Embryology of insects and myriapods; Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching embryologyofinse00joha Year: 1941 SIPHON APTERA AND DIPT ERA 377 writers confused the amniotic cavity with the proctodaeum, giving rise to erroneous interpretations. As development continues, the caudal end pushes still farther forward; the proctodaeum deepens; and from near its extremity, dorsal and ventral diverticula, the beginnings of the Mal- pighian tubules, appear. The posterior mesenteron rudiment is closely fus
Embryology of insects and myriapods; Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching embryologyofinse00joha Year: 1941 SIPHON APTERA AND DIPT ERA 377 writers confused the amniotic cavity with the proctodaeum, giving rise to erroneous interpretations. As development continues, the caudal end pushes still farther forward; the proctodaeum deepens; and from near its extremity, dorsal and ventral diverticula, the beginnings of the Mal- pighian tubules, appear. The posterior mesenteron rudiment is closely fused with the apex of the proctodaeum. At this time the head and tail end of the embryo lie rather close together, a condition that, however, does not last long (Fig. 331^). Then the shortening of the embryo proct Fig. 332.—Calliphora erythrocephala. Sagittal sections of two stages, A and B. (ect) Ectoderm, (ent) Entoderm, (ggl) Nerve ganglion, (malp) Rudiment of Malpighian tubule, {mes) Mesoderm, {proct) Proctodaeum. (stom) Stomodaeum. (y) Yolk. begins and continues until the anal end again lies at the posterior end of the egg (Figs. 332^,B). When the germ band has reached its greatest length, the transverse amniotic invagination marks the caudal extremity as seen from the dorsal surface (Fig. 333). At this time the vestiges of six pairs of stigmatal ectodermic invaginations are also in evidence, the first stigmata appar- ently belonging to the mesothorax. Anteriorly in dorsal aspect the two head lobes are visible. At this stage distinct segmentation may be seen on the ventral side. The salivary glands according to Graber (1889) first show as paired ectodermal invaginations between the third and fourth head segments or
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