The Formation of Vegetable Mould Through the Action of Worms
Author | Charles Darwin |
---|---|
Country | England |
Language | English |
Subject | Earthworms |
Publisher | John Murray |
Publication date | October 1881 |
Pages | 326 (1st edition) |
Preceded by | The Power of Movement in Plants |
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.[1] 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.[2]
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.[3] 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 paper on worms forming mould.
The paper appeared in the Proceedings of the Geological Society of London in 1838,[5] and was published with a woodcut illustration in the Transactions of the Geological Society in 1840.[7]
Renewed work on earthworms
From his brain-storming about transmutation towards the end of 1838, Darwin conceived of his theory of natural selection "by which to work", as his "prime hobby". His main work on the Beagle collections continued, and in 1842 he published the first of three volumes on geology, The Structure and Distribution of Coral Reefs. He then allowed himself to write out the first "pencil sketch" of his theory. Subsequently, in September 1842, the family moved to rural Down House where he had space for experimental plant and animal breeding, and surroundings to observe nature.[2] In December of that year he had a quantity of broken chalk spread over a part of a long established pasture field near the house, "for the sake of observing at some future period to what depth it would become buried."[8]
In 1872 he was having disagreements with
By 1876, with his
He was occupied by worms at Downe in 1880, his work coming first. He had help from the family, even receiving soil samples from Abinger's Roman ruins.[12] He told Vladimir Kovalevsky (his Russian translator) of slow progress with his new book.[13]
Darwin calculated that there were 53,767 earthworms recycling away per acre. He carried out experiments indoors, where they worked the earth inside pots in a worm-littered room. He experimented with stimuli at night: strong light would send them into their burrows ("like a rabbit" said Darwin's grandson Bernard), but heat and sound had no effect. Their food preferences were also tested, raw carrots being their favourite.[14]
Darwin was fascinated by their behaviour, from enjoying "the pleasure of eating" (based on their eagerness for certain foods) to their sexual passions, "strong enough to overcome... their dread of light", even to their social feelings ("crawling over each other's bodies").[15] Their foraging was especially intriguing: they dragged leaves into their burrows, pulling them in the most efficient way, by their pointed end. On these semi-intelligent creatures Darwin wrote that they obtained a "notion, however rude, of the shape of an object", perhaps by feeling it out. Worms, "five or six feet" below the ground ploughed farmers fields. Darwin felt we "ought to be grateful" to these little recyclers, which he compared to "a man... born blind and deaf". He was wondering how long it would be until he would be consumed by worms himself[citation needed]. It would surely be his last major work; he told German translator Victor Carus "I have little strength & feel very old".[14]
By 1881 he was unable to summon the strength for revisions and handed Worms on to
At a dinner with
Summary
Worms are found in many places, from the forest floor to mountains, and in many locations around the world. Though they are considered terrestrial animals, they are really semi-aquatic, like other
Thin leaves are seized with the mouth, while thick ones are dragged by creating a vacuum. Leaves and stones are used to plug up the burrow. This may deter predators, keep out water and/or keep out chilled air (the latter is Darwin's preferred function). Leaves are dragged in mostly by the tips, which is the easiest way of doing it, but when the base is narrower the worms change behaviour. They drag
The amount of earth brought to the surface by worms can be estimated by the rate at which objects on the surface are buried and by weighing the earth brought up in a given time. Information from farmers on marl, cinders etc. sinking into the ground allowed Darwin to make calculations. He conducted a 29-year experiment on chalk at a field near his house. Objects of all sorts "work themselves downards" as farmers say. Large stones sink because worms fill up any hollows with castings, then eject them beyond the perimeter and the ground around them starts to rise. He visited Stonehenge and found some outer stones partly buried, the turf sloping up to meet them (see figure 7). Darwin weighed castings and had friends do so in other countries. He also weighed castings per unit area per year, then worked out how thick a layer castings would make, compared with rates of sinking. Additionally, he worked out casting weight per worm per year.
Worms have preserved many ancient objects under the ground. Darwin describes an ancient Roman villa in Abinger, Surrey. Worms have penetrated the concrete walls and even mortar. Similar subsidence occurred at Beaulieu Abbey, Hampshire, with worms penetrating gaps between the tiles. His sons Francis and Horace visited Chedworth Roman Villa in Gloucestershire, while William reported on Brading Roman Villa, Isle of Wight. Darwin goes into some detail on the well preserved ruins of Silchester Roman Town, Hampshire, with the help of the Rev. J. G. Joyce. Finally he discusses the case of the Viroconium Roman town ruins at Wroxeter, Shropshire, with the help of Dr. H. Johnson, who made observations including depth of vegetable mould. He concludes that both worms and other causes, such as dust deposition and washing down of soil, have buried such ruins.
