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Darwin Correspondence Project

From J. T. Moggridge   30 July 1873

2 Montague Villas | Richmond | (Surrey)

30 July | 1873

My dear Sir

I have good hopes that I may before long be able to communicate details of some value with reference to the influence exercised upon seeds by formic acid, & I cannot resist the pleasure of writing to tell you that the beginning promises well.1

The seeds (Fumaria officinalis, Spergula arvensis, Reading Onion,— Red Celery, Millet, Emperor Peas, Euphorbia helioscopia, Amaranthus (Cock’s-Comb), Brocoli, Red Beet, Orange Carrot & Cress— six seeds of each kind except Spergula arvensis of which there were 10.)2 were placed on damp sand in tumblers as you recommended, with a small gallipot3 cover in the centre— Eleven tumblers were employed, ten containing acid or acid & water in the gallipot cover, & one, the control experiment, no acid— The experiments commenced at 7.0 p.m. on Monday last (July 28th.), & last night, after the lapse of little more than 24 hours, the cress seeds in the control tumbler (no acid) had begun to germinate, those in the other tumblers remaining intact.

At 2.0. p.m. today the same holds good, only the cress seeds have pushed out long radicles & young cotyledons & a pea & brocoli seed have sprouted—

Thus far the formic acid has certainly operated for the prevention of germination, & I begin to fear lest 5 minims, the smallest quantity employed, whether pure or mixed with water, may not prove to be too large a quantity.

Then I have also commenced some experiments on the effects of formic acid on mildew, being greatly struck with what you told me of the dead seeds, killed by formic acid vapour, not having contracted mildew. Five days ago I placed a small gallipot containing wet dough inside a covered tumbler; & in a second tumbler a similar gallipot full of dough but with a gallipot cover, containing 5 minims (7 drops) of pure formic acid, supported on a wire tripod, above it—

The vapour from the seven drops of formic acid has sufficed to keep the paste entirely free from mildew, while the dough in the other tumbler is now covered with a dense coat of blue & white mildew.

The paste in the formic-acid-tumbler has become very watery & of a yellowish salmon colour, but has been almost entirely free from bad smell, while that in the other tumbler became most offensive two days after the commencement of the expt.—

The sense of sight & the sense of smell distinctly proclaim the difference between the unprotected dough & that protected by formic acid vapour, & declare most distinctly that it has exercised a most powerful influence over the mode of decomposition & the resultant organisms in the dough—

I hope to repeat this experiment, & also those on seeds with carbolic in place of formic acid, as I have a wild hypothesis connecting the phenomena of germination in seeds with the formation of mildew.—

Believe me | yrs. most truly | J. Traherne Moggridge.


See letters from J. T. Moggridge, 22 July 1873 and 24 July 1873. CD had suggested that Moggridge ascertain whether formic acid prevented seed germination. The letter containing CD’s suggestions has not been found. Moggridge published the experiments in Moggridge 1874, pp. 172–4.
Fumaria officinalis is common fumitory; Spergula arvensis is corn spurrey; Euphorbia helioscopia is sun spurge. Cockscomb is now Celosia cristata (family Amaranthaceae).
Gallipot: a small glazed pot (Chambers).


Chambers: The Chambers dictionary. Edinburgh: Chambers Harrap Publishers. 1998.

Moggridge, John Traherne. 1874. Supplement to Harvesting ants and trap-door spiders: with specific descriptions of the spiders by the Rev. O. Pickard-Cambridge. London: L. Reeve & Co.


His preliminary results with formic acid show that it inhibits germination of several kinds of seed. It also inhibits growing of mildew, which he speculates may facilitate germination.

Letter details

Letter no.
John Traherne Moggridge
Charles Robert Darwin
Sent from
Source of text
DAR 171: 221
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 8990,” accessed on 23 January 2021,

Also published in The Correspondence of Charles Darwin, vol. 21