During six or seven months the limb was observed to increase in length gradually, but very slowly. At the expiration of that time, a contraction took place suddenly, and, in one night, the diseased thigh became shorter than the other by nearly two inches. The patient was then admitted into the hospital, where, after some time, she sunk under her disease. On opening the body the following appearances were presented to Desault, who was then consulting surgeon to the institution. The cartilage of the acetabulum swollen to such a degree as to fill up the whole extent of that cavity, was yellowish and inorganic, somewhat resembling bacon, both in colour and consistence. A soft, spongy, whitish substance projected in the middle of it, the remains no doubt of the round ligament. The head of the os femoris, situated where it is usually found in luxations outward and upward, was surrounded by a cartilage equally tumefied. 5. Here the cause of the displacement of the os femoris was evident. The cartilages becoming tumefied, in consequence of the contusion and violence done to them, had by degrees, filled up the acetabulum, forcing out in the same gradual manner the head of the bone. Hence arose the original lengthening of the limb. But as soon as the head had escaped from the lacerated capsule, the limb was drawn upwards and consequently shortened, by the action of the muscles, and the weight of the body pushing the pelvis downward. CASE II. Some years afterwards, Desault had occasion to witness again the same disease, in the person of a man aged thirty-seven, who put himself under his care, but, being obliged to leave Paris, a short time afterwards, retired into the country, where he died in about six months, enfeebled and consumed by a hectic fever. On opening the body, the surgeon of the place discovering the same phenomenon as in the preceding case, made a preparation of the part, and sent it to Desault, whose pupil he had been. 6. In this case the shortening was not so sudden as in the preceding one. It appeared at first to be coming on, during five days, in an imperceptible manner, when, fatigued with lying in bed, and having on that day drank a little, the patient attempted to walk, supported only by a cane. By evening, a shortening of two inches and a half had taken place, an effect evidently produced by the weight of the body on the diseased thigh. Hence the necessity of confining the patient to a state of perfect rest, of preventing, in particular, standing and walking, and all positions in which the diseased thigh would have to sustain the weight of the body.