These two species, comprising an acute and chronic form, both of which depend on inflammation, embrace the numerous observations we ourselves have made, and will very probably, on an unbiassed inquiry, be found to include all cases on record.

That inflammation is the original controlling process in this affection is proved not only by the history of inflammation of the muscular tissue generally, and by that of the muscular substance of the heart in particular, but receives additional confirmation from the concurrence of the aneurism with endocarditis and.its products, both as to their position and situation, even beyond the limits of the aneurism, generally even as far as the valves, - from the almost universal and simultaneous occurrence of the products of pericarditis, - from the nearly exclusive occurrence of aneurisms in those portions of the heart, which are in like manner the exclusive seat of carditis and endocarditis, viz., the left ventricle, - and from the residua of the secondary metastatic processes in the capillary system, which are frequently of simultaneous date with the endocarditis.

We see no grounds for concurring in the opinion of many observers who regard the alteration of texture of the endocardium and the substance of the heart on which the second form of aneurism depends as a peculiar or unintelligible alteration.

The question here arises, whether an abscess of the heart (cardite ulcerative of Bouillaud,) after opening into one of the cavities, can give rise to the formation of an aneurism. We are of opinion that aneurism of the heart does undoubtedly supervene, but the question is whether such an aneurism is of a persistent character. We have ourselves observed no case corroborative of such a view, and we doubt whether the pyaemia induced by the opening of the abscess could lead to the consolidation of its walls; that is to say, could heal the abscess by converting it into an aneurism. (Compare pp. 151, 152, on abscess of the heart, and the observations referring to the first form of aneurism of the heart).

Moreover, we cannot suppose the so-called atheromatous process - as it occurs in the arteries - to be the primary condition giving rise to aneurism of the heart. We have already remarked, under the head of hypertrophy of the endocardium, that the newly-deposited layers of endocardium upon the wall of the heart have never, in any case that we have observed, been the seat of any but the earliest stages of that metamorphosis which terminates in atheromatous disintegration, while it is only in some instances that it is observed in a more advanced form in the valves. It is, however, worthy of remark, that we have certainly seen this atheromatous disintegration affect some portions of the depositions lining the inner wall of the aneurism, although in a form which proved that it could not, as a primary disease, have given rise to the formation of the aneurism, but must apparently have been subsequently developed in the already existing aneurism.

Aneurism of the heart occurs almost exclusively in the left side, and is incomparably more frequent in the left ventricle. There is only one undoubted case on record of this form of aneurism of the left auricle, - namely, that of Chassaignac, to which, however, we must add a preparation in our pathological museum of an aneurism of the acute form in the auricular septum. Hence these formations chiefly occur in the arterial half of the heart, which is known to be the almost exclusive seat of endocarditis and carditis. Like the above-named processes, aneurism rarely affects the right side of the heart; and the few cases on record of aneurism of the right ventricle, and those described as situated in the right auricle, prove (like those affecting the left auricle) not to be, strictly speaking, true aneurisms of the heart. These cases usually consist in a general dilatation of the auricle whose walls have been transformed by inflammation into a fibroid, callous, and even ossifying tissue of considerable thickness, and which itself adheres to the pericardium, having its cavity more or less completely filled up with fibrinous coagula.

In the left ventricle the apex is the ordinary seat of aneurism, and here it also attains its greatest size. It is less frequently observed towards the base of the ventricle, and is of very rare occurrence at the septum, which, however, is commonly more or less implicated in those cases where the apex is the main seat of the disease.

It is only in rare instances that we meet with more than one aneurism, and where two or even three exist simultaneously, they are generally in close proximity to one another, and not unfrequently present the appearance of one single aneurism, which has been more or less perfectly separated into two cavities by the marginal elevation of its walls.

That portion of the heart which is affected by aneurism is found, in almost all cases, to be also the seat of an active dilatation, occasioned by the cardo-endocarditic process and its sequelae, by the aneurism itself, and simultaneous valvular affections.

The spontaneous rupture of an aneurism of the heart may be mentioned as an extremely rare termination of the disease. It may open into the cavity of the pericardium, into the pleura, or into the arterial trunk of the opposite cavity of the heart. Such an opening may occur in a chronic form of the disease as the final result of the increasing attenuation of the walls of the aneurismal sac in consequence of its own enlargement, as in a case we have observed where an aneurism in the ventricular septum, and near the apex of the heart, opened into the cavity of the right ventricle (the varicose aneurism of Thurnam). Acute aneurism of the heart more frequently terminates in laceration, which, in most cases, is very probably induced by the same cause which gave rise to the aneurism itself, namely, inflammation and inflammatory loosening of the tissue, and suppuration in the muscular substance of the heart. - In the case of a boy aged nine years, who presented extensive dilatation and hypertrophy of the left ventricle, and thickening of the endocardium at the septum, we observed immediately below the aortic valves, at the uppermost part of the septum, a laceration about the size of a pea, which led to a sac as large as a nut in the auricular septum, that had been formed by the upheaval of the muscular substance, and after penetrating into the right auricle, opened into its posterior side through an aperture about as large as a hemp-seed.

Most of the cases of aneurism of the heart have been observed in persons of mature age and of more advanced life. When, however, we bear in mind that by far the greater number of cases on record belong to the chronic form of aneurism, we are led to conclude that the disease of the tissue, which is the precursor of the aneurism, must have originated many years before the fatal termination of the disease, and therefore in an earlier period of life, the more so from the circumstance that an appreciable number of cases occur before the age of thirty, while we have observed the acute form in early childhood.

C. Metastasis In The Muscular Substance Of The Heart

Metastatic, purulent, and ichorous abscesses in the muscular substance of the heart may be reckoned among the ordinary conditions giving rise to metastasis, more especially when occurring in consequence of pus or ichor being taken up into the mass of the blood. There are usually several of these abscesses present, and they may result in laceration or ulcerous perforation of the heart. Metastatic processes are always simultaneously present, to a considerable extent, in other organs.

D. Grangrene Of The Heart

There is nothing, d priori, at variance with the possibility of the occurrence of gangrene in the muscular substance of the heart. Ulcerations accompanied with malignant products are not of rare occurrence, but the correctness of the observations purporting to refer to gangrene of the heart, have nevertheless been called in question by several writers, and we must remark that no case of the kind has fallen under our notice.