To Francis Darwin   16 June [1879]1

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

June 16th

My dear old F.

I like very much hearing what you & the others are doing.— I suppose Sachs wd. not care to hear but I have given my reasons in the Climbing book for not believing that the twisting of the stem has anything to do with the circumnutation: I tried several experiments on this head. Tendrils circumnutate beautifully, & do not often become twisted.—2

It is a great bore that Porliera does not act; yet I can see no reason to doubt your observations last year.3

I wonder whether “helic” & “aphelic” are classically correct.4 I despatched Photos of self in Bessy’s letter.—5

They are going to send me from Kew aerial heliotropic roots.6

My work has been almost exclusively writing. & I am now finishing Summary on Sleeping Plants, which has been excessively difficult, but the result is, I think, satisfactory & makes a good essay.7

I have done very little experimentally, but have tried a vast number of radicles of Beans, left to grow perpendicularly down, half with tips touched with caustic, & the result is that these grow wildly in all sorts of directions; but there is, alas, nothing definite about Sachs’ curvature.—8

I have begun cauterizing tips of cotyledons of Phalaris & I think(?) this acts in same manner as black caps, ie. stops basal part bending to light.9 I have been much below par of late, & work comes very hard, & sitting for that accursed picture still harder.10

Abbadubba11 is more charming than ever, but his soul is so full of drums, trumpets & soldiers that he has no time to look at me or say a word to me, but it is pleasure enough to look at his earnest sweet little face

your affectionate Father | C. Darwin

1
The year is established by the reference to experiments cauterising tips of cotyledons of Phalaris and by the reference to the picture (see nn. 9 and 10, below).
2
In Climbing plants, p. 6, CD had discussed the cause of axial twisting of the stem, concluding that twisting resulted from inequalities in the support or lack of support, and that the function of twisting was to strengthen the stem. Julius Sachs had explained revolving nutation as a result of unequal growth around the axis of the stem (Sachs 1874, p. 827).
3
No letter describing Francis’s recent work on Porliera (a synonym of Porlieria) has been found, but in his letter of 29 May 1879, Francis mentioned that the condition of some of the specimens at Würzburg was not good, but that he planned to investigate the leafstalk of two plants in pots. On Francis’s observations on Porliera in 1878, see the letter from Francis Darwin, 29 May 1879, n. 3.
4
CD was evidently considering using the terms ‘helic’ and ‘aphelic’ to denote movement towards and away from the sun, but in Movement in plants he used ‘heliotropic’ and ‘apheliotropic’.
5
The letter from Elizabeth Darwin to Francis has not been found; she left for a trip to Switzerland with a relation by marriage, Mary Elizabeth Atkin, the next day (Emma Darwin’s diary (DAR 242)). Francis had probably asked for photographs of CD for some of his Würzburg colleagues.
6
CD was sent six plants with aerial roots from the Royal Botanic Gardens, Kew, on 17 June 1879 (see letter to W. T. Thiselton-Dyer, 5 June 1879 and n. 2).
7
CD summarised his views on sleep in cotyledons (seed leaves) and mature leaves in Movement in plants, pp. 311–16 and 394–417.
8
‘Sachs’ curvature’ was a term used by CD to refer to the movement of the hypocotyl (stem supporting the cotyledon) and radicle (embryonic root) away from a perpendicular position within twenty-four hours of seed germination (see Movement in plants, pp. 91–2). The movement had first been described by Sachs in a paper on the growth of primary and adventitious roots (Sachs 1873–4, p. 403). CD’s notes on this movement in beans (Phaseolus and Vicia), dated between 4 May 1879 and 26 March 1880, are in DAR 209.6: 14–37.
9
CD’s notes, dated between 11 and 17 June 1879, describing his experiments cauterising the tips of cotyledons of Phalaris (canary grass), are in DAR 209.8: 121–2.
10
CD’s portrait was being painted by William Blake Richmond (see letter to John Fiske, 10 June 1879, n. 2).
11
Abbadubba was a pet name for Francis’s son, Bernard Darwin, who was almost 3 years old at this time.

Manuscript Alterations and Comments

6.3 alas,] above del ‘alas,’
7.1 cauterizing] above del ‘cauterising’
7.1 this] interl
7.2 stops] above del ‘stops’

Please cite as “DCP-LETT-12111,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-12111