=Endocarditis.= Inflammation of the lining membrane of the heart (_endocardium_) most frequently occurs in connection with an attack of articular rheumatism. It may, however, result from blows or injuries of the chest, and has been induced by violent muscular efforts. It is said also, to be often connected with some vitiated condition of the blood, as in pyæmia or Bright’s disease of the kidneys, and has been noticed also in cases of measles, typhus and puerperal fever. Endocarditis more frequently attacks the left, than the right side of the heart. The anatomical appearances, are a loss of smoothness and transparency of the membrane, with an injected condition of its vessels. Deposits of lymph may be found adhering to the free surface at various points, or to the tendinous cords or valves, giving a roughened, or even warty appearance to all those parts. These may become detached, and swept on with the blood, and finally lodging in some of the arteries of the head or extremities, where they are known as _emboli_, they may become a source of serious trouble. The inflammation may extend to the muscular structure, resulting in softening or the formation of purulent cysts. It is, however, upon those folds of the lining membrane constituting the valves, and particularly upon the left side of the heart, that the effects of endocardial inflammations are especially manifested. In this way originates most of the so-called 2. Valvular Affections of the Heart. One of the most common of the results of inflammation extending to the valves, is =Thickening.= This may depend either upon a deposit of lymph beneath or between the layers of membrane constituting the valves, thus rendering them thick and inflexible while the surface is left smooth, or, at the same time, a deposit upon the exterior may be found, rendering them rough and even warty in appearance, and so stiffened and irregular upon their borders as to greatly interfere with the performance of their functions, and thus permitting _regurgitation_ to take place at the imperfectly closed opening.[8] The tendinous cords, at the same time, may be found thickened, hardened, and contracted, or even ruptured, while the auriculo-ventricular openings may also be found greatly contracted from the thickening of the base of the valves and the fibrous tissues forming the borders of the openings. In one case the contraction on the left side of the heart was so great as scarcely to admit the little finger, while the thumb should readily pass that opening. The semilunar valves of the aorta are liable to the same changes, their thickened condition preventing their folding back completely into the sinuses of the artery during the systolic action of the heart, or of completely closing the vessel upon pressure from above.