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Darwin Correspondence Project

From J. T. Moggridge   7 March 1874

Maison Gastaldy | Mentone

7 March | 1874

My dear Sir

I have to thank you for your most kind & much valued letter of Nov. 13, which contained some useful hints with reference to my seed experiments.—1 I should have written sooner, were it not that I feel bound to adhere to the rule I have made for myself to the effect that I must never trouble you with mere commonplace letters, & only permit myself the pleasure of addressing you when I have some distinct end in view.—

The immediate object which sanctions my letter of today is the extract which I enclose, giving an abstract of M. Ziegler’s observations on the sensitive movements of Drosera—. I hear that you are gathering up your materials on this subject, & it seemed to me just possible that this paper might have escaped you—.2

If not, you have only to destroy the paper & no harm is done—

I am now at work gathering up the facts which result from my experiments with acid vapours: & I hope that, though I have failed in a great measure to discover the secret of the ants, I shall be able to shew some curious & suggestive details bearing on germination generally, & inviting further research into the ‘microchemistry’ of these phenomena.—3

I have tried a great variety of experiments, & among others the one you suggested of touching the moistened, swollen seeds with a fine camelhair brush dipped in formic acid.—4 I did this with 6 peas, 6 cress & 6 millet, touching the seeds, as near the micropyle5 as possible, twice a day, the application being sufficient to leave a glistening & perceptible speck of acid on the seed; but the seeds germinated & grew as if nothing had happened!—

Pricking the moistened seeds with a needle dipped in formic acid had no apparent influence either; but soaking in dilute mixtures of formic acid & water proved very fatal.—

I have lately learned that the formic acid vapour, when 2 minims to 2 of distilled water are used, produces its injurious effects on the seeds within the covered tumblers much earlier than I had anticipated, & many hours before the seeds normally shew any external signs of germination.—

This was proved by resowing the seeds (6 peas, 6 cress, 6 millet) on clean sand & without acid after they had been exposed for different periods to the acid vapour— After exposure for 48 hours nothing germinated or shewed trace of germination in the resowing: after 29 hours exposure 2 peas germinated and grew in a mutilated way & 3 peas partially germinated but did not grow: after 24 hours 3 peas grew well but still no cress or millet: after 10 hours the peas & millet appeared uninjured & grew well but not one of the cress would germinate! Cress appears to be especially susceptible.—

Then I have made experiments with living harvesting ants, confining a very large number (about 100) in a corked test tube almost entirely filled with earth on the surface of which various seeds were placed— Here, though the confined air must have been saturated with any exhalations which are given off from the ants bodies, the seeds germinated well & without delay— Neither did seeds appear to be affected after having been confined for 12 hours in a small bottle with harvesting ants which were frequently made angry & excited by rolling the bottle from side to side.6

With the aid of an American gentleman, a friend of mine, Mr. J. B. Andrews,7 I have experimented with a variety of volatile substances, & it appears that all the following exercise a more or less injurious influence on seeds, almost all the seeds being either killed or permanently & profoundly hurt.—:—

Formic acid; Carbolic; Acetic; Muriatic; Chlorine solution; Iodine; Ammonia water; Oxyde of ethyl; Oil of cloves; Camphor—

The following do not appear to exercise any distinctly injurious influence:— Nitric acid; Sulphuric & Oxalic.—

Several openings for future experiment have suggested themselves to me during the course of my observations & I have taken note of these—

One point in particular has pressed itself on my attention, & this is the limitation of the period during which certain seeds will germinate, while others will germinate apparently on any day in any month in the year! It is not that the former have lost the power to germinate, but that they appear temporarily incapable of using it—

Hoping that you will forgive this rather formidable-looking letter, believe me yrs. most sincerely J. Traherne Moggridge.


Extract from Bull. Soc. Bot. Fr. Rev. Bib. tom xix (1872) p. 90.

Sur un fait physiologique observé sur les feuilles de Drosera; par M. Ziegler (Comptes Rendus, t. LXXIV, séance du 6 mai 1872, pp. 1227–1229.)”—.9

“M. Ziegler a reconnu que toutes les substances albuminoides animales qu’on a tenues pendant une minute entre les doigts acquièrent la propriété de faire contracter les cils des Drosera. Il a constaté aussi que les memes substances, quand elles n’ont pas été mises préalablement en contact avec un animal vivant, n’exercent aucune action de ce genre. Cette curieuse propriété peut être communiqué aux substances animales par le contact médial des doigts à travers du papier ciré fin. Elle se perd quant on humecte à plusieurs reprises ces substances avec de l’eau distillée, et qu’on les sèche chaque fois au bain marie.

D’un autre côté, des Drosera ont été placés, avec une petite motte de terre et suffisament d’eau, dans des capsules légères de platine, et ces capsules déposées chacune sur une poignée d’albumine du sang, qu’on avait eu soin de tenir pendant une demi-heure dans la main. Au bout de vingt-quatre heures, tous ces Drosera sont devenus complètement insensibles aux insectes, et aux corps organiques animaux, modifiés par le contact d’un être vivant. Les propriétés de ces plantes sont devenues inverses, et, chose merveilleuse, leurs cils se contractent alors sous l’influence de matières organiques qui avaient été d’abord mises en contact, pendant quelques minutes, avec des paquets de papier à double ou triple enveloppe, renfermant du sulfate de quinine, matières qui ne font point se contracter les cils des Drosera dans leur état normal.”

