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Darwin Correspondence Project

From Anton Dohrn   7 June 1873

My dear Sir!

Your kind letter surprised me very agreeably, for though it states nothing about Your good health, it is nevertheless a sign,—I take it at least for such,—that You are not in bad health.1

I was rather ashamed, that I had written the article in “Academy”,—and Mr. Appleton needed to remind me at least three times, that I had once in a too youthful spirit promised to him to do it.2 It is generally such pretentious work, to sit down and write on a book so vastly superior to one’s own intellect and conceiving, that it strikes me often, as if it was as good or as bad as an actual lie, to do it. And thus I tried to escape as much as possible the reviewer’s duty to take on a critical habitus and scrutiny page for page to find out a point, where one might justly correct a misprint or a wrong interpunction.

I read a notice, that in the Edinburgh Review there has been a severe critic (perhaps again the infallible Mr. Mivart?) on Your new book.3 I am curious enough to see it, but as yet could not get hold of it.

I and my friends have been greatly pleased by the visit of Your son; only I regretted, that he found the Zoological Station still in such a rudimentary state.4 I am very much kept back by the negligence of the London manufacturers, who are to make the hard-india-rubber tubes: they have missed their engagement for more than four monthes, thus being the chief obstacle for me in finishing the Station.

I have been very lucky in my endeavour to win the assistance of the different governments. Not only for the 1500£. presented to me by the German Empire, but by obtaining consent for letting already seven of my Laboratory tables.5 Prussia and Italy have taken two, Bavaria one, Baden one, Cambridge one,—and negotiations are impending with Russia for two, Saxony, Alsace, Holland, Denmark and Sweden, and Belgium each one. Whether they will all succeed, I don’t know, but it is not impossible. And when they do, then I may quietly sit down, for then the Station is safe for a good time to come, and I may get back to the Microscope,—a thing which I wish very much.—

My remarks on Physiology in the article in the Academy, came out specially against Professor Ludwig and his school, who are quite absurd in their manner of treating Morphology and Evolution.6 When I met the Professor in January he told me even, that his opinion was Zoology ought to lay special stress upon technical points. I proposed then to him to change the name of this Science at once into Zootechnic,—and to remove it from the Universities to polytechnical schools. But as much as I can see, the superstition in the “exact” methods of experimental physiology is giving way a little, and it wants only a little pushing to get it down in many quarters.—7

Will you permit me to correct only one of the gross misprints, that has escaped Mr. Appleton’s correction. Just the last phrase about Spinoza’s somewhat mystical definition has been turned to complete nonsense by the one who has corrected my MSS. in changing my words “a part of what Spinoza determines” into “a part of which.”8 Besides a whole page has been wrongly placed,—but this one must be afraid of always. I would not have mentioned these points, if I could have entertained the hope, that You did not read the article.

With my kindest regards and compliments to Mrs. Darwin and Your son9 | Yours | very sincerely | Anton Dohrn

Naples. Palazzo Torlonia. | 7. June 1873.

P.S.— It will perhaps interest You as in instance of the power of genealogical investigation to read the following statement.— When occupied with the imperfect essay on the history of the Crustacean tribe, I dropped naturally upon the very puzzling group of Rhizocephala (Sacculina, Peltogaster ecc.)10 No morphology was satisfying on their structure, and though their larval states clearly indicated, that they belonged nearest to the Cirripedia, it became quite impossible to reduce them to their chief anatomical structure. It was especially perplexing to see them buried in the body of other animals with their mouth and this surrounded by those “roots”. Through Fritz Müllers investigations it became evident, that their way of nourishing themselves was to get by endosmose the fluid of the other animal into these “roots” and convey them to [lacunes] in their sac like body. Indeed it was proved by embryology, that the larvae were born without mouth and intestine! But what now with their relations to Cirripeds?11

Perhaps You remember that years ago I asked You, whether You still were in possession of a specimen of Anelasma squalicola.12 I at that time studying Your monograph was struck by the figure You gave of the peduncle of that animal, with the filaments going from it into the shark’s flesh.13 It suddenly came to my mind, that Anelasma was the passage from Cirripeds to Rhizocephala, and that those were wrong, who contended,—as universally was done,—that the Rhizocephala were attached with their mouth, and the roots came out of the mouth.14 Unfortunately I did not succeed in obtaining a single specimen of Anelasma and had to postpone the further publication of my work. Nevertheless I wrote down in MSS. all, what presented itself to my mind on behalf of this question, and argued in the following way.

