To Ernst Haeckel 6 December 
Down Bromley | Kent
My dear Sir
I am much obliged for your last letter of Nov. 11., for your letters always give me pleasure.1 I am not surprized at the delay in the publication of your book, more especially as you are appointed Professor & have been doing other work.2 I shall feel much interest in seeing this book when it appears. I most sincerely wish that you could work with better spirits; but time in the long run will do something for you.3
With your lectures & various writings, no one I think will do so much as you in spreading & perfecting sound views on species in Germany.4
Every now & then I find some good young worker taking the same side in England; I have just found this is the case with one of our best rising paleontologists Dr Duncan.5 I occasionally hear from Max Müller in Desterro & he seems to be grandly in earnest on the subject.6
You tell me that you have sent me a book with plates on Medusæ & on fossil Medusæ & on some Rhizopods, but I have not received these.7
I have received only a description of new “Craspedoter medusen” from Nice, & the Monats bericht of Berlin on the generation of the Geryoniden &c8
This latter paper interested me & surprized me much for I have often speculated whether any such case did occur in Nature & thought it possible, but never expected to see it proved.9 I suppose the paper with plates is on this same subject.10
I am sorry to say I can give but a poor account of my health: since April I have been able to do no scientific work, nor do I see any probability of any near approach to such happy days.11
With the most sincere respect & good wishes believe me my dear Sir yours very sincerely | Ch. Darwin
Not surprised at delay of his book [Generelle Morphologie (1866)].
P. M. Duncan taking side of evolution.
Has received paper on Geryonidae ["Über eine neue Form des Generationswechsels bei den Medusen", Monatsber. K. Akad. Wiss. Berlin (1865): 85–94]. Had often speculated on whether such a case ever occurred in nature.
Please cite as
Darwin Correspondence Project, “Letter no. 4947,” accessed on 25 September 2016, http://www.darwinproject.ac.uk/DCP-LETT-4947