When bone is extensively affected with inflammation, motion is impaired; the muscles being displaced and retarded in their action by the swelling and irregularity of the bone, by effusion of lymph into their tissue and intermuscular spaces, and, perhaps, also, by their partaking, in some measure, of the inflammatory action. Any attempt to move the parts very much aggravates the patient’s suffering. Occasionally inflammation attacks almost all the bones in the body, and causes great constitutional disturbance, by exhausting the powers of life: it sometimes terminates fatally. Bones become inflamed from various causes. However it originates, the action ends, as in the other tissues, in resolution, suppuration, or mortification. The effusion by which the diseased vessels naturally relieve themselves in softer textures cannot here take place so readily, or to such an extent as to prove beneficial: the intensity of the action is with difficulty subdued, and, consequently, resolution is comparatively rare. When it does occur, the parts do not soon regain their natural condition, but often remain considerably swollen and indurated, as is seen in nodes, which continue during the life of the patient, without causing pain or much inconvenience. Suppuration on the surface, or in the centre, and partial or total death of a portion of bone are the most frequent consequences of external injury and incited vascular action; but suppuration in the cancellated texture frequently follows very slight incited action in those of a scrofulous habit. Tubercular matter exists, in all probability, previously, and it leads very often to long continued disease, curable only by operation. The matter may find its way to the surface after long suffering and great constitutional disturbance. Again, it may be confined for months, or even years, the patient suffering from time to time the most excruciating agony. The bone becomes thickened towards the surface by new deposit, as the cavity is increased by ulcerative absorption, and relief is only afforded, a correct diagnosis having been formed, by artificial evacuation of the matter. In many cases small sequestra lie in the cavity; and though the matter escapes naturally, or is evacuated, the patient’s strength becomes worn out, and he perishes, unless the limb is removed. So long as dead portions of bone remain, the discharge cannot cease permanently. Fresh collections are apt to form in the soft parts if the original openings close. It is no easy matter to discover or remove sequestra from deeply seated bones. A section of the femur is represented on the next page, showing a cloaca leading to the cavity of an abscess in the medullary canal. The bone is very dense in consistence, and irregular on its surface. [Illustration]