In the female chick, according to Minter, there is always seen an oviduct (fig. 400. g), distinct from the duct of the Wolffian body (fig.400.f). In the male, however, he has been able to detect no vas deferens distinct from the excretory duct of the corpus Wolffianum ; but on the contrary, the testis and the excre tory duct of the former body seem tcr become connected by means of vasa efferentia. This is an important point, because it will be found so far to bear out the views of Kobelt re garding the homologies of these structures.
In the mammalia generally, and in man, the Wolffian bodies are less extended. They, however, possess the same arrangement of tranmerse cwcal tubes ( fig. 401. a—d), ter ininating in the side of a common excretory duct (e), which leads from the lower extre mity of the orean to the uro-genital sinus.
These structures are all formed indepen dently of the kidneys and supra-renal cap sules, as well as of the ovaria and testes, which parts occupy the same relative position in niammalia as in birds.
But here, according to Miller's researches, a different arrangetnent is observed in regard to the efferent duct of the generative portion of these structures. At first the oviduct and the vas deferens have each the same confor mation, and each terminates by a free extre mity. This, in the female, merely acquires an open mouth, and thus the Fallopian tube is fornied, the ovary continuing, as at first, distinct and separate. But in the male the efferent tube and the testis become connected by transverse vessels, which are afterwards converted into the coni vasculosi of the epi didymis, whilst the rest of that organ is com posed of the convolutions of the efferent tube itself. " The Wolffian bodies entirely dis appear in both sexes, and are not converted into any other organ." * These views, however, leave unexplained many peculiarities which are observable in the permanent condition of the parts or or gans developed from the fcetal structures ; and it is the great merit of Kobelt's rq, searches that they serve to render these in telligible.
According to this observer, there exists, in the earliest periods of intra-uterine life, a condition of indistinction of sex in every in dividual. This depends upon a temporary co-existence in each individual of all the ele ments of the reproductive structures. For at the highest point of sexual indifference, that is, shortly before the beginning of the di%ision of sex, the Wolffian bodies consist of — 1. The so-called excel tubes (fig. 401. a—d).
2. Of the common duct (e) running along the outer side of this body, into which the cmcal tubes open.
3. And of a second longer cord (h), which begins in a blind pouch (i), and takes its course inwards over the Wolffian body, pa rallel with the excretory duct of the latter (e), in order to enter the uro-genital canal (x), by a separate orifice (k). This last cord,
discovered by John Miller, is throughout destitute of any connection with the meal pouches. (See alsofig. 400. g.) The organ destined for the preparation of the reproductive material, the generative gland, (fig. 401. / ), consists of a longish, clearly defined structure, lying upon the inner side of the Wolffian body, so as to cover a portion of the bulbs of the cwcal pouches. Its white colour serves to distinguish it, at a glance, from the 3 ellowish brown Wolffian body. As yet, no material nor actual distinc tion of sex can be discovered in any one of these parts ; and yet the whole already con tains all the elements of the male, as well as of the female, reproductive apparatus, without any true exhibition of bi-sexuality.
The nature of the first impulse towards a division of sex, in one or other direction, is unknown, but the subsequent separation ma nifests itself with the commencing distinctive development, and correlative retro,gression of each several element ; for the cardinal organ, the generative gland (fig.401./), rnay be con verted into testis (fig. 402. /), or ovary (fig. 403. /), and through the doubly existing ex cretory duct of this gland, viz. the duct of Miiller (fig. 401.h), for the female, and the excretory. duct of the Wolffian body (fig.401, e) for the male, the capability of conver sion into either sex exists at this time in every individual.
The division of sex begins to be anatomi cally discoverable by the development of one, and the stationary condition or disappearance of the other of these ducts. From this point, therefore, the courbe which each of these organs takes, is different for either sex. The male Wolffian body never disappears in all its parts, but is converted into the epididy mis in such a tnanner that the middle line of meal tubes (fig. 40I.e c) is transformed into the 18-20 coni vasculosi (fig. 402. e); while their straight and open ends, as vasa efferen tia, establish a communication with the rete vasculosnm testis. The upper blind pouches (fig.401. a, b) and the bulb (f) of the excre tory duct disappear, or become converted into the hydatids (fig. 402. I), f) upon the head of the epididymis, while the inferior pouches (A. 401. d) disappear in part, and in part become elongated and tortuous, without forming any connection with the testis. These constitute the hitherto enigmatical vasa aber rantia of Haller (fig. 402. d).