To J. D. Hooker   1 July [1857]1

Down Bromley Kent

July 1st

My dear Hooker

I write to say how truly I think you the best of men for proposing to pay us a visit this summer, I shall most truly & heartily enjoy it. In a few weeks time we shall know our plans better, as Etty & our Boys holidays make everything doubtful I am alone at present Emma visiting some relations with a tail of six children!2 I am very sorry to hear about G. Henslow: an attack of religion is a most serious thing: the whole affair must be a great disappointment to you.—3

Thanks for your interesting note about embryonic leaves: after I had sent it, I began to think about cotyledons, & marvelled that I could not remember having ever read any discussion on their resemblances & dissimilarities in allied plants. How curious that the subject shd never have been taken up! I do not even know whether functions of the cotyledons are same as leaves, or whether they serve, also, as receptacle of nutriment: I have noticed in my weed-garden that their destruction seems always to kill the plant.— I was speculating in my ignorance that the form of cotyledon was probably related to the shape of seed & its embryo & radicle; & if this were so, as seeds are adapted to various contingencies, we might expect the cotyledons to differ; but probably this is not the case, as it wd. have occurred to you. I am not learned enough in animal embryology to compare cotyledons with amnios &c &c.—

If cotyledons have a relation to the external conditions of existence distinct or partially different from what the leaves of the mature plant have to the conditions, I think the differences of the cotyledons in the same Family, would be explicable in the same way as in some Diptera & some Neuroptera, there is a wonderful amount of difference in the larvæ:— no doubt these larvæ have much in common, & so I presume the cotyledons have much in common.

I have had another letter from Asa Gray: most kindly he has worked out trees of U. States & finds out of 132, 95 have sexes more or less separate (= .72); so that the Rule seems here to hold good whether or no my explanation is correct.4

Farewell | My dear Hooker | Ever yours | C. Darwin

1
The year is established by the subjects discussed and by CD’s reference to Emma Darwin and the children being away from Down (see n. 2, below).
2
Emma and the children were visiting Francis (Frank) Wedgwood and his family in Barlaston, Staffordshire. They later travelled to Shrewsbury, the children returning to Down on 4 July 1857 and Emma on 6 July (Emma Darwin’s diary).
3
The missing portion of the letter from J. D. Hooker, [27] June 1857 may have discussed this point.

Manuscript Alterations and Comments

1.1 the] over ‘are’
1.2 summer,] comma over full stop
1.3 make] after del ‘pu’
1.6 affair] interl
2.2 that] interl
2.11 in] after del illeg
3.1 relation] after del ‘more distinct’
3.1 distinct] after del ‘than have true leaves’
3.2 of the mature] after del ‘have’; ‘of’ over ‘to’
3.2 have to the conditions,] interl
3.3 the] altered from ‘these’
3.3 of the cotyledons] interl

Please cite as “DCP-LETT-2116,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-2116