. Principles of human physiology : with their chief applications to pathology, hygiene, and forensic medicine : especially designed for the use of students. olffian bodies; and they graduallyincrease, the temporary organs diminishing inthe same proportion. The sexual organs, aswill be hereafter explained (§ 699), also originatein the Wolffian bodies; and at the end of foetallife, the only vestige of the latter is to be foundas a shrunk rudiment situated near the testes ofthe male. The progress of development in theHuman embryo seems closely conformable tothe foregoing account. The Wolffian bod
. Principles of human physiology : with their chief applications to pathology, hygiene, and forensic medicine : especially designed for the use of students. olffian bodies; and they graduallyincrease, the temporary organs diminishing inthe same proportion. The sexual organs, aswill be hereafter explained (§ 699), also originatein the Wolffian bodies; and at the end of foetallife, the only vestige of the latter is to be foundas a shrunk rudiment situated near the testes ofthe male. The progress of development in theHuman embryo seems closely conformable tothe foregoing account. The Wolffian bodiesbegin to appear towards the end of the firstmonth; and it is in the course of the seventhweek that the true kidneys first present them-selves. From the beginning of the third month,the diminution in the size of the Wolffian bodiesgoes on pari passu with the increase of the kid-neys; and at the time of birth scarcely any tracesof them can be found. At the end of the thirdmonth, the kidneys consist of seven or eightlobes, the future pyramids; their excretory ductsstill terminate in the same canal which receives those of the Wolffian bodies Fig. Corpora Wolffiana, with kidneyand testes, from embryo of Birds;«; kidney; b, b, ureters; c, corpusWolffianum; d, its excretory duct;e, e, testicles; at the summit areseen the supra-renal capsules. * See Principles of General and Comparative Physiology, § 659. 518 OF SECRETION. and of the sexual organs; and this opens, with the rectum, into a sort ofcloaca, or sinus urogenitalis, analogous to that which is permanent in theoviparous Vertebrata. The kidneys are at this time covered by the supra-renal capsules, which are very large; about the sixth month, however, thesehave decreased, whilst the kidneys have increased, so that their propor-tional weight is as 1 +o 2§. At birth, the weight of the kidneys is aboutthree times that of the supra-renal capsules, and they bear to the wholebody the proportion of 1 to 80: in the adult, howe
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