=The Pathology.=--The pathology of guinea-pig scurvy is essentially that of human scurvy. Hemorrhages and separations of the epiphyses or fractures of the long bones dominate the macroscopic picture. The hemorrhages are found rarely in the gums, but are common about the joints, in the muscles of the jaw or in those of the hind legs. They may be subcutaneous and appear as bluish discolorations at various parts of the body, especially if the disorder has resulted in death or if infection has been superadded. On stripping the skin we often note hemorrhages in the intercostal muscles, and beading of the ribs at the site of the costochondral junctions, least marked in the upper and in the floating ribs. This has been frequently described in connection with guinea-pig scurvy; its similarity to the rosary of human rickets has been drawn attention to recently by Jackson and Moore. It should not be regarded as "pseudo-rhachitic," but as typically scorbutic, from a microscopic as well as a macroscopic viewpoint. On closer examination a yellowish-white transverse line may be seen at the epiphyseal junction of the ribs, and frequently some subperiosteal hemorrhage. Beading of this character has been reported by Ingier also in the "snuffles" of hogs and as the result of trauma. A similar enlargement of the chondral junctions of the sternum may be found on examining its posterior surface. _The joints_ of the body always show some changes. The epiphyses are enlarged to a variable degree, resembling the epiphyses typical of human rickets. As in infants, this change is met with most commonly at the wrist joint, involving the ulna and the radius. The knee-joint is likewise often involved, especially the ends of the tibia; the elbow, ankle, and the shoulder may also show an articular swelling of the bones. About these joints hemorrhages in the subcutaneous tissues may be seen, or edema extending along the extremities. Not infrequently a fracture of one of the long bones is found, which may or may not have been diagnosed during life. The common site of fracture is the lower part of the tibia or fibula. Much more frequent than fractures are separations of the epiphyses, which long since have been recognized as typical of infantile scurvy. Even gentle handling in the course of performing the necropsy may occasion a lesion of this kind--of the tibia at the knee, of the radius or ulna at the wrist, or indeed at any of the epiphyseal junctions. The infracted ends occasionally may be seen held insecurely by a delicate band of periosteum. The shafts of the bones are brittle, rarefied, and easily broken. On opening _the chest_, slight hemorrhages may be noted in the pericardium and in the visceral and costal pleuræ. The heart is frequently enlarged, and the pericardial sac contains an excess of serum; the right ventricle, however, is not found disproportionately hypertrophied. Pneumonia is met with very frequently and constitutes a common terminal infection.