Anelasma has got these filaments to fasten itself better in the shark. These filaments came to become pervaded by the blood of the shark, and this went through them into the peduncle and was at once,—digested as it was,—assimilated to the body of Anelasma. This way of nourishing was much easier than the ordinary way of Cirripeds, and thus this old way got to be abandoned. Therefore the useless extremities, that have lost their Cirriped-character, therefore the rudimentary mouth-parts, therefore the want of calcareous shell. But then, Anelasma was only half way to a complete overthrow of the Crustacean-characters. It went further. Not only the legs were completely disappearing, but even the mouth and the whole intestinal channel! Nothing remained but the body and the mantle which coalesced on the ventral side to leaving only one aperture for the ova to get out, the peduncle with the roots and the sexual glands. Thus the Rhizocephala have originated! And there is an excellent instance of the power of inheritance, for through this new mode of existence it has been effected, that already from the egg there is no more mouth, no more intestine in the young Sacculinae! This is a powerful instance to be used in quite another quarter, with which I am occupied since years.— All this was renewing itself within me, when some months ago Dr. Kossmann, a young german Zoologist came to Naples to work out the Morphology of Sacculina.15 He did not get at the solution of the Problem. Seeing his embarrassment I brought him on the right track, procured at last from Prof. Lovèn directly two Anelasma and thus after a short investigation Dr. Kossmann was able to confirm everything what I had considered as the only possible explication of the Rhizocephala-Morphology.16

I hope Dr. Kossmann will publish soon the results of this investigation.


