. The cell in development and inheritance. Cells. MATURATIOX OF PARTFIEXOGENETIC EGGS 283 two daughter-groups, each containing eighty-four single chromosomes. Both these groups reviain in the egg, and each gives rise to a single reticular nucleus, as described by Boveri in As-caris. These tzvo nuclei place themselves side by side in the cleavage-figure, and give rise each to eigJity-four chroniosonies. precisely like tzvo germ-nuclei in ordinary fertilization. The one hundred and sixty-eight chromosomes spHt. D E Fig. 142. — Second type of maturation in the parthenogenetic egg of Artemia. [Bra
. The cell in development and inheritance. Cells. MATURATIOX OF PARTFIEXOGENETIC EGGS 283 two daughter-groups, each containing eighty-four single chromosomes. Both these groups reviain in the egg, and each gives rise to a single reticular nucleus, as described by Boveri in As-caris. These tzvo nuclei place themselves side by side in the cleavage-figure, and give rise each to eigJity-four chroniosonies. precisely like tzvo germ-nuclei in ordinary fertilization. The one hundred and sixty-eight chromosomes spHt. D E Fig. 142. — Second type of maturation in the parthenogenetic egg of Artemia. [BraUER.] A. Formation of second polar body. B. Return of the second polar nucleus {p. d.^) into the egg; development of the egg-amphiaster. C. Union of the egg-nucleus (?) with the second polar nucleus (/. 6.^). D. Cleavage-nucleus and amphiaster. E. First cleavage-figure with equatorial plate containing 168 chromosomes in two groups of 84 each. lengthwise, and are distributed in the usual manner, and reappear in the same number in later stages. In other words, the second polar body here plays the part of a sperm-nucleus precisely as maintained by Boveri. In all individuals arising from eggs of the first type, therefore, the somatic number of chromosomes is eighty-four; in all those arising from eggs of the second type, it is one hundred and sixty-eight. This. 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 Wilson, Edmund B. (Edmund Beecher), 1856-1939. New York, Macmillan
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectcells, bookyear1911
