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==Background== |
==Background== |
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[[File:Herminium monorchis (plant).jpg|thumb|left|alt=spires of small flowers among grass|[[Musk Orchid|Musk orchids]] in grassland]] |
[[File:Herminium monorchis (plant).jpg|thumb|left|alt=spires of small flowers among grass|[[Musk Orchid|Musk orchids]] in grassland]] |
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[[Charles Darwin]] grew up with an interest in [[natural history]], and as a student at the [[University of Cambridge]] he became a pupil and close friend of [[botany]] professor [[John Stevens Henslow]]. The year that he graduated, Darwin was given a place as a gentleman naturalist and [[geology|geologist]] on the [[Second voyage of HMS Beagle|Beagle voyage]], a voyage that lasted five years. By the time of his return in October 1836, he doubted the doctrine that species were fixed and unchanging. |
[[Charles Darwin]] grew up with an interest in [[natural history]], and as a student at the [[University of Cambridge]] he became a pupil and close friend of [[botany]] professor [[John Stevens Henslow]]. The year that he graduated, Darwin was given a place as a gentleman naturalist and [[geology|geologist]] on the [[Second voyage of HMS Beagle|Beagle voyage]], a voyage that lasted five years. By the time of his return in October 1836, he doubted the doctrine that species were fixed and unchanging. Expert information about his specimens inspired the [[inception of Darwin's theory|inception of his theory]] of [[natural selection]] in 1838. Darwin took on the editing and publication of expert reports, collected in the ''[[Zoology of the Voyage of H.M.S. Beagle]]'', at the same time as writing books on geology, beginning with ''[[The Structure and Distribution of Coral Reefs]]''. His "species work" was his "prime hobby" in the background to this writing, and became an extensive research programme during the twenty years before he [[publication of Darwin's theory|published his theory]].<ref>{{harvnb|van Wyhe|2008|pp=14–16, 31, 44–45}}</ref> |
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===Insect fertilisation of plants=== |
===Insect fertilisation of plants=== |
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From the outset, Darwin's speculations on the origin of species convinced him that [[Allogamy|cross-fertilisation]] played an important part in keeping specific forms consistent. He rejected the doctrine that the characteristics of a species were invariable, and was aware from [[animal husbandry]] that [[inbreeding]] could lead to changes, often deleterious. He thought that natural [[Heterosis|outbreeding]] through cross-fertilisation would keep wild species homogenous and vigorous. Cross-fertilisation would give an evolutionary advantage by spreading favourable changes throughout a reproductive community. His ideas were contrary to the common supposition that plants were usually self-fertilising, so every summer he investigated the contribution of [[Entomophily|insect pollination]] to the [[allogamy|cross-pollination]] of [[flower]]s.<ref name=bio>{{harvnb|Darwin|1958|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1497&pageseq=133 127–128]}}</ref><ref name=vogel56>{{harvnb|Vogel|1996|pp=56–57}}</ref> |
From the outset, Darwin's speculations on the origin of species convinced him that [[Allogamy|cross-fertilisation]] played an important part in keeping specific forms consistent. He rejected the doctrine that the characteristics of a species were invariable, and was aware from [[animal husbandry]] that [[inbreeding]] could lead to changes, often deleterious. He thought that natural [[Heterosis|outbreeding]] through cross-fertilisation would keep wild species homogenous and vigorous. Cross-fertilisation would give an evolutionary advantage by spreading favourable changes throughout a reproductive community. His ideas were contrary to the common supposition that plants were usually self-fertilising, so every summer he investigated the contribution of [[Entomophily|insect pollination]] to the [[allogamy|cross-pollination]] of [[flower]]s.<ref name=bio>{{harvnb|Darwin|1958|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1497&pageseq=133 127–128]}}</ref><ref name=vogel56>{{harvnb|Vogel|1996|pp=56–57}}</ref> |
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In the summer of 1841, Charles and [[Emma Darwin]] moved from the turmoil of [[London]] to the countryside |
In the summer of 1841, Charles and [[Emma Darwin]] moved from the turmoil of [[London]] to the countryside village of [[Downe]] and their family home, [[Down House]]. He wrote, "The flowers are here very beautiful".<ref>{{harvnb|Darwin|Seward|1903|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1548.1&pageseq=68 31–33]}}</ref> At about the same time, Darwin followed the recommendation of his friend, the leading botanist [[Robert Brown (botanist)|Robert Brown]], and read ''[[Das entdeckte Geheimnis der Natur im Bau und in der Befruchtung der Blumen]]'' (''The Secret of Nature in the Form and Fertilisation of Flowers Discovered''<ref>{{harvnb|Vogel|1996|p=44}}</ref>).<ref name=bio/> This little known book, published in 1793 by [[Christian Konrad Sprengel]] but never translated into English, introduced the idea that flowers were created by God to fulfill a [[teleology|teleological purpose]]: insects would act as "living brushes" to cross-fertilise plants in a [[symbiosis|symbiotic]] relationship. This functional view was rejected and mostly forgotten, as it contradicted beliefs that flowers had been created for beauty and were generally self-fertilising. For Darwin, evolution gave new meaning to Sprengel's research into mechanisms for cross-fertilisation. He welcomed its support for his supposition that flowering plants tended to escape disadvantages caused to their offspring by self-fertilisation,<ref name=v44>{{harvnb|Vogel|1996|pp=44–57}}</ref> and by 1845 he had verified many of Sprengel's observations.<ref name=Letter889>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-889.html |title=Darwin Correspondence Project - Letter 889 — Darwin, C. R. to Hooker, J. D., (11–12 July 1845) |accessdate=2009-07-20}}</ref> |
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A favourite walk took the Darwin family to a beautiful spot above the quiet [[Cudham]] valley, teeming with orchids including ''[[Cephalanthera]]'', ''[[Neottia nidus-avis|Neottia]]'', [[Fly Orchid|fly orchids]] and [[Musk Orchid|musk orchids]]. They called this place "Orchis Bank", and the whole family became involved in Darwin's researches.<ref>{{harvnb|Darwin|1887|p=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1452.1&pageseq=134 116]}}</ref> Darwin watched orchids every summer, but in twenty years, only on two occasions (when he noticed butterflies "sucking [[Pyramidal orchid|''O. pyramidalis'']] and ''[[Gymnadenia]]''") did he see insects visiting flowers.<ref name=orchids58>{{harvnb|Darwin|1862|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F800&pageseq=49 34–39]}}</ref> |
A favourite walk took the Darwin family to a beautiful spot above the quiet [[Cudham]] valley, teeming with orchids including ''[[Cephalanthera]]'', ''[[Neottia nidus-avis|Neottia]]'', [[Fly Orchid|fly orchids]] and [[Musk Orchid|musk orchids]]. They called this place "Orchis Bank", and the whole family became involved in Darwin's researches.<ref>{{harvnb|Darwin|1887|p=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1452.1&pageseq=134 116]}}</ref> Darwin watched orchids every summer, but in twenty years, only on two occasions (when he noticed butterflies "sucking [[Pyramidal orchid|''O. pyramidalis'']] and ''[[Gymnadenia]]''") did he see insects visiting flowers.<ref name=orchids58>{{harvnb|Darwin|1862|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F800&pageseq=49 34–39]}}</ref> |
