. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. Fig 175—Pediculus Sagittal section. Fig. 176.—Pediculus. Sagittal sec- (gb) Germ band, {myct) Mycetam. {aer) tion. (am) Amnion. (ect) Ectoderm. Serosa. igb) Germ band, (mes) Mesoderm. {myct) Mycetom. {ser) Serosa. then separates from the serosa. The mycetom now lies wholly free in the yolk (Fig. 177, myct) under the micropyle. At the time of invagina- tion of the germ band, the cleavage of the yolk into sph
. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. Fig 175—Pediculus Sagittal section. Fig. 176.—Pediculus. Sagittal sec- (gb) Germ band, {myct) Mycetam. {aer) tion. (am) Amnion. (ect) Ectoderm. Serosa. igb) Germ band, (mes) Mesoderm. {myct) Mycetom. {ser) Serosa. then separates from the serosa. The mycetom now lies wholly free in the yolk (Fig. 177, myct) under the micropyle. At the time of invagina- tion of the germ band, the cleavage of the yolk into spherules begins, first at the posterior pole, then at the anterior pole, and finally in the center. Vitellophags within the spherules reduce the yolk to a homogeneous mass. When the germ band has become flexed (Fig. 176), the inner layer begins to develop on its dorsal, or yolk, side in the form of isolated cell islands along the median hne. These cell islands enlarge and finally fuse into an inner layer which represents the entoderm and mesoderm. While the inner layer is forming, first the proctodaeum (Fig. 177) and then the stomodaeum make their appearance. The anterior and pos- terior mesenteron rudiments are derived from the inner layer (Fig. 180).. 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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