File:On the anatomy of vertebrates (electronic resource) (1866) (14564329540).jpg

Identifier: b20416039_003 (find matches)
Title: On the anatomy of vertebrates (electronic resource)
Year: 1866 (1860s)
Authors: Owen, Richard, 1804-1892
Subjects: Anatomy, Comparative Vertebrates Fishes Reptiles Mammals Birds
Publisher: London : Longmans, Green
Contributing Library: Wellcome Library
Digitizing Sponsor: Wellcome Library

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ith coagulated blood, were found to unite; thecommon trunk then passed backward beneath the duodenum, andafter being joined by the mesenteric vein, went to the undersurface of the liver, where it penetrated that viscus : this was con-sequently an omphalo-mesenteric or vitelline vein. The arterywas a branch of the mesenteric. The membrane, therefore, uponwhich they ramified answered to the vitellicle, i. e. the vascularand mucous layers of the germinal membrane, which spreadsover the yolk in oviparous animals, and Avhich constitutes theso called 6 umbilical vesicle of the embryo of placental Mam-malia. The filamentary pedicle which connected this membraneto the intestine was given off near the end of the ileum. 720 ANATOMY OF VERTEBRATES. At a later period of uterine development, when the foetus,measured in a straight line from the mouth to the root of thetail, is ten lines in length, the urachus expands into a smallallantois, fig. 569, d, of a flattened pyriform figure, and finely 569
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Uterine foetus, membranes and appendages, Macr<,pus major. (The foetus is magnified twice the natural size.) wrinkled external surface. This bag insinuates itself betweenthe amnios and chorion, carrying along with it two small hypo-gastric arteries and a vein, but not establishing by their means anorganised and vascular surface of the chorion by which a placentalattachment is formed between the ovum and the womb. The DEVELOPMENT OF MARSUPIALIA. 721 allantois depends freely from the end of the umbilical cord, andhas no connection at any part of its circumference with theadjoining membrane. Its office, as in the Batrachia, is apparentlylimited to that of a receptacle of urine. The vitellicle or um-bilical vesicle presented the same large proportionate size andvascular structure as in the first described foetus. The chorionwhich enveloped this foetus and its appended sacs was adapted tothe cavity of the uterus by being disposed in innumerable foldsand wrinkles. It did not adhere at an

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