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Show I860.] IN THE GENERATIVE ORGANS OF A COW. 599 modern anatomists refer them with justice to defects in the develope-ment of the embryo*, assuming that the organs undergo a certain transformation from a simple common type into one or other of the sexes-although there are not wanting those t who have entertained the view that the hermaphroditic or bisexual condition of the embryo is the original one. Without entering into the latter hypothesis, ably opposed by erudite authority J, we shall merely consider how far the present example of malformation agrees with or bears out the history of embryonic development. In the description of the dissection of the parts of generation it was shown that the bladder entered into the vagina, and that from these a common urino-genital canal continued onwards to the external abdominal walls, this being the main point of resemblance to male sexual organization. It is interesting therefore to find that this precisely corresponds to a certain stage in foetal formation. The researches of many distinguished embryologists so far concur as to demonstrate that, after the intestine has been occluded from the umbilical vesicle with a partial dilatation of the urachus ultimately forming the urinary bladder, there still remains a common outward passage between the urinary and internal generative parts, the urino-genital sinus. Afterwards in the female this sinus becomes divided, and forms the narrow neck of the bladder and widish vagina, while in the male the meatus urinarius continues the principal canal. The external organs of generation, however, are of later development, and in both sexes at first identical, even in ruminants, where, as Johannes Miiller§ remarks, he had hoped to find an early difference, seeing that the sheath of the penis in the male adult opens close to the umbilicus. According to the same talented observer, the embryos of sheep have a proportionally long clitoris or penis. In the female this shortens ; in the male it lengthens. In the latter, at a later period, by an agglutination of the sheath, it is attached at the same time to the abdominal walls, ultimately opening a short distance behind the navel. The perineal cleft, from its open condition, closes, leaving traces of its separation in the raphe. Later investigators, Kolliker || among others, in the main substantiate these earlier observations of Miiller. Having thus succinctly glanced at the course of development of such of the urinary and genital apparatus more immediately concerning those parts implicated in the structure of the malformation in question, it remains but to consider how such history applies to its abnormal condition. This brings us to conclude that in the earliest stage of the animal's * See the excellent article by Bischoff in Wagner's ' Handworterbuch der Phy-siologie,' 1842, vol. i. p. 860. t Dr. Knox, in Brewster's ' Edinb. Journal of Science,' vol. ii. p. 322, and paper reprinted from the 'London Medical Gazette' (1813), "Hermaphroditism: a memoir read to the Royal Society of Edinburgh in 1827 and 1828." t Prof. Simpson, in the ' Cyclop, of Anat. and Physiol.' vol. ii. p. 728. § Bildungsgeschichte der Genitalien aus anatomiscben Untersuchungen am Embryonen des Menschen und der Thiere (Dusseldorf, 1830). II Entwickelung des Menschen und der hoheren Thiere. |
