In acute inflammation of the synovial membrane, and in cases where the cartilage is ulcerated, the pain is very intense, and the spasms of the limb most distressing. This happens when the surface is ulcerated, and perhaps to no great extent. We know that in the horse an ulcerated hollow in the cartilaginous covering of the navicular bone, not so large as to contain a grain of barley, will cause such lameness and suffering as to render the animal so affected perfectly useless. If he is not destroyed at this stage, as many valuable animals have been, the mischief extends, and terminates in extensive disease of that and the neighbouring bones and articulations. It is different if the disease commence, as it sometimes does, in the human subject, in the cancelli of the bone, and on the attached surface of the cartilage, the free surface remaining some time entire and smooth. When the synovial membrane is primarily affected by chronic disease, the pain is in general trifling, often not complained of, and swelling of the part, from effusion, into the joint or neighbouring bursæ, first attracts attention, after it has existed, perhaps, in a slight degree, for a considerable time. The joint is stiff, and pain is experienced from extensive motion; on this account the patient is disinclined to use it, and it is soon tired by the slightest exertion. The swelling becomes more solid, though still remaining elastic, and the feeling of fluctuation diminishes. Effusion of lymph follows that of serum, the latter having been absorbed; the motion of the joint is still further impeded, and the articulation is distorted; the patient keeps the limb in the most easy position, generally that of partial flexion, in which it becomes almost immovably fixed. The cause of the flexed position, which is almost pathognomonic of knee disease, being preserved, seems to be that the limb is insensibly brought into it in order to take the pressure off the interarticular apparatus, the ligamenta mucosa and alaria,—these swell—the muscles of the hamstrings get contracted from habit, and a difficulty, even after the disease is completely subdued, is often enough experienced in procuring complete extension. The muscles, from disuse, shrink, the adipose substance is absorbed, the shafts of the bones also are diminished in size, get into an atrophied state, as the phrase is, and thus the whole limb is rendered slender and wasted, so as to make the swelling of the diseased articulation still more conspicuous. The bones are softened, and the muscles are of a white colour, as in the limbs of the paralytic or bedridden, and resemble more cellular than muscular tissue. The wasting of the muscles and loss of power often precede the appearance of disease; this is frequently observed in the shoulder-joint, the deltoid shrinking, and almost disappearing, before any disease in the articulation is suspected by the patient. Not unfrequently, also, this wasting