[64] Knowing my interest in this subject Professor Weldon was so good as to forward to me a series of his peas arranged to form a scale of colours and shapes, as represented in his Plate I. I have no doubt that the use of such colour-scales will much facilitate future study of these problems.
[65] I notice that Vilmorin in the well-known Plantes Potagères, 1883, classifies the intermediate-coloured peas with the green.
[66] Similarly though tall and dwarf are Mendelian characters, peas occur of all heights and are usually classified as tall, half-dwarfs, and dwarfs.
[67] Wrinkling must of course be distinguished further from the squaring due to the peas pressing against each other in the pod.
In connexion with these considerations I may mention that Vilmorin makes the interesting statement that most peas retain their vitality three years, dying as a rule rapidly after that time is passed, though occasionally seeds seven or eight years old are alive; but that wrinkled peas germinate as a rule less well than round, and do not retain their vitality so long as the round. Vilmorin-Andrieux, Plantes Potagères, 1883, p. 423. Similar statements regarding the behaviour of wrinkled peas in India are made by Firminger, Gardening for India, 3rd ed. 1874, p. 146.
[68] Cotyledon-colour is not nearly so sensitive to ordinary changes in conditions as coat-colour, provided the coat be uninjured. But even in monomorphic green varieties, a seed which for any cause has burst on ripening, has the exposed parts of its cotyledons yellow. The same may be the case in seeds of green varieties injured by Bruchus or birds. These facts make one hesitate before denying the effects of conditions on the cotyledon-colour even of uninjured seeds, and the variation described above may have been simply weathering. The seeds were gathered very late and many were burst in Laxton’s Alpha. I do not yet know they are alive.
[69] It is interesting to see that in at least one case the same—or practically the same—variety has been independently produced by different raisers, as we now perceive, by the fortuitous combination of similar allelomorphs. Sutton’s Ringleader and Carter’s First Crop (and two others) are cases in point, and it is peculiarly instructive to see that in the discussion of these varieties when they were new, one of the points indicating their identity was taken to be the fact that they produced the same “rogues.” See Gard. Chron. 1865, pp. 482 and 603; 1866, p. 221; 1867, pp. 546 and 712.
Rimpau quotes Blomeyer (Kultur der Landw. Nutzpflanzen, Leipzig, 1889, pp. 357 and 380) to the effect that purple-flowered plants with wrinkled seeds may spring as direct sports from peas with white flowers and round seeds. I have not seen a copy of Blomeyer’s work. Probably this “wrinkling” was “indentation.”
[70] The asymmetries here conceived may of course be combined in an inclusive symmetry. Till the differentiation can be optically recognized in the gametes we shall probably get no further with this part of the problem.
[71] Materials for the Study of Variation, 1894, p. 78.