The fringe of mucous membrane which lies upon the base of the ulcer, gradually connects itself, from without inwards, with the cellular tissue that invests the base, and uniting with it becomes paler and thinner. At the same time the cellular layer becomes whiter and denser, and is finally converted into a serous lamina, the circumference of which is dovetailed between the muscular and mucous coats. The margin of mucous membrane is bevelled off in such a manner, that the union is imperceptible; the former does not advance uniformly on all sides towards the centre of the ulcer, hence the elliptical is converted into a sinuous, the round into an elliptical ulcer. At the same time the margin, as well as the neighboring mucous membrane, are thinned down in such a manner, that at last their villi appear to have been transferred to the serous lamina. The edges unite finally at one or more spots, and coalesce. We have sometimes observed, that long before the union of the edges, small villosities formed independently on the serous lamina, a fact which has been also remarked by Sebastian.

Instead of the ulcer we find, in proportion as the above process is effected, a slight depression on the internal surface of the intestine, dependent upon the thinning of the mucous membrane and its connection with a thin cellular layer of denser structure, - or we find a spot at which the mucous membrane is more firmly attached and less movable, in the middle of which, by oblique light, we may often discover a smooth remainder of the serous lamina of the size of a millet-seed; or, if even this is not the case, we discover a spot at which the mucous membrane is more tense, void of plicae, smooth, less vascular than the surrounding portion, and particularly less villous.

Such cicatrices have occasionally been observed thirty years after the typhus had occurred.

It is singular, and characteristic of the typhous ulcer and its cicatrix, that it never in any way gives rise to a diminution of the calibre of the intestine.

The mesenteric glands in the meantime have returned to their normal size; they not unfrequently shrivel up, so as to become considerably smaller, and at the same time tough and pale.

Summary of the Alterations occurring in other Organs.

A. In The Abdominal Cavity

We find that here only the spleen and the venous system of the fundus ventriculi offer important and constant changes, although these do not belong exclusively to typhus, and still less to ileo-typhus.

The spleen is enlarged to from twice to six times its natural size, it swells, and its sheath becomes tense and smooth; the tissue of the organ is friable, and contains a dark purple or blackish-red, semi-coagulated, pultaceous, or perfectly fluid mass, which gives rise to a tumor of peculiar appearance, occasionally communicating the sense of fluctuation; not unfrequently a spontaneous rupture of the organ ensues.

At the fundus ventriculi we find venous congestion, which may be traced back to the vessels of the spleen, and which is either limited to the larger trunks or affects the capillary vessels in the tissue of the mucous membrane; jn the latter case, the mucous membrane of the fundus is dark red, lax, and turgid, and, in consequence, similar to the condition of the spleen, rather more friable than in the normal state. Allied to this condition is the first stage of softening, which, however, does not appear in the ordinary course of typhus.

B. In The Thorax

The bronchial mucous membrane and the parenchyma of the lungs present certain constant changes, which, however, vary in degree.

The former is affected by a peculiar catarrh, accompanied by dark-red discoloration, and the secretion of a viscid gelatinous mucus, which increases in amount as we descend to the smaller subdivisions of the bronchi; the pulmonary parenchyma presents symptoms of hypostatic congestion, which is generally limited to the posterior and lower portions; the tissue appears dark red, or purple, is filled with dark-colored glutinous blood, is denser, and resembles the spleen in consistency (splenification); this is sometimes increased to hepatization (pneumonia), though it is to be carefully distinguished from secondary, and still more, from primary pneumonic typhus.

The heart is commonly flaccid, its muscular portions are pale, or of a dirty-red color, but without any further anomaly, and more especially without that softening of its substance described by Stokes as occurring in the typhus fevers of Ireland. The endocardium and the lining membrane, or all the coats of the vascular trunks, frequently present a brown or purplish discoloration produced by imbibition.

C. Alterations In The Nervous System

The brain and the spinal cord and their membranes present the most various gradations with reference to the amount of blood they contain, from hyperaemia to anaemia; they sometimes are characterized by remarkable density and tenacity, sometimes by a humid and softened condition.

The 'double condition which is frequently and distinctly seen in the central ganglia of the vegetative system, is of still greater importance, and the results obtained at the Viennese Hospital, since the year 1824, with regard to this question, are in the main corroborated by the observations made at the Wurzburg school of medicine.

The ganglia of the solar and superior mesenteric plexus are, in the first stages of typhus, in a state of turgescence, with a blue or greenish-red discoloration; they are softened in the ulcerative stages, and subsequently we find them collapsed, pale, flaccid, shrivelled up as it were into coriaceous, tough, white or grayish masses.

We have never discovered in the nervous system the characters of genuine inflammation, a fact which is also established by the investigations of Rey, in opposition to those of Grossheim.