This group of ulcers resembles the duodenal ulcer in that disturbances of the circulation are the exciting causes. These ulcers are of very rare occurrence. Embolic ulcers were first described by Parenski.1 They originate in consequence of emboli which are carried into the fine branches of the intestinal arteries, either from some abscess cavity or from a focus of atheroma or endarteritis.

The pathological changes of the intestine after such an occurrence are slight if a very small vessel, a capillary or an arteriole, has been occluded. In case the embolus is of an infectious nature, infiltration and formation of pus soon develop, and the process may quickly penetrate down to the serosa and infect the peritoneal cavity. It may also rapidly reach the intestinal lumen and thus produce an ulcer. In the infectious cases the fatal issue often ensues so quickly that there is hardly time for a complete formation of the ulcer. In such instances only the initial stages of the ulcerative process can be discovered. Fine nodules will be noticed in the intestinal wall originating from the submucosa and consisting of accumulations of round cells in the centre of which are very small blood-vessels.

1 Parenski: Wiener med. Jahrbucher, 1876, Heft 3.

The symptoms of these embolic ulcers are the same as those caused by other ulcerative processes of the intestines, namely, severe pain which may be of a colicky nature, tenderness on pressure over the abdomen, and diarrhoea with more or less bloody admixture. If these symptoms are present and embolic processes can be discovered in other organs, then the diagnosis of embolic ulcer of the intestine is probable.

The clinical symptoms and the anatomical changes resulting from the obstruction of a very small blood-vessel of the intestines are comparatively slight, compared to those which rapidly appear if the embolus has entered the arteria mesaraica superior. This affection is extremely rare; only nineteen cases have been described in literature. The emboli which have been found in the arteria mesaraica superior itself or in its branches could be traced to the left heart or to the aorta, which was the seat of excrescences due to endocarditis or atheroma. There is either a total obstruction of the entire mesaraic artery or several larger and numerous smaller branches of this vessel are occluded. The changes which frequently result after the embolus has excluded the organ from circulation are hemorrhagic infarcts and necrosis with partial peritonitis. According to Litton,1 after an occlusion of the arteria mesaraica superior or its branches, the intestine is deprived of all arterial blood, there being no vicarious blood current from any anastomoses of these vessels. The arteria mesaraica superior, although it forms anatomical anastomoses, acts functionally like a terminal artery.

The reason of this is that the anastomosing vessels are of a very small calibre and pursue a very long course, and hence the mesenteric arteries are not able sufficiently to supply with blood the region deprived of its circulation.

1 Litten: "Ueber die Folgen des Verschlusses der Arteria mesaraica superior." Virchow's Arch., Bd. 63.

The pathological changes which appear after the occlusion of this artery consist of venous hyperaemia, hemorrhagic extravasations, oedema, and necrosis. In that part of the mesentery and intestine which was supplied by this occluded vessel, the smaller arteries branching off from the latter are contracted and empty, while the veins of the serosa and mesentery are overfilled with blood. The mucous membrane appears dark red; the entire intestinal wall is oedematous and swollen; small hemorrhages exist all over the mucous membrane and in the mesentery; and the intestinal canal contains extravasated blood either fresh or tarry looking. If the process has lasted for some time, necrotic changes soon appear and the mucosa presents a dirty brownish-green appearance and may be wiped off from the other layers like a slimy coating. The serous layer may be the seat of inflammation not only over the involved intestinal segment, but also over other still healthy intestinal coils, the latter being agglutinated and covered with a deposit of fibrin.

In the peritoneal cavity there may be a bloody fluid or a purulent exudation.

The clinical symptoms of an embolus of the superior mesenteric artery have been best described by Gerhardt 1 and Kussmaul.2 They are not always alike, and two groups of cases may be easily discerned. In the one, being the larger, an intestinal hemorrhage is the feature most marked, in the other the affection presents the picture of intestinal occlusion with or without any signs of peritonitis. As a rule the disease sets in suddenly with violent colicky pains involving the entire abdomen or some portion of it, usually in the neighborhood of the navel. Soon the pains grow diffused and there is an extreme tenderness on pressure over the abdomen. Sometimes the pain is accompanied by vomiting; in rare instances, however, the pain may be entirely absent. Such a case has been mentioned by Nothnagel. Intestinal hemorrhage, which is the chief symptom, soon occurs. As a rule several bloody stools appear in succession, which have a dark, almost black, brown or tarry appearance and occasionally a very fetid odor. The blood of the hemorrhage, however, is not always necessarily voided per rectum, for it may remain in the intestinal canal. The symptoms, however, which characterize a profuse intestinal hemorrhage (falling of the body temperature and collapse) will never be missing.