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In 1854 Darwin began full time work on the origin of species.<ref name=vw45>{{harvnb|van Wyhe|2008|pp=45–47}}</ref> He examined orchids and counted how often one or both [[Pollinium|pollinia]] had been removed from their flowers which indicated that they had been visited by insects.<ref>{{harvnb|Darwin|1862|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F800&pageseq=72 57–60]}}</ref> He experimented on insect pollination to investigate if field crops such as [[Fabaceae]] yielded more vigourous offspring when they were cross-fertilised, and published letters about his rather inconclusive results in ''The Gardeners' Chronicle'' in 1857 and 1858. He then applied Sprengel's methods to empirical research on orchids.<ref name=vogel56/><ref>{{harvnb|Darwin|1857|p=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1697&pageseq=1 725]}},<br>{{harvnb|Darwin|1858|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1701&pageseq=1 828–829]}}</ref> Despite delays caused by [[Charles Darwin's illness|recurring illness]], he made good progress on writing his planned "Big Book" on [[evolution]], but |
In 1854 Darwin began full time work on the origin of species.<ref name=vw45>{{harvnb|van Wyhe|2008|pp=45–47}}</ref> He examined orchids and counted how often one or both [[Pollinium|pollinia]] had been removed from their flowers which indicated that they had been visited by insects.<ref>{{harvnb|Darwin|1862|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F800&pageseq=72 57–60]}}</ref> He experimented on insect pollination to investigate if field crops such as [[Fabaceae]] yielded more vigourous offspring when they were cross-fertilised, and published letters about his rather inconclusive results in ''The Gardeners' Chronicle'' in 1857 and 1858. He then applied Sprengel's methods to empirical research on orchids.<ref name=vogel56/><ref>{{harvnb|Darwin|1857|p=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1697&pageseq=1 725]}},<br>{{harvnb|Darwin|1858|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1701&pageseq=1 828–829]}}</ref> Despite delays caused by [[Charles Darwin's illness|recurring illness]], he made good progress on writing his planned "Big Book" on [[evolution]], but [[Alfred Russel Wallace]]'s letter prompted joint publication of both of their theories of [[natural selection]] in 1858, and Darwin quickly wrote ''[[On the Origin of Species]]'' as an abstract of his theory, published on 22 November 1859.<ref name=vw45/> In this book, he gave credence to Sprengel's ideas on the advantages of "intercrossing".<ref>{{harvnb|Darwin|1859|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F373&pageseq=113 98–99], [http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F373&pageseq=163 145–146]}}</ref> and noted, "Many of our orchidaceous plants absolutely require the visits of moths to remove their pollen-masses and thus to fertilise them".<ref>{{harvnb|Darwin|1859|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F373&pageseq=88 73–74]}}</ref> He then introduced for the first time his new concept of the process of [[coevolution]], describing the co–adaption of [[bumblebee]]s and [[Trifolium pratense|red clover]] and speculating "how a flower and a bee might slowly become, either simultaneously or one after the other, modified and adapted in the most perfect manner to each other, by the continued preservation of individuals presenting mutual and slightly favourable deviations of structure." This was a theme he developed in his orchid book.<ref name=t24>{{harvnb|Thompson|1994|pp=24–25}}</ref><ref>{{harvnb|Darwin|1859|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F373&pageseq=109 94–95]}}</ref> |
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==Research, writing and publication== |
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==Botany as recreation== |
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[[File:Ophrys apifera (flower).jpg|thumb|right|alt=a light purple flower, with a bulging lower petal coloured black and yellow|The [[Bee Orchid|bee orchid]] does not have [[nectar]], but its [[labellum]] imitating a female bee attracts male bees. Darwin found that in northern Europe, it is mostly self-fertilising.]] |
[[File:Ophrys apifera (flower).jpg|thumb|right|alt=a light purple flower, with a bulging lower petal coloured black and yellow|The [[Bee Orchid|bee orchid]] does not have [[nectar]], but its [[labellum]] imitating a female bee attracts male bees. Darwin found that in northern Europe, it is mostly self-fertilising.]] |
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After ''[[On the Origin of Species]]'' was published, Darwin became involved in producing revisions for new editions as well as working on ''[[Variation of Animals and Plants Under Domestication]]'', as the first part of his planned "Big Book".<ref>{{harvnb|Browne|2002|pp=100–102}}</ref><ref>{{harvnb|van Wyhe|2008|pp=52–53}}</ref> |
After ''[[On the Origin of Species]]'' was published, Darwin became involved in producing revisions for new editions as well as working on ''[[Variation of Animals and Plants Under Domestication]]'', as the first part of his planned "Big Book".<ref>{{harvnb|Browne|2002|pp=100–102}}</ref><ref>{{harvnb|van Wyhe|2008|pp=52–53}}</ref> |
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By the spring of 1860 he had become tired of the grind of writing, and needed something fresh and interesting to study. |
By the spring of 1860 he had become tired of the grind of writing, and needed something fresh and interesting to study. While out on a search for orchids he noticed a [[Drosera|sundew]], collected it and tried to feed it insects, beginning a long-term study of [[Carnivorous plant|insectivorous plants]]. He investigated other [[botany|botanical]] questions raised by his ideas of [[natural selection]], including the advantages of [[sexual dimorphism]] in [[primula]]s, and the adaptive mechanisms that ensure cross-pollination in orchids.<ref>{{harvnb|Browne|2002|pp=146–148}}</ref><ref name=volume8>{{citation |url=http://www.darwinproject.ac.uk/content/view/26/38/ |title=Darwin Correspondence Project - The correspondence of Charles Darwin, volume 8: 1860 |accessdate=2009-02-03}}</ref> As an enthusiastic practical scientist, such investigations gave him a strong sense of personal enjoyment. He relished pitting his wits against nature, and following lucky hunches. His theory was a way of looking at the world, enabling him to find creative solutions to problems that traditional approaches could not solve. He later wrote, "I am like a gambler, & love a wild experiment."<ref name=b166>{{harvnb|Browne|2002|pp=166–167}}</ref><ref name=Letter4061>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-4061.html |title=Darwin Correspondence Project - Letter 4061 — Darwin, C. R. to Hooker, J. D., 26 (Mar 1863) |accessdate=2009-06-25}}</ref> |
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Around the end of April 1860, Darwin discussed insect pollination with his friend [[Joseph Dalton Hooker]],<ref name=Letter2770>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2770.html |title=Darwin Correspondence Project - Letter 2770 — Darwin, C. R. to Hooker, J. D., 27 April (1860) |accessdate=2009-02-03}}</ref> and mentioned the [[Bee Orchid|bee orchid]].<ref name=Letter2776>{{citation |url= http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2776.html |title=Darwin Correspondence Project - Letter 2776 — Darwin, C. R. to Hooker, J. D., 30 Apr (1860) |accessdate=2009-02-03}}</ref> Darwin corresponded with Hooker's assistant [[Daniel Oliver]], the senior curator at [[Kew Gardens]], who became a follower of Darwin's ideas.<ref name=b166/> At the start of June, Darwin wrote to ''[[The Gardeners' Chronicle]]'' asking for readers' observations on how [[Ophrys|bee or fly orchids]] were fertilised. His letter described the mechanisms for insect fertilisation he had discovered in common British orchids, and reported his investigations and experiments that found that pollen masses were removed from ''[[Green-winged Orchid|Orchis morio]]'' and ''[[Orchis mascula]]'' plants in the open, but left in their pouches in adjacent plants under a glass [[bell jar]].<ref name=Letter2826>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2826.html |title=Darwin Correspondence Project - Letter 2826 — Darwin, C. R. to Gardeners' Chronicle, (4 or 5 June 1860) |accessdate=2009-02-03}}</ref> He wrote to American botanist [[Asa Gray]] that he had been "so struck with admiration at the contrivances, that I have sent notice to Gardeners Chronicle",<ref name=Letter2825>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2825.html#back-mark-2825.f7 |title=Darwin Correspondence Project - Letter 2825 — Darwin, C. R. to Gray, Asa, 8 June (1860) |accessdate=2009-02-04}}</ref> and made similar enquiries of other experts.<ref name=Letter2829>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2829.html |title=Darwin Correspondence Project - Letter 2829 — Darwin, C. R. to Stainton, H. T., 11 June (1860) |accessdate=2009-02-04}}</ref> |
