Of the twenty-eight guinea pigs treated with sublethal doses of carbonate of lead seven (25 per cent.) showed a peculiar condition to which so far attention does not seem to have been directed. There has developed a hemorrhagic, sero-fibrinous inflammation of the pericardium, of the peritoneum in the upper part of the peritoneal cavity and occasionally also of the pleurae. In the pericardium the lesion commences with a hemorrhagic exudate followed by the formation of fibrinous deposits especially on the parietal layer and ending with organization with marked thickening and occasionally adhesions. In the pleurae one finds as a rule a simple serous exudate without deposits but occasionally heavy deposits of fibrin also. In the peritoneum also the condition commences with fibrinous deposits and eventually leads to marked peritoneal thickening more especially in the upper part of the peritoneal cavity. The capsules of liver and spleen are much thickened and the contraction of the thickened capsule often causes ...