Along with ulceration of the cartilage, a portion of it may become dead, or either state may occur separately; and in many cases, the substance of the bone also becomes affected, of which two classes of cases may occur, viz., great inflammation on the articular surface of the bone, with separation of the cartilage by the ulcerative process in this situation; and inflammation of the medullary web, leading to atrophy of the cancelli, collections of pus therein, or even death of a portion of the spongy texture of the bone, as will be more particularly treated of in the chapter on diseases of the osseous tissue. These changes often compose the primary disease, and to them the affections of the synovial membrane and other parts succeed. Such occurrences are attended with alarming disturbance of the constitution, with fever, and even with the most threatening and dangerous symptoms, such as delirium and coma. If the patient survive, and the matter be evacuated from the joints by openings into its cavity, hectic fever is almost certain to supervene. An opinion has been broached lately by Mr. Key, that the ulceration of cartilage was consequent upon the increased vascularity and thickening of the synovial membrane, that the cartilage, in fact, was removed by the action of the vessels ramifying in the membrane, and the prolongations or fringes from it in its diseased condition. Occasionally these fringes correspond, in a remarkable manner, to the breach of surface in the cartilage; but again, ulceration is frequently met with far removed from the membrane. It is also seen, in cases where an opportunity is afforded of making the examination in the earlier stage of disease, that ulceration exists to some extent whilst the synovial membrane is unaffected. And certain cases, in which the cartilage is affected with hypertrophy, and the common form of atrophy of this part in old people, are altogether adverse to Mr. Key’s views. When ulceration takes place at a point removed from the attachments of the synovial membrane, it appears to proceed more frequently from the attached than from the free surface of the cartilage; then the adventitious membrane occupying the rugged spaces, and which under the microscope appears highly vascular, is connected apparently with the medullary web.