If such an area opens spontaneously, or is opened by incision, the contents are seen to be composed of a yellow, rather gelatinous material, quite like the caseous material from a tuberculous abscess. +Treatment.+ In most cases the regular anti-syphilitic treatment is indicated. In cases of periosteal thickening, the results vary with the time at which the treatment is begun. In the early cases, a thorough anti-syphilitic treatment may lead, after a varying length of time, to complete disappearance of the newly formed periosteal bone. On the other hand, if the periosteal process has lasted for a long time and the bone has become densely cortical, although anti-syphilitic treatment may lead to a diminution of the localized pain, the dense bone does not disappear. In cases of combined endosteal and periosteal thickening, the pain usually disappears under anti-syphilitic treatment but the changes in the bone persist. +Osteomalacia+ is an acquired disease which causes marked softening and changes in the bones. The disease begins irregularly and often progresses with or without remissions. The progress is more marked during pregnancy. The first sign is pain in the bones, which is increased by pressure, and this is especially true of pressure over the ribs. There are also muscular cramps and contractures. +Osteitis Deformans.+ (_Paget’s Disease_). This is a chronic disease of the bones and may affect one or more bones of the body. The onset is insidious, and before actual deformity occurs, long indefinite pains in the legs may have existed, with occasional tender points over the bone. The bony changes are first noticed in the bones of the legs and are most marked in the tibia, femur and fibula. As a result of structural changes, these bones become bowed, while their internal trabecular structure is altered. The extent of the affection in the bones of the legs varies a great deal and usually is not symmetric. The lower extremities are bowed outward, and also are usually bent forward, the curves being due to changes in the femur and the lower leg. +Treatment.+ In the absence of any knowledge as to the cause of the disease, the treatment of osteitis deformans must be largely symptomatic. Certain drugs have been recommended; among these are iodide of potash and arsenic. Most such patients are in poor general condition, and effective feeding often gives marked relief of the symptoms from which they are suffering. For severe pain, counterirritants are valuable, especially the actual cautery. Massage is of use in some cases for improving the general condition. +Tumors of Bone.+ All the primary tumors of bone are of the connective tissue group, but various secondary tumors of epithelial origin may occur.