“Toutes les fois que, par une cause quelconque, un Drosera n’a plus les feuilles sensibles a l’impression des insectes, il suffit de placer la capsule de platine qui le contient sur un paquet de sulfate de quinine pour qu’il récupère peu a peu ses propriétés normales.”


CD’s letter, which has not been found, was a reply to Moggridge’s letter of 4 November 1873 (Correspondence vol. 21); Moggridge had discussed the effects of formic acid in suppressing the germination of seeds.
The abstract appeared in a separately paginated ‘Review bibliographique’ section of the Bulletin de la Société botanique de France (19 (1872); see n. 9, below). CD had begun writing on Drosera (sundew) in 1873; he began writing Insectivorous plants on 1 April 1874 (see ‘Journal’ (Appendix II)). He criticised Martin Ziegler’s views in Insectivorous plants, pp. 23 n., 249.
Moggridge had hoped that his experiments on the effects of formic and carbolic acid on seeds would explain why seeds collected by ants were rendered dormant (see Correspondence vol. 21, letter from J. T. Moggridge, 4 November 1873).
CD had made this suggestion in his letter to J. T. Moggridge, 27 August 1873 (Correspondence vol. 21).
The micropyle is the tiny hole in the protective coat of a seed through which water can be taken in to begin germination and through which the first root grows.
Moggridge published the results of these experiments, as well as those with formic acid suggested by CD, in the Supplement to Harvesting ants and trap-door spiders (Moggridge 1874, pp. 172–4). In Insectivorous plants, p. 128, CD referred to Moggridge’s experiments showing the injurious effects of the ‘weak acids of the acetic series’ on seeds.
James Bruyn Andrews lived in Mentone, France.
For a translation of the enclosure, see [Correspondence vol. 22] Appendix I.
Moggridge copied the text of the abstract that appeared in the Bulletin de la Société botanique de France 19 (1872): ‘Review bibliographique’, p. 90. Ziegler’s original note (Ziegler 1872) was published in Comptes rendus hebdomadaires des séances de l’Académie des sciences 74 (1872): 1227–9.


From J. T. Moggridge   7 March 1874


Extract from Bull. Soc. Bot. Fr. Rev. Bib. vol xix (1872) p. 90.

On a physiological fact observed on the leaves of Drosera; by M. Ziegler (Comptes Rendus, vol. LXXIV, meeting of 6 May 1872, pp. 1227–1229.)”2

“M. Ziegler recognised that all the albuminoid animal substances that he held for one minute between his fingers acquired the property of contracting the hairs of Drosera. He also noted that the same substances, when they had not been placed previously in contact with a living animal, did not cause any motion of this type. This curious property can be communicated to animal substances by the mediating contact of fingers through fine wax paper. This property disappears when one moistens these substances several times with distilled water, and dries them each time in a bain marie.

On the other hand, Drosera were placed, with a small lump of earth and enough water, in light platinum capsules, and these capsules each placed on a fistful of albumin from blood, which one had taken care to hold for half an hour in the hand. After twenty-four hours, all these Drosera became completely insensible to insects, and to organic animal bodies modified by contact with a living being. The properties of these plants became reversed, and, amazingly, their hairs contracted then under the influence of organic matter which had once been put into contact, for several minutes, with parcels wrapped in paper twice or three times, containing sulphate of quinine, substances that never cause Drosera to retract its hairs in its normal state.”

“Every time that, for whatever reason, Drosera no longer has leaves sensitive to the touch of insects, it is enough to place the capsule of platinum that contains it on a packet of sulphate of quinine for it to recover little by little its normal properties.”


For a transcription of this enclosure in its original French, see [Correspondence vol. 22] p. 135–6.
Moggridge copied the text of the abstract that appeared in the Bulletin de la Société botanique de France 19 (1872): ‘Review bibliographique’, p. 90. Ziegler’s original note (Ziegler 1872) was published in Comptes rendus hebdomadaires des séances de l’Académie des sciences 74 (1872): 1227–9.


Sends abstract of Martin Ziegler’s paper on sensitive movements in Drosera ["Sur un fait physiologique observé sur des feuilles de Drosera", C. R. Hebd. Acad. Sci. 74 (1872): 1227–9].

JTM’s experiments with formic acid and ants have failed to reveal the secret of the ants, but have taught him a great deal about germination.

Letter details

Letter no.
John Traherne Moggridge
Charles Robert Darwin
Sent from
Source of text
DAR 171: 224
Physical description
4pp, encl 2pp

Please cite as

Darwin Correspondence Project, “Letter no. 9339,” accessed on 18 July 2019,

Also published in The Correspondence of Charles Darwin, vol. 22