LETTER 577. TO C. LYELL. [September, 1843.

An interesting fact has lately, as it were, passed through my hands. A Mr. Kemp (almost a working man), who has written on "parallel roads," and has corresponded with me (577/1. In a letter to Henslow, Darwin wrote: "If he [Mr. Kemp] had not shown himself a most careful and ingenious observer, I should have thought nothing of the case."), sent me in the spring some seeds, with an account of the spot where they were found, namely, in a layer at the bottom of a deep sand pit, near Melrose, above the level of the river, and which sand pit he thinks must have been accumulated in a lake, when the whole features of the valleys were different, ages ago; since which whole barriers of rock, it appears, must have been worn down. These seeds germinated freely, and I sent some to the Horticultural Society, and Lindley writes to me that they turn out to be a common Rumex and a species of Atriplex, which neither he nor Henslow (as I have since heard) have ever seen, and certainly not a British plant! Does this not look like a vivification of a fossil seed? It is not surprising, I think, that seeds should last ten or twenty thousand [years], as they have lasted two or three [thousand years] in the Druidical mounds, and have germinated.

When not building, I have been working at my volume on the volcanic islands which we visited; it is almost ready for press...I hope you will read my volume, for, if you don't, I cannot think of anyone else who will! We have at last got our house and place tolerably comfortable, and I am well satisfied with our anchorage for life. What an autumn we have had: completely Chilian; here we have had not a drop of rain or a cloudy day for a month. I am positively tired of the fine weather, and long for the sight of mud almost as much as I did when in Peru.

(577/2. The vitality of seeds was a subject in which Darwin continued to take an interest. In July, 1855 ("Life and Letters," II., page 65), he wrote to Hooker: "A man told me the other day of, as I thought, a splendid instance--and splendid it was, for according to his evidence the seed came up alive out of the lower part of the London Clay! I disgusted him by telling him that palms ought to have come up."

In the "Gardeners' Chronicle," 1855, page 758, appeared a notice (half a column in length) by Darwin on the "Vitality of Seeds." The facts related refer to the "Sand-walk" at Down; the wood was planted in 1846 on a piece of pasture land laid down as grass in 1840. In 1855, on the soil being dug in several places, Charlock (Brassica sinapistrum) sprang up freely. The subject continued to interest him, and we find a note dated July 2nd, 1874, in which Darwin recorded that forty-six plants of Charlock sprang up in that year over a space (14 x 7 feet) which had been dug to a considerable depth. In the course of the article in the "Gardeners' Chronicle," Darwin remarks: "The power in seeds of retaining their vitality when buried in damp soil may well be an element in preserving the species, and therefore seeds may be specially endowed with this capacity; whereas the power of retaining vitality in a dry artificial condition must be an indirect, and in one sense accidental, quality in seeds of little or no use to the species."

The point of view expressed in the letter to Lyell above given is of interest in connection with the research of Horace Brown and F. Escombe (577/3. "Proc. Roy. Soc." Volume LXII., page 160.) on the remarkable power possessed by dry seeds of resistance to the temperature of liquid air. The point of the experiment is that life continues at a temperature "below that at which ordinary chemical reactions take place." A still more striking demonstration of the fact has been made by Thiselton-Dyer and Dewar who employed liquid hydrogen as a refrigerant. (577/4. Read before the British Association (Dover), 1899, and published in the "Comptes rendus," 1899, and in the "Proc. R. Soc." LXV., page 361, 1899.) The connection between these facts and the dormancy of buried seeds is only indirect; but inasmuch as the experiment proves the possibility of life surviving a period in which no ordinary chemical change occurs, it is clear that they help one to believe in greatly prolonged dormancy in conditions which tend to check metabolism. For a discussion of the bearing of their results on the life-problem, and for the literature of the subject, reference should be made to the paper by Brown and Escombe. See also C. de Candolle "On Latent Life in Seeds," "Brit. Assoc. Report," 1896, page 1023 and F. Escombe, "Science Progress," Volume I., N.S., page 585, 1897.)