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The Formation of Vegetable Mould through the action of worms withobservations of their habitsby Charles DarwinINTRODUCTION.The share which worms have taken in the formation of the layer ofvegetable mould, which covers the whole surface of the land inevery moderately humid country, is the subject of the presentvolume. This mould is generally of a blackish colour and a fewinches in thickness. In different districts it differs but littlein appearance, although it may rest on various subsoils. Theun