. The cell in development and inheritance. Cells. MORPHOLOGICAL COMPOSITION OF THE NUCLEUS 297 long afterward. Attention may be again called to the surprising case of Artemia, described at page 281, which gives a strong argument in favour of the hypothesis. In addition to the foregoing evidence, Van Beneden and Boveri were able to demonstrate in Ascaris that in the formation of the spireme the chromosomes reappear in the same position as those which entered into the formation of the reticulum, precisely as Rabl. Fig. 145. — Evidence of the individuality of the chromosomes in the egg of Ascaris
. The cell in development and inheritance. Cells. MORPHOLOGICAL COMPOSITION OF THE NUCLEUS 297 long afterward. Attention may be again called to the surprising case of Artemia, described at page 281, which gives a strong argument in favour of the hypothesis. In addition to the foregoing evidence, Van Beneden and Boveri were able to demonstrate in Ascaris that in the formation of the spireme the chromosomes reappear in the same position as those which entered into the formation of the reticulum, precisely as Rabl. Fig. 145. — Evidence of the individuality of the chromosomes in the egg of Ascaris. [BOVERI.] E. Anaphase of the first cleavage. F. Two-cell stage with lobed nuclei, the lobes formed by the ends of the chromosomes. G. Early prophase of the ensuing division ; chromosomes re-form- ing, centrosomes dividing. H. Later prophase, the chromosomes lying with their ends in the same position as before; centrosomes divided. maintained. As the long chromosomes diverge, their free ends are always turned toward the middle plane (Fig. 31), and upon the re- construction of the daughter-nuclei these ends give rise to correspond- ing lobes of the nucleus, as in Fig. 145, which persist throughout the resting state. At the succeeding division the chromosomes reappear exactly in the same position, tJieir ends lying in the nuclear lobes as before {¥\g. 145, G, H). On the strength of these facts Boveri con- cluded that the chromosomes must be regarded as " individuals " or " elementary organisms," that have an independent existence in the. 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
