. Biological lectures delivered at the Marine Biological Laboratory of Wood's Holl [sic]. Biology. Fig. 12. • Fig. 9. —Arenicola. Somatic plate consists of three cells which have arisen by spiral divisions. Fig. 10. —Arenicola. Somatic plate after spiral divisions have ceased. Fig. II. —Are7iicola. Somatic plate. The cell dp gives rise to the two dorsal cells of the para- troch, the cell xl \.o the two lateral paratroch cells of the left side. Fig. 12. — Arenicola. Somatic plate. The cell a^ dividing spirally. the axes of symmetry are the same as in the adult {cf. Fig. 5 with Figs. 7 and

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. Biological lectures delivered at the Marine Biological Laboratory of Wood's Holl [sic]. Biology. Fig. 12. • Fig. 9. —Arenicola. Somatic plate consists of three cells which have arisen by spiral divisions. Fig. 10. —Arenicola. Somatic plate after spiral divisions have ceased. Fig. II. —Are7iicola. Somatic plate. The cell dp gives rise to the two dorsal cells of the para- troch, the cell xl \.o the two lateral paratroch cells of the left side. Fig. 12. — Arenicola. Somatic plate. The cell a^ dividing spirally. the axes of symmetry are the same as in the adult {cf. Fig. 5 with Figs. 7 and 8, also Fig. 9 with Fig. 10). This bilateral type of cleavage is evidently connected with the process of morphogenesis, and I desire to call it, for convenience, a nioi'pJiogenetic cleavage. A morphogenetic form of cleavage. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ). Boston, Ginn & Co

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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectbiology