To Gardeners’ Chronicle 21 November 
As you have published notices by Mr. Berkeley and myself on the length of time seeds can withstand immersion in sea-water, you may perhaps like to hear, without minute details, the final results of my experiments. The seed of Capsicum, after 137 days’ immersion, came up well, for 30 out of 56 planted germinated, and I think more would have grown with time. Of Celery only 6 out of some hundreds came up after the same period of immersion. One single Canary seed grew after 120 days, and some Oats half germinated after 120; both Oats and Canary seed came up pretty well after only 100 days. Spinach germinated well after 120 days. Seed of Onions, Vegetable Marrow, Beet, Orache and Potatoes, and one seed of Ageratum mexicanum grew after 100 days. A few, and but very few, seed of Lettuce, Carrot, Cress, and Radish came up after 85 days’ immersion. It is remarkable how differently varieties of the same species have withstood the ill effects of the salt water; thus, seed of the “Mammoth White Broccoli” came up excellently after 11 days, but was killed by 22 days’ immersion; “early Cauliflower” survived this period, but was killed by 36 days; “Cattell’s Cabbage” survived the 36 days, but was killed by 50 days; and now I have seed of the wild Cabbage from Tenby growing so vigorously after 50 days, that I am sure that it will survive a considerably longer period. But the seed of the wild Cabbage was fresh, and some facts show me that quite fresh seed withstands the salt water better than old, though very good seed. With respect to an important point in my former communication of May 26th,1 permit me to cry peccavi; having often heard of plants and bushes having been seen floating some little distance from land, I assumed—and in doing this I committed a scientific sin—that plants with ripe seed or fruit would float at least for some weeks. I always meant to try this, and I have now done so with sorrowful result; for having put in salt-water between 30 and 40 herbaceous plants and branches with ripe seed of various orders, I have found that all (with the exception of the fruit of evergreens2 ) sink within a month, and most of them within 14 days. So that, as far as I can see, my experiments are of little or no use (excepting perhaps as negative evidence) in regard to the distribution of plants by the drifting of their seeds across the sea. Can any of your readers explain the following sentence by Linnæus, pointed out to me by Dr. Hooker, “Fundus maris semina non destruit”? Why does Linnæus say that the bottom of the sea does not destroy seeds? The seeds which are often washed by the Gulf Stream to the shores of Norway, with which Linnæus was well acquainted, float, as I have lately tried. Did he imagine that seeds were drifted along the bottom of the ocean? This does not seem probable, from the currents of the sea, at least many of them, being superficial. Charles Darwin, Down, Nov. 21. —P.S. In my communication on Charlock seed lately printed by you,3 there is a misprint of “6 plants” for “6 plots of ground,” which makes nonsense of the sentence.
Sends final results of his experiments on the vitality of various kinds of seeds immersed in sea-water. Corrects a false assumption he made in an earlier letter  that plants with ripe seeds would float for some weeks. Now finds that they sink within a month. Since all the seeds he tried sank in sea-water, his experiments are of little or no use "in regard to the distribution of plants by drifting of their seeds across the sea".
Please cite as
Darwin Correspondence Project, “Letter no. 1783,” accessed on 30 July 2016, http://www.darwinproject.ac.uk/DCP-LETT-1783