Fibroid tissue very frequently occurs in the form of a fibroid thickening of the endocardium on the inner surface of the heart, as a fibroid thickening of the valves and their tendons, in the heart's walls, and in the tissue of the papillary muscles and the trabeculae, where it is accumulated in different quantities and forms. We have always found that this product was based on some inflammatory process - endocarditis, carditis, or their combination.

1 Oesterr. med. Jahrbucher. Jahrg., 1841. Jahrg.

It appears in the muscular substance of the heart, either in the form of white stripes, of diffused strata of various thickness, or finally of large, roundish nodules, or irregularly branching masses. This substance, moreover, constitutes the greatest portion or the whole of the walls of aneurism of the heart, when of a chronic form.

We have never observed fibroid tissue in the heart under the form of an independent fibrous tumor.