File:Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct - for the use of schools and colleges (1870) (14596169239).jpg

Identifier: outlinesofcompar00agas (find matches)
Title: Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges
Year: 1870 (1870s)
Authors: Agassiz, Louis, 1807-1873 Gould, Augustus A. (Augustus Addison), 1805-1866 Wright, Thomas, 1809-1884
Subjects: Physiology, Comparative Zoology
Publisher: London : Bell & Daldy
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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open abdomen; 0, anterior part of the head(corpora quadrigemina) ; p, hemispheres ; r, superior maxilla; s, inferiormaxilla ; I, oral cleft or aperture ; 1, 2, 3, three branchial clefts. Otherreferences as in fig. 338. DEVELOPMENT OF THE CHICK SECOND PEEIOD. 315 the anterior is now called the vagina capitis; the posterior va-gina caudcB (fig. 343, B, f, backwards); the lateral folds may,in like manner, be entitled the vaginae later ales (fig. 343, A,/, /) ; they coalesce at the end of the fourth day, and form avisible cicatrice over the lumbar region of the embryo. In thisway we have a complete vesicular envelope thrown around theembryo,—the AMFION (fig. 344, a, a), which is filled withfluid. The upper layer of the fold (fig. 343, A and B, lyingunder the vitelline membrane, a\ covers the whole germinalmembrane, and grows around the yolk as a serous capsule orcyst, vesica serosa—the false amnion of Pander. At the placewhere the embryo lies, this layer is separated from the rest of
Text Appearing After Image:
Fig. 344.—Outline of the embryo of the fowl, at the end of the fifthday, much magnified; a, a, amnion ; 6, allantois; c, corpora quadrige-mina; d, hemispheres ; e, eye ; /, anterior ; and g, posterior extremity.The natural dimensions of this, as of many of the other figures, are indi-cated by a line, or lines, with an asterisk. 316 EMBRYOLOGY. the germinal membrane by a considerable space. The inferiorlayer of the serous ventral lamina forms the ventral paries, andgives origin to the bones and muscles which compose the neckand trunk. Inferiorly, the vascular lamina lies upon it, andthis, with the serous lamina, evolves the formations which arenow to be described. On either side, under the vertebralcolumn, there is a lamina detached, which grows thicker, andincreases in a direction perpendicularly downwards ; these arethe lamina mesenteries, between which there is, at first, anopen triangular-shaped channel or cleft, the foramen mesen-terii; both the mesenteric laminae push the mucou

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