Death of bone, or NECROSIS, is an effect of violent inflammation, particularly of the medullary web, or external injury; a termination of inflammatory action in bone corresponding to sphacelation in the softer tissues. It has been observed, that the bones are not extensively supplied with bloodvessels, and that their natural powers are inferior to those of the softer parts; and from this circumstance the frequency of necrosis can be readily accounted for. The short bones and the heads of the long bones, are more vascular than the flattened bones and the shafts of the long ones. Hence necrosis most frequently occurs in the latter. Necrosis, fortunately, seldom occurs in the heads of the long bones, or penetrates the separation betwixt the cancelli of the shaft and the epiphysis. Bits of dead bone in the articular ends, however, very often lead to disease in the joint. There are in my private collection a few specimens of necrosis, in which matter found its way into the neighbouring joint, leading to disease of the tissues composing it, and rendering amputation necessary for the preservation of the patient’s existence. External injury may produce this disease by causing a violent increase of action, or it may be so severe as at once to deprive part of the bone of its vitality. Destruction of the periosteum, and of the vessels which enter the surface of the bone, frequently gives rise to superficial necrosis or exfoliation. Such a result, however, does not always follow; for we not unfrequently find, when the periosteum has been forcibly torn off, to a considerable extent, by external injury, that the part still retains its vitality. When, however, the bone has been at the same time contused, it is extremely probable that external necrosis may occur. Again, when the periosteum has been removed in the most careful manner possible, exfoliation occasionally takes place. If the exposed bone remain of a brownish hue, it will generally retain its vigour; if, on the other hand, the colour is white, it will most probably be cast off. Necrosis may come on at various periods of life, but is most commonly met with in young subjects, in whom the inflammatory action is allowed to make progress before it is noticed or attended to. It may affect the external or the internal part of a bone, or nearly its whole thickness. The whole of a bone seldom or ever dies in consequence of increased action, and it is not often that the entire thickness of any part of it is found to be necrosed. If the entire thickness dies to a great extent, there is no reproduction; the epiphyses approximate, and the limb, if there is only a single bone, must be lost. A large portion of a bone, or numerous small irregular portions, may die; but still a part of the original shaft remains, and by its vessels reproduction is accomplished. The articulating extremity is very rarely destroyed by this disease. Many writers have talked of death of a bone throughout