The aperture through which the ectopia takes place has a constant tendency to close ; it shrinks therefore sometimes to a very small opening (Hammer). Sometimes it is closed in the middle, by a band which separates the uncovered viscera into two portions (Iliihner, Wolff).
Its principal forms are : — 1. Fissure of the whole anterior Wall of the Body.
a. Complete ectopia of the thoracic and abdo minal viscera, which lie bare upon the anterior surface of the body, to which is generally added a cloaca. (Fig. 600.) The skeleton is very imperfect, in this com plete ectopia ; the thorax open, and the ver tebral column misformed by scotiosis.— This may produce, as often met with in calves, a complete inversion of the body, so that through distortion of the spine, the head is placed between the hind feet. This is what Gurlt calls schistozonzus reflexus, and what I represent in fig. 601.
Ectopia of the heart. — In the regular evo lution of the fcetus, the opening on the anterior wall of the body closes itself, first at its superior part, so as to cover the thoracic viscera, while a part of the abdominal intes tines still remain out of their cavity and in the sheath of the umbilical cord. Thus the thoracic cavity is in general already closed, whilst the abdominal is yet open. Neverthe less, it sometimes happens that the abdominal cavity is completed, and that its viscera are perfectly enclosed, whilst the thorax remains open, and the heart is placed on its anterior surface. In this malformation, called eclopia cordis, the heart has no pericardium, and is situated on the median line of the anterior wall of the thorax ; it is more or less rounded, and in general well formed, as may be seen in 595. The sternum is wanting (Tournelle, Norand, Sandifort); divided into two parts (Buttner, Martinez) ; or formed only by the manubrium (Manchardt). It is rarely com plete ; but this is often the case when the heart protrudes at the neck (Muse, Bubon nais, Breschet), or in the epigastric region (Wilson).
During fcetal life, the ectopia of the heart is immaterial, but soon after birth it causes the death of the child. Cruveilhier published some interesting observations on the move ments of the heart in a case in which life was protracted for a longer time than usual.* a. Complete ectopia of the abdominal viscera.
—The abdominal cavity is in general the last closed. When it alone remains open, the abdominal viscera only lie out of the body. The fissure is mostly extended from the ensi form process of the sternum to the pubic bones. One of the umbilical arteries is in ge neral wanting. Commonly this malformation is complicated with adhesion of the membranes of the ovum or of the placenta to the divided integuments of the abdomen, with a cloaca, with defective generative or uropoietic organs, and with an incomplete pubic articulation..
b. Congenital umbilical hernia. — In a less degree of deformity, the fissure is limited to the epigastric region, above the insertion of the umbilical cord, because this part of the abdomen remains longest open. This gives origin to congenital umbilical hernia. — The umbilical cord passes under the viscera, which lie exposed, or are only covered by the peri toneum. In the last case a sort of hernial sac is formed, which has a cylindrical or glo bular form, and is produced by the two coats of the ovum.
The external coat is that pirt of the amnion which is the covering of the umbilical cord ; the internal, the peritoneum, which is con sidered by Meckel as a continuation of the chorion from the umbilical cord. All these facts prove that congenital umbilical hernia is caused by an arrest of developement at that stage, in which a part of the abdominal viscera are contained in the sheath of the umbilical cord, The size of the tumor is variously modified by the number and by the volume of the viscera contained in it. When it contains the liver, it is of a bluish colour. The viscera lying in it, are always in an imperfect con dition. Only four cases are known, in which the life of the malformed child lasted for any time after birth (Meckel, Cruveilhier, Ribke, Van der Voort) ; in the case of Van der Voort for eight, in that of Ribke for twelve months. In all these cases the external coat of the hernial sac has mortified, and the tu mor has become gradually covered by the skin. An accurate diagnosis of this malformation is of great value. In two cases, in which it was not accurately recognised, a ligature was put round the tumor, and it was cut off. One of these cases was the subject of an interesting law proceeding.