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Letter 5004A

Müller, J. F. T. to Darwin, C. R.

13 Feb 1866

    Summary Add

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    Thanks CD for Journal of researches.

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    Insect genus Elater is an exception to the rule that all luminous organs give out a green light.

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    Gives some observations on climbing plants at Itajahy.

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    His study of orchids has convinced him of the value of CD's book.

Transcription

Desterro,

13. Februar 1866.

Verehrter Herr!

Ich empfing Ihre freundlichen Briefe vom 17. October und vom 9. Dezember und auch Ihr ``Journal of Researches'', wofür ich Ihnen noch meinen aufrichtigen Dank sagen darf. Ich lese das Buch jetzt mit ausserordentlichem Interesse.

Sie bemerken (S. 30), dass bei all den verschiedenen Arten von leuchtenden Thieren, welche Sie beobachtet haben, das Licht von deutlich grüner Farbe gewesen ist. Ich habe dieselbe Beobachtung gemacht bei Seethieren (Renilla, Noctiluca, Beroë u. s. w.), aber bei den Insecten giebt es einige Ausnahmen. Die verschiedenen Arten von leuchtenden Elateren, welche ich gesehen habe, besitzen ausser den beiden Lichtern am Thorax noch einen leuchtenden Fleck an der Bauchseite des ersten Hinterleibsegments; wenn das Insect in Ruhe ist oder umherkriecht, so ist dieser Fleck nicht sichtbar; er wird aber sichtbar, sobald der Hinterleib in die Höhe gebogen wird oder wenn der Elater fliegt. Das Licht dieses Flecks ist sogar heller als das der beiden anderen und von gelber Farbe, sehr verschieden von dem grünlichen Licht der Thorax-Flecken.

&lldots; . Eine kleine Art von Elater hat zwei leuchtende Punkte mehr, welche wie diejenige der Glühwürmer an dem hinteren Theil des Abdomen gelegen sind. Ungefähr vor 12 Jahren fand ich in dem Urwalde am Itajahy-Fluss eine sehr merkwürdige leuchtende Käferlarve, welche leuchtende Flecke an allen ihren Leibesringeln hatte; einige von diesen Flecken (wenn ich mich recht entsinne, diejenigen des Vorderendes) waren von leuchtendem Roth, einige waren gelb, und der grösste Theil grün. Die Larve konnte alle oder auch einige von ihren leuchtenden Flecken verdunkeln; wenn sie gereizt wurde, so strahlten alle ein prächtiges Licht aus. Die Larve scheint sehr selten zu sein; mein Bruder, der am Itajahy seit 1852 lebt, hat sie nur ein einziges Mal gefunden.

Es ist mir sehr schmeichelhaft, dass Sie meine Bemerkungen über Kletterpflanzen für werth gehalten haben, der Linnaean Soc. vorgelegt zu werden.

&lldots; . Im letzten Monat habe ich drei Wochen zu einer Reise nach dem Itajahy-Fluss verwendet, wo ich mich wiederum an der Pracht unserer Urwälder erfreute. Ich sah mich nach Kletterpflanzen um; aber ich habe nur einen einzigen Fall von einer Pflanze bemerkt, welche einen dicken Stamm erkletterte (ungefähr 5 Fuss im Umfang); nach dem Bau des Holzes und dem bitteren Geschmack glaube ich, dass es eine Menispermee war; sie hatte ungefähr 3 Zoll Durchmesser und kletterte in einer lockeren Spirale von links nach rechts. Die meisten Kletterpflanzen, welche dicke Bäume erstiegen, waren Wurzelklimmer (Farne, Aroideen, Begonia u. s. w.); ich fand auch einige Rankenklimmer (Haplolophium, Bignonia, Cissus u. s. w.).— Am oberen Itajahy sah ich zahlreiche schwarze Schnüre (von einigen Linien bis zu beinah ein Zoll Durchmesser[)], spiralig um die Stämme einiger mächtigen Bäume gewunden, und ich glaubte zuerst, es wären Kletterpflanzen, welche die Bäume erstiegen; später aber fand ich, dass es Luftwurzeln waren von einem Philodendron, welches auf den Zweigen jener Bäume lebte und von dort die Wurzeln nach der Erde sandte. Es giebt einige andere Arten von Philodendron, deren Luftwurzeln immer frei von den Zweigen herunterhängen und senkrecht zur Erde wachsen, wobei sie oftmals eine Länge von mehr als 50 m erreichen.

&lldots; . Was Orchideen anbetrifft, so habe ich die gute Gelegenheit, Arten aus all den verschiedenen Gruppen zu beobachten und so viele von den wundervollen Anpassungen zu sehen, welche in Ihrem Orchideen-Buch beschrieben sind, und mich so von der Richtigkeit Ihrer Beobachtungen zu überzeugen&lldots; .

Translation

Desterro,

13 February 1866.

Dear Sir!

I have received your kind letters of 17 October and 9 December and also your ``Journal of Researches'', for which I convey my sincere thanks. I am currently reading the book with the greatest interest.

You note (p. 30) that the light was clearly green in all the different species of luminous animals that you have observed. I have made the same observation in maritime animals (Renilla, Noctiluca, Beroe etc.), but there are some exceptions among insects. The various species of luminous Elaters that I have seen possess not only the two lights on the thorax but also a luminous spot on the belly of the first abdominal segment. When the insect is still or crawls around, this spot remains invisible, but it becomes visible as soon as the abdomen is bent into the air or the Elater flies. The light from this spot is even brighter than that from the two others and it is yellow in colour, quite different from the greenish light of the thoracic spots.

&lldots; . One small Elater species has two more luminous spots on the hind part of the abdomen, just like those of glow-worms. About 12 years ago I found a very strange luminous beetle larva in the jungle by the Itajahy river. It had luminous spots on all its abdominal annuli, of which some (if I remember correctly, those at the front end) were bright red, some were yellow, and most were green. The larva was capable of dimming some or all of its luminous spots; when it was irritated they all radiated a splendid light. The larva seems to be very rare; my brother, who has lived by the Itajahy since 1852, has encountered it only once.

I am highly flattered that you found my comments on climbers worthy of being presented at the Linnean Society.

&lldots; . Last month I spent three weeks travelling to the Itajahy river, where I enjoyed the splendour of the jungles anew. I looked for climbers, but I noticed only one single example of a plant that climbed a broad tree trunk (roughly 5 feet in circumference). Judging by the structure of the wood and the bitter flavour I think it was a Menispermum; it was about 3 inches in diameter and climbed in a loose spiral from left to right. Most of the climbers scaling broad-girthed trees were root-climbers (ferns, Aroides, Begonia etc.), but I also found a few hook-climbers (Haplolophium, Bignonia, Cissus etc.).— At the upper Itajahy I saw numerous black strings (ranging from a few lines to an inch in diameter), wound in spirals around a number of huge trees; at first I thought they were climbers scaling the trees, but later I discovered that they were aerial roots of a Philodendron that lived on the branches of those trees, from where it sent roots towards the earth. There are some other species of Philodendron whose aerial roots always hang down freely from the branches, growing vertically towards the ground, often reaching a length exceeding 50 m.

&lldots; . Concerning orchids, I have good opportunities to observe species from all the various groups and to see so many of the wonderful adaptations that are described in your orchid book, and thus to convince myself of the correctness of your observations&lldots;

    Footnotes Add

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    f1 5004a.f1
    For a translation of this letter, see Appendix I. According to Alfred Möller, all Fritz Müller's letters to CD were written in English (see Möller ed. 1915--21, 2: 72 n.); most of them have not been found. Many of the letters were later sent by Francis Darwin to Möller, who translated them into German for his Fritz Müller: Werke, Briefe und Leben (Möller ed. 1915--21). Möller also found final drafts of some Müller letters among the Fritz Müller papers and included these in their original English form (ibid., 2: 72 n.). Where the original English versions are missing, the published version, usually appearing in German translation, has been used.
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    f2 5004a.f2
    See Correspondence vol. 13, letters to Fritz Müller, 17 October [1865] and 9 December [1865]; for CD's offer to send a copy of the Journal of researches, see Correspondence vol. 13, letter to Fritz Müller, 20 September [1865] and n. 14. CD probably sent the second edition, which had been reprinted in 1860 (Freeman 1977, p. 40).
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    f3 5004a.f3
    In Journal of researches 2d ed., pp. 29--30, CD had written: It is remarkable that in all the different kinds of glowworms, shining elaters, and various marine animals (such as the crustacea, medusæ, nereidæ, a coralline of the genus Clytia, and Pyrosoma), which I have observed, the light has been of a well-marked green colour.
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    f4 5004a.f4
    The river to which Müller refers is the Itajaí Açu in Santa Catarina province, Brazil.
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    f5 5004a.f5
    As evidence against the role of luminosity in the behaviour of mating insects, CD cited Müller's observation that a beetle larva was the most luminous insect that he had seen in Brazil (Descent 1: 345).
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    f6 5004a.f6
    Fritz Müller and his brother August emigrated together from Germany to Brazil in 1852. For an account of their settlement on the Itajaí Açu river, and Fritz Müller's return visits from Destêrro, where he taught mathematics from 1856, see Möller ed. 1915--21, 3: 45 et seq.; see also West 2003, pp. 65--96.
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    f7 5004a.f7
    CD had edited comments relating to `Climbing plants', made by Müller in three letters to CD, and communicated them to the Linnean Society (see Correspondence vol. 13, letter from Fritz Müller, [12 and 31 August, and 10 October 1865] and n. 1); the paper was read on 7 December 1865, and published as F. Müller 1865b.
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    f8 5004a.f8
    CD added to F. Müller 1865b a short account of the climbing of a trunk roughly five feet in circumference by a probable member of the Menispermaceae (see also Correspondence vol. 13, letter from Fritz Müller, [12 and 31 August, and 10 October 1865] and n. 19). The structures of the wood of the climbing plants listed in this letter are described and illustrated in F. Müller 1866b, of which there is an annotated copy in the Darwin Pamphlet Collection--CUL.
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    f9 5004a.f9
    CD added Müller's description of the aerial roots to Climbing plants 2d ed., p. 188 n., and added: These roots therefore seem to be true twiners, though they use their powers to descend, instead of to ascend like twining plants. The aërial roots of some other species of Philodendron hang vertically downwards, sometimes for a length of more than fifty feet.
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    f10 5004a.f10
    Müller refers to Orchids; CD added new information provided by Müller to the second edition. See, for example, letters from Fritz Müller, 2 August 1866, n. 5, and 1 December 1866, n.4.
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