In mortification of an extremity, in consequence of injury, removal of the part by incision in the sound substance was formerly as much dreaded as in chronic cases before the separation had commenced; but such fears have now subsided, and the practice of delay has been in a great measure relinquished,—amputation being performed in the sound part, at a considerable distance from the mortified or even gangrenous tissues, and during the progress of the disease, occasionally with a favourable result. If the surgeon defer the operation until a line of separation have begun to form, he will soon discover the danger of his delay; the constitution will, in the majority of cases, rapidly sink under the malady before the progress of the disease is in any measure checked, or any attempt is made to throw off the mortified parts. Two cases which lately occurred in my hospital practice, are here introduced from the “_Lancet_,” to show how different the progress is, and how opposite the practice ought to be. Both the patients made excellent and rapid recoveries. “Sarah Arnold, æt. 75, was admitted on the 26th of January. She has been a person of great mental and bodily activity, and has enjoyed excellent health from her infancy, until her present illness, although necessarily exposed, from the nature of her occupation, a gatherer and hawker of watercresses, to all varieties of weather. About six weeks ago, without being more than usually exposed to cold, she was seized with severe rigors. Two days afterwards she began to complain of slight pain, with clinching of the fingers, which at the same time became discoloured at the tips, and were partially deprived of sensation. This at first did not give rise to much uneasiness, and no treatment was employed; and it was not until a week after the commencement of the disease, when the discoloration had passed the wrist, and the hand had become dry and shrivelled, and motion and sensation in it were completely lost, that a medical man was called in. Both internal and local remedies were then employed, but without in the least retarding the progress of the disease, which in about a fortnight from her seizure had extended a little way above the middle of the humerus, beyond which it did not pass. At present there is a well-marked line of separation between the living and the gangrenous parts, but there are two livid spots beyond it, on the outer side of the arm; on the inner side, where the disease has extended a little higher up than the outer, suppuration has already commenced. The integuments in the immediate neighbourhood of the diseased parts are slightly reddened and tumefied, and it is there only that she complains of some slight pain. The hand and wrist are dry and shrivelled, but above this the parts are soft and flaccid. Below the line of demarcation, the extremity is of a dark colour, resembling the skin of a negro, and completely deprived of the