Problems of genetics / by William Bateson.

  • Bateson, William, 1861-1926.
Date:
1913
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Problems of genetics / by William Bateson. Source: Wellcome Collection.

    132/290 (page 110)
    no PROBLEMS OF GENETICS owing to defective constitution {e. g., the albinos of Antirrhinum studied by Baur, and the homozygous yellow mice). I am rather inclined to suppose that in these examples of hybrids breeding true we shall find a state of things comparable with that to which we formerly applied the terms coupling and repulsion. In these cases certain of the possible combinations of factors occur in the gametic series with special frequency, being in excess, while the gametes representing other combina¬ tions are comparatively few. In a recent paper on these cases Professor Punnett and I have shown that these curious results vary according to the manner in which the factors are grouped in the parents. If A and В are two factors which exhibit these phenomena we find that the gametic series of the double heterozy¬ gote differs according as the combination is made by crossing ABXab, or by crossing AbXaB. In a normal Mendelian case the Fl form, AaBb, produces gametes AB, Ab, аВ, ab, in equal numbers; but in these peculiar cases those gametes which contain Gametic series Number Number of —. of gametes zygotes ai in series formed A£ Ab аВ ab in Partial repulsion from zygote of form AbXaB I (и—l) (и—l) I 2П I 31 31 I 64 I IS 15 I 32 17 7 I 16 4«^ 4096 1024 256 I 3 31 8 II 114 64 16 Partial coupling from zygote of form ABXab 31 13 8 71 I 7 16 64 256 1024 4096 16384 4П2 , IS I I IS 32 31 I I 31 64 63 I I 63 128 ^(и —i) I I (и —l) 2П Nature of zygotic series AB Ab аВ ab Partial repulsion from zygote ^ of form AbXaB 2И2+1 «2—1 —I 2049 1023 1023 513 255 255 129 63 63 33 15 IS 9 3 3 Partial coupling from zygote of form AB Xab 41 7 7 9 177 15 IS 49 737 31 31 225 3009 63 63 961 12161 127 127 3969 .3w2 —(2И—l) 2M—I 2И —I «2—(2M —l)