My dear Galton.—

I have read your essay with much curiosity & interest, but you probably have no idea how excessively difficult it is to understand.² I cannot fully grasp, only here & there conjecture, what are the points on which we differ.— I daresay this is chiefly due to muddy-headiness on my part but I do not think wholly so.— Your many terms not defined, “developed germs”—“fertile” & “sterile germs” (the word “germ” itself from association misleading to me) “stirp”—“sept” “residue” &c &c quite confounded me.³ If I ask myself how you derive & where you place the innumerable gemmules⁴ contained within the spermatogen formed by a male animal during its whole life I cannot answer myself.— Unless you can make several parts clearer I believe (though I hope I am altogether wrong) that very few will endeavour or succeed in, fathoming your meaning.

I have marked a few passages with numbers,⁵ & here make a few remarks & express my opinion, as you desire it, not that I suppose it will be of any use to you.—

(1) If this implies that many parts are not modified by use & disuse during the life of the individual, I differ widely from you, as every year I come to attribute more & more to such agency.

(2) This seems rather bold, as sexuality has not been detected in some of the lowest forms, though I daresay it may hereafter be.

(3) If gemmules (to use my own term) were often deficient in buds I cannot but think that bud-variations w^d be commoner than they are in a state of nature: nor does it seem that bud-variations often exhibit deficiencies which might be accounted for by absence of the proper gemmules. I take a very different view of the meaning or cause of sexuality.

(4) I have ordered Fraser’s Mag. & am curious to learn how twins from a single ovum are distinguished from twins from 2 ova.⁶ Nothing seems to me more curious than the similarity & dissimilarity of twins.—

(5) Awfully difficult to understand.

(6) I have given almost the same notion.

(7) I hope that all this will be altered. I have received new & additional cases, so that I have now not a shadow of doubt.—⁷

(8) Such cases can hardly be spoken of as very rare, as you w^d say if you had received half the number of cases which I have.—

I am very sorry to differ so much from you but I have thought that you w^d desire my open opinion.— Frank is away; otherwise he sh^d have copied my scrawl.

I have got a good stock of pods of Sweet Peas, but the autumn has been frightfully bad; perhaps we may still get a few more to ripen.⁸

My dear Galton | Yours very sincerely | Ch Darwin