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Darwin Correspondence Project

To Francis Darwin   30 [May 1876]1


Monday 30th

My dear F.

You cd. make aggregation less intense by using much weaker sol. of C. of Ammonia; or by putting minute splinters of glass on glands.2

If your case of Teazle holds good it is a wonderful discovery. Try whether pure water or weak infusion of raw meat will bring out the protoplasmic masses.3 The closest analogy seems to me that of an independent Amœba or Foraminiferous animal &c which feeds by involving at any point of its gelatinous body particles of organic matter & then rejecting them— A mass of rotting insects would give such particles.— Perhaps this is your view. But I do not understand what you mean by a resinous secretion becoming slimy, or about living insects being caught. I would work at this subject, if I were you, to the point of death.4

If an Amœba-like mass comes out of cells & catches dead particles & digest them, it wd. beat all to fits true digesting plants.

I never saw anything come out of quadrifids of Utricularia & I cd. hardly have failed to see them, as I was on look out for secretion.5 It wd be a grand discovery. Could you chop up or pound excessively fine raw meat, or better 12 decayed meat & colour the particles first, & then you cd see them in the protoplasmic masses; for surely you could hardly expect (unless there is a distinct hole) that they shd. be withdrawn within cells of glands.— The case is grand—

Are any orifices or orifice visible in cut-off summit of gland? For heaven sake report progress of your work.—

I see in last G. Chronicle another man denies that Dionæa profits by absorption & digestion, which he does not deny.6 It seems to me a monstrous conclusion— But this subject ought to be investigated   Especially effects on Seed-bearing— Teazles good. for this—

Yours affecly— | C. Darwin

No doubt marginal glands of Drosera answer to glands on serratures of other leaves. Probably glands wd. be found on apices of spikes of Dionæa in bud-state.7


The month and year are established by the relationship between this letter and the letters from Francis Darwin, [28 May 1876] and [29 May 1876]. CD evidently wrote ‘Monday’ in error; 30 May 1876 was a Tuesday.
CD’s advice was in response to Francis Darwin’s complaint about aggregated protoplasm forming motionless masses (see letter from Francis Darwin, [29 May 1876]). CD refers to a solution of carbonate of ammonia.
Francis had discovered that protoplasmic filaments protruded from the glandular hairs lining the cups of the common or fuller’s teasel (Dipsacus sylvestris, a synonym of D. fullonum). See letter from Francis Darwin, [28 May 1876] and n. 3.
See letter from Francis Darwin, [28 May 1876] and n. 3. An amoeba was considered to be a small mass of undifferentiated protoplasm. Foraminifera are unicellular marine protozoans; they are typically found near the bottom of the sea (Lipps et al. 2011). In his printed paper, Francis described the filaments as having a ‘gelatinous consistence’ (F. Darwin 1877b, p. 248).
The quadrifids of Utricularia (bladderwort) are four divergent arms in the bladders (see Insectivorous plants, pp. 402–4).
There was a brief note on Dionaea muscipula (Venus fly trap) in Gardeners’ Chronicle, 27 May 1876, p. 689.
See letter from Francis Darwin, [28 May 1876] and n. 4. Drosera is the genus of sundews.


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


Discusses FD’s observations on the protrusion of protoplasmic masses by cells of the teasel. Suggests analogy with amoeba. "I would work at this subject if I were you, to the point of death."

Letter details

Letter no.
Charles Robert Darwin
Francis Darwin
Sent from
Source of text
DAR 271.3: 14
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 10517,” accessed on 21 July 2024,

Also published in The Correspondence of Charles Darwin, vol. 24