My dear Sir

Pray accept my ⁠⟨⁠    ⁠⟩⁠ for your very kind l⁠⟨⁠    ⁠⟩⁠ for the help you give m⁠⟨⁠    ⁠⟩⁠ learning something about ⁠⟨⁠ph⁠⟩⁠yllotaxy. Nägeli’s observa⁠⟨⁠tion⁠⟩⁠ seems to be a⁠⟨⁠n⁠⟩⁠ important one; and, if borne o⁠⟨⁠ut⁠⟩⁠ by the facts, will make rather for tha⁠⟨⁠n⁠⟩⁠ against my view, I conceive.¹ For I ⁠⟨⁠sh⁠⟩⁠d suppose (till I find his own ⁠⟨⁠wo⁠⟩⁠rds) he means that the bud in its earliest dissect-able condition—in the summer—has its emb⁠⟨⁠ryonic⁠⟩⁠ leaves in some disorder and gradually acquires an orderly arrangement as it swells into the full winter-bud. This would certainly favour my view, that the orderly arrangement is due t⁠⟨⁠o⁠⟩⁠ the need of economy of space, ⁠⟨⁠  ⁠⟩⁠ng especially felt when ⁠⟨⁠    ⁠⟩⁠ leaves are swelling a ⁠⟨⁠    ⁠⟩⁠ta the autumn. As far as ⁠⟨⁠my⁠⟩⁠ observations go, ⁠⟨⁠the⁠⟩⁠ young le⁠⟨⁠aves ar⁠⟩⁠e arranged in perfect order in the ⁠⟨⁠win⁠⟩⁠ter-bud, and I have often found it easy to determine the leaf-arrangement in the bud, when it was most difficult to d⁠⟨⁠o⁠⟩⁠ so in the developed twig, on ac⁠⟨⁠cou⁠⟩⁠nt of unequal twists in ⁠⟨⁠the⁠⟩⁠ internodes. My attempts ⁠⟨⁠at⁠⟩⁠ dissection of summer-buds (⁠⟨⁠    ⁠⟩⁠ hiding at the base of the green leaf) h⁠⟨⁠ave⁠⟩⁠ not been successful.

We might look for evidence from embryology, in leaves as in animals. —May we regard the axillary bud as a kind of parthenogenetic ovary of the leaf to which it belongs?

Let me thank you f⁠⟨⁠or⁠⟩⁠ your k⁠⟨⁠ind⁠⟩⁠ offer to lend me M^r Wright’s ⁠⟨⁠p⁠⟩⁠aper when you have i⁠⟨⁠t a⁠⟩⁠t liberty²   I shall be very glad indeed to see it. I heard the Rev. G. Hensl⁠⟨⁠ow⁠⟩⁠ deliver a lecture on Phyll⁠⟨⁠otaxis⁠⟩⁠ at the Victoria Institute i⁠⟨⁠n⁠⟩⁠ the early part of the year.³ It was a capital exposition of the ⁠⟨⁠pur⁠⟩⁠ely mathematical and mystic ⁠⟨⁠v⁠⟩⁠iew, but that was just what I ⁠⟨⁠had⁠⟩⁠ lately escaped from, and I ⁠⟨⁠wa⁠⟩⁠s not satisfied. He made m⁠⟨⁠uch⁠⟩⁠ of a few irregularities (notably ⁠⟨⁠    ⁠⟩⁠ to be fou⁠⟨⁠nd in⁠⟩⁠ the stem ⁠⟨⁠of⁠⟩⁠ the Jer⁠⟨⁠usalem⁠⟩⁠ artichoke) ⁠⟨⁠    ⁠⟩⁠ ⁠⟨⁠see⁠⟩⁠med to be unacquainted with ⁠⟨⁠in⁠⟩⁠stances of regular irregularity su⁠⟨⁠ch⁠⟩⁠ as that in Spanish che⁠⟨⁠stn⁠⟩⁠ut.⁴ It is curious to see how the same tree will sometimes affect different leaf-orders in different shoots. The laurel, for instance⁠⟨⁠,⁠⟩⁠ has two ranks of leaves on its latera⁠⟨⁠l⁠⟩⁠ twigs, but you w⁠⟨⁠i⁠⟩⁠ll ⁠⟨⁠o⁠⟩⁠ften find ⁠⟨⁠a⁠⟩⁠ healthy leading-shoot with five. The same is the case ⁠⟨⁠with the     ⁠⟩⁠ nut and the ivy.⁵

⁠⟨⁠    ⁠⟩⁠ will remember the platysma against the next shivering fit I see or feel.⁶

With many thanks I remain | My ⁠⟨⁠de⁠⟩⁠ar Sir | Yours very sincerely | Hubert Airy

Charles Darwin Esq^re. F.R.S.