To Daniel Oliver 17 October 
15 Marine Parade | Eastbourne
My dear Sir
I am infinitely obliged for your mass of interesting facts & extracts.—1 The only at all full account which I have seen of Dionæa is by Mr Curtus, quoted by author (Lindley?) in Penny Encyclopædia.2 Lindley also refers to Dionæa having been fed & flourished on chopped meat.— I think you could see with lens on growing plant whether colour in Sensitive Hairs becomes broken after being touched; that experiment & effect of C. of Ammonia on disc could be very interesting. A good dissector, I daresay could follow the cells with red matter from base of sensitive Hair, & thus follow its nerves!—
Many thanks about stomata; it was uncommonly stupid in me not to think of your explanation, which I have hardly a doubt is right;3 for it was after removing the tortoise-like glands, which are mounted on very short footstalks, that I saw the appearance of stomata: I have hardly a doubt that my so-called stomata are 2 cells of the footstalk.—
Thanks for your various analogies & comparisons about the moving red matter: it is beyond me; I shall just publish what I saw.—4 I think that you have misunderstood me in supposing that this appearance follows only from C. of Ammonia.— it is better seen in the Hairs which have naturally contracted over a fly or other object; & this it is, which seems to me to make the case curious.— I have been ascertaining this morning how quickly C. of Ammonia acts; & certainly 13 seconds suffice for the absorption & for a marked change in structure in the glands; in one minute the action reaches the upper part of footstalk.— No other substance (such as Acetate, Oxalate, nitrate of Ammonia &c &c) acts nearly so quickly, though they do act after some time; the acetate of Ammonia is next in quickness.— I suspect that milk, urine &c & these salts do not act until they have become decomposed, & yield C. of Ammonia.— I cannot avoid suspecting that we see in the action of these substances on the leaves of Drosera what chemists believe takes place with organic manures on the roots of other plants.—5 I am going to try tomorrow C. of Ammonia on the root of Drosera & on some other common plant.—6
Thanks about Elatine—& for Goodenia Plants.— Pray thank Croker7 for all great trouble which he has taken.—
I have told Murray to send you copy of my Journal,8 which I am very glad you did not possess.—
Yours very truly | C. Darwin
The day after tomorrow I shall begin & draw up my paper on Drosera; for I have wasted a shameful lot of time on it—& yours also.9
The leaves of D. spathulata will not open.—
Thanks for information and extracts.
M. A. Curtis, quoted in ["Dionaea"] Penny encyclopedia [(1837) 8: 508], gives the only full account of Dionaea.
Concurs in DO’s explanation of Dionaea footstalk cells, which CD took for stomata.
Is using carbonate of ammonia as a substitute for flies and colour change in glands as index of action on Drosera. Suspects other nitrogenous compounds do not act till decomposed into carbonate of ammonia. Beginning to write Drosera paper. Action of nitrogenous compounds.
Please cite as
Darwin Correspondence Project, “Letter no. 2951,” accessed on 20 October 2016, http://www.darwinproject.ac.uk/DCP-LETT-2951