. The physical basis of heredity . l of which, except ZZ separate at the first maturationdivision, 8 going to one pole and 8 to the other. One Ba-predd Blacky ^ z^z^ zV z^z^ zV 1 Barred J* Barred ( z^z^ z^z*^ zV zV Barredc? Barred c? Barred o BlacRo Fig. 77.—Scheme showing the transmission of the sex-Hnked characters B =barred, andb =black in the cross shown in Fig. 76. daughter cell gets both Zs {8-\- 2). This cell then dividesagain, the Zs presumably separating so that two secondspermatocytes are produced, each with 9 chromosomes(8+1), including the Z. These become the functionalsperm. The o

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. The physical basis of heredity . l of which, except ZZ separate at the first maturationdivision, 8 going to one pole and 8 to the other. One Ba-predd Blacky ^ z^z^ zV z^z^ zV 1 Barred J* Barred ( z^z^ z^z*^ zV zV Barredc? Barred c? Barred o BlacRo Fig. 77.—Scheme showing the transmission of the sex-Hnked characters B =barred, andb =black in the cross shown in Fig. 76. daughter cell gets both Zs {8-\- 2). This cell then dividesagain, the Zs presumably separating so that two secondspermatocytes are produced, each with 9 chromosomes(8+1), including the Z. These become the functionalsperm. The other spermatocyte, the one without a Z,may divide again, but it, or its products, degenerate, andnever produce sperm. According to Guyer, there are 17chromosomes in the female, including one Z. Presum-ably, then, after reduction half of the eggs; will contain aZ (8 + 1), the other half will be without it (8). The eggthat carries a Z (8 + 1), fertilized by a sperm (each spermcarries sl Z (8 + 1)), will make a male with 18 chromo-. Sl^-;

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Keywords: ., bookcentury1900, bookdecade1910, booksubjectheredit, bookyear1919