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Darwin Correspondence Project

From H. C. Watson   10 November 1856

Thames Ditton

Nov 10. 1856

My dear Sir

With great interest I have just been reading your experiments on the germination of seeds after lengthened immersion in salt water.—1

Botanists appear to have taken for granted or assumed too carelessly, that seeds must lose their vitality by immersion in salt water for a few weeks or days. It is an important matter to demonstrate a power of resistance to the supposed noxious influence, of one, two, or three months’ time.

Perhaps you in turn allow too much weight to the objections against migration over salt water, founded on the tendency of seeds to sink, & of plants to decay & sink.

Your experiments & observations are made in still water, of small depth, and small bulk.

1. Would not plants resist putrefaction much longer in agitated water, than in still water,—especially on the agitated surface of a sea, as compared with the still surface of a tub?

2. Take a glass of muddy water, from a turbid stream during flood. Speedily the fine particles of earth, &c. which make it muddy, will settle to the bottom. It would be contrary to fact, to assume from this, that streams, currents, tides, cannot carry muddy particles a long distance.

Before you can positively say, that the sinking of seeds in still water to a few inches, or few feet of depth, will prevent their crossing a sea, you must be convinced that they will sink so deep as to fall below motion in the sea. Not an easy matter to establish; altho’ the deeper they go, the less likely to get ashore again,—if not at the bottom.

Millions upon millions of seeds are carried to the sea yearly. Vast numbers of these must become entangled or resting among Algæ. Might not a sea weed occasionally float a land seed over a great extent of marine surface?— This seems to me as likely as timber floats, or whole plants from the land.

Sincerely yours | Hewett C. Watson

CD annotations

crossed pencil
crossed pencil
double scored pencil
Top of first page: ‘18’2 brown crayon
Bottom of last page: ‘Limosella’pencil, del pencil; ‘Hawks /Birds feet/ Earth in roots/’ pencil, del pencil

Footnotes

CD’s paper reporting the results of his and Miles Joseph Berkeley’s experiments ‘On the action of sea-water on the germination of seeds’ was read at the Linnean Society, 6 May 1856 (Collected papers 1: 264–73).
The number of CD’s portfolio of notes on the means of geographical dispersal of plants and animals.

Summary

Greatly interested in CD’s experiments with seeds in salt water [see "Action of sea-water on seeds", Collected papers 1: 264–73]. Believes CD exaggerates the force of the objection, against migration, that seeds tend to sink.

Letter details

Letter no.
DCP-LETT-1985
From
Hewett Cottrell Watson
To
Charles Robert Darwin
Sent from
Thames Ditton
Source of text
DAR 205.3: 296
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 1985,” accessed on 25 March 2019, http://www.darwinproject.ac.uk/DCP-LETT-1985

Also published in The Correspondence of Charles Darwin, vol. 6

letter