General principles of zoology . »\Miw<f. FIG. 104.—Formation of the mesepithelium and of the coslom of Sagitta. A. From thebottom of the gastrula arise two folds, which divide the archenteron into the permanentdigestive tract and the coelomic diverticula. B. The separation is almost completed bythe pushing up of the folds, ak. outer, »ik, middle, ?/t, inner germ-layer ; tnk*, somato-pleure ; ink*, splanchnopleure ; //i, body-cavity. The mesepithelium is a part of the entoblast constrictedoff, the mode of development of which is shown in theembryology of the worm Sagitta (Fig. 104). GENERAL
General principles of zoology . »\Miw<f. FIG. 104.—Formation of the mesepithelium and of the coslom of Sagitta. A. From thebottom of the gastrula arise two folds, which divide the archenteron into the permanentdigestive tract and the coelomic diverticula. B. The separation is almost completed bythe pushing up of the folds, ak. outer, »ik, middle, ?/t, inner germ-layer ; tnk*, somato-pleure ; ink*, splanchnopleure ; //i, body-cavity. The mesepithelium is a part of the entoblast constrictedoff, the mode of development of which is shown in theembryology of the worm Sagitta (Fig. 104). GENERAL EMBRYOLOGY. Ccelomic Pouches.—When the gastrula of Sagitta hasbeen formed, there arise on the walls of the archenteronopposite the mouth two entoblastic folds, symmetrical withthe mid-line of the body, which divide the archenteroninto three cavities, at first still in communication—thepermanent digestive tract and the two rudiments of thebody-cavity, the coelomic diverticula. Then the blastoporecloses and the entoderm folds extend e
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1896