Around the end of April 1860, Darwin discussed insect pollination with his friend [[Joseph Dalton Hooker]],<ref name=Letter2770>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2770.html |title=Darwin Correspondence Project - Letter 2770 — Darwin, C. R. to Hooker, J. D., 27 April (1860) |accessdate=2009-02-03}}</ref> and mentioned the [[Bee Orchid|bee orchid]].<ref name=Letter2776>{{citation |url= http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2776.html |title=Darwin Correspondence Project - Letter 2776 — Darwin, C. R. to Hooker, J. D., 30 Apr (1860) |accessdate=2009-02-03}}</ref> Darwin corresponded with Hooker's assistant [[Daniel Oliver]], the senior curator at [[Kew Gardens]], who became a follower of Darwin's ideas.<ref name=b166/> At the start of June, Darwin wrote to ''[[The Gardeners' Chronicle]]'' asking for readers' observations on how [[Ophrys|bee or fly orchids]] were fertilised. His letter described the mechanisms for insect fertilisation he had discovered in common British orchids, and reported his investigations and experiments that found that pollen masses were removed from ''[[Green-winged Orchid|Orchis morio]]'' and ''[[Orchis mascula]]'' plants in the open, but left in their pouches in adjacent plants under a glass [[bell jar]].<ref name=Letter2826>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2826.html |title=Darwin Correspondence Project - Letter 2826 — Darwin, C. R. to Gardeners' Chronicle, (4 or 5 June 1860) |accessdate=2009-02-03}}</ref> He wrote to American botanist [[Asa Gray]] that he had been "so struck with admiration at the contrivances, that I have sent notice to Gardeners Chronicle",<ref name=Letter2825>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2825.html#back-mark-2825.f7 |title=Darwin Correspondence Project - Letter 2825 — Darwin, C. R. to Gray, Asa, 8 June (1860) |accessdate=2009-02-04}}</ref> and made similar enquiries of other experts.<ref name=Letter2829>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2829.html |title=Darwin Correspondence Project - Letter 2829 — Darwin, C. R. to Stainton, H. T., 11 June (1860) |accessdate=2009-02-04}}</ref> |
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Darwin became engrossed in meticulous microscopic examination, tracing the complicated mechanisms of flowers that attracted insects by their nectar so that the insects transported pollen to cross-pollinate other plants, and on 19 July he told Hooker, "I am intensely interested on subject, just as at a game of chess."<ref name=volume8/><ref name=Letter2871>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2871.html |title=Darwin Correspondence Project - Letter 2871 — Darwin, C. R. to Hooker, J. D., 19 (July 1860) |accessdate=2009-02-03}}</ref> In September, he "dissected with the greatest interest" and wrote, "The contrivances for insect fertilisation in Orchids are multiform & truly wonderful & beautiful."<ref name=Letter2920>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2920.html |title=Darwin Correspondence Project - Letter 2920 — Darwin, C. R. to Gordon, George (b), 17 Sept (1860) |accessdate=2009-02-06}}</ref> By October, he had "a large mass of notes with many new facts", but set them aside "convinced that I ought to work on ''Variation'' & not amuse myself with interludes".<ref name=Letter2956>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2956.html |title=Darwin Correspondence Project - Letter 2956 — Darwin, C. R. to Oliver, Daniel, 20 Oct (1860) |accessdate=2009-02-06}}</ref> |
Darwin became engrossed in meticulous microscopic examination, tracing the complicated mechanisms of flowers that attracted insects by their nectar so that the insects transported pollen to cross-pollinate other plants, and on 19 July he told Hooker, "I am intensely interested on subject, just as at a game of chess."<ref name=volume8/><ref name=Letter2871>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2871.html |title=Darwin Correspondence Project - Letter 2871 — Darwin, C. R. to Hooker, J. D., 19 (July 1860) |accessdate=2009-02-03}}</ref> In September, he "dissected with the greatest interest" and wrote, "The contrivances for insect fertilisation in Orchids are multiform & truly wonderful & beautiful."<ref name=Letter2920>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2920.html |title=Darwin Correspondence Project - Letter 2920 — Darwin, C. R. to Gordon, George (b), 17 Sept (1860) |accessdate=2009-02-06}}</ref> By October, he had "a large mass of notes with many new facts", but set them aside "convinced that I ought to work on ''Variation'' & not amuse myself with interludes".<ref name=Letter2956>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-2956.html |title=Darwin Correspondence Project - Letter 2956 — Darwin, C. R. to Oliver, Daniel, 20 Oct (1860) |accessdate=2009-02-06}}</ref> |
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===Botany as recreation === |
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[[File:Fertilisation of Orchids figure 4c.jpg|thumb|right|alt=Moth head with long proboscis protruding and curled down, attached to several pairs of pollen masses.|Head of a moth with its [[proboscis]] laden with several pairs of [[Pollinium|pollinia]]]] |
[[File:Fertilisation of Orchids figure 4c.jpg|thumb|right|alt=Moth head with long proboscis protruding and curled down, attached to several pairs of pollen masses.|Head of a moth with its [[proboscis]] laden with several pairs of [[Pollinium|pollinia]]]] |
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The completed Orchis paper came to 140 folio pages, and Darwin decided against presenting it at the [[Linnean Society of London]], thinking of publishing a pamphlet instead. He offered the draft to [[John Murray (publisher)|John Murray]] who agreed to publish it as a book.<ref name=Letter3263>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3263.html |title=Darwin Correspondence Project - Letter 3263 — Darwin, C. R. to Hooker, J. D., 24 Sept (1861) |accessdate=2009-02-05}}</ref> Although Darwin feared a lack of public interest, he hoped it would serve to "illustrate how Natural History may be worked under the belief of the modification of Species."<ref name=Letter3264>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3264.html |title=Darwin Correspondence Project - Letter 3264 — Darwin, C. R. to Murray, John (b), 24 Sept (1861) |accessdate=2009-02-05}}</ref> In discussions with Asa Gray about [[natural theology]], he wrote that "it really seems to me incredibly monstrous to look at an orchid as created as we now see it. Every part reveals modification on modification."<ref name=Letter3283>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3283.html#back-mark-3283.f7 |title=Darwin Correspondence Project - Letter 3283 — Darwin, C. R. to Gray, Asa, [after 11 Oct 1861] |format= |work= |accessdate=2009-02-04}}</ref> |
