My dear Sir.

I am extremely much obliged for your letter; which I can compare only to a plum pudding, so full it is of good things.—   I have been rash about the Cats; yet I spoke on what seemed to me good authority: the Rev^d. W. D. Fox gave me a list of cases of various foreign breeds in which he had observed the correlation & for years he had vainly sought an exception.² A French paper also gives numerous cases, & one very curious one of a kitten which gradually lost the blue colour in its eyes & as gradually acquired its power of hearing—³ I had not heard of your uncle M^r Kirby’s (whom I, for as long as I can remember have venerated) care in breeding cats—⁴ I do not know whether M^r Kirby was your uncle by marriage; but your letters show me that you ought to have Kirby-blood in your veins, that if you had not taken to languages you would have been a first rate naturalist.

Your Rat case is most wonderful—   It is hardly fair to ask you to take so much trouble; but I should be very much obliged for a little more information—   Did the workmen believe that they were blind? Might it not have been that they were temporarily blinded by being brought suddenly into bright light? Do you remember whether there was any difference in the eyes besides the paleness? Was the appearance of the eyes sufficiently remarkable to excite attention in others? Lastly might I quote your name as my authority—⁵ I have been so attacked that I am sure you will not wonder at my requiring to give authorities & all evidence that I can. D^r. Bree, for instance, who has just published a Book against me, speaks with utter contempt of my statement about colour & the action of poison; & logically engages to poison a white & black sheep or pig with the same poison!⁶ Probably he would select arsenic!

Your case about the Rats interests me especially, because in some French Transactions, there is a long account of some eels taken out of a deep & dark artificial well, which were stone blind & had singularly shaped heads;⁷ but these fish were pronounced by Agassiz to be the common species.⁸

Very many thanks for information about horses;⁹ My memory has returned so far that I believe I can trace in Heusingers German Pamphlet¹⁰ where I have read an account in some English Book (certainly not in my old friend L. Jenyns books)¹¹    I feel almost sure the result followed from eating “lousy tares” but whether Horses or Cattle I cannot remember.—   Your case will be a most valuable confirmation— I sincerely hope that you will be able to carry out your intention of writing on the “Birth Life & Death of Words”. Anyhow you have a capital Title, & some think this the most difficult part of a book.—   I remember years ago at the C. of Good Hope; Sir J. Herschel saying to me—I wish some one would treat language as Lyell has treated Geology—¹² What a Linguist you must be to translate the Koran!¹³ Having a vilely bad head for languages—I feel an awful respect for Linguists.—

I do not know whether my Brother in Law Hensleigh Wedgwoods, Etymological Dict^y would be at all in your line; but he treats briefly on the genesis of words, & as it seems to me very ingeniously—¹⁴

You kindly say that you would communicate any facts which might occur to you; & I am sure that I should be most grateful—   Of the multitude of letters which I receive not one in a thousand is like yours in value—

With my cordial thanks & apologies for this untidy letter written in haste | Pray believe me, My dear Sir. Yours sincerely obliged. | Ch. Darwin.

We are delayed here by most suffering illness of my daughter but we hope to return to “Down, Bromley, Kent” in about a weeks time.