"Around the house no trace appeared to remain of the former labours of the owner. Darwin used simple means. He was not one who would have demanded to have palaces built in order to accommodate laboratories. I looked for the greenhouse in which such beautiful experiments on hybrid plants had been made. It contained only a vine. One thing struck me, although it is not rare in England, where animals are loved. A heifer and a colt were feeding close to us with the tranquillity which tells of good masters, and I heard the joyful barking of dogs. 'Truly,' I said to myself, 'the history of the variations of animals was written here, and observations must be going on, for Darwin is never idle.' I did not suspect that I was walking above the dwellings of those lowly beings called earthworms, the subject of his last work, in which Darwin showed once more how little causes in the long run produce great effects. He had been studying them for thirty years, but I did not know it. "Returning to the house, Darwin showed me his library, a large room on the ground floor, very convenient for a studious man; many books on the shelves; windows on two sides; a writing-table and another for apparatus for his experiments. Those on the movements of stems and roots were still in progress. The hours passed like minutes. I had to leave. Precious memories of that visit remain." Yet once more, in 1881, the famous publishing house of Murray issued a new work--his last--by the great illuminator of Nature. Its subject was one which no one save those who knew him could have expected. It dealt with "The Formation of Vegetable Mould, through the Action of Worms, with Observations on their Habits," and in it the lowly earthworm was at last raised to its true rank as the genuine preparer and possessor of the soil. Both Gilbert White and Edward Jenner had been impressed with the work earthworms do in nature, but no one had written extensively on the subject till Darwin himself, in 1837, read a short paper on the "Formation of Mould" before the Geological Society of London (published in the fifth volume of the Society's Transactions), showing that small fragments of burnt marl, cinders, &c., which had been thickly strewed over the surface of several meadows, were found after a few years lying at the depth of some inches beneath the turf. It was suggested to him by his relative Mr. Wedgwood, of Maer Hall, in Staffordshire, that this was due to the quantity of fine earth continually brought up to the surface by worms in the form of castings. Observation and experiment were to settle the question in the usual Darwinian manner, and many a portion of soil was watched. One experiment lasted nearly thirty years, for a quantity of broken chalk and sifted coal cinders was spread on December 20, 1842, over distinct parts of a field near Down House, which had