The completed Orchis paper came to 140 folio pages, and Darwin decided against presenting it at the [[Linnean Society of London]], thinking of publishing a pamphlet instead. He offered the draft to [[John Murray (publisher)|John Murray]] who agreed to publish it as a book.<ref name=Letter3263>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3263.html |title=Darwin Correspondence Project - Letter 3263 — Darwin, C. R. to Hooker, J. D., 24 Sept (1861) |accessdate=2009-02-05}}</ref> Although Darwin feared a lack of public interest, he hoped it would serve to "illustrate how Natural History may be worked under the belief of the modification of Species."<ref name=Letter3264>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3264.html |title=Darwin Correspondence Project - Letter 3264 — Darwin, C. R. to Murray, John (b), 24 Sept (1861) |accessdate=2009-02-05}}</ref> In discussions with Asa Gray about [[natural theology]], he wrote that "it really seems to me incredibly monstrous to look at an orchid as created as we now see it. Every part reveals modification on modification."<ref name=Letter3283>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3283.html#back-mark-3283.f7 |title=Darwin Correspondence Project - Letter 3283 — Darwin, C. R. to Gray, Asa, [after 11 Oct 1861] |format= |work= |accessdate=2009-02-04}}</ref> |
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Darwin began to include women who were botany enthusiasts in his correspondence. As a popular and acceptable activity, botany had been taken up by many middle class ladies. On the recommendation of [[John Lindley]], Darwin wrote to [[Lady Dorothy Nevill]] who responded generously by sending numerous exotic orchids |
Darwin began to include women who were botany enthusiasts in his correspondence. As a popular and acceptable activity, botany had been taken up by many middle class ladies. On the recommendation of [[John Lindley]], Darwin wrote to [[Lady Dorothy Nevill]] who responded generously by sending numerous exotic orchids.<ref name=b170/><ref name=Letter3402>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3402.html |title=Darwin Correspondence Project - Letter 3402 — Nevill, D. F. to Darwin, C. R., (before 22 Jan 1862) |accessdate=2009-06-25}}</ref> |
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===Linnean Society paper=== |
===Linnean Society paper=== |
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As soon as the book was published, botanists responded favourably. Hooker told Darwin that the book showed him to be "out of sight the best Physiological observer & experimenter that Botany ever saw",<ref name=Letter3624>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3624.html |title=Darwin Correspondence Project - Letter 3624 — Hooker, J. D. to Darwin, C. R., 28 June 1862 |accessdate=2009-06-25}}</ref> and was glad to note that two leading traditional botanists had come over to evolution; "Bentham & Oliver are quite struck up in a heap with your book & delighted beyond expression".<ref name=b194>{{harvnb|Browne|2002|p=194}}</ref><ref name=Letter3527>{{citation |url= http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3527.html |title=Darwin Correspondence Project - Letter 3527 — Hooker, J. D. to Darwin, C. R., (17 May 1862) |accessdate=2009-06-25}}</ref> [[Daniel Oliver]] thought it "very extraordinary", and even Darwin's old beetle-hunting rival [[Cardale Babington|Charles Babington]], now professor of botany at the [[University of Cambridge]] and inclined to oppose natural selection, called it "exceedingly interesting and valuable... highly satisfactory in all respects. The results are most curious and the skill shown in discovering them equally so."<ref name=b193>{{harvnb|Browne|2002|pp=193–194}}</ref><ref name=Letter3566>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3566.html |title=Darwin Correspondence Project - Letter 3566 — Babington, C. C. to Darwin, C. R., 22 May 1862 |accessdate=2009-06-25}}</ref> [[George Bentham]] praised its value in opening "a new field for observing the wonderful provisions of Nature... a new and unexpected track to guide us in the explanation of phenomena which had before that appeared so irreconcileable with the ordinary prevision and method shown in the organised world."<ref name=Letter3554>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3554.html |title=Darwin Correspondence Project - Letter 3554 — Bentham, George to Darwin, C. R., 15 May 1862 |accessdate=2009-06-25}}</ref><ref name=b194/> |
As soon as the book was published, botanists responded favourably. Hooker told Darwin that the book showed him to be "out of sight the best Physiological observer & experimenter that Botany ever saw",<ref name=Letter3624>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3624.html |title=Darwin Correspondence Project - Letter 3624 — Hooker, J. D. to Darwin, C. R., 28 June 1862 |accessdate=2009-06-25}}</ref> and was glad to note that two leading traditional botanists had come over to evolution; "Bentham & Oliver are quite struck up in a heap with your book & delighted beyond expression".<ref name=b194>{{harvnb|Browne|2002|p=194}}</ref><ref name=Letter3527>{{citation |url= http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3527.html |title=Darwin Correspondence Project - Letter 3527 — Hooker, J. D. to Darwin, C. R., (17 May 1862) |accessdate=2009-06-25}}</ref> [[Daniel Oliver]] thought it "very extraordinary", and even Darwin's old beetle-hunting rival [[Cardale Babington|Charles Babington]], now professor of botany at the [[University of Cambridge]] and inclined to oppose natural selection, called it "exceedingly interesting and valuable... highly satisfactory in all respects. The results are most curious and the skill shown in discovering them equally so."<ref name=b193>{{harvnb|Browne|2002|pp=193–194}}</ref><ref name=Letter3566>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3566.html |title=Darwin Correspondence Project - Letter 3566 — Babington, C. C. to Darwin, C. R., 22 May 1862 |accessdate=2009-06-25}}</ref> [[George Bentham]] praised its value in opening "a new field for observing the wonderful provisions of Nature... a new and unexpected track to guide us in the explanation of phenomena which had before that appeared so irreconcileable with the ordinary prevision and method shown in the organised world."<ref name=Letter3554>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3554.html |title=Darwin Correspondence Project - Letter 3554 — Bentham, George to Darwin, C. R., 15 May 1862 |accessdate=2009-06-25}}</ref><ref name=b194/> |
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The success of the book in botanical circles widened when Bentham |
The success of the book in botanical circles widened when Bentham praised the book in his presidential address to the [[Linnean Society of London|Linnean Society]] on 24 May 1862,<ref name=volume10/> and in his address there in 1863 stated that "Mr Darwin has shown how changes ''may'' take place", describing the book as "an unimpeachable example of a legitimate hypothesis" in compliance with [[John Stuart Mill]]'s scientific method. This endorsement favourably influenced [[Miles Joseph Berkeley]], [[Charles Victor Naudin]], [[Alphonse Pyramus de Candolle]], [[Jean Louis Armand de Quatrefages de Bréau|Jean Louis Quatrefages]] and [[Charles Daubeny]].<ref name=b194/><ref name=Letter4217>{{cite web |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-4217.html |title=Darwin Correspondence Project - Letter 4217 — Darwin, C. R. to Bentham, George, 19 June (1863) |accessdate=2009-07-28}}</ref> |
