To the latter belong biliary calculi, which have reached the intestine by the natural passages, or by ulcerative communication; and the fatty and chalky concretions which have formed in abscesses adjoining the intestine and have passed into the latter.

Intestinal concretions prove injurious to the intestine, in proportion to their size and form, as we shall have occasion to explain further on.

With regard to serous, muco-serous, albuminous, puriform, and purulent discharges, to fibrinous coagula, and pseudo-membranous formations in the intestine, we refer to the remarks given under these heads.

6. Blood is found in large or small quantities, coagulated and fluid, red or variously discolored, in the vicinity of the point at which it was discharged, or extended over a large surface. Hemorrhage occurs in consequence -

Firstly; Of active, passive, and especially of mechanical hyperaemia; the latter being a frequent result of obstacles in the portal system. The mucous membrane presents no essential textural alterations, but is either congested and suffused, or in consequence of the excessive hemorrhage, pale and anaemic. The source of hemorrhage is scarcely discoverable. We have lately seen two remarkable cases of this description, in which exhausting hemorrhage resulted from intense and extensive burns of the abdomen.

Secondly; In consequence of the various exudative processes accompanied by solution of the mucous tissue and its vessels, e. g. in dysentery.

Thirdly; The hemorrhage may be caused by other morbid degenerations of the mucous tissue, e. g. erectile fungoid excrescences, the typhous deposit at the period of metamorphosis, or torpid ulcers.

Fourthly; In rare cases the hemorrhage results from the rupture of a varicose vein in the submucous tissue of the intestine, the investing mucous membrane giving way at the same time. It is more frequently caused by corrosion of an artery or vein at the base of a hemorrhoidal ulcer of the rectum.

Every variety of hemorrhage, but especially the one first cited, is favored by diminished density of the blood.

When the blood is found extravasated over a large surface, it may have come from above, but it frequently happens that the source of the hemorrhage is below the extravasation; this is particularly the case in hemorrhage of the rectum.

Moreover, the blood may have reached the intestine from the stomach, the oesophagus, the hepatic viscera, and even from the respiratory organs.

The longer the blood remains in the intestine, the longer it has been exposed to the operation of the intestinal secretions, the more it becomes discolored, assuming a chocolate or black tinge; and when it has experienced the influence of the gastric juice, it is frequently converted into a pitchy or tarry mass. Bile in a very concentrated form often presents a similar appearance.

The intestine sometimes offers a passage by which acephalo-cysts of the liver (the so-called hydatids) are discharged.

7. We must lastly investigate the foreign bodies found in the intestine.

To this class belong concretions formed within the body, and especially in the biliary ducts, and substances that have been introduced by mouth or per anum. They prove injurious by producing lesions of the intestinal parietes, as in the case of rough or pointed bodies, bones or fragments of bone, portions of stone, glass, needles, etc. After attaching themselves to the mucous membrane, suppuration is established, and they may thus escape through the intestinal and abdominal parietes; or the perforation may communicate with another portion of intestine, or with a neighboring hollow organ, and the escape be effected through the urinary and genital organs. The foreign bodies may also block up the intestine and induce ileus; these cases are of extreme importance, and they admit of the following subdivision:

Firstly, The foreign body is arrested at a certain point of the intestine, in consequence of its rough and angular form.

Secondly, the foreign body is retained simply from a disproportion between the calibre of the intestine and the size of the substance, and occlusion is the result.

Thirdly, The foreign bodies accumulate to a considerable number at one point, and the consequent extreme dilatation and paralysis of the intestine induce obstruction.

Rough, angular bodies, if not very large, frequently pass through the intestine without difficulty, in an envelope of mucous and feculent matter; but they often become attached to the intestine, by inserting their edges and processes into it, and may, by the consequent inflammatory swelling, give rise to an obliteration of the passage.

Large round or oval bodies, with a smooth surface, may be retained at various points of the small intestine, but especially at the terminal portion of the ileum, which presents a distinct diminution in calibre.

We class among these foreign bodies large biliary calculi, which have escaped from the bile-ducts into the intestine.

Indigestible substances that have been taken in large quantities, especially the peel of fruit, cherry, and plum stones, often accumulate at particular points of the colon, as the caecum or the sigmoid flexure. They give rise to uniform or lateral dilatation of the intestine, accompanied by atony and paralysis of the latter. This condition may, sooner or later, in a ratio with the size of the accumulated mass, give rise to ileus; or if the accumulation is inconsiderable, and the action of the superior portion of the intestine capable of effecting a partial discharge, it may last a considerable time, and end in a cure; or it results in chronic inflammation, the formation of sinuses, and the ultimate contraction of the intestine, which again may give rise to occlusion.