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Darwin Correspondence Project

From Lawson Tait   2 June [1875]1

7, Great Charles St. | Birmingham.

June 2

My Dear Sir,

Dr. Burdon Sandersons paper on the leaf currents in Dionoea has set me observing the insectivorous plants, and I wait longingly for your book, that I may see more wonders.2 But some of my independant observations are most curious and one which mere accident has revealed is so startling that I hasten to send it to you, even at the risk of it being already known to you.

This afternoon I was hurriedly summoned from my plants and I left a Dionoea uncovered in a hot drawing room exposed to a full glare of sunshine

When I came back in a few hours it seemed doomed, the leaf stalks being much shrunken   Its traps were all open, so I tried to see if its nervous system were dead

I found that irritation of a nerve fibre (and we must I think give them that name) of one side of the traps caused incurvation of the fingers & closure of the flap on the opposite side only!

That is reflex action and as we find reflex action often most marked in certain forms of disease & injury which induce paralysis, it seems to me it occurs in this plant.

For instance, in health tickling the inside of the thigh does not induce elevation of the testicle by contraction of the cremaster muscle,3 save in the infant but after fracture of the spine it nearly always does. My poor dionoea, therefore, was paralysed

From what I have seen I am sure we shall find still greater reason to allow a nervous system for these plants.

I am watching a lot of my mice from whom I removed the tails at birth, and I am coming to the conclusion that the essential use of the tail there is as a recording organ, that is they record in their memories the corners they turn & the height of the holes they pass through by touching them with their tails4   Is not this queer.

With best regards to Mrs. Darwin & with tender recollections of my visit to Down,5 I remain, | Yours ever | Lawson Tait


The year is established by Tait’s references to Insectivorous plants and to his visit to Down (see nn. 2 and 5, below).
In a paper presented at the Royal Institution of Great Britain, John Scott Burdon Sanderson had described electrical phenomena associated with leaf contraction in Dionaea muscipula (Venus fly trap; see Burdon Sanderson 1874b). Insectivorous plants was published on 2 July 1875 (see CD’s ‘Journal’ (Appendix II)).
The cremaster muscle covers the testes and spermatic cord.
For more on Tait’s research on tails, see the letter from Lawson Tait, 16 March [1875] and nn. 3 and 4.
Tait visited CD on 17 April 1875 (Emma Darwin’s diary (DAR 242)).


Insectivorous plants. By Charles Darwin. London: John Murray. 1875.


Paralysis of the nervous system of Dionaea. Uses of tails of mice.

Letter details

Letter no.
Robert Lawson (Lawson) Tait
Charles Robert Darwin
Sent from
Source of text
DAR 178: 7
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 10007,” accessed on 29 November 2021,

Also published in The Correspondence of Charles Darwin, vol. 23