My dear Darwin

Alas! alas!— and I had taken such pains to express myself clearly, and I see what I mean, so clearly!—¹

I was most obliged for the Brown-Séquard reference in the Lancet, & will certainly alter the paragraph. His non-publication of the paper even in abstract read by him at the Brit. Assocⁿ. in 1870, had given me additional fear that there was something wrong.²

All the other points you refer to in your letter, I will do what I can, about:— viz:– make clearer, answer, or amend; but it is too late to make more than small alterations in the proof.

Thank you for reference & offer to send Panum, but I have a description of his results, so far as I want them, in C. Dareste (Ann: Sc: Naturelles 1862 sur les œufs à double germe p.34.³

In my ‘Fraser’ article, there is a most unlucky & absurd collocation of words, which I heartily hope no critic will seize upon, for which I simply ca’nt account except in the supposition of badly scratching out in the MS & variously altering some passage   It is about “double yolked eggs” & “single germs”. I ought never to have passed it in proof; but there it is.⁴

That twins born in one chorion:— never mind whether 2 ammions or not,— is Kleinwächter’s dictum which he fortifies by numerous modern German authorities.⁵ Kiwisch⁶ being the only one who, it appears, still talks of fusion of membranes. I also noted the remark in the Catalogue of the Museum Coll: Surgeons “Teratology” that twins in one chorion are probably (I think that was the word) derived from 2 germinal spots on one ovum.⁷

If you care to see Kleinwächter, I could send it you.

Very sincerely Y^rs | Francis Galton