From W. T. Thiselton-Dyer 11 May 1878
Royal Gardens Kew
May 11. 78
Dear Mr Darwin
Our indefatigable Lynch has taken your wants in hand and we will do the very best we can for you. It is good of you to let us supply you as of course it is honour and glory to us.1
I have not seen the paragraph in the Times but it must have sharply perverted what I said.2 It is always so with reporters; they have no genuine desire to understand one’s meaning and are too indifferent to make careful notes or ask for explanations afterwards if one’s meaning is not clear to them.
I certainly stated that the heliotropism of plants is something independent of the advantage gained by green plants moving towards the light though that movement is due to it. I deduce this statement—which I fear is not quite clear—from Vines’s work on the slowing effect of light on a hypha of Phycomyces which has no chlorophyll of course and therefore could gain nothing by heliotropism3 He attributes this “slowing” to a paralysis of the protoplasm produced by light preventing the extension of the contiguous cell wall. The protoplasm loses extensibility, the cell wall in intimate contact with it does the same. hence growth is locally arrested. Hence also on a large scale the multicellular plant curves over towards the light. This is undoubtedly in a green plant an advantage to it but I am so far heretical as to feel doubtful whether, from the facts, one can affirm that the advantage of heliotropism has brought it about. It appears to be a habit which plant-protoplasm contracted before it learned the chlorophyllian process. I offer this view with all possible submission— I think it is not the same thing quite as denying the advantage of heliotropism.
Your son Frank came down to see me and spent a most agreeable afternoon. He told me about the roots.4 I am immensely interested When you were at Kew I pointed out to you a very characteristic Example of positive heliotropism in the aerial roots of an orchid. The plant was one brought by Moseley from the Admiralty Islands.5 But I dare say with a little management we could get other less valuable specimens to show the same thing.
I am going away with my wife for a few days to the seaside6 and perhaps when you return to Down
CD annotations
Footnotes
Bibliography
Hemsley, William Botting. 1885–6. Report on the scientific results of the voyage of H.M.S. Challenger during the years 1873–76 (Botany). 2 vols. London: HMSO.
Vines, Sydney Howard. 1878. The influence of light upon the growth of unicellular organs. Arbeiten des botanischen Instituts in Würzburg 2 (1878–82): 133–47.
Summary
WTT-D’s statement perverted by Times [4 May 1878, p. 6, on WTT-D’s Royal Institution lectures on vegetable morphology].
S. H. Vines’s work on light inhibition of Phycomyces hyphae ["The influence of light upon the growth of unicellular organs" (1878), Arb. Bot. Inst. Würzburg 2 (1882): 133–47] suggests heliotropism in green plants is independent of, and more primitive than, photosynthesis.
Heliotropism in aerial roots.
Frank Darwin’s work.
Letter details
- Letter no.
- DCP-LETT-11503
- From
- William Turner Thiselton-Dyer
- To
- Charles Robert Darwin
- Sent from
- Kew
- Source of text
- DAR 209.8: 154
- Physical description
- inc ††
Please cite as
Darwin Correspondence Project, “Letter no. 11503,” accessed on 26 September 2022, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-11503.xml