In the second group of cases there are merely signs of an acute intestinal occlusion; pains, constipation, and peritonitis being the only symptoms.

1 Gerhardt: "Embolie der Arteriae mesentericae." Wurzburger mod. Zeitschr., 1863, Bd. iv.

2 Kussmaul: "Zur Embolie der Arteriae mesentericae. " Wurzburger med. Zeitschr, 1864, Bd. v.

The diagnosis of this affection can be made, according to Kussmaul and Gerhardt, in cases in which the source of the embolus can be determined. An intestinal hemorrhage occurs (for which no primary lesion exists), colicky pains of great violence and later a tympanitic swelling of the abdomen and exudations make their appearance. The diagnosis can be possibly made only if all the just mentioned points exist. Otherwise, especially if the intestinal hemorrhage is missing, the diagnosis cannot be made during life.

The prognosis of this affection is very grave. As a rule it ends fatally. It appears, however, according to Vir-chow, that in rare instances a recovery is possible after long illness, a collateral circulation having slowly developed.

With regard to treatment, there is no special indication for this affection. The symptoms will have to be treated as such.

Embolus of the inferior mesaraic artery is a very rare occurrence. Two cases have been described by Hegar 1 and Gerhardt. The prominent symptoms are violent colicky pains, tenesmus, and bloody stools. The mucous membrane of the small intestine remains normal, while that of the colon, S romanum, and rectum becomes intensely red, succulent, and contains effusions of blood here and there. Severe anatomical lesions of the intestines, however, are absent, for the circulation is quite quickly re-established through anastomosis with the superior mesenteric artery and with the rectal arteries of the hypogastric vessel.

Similar to the lesions of the embolic process of the superior mesaraic artery are the consequences which result from a thrombus within the mesenteric veins or the portal vein. A few cases of this nature have recently been observed by Pilliet,2 Grawitz,3 and Eisenlohr.4 The clinical picture of these cases is as follows: There appear suddenly violent colicky pains in the abdomen. The latter swells up and grows intensely painful on pressure. Often vomiting is present, occasionally haematemesis. There may be constipation or very frequent diarrhoeal and bloody movements. Accompanying these symptoms there is always collapse. The course is also a very rapid one, the fatal end appearing after two or three days. This affection is liable to occur in advanced pulmonary tuberculosis, in highly marasmic conditions like the malarial cachexia, then as a consequence of pressure of the portal vein, in cirrhosis and cancer of the liver. All abdominal neoplasms may likewise produce a thrombotic condition of the veins by pressure. The same may happen in chronic peritonitis by the formation of constricting cicatricial tissue. Similar processes also arise whenever the intestine experiences pressure or incarceration at a circumscribed spot.

The venous circulation becomes obstructed by the pressure, while the arterial blood supply owing to its elastic walls remains undisturbed. In consequence of the lacking out-flow of the blood, hyperaemia appears, then follow hemorrhagic infarcts, and lastly necrosis.

1 Hegar: " Embolie der Lungenarterie und der Arteria mesaraica inferior." Virchow's Arch., Bd. 93.

2 Pilliet: "Thromboses des veines mesaraiques. " Progres med., 1890. No. 25.

3 Grawitz: " Ein Fall von Embolie der Arteria mesaraica superior. " Virchow's Arch., Bd. 110.

4 Eisenlohr: "Zur Thrombose der Mesenterialvenen. " Jahrbucher der Hamburger Staatskraukenanstalten, 1890.

As the symptoms and treatment of the following classes of intestinal ulcers are identical, we shall discuss them together later on, after having first given the etiological and anatomical features of each separately.