Such specimens as here depicted are common enough in the collections of those who have practised the old round-about operation; in fact, it is only by this painful and tedious interference of nature that a tolerable stump is formed in many of these cases. Death of a small portion will sometimes, though very rarely, follow even a very well performed amputation, if through any mischance the recovery is slow, and wasting discharge takes place with emaciation. It happens sometimes, as when secondary hemorrhage (that is to say, bleeding after the fourth day) has taken place, that the flaps are separated by the coagula, and it may be impossible to bring the parts together and give them due support; then the muscles, wasted and shrunk, may leave the bone a little, but the exfoliation is but very trifling. The inner shell of bone, as may be seen in the above sketch, perishes more extensively than the outer; and this arises probably from inflammation of the medullary membrane, in consequence of exposure, or, perhaps, from its being sometimes injured by the operator or assistants seizing the bone rudely to steady the stump, in order to facilitate the ligature of the vessels. In experiments on animals, the disturbance and injury of the medullary membrane is followed by internal necrosis, thickening of the outer living shell, and effusion betwixt the periosteum and bone. New bone is also furnished from the medullary canal, as is also shown in the sketch. FRAGILITAS OSSIUM Occurs chiefly in old people, whose bones contain an undue proportion of earthy matter, are endowed with little vascularity, and filled with an oleaginous fluid. They contain an undue quantity of phosphate of lime compared to the gelatin; and the liability to fracture is further increased by the interstitial absorption of the outer shell. They are in an atrophied state, and this is often in part attributable to disuse of the limbs. This state of the osseous system very often follows upon an attack of rheumatic fever, and is met with in patients who have laboured under cancerous affections. The bones, when in this condition, often break from the slightest force applied; as from the action of the muscles when the patient turns himself in bed, whilst walking across the room, or when endeavouring to attain the erect posture when seated on a chair. After fracture the process of reunion is extremely slow, and it does not take place at all in patients very old and of worn-out constitution. With a view to prevent the occurrence of fracture when the bones are in this condition, for it is impossible by any treatment to prevent the change in the texture of the bones, the only rational indications seem to be to keep the patient on a generous diet, and to prohibit him from making any great muscular exertion—to avoid, in fact, all circumstances likely to produce a sudden action of any particular set of muscles. OF MOLLITIES OSSIUM, RACHITIS, ETC.