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Darwin Correspondence Project

From Lawson Tait   21 July [1875]1

7, Great Charles St. | Birmingham.

July 21

My Dear Sir,

I did try the water of unopened pitchers on flies, but they grew fungus immediately; so that the conclusion, though negative, is against the presence of the ferment in quantity enough to prevent growth.2 This it most certainly does prevent when in the pitcher, for I have removed & examined insects in all stages of digestion from pitchers, but have found neither bacteria nor fungus   Bacteria flourish, however within the closed leaf of the Dionoea3

This perfectly harmonises with my finding only a trace of the substance separated by my process from fluid taken from unopened pitchers

I shall add this when I see proof.4

One other matter of great interest. Two of my plants which I have been feeding have put out plantlets(?) from the middle of the discs of leaves.

This is parthenogenesis as seen in ferns which are overfed! This is singularly corroborative of my theory of dermoid tumours of the ovary which I brought under your notice5

This is a matter I should like to work up, for though hypo-erchitic efforts (arrest of developement) have been exhaustively discussed, hyper-erchitism (transcendent developement) has been wholly overlooked.6

I send you a slide with one of these leaves   Can you give me any hints about it? I beg however that you will not put yourself to inconvenience to do so.

I trouble you with the slide as I am sure it will interest you. May I ask you to return it as it is the best I have. I shall mount another for you if you care to have it

Yours, Lawson Tait

P.S | You will see that one of the leaves of the plantlet has caught a spider.

I also enclose the only specimen of Droserin from Drosera binata which I have

In the watch glass is some Droserin separated yesterday from the active secretions of Nepenthe pitchers.7 Naked eye appearances are almost conclusive that they are the same & their actions are, so far as I can see, identical

If you care to try anything with the contents of the watch glass I shall be glad that you should use it

I should like the little bottle & its contents back.

Yours faithfully | Lawson Tait

Or if you care to do so send the watch glass to Dr. Hooker.8

I have just read proof for the Spectator I hope you will like it.


The year is established by the reference to Tait’s review in the Spectator (see n. 4, below).
CD had advised Tait to test the digestive powers of fluid in Nepenthes (the tropical pitcher-plant) that had not been exposed to animal matter (see letter to Lawson Tait, 20 July [1875]).
Dionaea muscipula: the Venus fly trap.
The proof was for Tait’s review of Insectivorous plants in the Spectator, 14 August 1875, pp. 784–5.
On Tait’s theory of erchitism, see the letter from Lawson Tait, 17 March [1875] and n. 4.
Tait gave the name ‘droserin’ to a substance he extracted from the tropical pitcher-plant, Nepenthes (see letter from Lawson Tait, 15 July [1875] and n. 5). A watchglass is a shallow glass receptacle used in chemistry and microscopy (OED).
CD had previously informed Tait that Joseph Dalton Hooker was working on the digestive properties of Nepenthes (see letter to Lawson Tait, 17 [July 1875]).


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

OED: The Oxford English dictionary. Being a corrected re-issue with an introduction, supplement and bibliography of a new English dictionary. Edited by James A. H. Murray, et al. 12 vols. and supplement. Oxford: Clarendon Press. 1970. A supplement to the Oxford English dictionary. 4 vols. Edited by R. W. Burchfield. Oxford: Clarendon Press. 1972–86. The Oxford English dictionary. 2d edition. 20 vols. Prepared by J. A. Simpson and E. S. C. Weiner. Oxford: Clarendon Press. 1989. Oxford English dictionary additional series. 3 vols. Edited by John Simpson et al. Oxford: Clarendon Press. 1993–7.


Insectivorous plants: observations on the digestive fluid of Nepenthes.

Reproduction of plant by "parthenogenesis".

Letter details

Letter no.
Robert Lawson (Lawson) Tait
Charles Robert Darwin
Sent from
Source of text
DAR 178: 16
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 10086,” accessed on 2 August 2021,

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