M. Laennec observes, “that the superior lobes of the lungs are the most common seat of tuberculous ulceration; but that they also occur in the centre of the lungs; in their anterior, middle, or lateral parts, or even in their inferior edge, while the superior lobes are uninjured.” In a case in which we suspect pectoriloquism, we must therefore make our investigation sufficiently extensive. Also, in a suspicious case, we are not to form a decision upon a single examination; “because the sputa contained in the excavations may obstruct for a time the communication with the bronchiæ, and thus suspend pectoriloquism for several hours.” M. Laennec further observes, “If, after repeated trials, we cannot discover pectoriloquism, we must infer, either that the tubercles are still immature, or, if softened, that they do not communicate with the bronchiæ; or, lastly, that the disease is not phthisis.” In cases of pleurisy, when there is serous effusion between the layers of the pleuræ, the voice affects the stethoscope so as to produce that peculiar phenomenon of bleating sound, to which the term _œgophonism_, or _caprine pectoriloquism_, is given; from the supposed resemblance to the voice of a goat. M. Laennec considers that “the natural resonance of the voice in the bronchial tubes is rendered more distinct by the compression of the pulmonary tissue, and by its transmission through the medium of a thin layer of fluid.” I have traced, in a case of pleurisy, the daily diminution of this phenomenon, in proportion as the absorption has taken place, and the healthy condition of the pleural membrane has returned. I should add to this concise account, that M. Laennec considers œgophonism to be a favourable sign in pleurisy; because it indicates a moderate degree of effusion. It is not found, “if there have been a rapid and copious effusion, by which the lung becomes suddenly compressed against the mediastinum; nor where a former attack of the disease has firmly attached the posterior parts of the lung to the pleuræ.” Four principal kinds of rale or rattle are enumerated, as discovered by the stethoscope. They are termed, “the humid or crepitous; the mucous or guggling; the dry sonorous, and the dry sibilous or hissing rattle.” Other characteristic varieties might be mentioned. For the physical explanation of these phenomena we must refer to the altered condition of the air cells, the bronchial tubes, or the pleural membrane, occasioned by inflammation and its consequences; or, sometimes by spasm only as regards the bronchiæ. For many details on this part of the subject, the reader is referred to M. Laennec’s Treatise by Forbes.