. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. ORTHOPTEROIDEA (PANORTHOPTERA) 219 derm appears late, after the segmentation of the germ band. Yolk cells take no part in its formation. Blastokinesis is accomplished as described and figured for the dragonfly; amnion and serosa fuse into a single mem- brane at one point, only to tear open over the ventral side of the embryo, the edges of these two envelopes fused, both retracting dorsally, later to form th
. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. ORTHOPTEROIDEA (PANORTHOPTERA) 219 derm appears late, after the segmentation of the germ band. Yolk cells take no part in its formation. Blastokinesis is accomplished as described and figured for the dragonfly; amnion and serosa fuse into a single mem- brane at one point, only to tear open over the ventral side of the embryo, the edges of these two envelopes fused, both retracting dorsally, later to form the secondary dorsal organ at the back of the head. The yolk is now contained in a sack whose ventral wall is the embryo and whose lateral and dorsal walls are formed of the amnion and serosa. The head of the embryo now slips up along the ventral surface of the yolk to the anterior end of the egg, while the caudal end comes to lie beneath the micropyles of the opposite end. Finally the j^olk together with the enve- lopes is carried into the mid-gut, the dorsal wall closing over them. The development of organs is not described by Knower. PHASMATARIA The Walking Stick (Carausius morosus Br.) The developmental history of the walk- ing stick has been briefly described by several workers and more extensively by Hammerschmidt (1910), Thomas (1936), Leuzinger, Wiesmann, and Lehmann (1926), the work of the three last-men- tioned authors being the most detailed. As might be expected the development resembles most closely in general features that of the locust. The eggs, which measure over 2 mm. in length, are ellipsoidal and flattened laterally, with is pushed off on emergence of the insect. a small number of cleavage nuclei may be found in the periplasm in the region not far from the posterior pole. These proliferate and give rise to further nuclei that migrate tangentially in the periplasm. They remain sparsely scattered over the surface except at the posterior end, where they form a sm
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