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Show 424 DR. M. WATSON ON THE MALE [Apr. 16, called spongy portion of the male urethra with that portion of the urino-genital canal which, in the female, lies in relation to the clitoris, is manifest. The erectile organ is of the same size, and constructed upon the same plan, in both sexes, the only difference being that in the female the urino-genital canal is not surrounded by the erectile tissue of the corpus spongiosum as is the case in the male, this difference being due to the fact that in the latter the essentially bilateral spongy bodies have coalesced in the middle line, whilst in the female, in accordance with physiological requirements, they remain distinct throughout life, and do not surround the sexual canal. In the female, moreover, and associated with this arrangement, there is a complete absence of the elevator urethras and bulbo-cavernosi muscles. It may be well now to ascertain whether the examination of this animal throws any light upon the subject of the probable homo-logues of the vagina and uterus in the male mammal. The majority of embryologists (among whom I may mention the names of Leuckart, Kolliker, and Allen Thomson) are now agreed that the so-called utriculus of the male mammal represents both the uterus and vagina of the other sex, these organs being formed by the coalescence of the ducts of Miiller. I have, however, in a previous paper remarked concerning the corpus uteri of the female H. crocuta, " That the whole of this is to be regarded as corpus uteri, and not as constituting any portion of the vagina, is proved by the absence of any constriction in its interior which might correspond to an os uteri, the tubular body of the uterus remaining of the same calibre, and having the walls of uniform thickness down to its opening into the urino-genital canal." It is evident therefore that in the female H. crocuta, the vagina being altogether absent, we must conclude that in the male of this species the utriculus represents the uterus alone, and not the uterus and vagina together. The same remark holds good, so far as I can ascertain, of only one other placental mammal- that is, of the Indian Elephant, in the female of which, as Mayer1 pointed out, the vagina is altogether absent, and the uterus opens directly into the urino-genital canal. In the male, therefore, of that animal, as in that of H. crocuta, the utriculus, as shown by Leuckart2, clearly corresponds to the uterus, and to the uterus alone, of the female. With reference to the homologue of the prostate gland in the female mammal, this, according to Prof. Allen Thomson3, is to be looked for in tissue uniting the urethra with the vagina. We might therefore be justified in expecting that in those animals in the female of which the lower ends of the Miillerian ducts unite to form the uterus and not the vagina, the prostate gland would be absent in the male. Such is certainly the case in H. crocuta; but that it would be erroneous to accept this as a general law is proved by a reference to the Elephant, in which, although the vagina is absent in the female, the male nevertheless possesses prostate glands of con- 1 Nova Acta Acad. Caes. Leop.-Oar. torn. xxii. p. 38. 2 ' Cyclopaedia of Anatomy,' vol. iv., Art, "Vesicula prostatica,'" 3 Quain's ' Anatomy.' 8th edit, vol. ii. p. 826. |