Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote elementarytextbo01clau Year: 1892-1893 FIG. 104.—Unequal segmentation of the Frog's tgg (after Eckeij in ten succe^ve stages. and larger portion, in which the segmentation proceeds much more slowly than in the former. In partial segmentation we find a sharply marked contrast between the formative and nutritive parts of the egg, inasmuch as the latter does not seg- ment. The terms holoUastie and mz- roblastiG therefore have been applied to total and partial seg- mentation respec- tively. Neve
Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote elementarytextbo01clau Year: 1892-1893 FIG. 104.—Unequal segmentation of the Frog's tgg (after Eckeij in ten succe^ve stages. and larger portion, in which the segmentation proceeds much more slowly than in the former. In partial segmentation we find a sharply marked contrast between the formative and nutritive parts of the egg, inasmuch as the latter does not seg- ment. The terms holoUastie and mz- roblastiG therefore have been applied to total and partial seg- mentation respec- tively. Nevertheless, in total segmentation also, either groups of segments of a definite quality, or, at any rate, a fluid yolk material may be Used FIG. 105. Segmentation of the germinal di&c of a Fc vd's egg, for the nourishment ^face view (after Koaiker)'. ^germinal disc with the first vertical furrow ; B, the same with two vertical furrows of the developing crossing one another at right angles ; C and L>, more ad- embryo. In fact, the vanced stagos with 8ma11 ceutral sesmeuts- contents of every egg consists of two parts—(1) of a viscous albu- minous protoplasm; and (2) of a fatty granular matter, the deutoplasm, or food yolk. The first is derived from the protoplasm
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