. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. CHAPTER XXI MYRIAPODA CHILOPODA, THE CENTIPEDES Scolopendra cingulata and dalmatica The Egg Cleavage and Blastoderm Formation.—The eggs of these two European centipedes are laid during June in the earth at a depth of 3 to 8 cm. in clumps of 15 to 20 or more, the female remaining curled around the mass until the young begin feeding. The short ovoid egg averages 3 mm. in length and has a thin but brittle chor
. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. CHAPTER XXI MYRIAPODA CHILOPODA, THE CENTIPEDES Scolopendra cingulata and dalmatica The Egg Cleavage and Blastoderm Formation.—The eggs of these two European centipedes are laid during June in the earth at a depth of 3 to 8 cm. in clumps of 15 to 20 or more, the female remaining curled around the mass until the young begin feeding. The short ovoid egg averages 3 mm. in length and has a thin but brittle chorion. Although the egg. Fig. 337.—Scolopendra. Median section after intravitelline differentiation of the cleavage cells, (ic) Intercalary cells. {,cc) Cleavage cells. {Adapted from Heymons.) contains a protoplasmic reticulum, the meshes of which contain the food yolk, a periplasm is apparently lacking. Shortly after fertilization some cleavage nuclei surrounded by a layer of cytoplasm appear in the yolk. Meanwhile the egg yolk undergoes a pyramidal cleavage (Fig. 337) with the polygonal bases at the egg surface (Fig. 338). A few cleavage cells which Heymons (1901) designates as intercalary cells (i. c) are found on the bounding surfaces of the yolk pyramids, and in the central part of the egg are a number of cleavage cells designated as "pyramid cells" (Fig. 337, c. c). The intercalary cells mitotically divide and migrate toward the periphery, where further cell division takes place, the blastoderm thus arising from isolated cell groups that have developed from the outward 382. 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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