He proceeds to a discussion of the Telephone and Telegraph group and recites facts, which I do not doubt for a moment, showing that in this group of peas—which have unquestionably been more or less “blend” or “mosaic” forms from their beginning—the “laws of dominance and segregation” do not hold. Professor Weldon’s collection of the facts relating to Telephone, &c. has distinct value, and it is the chief addition he makes to our knowledge of these phenomena. The merit however of this addition is diminished by the erroneous conclusion drawn from it, as will be shown hereafter. Meanwhile the reader who has studied what has been written above on the general questions of stability, “purity,” and “universal” dominance, will easily be able to estimate the significance of these phenomena and their applicability to Mendel’s hypotheses.
D. Miscellaneous cases in other plants and animals.
Professor Weldon proceeds:
“In order to emphasize the need that the ancestry of the parents, used in crossing, should be considered in discussing the results of a cross, it may be well to give one or two more examples of fundamental inconsistency between different competent observers.”
The “one or two” run to three, viz. Stocks (hoariness and colour); Datura (character of fruits and colour of flowers); and lastly colours of Rats and Mice. Each of these subjects, as it happens, has been referred to in the forthcoming paper by Miss Saunders and myself. Datura and Matthiola have been subjected to several years’ experiment and I venture to refer the reader who desires to see whether the facts are or are not in accord with Mendel’s expectation and how far there is “fundamental inconsistency” amongst them to a perusal of our work.
But as Professor Weldon refers to some points that have not been explicitly dealt with there, it will be safer to make each clear as we proceed.
1. Stocks (Matthiola). Professor Weldon quotes Correns’ observation that glabrous Stocks crossed with hoary gave offspring all hoary, while Trevor Clarke thus obtained some hoary and some glabrous. As there are some twenty different sorts of Stocks[128] it is not surprising that different observers should have chanced on different materials and obtained different results. Miss Saunders has investigated laws of heredity in Stocks on a large scale and an account of her results is included in our forthcoming Report. Here it must suffice to say that the cross hoary ♀ × glabrous ♂ always gave offspring all hoary except once: that the cross glabrous ♀ × hoary ♂ of several types gave all hoary; but the same cross using other hoary types did frequently give a mixture, some of the offspring being hoary, others glabrous. Professor Weldon might immediately decide that here was the hoped for phenomenon of “reversed” dominance, due to ancestry, but here again that hypothesis is excluded. For the glabrous (recessive) cross-breds were pure, and produced on self-fertilisation glabrous plants only, being in fact, almost beyond question, “false hybrids” (see p. [34]), a specific phenomenon which has nothing to do with the question of dominance.
Professor Weldon next suggests that there is discrepancy between the observations as to flower-colour. He tells us that Correns found violet Stocks crossed with “yellowish white” gave violet or shades of violet flaked together. According to Professor Weldon
“On the other hand Nobbe crossed a number of varieties of M. annua in which the flowers were white, violet, carmine-coloured, crimson or dark blue. These were crossed in various ways, and before a cross was made the colour of each parent was matched by a mixture of dry powdered colours which was preserved. In every case the hybrid flower was of an intermediate colour, which could be matched by mixing the powders which recorded the parental colours. The proportions in which the powders were mixed are not given in each [any] case, but it is clear that the colours blended[129].”
On comparing Professor Weldon’s version with the originals we find the missing explanations. Having served some apprenticeship to the breeding of Stocks, we, here, are perhaps in a better position to take the points, but it is to me perfectly inexplicable how in such a simple matter as this he can have gone wrong.