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In June 1862, Darwin welcomed favourable reviews in the press and wrote to Hooker; "Well my orchis-book is a success (but I do not know whether it sells) after cursing my folly in writing it".<ref name=Letter3628>{{citation |url= http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3628.html |title=Darwin Correspondence Project - Letter 3628 — Darwin, C. R. to Hooker, J. D., 30 (June 1862) |accessdate=2009-02-07}}</ref> He told his publisher, "The Botanists praise my Orchid-book to the skies", and to [[Asa Gray]] he said, "I am fairly astonished at the success of my book with botanists." Darwin's geologist friend [[Charles Lyell]] gave it enthusiastic praise, "next to the ''Origin'', as the most valuable of all Darwin's works." However, the book gained little attention from the general public, and in September Darwin told his cousin [[William Darwin Fox|Fox]], "Hardly any one not a botanist, except yourself, as far as I know, has cared for it."<ref name=reviews>{{harvnb|Darwin|1887|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1452.3&pageseq=282 270–276]}}</ref> The book baffled a general public more interested in controversy over gorillas and cavemen. There were some reviews in gardening magazines, but few natural philosphers or zoologists noticed the book, and hardly any learned appraisals appeared.<ref name=b193/> |
In June 1862, Darwin welcomed favourable reviews in the press and wrote to Hooker; "Well my orchis-book is a success (but I do not know whether it sells) after cursing my folly in writing it".<ref name=Letter3628>{{citation |url= http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3628.html |title=Darwin Correspondence Project - Letter 3628 — Darwin, C. R. to Hooker, J. D., 30 (June 1862) |accessdate=2009-02-07}}</ref> He told his publisher, "The Botanists praise my Orchid-book to the skies", and to [[Asa Gray]] he said, "I am fairly astonished at the success of my book with botanists." Darwin's geologist friend [[Charles Lyell]] gave it enthusiastic praise, "next to the ''Origin'', as the most valuable of all Darwin's works." However, the book gained little attention from the general public, and in September Darwin told his cousin [[William Darwin Fox|Fox]], "Hardly any one not a botanist, except yourself, as far as I know, has cared for it."<ref name=reviews>{{harvnb|Darwin|1887|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1452.3&pageseq=282 270–276]}}</ref> The book baffled a general public more interested in controversy over gorillas and cavemen. There were some reviews in gardening magazines, but few natural philosphers or zoologists noticed the book, and hardly any learned appraisals appeared.<ref name=b193/> |
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{{quote|For some years before 1862 I had specially attended to the fertilisation of our British orchids; and it seemed to me the best plan to prepare as complete a treatise on this group of plants as well as I could, rather than to utilise the great mass of matter which I had slowly collected with respect to other plants. My resolve proved a wise one; for since the appearance of my book, a surprising number of papers and separate works on the fertilisation of all kinds of flowers have appeared; and these are far better done than I could possibly have effected. The merits of poor old Sprengel, so long overlooked, are now fully recognised many years after his death.<ref name=bio/> }} |
{{quote|For some years before 1862 I had specially attended to the fertilisation of our British orchids; and it seemed to me the best plan to prepare as complete a treatise on this group of plants as well as I could, rather than to utilise the great mass of matter which I had slowly collected with respect to other plants. My resolve proved a wise one; for since the appearance of my book, a surprising number of papers and separate works on the fertilisation of all kinds of flowers have appeared; and these are far better done than I could possibly have effected. The merits of poor old Sprengel, so long overlooked, are now fully recognised many years after his death.<ref name=bio/> }} |
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Prominent biologists [[Hermann Müller (botanist)|Hermann Müller]], Friedrich Hildebrand and Severin Axell in Europe, [[Asa Gray]] and Charles Robertson in North America, and [[Fritz Müller]] in Brazil, took up the study of reproductive [[ecology]] using a Darwinian approach. In Italy, Federigo Delpino adopted the theory of descent but like Sprengel had a [[teleology|teleological]] approach and explained the mechanisms of flowers by the intervention of a "psychovitalistic intelligence". Delpino coined many of the terms still in use, such as [[pollination syndrome]] and [[ornithophily]]. There was an enormous increase in knowledge during this period.<ref name=bl57>{{harvnb|Vogel|1996|pp=57–58}}</ref> In 1874 Asa Gray paid tribute to Darwin's work on orchids for |
Prominent biologists [[Hermann Müller (botanist)|Hermann Müller]], Friedrich Hildebrand and Severin Axell in Europe, [[Asa Gray]] and Charles Robertson in North America, and [[Fritz Müller]] in Brazil, took up the study of reproductive [[ecology]] using a Darwinian approach. In Italy, Federigo Delpino adopted the theory of descent but like Sprengel had a [[teleology|teleological]] approach and explained the mechanisms of flowers by the intervention of a "psychovitalistic intelligence". Delpino coined many of the terms still in use, such as [[pollination syndrome]] and [[ornithophily]]. There was an enormous increase in knowledge during this period.<ref name=bl57>{{harvnb|Vogel|1996|pp=57–58}}</ref> In 1874 Asa Gray paid tribute to Darwin's work on orchids for explaining "all these and other extraordinary structures, as well as of the arrangement of blossoms in general, and even the very meaning and need of sexual propagation". He credited Darwin with establishing the understanding that "Nature abhors close fertilization".<ref name=vw51>{{harvnb|van Wyhe|2008|p=51}}</ref><ref>{{harvnb|Gray|1874|p=[http://darwin-online.org.uk/content/frameset?itemID=A230&viewtype=text&pageseq=4 478]}}</ref> }} |
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{{quote|the explanation of all these and other extraordinary structures, as well as of the arrangement of blossoms in general, and even the very meaning and need of sexual propagation... The aphorism 'Nature abhors close fertilization,' and the demonstration of the principle, belong to our age, and to Mr. Darwin. To have originated this, and also the principle of Natural Selection—the truthfulness and importance of which are evident the moment it is apprehended—and to have applied these principles to the system of nature in such a manner as to make, within a dozen years, a deeper impression upon natural history than has been made since Linnaeus, are ample title for one man's fame.<ref name=vw51>{{harvnb|van Wyhe|2008|p=51}}</ref><ref>{{harvnb|Gray|1874|p=[http://darwin-online.org.uk/content/frameset?itemID=A230&viewtype=text&pageseq=4 478]}}</ref> }} |
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By the end of the 19th century, there were so many uncritical and unproven speculations about floral mechanisms that floral ecology became discredited. In the 1920s, it was revived with new developments in detailed analyses of insects' senses, led by researchers [[Frederic Clements]], [[Karl von Frisch]] and others. Their experiments made new findings, including the discovery that some [[insect]]s have [[ultraviolet]] vision, and information about [[bee learning and communication]]. Modern floral ecology has been reinvigorated by its relevance for evolutionary studies.<ref name=bl57/> |
By the end of the 19th century, there were so many uncritical and unproven speculations about floral mechanisms that floral ecology became discredited. In the 1920s, it was revived with new developments in detailed analyses of insects' senses, led by researchers [[Frederic Clements]], [[Karl von Frisch]] and others. Their experiments made new findings, including the discovery that some [[insect]]s have [[ultraviolet]] vision, and information about [[bee learning and communication]]. Modern floral ecology has been reinvigorated by its relevance for evolutionary studies.<ref name=bl57/> |
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==Further research by Darwin== |
==Further research by Darwin== |
