The joints are usually swollen, and the epiphyses of the bones enlarged by the exudation of a reddish serum into the enlarged cancelli and canals, the osseous corpuscles, at the same time, showing a deficiency or entire absence of earthy matter. The periosteum is pulpy and thickened, and more than usually adherent to the bone. If a reparative process have been set up, the deformity may have been greatly diminished, or even entirely removed; or a new deposit of bone taken place, so as to afford a useful limb during life. “This supplementary ossification is found, on vertical section of a long bone, chiefly on the concave side, so that this part of the shaft may present double and treble the thickness of the opposite side. The structure, at the same time, is very dense, and of ivory texture.” In flat bones, as in those of the skull—which is commonly unduly large in rickety subjects—there is a uniform thickening. In some cases the thickening affects the capacity of the foramina. In a peculiar form of disease of the cranium described by Elsasser, the bone is atrophied, soft and porous; numerous openings are found along the lambdoidal suture, and in the body of the bone, with the exception of the occipital protuberance. The perforations are filled up only by the dura mater and pericranium, which are adherent to one another. This disease is commonly met with between the third and sixth months of infant life. =Mollities Ossium, or Osteomalacia=, is regarded by some as a form of atrophy, by others as identical with rachitis, except that it attacks adults instead of children, and by others as an essentially distinct osseous disease. It is of rare occurrence, and consists in perverted nutrition of the skeleton, whereby the earthy phosphates are eliminated from the system by the kidneys, while a deposit of fat takes place in the cartilaginous matrix. As the bones of the trunk are especially liable to be attacked, the individual affected becomes reduced in size by the collapse of the vertebral column. It attacks females more frequently than males, and the former chiefly after they have commenced child-bearing. The disease presents two varieties—the _waxy_, in which the bones, especially those of the pelvis, present a dirty, dark-yellow color, and remain greasy after drying; and the _fragile_, where the bones are of a snowy whiteness, and of a light, transparent, open texture, and so fragile that they give way under the mere pressure of the finger. Under the microscope, we find the corpuscles and their canaliculi empty and transparent, and only faintly visible, and the Haversian canals unnaturally enlarged. Morbid Growths. =Enchondromatous Tumors=, are usually found in connection with some of the short bones, more particularly those of the fingers and toes, though the ribs, vertebræ, sternum, tibia and femur are sometimes attacked.