Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges . he vessels of the allantois are developed with great vigour ;two arteries arise from the aorta, and a large vein runs onthe under edge of the liver to the vena cav^, along with the DEVELOPMENT Of THE CHICK—THIRD PEKIOD. 329 hepatic vein. The vessels of the ailantois become the umbi-lical vessels. The alterations that trans-pire in the mucous layer areof less moment: the or-gans already formed in creasein size ; the faucial cavity is m elo
Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges . he vessels of the allantois are developed with great vigour ;two arteries arise from the aorta, and a large vein runs onthe under edge of the liver to the vena cav^, along with the DEVELOPMENT Of THE CHICK—THIRD PEKIOD. 329 hepatic vein. The vessels of the ailantois become the umbi-lical vessels. The alterations that trans-pire in the mucous layer areof less moment: the or-gans already formed in creasein size ; the faucial cavity is m elongated as the oral cavityin the bill-shaped maxillae ;the esophagus extends; thedivision into crop and mus-cular stomach is distin-guishable ; behind the loopfor the duodenum,andwhich 1 ,1 ,-1 Ai&« Ui»j.—rxn ciiiijivu ounicv> licit encloses the pancreas, the ()lderethan that represented in fig. 349,jejunum forms a noose of surrounded by the amnion as an am-ple vesicle ; a, the amnion; the eyes,b, b, are very large ; c, c, the corporaquadrigemina, now scarcely larger thanthe hemispheres d. d; the space be-tween them is the third Fig. 353.—An embryo somewhat the same length and tenui-ty, which lies completelyout of the abdomen withinthe umbilical cord, where,bv means of a delicate short tt conduit, it communicates with the vitellicle or yolk-sac,—theductus mtello-intestinalis (fig. 352, A, «). The liver is largeand gorged with blood; the trachea and lungs are entirelyseparated from the esophagus ; the larynx makes its appear-ance as a small enlargement upon the trachea. [§ 495. The principal changes from the ninth to the eleventhday are as follow : the hemispheres of the brain enlargegreatly, at the cost, apparently, of the corpora quadrigemina,and span the third ventricle posteriorly ; the cerebellum in-creases, particularly in its middle or vermiform portion, by whichthe fourth ventricle isnow completely hidden; in the spinal cordthe enlargements corr
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectzoology, bookyear1870