Rain causes castings to move down an incline; Darwin worked out the weight moving a certain distance in a given time. Some also roll down, and collect in drains etc., or get blown. There is a greater effect on casting movement in the tropics, because of increased rain. The finest earth is washed away. Ledges on hillsides, formerly believed to be caused by grazing mammals, are partly due to casting accumulations. High winds, especially gales, are almost as effective as the slope/rain in moving castings. Crowns and furrows of formerly ploughed lands slowly vanish when under pasture, due to worms, but more slowly when there is no incline. Fine earth is washed down from slopes, making a shallow layer. Dissolving of chalk supplies new earth.
Darwin writes in the conclusion that worms "have played a more important part in the history of the world than most persons would at first suppose."[19] They are important for many reasons, including their role in decomposition of rocks, gradual denudation of the land, preservation of archaeological remains, and improving soil conditions for plant growth. Despite their rudimentary sense organs, they show complex, flexible behaviour.
Reception
Worms became available in October 1881 and sold thousands of copies in its first few weeks, despite Darwin's comment to Carus that it was "a small book of little moment".[15] Darwin received a "laughable" number of letters containing questions, observations and ideas, even "idiotic" ones. A week's holiday with Emma in Cambridge was to follow. Darwin died the next year on 19 April 1882.[20]
See also
- Uniformitarianism
- Ichnology
- Burrow
- Trace fossil
References
Citations
- ^ "Review of The Formation of Vegetable Mould, through the action of Worms, with observations on their Habits". The Quarterly Review. 153: 179–202. January 1882.
- ^ a b van Wyhe 2009
- ^ a b Desmond & Moore 1991, pp. 233–234
- ^ Darwin 2006, pp. 12 verso–13 recto
- ^ a b Darwin 1838
- ^ Darwin Correspondence Project – Letter 404 – Buckland, William to Geological Society of London, 9 Mar 1838, retrieved 23 December 2008
- ^ Darwin 1840
- ^ Darwin 1881, p. 139
- ^ Desmond & Moore 1991, p. 592
- ^ Desmond & Moore 1991, p. 622
- ^ Desmond & Moore 1991, p. 628
- ^ Desmond & Moore 1991, p. 643
- ^ Desmond & Moore 1991, p. 648
- ^ a b Desmond & Moore 1991, p. 649
- ^ a b Desmond & Moore 1991, p. 650
- ^ Desmond & Moore 1991, p. 652
- ^ Desmond & Moore 1991, p. 654
- ^ Desmond & Moore 1991, p. 657
- ^ Darwin 1881, p. 305.
- ^ Desmond & Moore 1991, p. 658
Sources
- ISBN 978-0-7181-3430-3
- Darwin, C. R. (1838), "On the formation of mould. (Read 1 November 1837)", Proceedings of the Geological Society of London, vol. 2, pp. 574–576, retrieved 12 February 2009
- Darwin, C. R. (1840), "On the formation of mould. (Read 1 November 1837)", Transactions of the Geological Society, 2, vol. 5, no. 2, London, pp. 505–509, retrieved 12 February 2009
- Darwin, C. R. (1881), The formation of vegetable mould, through the action of worms, with observations on their habits, London: John Murray, retrieved 12 February 2009
- Darwin, Charles (2006), "Journal", in bvan Wyhe, John (ed.), [Darwin's personal 'Journal' (1809–1881)], Darwin Online, CUL-DAR158.1–76, retrieved 12 February 2009
- van Wyhe, John (2009), Charles Darwin: gentleman naturalist: A biographical sketch, Darwin Online, retrieved 12 February 2009
Further reading
- "Down among the Worms", chapter 42 in Desmond, Adrian; ISBN 978-0-7181-3430-3
- Romanes, George J (1881). "The Formation of Vegetable Mould through the Action of Worms, with Observations on their Habits". Nature. 24 (624): 553–6. S2CID 42141622.
External links
- The Formation of Vegetable Mould through the Action of Worms with Observations on their Habits LibriVox
- The Formation of Vegetable Mould through the Action of Worms with Observations on their Habits at One More Library
- The formation of vegetable mould through the action of worms, with observations on their habits. London: John Murray. 1881; 326 pages
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