To T. H. Farrer   12 July 1875

My dear Farrer

I think the experiment would be well worth trial, but it would be difficult unless D⁠⟨⁠ro⁠⟩⁠sera grew in some one’s park; for ⁠⟨⁠a⁠⟩⁠ considerable number of plants ought to be covered up very early in the season, & not fed with insects & an equal number likewise covered up & fe⁠⟨⁠d⁠⟩⁠; & an equal number of the ⁠⟨⁠pla⁠⟩⁠nts afterwards weighed, & as ⁠⟨⁠you⁠⟩⁠ justly observe their see⁠⟨⁠d⁠⟩⁠ing observed.¹ I have found that they can be easily cultivated in soup plates surrounded by moss, & the only care requisite is not to give them too much water; they like a high temperature ie cool hothouse. I had a number of plates & began your experiment last summer, but unfortunately put partitions of zinc across each plate, & this seemed to kill all the plants; any how they quickly grew so unhealthy that I could draw no conclusions.

Independantly of seeding it is not improbable that the effects of animal food might be shown on the following year.

We had a letter from my son William this morning & he ends with the following words, with which I most heartily concur “we ought really to sign a round robin of thanks of the Farrers, it was so very pleasant there”²

Believe me my dear Farrer | Yours most sincerely | Ch. Darwin

P.S | I know nothing about the fertilisation of Drosera