There is at first a congestion and increased vascularity of the membrane, and a loss of its satiny polish; the synovia is increased in quantity, but becomes thin and serous, and at a later period, mixed with plastic material. If the disease progress, the vascularity and swelling of the membrane increase, and it becomes turgid and distended with blood and effused fluids; a thin, purulent-looking fluid, composed of granular corpuscles, floating in a serous liquid, is poured out, and disintegration, with thinning and erosion of the cartilage, ensues; or granulations are thrown out on the looser portions of the membrane, and, becoming injected with blood-vessels, form fringed membranous expansions, in contact with the ulcerating part of the cartilage. In chronic synovitis, the swelling from the accumulated serous fluid may become so considerable as to constitute a true dropsy of the joints—_hydrarthrosis_. This same accumulation may, however, take place without any evidence of preceding inflammation. _Pulpy Degeneration of the Synovial Membrane_ is peculiar to the articular lining membranes, nothing analogous having been found in the serous sacs. The reflected portions of the synovial membrane are first attacked, and converted into a light-brown, pulpy substance, from a quarter to a half, or even a whole inch in thickness, intersected with white membranous lines and red spots, formed by small injected vessels. The membrane of the cartilages are then invaded, ulceration in the cartilages going on at same time, till the ulcerating surfaces of the bone are exposed. The disease almost always occurs before the middle period of life, frequently can be traced to no cause, but is occasionally the consequence of repeated attacks of inflammation. It generally occurs in the knee, but has been met with in the ankle and in a joint of the finger. A growth of large villous processes, presenting a shaggy appearance, is sometimes observed. “They have sometimes the form of simple threads or flattened shreds, or their free extremities are split into filaments or have a club shape, or resemble melon-seeds hanging singly, or in clusters from each stalk. In many cases, the healthy texture of the articulation is not materially affected.” =Morbid Conditions of Bursæ.= “These small synovial sacs are liable to be affected much in the same way as larger ones. They may be attacked by inflammation more or less acute or quite chronic, resulting from rheumatism, the abuse of mercury, or some other constitutional affection; or excited by violence or long-continued pressure. The effusion which takes place may, in cases of a chronic kind, be a simple synovial or serous fluid; but when the inflammation is more acute, it is either a turbid serum, with flakes of fibrinous matter floating in it, or actual pus.” The walls of an inflamed bursa sometimes become very much thickened by the organization of layers of fibrinous effusion.