. The cell in development and inheritance. Cells. D E F Fig. 122. — Origin of the tetrads by ring-formation in the spermatogenesis of the mole-cricket Gryllotalpa. [\"OM RaTH.] A. Primary spermatocyte, containing six double rods, each of which represents t%vo chromo- somes united end to end and longitudinally split except at the free ends. B. C. Opening out of the double rods to form rings. D. Concentration of the rings. E. The rings broken up into tetrads. F. First division-figure established. heterotypical mitosis (p. 86). The breaking of the ring into four parts involves, first, the se
. The cell in development and inheritance. Cells. D E F Fig. 122. — Origin of the tetrads by ring-formation in the spermatogenesis of the mole-cricket Gryllotalpa. [\"OM RaTH.] A. Primary spermatocyte, containing six double rods, each of which represents t%vo chromo- somes united end to end and longitudinally split except at the free ends. B. C. Opening out of the double rods to form rings. D. Concentration of the rings. E. The rings broken up into tetrads. F. First division-figure established. heterotypical mitosis (p. 86). The breaking of the ring into four parts involves, first, the separation of these two halves (corresponding with the original longitudinal split), and second, the transverse division of each half, the latter being the reducing division of Weismann. The number of primary rods, from which the rings arise, is one-half the somatic number. Hence each of them is conceived by Vom Rath, Hacker, and Riickert as bivalent or double; as representing two chromosomes united end to end. This appears with the greatest clearness in the spermatogenesis of Gryllotalpa (Fig. 122). Here. 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
