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.

    54/116 (page 40)
    40 EXPERIMENTS IN PLANT HYBRIDISATION Even these enigmatical results, however, might probably be explained by the law governing Pisum if we might assume that the colour of the flowers and seeds of Ph. multiflorus is a combination of two or more entirely independent colours, which individually act like any other constant character in the plant. If the flower-colour A were a combination of the indivi¬ dual characters which produce the total impression of a purple coloration, then by fertilisation with the diflFeren- tiating character, white colour, a, there would be produced the hybrid unions and so would it be with the cor¬ responding colouring of the seed-coats.* According to the above assumption, each of these hybrid colour unions would be independent, and would consequently develop quite independently from the others. It is then easily seen that from the combination of the separate developmental series a com¬ plete colour-series must result. If, for instance, A = A^-\-A,^, then the hybrids A^a and A^a form the developmental series— A2 -[2^2^ ~f-ö. The members of this series can enter into nine different combinations, and each of these denotes another colour— 1 Aj^A2 2 I A2a 2 ^1^2« 4 А^Аф 2 A^aa I A^ 2 A^aa i aa. The figures prescribed for the separate combinations also indicate how many plants with the corresponding colouring belong to the series. Since the total is sixteen, the whole of the colours are on the average distributed over each sixteen plants, but, as the series itself indicates, in unequal proportions. Should the colour development really happen in this way, we could offer an explanation of the case above described, viz. that the white flowers and seed-coat colour only appeared * [As it fails to take account of factors introduced by the albino this representation is imperfect. It is however interesting to know that Mendel realised the fact of the existence of compound characters, and that the rarity of the white récessives was a consequence of this resolution,]