The fourth stage, or that of cicatrization, usually commences with the beginning of the fourth week. The swelling of the edges of the ulcers gradually diminishes, and they become adherent to the tissues beneath. The floor of the ulcers covers itself with delicate granulations, which in course of time are converted into connective tissue. This is ultimately coated with epithelium, but neither the villi nor the glands of the mucous membrane are ever reproduced. The resulting cicatrices may be recognized by the affected parts of the bowel being thin and more translucent than in health, and may retain these characters after the lapse of several years. They never give rise to contraction of the bowel. The time occupied in the cicatrization of each ulcer is said to be about two weeks. It occasionally happens that while cicatrization is taking place at one end of the ulcer the process of necrosis and ulceration is still going on at the other, so that two or more ulcers may occasionally run together. This form of ulcer may often retard recovery, and may sometimes end in perforation of the bowel, even after convalescence seems to have been established.

The color and consistence of the mucous membrane of the cæcum and colon are in a large proportion of cases normal. In a few the membrane is paler than in health, and in others it is of an ash-gray color. It is also sometimes injected and softened. The solitary glands are frequently enlarged and ulcerated, like those of the ileum. In the former case the mucous membranes of the large intestine throughout its whole extent, but especially that of the cæcum and of the part of the colon adjacent to it, is studded with minute elevations about a line in diameter. When ulceration has occurred the ulcers are generally round and small, but they may occasionally be oval and of considerable size. In the latter case their long diameter will correspond in direction with that of the circular fibres of the intestine. Murchison has known them to measure fully an inch and a half in length. The colon is generally found much distended with flatus.

Enlargement of the mesenteric glands from cellular hyperplasia and hypertrophy of the connective tissue is constantly associated with the morbid changes of the intestines just described. This enlargement varies in different cases. In some the glands are not larger than a pea or bean; in others they are said to have reached the size of a hen's egg. It is always more marked in the glands which lie in the angle between the lower end of the ileum and the cæcum, and usually bears some proportion to the intensity of the local disease; but it is not to be regarded merely as a result of the local irritation, as it has been observed in parts of the mesentery corresponding to perfectly healthy portions of the intestine, and as the meso-colic glands have been involved in cases in which the colon was free from disease. It has, moreover, been observed in cases in which death has occurred very early in the disease, and there can therefore be little doubt that it is as much the result of the infective process as the infiltration of Peyer's patches. In addition to being enlarged, if death has taken place before the end of the second week the glands are hyperæmic and of a purplish color. Later than this, when the sloughs become detached from Peyer's patches, the swelling of the glands diminishes; they lose their color and become pale, and if convalescence ensues they return finally to their former healthy condition. Still, Murchison has seen them shrivelled and pale or bluish for some time after convalescence. In other cases the substance of the glands softens, with the formation of a puriform liquid. If the softening only involves a small part of the glandular structure, restoration to health may take place through the absorption of this liquid. If it is more extensive, the whole of the glands may break down into this puriform liquid, which, when the patient recovers, undergoes caseous and finally calcareous degeneration. Occasionally, a gland in this condition is the cause of death from rupture and extravasation of its contents into the cavity of the peritoneum.

The glands in the fissure of the liver, the gastric, lumbar, inguinal glands, and indeed all the lymphatic glands in the body, have occasionally been found swollen and congested, but their enlargement cannot be classed among the specific lesions of the disease, but is merely the result of a local irritation. Thus, Jenner says that in the case of extensive ulceration of the oesophagus which came under his observation there was marked enlargement of the oesophageal glands. Liebermeister says that the lymphatic follicles which surround the glands at the root of the tongue and in the tonsils are often affected in the same way as the glands. In most cases after a time the swelling disappears, but sometimes softening and rupture take place.

The spleen is almost invariably found to be increased in volume and to have undergone changes in consistence and color. The degree of enlargement and the other changes vary of course with the stage of the disease at which death has occurred. The enlargement occurs with less frequency in elderly than in young people, and is most marked at the height of the disease, the organ being then often twice or three times its normal size, and in some cases, it is said, even larger. Later, and especially during convalescence, the enlargement has generally very much diminished. During the first ten days of the disease the spleen is generally tense and firm, engorged with blood, and dark red in color. Between the tenth and thirtieth days its appearance remains the same, but the organ is found to be soft and friable. During convalescence it becomes paler and firmer again, and is often so shrunken in size that its capsule is relaxed and wrinkled. Hemorrhagic infarctions are often met with. These sometimes soften and break down into a puriform liquid, which may sometimes cause peritonitis by rupture into the peritoneal cavity. Rupture of the spleen is also said to have occurred from mechanical violence. These changes are due in part to variations in the amount of blood, and in part to a medullary infiltration of Malpighian corpuscles similar to that which takes place in Peyer's patches and the glands of the mesentery.

