. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. ECTODERMAL DERIVATIVES 105 divided into three pairs of lobes (Fig. 47, lob), the most lateral being the optic lobes (). In the two median pairs of lobes the neuroblasts (neur) have the typical form of those found in the ventral nerve cords, the daughter cells (gglc) forming the usual ganglion cells whose interlacing fibers represent the neuropile. The neuroblasts degenerate after the formation of the d
. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. ECTODERMAL DERIVATIVES 105 divided into three pairs of lobes (Fig. 47, lob), the most lateral being the optic lobes (). In the two median pairs of lobes the neuroblasts (neur) have the typical form of those found in the ventral nerve cords, the daughter cells (gglc) forming the usual ganglion cells whose interlacing fibers represent the neuropile. The neuroblasts degenerate after the formation of the daughter cells. Before the optic lobe is fully differ- lob I. Fig. 48.—Mantis rdigiosa. Cross section of head through developing eye. A-C, successive stages, (am) Amnion, {ect) Ectoderm, {ed. d) Dermatogene cells, {ect. ggl) Gangliogene cells, {eye) Eye plate (disk), {loh) First, second, and third protocerebral lobes, {mes) Mesoderm. {From Vicdlanes.) entiated and is still a part of the epidermis, the region may be dis- tinguished by its rather large cells. Although it is generally conceded that no neuroblasts take part in the formation of optic lobes in insects, these larger cells in Mantis are termed "gangliogenes" (, neuroblasts) by Viallanes (1891). Heymons, in his account of the development of Forficula, states that they correspond to neuroblasts, not that they are neuroblasts. The development of compound eyes in the paurometabolous insects is brought about by the formation of an eye disk (eye) in the ectodermal. 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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