. The physical basis of heredity . Fig. 17.—Spermatogenesis of Ancyracanthus. Spermatogonia! cell, o; cell after growthperiod with tetrads, 6; first spermatocyte division, c; two cells resulting from first divisionwith six and with five chromosomes, respectively, d; four cells resulting from the nextdivision, e; ditto, /; mature spermatozoa, one with six, the other with five, chromosomes, g;ditto, living spermatozoa, h. (After Mulsow.) some, while the female has two sex-chromosomes. Bothsexes have ten other chromosomes, sometimes called auto-somes. Just before the maturation divisions take pla
. The physical basis of heredity . Fig. 17.—Spermatogenesis of Ancyracanthus. Spermatogonia! cell, o; cell after growthperiod with tetrads, 6; first spermatocyte division, c; two cells resulting from first divisionwith six and with five chromosomes, respectively, d; four cells resulting from the nextdivision, e; ditto, /; mature spermatozoa, one with six, the other with five, chromosomes, g;ditto, living spermatozoa, h. (After Mulsow.) some, while the female has two sex-chromosomes. Bothsexes have ten other chromosomes, sometimes called auto-somes. Just before the maturation divisions take place,there are six rods in each sperm-cell, five of which (theautosomes) condense into tetrads, the sixth (the sex-chromosome) into only a double body (Fig. 17, h). Aspindle develops about these and each of the five auto-somes divides. The sex-chromosome does not divide, butpasses to one pole of the spindle (Fig. 17, c). The result MECHANISM IN SEOEEOATION 43 is that two cells are produced, one with six, the otherwith five chromos
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