LESIONS WHICH ARE NOT PECULIAR TO TYPHOID FEVER, BUT ARE OF MORE OR LESS FREQUENT OCCURRENCE.—The mucous membrane of the pharynx and oesophagus may present a perfectly healthy appearance, but occasionally it is congested and the seat of ulcerations which are for the most part superficial. Sometimes, however, they have been found to extend to the muscular coat, but they have never been known to penetrate all the coats of these organs. Jenner refers to one case in which there was extensive ulceration of the oesophagus, but usually the number of ulcers is not large. In a few cases the mucous membrane of the pharynx is coated with diphtheritic false membrane, and the submucous tissue is infiltrated with serum and pus (Murchison).

The stomach and the upper part of the intestinal tract present no lesions which are at all peculiar to typhoid fever. In a certain number of cases congestion, softening, and even superficial ulceration, of the mucous membrane of the stomach, and less frequently of that of the duodenum, have been found. The mucous membrane of the jejunum and of the upper part of the ileum is not usually much reddened, and may be even paler than in health. In cases which have been protracted it may be of an ashy-gray or slate color. The contents of this part of the intestinal tract, which is rarely much distended by flatus, do not differ materially in appearance or consistence from the matter which generally composes the typhoid stool. The bowels may, of course, be found filled with blood in cases in which a recent hemorrhage has taken place. Invaginations of the small intestines, unaccompanied by any evidences of inflammation, are occasionally met with in the bodies of those who have died of typhoid fever. They are produced, there is good reason to believe, during the death agony, but are not peculiar to this disease, as they occur in many other diseases.

Enlargement of the liver has been found in only a few cases after death from typhoid fever. Softening is more common, but even this is not a frequent result of the disease, for it was absent in 41 out of 73 cases examined with special reference to this point by Louis, Jenner, and Murchison. The organ is occasionally hyperæmic, and darker in color than in health, but it is oftener pale or normal in appearance. Even, however, where it appears to be perfectly healthy to the unassisted eye, the microscope shows that its cells are very granular and filled with oil-globules which often render the nucleus indistinct or completely conceal it. When death has taken place at an advanced stage of the disease many of the cells are found to be completely broken down into a granular detritus. These changes are usually proportional to the degree of pyrexia which has been present during life. Rarer lesions of the liver are pyæmic deposits, embolism, abscess, and emphysema.

The mucous membrane of the gall-bladder has been found to be the seat of ulcers by Jenner and numerous other observers. It also occasionally presents the evidences of catarrhal or diphtheritic inflammation. The gall-bladder usually contains a pale watery liquid of a less density than bile. When, however, inflammation of its lining membrane has existed, its contents are mixed with pus and shreds of false membrane.

The mucous membrane of the larynx is sometimes found to have been the seat of catarrhal or diphtheritic inflammation, and sometimes also of ulceration. Jenner says that in typhoid fever laryngitis independent of pharyngitis is extremely rare, but the German writers express a different opinion. Griesinger estimated that laryngeal ulcers were present in one-fifth of the fatal cases. Hoffmann found them twenty-eight times in two hundred and fifty autopsies, and that the ulcers had extended to and involved the cartilages in twenty-two out of the twenty-eight cases. They are most commonly found in the posterior wall of the larynx, and may involve the vocal cords. These are often discovered after death in cases in which their existence was not suspected during life. They were formerly supposed to be the result of typhoid infiltration of the laryngeal glands, but careful investigation has shown that they are the consequence of diphtheritic inflammation of the mucous membranes. Inflammation and ulceration of the trachea are comparatively rare. Hypostatic congestion and infarction of the lungs are not uncommonly found after death from typhoid fever, and less frequently the lesions of pneumonia. Evidences of recent pleurisy are also discovered in a few cases. Acute miliary tuberculosis of the lungs is more often met with as a sequela than as a complication.