Replies to CD's questions on plant hybridisation and laws of inheritance. Rejects predominant transmission of characters by established forms. Males show predominance, but congeniality of parents' constitution to climate and soil more important. No correlation between hybridisation and variability, cultivation, and geographical distribution. Rejects reversion.
Describes experiments in Hippeastrum in which pollen from another species proved more fertile than plant's own pollen.
Did not intend to say that crossing is inimical to fertility.
I wish it was in my power to give definitive answers to Mr Darwin's questions. They are all fit points to be investigated, but they require a longer course of experience than the life of one man, especially of one who attends to the subject only incidentally, can furnish.
I can entertain no doubt whatsoever as to the first question, that a long established variety or species must be more likely to reproduce itself uniformly from seed than one of recent origin. You have experience of the reproduction in the first case, and no certainty at all in the 2
It stands to reason that the pollen of a plant which is naturally disposed to produce varieties must be less likely to produce hybrids of uniform appearance, than that of a plant which is not disposed to sport; but I consider the pollen of a permanent garden variety just as likely to produce an uniform effect as that of any easily convertible natural species. Take for instance the hollyhocks of the garden, without question cultivated varieties of one plant, yet steadily reproducing their respective colors by seed. I apprehend that the pollen of one variety of hollyhock on another would be neither more nor less decisive than that of one wild species of Calceolaria on another, at least taking the species wh. have similar constitutions & intermingle easily. These answers refer to Q
Qy 3. I think crossbred vegetables lean more to the type of the father than of the mother; but I think the offspring of the mule disposed to lean to the parent of w
4th. I am not aware that the genera which it is difficult to hybridize are slow to sport. Up to this day, tho' I am still trying, I have failed in all attempts to cross Crocuses, yet there is a different either species or var
8. I have never heard of any particular instance of the character w
The experience of 4 seasons has now shewn that it is certain that if, taking two hybrid Hippeastra wh. have (say) each a 4-flowered stem, 3 flowers on each are set with the dust of the plant itself & one on each with the dust of the other plant, that one on each of them will take the lead & ripen abundant seed, & the other 3 either fail or proceed more tardily & produce an inferior capsule of seed. I am at this moment trying the experiment in a bulb of that genus fresh from the Organ Mountains in Brazil to see whether its own natural pollen or that of a mule will take the lead.
I have answered the questions as well as I am able; but a much longer course of experiments in various genera is necessary to their perfect solution
I remain D
April 5 1839.
- f1 503.f1CD had sent his questions to Herbert via Henslow.
- f2 503.f2CD later used the information on Herbert's experiments on Hippeastrum in Natural selection, p. 399 and Variation 2: 138–9.
- f3 503.f3A. Walker 1838. In his dedication (pp. iii–iv) Alexander Walker defines his ‘law of nature’ as: ‘one parent gives to progeny the forehead and organs of sense, together with the nutritive organs contained within the trunk of the body; while the other parent gives the backhead and cerebel or organ of the will, together with the locomotive organs composing the exterior of the trunk and the whole of the limbs.’