Dohrn’s review of Expression appeared in the Academy, 2 June 1873, pp. 209–11. The Academy was a weekly review of literature, science, and art, edited by Charles Edward Cutts Birchall Appleton.
The unfavourable review of Expression in the Edinburgh Review was by Thomas Spencer Baynes (Wellesley index; see also letter to George Cupples, 28 April [1873]). St George Jackson Mivart had written several articles against natural selection (Mivart 1869, [Mivart] 1871b).
Dohrn was overseeing the construction of the zoological station at Naples (see letter from Anton Dohrn, 27 January 1873). He was probably visited by William Erasmus Darwin, who travelled to Rome in late February and who planned to visit his brothers George Howard and Horace Darwin, who were staying at Cannes from late January to March (letter from Emma Darwin to Horace Darwin, 28 [January 1873] (DAR 258: 572), letter from G. H. Darwin to Emma Darwin, [6? March 1873] (DAR 210.2: 27)).
Dohrn had approached the Prussian government for support for the zoological station, and had hoped to fund the station in part by renting out research space (see letter from Anton Dohrn, 27 January 1873 and n. 2, and Correspondence vol. 20, letter from Anton Dohrn, 13 November 1872).
See letter to Anton Dohrn, 2 June [1873] and n. 3. Carl Friedrich Wilhelm Ludwig was professor of physiology at the University of Leipzig. On his efforts to exclude questions of morphology and development from physiology, see Nyhart 1995, pp. 69–72, 82–3, 86.
The emphasis on quantitative measurement and precision instruments in German physiology is discussed in Chadarevian 1993.
The full passage to which Dohrn refers is: ‘In showing how in many cases the function of expressing emotions has its origin in other functions, he [CD] has led us to that immense and almost endless path which physiology must traverse in respect to all and every function in order to attain that point where life itself becomes but a function of matter, a part of which Spinoza determined when he said, “Cujus essentia est existentia” ’ (Academy 4 (1873): 212). The quotation attributed to Baruch de Spinoza is apparently a paraphrase of his Ethics, proposition XX: ‘Dei existentia eiusque essentia unum et idem sunt’ (the existence of God and his essence are one and the same).
It is not known which of CD’s sons Dohrn is referring to.
Dohrn had written ten papers, later collected into a book, on the structure and development of arthropods (Dohrn 1870). He had published two further papers in the series (Dohrn 1871a and Dohrn 1871b).
Müller originally classified Rhizocephala as a sister group to the Cirripedia; he had described the root-like system of Lernaeodiscus porcellanae, noting that vesicles fed into hollow channels through which a reddish fluid flowed into the central cavity where the parasite was attached to the host (F. Müller 1862, pp. 1, 4–5). CD, after reading Müller’s description in F. Müller 1864, had suggested that the pedunculate barnacle Anelasma squalicola might be a ‘beautiful connecting link’ with the Rhizocephala (see Correspondence vol. 13, letter to Fritz Müller, 10 August [1865] and n. 7). Müller later speculated, in an addition to the English translation of F. Müller 1864, that the roots were modified cirripede cement ducts and that the reduction of organs such as mouth, stomach, cirri, etc. was an adaptation to parasitic behaviour (Dallas trans. 1869, pp. 138–40).
No letter from Dohrn has been found in which he asked about Anelasma squalicola; however Dohrn may have mentioned the subject when he visited CD on 26 September 1870. Dohrn’s reminiscence of the visit is given in Heuss 1991, pp. 108–9. Dohrn had mentioned that he was working on specimens of Anelasma squalicola in his letter of 27 January 1873.
See Living Cirripedia (1851), pl. IV, figs. 2 and 3. CD told Müller that he had initially dismissed the possibility that the branching filaments of Anelasma squalicola were modified cement ducts because of the apparent continuity of the filaments with the outer membrane of the capitulum (see Correspondence vol. 13, letter to Fritz Müller, 20 September [1865] and nn. 9 and 10).
Müller had, in fact, already described adult Rhizocephala as probably lacking mouths and attached to their hosts by having their heads sunk into the host animals with chitinous rings at the attachment sites and root-like processes branching out within the hosts for the assimilation of nutrients (F. Müller 1862, p. 8).
Robby August Kossmann had written a doctoral dissertation on the anatomy of parasitic Cirripedia, later published in Arbeiten aus dem Zoologisch-Zootomischen Institut in Würzburg (Kossmann 1874a). This work focused on the genus Sacculina; in it Kossmann reverted to the earlier name of Wilhelm Lilljeborg for the group, Suctoria, having failed to find any root-like processes as described by Müller (see Kossmann 1874a, p. 102).
The results of Kossmann’s study of the specimens of Anelasma squalicola obtained from Sven Lovén were reported in his Habilitationsschrift of 1873, later published in Arbeiten aus dem Zoologisch-Zootomischen Institut in Würzburg (Kossmann 1874b). Kossmann concluded that the filaments in A. squalicola were not merely anchoring, but served a nutritive function. He also reported that he was now able to observe the root-like processes in Sacculina. Kossmann concluded with a taxonomic analysis in which he divided the family Pedunculata into two subfamilies, Lepadidae and Suctoria (ibid., p. 201).


News of Naples Zoological Station developments.

His remarks on physiology in the Academy were aimed at Prof. Ludwig and his school.

The usual "exact" methods in experimental physiology want only a little pushing to put an end to superstition.

Recounts how he had worked out the explanation of Rhizocephala morphology via the Anelasma – an example of both the power of inheritance and the power of genealogical investigation. R. Kossman’s work has now confirmed AD’s explanation.

Letter details

Letter no.
Felix Anton (Anton) Dohrn
Charles Robert Darwin
Sent from
Source of text
DAR 162: 213
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 8937,” accessed on 25 March 2019,

Also published in The Correspondence of Charles Darwin, vol. 21