From Hubert Airy   16 July 1872

13. Eliot Place. | Blackheath S.E.

1872. July 16.

My dear Sir

Please accept my hearty thanks for your kindness and patience in reading my pages of MS, and for the valuable suggestions you have given me.1 I must take time to reflect on what you say, and will not presume to offer any hasty remarks in this letter on the points you raise, beyond a word on one of them:—where I speak of “contraction” of the bud-axis, I do not mean a contraction taking place in the individual bud, after the axis has once been developed; but a contraction, the result of successive favourable modifications in the course of ages, from an ancestral uncontracted form. Thus the elastic cord in my mechanism represents what I suppose to have been the operation of ages of favourable modification, not of a force that takes full effect in the life-time of a single bud.— But I recognize,—and thank you for pointing out,—that the expression is one that might be mistaken, and that needs explanation.

I am very glad indeed that you have suggested the two cotyledons of Dicots. as supporting my view.—2 In the first notes that I put together on the subject, that fact stands first of all: but I was restrained from stating it in my letter to you3 by the consideration that the next leaves immediately take the crucial position in a plane at right angles to the first two. That arrangement, however, would seem imperatively required by the conditions of pressure between the first two leaves. So I shall gladly fortify my position anew with that argument.— But I will not let myself touch upon any further points at present. Only let me express my growing conviction that the true theory of phyllotaxy will be found to give most convincing illustration and proof of the great theory of Evolution.

Thank you for your very kind invitation to call upon you— I shall look forward with great pleasure to the day when I may do so, and I hope by that time I may have brought my arguments into a form more deserving of your attention.

Believe me, my dear Sir, with great respect, | Yours very truly Hubert Airy

1
CD’s reply has not been found, but see the letter from Hubert Airy, [before 15] July 1872.
2
Cotyledons: the first leaves of the embryo. Dicots: Dicotyledons, or plants of the class denoted by their possession of two cotyledons. (Jackson 1900.) Airy argued that leaf-order was most perfect in the bud, where the compact arrangement of its embryo leaves would be advantageous to a plant’s survival (Airy 1873, p. 177).

Please cite as “DCP-LETT-8414,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-8414