The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . truecases of vegetative mutations. Even then we shouldrequire the proof that the deviating branches will re-produce their type from their seeds, after pure self-fer-tilization. In manv cases, however, this is not possiblebecause the bud-variations in question often bear noseeds, even when they occur regularly, as in Cephalo-fariis pediinculata fastir/iafa (p. 109. Fig. 16) and innumerous other conifers, the bud-variations of whichhave been described by Betssner: as, for instance, inCryptonicri
The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . truecases of vegetative mutations. Even then we shouldrequire the proof that the deviating branches will re-produce their type from their seeds, after pure self-fer-tilization. In manv cases, however, this is not possiblebecause the bud-variations in question often bear noseeds, even when they occur regularly, as in Cephalo-fariis pediinculata fastir/iafa (p. 109. Fig. 16) and innumerous other conifers, the bud-variations of whichhave been described by Betssner: as, for instance, inCryptonicria japonica spiraliter falcata (Fig. 138, p. 619).Even from the i^Teen Dahlia I was, unfortunatelv, unable ^ See above p. in and pp. 272-277. Vegetative Mutatiuns. C)29 to obtain any seed (Fig. 137, p. 61S), l)ccaiise it ilnu-ered too late in the year. I have cultivated this plant,which was descril^ed and figured in the first section ofthis volume (p. 92), for many years by vegetative meth-ods, because it is perfectly sterile. In the summer of1902, however, it suddenly began to produce bud-varia-. Fig. 143. Carpinus Betulus. At a. a partly variegated leafon a tree which had otherwise only green leaves, Ililvcr-sum (1887). tions. distributed in considerable numbers over the variousmain stems; they were apparently independent n{ oneanother, but seemed to arise in response to the same un-known external influences. The fiowerheads of the ata-vistic branches were of the normal structure of the ordi-nary Dahlias, double, and with carmine red florets, at thetip of each of whicli was a white spot. From this we 630 / \ilidity of the Doctrine of Mutation. may conclude that this f^reen Dahha had arisen from tliecorresponding double-liowered variety. I do not propose to adduce any further instances;those which I liave given show that varietal charactersma} chsai)pear in a vegetative way, the original char-acters becoming actixe again. For such a mutationneither the formation of sexual cells
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