The birth of genetics [by] Mendel, De Vries, Correns [and] Tschermak in English translation.

Date:
1950
Catalogue details

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

Credit: The birth of genetics [by] Mendel, De Vries, Correns [and] Tschermak in English translation. Source: Wellcome Collection.

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    8 GREGOR MENDEL once; thus the IVth case should occur four times as frequently as the 1st and twice as frequently as the Ilnd or Illrd. If on the other hand, plants grown from the round yellow seeds mentioned are fertilized by pollen from green angular plants, the results should be exactly the same, provided that the ovules are of the same types, and formed in the same proportions, as was reported for the pollen. I have not performed this experiment myself, but I believe, on the basis of similar experiments, that one can depend on the result indicated. In the same fashion individual experiments may be performed for each of the two seed characters separately, all those round seeds which occurred to¬ gether with angular ones, and all the yellow ones which occurred with green seeds on the same plant are suitable. If, for instance, a plant with green seeds was fertilized by one with yellow seeds, the seeds obtained should be either 1) aU yellow, or 2) half yellow and half green, since the plants originating from yellow seeds are of the varieties В and ВЪ. Since, furthermore, В and Bb occur in the ratio of 1:2, the 2nd fertilization will occur twice as frequently as the 1st. Regarding the other characters, the experiments may be conducted in the same way; results, however, will not be obtained until next year. I have all the piloselloid Hieracia which your honor recommends for the experiments; also H. murorum and H. vulgatum of the Archieracia; H. glaucum H. alpinum, H. amplexicaule, H. prenanthoides, and H. tridentatum do not occur in this vicinity. Last summer I found a withered Hieracium, which has the seed color of Prenanthoidea (Fries; Achaenia typice testaces [pallida]), but did not resemble any of the herbarium specimens of this type very closely; finally our botanist declared it to be a hybrid. The rootstock has been trans¬ planted to the garden for further observations, and the seeds have been planted. On the whole, this area is poor in Hieracia, and probably has not been sufficiently searched. Next summer I hope to have the time to roam the sandy lignite country which extends eastward from Brünn for several miles to the Hungarian frontier. Several other rare plants are known from this region. The Moravian plateau also is probably terra incognita as far as the Hieracia are concerned. If I should find anything noteworthy during the summer, I shall hurry to send it to your honor. At the moment permit me to include with the seed packets the plant just mentioned, albeit in a rather defective condi¬ tion, together with another Hieracium. Last year I found at least 50 specimens of it on an old garden wall. This plant is not found in the local herbaria; its appearance suggests both H. praealtum and H. echioides, without being one or the other. H. praealtum does occur in the environs of the city, H. echioides does not. Several specimens of the hybrid Geum urbanum-\-G. rivale (from last year's hybridization) wintered in the greenhouse. Three are now ñowering, the others will follow. Their pollen is fairly well developed, and the plants should be fertile, just as Gärtner states. It seems strange that all the plants now flower¬ ing are of the exceptional type mentioned by Gärtner. He says : ^'Geum urbano-rivale, mostly with large flowers, like rivale, and only a few specimens