Hemorrhage occurs in the bone as elsewhere; it is almost never lacking. It appears either as large hemorrhages in the spongiosa, especially where the normal marrow joins either the Geruestmark or the Truemmerfeld, or merely as scattered cells, possibly the result of diapedesis. The blood-vessels in these areas are narrow and extremely thin-walled. The most typical site of hemorrhage is beneath the periosteum, a lesion widely known on account of its clinical significance (Fig. 16). Here the blood may extend for a considerable distance along the shaft, but rarely beyond the epiphyseal line. The clot forms readily, demonstrating that the nature of the hemorrhage is not a defect in coagulation, and in its midst may be seen fibrin, pigment, granulation tissue, and more or less firm connective tissue--constituting the callus. The inner surface of the periosteum is frequently lined with newly-formed bone and with a more or less dense deposition of lime salts, which becomes heavier in the course of the healing process, and is readily observed in radiographs. This periostitis ossificans may result in the clot being surrounded by a perfect shell of bone, with bony columns penetrating the deeper layers. As the result of the lack of bone formation and the consequent weakening of the corticalis and the spongiosa, frequently a separation of the diaphysis from the epiphysis results. This lesion should not be regarded as a true separation, for, as Barlow pointed out, the line of cleavage is not at the junction, but below it, involving the uppermost region of the diaphysis. It is therefore correct to speak of a fracture or infraction. This lesion is generally accompanied by a deformity of the surface contour of the junction, due to a displacement of the cartilage, as a result of which "angular beading" of the rib is brought about. In some instances the cartilage is "telescoped" into the crushed end of the bone. To a varying extent fibrin covers the end of the fractured bone; the angles adjacent to the periosteum contain blood which becomes organized into dense connective tissue, thus serving as a splint for the fractured parts. In the course of healing a large number of foreign body giant-cells appear, blood-vessels sprout from the periosteum as well as the bony surface, and the necrosed tissue gives place to an active formation of callus, which generally leads to complete regeneration and restitution. It is remarkable how quickly and perfectly an epiphysis may become reunited to its shaft (Figs. 6 and 7). Sometimes, however, this takes place with resulting deformity, as in the development of coxa vara of the femur. [Illustration: FIG. 6.--Posterior-anterior view of shoulder of infant (R. S.) 17 months old. Severe scurvy. Subperiosteal hemorrhage of humerus, and separation of upper epiphysis.] [Illustration: FIG. 7.--Anterior-posterior view of same shoulder (see fig. 6) 22 months later. Complete restitution of epiphysis without deformity of humerus.]