. A manual of zoology. Zoology. Fig 106.—Superficial cleavage of an insect egg, Pier is cralirgi (after Bobretzky). A, division of the cleavage nucleus; 5, movement of the nuclei to the periphery to form the blastoderm; C, formation of the blastoderm. and form the blastoderm; hence the name for this stage, blastodermic vesicle, or blastula. The more yolk present, the smaller is the cleavage cavity; in eggs with superficial cleavage it is entirely absent. 4. Formation of the Germ-layers. Gastrula.—Besides the blastula there is a second stage of development, the gastrula or the two-layered embry
. A manual of zoology. Zoology. Fig 106.—Superficial cleavage of an insect egg, Pier is cralirgi (after Bobretzky). A, division of the cleavage nucleus; 5, movement of the nuclei to the periphery to form the blastoderm; C, formation of the blastoderm. and form the blastoderm; hence the name for this stage, blastodermic vesicle, or blastula. The more yolk present, the smaller is the cleavage cavity; in eggs with superficial cleavage it is entirely absent. 4. Formation of the Germ-layers. Gastrula.—Besides the blastula there is a second stage of development, the gastrula or the two-layered embryo, common to all the Metazoa. This stage is understood easiest in eggs which have an equal cleavage (fig. 107, B); here it has the form of a double-walled cup with a wider or 10. 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929, ed. and tr. New York, H. Holt
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
