Dear Sir!

Your letter adressed to Heidelberg was delivered there to my wife and so I received it some days ago at Munich.² As You are kind enough to take an interest in our doings I schall give You some details of our common plans. My brother³ book now a leave from Russia for 18 months and is now in the position of a boy before the long vacation not knowing how to make the best of it; he intended to go to Naples or Cherso⁴ to finish the developement of the Bonelia commenced two years ago, but not finished as it was not the season of developement. The thing is very interesting (if his conclusion about the supposed males is correct), as it present us with such a complete dimorphism, the male and female at first glance seeming to belong to diferrent groups or even classes of worms. As it may interest You, and the little notice of it is printed in Russian I send You the Plate and some explanation.⁵ You certainly know the very interesting paper of Lacase Dudier in the Annales des Sciences Natur. on the Bonelia and the splendid figures given there,⁶ Lacase had in hands about a hundred Bonelias, but always females; Smarda who also wrote an article about these Sipunculidae⁷ could never detect a male, so was it the first time with my brother; he found at a lucky place a whole colony of Bonelias, but all were females and after mutilating hundreds he gave it away in despair; but returning to the same place in September 68 and beginning a new massacre he saw in the outer bag or infundibulum of the sexual organ of the animal (female) in every specimen some strange planarias, very small, from 2 to 7 in every female. They were covered with cilia and seemed quite like Small Turbellarias with a white patch or line in the centre, this white line contained spermatazoa. As at this special period literarly every female had these planarias living in her sexual organs there is great probability that they are the males. If the case will stand future investigation it will certainly be one of the best instance of dimorphism, the female being a Sipunculus and the male a Planarian like animal; so as I said his intention was to go to Naples, but as it seems he changed his mind and intends to go to a new place where no naturalist worked before, the little bay is called Thor and lays on the Sinai peninsula not very far from Suez, facing rich coral reefs. I, for my part am against his undetaking the journey before October, as in the summer the pilgrims going from Africa to Mekka generally bring with them pest, cholera and what not.—⁸

My wife wished to go to Berlin, and the Rector the know physiologist Dubois Reymond⁹ was one of our advocates, and a better one is difficult to have, but the matematicians were against it, holding to the strict sense of the law. Generally the matematicians are the worst thing living, not only in Germany but also in our country and I hope in England. One of the principal opponents to the admission of ladies was Kunt,¹⁰ a true pure, who at one of the Natural Science Congress proposed a toast “for the theory of numbers (Zahlenteorie) as a part of mathematics that till the present was not besmeared with practical application”. So are they all, more or less. But happily Kirchhow took a great interest in her and promised to give her a special investigation about light in the summer, so she remains a suer at Heidelberg.¹¹ For my part I am quite incertain what to do, going to Vienna and working with the assistance of Tehermak and Suess,¹² or going to England and working alone whithout direction. I think I’ll take the latter course; firstly because with Your kindness to me I will have as good assistance as can be; scondly because I will have the use of the best collections existing.—

The one point which most interest me is, can I have trough a member the use of the Library of the Geological Society, not only reading there, but taking the books out to my lodging as my principal workink time is in the night. I think I shall take the liberty to write about this point to M^r. Huxley, as the free use of the Library is one of the Chief point which determine my going to London.—¹³ The vacation commences this Sunday, and Monday I hope to break off and go to Nizza with my wife and one of her friends, a young lady about her age but “learned in the law”, as she is pursuing now law studies at Heidelberg.¹⁴ What will Your ladies say of such an ultra blue stocking.

The principal attraction of the coast of Nizza for me is the rich fauna of mollusks, the splendid series of deposits from the trias to the upper Chalk and especially the wonderful new Wealden, only not of the Jurrasic but of the Upper Cretaceous period with a developement of 600 feet of freschwater sediments and lignites, at least so is it affirmed by Coquand and I am very restless to see the wonder with my own eyes and especially to collect and study its fauna.¹⁵ In case You write me, please to adress Nizza, poste restante. With Your permission I write You from Nizza.— My compliments to M^rs. Darwin and the ladies

Yours very truly | W. Kowalevsky

Munich | 28 February