The cotton plant in Egypt, studies in physiology and genetics . ants whichmost resemble the Upland parent in this respect did notexceed-0-130, and formed two modes, one on and behind0-085, the other on 0105. Again, though classificationaccording to habit of branching showed no marked shift-ing of the group-centre, yet the unbranched plantsfilled up the 0120 mode, while freely branchedoccupied the mode at 0-140 (Fig. 69). Two general conclusions result from this , that the modes in the F2 curve are genuine, andlargely due to autogenous fluctuation. Secondly, that the Fo curve co
The cotton plant in Egypt, studies in physiology and genetics . ants whichmost resemble the Upland parent in this respect did notexceed-0-130, and formed two modes, one on and behind0-085, the other on 0105. Again, though classificationaccording to habit of branching showed no marked shift-ing of the group-centre, yet the unbranched plantsfilled up the 0120 mode, while freely branchedoccupied the mode at 0-140 (Fig. 69). Two general conclusions result from this , that the modes in the F2 curve are genuine, andlargely due to autogenous fluctuation. Secondly, that the Fo curve consists of superposedcurves having the 3 : 1 form, but mutually obscurant untilgroups of comparable individuals are taken. Thus we have shown that light seed is segregating fromheavy seed in F2, probably as a simple pair of allelo-morphs, just as in the Afifi x Truitt series. The onlyserious weakness of this view lies in the fact that boththe parents were light-seeded ! The Upland parent, how-ever, bore these light seeds inside a boll of 32 mm. IX HEREDITY 171. 0-050 0-100 0150 grains. Fk;. B9. -Dissection of Mkan Skkd-Weioht in F.,. The F.^ curve of Fig. 68, dissected in respect of four correlatedcharacters. 172 THE COTTON PLANT IN EGYPT chap. diameter, while the Egyptian boll was only 27 mm. indiameter. On crossing the two strains we effectivelyplaced the Egyptian seed inside a boll whose cubiccapacity had been doubled, and an increase in seed-sizefollowed. Thus we may regard the Egyptian seed asbeing constitutionally large, and dominant over thegenuinely small Upland seed. At gametogenesis in Fj,the two seed-weight allelomorphs separate from oneanother, and the 3 : 1 ratio appears in F2 if we clearaway the lumber brought in by autogenous fluctuation. We have discussed this masking of the difference inseed-weight, and the development of the difference underequal opportunities, in terms of boll-width alone forconvenience, though other factors are also involved. Thedisplacement
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