Experiments in plant hybridisation / Mendel's original paper in English translation, with commentary and assessment by Sir Ronald A. Fisher, together with a reprint of W. Bateson's biographical notice of Mendel ; edited by J.H. Bennett.

  • Mendel, Gregor, 1822-1884. Versuche über Pflanzenhybriden. English
Date:
[1965]
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Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Experiments in plant hybridisation / Mendel's original paper in English translation, with commentary and assessment by Sir Ronald A. Fisher, together with a reprint of W. Bateson's biographical notice of Mendel ; edited by J.H. Bennett. Source: Wellcome Collection.

    56/116 (page 42)
    42 EXPERIMENTS IN PLANT HYBRIDISATION known, is not the case since it is precisely under such circum¬ stances that not only the most varied but also the most variable forms are found. It is only the Leguminosae^ like Pisum, Phaseo- lus,^ Lens, whose organs of fertilisation are protected by the keel, which constitute a noteworthy exception. Even here there have arisen numerous varieties during a cultural period of more than looo years under most various conditions; these maintain, however, under unchanging environments a stability as great as that of species growing wild. It is more than probable that as regards the variability of cultivated plants there exists a factor which so far has received little attention. Various experiments force us to the conclusion that our cultivated plants, with few exceptions, are members of various hybrid series, whose further development in conform¬ ity with law is varied and interrupted by frequent crossings inter se. The circumstance must not be overlooked that culti¬ vated plants are mostly grown in great numbers and close together, affording the most favourable conditions for reciprocal fertilisation between the varieties present and the species itself. The probability of this is supported by the fact that among the great array of variable forms solitary examples are always found, which in one character or another remain constant, if only foreign influence be carefully excluded. These forms behave precisely as do those which are known to be members of the compound hybrid series. Also with the most susceptible of all characters, that of colour, it cannot escape the careful observer that in the separate forms the inclination to vary is displayed in very different degrees. Among plants which arise from one spontaneous fertilisation there are often some whose offspring vary widely in the constitution and arrangement of the colours, while that of others shows little deviation, and among a greater number solitary examples occur which transmit the colour of the flowers unchanged to their offspring. The cultivated species of Dianthus afford an instructive example of this. A white-flowered example of Dianthus caryophyllus, which itself was derived from a white- flowered variety, was shut up during its blooming period in a * [Phaseolus nevertheless is insect-fertilised.]