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[[File:Darwin's greenhouse.JPG|thumb|right|alt=Lean-to greenhouses against a brick wall, with an entrance door and water butt at the nearest end and trees in the background|Darwin's greenhouse at [[Down House]] was extended to provide hothouses where he spent an hour or so every morning and afternoon, examining plants and planning future experiments.<ref name=b211/>]] |
[[File:Darwin's greenhouse.JPG|thumb|right|alt=Lean-to greenhouses against a brick wall, with an entrance door and water butt at the nearest end and trees in the background|Darwin's greenhouse at [[Down House]] was extended to provide hothouses where he spent an hour or so every morning and afternoon, examining plants and planning future experiments.<ref name=b211/>]] |
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Darwin had "found the study of orchids eminently useful in showing me how nearly all parts of the flower are coadapted for fertilisation by insects, & therefore the result of n. selection,–even most trifling details of structure".<ref name=Letter3472>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3472.html#back-mark-3472.f7 |title=Darwin Correspondence Project - Letter 3472 — Darwin, C. R. to Hooker, J. D., 14 Mar (1862) |accessdate=2009-06-25}}</ref> His own interest in orchids and in fertilisation of plants by insects continued. Having previously borrowed the use of a neighbour's hot-house, |
Darwin had "found the study of orchids eminently useful in showing me how nearly all parts of the flower are coadapted for fertilisation by insects, & therefore the result of n. selection,–even most trifling details of structure".<ref name=Letter3472>{{citation |url=http://www.darwinproject.ac.uk/darwinletters/calendar/entry-3472.html#back-mark-3472.f7 |title=Darwin Correspondence Project - Letter 3472 — Darwin, C. R. to Hooker, J. D., 14 Mar (1862) |accessdate=2009-06-25}}</ref> His own interest in orchids and in fertilisation of plants by insects continued. Having previously borrowed the use of a neighbour's hot-house, he was persuaded by the neighbour's helpful gardener to have his own built at Down House, and used to spend time in it each day.<ref name=b211>{{harvnb|Browne|2002|pp=211–212}}</ref><ref>{{harvnb|Desmond|Moore|1991|p=513}}<br>{{citation |url= http://www.darwinproject.ac.uk/darwinletters/calendar/entry-4009.html |title=Darwin Correspondence Project - Letter 4009 — Darwin, C. R. to Hooker, J. D., 24(–5) Feb (1863) |accessdate=2009-06-25}}<br>{{harvnb|Darwin|1887|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1452.1&pageseq=132 114–116], [http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1452.1&pageseq=162 144–145]}}</ref> |
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A chance observation "thoroughly aroused" Darwin's attention to a surprising decrease in vigour of the offspring of [[Linaria vulgaris]] following only one instance of self-fertilisation, and after eleven years of experimental work he published ''[[The Effects of Cross and Self Fertilisation in the Vegetable Kingdom]]'' in 1876 as "a complement to the 'Fertilisation of Orchids,' because it shows how important are the results of cross-fertilisation which are ensured by the mechanisms described in that book." |
A chance observation "thoroughly aroused" Darwin's attention to a surprising decrease in vigour of the offspring of [[Linaria vulgaris]] following only one instance of self-fertilisation, and after eleven years of experimental work he published ''[[The Effects of Cross and Self Fertilisation in the Vegetable Kingdom]]'' in 1876 as "a complement to the 'Fertilisation of Orchids,' because it shows how important are the results of cross-fertilisation which are ensured by the mechanisms described in that book."<ref name=fd288/> He told a friend "I cannot endure doing nothing", and resumed his work on orchids, assisted in his research by his son [[Francis Darwin]]. He almost completely rewrote the book with a considerable amount of new material, much of which was contributed by [[Fritz Müller]]. The revised edition was published in 1877.<ref name=b412>{{harvnb|Browne|2002|pp=412–417}}</ref><ref>{{harvnb|Darwin|1887|p=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1452.3&pageseq=298 286]}}</ref> Francis Darwin recalled a reference to Orchid-work made in an 1880 letter, near the end of his father's life, in which Darwin characteristically reminisced about "delight in the observations which preceded its publication, not to the applause which followed it": |
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{{quote|They are wonderful creatures, these Orchids, and I sometimes think with a glow of pleasure, when I remember making out some little point in their method of fertilisation.<ref>{{harvnb|Darwin|1887|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1452.3&pageseq=300 288–290]}}</ref> }} |
{{quote|They are wonderful creatures, these Orchids, and I sometimes think with a glow of pleasure, when I remember making out some little point in their method of fertilisation.<ref name=fd288>{{harvnb|Darwin|1887|pp=[http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F1452.3&pageseq=300 288–290]}}</ref> }} |
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==Commemoration of Darwin's work on orchids== |
==Commemoration of Darwin's work on orchids== |
Revision as of 22:45, 28 July 2009
Author | Charles Darwin |
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Language | English |
Subject | Natural selection Botany |
Publisher | John Murray |
Publication date | 15 May 1862 |
Publication place | United Kingdom |
Media type | Print (Hardback) |
ISBN | N/A Parameter error in {{ISBNT}}: invalid character |
Fertilisation of Orchids is a book by Charles Darwin published in 1862 under the full explanatory title On the various contrivances by which British and foreign orchids are fertilised by insects, and on the good effects of intercrossing.[1] It followed On the Origin of Species and was his first detailed demonstration of the power of natural selection, explaining how complex ecological relationships resulted in the coevolution of orchids and insects. Field studies and practical scientific investigations that Darwin began as a recreation, a pastime giving relief from the drudgery of writing, developed into enjoyable and challenging experiments, aided by his family, village friends and a widening circle of correspondents across Britain and worldwide. It tapped into a vogue at the time for growing exotic orchids.
The book influenced botanists, and revived interest in the neglected idea that insects played a part in pollinating flowers. It opened up the new area of study of pollination research and reproductive ecology directly related to Darwin's ideas of evolution, and supported his view that natural selection led to a variety of forms through the important benefits achieved by cross-fertilisation. The general public showed less interest, and sales of the book were low, but it established Darwin as a leading botanist and was the first of a series of books on his innovative investigations into plants.
Orchids described how the relationship between insects and plants resulted in the beautiful and complex forms which natural theology attributed to a designer. By showing how practical adaptations develop from cumulative minor variations of parts of the flowers to suit new purposes, Darwin countered the prevailing view that beautiful organisms were the handiwork of the Creator. Darwin's painstaking observations, experiments and detailed dissection of the flowers explained previously unknown features, such as the puzzle of Catasetum which had been thought to have three completely different species of flowers on the same plant, and made testable predictions. His proposal that the long nectary of Angraecum sesquipedale meant that there must be a moth with an equally long proboscis was controversial at the time, but was confirmed in 1903 when Xanthopan morgani was found in Madagascar.
