. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. 200 EMBRYOLOGY OF INSECTS AND MYRIAPODS. stom ^^C -> m 'â rCt? ry IM. â¢ysp s'^4v.) ^ that they had while in the egg. The labium at this time is long and slender and lies extended back on the ventral side under the thorax and abdomen. For a short time after emergence the nymph lies quietly on its side or back, but soon the embryonic integument breaks and the nymph emerges. When it is free, the tip
. Embryology of insects and myriapods; the developmental history of insects, centipedes, and millepedes from egg desposition [!] to hatching. Embryology -- Insects; Embryology -- Myriapoda. 200 EMBRYOLOGY OF INSECTS AND MYRIAPODS. stom ^^C -> m 'â rCt? ry IM. â¢ysp s'^4v.) ^ that they had while in the egg. The labium at this time is long and slender and lies extended back on the ventral side under the thorax and abdomen. For a short time after emergence the nymph lies quietly on its side or back, but soon the embryonic integument breaks and the nymph emerges. When it is free, the tip of the labium assumes a position in front of the head like a mask. Although the time varies between hatch- ing and completion of the first molt, the whole procedure takes less than ten minutes. Immediately after hatching, the tubular mid- gut extends to the second or third segment of the abdomen (Fig. 125). Soon after the nymph is free of the embryonic exuviae, the mid-gut shortens by nearly one-half its previous length (Fig. 126). For the first day or two, and occasionally for as much as three days, the larva does not take food. Even after the larva first begins feeding, it is apparent that the digestive epithehum has not yet formed. The mid-gut still contains in its walls vacuolate tissue charac- teristic of the embryonic stages, the food being stored in the posterior end of the fore-gut. Tschuproff, working with Epitheca bimaculata and Libellula quadrimaculata, stated that the anterior and posterior thirds of the mid-gut are formed from ectoderm cells which grow out cup- like around the yolk from the stomodaeal and proctodaeal invaginations. The middle section, on the other hand, is formed from entodermal cells within the yolk. These cells migrate to the periphery of the mid-gut where they form re- generative cell masses lying in crypts adjacent to the muscle layer and between the yolk compartments. When the mid- intestine first forms in Plathemis, the whole wall is made
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