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Darwin Correspondence Project

To Francis Darwin   [1 June 1876]1

[Hopedene, Surrey.]

My dear F.

I cannot help thinking of your discovery—if it proves so, but do not be too much disappointed if it fails—all day long.— It will be curious if the movements of the protoplasm depend on the excitement of ammonia or nitrogeneous matter.2 It will be very important to ascertain whether it can be withdrawn, or whether it oozes out through walls of cells & remains permanently extruded. Would an atom of acetic acid or alcohol or osmic acid cause withdrawal.

C. D.


Take care and do not overwork and kill the goose that lays the golden eggs.—


The date is established by the relationship between this letter and the letter from Francis Darwin, [28 May 1876]. The Thursday after 28 May 1876 was 1 June.
Francis had discovered protoplasmic filaments protruding from the glandular hairs in the cups of the common or fuller’s teasel (Dipsacus sylvestris, now D. fullonum; see letter from Francis Darwin, [28 May 1876]). He suggested that the filaments might enable the plant to absorb nitrogenous matter dissolved in the water in the cups formed by some of the leaves (see F. Darwin 1877b).


Comments on FD’s discovery – "if it so proves". It will be important to see whether the protoplasm oozes through the cell-walls [of Dipsacus] or whether it can be withdrawn.

Letter details

Letter no.
Charles Robert Darwin
Francis Darwin
Sent from
Source of text
DAR 271.3: 15
Physical description
ALS 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 10525,” accessed on 14 September 2023,

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