The form of these vegetations is partly influenced by their mass or size.

Smaller vegetations occasionally exhibit a superficial roughness, only appreciable to the sight and touch on a close investigation, and which is produced by the presence of fine granular or extremely delicate villous structures on the endocardium of the valves.

When these structures are deposited upon one another in a finely granular form, they are more prominently visible on the surface of the valves.

They commonly present a coarsely granular or villous and finally a shaggy appearance, measure several lines in length, and are arranged either in rows of rigid, pointed, unyielding, excrescences, or soft, relaxed, and pendent villi.

They form shaggy appendages, having a thick, club-like, free extremity; or, when of a more considerable size, they form round, oval, or pyriform pedicled excrescences.

Lastly, when of considerable dimensions, they somewhat resemble condylomata, having a cock's comb or mulberry-like appearance, or they are irregularly nodular, and either broad or pedicled.

Partial reference has already been made to the dimensions of these vegetations, which vary from the size of a hemp-seed to that of a hazelnut.

As we have already remarked, these structures may occur in very small or in very large numbers. In the latter case different forms and sizes are usually found associated together; at the same time, they are commonly spread over a considerable extent of surface.

Their color, consistence, and composition vary according to their age, and the quality of the fibrin from which they are formed. We shall, however, revert to this subject in the proper place.

Their principal seat is in the valvular apparatus; they attack the mitral as well as the aortic valves of the left side of the heart, and are generally remarkable for the number and size in which they are exhibited in all the different forms of this affection, to which we have already referred. They are, moreover, observed on the tendons of the papillary muscles - in any part of the inner surface of the heart (the endocardium of which is, in consequence, thickened and rendered opaque, while its surface presents an absence of smoothness), - in and upon the margins of any fissure of the endocardium or of the subjacent tissue - on the margin of a fissure in the valve - on the edge of acute aneurism of the heart - on the torn extremities of a papillary tendon - on the inner wall of chronic aneurism of the heart - and, lastly, even without the heart, on rough, ragged, and uneven spots on the inner surface of the arterial trunks.

They occur especially on the valves in small numbers, in the form of minute granular or villous depositions at the separate segments of the auriculo-ventricular valves, or on the nodules of the semilunar valves, and in their vicinity. They, moreover, in some cases form a granular, villous, or shaggy margin of varying breadth, near the free edge of the valve, which, inclining in a crescent-like form along the semilunar valves, follows the fibrous coat in the parenchyma of the valves. When occurring in great numbers, they occupy a considerable portion of the free margin of the valve, and, assuming every possible form, extend upwards over the whole valve to the endocardium of the auricle, and downwards to the tendons of the papillary muscles.

At other portions of the endocardium they commonly form granular or delicate villous deposits at the margin and in the vicinity of fissures, and most frequently near some exuberant quantity of large villous masses.

It is worthy of remark, that all these forms of vegetations follow the course of the blood-current in every direction. Where they exhibit a broader margin on the auriculo-ventricular valve, this margin forms a projecting angle, from whence it is rapidly deflected. When they form villous or larger masses, they incline at the auriculo-ventricular valve towards the ventricle, and at the semilunar valves towards the direction of the vessel. We must also observe, that they are always situated on the side of the valve which is turned towards the calibre of the implicated opening.

In reference to their color, they are, when newly formed, and at the commencement of their existence, usually of a pale blue or yellowish red color, less frequently dark red, and are either uniformly colored, or speckled and seamed. They gradually become pale, resembling faint yellow, faded, and thoroughly washed fibrin; frequently, however, they do not part with their hsematin, which in its further metamorphoses gradually loses its color, assuming a brownish-red, rusty yeast-like tinge, by which the vegetation is permanently characterized. These structures usually exhibit the consistence of a fibrinous coagulum, varying in their degree of softness or hardness; thus they usually become harder in proportion to the increased paleness of their color, although in some rarer cases they are soft, dissolving like the globular vegetations.

On lifting or tearing off the vegetation, there immediately appears, if it be recent, a loosened, excoriated, and rough portion of the endocardium, which, in structures of older formation, is also raised and swelled up. As they become older, they at the same time become more firmly attached to the endocardium.

The following facts may be noticed in reference to their metamorphoses subsequent to the process from which they originate: a. Vegetations once formed, in most cases, remain stationary for a long time, or even through the whole period of life, more especially when they have acquired any considerable dimensions; but it is certainly undeniable that they may, in the course of time, shrink and diminish, and exhibit an increase of condensation and consistence (excroissances cornées, eartilagineuses, Bouillaud), as we see in other fibrinous coagula.

b. There is no doubt that they diminish in a different manner, and that at times their presence is scarcely perceptible, since they often degenerate into fine, whitish, brush-like fibrinous villi, and in some cases even wholly disappear, without leaving any trace of their existence. The latter is proved by the circumstance (see p. 144) that, while in obsolete cases of endocarditis, the valves exhibit very insignificant or even no traces of vegetations, notwithstanding that they bear the impression of former intense disease, recent endocarditis very commonly presents a large number of these structures, characterized, in many cases, by the size and quantity in which they occur. These vegetations present an analogy with other fibrinous coagula within the vascular system, by being worn out, as it were, superficially, that is to say, they are taken up into the blood in fine particles, and are thus gradually diminished. This remark especially refers to such vegetations or portions of them as are separated from the fibrin of the blood of the heart in the form of coagula, whilst those which have been deposited by exudation remain and shrivel up. (See our subsequent remarks on the origin and nature of these vegetations).