The leg, which, according to the patient’s account, had some time ago been much swelled, did not now appear to be at all so. He was continually in great pain, and had been for some time incapable of getting any sleep. His appetite was bad. He was a good deal emaciated. He had a constant slow fever, which arose about five weeks before his admission into the hospital. He appeared pale and sallow in his complexion. From the time of his being placed under my care to the end of ten days, there was no alteration in the swelling, or in the symptoms attending it. In expectation therefore of affording him that relief, which could by no other means be procured, I judged it adviseable to make an opening into the tumor; which I did by incision into the most prominent and fluctuating part; upon which there immediately gushed out a large stream of thin florid blood, and at this instant discovered to me the true state of that disease; which, till now, could not be ascertained by any peculiar symptom distinguishable by the touch, or perceptible to the eye. Seeing this, I immediately filled up the wound with lint and tow; and then proceeded, in as expeditious a manner as possible, to apply a tight bandage upon the thigh, near to the groin; and, lest this might accidentally break, I applied a second ligature below the first, and proceeded to amputate the limb upon the spot. During the operation the man fainted, but soon recovered from this deliquium; and, without any bad symptoms, gradually recovered his rest, appetite, and strength, and is now in perfect health. Upon a dissection of the thigh and leg, I discovered the following appearances: A great part of the fleshy portions of two of the extensor muscles of the leg, to wit, the _vastus internus_, and _crureus_, were destroyed, with the subjacent _periosteum_. Four of the muscles, whose uses are to bend the leg, and which compose the internal and external hamstrings; to wit, _gracilis_, _semitendinosus_, _semimembranosus_, and _biceps tibiæ_, together with that adductor and flexor muscle of the leg called _sartorius_, were removed at a considerable distance from the thigh-bone on its inferior part, and from the _tibia_ and _fibula_ on their superior parts; by which means a large bed or cavity was formed for containing the extravasation, which consisted partly of a fluid, and partly of a coagulated blood; but by far the greatest part of the coagulum had acquired so firm and fibrous a consistence and appearance, as nearly to resemble brown macerated leather in its colour and texture. The neighbouring muscles appeared livid and lacerated. The _os femoris_ was become carious on its inferior and posterior parts; and, at about an inch distance above the condyle of that bone internally, there arose a considerable _exostosis_. The capsular ligament of the knee-joint was become much thickened, and contained about two ounces of a viscid yellow _synovia_.