In many cases, the appearance which the various parts of the diseased joint present, are similar to those which have been already described when treating of affections of the joints generally. Frequently, however, the osseous tissue in this situation is much more extensively affected. Often the whole cartilage on the head of the femur is completely removed, exposing the bone in an ulcerated condition; and when the system has long borne up under the disease, the greater portion of the head, neck, and even of the trochanter, is destroyed, the extremity of the bone being completely altered in form, and composed of a loose and spongy structure. A similar disorganisation occurs in the acetabulum; the mucous gland is destroyed, the cartilage is often wholly removed, and the margins of the acetabulum absorbed, a large and flat ulcerated depression merely being left for the reception of the diseased femur; in other instances the margins remain unaffected, whilst the ulceration proceeds in the centre, and the cavity is thereby much deepened. Not unfrequently the ulceration proceeds farther, and an aperture is formed in the acetabulum, so that matter accumulates within the pelvis. The opening is sometimes so large that the femur is protruded through it. When matter has formed in the soft parts round the joint, portions of the bones of the pelvis, in contact with the pus, are ulcerated to a greater or less extent, and sometimes these ulcers are surrounded by deposits of new bony matter. From such changes in the osseous parts of the articulation the limb is shortened, sometimes to a great degree, though no dislocation has occurred. Indeed, dislocation is by no means so frequent a cause of the shortening as is generally believed. If the head of the femur has been dislocated, and if the disease in the joint has afterwards subsided, the acetabulum is found to be much contracted, with its margins smooth and little elevated, and, if the patient survive for a number of years, it will be almost wholly obliterated. But a portion of the dorsum of the ilium, upward and backward, which is the most frequent dislocation in this disease, is gradually absorbed, so as to form a sort of glenoid cavity for the reception of the femur, the extremity of which becomes more solid in texture, and more smooth on its articular surface. The remaining neck of the bone is in the sketch here given turned forwards, and must have given rise to great eversion of the toes. I have seen one other specimen of this form of luxation. The limb is generally, however, inverted; and what remains of the head of the bone consequently points backwards. The consecutive luxation occasionally, also, though rarely, takes place upon the pubis. Whilst a depression is thus formed, new bone is sometimes deposited round its margins, whereby the cavity is increased in depth, so as to resemble somewhat the original acetabulum, the new deposit having become smooth and of a regular form. [Illustration]