Text-book of comparative anatomy . ssStV- B FIG. 61.—Sections of three stages of development of Oscarella lobularis, after K. , Gastrula which has attached itself. B, Rudiments of mesoderm and canal system. (., Forma-tion of the osculum and ciliated chambers, e, Ectoderm ; en, endoderm ; m, mesoderm ; o, osculum ;P, pores ; wk, ciliated chambers. that it is hardly possible to form a generally applicable scheme. AVe select thenewly investigated development of Oscarella (Halisarca) lobularis (Fig. 61). By means of repeated egg division a freely swimming larva arises, the Blastula. This i

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Text-book of comparative anatomy . ssStV- B FIG. 61.—Sections of three stages of development of Oscarella lobularis, after K. , Gastrula which has attached itself. B, Rudiments of mesoderm and canal system. (., Forma-tion of the osculum and ciliated chambers, e, Ectoderm ; en, endoderm ; m, mesoderm ; o, osculum ;P, pores ; wk, ciliated chambers. that it is hardly possible to form a generally applicable scheme. AVe select thenewly investigated development of Oscarella (Halisarca) lobularis (Fig. 61). By means of repeated egg division a freely swimming larva arises, the Blastula. This is a hollow sphere, whose wall consists of one single layer of flagellate cell-. The blastula by imagination becomes a gastrula. This attaches itself by the gastrula mouth or blastopore, and the aperture gradually narrows and finally closes. VOL. I F 66 COMPARATIVE ANATOMY CHAP. Gelatinous substance is secreted between the ectoderm and endoderm, and intothis cells migrate most probably from the endoderm. Thus the connective tissu

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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative