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From C. G. Semper1   25 January 1874

Würzburg

25 Jan. 74.

Hochverehrter Herr

Es freut mich, Ihrem Wunsche, meine kurze Notiz über die Korallenriffe zu erhalten, nachkommen zu können. Ich schicke Ihnen den letzten Separatabzug meines Reiseberichts aus der Z. f. w. Zool. in welchem Sie pag. 563–569 meine Ansichten, sowie die Beobachtungen, auf welche ich sie gründe, auseinandergesetzt finden;2 der kurze Aufsatz ist ⁠⟨⁠wied⁠⟩⁠er 1869 in “Die Philippinen und ihre Bewohner” un⁠⟨⁠ver⁠⟩⁠ändert, nur um einen kurzen Nachtrag vermehrt und unter Hinweglassung des früheren Schlusssatzes, abgedruckt worden.3 Leider haben mannichfache Berufsgeschäfte mich verhindert, die versprochene weitere Ausführung meiner Ansichten zu liefern; doch gebe ich die Hoffnung noch nicht auf, mein Wort später einzulösen.4

Ausser den philippinischen Riffen, under denen einige Barrièrenriffe sind, habe ich die Pelew-Inseln und Riffe (u die westlichsten Carolinen) kennen gelernt.5 Auf den Pelew’s habe ich 10 Monate zugebracht; die grösste Mehrzahl ihrer Inseln und Riffe kenne ich aus eigener sehr genauer Untersuchung; ich habe dort vielfach selbst Sondirungen genommen und die Aussenseite wie Innenseite der westlichen und östlichen Riffe an windstillen Tagen genau beobachtet. Abgesehen von andere⁠⟨⁠n⁠⟩⁠ Gründen, welche Sie in dem kleinen Aufsatz angegeben finden, war es vor Allem der Nachweis bis zu reichlich 200' über dem Meer gehobener Korallenriffe, deren Petrefacten ganz modern sind, und der ganz allmälige Uebergang aller drei Riffarten—der Atolle, Barrienriffe und Küstenriffe—ineinander auf sehr kleinem Gebiete, welche mich zu Anschauungen zwangen, die von der Ihrigen abweichen;6 die durch viele (7) Jahre hindurch fortgesetzte Beobachtung der mechanischen Einmischung von Strömungen auf Intensität und Richtung des Wachsthums einzelner Korallenknollen wie ganzer Riffe hat mir, wie ich glaube, das Verständniss so äusserst complicirter Erscheinungen geliefert. Damit will ich die Möglichkeit nicht läugnen, dass auch Senkungen hin und wieder Atolle oder Barrierenriffe hervorgebracht haben können; aber sie allein reichen nicht aus. Ich habe hier wie auf so manchen andern Gebieten die Ueberzeugung gewonnen, dass in der Natur nah verwandte Resultate oft auf die verschiedenste Weise hervorgebracht werden können: ein Resultat, welches allerdings unter Umständen sehr hindernd werden kann, wenn es sich um die Formulirung von Gesetzen handelt.

Zu jeder weiteren Auskunft bin ich sehr gerne bereit.

Indem ich Sie schliesslich bitte, mich Ihrer nachsten Familie, sowie Sir John & Lady Lubbock7 bestens zu empfehlen, bin ich in grösster Hochachtung | Ihr ergebenster | C. Semper

