. A manual of zoology. Zoology. Fig. 540. Fig. 541. Fig. 540.—Shark embrj'O (from Boas), y, part of yolk sac; g. external gills in front of pectoral fins. Fig. 541.—Embrj'onic envelopes of chick (schematized, after Duval), a/, allan- tois; am, amnion; ait eye; c, extraembryonic ccelom; d, digestive tract; do, yolk sac; k, gill clefts; m, mid-brain; i, 2, hinder and anterior extremities. the whole emlsryo and is connected with the rest only at the umbilicns, that is, the point where the yolk sac projects from the ventral wall. In this sac is an albuminous amniotic Jhiid. The amnion is genetical
. A manual of zoology. Zoology. Fig. 540. Fig. 541. Fig. 540.—Shark embrj'O (from Boas), y, part of yolk sac; g. external gills in front of pectoral fins. Fig. 541.—Embrj'onic envelopes of chick (schematized, after Duval), a/, allan- tois; am, amnion; ait eye; c, extraembryonic ccelom; d, digestive tract; do, yolk sac; k, gill clefts; m, mid-brain; i, 2, hinder and anterior extremities. the whole emlsryo and is connected with the rest only at the umbilicns, that is, the point where the yolk sac projects from the ventral wall. In this sac is an albuminous amniotic Jhiid. The amnion is genetically a part of the ventral surface; it develops ventrally as a circular fold—lateral, anterior, and posterior—which grows up over the back on all sides and unites above the embryo. The allajitois (al) is an enlargement of the urinary bladder. This grows out from the Ijody cavity at the umbilicus and extends between yolk sac and amnion and then grows in all directions until its folds meet aljove the back carrying with it blood-vessels and connective tissue. The blood-vessels are the most important, for the allantois forms the respiratory. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929, ed. and tr. New York, H. Holt
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
