This distension of the air cells, is more marked along the edges of the lungs, the vesicles at these parts being probably the least supported. Patches of dilated cells may be found, however, at other parts, which, if superficial, will project beyond the surface of the surrounding healthy portions, and appear like large bladders, from the coalescing of several vesicles. This form of emphysema may be induced by any cause interfering with the ready escape of the air from any portion of the lungs, especially if accompanied with severe cough, as in many forms of bronchial disease, enlargement of the bronchial glands, etc. _Interlobular Emphysema_, consists in an effusion of air into the connective or areolar tissue of the lungs, from a rupture of air cells or smaller bronchial tubes, or from the laceration of the lungs from a broken rib, when the air may accumulate in the pleural cavity, constituting pneumothorax, and may also be accompanied with emphysema of the chest, neck and head, from an escape of the air at the point of injury into the tissues of those parts. This form of emphysema may involve a large part or the whole of the lung, while the vesicular form is generally limited to definite portions. By disturbing the circulation through the lungs, emphysema is liable to induce dilatation of the right side of the heart. From an evolution of gases within the lungs after death, we may have similar appearances to that above described, requiring some care to distinguish between the two. In the latter case, the general indications of decomposition, with the ease with which these distended vesicles may be emptied by pressure, will aid in determining the character of the case. Tubercular Disease of the Lungs. I shall not attempt to present here the various theories that have been promulgated as to the nature and origin of tubercle, contenting myself by giving a description of their anatomical characters, as presented in the several stages of tubercular disease. _Tubercle_, or tubercular matter, may be described as consisting of a yellowish-white substance, opaque, friable and unorganized. It may be deposited in most of the tissues or organs of the body, but its more common seat is the free surfaces of mucous membranes, though often found in connection with the serous. Tubercular deposits in the lungs, are not uniformly distributed through all parts of those organs, being in the large majority of cases confined to the upper and back part of the upper lobes, and in those cases where they are more or less distributed through the whole lung, they will be found more numerous and larger in those parts.