PERCUSSION.-At the time of onset the percussion-note remains clear. As en gorgement progresses, however, the note becomes higher in pitch and frequently possesses a tympanitic quality. With in crease in the exudation and consequent driving out of the air from the air-vesi cles and bronchioles a gradually-increas ing degree of dullness supervenes. This dullness, however, even with the most massive consolidation, is never complete, for the reason that the involved area is never totally lacking in air, which con tinues to pass in and out of the bron chial tubes ramifying throughout the in volved area. Associated with dullness is a sensation of increased resistance to the finger. Over that portion of the lung im mediately above the consolidated area percussion is apt to yield a note of tym panitic quality resembling the so-called Skodaic resonance. The unaffected por tion of the lung and the lung upon the opposite side give hyperresonance upon percussion, owing to the increased func tion which the limitation of air-space makes necessary for these portions to perform.
New sign which the writer has ob served in pneumonia, and one that is nearly always constant. This is a lack of expansion of the subclavicular region of the affected side. This sign, which
has been watched for in all affections of the respiratory tract, has been encoun tered only in pneturionia. In pleurisy and pneumothorax lack of expansion may be noted on the affected side, but it embraces the whole side, and is in direct connection with the seat of the evolu tion. It may be confined to the base or, if the effusion is extensive, may involve the whole side. In pneumonia, on the contrary, the lack of expansion is con fined to the subclavicular region, even— and especially when—the pneumonia af fects the base. It is an early sign which is observable from the first day, and lasts often through the whole course of the disease. Weill (Revue Mans. des Mal. de l'Enfance. Oct., 1901).
With the beginning of resolution and the consequent resorption of the exudate, dullness progressively diminishes as the air again enters the affected area. A re turn to the tympanitic quality of per cussion-note takes place, however, before the resonance assumes its normal quality. Lesions of limited extent are not always susceptible of recognition by percussion. This is particularly the case in central pneumonia, in which the hepatized por tion of the lung is surrounded by unin volved structure.