The Coagula In The Heart may be classed in the following order in reference to their form. Many have only recently been recognized and duly characterized as fibrinous concretions, and these have received designations corresponding to their forms.

a. Clotty, roundish, membranous, ramifying coagula, when occurring in the cavities of the heart, commonly receive the designation of polypi or polypous coagula. These are variously sized clots, presenting differences in the number and length of the ramifying appendices by which their rounded forms are modified. They consist of a dark or blackish-red clot, from which fibrin is separated at some portions of the periphery, but seldom from the interior; or they consist, for the most part, of fibrin which has absorbed a certain quantity of cruor and serum, and appears colored with various tinges of red, or, when free from these, it exhibits a pale and somewhat dense coagulation. These concretions are especially common in the right side of the heart, where they are found in large quantities, generally associated with a loose coagulum and fluid blood, and exhibiting coagula which have been formed during the last moments of life and after death. This form of coagulum does, however, undoubtedly occur at various periods before death. Without entering into a description of these coagula, the limits of which it is difficult to separate, from those of the first-named variety, we would merely remark that the following conditions favor their development during life:

1. When they are situated in the left half of the heart, especially when extending into the aorta and its branches.

2. When their ramifications extend into the ventricles, and their branches are entwined among the trabeculae and the tendons of the papillary muscles.

3. When they exhibit the impression of the contiguous surface of the heart, as is especially manifested in the auricular appendage (the auricle proper).

4. When they adhere or coalesce with the inner surface of the heart - the endocardium.

5. When they consist of pure fibrin, and are at the same time tough and tenacious.

6. When they exhibit a dirty yellowish and greenish color, and are, moreover, opaque.

7. When they present small purulent foci or tuberculous concretions.

8. When any one of the associated diseases of the blood is developed. These coagula cannot in themselves be regarded as symptoms of endocarditis where other essential evidences of the presence of this disease are wanting; and even where the latter are present, they cannot be considered as affording any direct proof of the existence of the endocar-ditic process, but simply of a pre-existing and spontaneous disease of the blood, depending, probably, on the absorption of endocarditic products.

It is incontestible, that these coagula not only adhere to the endocardium, as has been observed, but that they are also capable of entering into an organic or textural connection with the lining membrane of the heart, and thus vegetate independently and without the aid of a vascular system, as they are directly surrounded by the liquor sanguinis. On submitting the observations hitherto made on this subject to the severest criticism, we meet, amid a mass of erroneous and hasty conclusions, with some few cases which unquestionably belong to this class of coagula. These tumors are of various size; of a roundish, oval, cylindrical form, which appear attached to a broad or narrow base, as by a pedicle; they are of a sponge-like, or elastic and tough, consistence; they generally consist of a fibroid structure, but in some cases exhibit a soft texture, composed of membranes, covered with elementary granules and cellular nuclei, of delicate fibrilli, and of thick and even tubular fibres and amorphous coagula. Their color is red, yellowish-red, or white. When they are gradually receiving one or more coverings of newly-formed endocardium, which extends from them to the inner surface of the heart, they present the appearance of having been developed below the original endocardium, or, at all events, in the innermost layers of the muscular substance of the heart. Osseous and cretaceous concretions may be successively developed in them; and the free stony concretions which former observers have recorded as occurring in the cavities of the heart, were, doubtless, nothing more than loosened, liberated, fibrinous coagula, which have become ossified or cretified. We have never hitherto been able to detect vessels in them. (See Faber, Thomson, Vernois).

It is probable, that these coagula are somewhat diminished by a process of solution upon their surface, before they acquire any decided texture and are covered by layers of endocardium, and that they thus lose their original form, which is probably an irregular one, and become round. Such a supposition seems to derive support from analogy with the disappearance of vegetation on the valves of the heart, the gradual rounding of the globular vegetations, and the diminution and disappearance of the plug in an artery after the application of a ligature.