On such an extensive subject it is unnecessary to enter fully; not that the inquiry is uninteresting, or that a knowledge of the diseases of the internal cavities, and the mode of treating them, is not required of the surgical practitioner before he can enter into practice, with safety to his patients and comfort and satisfaction to himself, but we have a very important class of diseases to bring under review in a limited space, and it is properly the province of others to treat of internal disorders, and to describe the best mode of alleviating or curing them. It is, however, the duty of the surgeon to treat the inflammatory affections of some of the serous membranes, and the consequences of inflammatory action in most of them; and it is therefore highly necessary that he understand the symptoms, progress, and consequences of such actions. The affections of the serous membranes are principally under the management of the physician; but they not unfrequently follow wounds and surgical operations, and the diseases of several of them are purely surgical. Inflammation of a serous membrane is attended with heat and pain, aggravated by motion of the parts and by pressure; the natural secretion is increased in quantity, the process of exhalation being incited, and that of absorption weakened; the serous fluid accumulates. The secretion becomes altered in quality, and assumes a milky appearance; lymph is effused, generally mixed with purulent matter, and floats in the fluid, or adheres to the surface of the membrane, which is rough and flocculent. The adherent lymph becomes organised, being penetrated by numerous bloodvessels; and thus the original membrane is, in many instances, much thickened, chiefly from the addition of new matter, though also from enlargement of its bloodvessels and opening out of the primitive tissues, principally the subserous cellular. When inflamed serous surfaces, which have been altered, both in texture and function, in consequence of inflammatory action, remain for a short time in contact with each other, lymph is effused and penetrated by bloodvessels from each surface; thus the new deposit is organised, and forms a medium of connection. By this process the parts are intimately united to each other, and consolidated into one mass; or are merely approximated, and joined, at one or more points, by portions of lymph, in some cases thin and narrow, in others extensive and of considerable thickness; the adhering bands either extend in a straight direction, from one surface to another, or interlace, forming a sort of network. After adhesions of various kinds have been formed, they are often lengthened and attenuated in consequence of the motion of the parts, as is particularly the case with adhesions between the pleura costalis and pulmonalis. When they have been of considerable duration, they often resemble the original membrane from which they were deposited,