by the subcutaneous cellular tissue — which is called the 

 dry crepitous rale — with the murmur. We must also distinguish the 

 sounds of the bowels, which are characterised by their rumbling and 

 travelling about from place to place. 



MoKBiD SOUNDS. — Discase modifies the healthy sound in such a 

 manner that the murmur may become diminished^ extinct^ augmented, 

 attended or superseded by other sounds. 



Diminished murmur. — Accumulated mucus within the large bronchi — 

 as in bronchitis — may temporarily lessen the murmur, though it returns 

 after expectoration. Capillary congestion within the parenchyma, before 

 the onset of inflammation, equally occasions a considerable diminution of 

 the respiratory murmur, speedily succeeded by the crepitous rale, should 

 the inflammation continue. The diminution may be partial or general : 

 rarely the latter. Acute enteritis and peritonitis, and in general all 

 violent abdominal pains, accompanied with a short quick respiration, 

 occasion a notable diminution of the murmur. The same remark applies 

 to all diseases about to end in death. 



Absence of murmur is owing, in certain conditions of the lungs, to 

 the non-penetration of air into the air-cells. This may be the result, 

 1st, of efiusion into the parenchyma; 2dly, of induration; 3dly, of the 

 presence and development of tubercles, or other accidental productions ; 

 4thly, of displacement and compression of the lungs by fluid efiiised into 

 the chest. The loss of sound may be partial or general. It will return 

 on the air-cells becoming permeable again. 



Augmentation of murmur will accrue from accelerated respiration 

 after exercise. Should this happen during rest, it is likely to result 

 from dilatation of the heart or large vessels ; in which case the sound is 

 loud, and is heard throughout the lungs. Should the sound be louder 

 in one lung alone, or in places only of both lungs, it is owing to a morbid 

 state of lung ; it being in the latter case in general referable to non- 

 permeability of certain parts of the organ. In such a case as this, it is 

 probable that the healthy portions of lung in some measure compensate 

 for the diseased parts, in admitting a larger quantity of air. For 

 example, should the left lung become hepatised, the murmur in the right 

 will become augmented ; the same as partial hepatisations will cause an 

 increase in the surrounding healthy parts of the same lobe. In all cases, 

 this augmented sound takes the name of supplementary respiration. 

 Again, the breathing becomes supplementary, and to a remarkable 

 degree, along the superior regions of the ribs, in pleurisy affecting either 

 both sides or one only, followed by effusion, at the time that the lung, 

 still permeable, becomes pressed by the fluid into the upper parts of the 

 chest. 



