Affections of the membranes, ligaments, and bones, often occur in persons of weak constitutions, and proceed very gradually. They have been all classed under the general term of white swelling. They most frequently present themselves without any assignable cause, or are attributed to the slightest injuries. The disease generally commences in the cancellated texture of the bones: these are soft and light, and contain in their cells a quantity of caseous or tubercular matter. The softness is attributable to an interstitial atrophy of the bony tissue, as well as to an alteration in the proportion of its constituents; the animal matter being in excess, with a corresponding deficiency of the phosphate of lime. There is an increased vascularity of the medullary membrane, and the cancellated texture contains thin brownish-looking fluid instead of marrow. In cases of disease which has commenced in the cancellated texture, there is hardly any pain at first, and the progress of the disease is remarkably insidious. When the lower extremity is affected, the child is observed to limp; the limb wastes; it appears to be longer, partly from atrophy of the muscles, partly from relaxation of the ligaments and effusion into the joint. The term white-swelling, which ought to be discarded from surgery, was at one time made to include all the different affections to which joints are liable in weak constitutions—thickening of the parts, with an external colourless swelling—collections of matter about articulations, with or without an external aperture—effusion of fluids into the cavities of joints, or into the bursæ—destruction of cartilage by ulceration, or in consequence of portions becoming dead—absorption, ulceration, caries, or intractable ulceration of the bone adjoining the articulation. Those under twenty years of age are most liable to chronic affections of the joints, and they occur very frequently in children. Great anxiety is often shown by friends of patients to account for chronic disease of a joint, so as to save their whole generation from the imputation of being tainted with scrofula. It is attributed, sometimes correctly enough, to some injury perhaps trifling; to a sprain, or twist, or squeeze from a tight shoe, or to a bruise from falling; and it is no doubt true, that young or old people of the most healthy constitutions, if thrown out of health from one cause, will present all the appearances of scrofula, and become affected with chronic diseases of the mucous membranes, glands, joints, or bones, from very slight existing causes.