Gilbert White devotes one of his letters to earthworms. “Worms,” he says “ seem to be the great promoters of vegetation, which would “ proceed but lamely without them, by boring, perforating, and loosen-“ing the soil, and rendering it pervious to rains and the fibres of plants, “by drawing straws and stalks of leaves and twigs into it; and, most of “ all, by throwing up such infinite numbers of lumps of earth called “ worm-casts, which, being their excrement, is a fine manure for grain “and grass… the earth without worms would soon become cold, hard-“ bound, and void of fermentation, and consequently sterile.” Sixty years later, in 1837, Darwin published a paper, in which he showed the important part played by worms in the formation of vegetable mould. Further observations were recorded by Hensen in 1877. Agricultural chemists did not, however, generally make use of any of this work, and it was not till 1881 that the publication of Darwin's Earthworms and Vegetable Mould directed so much attention to the subject that the action of earthworms could no longer be disregarded. Several investigations have since been made into the part played by earthworms in promoting fertility, perhaps the best known being those recorded in Wollny's Zersetzung der organischen Stoffe.