Osseous structures are frequently found within and upon the heart in the form of bony concretions. They invariably originate in the fibroid tissue which is produced, as we have already mentioned, by inflammation, and in the deposition of new layers of endocardium. In this manner bony concretions are occasionally developed in the fleshy wall of the heart, and in the tissue of the papillary muscles and of the trabecule, in the form of nodular uneven plates, of nodular bands, or of irregular ramifying osseous masses. In the valves where these formations are of frequent occurrence, they are often in the form of nodular, ramifying bands and rings of different thickness. The whole fibroid mass sometimes ossifies, and may then be seen lying free and uncovered in the cavity of the heart, both in the valves and on the wall of the heart, when the muscular fibres are completely destroyed. Bony concretions in the valves are not unfrequently connected with others in the tissue of the heart, and (as we sometimes remark in diseases of the pericardium) with osseous formations in pericarditic exudations of fibroid texture; or lastly they form a bony mass, branching out in various directions. Smaller cylindrically-shaped concretions are often met with in the thickened tendons of the papillary muscles. In ossification of the valves these cylinders are larger and more connected.

The valves of the left side of the heart, especially the aortic valves, also exhibit osseous formations, which are developed in the morbidly deposited hypertrophied endocardium. In the auriculo-ventricular valves they form plates of inconsiderable size, and in the aortic valves stringlike or nodularly rounded concretions. They are distinguished from the bony formations produced from the fibroid inflammatory callus by their yellow color and their similarity to ossifications of the arteries.

We have never been able fully to satisfy ourselves in reference to this last-named osseous formation upon the endocardium of the wall of the heart.

Fibroid tissue and the bony concretions into which it is developed, when they are the remote consequence of inflammation of the endocardium or the tissue of the heart, are limited, like this process itself, almost exclusively to the left side of the heart. The few cases in which they are observed on the right side of the heart are probably those in which there is ossification of the valves. The occurrence of this osseous formation in the left side is moreover limited to the valves and the ventricle, and never extends, according to our observations, to the left auricle. When bony formations occur in an endocardium which presents a morbid deposit, they are almost exclusively limited to the left side of the heart.