To Francis Darwin   18 June [1878]¹

My dear Frank

You will see by enclosed that there is poor chance of getting Ciesiskis: could you borrow it from Sachs & read it, & see whether anything concerns us, & under what circumstances the radicles bent from water?²

I have now done a good many leaves & shall do only 4 or 5 more, for all circumnutate in a plain manner, & closely like cotyledons.— I have also been observing the movements of some cotyledons & it is clear that sleep movement is nothing but exaggerated circumnutation.³

I have got an odd little fact with Oxalis: the cotyledons of O. Valdiviana rise vertically up late in evening, whilst those of O. rosea & floribunda sink vertically down. There is something very odd about the hypocotyl of O. rosea; if tied with a thread to a pin or very thin stick, or if tied to nothing, it makes both cotyledons to sink downwards in a marked manner, but I must experimentise more about this odd transmitted sensitiveness.⁴

Radicles have been going very badly, neither decidedly negative nor positive; & this is an odious state of things.⁵

I hope in a fortnight to have done with spontaneous movements, & then must begin on light.—⁶ This work, with no writing, I find very wholesome, but very tiring.

Bernard⁷ lately has had many servile admirers & he is as charming as charming can be.—

Your affect Father | C. Darwin

Could you easily go at night into Botanic garden green House or Hot House & look out for sleepers?⁸