Background
Charles Darwin grew up with an interest in natural history, and as a student at the University of Cambridge he became a pupil and close friend of botany professor John Stevens Henslow. The year that he graduated, Darwin was given a place as a gentleman naturalist and geologist on the Beagle voyage, a voyage that lasted five years. By the time of his return in October 1836, he doubted the doctrine that species were fixed and unchanging. Expert information about his specimens inspired the inception of his theory of natural selection in 1838. Darwin took on the editing and publication of expert reports, collected in the Zoology of the Voyage of H.M.S. Beagle, at the same time as writing books on geology, beginning with The Structure and Distribution of Coral Reefs. His "species work" was his "prime hobby" in the background to this writing, and became an extensive research programme during the twenty years before he published his theory.[2]
Insect fertilisation of plants
From the outset, Darwin's speculations on the origin of species convinced him that cross-fertilisation played an important part in keeping specific forms consistent. He rejected the doctrine that the characteristics of a species were invariable, and was aware from animal husbandry that inbreeding could lead to changes, often deleterious. He thought that natural outbreeding through cross-fertilisation would keep wild species homogenous and vigorous. Cross-fertilisation would give an evolutionary advantage by spreading favourable changes throughout a reproductive community. His ideas were contrary to the common supposition that plants were usually self-fertilising, so every summer he investigated the contribution of insect pollination to the cross-pollination of flowers.[3][4]
In the summer of 1841, Charles and Emma Darwin moved from the turmoil of London to the countryside village of Downe and their family home, Down House. He wrote, "The flowers are here very beautiful".[5] At about the same time, Darwin followed the recommendation of his friend, the leading botanist Robert Brown, and read Das entdeckte Geheimnis der Natur im Bau und in der Befruchtung der Blumen (The Secret of Nature in the Form and Fertilisation of Flowers Discovered[6]).[3] This little known book, published in 1793 by Christian Konrad Sprengel but never translated into English, introduced the idea that flowers were created by God to fulfill a teleological purpose: insects would act as "living brushes" to cross-fertilise plants in a symbiotic relationship. This functional view was rejected and mostly forgotten, as it contradicted beliefs that flowers had been created for beauty and were generally self-fertilising. For Darwin, evolution gave new meaning to Sprengel's research into mechanisms for cross-fertilisation. He welcomed its support for his supposition that flowering plants tended to escape disadvantages caused to their offspring by self-fertilisation,[7] and by 1845 he had verified many of Sprengel's observations.[8]
A favourite walk took the Darwin family to a beautiful spot above the quiet Cudham valley, teeming with orchids including Cephalanthera, Neottia, fly orchids and musk orchids. They called this place "Orchis Bank", and the whole family became involved in Darwin's researches.[9] Darwin watched orchids every summer, but in twenty years, only on two occasions (when he noticed butterflies "sucking O. pyramidalis and Gymnadenia") did he see insects visiting flowers.[10] In 1854 Darwin began full time work on the origin of species.[11] He examined orchids and counted how often one or both pollinia had been removed from their flowers which indicated that they had been visited by insects.[12] He experimented on insect pollination to investigate if field crops such as Fabaceae yielded more vigourous offspring when they were cross-fertilised, and published letters about his rather inconclusive results in The Gardeners' Chronicle in 1857 and 1858. He then applied Sprengel's methods to empirical research on orchids.[4][13] Despite delays caused by recurring illness, he made good progress on writing his planned "Big Book" on evolution, but Alfred Russel Wallace's letter prompted joint publication of both of their theories of natural selection in 1858, and Darwin quickly wrote On the Origin of Species as an abstract of his theory, published on 22 November 1859.[11] In this book, he gave credence to Sprengel's ideas on the advantages of "intercrossing".[14] and noted, "Many of our orchidaceous plants absolutely require the visits of moths to remove their pollen-masses and thus to fertilise them".[15] He then introduced for the first time his new concept of the process of coevolution, describing the co–adaption of bumblebees and red clover and speculating "how a flower and a bee might slowly become, either simultaneously or one after the other, modified and adapted in the most perfect manner to each other, by the continued preservation of individuals presenting mutual and slightly favourable deviations of structure." This was a theme he developed in his orchid book.[16][17]
Research, writing and publication
After On the Origin of Species was published, Darwin became involved in producing revisions for new editions as well as working on Variation of Animals and Plants Under Domestication, as the first part of his planned "Big Book".[18][19]
By the spring of 1860 he had become tired of the grind of writing, and needed something fresh and interesting to study. While out on a search for orchids he noticed a sundew, collected it and tried to feed it insects, beginning a long-term study of insectivorous plants. He investigated other botanical questions raised by his ideas of natural selection, including the advantages of sexual dimorphism in primulas, and the adaptive mechanisms that ensure cross-pollination in orchids.[20][21] As an enthusiastic practical scientist, such investigations gave him a strong sense of personal enjoyment. He relished pitting his wits against nature, and following lucky hunches. His theory was a way of looking at the world, enabling him to find creative solutions to problems that traditional approaches could not solve. He later wrote, "I am like a gambler, & love a wild experiment."[22][23]
Around the end of April 1860, Darwin discussed insect pollination with his friend Joseph Dalton Hooker,[24] and mentioned the bee orchid.[25] Darwin corresponded with Hooker's assistant Daniel Oliver, the senior curator at Kew Gardens, who became a follower of Darwin's ideas.[22] At the start of June, Darwin wrote to The Gardeners' Chronicle asking for readers' observations on how bee or fly orchids were fertilised. His letter described the mechanisms for insect fertilisation he had discovered in common British orchids, and reported his investigations and experiments that found that pollen masses were removed from Orchis morio and Orchis mascula plants in the open, but left in their pouches in adjacent plants under a glass bell jar.[26] He wrote to American botanist Asa Gray that he had been "so struck with admiration at the contrivances, that I have sent notice to Gardeners Chronicle",[27] and made similar enquiries of other experts.[28]
Darwin became engrossed in meticulous microscopic examination, tracing the complicated mechanisms of flowers that attracted insects by their nectar so that the insects transported pollen to cross-pollinate other plants, and on 19 July he told Hooker, "I am intensely interested on subject, just as at a game of chess."[21][29] In September, he "dissected with the greatest interest" and wrote, "The contrivances for insect fertilisation in Orchids are multiform & truly wonderful & beautiful."[30] By October, he had "a large mass of notes with many new facts", but set them aside "convinced that I ought to work on Variation & not amuse myself with interludes".[31]
Botany as recreation
In the course of 1861, botany became a preoccupation for Darwin, with his projects becoming serious scientific pursuits. He continued his study of orchids through the summer, writing to any possible supplier of specimens that he had yet to examine.[32] Field naturalists, botanists and country gentry sent specimens from across the British Isles. He collected his own specimens, tramping round the countryside with tin cans and biscuit boxes, then getting his gardeners to pot up the specimens. His family joined in with the collecting, and neighbours also contributed to the research. As Darwin only had a cold greenhouse, a friend on the other side of the village who had a hot-house let him use it and gave the services of his gardener to look after the delicate specimens. Darwin's aim was to show how the complex structures and life cycles of the plants could be explained by natural selection rather than regarded as the handiwork of God, and he saw the huge variety of flowers as a collection of ad hoc evolutionary adaptations.[33] In June, he described his examination of bee orchids as a passion,[34] and his work on insect fertilisation of orchids as "beautiful facts".[35]
There were several replies to Darwin's enquiry in The Gardeners' Chronicle seeking evidence to support his idea that pollen masses attached themselves to a convenient place on an insect's back or head, usually its proboscis, to transport the pollen to another flower. One envelope appeared to be empty when it arrived at Down House, but when he looked further before discarding it he found several insect mouthparts with pollen masses attached.[36] To help their daughter Henrietta convalesce from illness, the Darwins arranged to spend two months in Torquay. Darwin wrote:
