My dear D^r Sanderson

I am going to beg a great favour of you, viz. to read over the enclosed brief abstract of the results of certain experiments on Drosera;¹ & then to answer 3 or 4 questions, & to consider whether you can suggest any other soluble substances which it w^d be well worth my trying.

I do not wish to try many more, as I hardly know whether these results are worth much, & I do know that I have not sufficient knowledge. Drosera is highly peculiar by possessing absorbent glands on the leaves, & by shewing thro’ the inflection of the tentacles, the influence of certain fluids.

It will be well to explain how the enclosed results were obtained: I place half a minim of the solution on the glands of the disk of the leaf; & when I speak of “inflection”, I always mean that the circumferential tentacles have become inflected, tho’ their glands have not absorbed any of the fluid: the circumferential tentacles are caused to move by the stimulus transmitted from the glands of the disk. My object in the experiments here referred to, has been to ascertain how far those soluble substances which produce any strongly marked effect on animals, likewise affect Drosera: fluids which actually corrode the tissues seem to me unimportant. My queries are appended to the enclosed results & are marked with red lines, so as to catch your attention.

You will confer a very great kindness on me, if you will advise me ever so briefly, or make any suggestions. It will perhaps save you a little trouble to write any remarks on the back of my pages.

Pray forgive me for asking this favour, which I fear is somewhat unreasonable, & believe me | yours very sincerely | Ch. Darwin

I was very glad to read your article in last Nature.—²