My dear Sir.

Pray forgive my making a small suggestion, if, as I hope you try cobra poison on the white corpuscule, would it not be good for, the control experiment to have the corpuscules in a Sol: of Sugar of the same proportional strength as the cobra poison— I am led to this suggestion from what I have seen with Drosera; & I almost wish that this had been done with the vibratile cilia.—² The more I think on subject the more surprised I am at different action of the poison on vegetable & animal protoplasm.³

I forgot in my last note to thank you for your offer (if in your power) about Crotalus poison—⁴ Pray forgive me if you think my suggestion superfluous— I know well that you are a far better judge than I.— If you see D^r. L. Brunton will you tell him I am very curious to hear about the Papaw plant.—⁵ Also if he has anything more to say about the digestion of pepsine by pepsine & acid;⁶ but I suppose not.

Yours very faithfully | Ch. Darwin.