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.