. The cell in development and inheritance. Cells. ORIGIN OF THE GERM-CELLS 149 is less than in the somatic cells (Fig. 74). Vom Rath, working in the same direction, believes that in the salamander also the number of chromosomes in the early progenitors of the germ-cells is one-half that characteristic of the somatic cells.^ In both these cases, the chromosomes are doubtless bivalent, representing two. Fig. 74. — Primordial germ-cells in C)y7<7/j-. [Hackek.] A. Young embryo, showing stem-cell {st). B. The stem-cell has divided into two, giving rise to the primordial germ-ceil {g). C. Later s
. The cell in development and inheritance. Cells. ORIGIN OF THE GERM-CELLS 149 is less than in the somatic cells (Fig. 74). Vom Rath, working in the same direction, believes that in the salamander also the number of chromosomes in the early progenitors of the germ-cells is one-half that characteristic of the somatic cells.^ In both these cases, the chromosomes are doubtless bivalent, representing two. Fig. 74. — Primordial germ-cells in C)y7<7/j-. [Hackek.] A. Young embryo, showing stem-cell {st). B. The stem-cell has divided into two, giving rise to the primordial germ-ceil {g). C. Later stage, in section; the primordial germ-cell has migrated into the interior and divided into two ; two groups of chromosomes in each. chromosomes joined together. In Ascaris, in like manner, each of the two chromosomes of the stem-cell or primordial germ-cells is probably plurivalent, and represents a combination o': several units of a lower order which separate during the segmentation of the thread when the somatic mitosis occurs. 1 Cf. p. 256, Chapter 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, bookdecade1900, booksubjectcells, bookyear1906
