I do not think that wrenches of the knee-joint in the act of falling can be suggested as an explanation of the frequency of effusions into that articulation, since the fractures of the femur were not always received while the erect position was maintained, and effusion was most marked when the diaphysis was the part affected, the latter point illustrating the greater resistance offered by compact bone. Again, when fracture had taken place, the solution of continuity rendered the directly injured point the most mobile, and tended to prevent lateral strain from falling on the joints. Effusion into the knee or ankle, or sometimes both joints, was common in fractures of the shaft of the tibia. In the articulations of the upper extremity the condition was also common, but somewhat less marked than in the lower limb. Effusions into the shoulder or elbow occurred. In the former these were less striking; again, perhaps, as a result of the difficulty of detecting small effusions in this situation. The elbow was to a certain extent protected by the possession of a degree of fixity somewhat resembling that already mentioned in the case of the hip-joint, although here depending on the conformation of the bones alone. I think this explained the absence of free effusion in many cases of fracture of the humeral shaft, but when the latter affected the lower third effusion into the elbow was usually abundant. The lighter weight and greater mobility of the upper extremity as a whole, as decreasing the resistance to the bullet, were also probably an element in the fact that these effusions were less severe than those in the joints of the lower limb. The nature of the effusions was apparently simple, since they were rapidly reabsorbed, and little thickening of the synovial membrane remained to suggest either a marked degree of inflammation, or the deposition of blood-clot on the inner aspect of the same. The only treatment indicated was a short period of rest, accompanied in the early stages by pressure and slight fixation, followed later by massage and movement if necessary. Before dismissing this subject, I should like to particularly emphasise the fact, that in the cases described there was no reason to suspect the extension of fissures from the point of fracture in the shafts into the articular ends of the bones. This was as far as possible excluded by clinical examination, and in the cases where wounds of the soft parts only were present, the rapid return of the patients to active duty, with absence of remaining joint trouble, negatived the possibility of such fractures.