D. The difference on percussion is not observed. This does not form such an important class as it did in Div. I., because the early detection of insidious disease can seldom be accomplished except in the clavicular region. With reference to changes in the breath and voice-sounds, when we cannot make out any dif ference on percussion, it is to be remembered (1) that at the upper part of the chest behind, too much importance must not be as signed to them, when they seem to be normal in the clavicular region, because of the distribution of the large tubes towards the back of the lungs: (2) that at the lower part of the chest the voice sound is of comparatively little value, because of the distance from the larynx: but in deep-seated pneumonia this is sometimes the only sign we obtain confirmatory of the evidence of general symptoms: (3) the mere weakening of breath-sound by emphy sema, when increased resonance is not perceived, is of very slight moment, except in so far as it accounts for bronchitis being limited to one side of the chest : it is also to be borne in mind as afford ing an explanation of deficient respiration; because (4) in pleurisy, before dulness can exist, the breathing is suppressed, and the dis tinction between the two depends chiefly on the history, and the presence or absence of pain and fever.
Of the cases mentioned under 1, it is to be remarked that no condition of lung gives such a dull, dead percussion sound, with manifest resistance, aa that which is due to pleuritic effusion ; the multiplying of evidences of its existence is therefore unnecessary, but its amount may be judged of by the bulging, more or less, of the intercostal spaces, the lateral displacement of the heart, the space over which breathing can be heard, and the downward displacement of the abdominal viscera.
The term tegophony is one of the opprobria of auscultation ; and yet it has become so consecrated by use, that 4 is difficult to see how it can be got rid of : the name conveys no idea of the sound, and is so completely associated in the mind with the thought of pleuritic effusion, that it cannot be applied without suggesting a theory of the nature of the disease ; it is therefore quite as objectionable as any other word which more explicitly asserts the condition of the lung (e. g., cavernous). It is quite true that when the sound has been fully learnt, it will be recognized in its perfect form, under no other circum stances ; but the resonance of the voice is most commonly increased when there is dulness on percussion, and often acquires a ringing or even a shaky quality, which closely resembles tegophony, and is constantly mistaken for it. ln using the term it must be limited to those cases only in Which, over a small extent of lung surface, a hollow, squeaking, tremulous voice-sound is heard, which above and below passes into something else.
Sometimes, in consequence of the lung being fastened down to some part of the chest by old adhesion, the breath will be heard unusually low in cases of simple effusion, especially near the spine : this source of fallacy must be borne in mind, and an examination of the lateral region viill give sufficient evidence of the presence of fluid.
The condition of the lung is very different in consolidation and compres sion ; the one being a deposibmithin. the other a pressure from without: in both, the-vesicles may be equally obliterated, and the mass equally solid and heavy ; but in the one there is no loss of size, and all the tubes are patent ; in the other all the minor tubes at least are collapsed as well as the vesicles. This circumstance &UT explains the increased breath-sound as heard in con solidation compared with that heard in compression.
In a case in which there is consolidation of the lower lobe along with effu sion of fluid, the upper lobe must suffer compression to allow space for its presence, because the lower is firm and incompressible: in it the tubes remain open while the vesicles are obliterated ; and hence the diffuse blowing, and the diffuse exaggeration of voice which has been noticed. Superadded sound is very commonly present ; in pleuro-pneumonia it will be heard as the fine, crackling sound called crepitation : in (edema of the lungs with passive effu sion, as s coarser sound, which 'is never wanting : the cedematous condition seems to be one rather opposed to the production of tegophony, which often cannot be heard when there is clear evidence of fluid in the pleura.
Chronic thickening of the pleura may continue for long periods after all acute symptoms have subsided. I have observed dulness from this cause in childhood several years after a single attack of pleurisy. It only becomes of un importance when any form of disease attacks the l itself and then the unusual circumstance of breathing being heard throe i out the whole extent of dulness, at once points to some condition different m ordinary pleuritic effusion. A history of some acute attack at an antecedent period may gene rally be obtained in explanation of the circumstance, and we must judge of the condition of the lung just as if no dulness were present.
When a tumor is deeply seated in the lung, the dulness is difflum, with little sense of resistance, and comes out more distinctly on firm percussion; the breathing is weak but superficial, not otherwise changed except that it is less audible than on the opposite side : a blowing sound will be heard when the tumor presses on one of the larger tubes, and it seems to be conveyed to the ear from a distance, in addition to the weak vesicular breathing beard at the surface ; the distant blowing may also be sometimes detected at the back of the other lung.