. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. EPHEMERIDA, O DON AT A, PLECOPTERA, ET AL. 195 invagination of the embryo in this species (Fig. 117) produces a pit in the yolk mass, one wall of which is the embryo itself (gb); the other wall on the dorsal side of the egg, the amnion {am). Before the head of Calopteryx withdraws completely, segmentation begins, and appendages appear (Fig. USA). As the embryo lengthens, the caudal end doubles on itself, fo
. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. EPHEMERIDA, O DON AT A, PLECOPTERA, ET AL. 195 invagination of the embryo in this species (Fig. 117) produces a pit in the yolk mass, one wall of which is the embryo itself (gb); the other wall on the dorsal side of the egg, the amnion {am). Before the head of Calopteryx withdraws completely, segmentation begins, and appendages appear (Fig. USA). As the embryo lengthens, the caudal end doubles on itself, forming a hook (Fig. 117(7). The tail folds under the abdomen (Fig. USA) and maintains this position even after the embryo withdraws from the yolk. When the axis of the head is finally shifted, the opening behind it is closed by the serosa (Fig. 1185). The amnion in the head region now forms a large sac, part of which lies in contact with the serosa. Just. am. 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 Johannsen, O. A. (Oskar Augustus), 1870-1961; Butt, Ferdinand Hinckley, 1899-. New York, London, McGraw-Hill Book Company, inc.
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