The very important conclusions to be derived from pathological anatomy in reference to inflammation of this organ, and with regard to its influence upon sanguification, will be self-evident.

We cannot doubt that the pulpy substance of the spleen may be the original seat of inflammatory action; the fact has not, however, been as yet anatomically demonstrated; in the same manner it is not improbable, though by no means proved, that many acute and chronic tumors of the spleen may be the product of inflammation.

The variety of inflammation for which pathological anatomy affords an explanation is, to name it from its seat, phlebitis, i. e., an inflammation of the numerous anastomosing and tortuous venous canals of the spleen. In fact, we have only to apply the doctrines promulgated with regard to inflammation of a vein to a venous ganglion, in order to obtain a correct picture of inflammation of the spleen; that which elsewhere takes place in a simple vascular tube is here found in a complicated venous apparatus.

This inflammation of the spleen occurs as a primary or as a secondary affection. Whilst the former is as rare as spontaneous primary inflammation of a vein, the latter is as frequent as secondary phlebitis.

Primary inflammation of the spleen, if not early combated, or unless ending in resolution, gives rise to an exudation of laudable pus or fibrine. In either case the circulating fluid may become infected, and coagulation be produced in the most various regions of the vascular, and especially in the capillary system. This is an explanation of so-called metastases. However, this is unusual in the case of fibrinous exudation, as the inflamed vessels are closed by the coagula, causing obliteration and subsequent conversion of the inflamed part of the spleen into a fibro-cellular callus, which may even ossify.

In the case of purulent exudation, inflammation of the spleen passes into suppuration, and abscesses form. In a favorable case, the abscess may be circumscribed by adhesive inflammation, and, being enclosed in a sac formed by obliterated parenchyma, which has been converted into fibrous tissue, may be borne for a long period]; a partial absorption of the pus may take place, and the remainder becoming inspissated be reduced to a calcareous greasy pulp, or even to a hard concretion. The more common case is that the parietes of the abscess also put on inflammatory action, and suppurate, in consequence of which the abscess generally enlarges very rapidly, with symptoms of violent and universal reaction in the shape of hectic fever. We then have a case of florid (floride) splenic phthisis.

If the inflammation extends to the sheath of the spleen, inflammation of the splenic and neighboring peritoneal surface ensues; an occurrence which is analogous to the communication of disease from an inflamed vessel to the tissues in its vicinity: the inflammation is not, however, apt to spread far.

The splenic abscess not unfrequently discharges:

Firstly, Into the abdominal cavity; the pus is then often enclosed by the product of circumscribed peritonitis, which causes the formation of a sac, bounded by the external wall of the abdomen and the diaphragm, the fundus ventriculi, the colon, and its mesentery; the entire spleen is thus occasionally destroyed by suppuration.

Secondly, Into the left thoracic cavity, after suppurative destruction of the diaphragm, or:

Thirdly, Into the cavity of the transverse colon, and into the stomach.

Secondary inflammation of the spleen is of frequent occurrence in all cases in which the blood is poisoned by the absorption of an inflammatory product, or has become affected in an analogous way spontaneously, a fact which indicates the delicate reaction of the spleen to a morbid condition of the blood. We then see the formation of inflammatory spots, which are in every way remarkable. They are well defined; they always occupy the peripheral portion of the organ, and generally present a cuneiform shape, the base being at the surface, the apex being directed towards the interior; there are often two, three, four, and more of these foci present at the same time; they vary in size from that of a pea, to that of a hen's egg, and in rare cases involve an entire third of the viscus.

The substance of the spleen appears considerably darker at these spots, from the commencement, and also denser and more resistant; it subsequently assumes a reddish-brown color, and its density also increases, so that the affection* may be at once identified, even externally; its limits are now well defined, and reactive inflammation is set up in the adjoining tissue. The process may terminate in various ways: in favorable cases, especially when a benignant fibrinous exudation has been absorbed into the blood, as frequently occurs in inflammation of the internal membrane of the bloodvessels, and particularly of the endocardium, the diseased tissue is converted into a cellulo-fibrous callus, which contracts and causes a cicatrix at the surface, by drawing the sheath of the spleen inwards. The more common case is that pus or ichorous matter is absorbed, and that the inflamed portion is converted into a puriform, creamy mass, or into a sanious, greenish, greenish-brown, or chocolate-colored pulp; in the latter instance, the conversion is often effected with very violent symptoms, without previous induction of the paleness above described.

The entire process is a detailed repetition of that occurring in secondary phlebitis, and is nothing more than the metamorphosis of an infected coagulum within the channels of a vascular ganglion.

When the disease affects the peripheral portions of the organ, peritonitis frequently supervenes, and an eschar having formed in the sero-fibrous sheath, a discharge into the abdominal cavity is not rarely effected.

This secondary inflammation of the spleen is a very frequent complication of inflammation of the internal vascular coat, and particularly of endocarditis. Of all organs that are affected in a similar manner, by the absorption of a product of inflammation into the blood, the spleen is the most liable to be attacked. When occurring as a result of spontaneous disorganization of the blood, it is particularly important in complication with croup, as also with exudative processes on mucous and serous membranes, particularly with pneumonia, and, lastly, with the analogous process of tubercular disease.