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Darwin Correspondence Project


From T. H. Farrer   5 November 1869

The Athenæum

5 Nov /69

My dear Mr Darwin,

If you will put questions “no fellah can answer”, you at any rate bear patiently the infliction of guesses.

Here is one at Mimosa.1 The petioles are long and slender; and a considerable surface of leaf is exposed. A puff from the mouth makes the leaflets fold and the leafstalk bend down much more universally and thoroughly than a touch with the fingers or a sprinkle with water.

Now what if the motion should be a protection against storms of wind. On the first blast the prudent plant not only reefs and furls, but also lowers its sails and makes all snug against the coming storm!!

How and where the plants grow: what is their size and mode of life; in short all that one wants to know wholly fails to appear in the big books at the Linnean.2

I have a Passiflora princeps though an imperfect one.3 You are quite right that there are five corners in the process4 towards the base of the inner corona which leave apparently large apertures towards the nectary. But the upper part of this corona is so closely applied to the column that a straight object can only go straight down and then it is sure to go—not into the nectary, but into the angle between the column and the innermost process—(qu innermost corona) and to be caught there


Sincerely yours | T H Farrer

C Darwin Esqr FRS


No query to Farrer regarding Mimosa has been found. CD later observed and published on several Mimosa species (see Movement in plants).
Farrer refers to the library of the Linnean Society of London.
In his letter of 20 October [1869], CD suggested that Farrer observe the flower structure of Passiflora princeps (now P. racemosa, the red passionflower).
Process: an outgrowth (OED).


Sends a "guess" about Mimosa leaf structure as an answer to one of CD’s questions.

Has found a Passiflora princeps.

Letter details

Letter no.
Farrer, T. H.
Darwin, C. R.
Sent from
Athenaeum Club
Source of text
DAR 164: 60
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 6973,” accessed on 28 October 2016,