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 anir Fig. 227.—Siylops nycthemerae. (am) Amnion, {antr) Anterior, (post) Poste- rior end. (vent) Venter, (y) Yolk. anir •posi .am Fig. 228.—Stylops. {am) Amnion. {antr) Anterior end. {i. am) Inner and (o. am) outer section of amnion, {par) Paracyte. {post) Posterior end. These are interpreted by Noskiewiez and Poluszynski as either symbionts or, more probably, paracytes. Further prol
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 anir Fig. 227.—Siylops nycthemerae. (am) Amnion, {antr) Anterior, (post) Poste- rior end. (vent) Venter, (y) Yolk. anir •posi .am Fig. 228.—Stylops. {am) Amnion. {antr) Anterior end. {i. am) Inner and (o. am) outer section of amnion, {par) Paracyte. {post) Posterior end. These are interpreted by Noskiewiez and Poluszynski as either symbionts or, more probably, paracytes. Further proliferation of the cells of the embryo produces an ingrowth of the caudal end whereby apparently a pressure is exerted on the yolk. In Fig. 227 the yolk is shown partly divided, a small one- or two-nucleated portion at the center, a larger portion at the surface (Fig. 227, y). In the development of viviparous or parasitic insects Noskiewiez and Poluszynski (1927) say that if the yolk has preserved its primary ento- dermal potentiality, it will not degenerate before it has served its function in relation to the development of the mid-gut epithelium, even though it may have been considerably reduced in size. If, however, the potential- ity has been lost, one of two things may happen: either it degenerates quickly and completely, or it will be used in the formation of a secondary envelope. For example, in Stylops and Halictoxenus a small part of the yolk aids in the formation of the mid-gut epithelium; on the other hand, the larger part of the yolk in the former insect degenerates; in the latter it contributes to the formation of the trophamnion-like envelope.
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