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Letter 4230

Darwin, C. R. to Gardeners' Chronicle

2 July [1863]

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    Asks M. J. Berkeley to identify the microscopical spherical bodies CD found in drops of yellowish rain-water that fell on his garden in a brief shower.

Transcription

A very slight shower, lasting hardly more than a minute, fell here this morning (July 2) about 10 o'clock. My wife gathering some flowers immediately afterwards noticed that the drops of water appeared yellowish, and that the white Roses were all spotted and stained. I did not hear of this circumstance till the evening; I then looked at several Roses and Syringas and found them much stained in spots. Between the petals of the double white Roses there were still drops of the dirty water: and this when put under the microscope showed numerous brown spherical bodies, 11000 of an inch in diameter, and covered with short, conical transparent spines. There were other smaller, smooth, colourless sacs about 47000 of an inch in diameter. I preserved a minute drop of the water beneath thin glass, cementing the edges, and next morning looked rather more carefully at it. I then observed that the water swarmed with elongated, moving atoms, only just visible with a quarter-inch object glass. Whether these inhabited the rain-drops, when they fell, I cannot of course say; but I suspect so, for the petals, now that they are nearly dry, seem stained with absolutely impalpable matter of the colour of rust of iron. This matter has chiefly collected, in the act of drying, on the edges of each spot. The Rev. M. J. Berkeley could tell us what the larger spherical bodies are which fell this day by myriads from the sky, carried up there, I presume, by some distant whirlwind.

    Footnotes Add

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    f1 4230.f1
    CD's letter was reproduced in the Gardeners' Chronicle with explanatory notes by Miles Joseph Berkeley, who had been a regular contributor to the journal since its commencement in 1844 (DNB). Berkeley thought that the `larger bodies' described by CD were the `pollen grains of some Thistle or Centaurea'. He also noted that the `ferruginous spots on the white petals of Philadelphus' forwarded by CD consisted of `siliceous particles', and `multitudes of irregular bodies so minute as to present the Brownian molecular motion'.
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