1. Defective And Excessive Formation

A complete absence of the intestinal canal when an abdominal cavity existed, has probably never been observed. It is frequently defective; at times it is a short tube of uniform calibre, attached to a flat narrow strip of mesentery, or it consists of several detached portions of intestine which are strung together on a very defective fold of the peritoneum.

We must here mention the blind termination of the intestine at different points of its course, there being either a fresh acuminated commencement lower down, or an absence of the remaining portion. The most frequent anomaly is the more or less extensive deficiency of the rectum with a consequent atresia ani. The latter abnormities demand the formation of an artificial anus at the natural situation, or at some other suitable part, if they occur in individuals who are otherwise capable of sustaining life.

Defective formation may occur in the shape of tissue, of irregular communication of the intestinal tube, as in the case of the latter discharging at the navel, into the cavity of the urinary or small sexual organs (cloaca); it then is commonly the result of an arrest of development.

Excess of development, with the exception of the various degrees of biventral monstrosities, is probably nothing but a deceptive appearance; the repetition of some of its segments, and the presence of larger or smaller blind appendices, which open outwards or into the intestine, and more especially the so-called diverticula, are almost invariably to be considered as arrests of formation.

The latter, the congenital diverticula, Meckel's diverticulum verum, deserve a special consideration. It is a dilatation of the small intestine, representing a hollow appendix, which consists of all the intestinal membranes, and is placed at from eighteen to twenty-four inches from the caecal valve; although we do not quite assent to Meckel's view, that it is a remnant of the umbilical canal, it evidently has its origin in the development of the intestine in the umbilical vesicle. We accordingly always find it solitary and attached at the above-mentioned spot; it varies in length from five to six inches; it sometimes is wider, sometimes narrower, than the intestine itself; it is frequently contracted at intervals, of a conical or cylindrical shape, and terminating in a round, clubbed, or lobulated expansion. It either projects at right angles from the convex surface of the intestine, hanging unattached in the abdomen, or it passes off at an acute angle from the concave surface of the intestine near the mesenteric insertion, being attached to the latter by a falciform process of the peritoneum. In this case it is often placed parallel to the intestine. Occasionally a ligamentous cord, the remains of the omphalo-meseraic vessels, is found at its free extremity, and as this may, by its adhesion to various points of the peritoneal cavity, give rise to internal hernia (strangulation of the intestine), it receives importance in a pathognomonic point of view.

The following case, in which this appendix was abortive, may be interesting: In the corpse of a young man, the small intestine was found enlarged at the above-mentioned spot, to the extent of several inches, the peritoneum and the adjoining laminae of the mesentery were white and opaque, studded with tendinous patches, and a tolerably long ligamentous cord, the remains of the bloodvessels, was found depending from a rounded embossed dilatation.

We may finally observe that the entire intestinal canal or portions of it, are found in some individuals inordinately long or short; no fixed rule has, however, been established with regard to the relation among the parts themselves, to the stomach, the organs of mastication, etc.