Those persons who believe this disease to be a primitive monstrosity are divided into two classes. The one suppose it to be merely an organic deviation, in which the urethra is placed above instead of gliding beneath the pubis. This, however, is not the prevailing doctrine; that which has obtained the most general currency is based upon the theory of arrested development. Supposing that the two moieties of the body do not, until late, meet upon the median line anteriorly, they say, if, by any cause, the sides of the hypo gastric parietes cease to advance, the one to wards the other, during their allotted time, the bladder will pass between them, and will soon lose its anterior moiety, supposing this moiety to be already formed, from whence the fungous state which it offers after birth. So powerful are the authorities by which this mode of explaining the phenomena is supported, so completely is it said by the ardent supporters of teratology to be in consonance with its principles, that it would appear to be almost heretical to support a somewhat different view of the subject taken by M. Velpeau. He be lieves that extrophy of the bladder is not simply owing to an arrested development, first, because in the normal state the bladder is neither split nor open, neither anteriorly nor posteriorly; secondly, because the pubic circle is completely formed before the bladder is per ceptible; thirdly, because the aspect of the fissure that the urinary sac should present never exists; and, fourthly, because the theory in question has for its support only such ana logies as do not appear to us to have been completely established. If an hypothesis be required, it appears to be more in conso nance with observation to assume that this vice depends upon an alteration of the abdo men, either pathological or purely mechanical, contracted during embryo life. The parietes of the abdomen are extremely attenuated and fragile up to between the second and third months, and for some time beyond this the parietes do not acquire any thing like the density below that they do above the umbilicus. At this time the space is so small between the umbilicus and the sexual organs, that the smallest fissure may become the origin of a large ulceration, and such lesions are seen at all degrees. Indeed it is scarcely possible to set forth the variety of lesions to which the young foetus is subject : foetuses have been seen in which the parietes of the abdomen were alone destroyed. In one of three months the bladder was already comprised in such a perforation, and the borders of the whole were so jagged, thin, and unequal, that it t ould be referred to nothing else than a laceration. It is held in this place, therefore, that extrophy is frequently a disease, or the•effect of a diseases, but not a monstrosity; an ulceration, a perfo ration of the penis or of the hypogastrium, being the common point of origin. The bladder is only secondarily altered. If the fcetus continues to live, the borders of the de stroyed bladder are united to the circumference of the abdominal opening, or, at least, to the posterior surface of the remaining portion of the hypogastrium. The cicatrisation once ef fected, the rest is explained by the mucous nature of the organic septum, which occupies the place of the pelvic or abdominal parietes. The umbilicus may or may not be implicated in the loss of substance ; the pubes, which are commonly destroyed, and not simply sepa rated as has been believed, may be also pre served ; and the vesical tumour may in some cases only occupy a space of a few lines, whilst in others it may implicate a great por tion of the hypogastriurn.
Those organs which are normally in relation with the pubis present certain anomalies in extroversion of the bladder, which should be mentioned in this place. The ureters, of course, open immediately upon the surface of the body ; the urethra no longer serves for the emission of urine, and is often incomplete.
Commonly in woman it opens above the cli toris, in man above the penis. Occasionally the testicles do not descend. Meckel has remarked that there is commonly a separation of the two lateral moieties of the external genital organs, like that of the abdominal muscles and the pubis. It has been remarked by Duncan (loc. cit.) that this infirmity more commonly happens to the male than the female. Meckel doubts this proposition, and adds many cases to those cited by Duncan, in which the disease affected the female. Isidore Geoffroy St. Hilaire, who has carefully examined the recorded cases, which are now very numerous, supports the conclusion of Duncan : he says that of these one-fourth appertain to females, nearly two-thirds to males, and in the re mainder the sex was undetermined. Ex trophy of the bladder is a very serious af fliction, because of the incontinence of urine which is its inevitable consequence, and the deformity of the genital organs by which it is constantly accompanied, and which, in man especially, very commonly occasions impo tence. It constitutes a more serious disease in the male than in the female, for in the latter the external genital organs, except the want of projection of the pubic eminence, commonly suffer only slight modifications of form : the ovaries, the uterus, and their appendages may not even present any anomalies.'' Persistaacc the urachus.—The last of the congenital malformations to which I shall allude is the persistance of the urachus some times even to adult age. For a considerable time much doubt was expressed whether the urachus was ever a canal, pervious from the bladder to the umbilicus ; and it was not gene rally admitted until the fact had been re peatedly demonstrated by Haller and his pupil Noreen. In January, 1787, Boyer exhibited a bladder taken from a man aged thirty-six, in which the urachus formed a canal an inch and a half long, and containing twelve urinary calculi, each of the size of a millet-seed; and it was demonstrated this canal was not a vesical sac or a prolongation of the mucous membrane. But these cases of persistance of the cavity of the urachus in adult or even in infant life are unquestionably extremely rare ; and it is certain that a protrusion of the mu cous tunic in the form of a canal at this point has been mistaken for the canal of the urachus ; it is even probable that generally where the urine is prevented from escaping by the urethra, and where it escapes by the umbi licus, it results from the rupture of the species of hernia formed near the situation of the urachus by the mucous tunic of the bladder, and not from the dilatation of this membranous cord.
When this canal remains pervious only in a part of its extent, the anomaly is not indicated externally. When its cavity is preserved even from the bladder to the umbilicus, nothing marks its existence at the exterior if the urinary passages are unobstructed ; in the opposite condition a very remarkable physiological ano maly accompanies it, and reveals the presence of the anatomical anomaly; it is the total or partial excretion of urine by the umbilicus, either constantly and from the moment of birth, which is the case when a vice of confor mation or a disease prevents the urine from passing by its natural channel ;$ or tempo rarily, when the course of the urine, which was at first by the urethra, comes to be inter rupted by any cause.
Sigismund Konigt relates the case of a woman in whom the urine, usually excreted by the urethra, passed by the umbilicus during some days in consequence of a severe labour ; but this example and others which might be mentioned do not appear to possess the authen ticity which is required to establish" that this infirmity may be acquired. It is probable that many of these cases were simply a hernia of the mucous membrane of the bladder, such as occurred in the case detailed by Portal.t