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 326 EMBRYOLOGY OF INSECTS AND MYRIAPODS The separation does not take place along the entire margin of the lateral plates simultaneously but occurs first at the cephalic end of the egg as a cap-like fold which grows rapidly caudad. A similar but slighter fold is later formed at the caudal end of the egg. The two folds eventually meet and coalesce near the caudal pole of the egg. At first
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 326 EMBRYOLOGY OF INSECTS AND MYRIAPODS The separation does not take place along the entire margin of the lateral plates simultaneously but occurs first at the cephalic end of the egg as a cap-like fold which grows rapidly caudad. A similar but slighter fold is later formed at the caudal end of the egg. The two folds eventually meet and coalesce near the caudal pole of the egg. At first the serosa consists of the dorsal part of the blastoderm except for the median longitudinal strip, but by the widening of the serosal bands the cells of their inner margins creep up over the dorsal strip, and the latter becomes submerged in the yolk (Fig. 280). Subsequently there is a fusion of the serosal bands along the dorsal mid-line of the egg, beginning first at the cephalic end. While the serosa is thus covering the dorsal side of the yolk, it starts also to cover the ventral side. The serosa together with the anterior end of the germ band then separates from the yolk. Soon afterward it separates from the yolk over the entire cephalic pole of the egg, rising up in the shape of a hemi- spherical cap. Next it severs its connection with the germ band around the anterior end of the latter and slides over it in the form of a hood, thus forming the cephalic fold (Fig. ). This separation of the serosa from the germ band progresses caudad along its lateral margins, accompanied by the caudal extension of the cephalic fold over the ventral face of the germ band. When the cephalic fold has covered about one-half the ventral face of the embryo, a caudal serosal fold (Fig. 283B) formed like the head fold appears at the extreme caudal end of the germ band. The two folds now approach each other until they finally meet and fuse at the caudal end (Fig. 283C). At this time the seros
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