1
For a translation of this letter , see Appendix I.
2
See letter to C. G. Semper, 21 January [1874]. CD’s annotated copy of Semper’s article (Semper 1863) is in DAR 177: 135, together with notes made by CD for changes to the new edition of Coral reefs. The article first appeared in Zeitschrift für wissenschaftliche Zoologie.
3
The section on coral reefs from Semper 1863, pp. 563–9 is reprinted in Semper 1869 (The Philippines and their inhabitants), pp. 100–8, except for the last paragraph of the original.
4
Semper did not return to his work on coral reefs.
5
The Pelew islands (now Palau) are the western part of the Caroline Islands, an archipelago in the western Pacific Ocean, just north of the equator (Columbia gazetteer of the world).
6
See letter to C. G. Semper, 21 January [1874] and n. 2. In Coral reefs 2d ed., pp. 223–4, CD discussed Semper’s objections to his view, but noted that when the land was prolonged beneath the sea in an extremely steep slope, reefs formed there during subsidence would remain closely attached to the shore, and would be indistinguishable from fringing reefs. CD concluded that he was justified in continuing to consider atolls and barrier reefs to be the result of subsidence.
7
John and Ellen Frances Lubbock were neighbours of CD.

From C. G. Semper1   25 January 1874

Würzburg

25 Jan. 74.

Most honoured Sir!

I am pleased to be able to comply with your request for a copy of my brief note on coral reefs. I am sending you the last offprint of my travel report in the Z. f. w. Zool., where on pp. 563–569 you will find an account of my views, as well as the observations on which they are based;2 this brief essay was reprinted in 1869 in “Die Philippinen und ihre Bewohner”, with no alterations other than a short postscript and the original conclusions left out.3 Unfortunately, manifold professional duties have prevented me from elaborating my views further, but I have not yet given up the hope of making good my promise later.4

Apart from the Philippine reefs, among which are a number of barrier reefs, I came to know the Pelew Islands and reefs (and the westermost Caroline Islands).5 On the Pelews I spent 10 months; the great majority of its islands and reefs I know from personal, very detailed examination; many times, I myself took soundings and carefully observed the outer and inner face of the westerly and easterly reefs on windless days. Apart from other reasons, which you will find listed in my little essay, it was above all the evidence of coral reefs that are raised at least 200’ above sea level, and whose petrifaction is very recent, and also the very gradual transition of all three kinds of reef—atolls, barrier and coastal reefs—into one another within a very small area, which compelled me to embrace views which diverge from yours.6 The observations made over a period of many (7) years of the mechanical interference of currents on the rate and direction of the growth both of single coral nodules and of entire reefs have afforded me, I believe, an understanding of these extremely complex phenomena. I do not mean thereby to deny the possibility that atolls or barrier reefs have occasionally been the product of subsidence; but this by itself is insufficient. Here as elsewhere I have come to the conclusion that in nature, very similar effects can frequently be the result of very different processes: a result which, in certain cases, however, can be a hindrance when it comes to formulating laws.

I am more than willing to answer any further questions.

In closing, may I ask you to remember me to your immediate family, as well as to Sir John & Lady Lubbock.7 Yours | most respectfully | and most devotedly | C. Semper

1
For a transcription of this letter in its original German, see Transcript.
2
See letter to C. G. Semper, 21 January [1874]. CD’s annotated copy of Semper’s article (Semper 1863) is in DAR 177: 135, together with notes made by CD for changes to the new edition of Coral reefs. The article first appeared in Zeitschrift für wissenschaftliche Zoologie.
3
The section on coral reefs from Semper 1863, pp. 563–9 is reprinted in Semper 1869 (The Philippines and their inhabitants), pp. 100–8, except for the last paragraph of the original.
4
Semper did not return to his work on coral reefs.
5
The Pelew islands (now Palau) are the western part of the Caroline Islands, an archipelago in the western Pacific Ocean, just north of the equator (Columbia gazetteer of the world).
6
See letter to C. G. Semper, 21 January [1874] and n. 2. In Coral reefs 2d ed., pp. 223–4, CD discussed Semper’s objections to his view, but noted that when the land was prolonged beneath the sea in an extremely steep slope, reefs formed there during subsidence would remain closely attached to the shore, and would be indistinguishable from fringing reefs. CD concluded that he was justified in continuing to consider atolls and barrier reefs to be the result of subsidence.
7
John and Ellen Frances Lubbock were neighbours of CD.

Please cite as “DCP-LETT-9255,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-9255