From Victor Hensen1   25 May 1881

Kiel

d. 25ten Mai 1881.

Sehr verehrter Herr!

So eben erhalte ich Ihr sehr freundliches Schreiben. Ich würde es nicht genug bedauern konnen, wenn Ihr werthvolles Werk über Kreuz und Selbst-Befruchtung der Pflanzen mir entgangen wäre, zum Glück war dasselbe in meinem Besitz und Sie werden vielleicht mit der Zeit selbst Ihre Pflanze “Heros” gehörigen Ortes berücksichtigt finden.2 Ueberhaupt sind Ihre Werke für mich eine Fundgrube gewesen, wie ich glaube, sind die Fälle selten, in welchen ich eine erheblich andere Meinung vertrete, wie die von Ihnen ausgesprochene.

Ihrem Werk über den Regenwurm sehe ich mit grosser Spannung entgegen, dies ist es auch, was mich zu der unmittelbaren Beantwortung Ihres freundlichen Briefes veranlasst.3

Der dänische Zoologe P. E. Müller hat in Tidsskrift for Skovbrug Bd III I u II Hft. Kjobenhavn 1878 in den “Studier over Skovjord” (Walderde) die Thätigkeit des Regenwurms weiter untersucht; ich selbst habe mir diese Arbeit noch nicht verschaffen können, da Sie aber grade über den Gegenstand schreiben und gewohnt sind in ausgedehntem Maasse die Literatur zu benutzen und zu geben, wollte ich Sie für den Fall, dass Sie die Arbeit noch nicht kennen sollten, auf ihr Vorhandensein aufmerksam machen.4

Mit dem Ausdruck ausgezeichnetster | Hochachtung | Ihr ganz ergebener | V. Hensen.

For a translation of this letter, see Appendix I.
CD’s letter to Hensen has not been found, but it was probably written to thank Hensen for sending his book, Physiologie der Zeugung (Physiology of reproduction, Hensen 1881; see letter to Francis Darwin, 27 May 1881 and n. 5). Hensen had cited several of CD’s works, including Cross and self fertilisation (Hensen 1881, p. 179). CD had studied the offspring of a particular self-fertilised plant of Ipomoea purpurea (common morning-glory) that he had dubbed ‘Hero’ owing to its prodigious growth (see Cross and self fertilisation, pp. 37, 47–51, and passim).
CD and his son Francis Darwin were already correcting proof-sheets of Earthworms, which had gone to press on 1 May 1881; it was published on 10 October 1881 (Freeman 1977).
Peter Erasmus Müller’s article ‘Studier over Skovjord’ (Studies on forest soil; P. E. Müller 1878) appeared in Tidsskrift for Skovbrug (Journal of Forestry). In Earthworms (1882), p. 8, Francis Darwin added a note mentioning that Hensen had told CD about P. E. Müller 1878, but that CD had no opportunity to consult the work.

From Victor Hensen1   25 May 1881

Kiel

25th May 1881.

Most esteemed Sir!

Just now I received your very kind letter. I could not have regretted it enough had I missed your valuable work on cross and self-fertilization of plants, fortunately it was in my possession and perhaps in time you will find even your plant “Hero” considered in the proper place.2 Actually, your works have been a goldmine of knowledge for me, as I believe the instances when I hold a significantly different opinion from one expressed by you are rare.

I look forward to your work on the earthworm with great anticipation, this is also what prompts me to reply to your kind letter immediately.3

The Danish zoologist P. A. Müller investigated the activities of the earthworm further, in Tidsskrift for Skovbrug vol III I & II issue Copenhagen 1878 in “Studier over Skovjord” (forest soil); I myself have not yet been able to get hold of this work, but since you are writing on this subject just now and are accustomed to using and citing literature extensively, I wanted to direct your attention to the existence of this work in case you did not know it yet.4

With the expression of my greatest | respect | Yours most faithfully | V. Hensen.

For a transcription of this letter in its original German, see Transcript.
CD’s letter to Hensen has not been found, but it was probably written to thank Hensen for sending his book, Physiologie der Zeugung (Physiology of reproduction, Hensen 1881; see letter to Francis Darwin, 27 May 1881 and n. 5). Hensen had cited several of CD’s works, including Cross and self fertilisation (Hensen 1881, p. 179). CD had studied the offspring of a particular self-fertilised plant of Ipomoea purpurea (common morning-glory) that he had dubbed ‘Hero’ owing to its prodigious growth (see Cross and self fertilisation, pp. 37, 47–51, and passim).
CD and his son Francis Darwin were already correcting proof-sheets of Earthworms, which had gone to press on 1 May 1881; it was published on 10 October 1881 (Freeman 1977).
Peter Erasmus Müller’s article ‘Studier over Skovjord’ (Studies on forest soil; P. E. Müller 1878) appeared in Tidsskrift for Skovbrug (Journal of Forestry). In Earthworms (1882), p. 8, Francis Darwin added a note mentioning that Hensen had told CD about P. E. Müller 1878, but that CD had no opportunity to consult the work.

Please cite as “DCP-LETT-13172,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-13172