The Formation of Vegetable Mould Through the Action of Worms, with Observations on their Habits (sometimes shortened to Worms) is an 1881 book by Charles Darwin on earthworms. It was his last scientific book, and was published shortly before his death (see Darwin from Insectivorous Plants to Worms). Exploring earthworm behaviour and ecology, it continued the theme common throughout his work that gradual changes over long periods of time can lead to large and sometimes surprising consequences. It was the first significant work on soil bioturbation, although that term was not used by Darwin (it first appeared in the soil and geomorphic literature one hundred years later). Paper "On the Formation of Mould" After returning from the Beagle survey expedition in October 1836, Darwin was intensively occupied with further establishing his reputation as an innovative geologist, as well as finding suitable experts to describe his natural history collections and arranging for publication of their work as the multi-volume Zoology of the Voyage of H.M.S. Beagle. Near the outset of the voyage he had planned a book on geology, and during it extracts from his letters on geology had been privately published by his tutor John Stevens Henslow. Darwin now published papers on "proofs of recent elevation on the coast of Chili", "deposits containing extinct Mammalia" and "coral formations". He also rewrote his journal to incorporate observations from his notebooks as the book now called The Voyage of the Beagle, and began brain-storming in his notebooks about transmutation of species. Darwin's health suffered from the pressure of work, and on 20 September 1837 having been urged by his doctors "knock off all work" he visited his home in Shrewsbury then went on to stay with his relatives at Maer Hall, Staffordshire, home of his uncle Josiah Wedgwood. Uncle Jos pointed out an area of ground where lime and cinders spread years previously had vanished into the soil, forming layers under a top layer of loam. Jos suggested that this might have been the work of earthworms, but apparently thought that this would be of little interest to his nephew, who was working on continental scale geological problems. Actually, Charles did find it interesting and throughout his life he sustained an interest in this "unsung creature which, in its untold millions, transformed the land as the coral polyps did the tropical sea". He returned to London on October 21, and prepared a