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
Footnotes
Bibliography
Collected papers: The collected papers of Charles Darwin. Edited by Paul H. Barrett. 2 vols. Chicago and London: University of Chicago Press. 1977.
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
- ALS 4pp †
Please cite as
Darwin Correspondence Project, “Letter no. 1985,” accessed on 23 April 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-1985.xml
Also published in The Correspondence of Charles Darwin, vol. 6