To Ernst Haeckel 30 March 1
Down Bromley Kent [4 Chester Place]
My dear Friend
I am much obliged for your interesting letter with its genealogical tree.2
I now understand to a certain extent the importance of the swim-bladder in the Selachians.3 I shall be curious to see whether the organ ought not to be considered rather in a “nascent” than in a “rudimentary” state. I had always imagined that some animal like the Lepidosiren was the parent-form of the Vertebrata.—4
By all means keep the German edition of my Book: it will be of far more use in your hands than in anyone’s else.—5
We have been staying nearly a month in London & I am as wearied of the din & turmoil of the place, as you could be; but we return in two days to the quietude of Down.6 My visit here has not been one of rest, for I have been hard at work in collecting new facts on Sexual selection, by corresponding with a multitude of breeders & visiting them & the zoological Gardens.
This subject will be the chief one in my next little book, for I entirely agree with you that sexual selection has played a most important part with man.7 But I find many very serious objections & difficulties & shall not make out a very good case.—
I am astonished at the hybrids of Hare & rabbit: is it certain that Dr Conrad began his work with a true wild Lepus timidus & not with a hare-like var. of the L. cuniculus?8
I am tired with writing letters, so will write no more, & will conclude with my unalterable esteem & friendship.—
Yours very truly | Ch. Darwin
Now understands importance of swim-bladder in selachians. Always imagined animal like Lepidosiren was parent form of vertebrates.
Has been nearly a month in London, collecting facts on sexual selection from breeders and at Zoological Gardens.
Astonished at hybrid of rabbit and hare. Is it certain that work was done with hare?
Please cite as
Darwin Correspondence Project, “Letter no. 6070,” accessed on 23 March 2017, http://www.darwinproject.ac.uk/DCP-LETT-6070