Entomology : with special reference to its biological and economic aspects . ^?i^^dm^c^ioocM^ Transverse section of germ layersand amnion folds of Clytra. a, am-nion; e, ectoderm; i, inner layer(meso-entoderm): .s, serosa.—Original,based on Lecaillons Transverse section of germ layers andembryonal membranes of Clytra. a, am-nion; ac, amnion cavity; e, ectoderm; i,inner layer (meso-entoderm); s, serosa.—After Lecaillon. layer, which is destined to form two layers, known respectivelyas entoderm and mesoderm. This formation of two primarygerm layers by invagination or otherwise is terme
Entomology : with special reference to its biological and economic aspects . ^?i^^dm^c^ioocM^ Transverse section of germ layersand amnion folds of Clytra. a, am-nion; e, ectoderm; i, inner layer(meso-entoderm): .s, serosa.—Original,based on Lecaillons Transverse section of germ layers andembryonal membranes of Clytra. a, am-nion; ac, amnion cavity; e, ectoderm; i,inner layer (meso-entoderm); s, serosa.—After Lecaillon. layer, which is destined to form two layers, known respectivelyas entoderm and mesoderm. This formation of two primarygerm layers by invagination or otherwise is termed gastrula-tion; it is an important stage in the development of all eggs,and among insects several variations of the process and Serosa.—^Meanwhile, the blastoderm has been DEVELOPMENT 149 folding over the germ band from either side, as shown in , and at length the two folds meet and unite to form twomembranes (Fig. 191), namely, an inner one. or aiimioii, andan outer one, or serosa. Fig. 192. SS^\ ,v>#fSi?^. %?? -Si 5; as. 11 II if ^ ^^ S5 .V: ;;,;:^.,v;,,\ ;/-:.^- ??^-^ if q^Rf Mi ^V>. i^ # i ^ »^1S fj^ VS WW v-*- 11 * - t^^ is { K-^*-^:^ sfr I ^? %^. E ; • £^-15^ V- jij w;; i-^ •^ * =S ^ ki ~K- 11 f oj- B fci
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectentomology, bookyear1
