. A manual of zoology. Zoology. Fig. ;uperhcial cleavage of an inaeot egg (Picris crat ryi) ( After I tjietzk-\ ) .1, division of the cleavage nucleus ; JB, movement of the nuclei t) the t trii htrv to form the blastoderm; C, formation of the blastoderm. cuttlefishes, while the equal and the unequal cleavage can be found in all the groujis of the Metazoa. Blastula.—Sometimes during the first stages of segmentation, sometimes later, there is usually formed a cavity, the cleavage or segmentation caoUy, between the cells in the interior of the ego-; with the progress of development this
. A manual of zoology. Zoology. Fig. ;uperhcial cleavage of an inaeot egg (Picris crat ryi) ( After I tjietzk-\ ) .1, division of the cleavage nucleus ; JB, movement of the nuclei t) the t trii htrv to form the blastoderm; C, formation of the blastoderm. cuttlefishes, while the equal and the unequal cleavage can be found in all the groujis of the Metazoa. Blastula.—Sometimes during the first stages of segmentation, sometimes later, there is usually formed a cavity, the cleavage or segmentation caoUy, between the cells in the interior of the ego-; with the progress of development this cavity becomes continually larger (fig. 100, B). Around it the cells lie in the form of a one- layered or of a many-layered epithelium and form the blastoderm; hence the name for this stage, Uastodennic vesicle, or, bncflv, Uastula. The more yolk there is present, the smaller is the cleavage cavity; in centrolecithal eggs with superficial cleavage it is entirely 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. New York, H. Holt and Company
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
