Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges . nspicuous, and the corresponding oviduct is hollow,whilst the same parts on the right side have shrunk entirely. DEYELOPMEirT OF THE CHICK—THIED PERIOD. 331 The intestine makes several turns outside of the umbilicus,and continues in communication with the vitellary sac bymeans of the vitellary duct; upon the inner surface of thevitellary sac, and over the tortuous veins, membranous pro-ductions—puckered or wrinkled folds—make their appear
Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges . nspicuous, and the corresponding oviduct is hollow,whilst the same parts on the right side have shrunk entirely. DEYELOPMEirT OF THE CHICK—THIED PERIOD. 331 The intestine makes several turns outside of the umbilicus,and continues in communication with the vitellary sac bymeans of the vitellary duct; upon the inner surface of thevitellary sac, and over the tortuous veins, membranous pro-ductions—puckered or wrinkled folds—make their appear-ance ; and at the same time similar formations occur upon themucous membrane of the intestine. The allantois has nowgrown completely around the embryo, so that the ovum—thevitellary sac, the remaining albumen, &c. included—is com-pletely enve-loped anew asit were,and willnow retain itsform even afterthe shell is re-moved (, b; from theKestril—Falcotinnunculus) ;the serous co-vering disap-pears. [§ 497. Inthe beginningof the thirdweek, the em-bryo, straitenedfor room, fromthe transverseaxis of the eggcomes more andmore into the. Fig. 354.—Embryo of the Falco tinnuncnlns,much farther advanced than that of the fig. 353. Jtis represented enclosed in its membranes, and of thenatural size ; but heing removed from the shell, itsweight has caused it to spread, and to look longerthan it is in fact. The embryo of this falcon, byreason of the transparency of the membranes, is pe-culiarly fitted to serve for the demonstration of thelong axis, which, relative position of the several parts: a, the embryoit finally fills ; shining through the membranes ; /, /, the eyes of great size, seen from above; b, b, the ailantois, hasgrown completely around the embryo, and so formsa perfect envelope, the chorion, whose principal vas-cular branches are perceived ; c, c, the amnion ; d. d, the head isturned towardsthe breast, and _ , . «J A «-VA « \_ ti v^ u u,.a »_> W
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectzoology, bookyear1870
