The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . theinevitable interference of insects in pollination it seemedto me impossible to do this for both supposed races atthe same time, so I determined to isolate the 13-rayedform first, and the 21-rayed later on from a new mixedcrop. I devoted the two years 1893 and 1894 to theformer inquiry. With this object in view, I eradicated every indi-vidual of the mixed crop of 1892 wiiich had more than13 rays, as soon as I had counted the rays on its terminalflowerhead. In this way only 15 plants were sav
The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . theinevitable interference of insects in pollination it seemedto me impossible to do this for both supposed races atthe same time, so I determined to isolate the 13-rayedform first, and the 21-rayed later on from a new mixedcrop. I devoted the two years 1893 and 1894 to theformer inquiry. With this object in view, I eradicated every indi-vidual of the mixed crop of 1892 wiiich had more than13 rays, as soon as I had counted the rays on its terminalflowerhead. In this way only 15 plants were saved, ofwhich one had 12 and the rest 13 ligulate florets; the rest The Origin of Chrysanthemum Segetum Plenum. 169 were removed so early that there was no danger of these15 being fertihzed by them. These plants flowered abun-dantly from their lateral shoots but exhibited no tendencyto form a curve with an apex at 21. They were there-fore sufficiently pure representatives of the supposedrace. In September I harvested the seeds of the 13-rayedplants which I had spared, and sowed half of them in the. 12 13 A 17 18 19 20 21 22 23 24 25 26 27 28 B Fig. 31. A. Chrysanthemum segetum. B. Chrysanthemumsegetum grandiRorum (after purification). Curves ofthe races after isolation. A, Curve of the 13-rayed racein 1894. B, Curve of the 21-rayed race in 1897. Theordinates give the number of individuals with likenumber of ray-florets in the primary inflorescences ofthe individual plants. The numbers of ray-florets them-selves are given below the abscissa. following spring (1893). I raised 162 flowering indi-viduals, and recorded the numbers of rays on their ter-minal heads. The curve representing this generationwas steep, monomorphic and symmetrical (see Fig. 31Afor 1894), and agrees satisfactorily with the curves,given above, for the plants from the wild locality (p. 167and Fig. 32, Vol. I, p. 152). Therefore there can be no 170 Observation of the Origin of Juirieties. doubt tliat the wild for
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