I have, owing to many interruptions, not been going on much with my regular work (though I have done the very heavy jobs of variation of Pigeons, Fowls, Ducks, Rabbits Dogs &c) but have been amusing myself with miscellaneous work.— I have been very lucky & have now examined almost every British Orchid fresh, & when at sea-side shall draw up rather long paper on the means of their fertilisation for Linn. Socy & I cannot fancy anything more perfect than the many curious contrivances.[37]
He sought advice on obtaining the exotic South American Catasetum to see it eject pollen-masses, as "I am got intensely interested on subject & think I understand pretty well all the British species."[37] They went to Torquay on 1 July,[38] and he began writing his Orchid paper.[39] By 10 August, he feared his paper would run "to 100 M.S. folio pages!!! The beauty of the adaptations of parts seems to me unparalleled..... I marvel often as I think over the diversity & perfection of the contrivances."[40]
They returned to Downe on 27 August,[38] and he again wrote to the Gardeners' Chronicle appealing for assistance as he was "very anxious to examine a few exotic forms."[41] His requests to the wealthy enthusiasts who had taken up the fashionable pursuit of growing rare orchids brought large numbers of specimens. These would be a test of his theory: previously aspects such as coloration of plants and animals had often been regarded as having no adaptive function. For example, Thomas Henry Huxley was strongly influenced by German idealism and in 1856 had asked if it was "to be supposed for a moment that the beauty of colour and outline ... are any good to the animals? ... Who has ever dreamed of finding an utilitarian purpose in the forms and colours of flowers... ?" Darwin had, and in the orchids he tackled the most difficult case. His ideas would transform the way naturalists thought about coloration.[42][43]
The completed Orchis paper came to 140 folio pages, and Darwin decided against presenting it at the Linnean Society of London, thinking of publishing a pamphlet instead. He offered the draft to John Murray who agreed to publish it as a book.[44] Although Darwin feared a lack of public interest, he hoped it would serve to "illustrate how Natural History may be worked under the belief of the modification of Species."[45] In discussions with Asa Gray about natural theology, he wrote that "it really seems to me incredibly monstrous to look at an orchid as created as we now see it. Every part reveals modification on modification."[46]
Darwin began to include women who were botany enthusiasts in his correspondence. As a popular and acceptable activity, botany had been taken up by many middle class ladies. On the recommendation of John Lindley, Darwin wrote to Lady Dorothy Nevill who responded generously by sending numerous exotic orchids.[33][47]
Linnean Society paper
Despite delays to the orchid book due to illness, Darwin continued to "look at it as a hobby-horse, which has given me great pleasure to ride".[48] He was particularly astounded by the long spur of the Angraecum sesquipedale flowers, one of the orchids sent by the distinguished horticulturist James Bateman,[49] and wrote to Hooker "Good Heavens what insect can suck it[?]"[50]
By November, a specimen of the exotic South American Catasetum orchid that Hooker had given to Darwin had shown its "truly marvellous" mechanism that shot out a pollinium at any insect touching a part of the flower "with sticky gland always foremost".[51] This plant had astonished botanists in 1836 when Robert Hermann Schomburgk stated that he had seen one plant growing three distinct flowers which usually grew separately and had wrongly been categorised as three distinct genera, namely Catasetum tridentatum, Monachanthus viridis, and Myanthus barbatus. John Lindley had remarked that "such cases shake to the foundation all our ideas of the stability of genera and species." One of Darwin's correspondents told of delight at growing a beautiful specimen of Myanthus barbatus imported from Demerara, then dismay when the plant flowered the next year as a simple Catasetum.[52]
In view of this interest, Darwin prepared a paper on Catasetum as an extract from his forthcoming book, and this was read to the Linnean Society of London on 3 April 1862.[53] Darwin solved the puzzle by showing that the three flowers were the male, female, and hermaphrodite forms of a single species, but as they differed so much from each other, they had been classified as different genera.[54]
Publication
On 9 February 1862, Darwin sent his manuscript off to his publisher John Murray incomplete, as he was still working on the last chapter. While anxious over whether the book would sell, he could "say with confidence that the M.S. contains many new & very curious facts & conclusions".[55] When the book was printed, he sent out presentation copies to all the individuals and societies who had helped him with his investigations, and to eminent botanists in Britain and abroad for review.[54]
On the various contrivances by which British and foreign orchids are fertilised by insects, and on the good effects of intercrossing was published on 15 May 1862.[1] In August, Darwin was "well contented with the sale of 768 copies; I shd. hope & expect that the remainder will ultimately be sold",[56] but the book sold slowly and less than 2,000 copies of the first edition were printed. An expanded edition translated into French was published in Paris in 1870, and in 1877, Murray brought out a revised and expanded second edition with the shortened title The various contrivances by which orchids are fertilised by insects. This was also published by D. Appleton & Company of New York in 1877, and German translation was published in the same year. Despite being well praised by botanists, only about 6,000 copies of the English editions had sold before 1900.[1]
Content
In the introduction, Darwin explained his aim of meeting complaints that detailed support for his theory had been lacking in On the Origin of Species. He had chosen orchids as "amongst the most singular and most modified forms in the vegetable kingdom" in the hope of inspiring work on other species, and felt that "the study of organic beings may be as interesting to an observer who is fully convinced that the structure of each is due to secondary laws, as to one who views every trifling detail of structure as the result of the direct interposition of the Creator." He gave due credit to previous authors who had described the agency of insects in fertilising orchids, and all who had helped him.[57]
British orchids
In the first chapter Darwin describes the British orchids he had studied, giving detailed explanations of their various mechanisms for transferring pollen to insects.[58]
The first mechanism described is that of Orchis mascula, which serves as an introduction to the explanation of other Orchidaceae. In the upper part of the flower the male organ has two pollen masses on stalks down to adhesive balls in a cup. When an insect is attracted to land on the large projecting lower petal, the labellum, and pushes its head and proboscis into the nectary of the flower, it breaks the cup and the adhesive balls attach the pollen masses to the insect. As the insect flies off, each stalk rotates the pollen mass downwards and forwards so that when the insect lands on another flower the pollen masses attached to the insect pass under the male organ and leave pollen on the female organ, achieving cross fertilisation.[58] Darwin envisaged:
A poet might imagine, that whilst the pollinia are borne from flower to flower through the air, adhering to a moth's body, they voluntarily and eagerly place themselves, in each case, in that exact position in which alone they can hope to gain their wish and perpetuate their race."[59]
While the bee orchid showed adaptation for self-fertilisation, its mechanism would also enable the occasional cross-fertilisation, creating the biological diversity that Darwin felt was needed for vigorous survival, not provided by self-fertilisation.[60] At Torquay Darwin had watched bees visiting spires of Spiranthes flowers, starting at the lower flowers and working their way up to the topmost flowers that attached pollen clusters to the bees, ready for them to fly to the lower flowers on another plant which had already shed their own pollen, and fertilise them, adding "to her store of honey" while perpetuating the flowers "which will yield honey to future generations of bees".[61]
Exotic orchids
The book moves on to the various foreign orchids Darwin had received from others. His experiments showed that the "astonishing length" of the nectary hanging from Angraecum sesquipedale flowers implied the need for an as yet unknown moth with an equally long proboscis.[62]
Darwin described "the most remarkable of all Orchids", Catasetum, and showed how in these flowers, "as throughout nature, pre-existing structures and capacities [had been] utilised for new purposes". He explained the mechanism by which it fired its sticky pollen mass at an insect that touched an "antenna" on the flower, referring to experiments imitating its action using a whalebone spring. He vividly illustrated how the flower ejected the pollinium with considerable force: "I touched the antennæ of C. callosum whilst holding the flower at about a yard's distance from the window, and the pollinium hit the pane of glass, and adhered to the smooth vertical surface by its adhesive disc."[62]
Final chapter
Darwin noted that the essential nectar, secreted to attract insects, seemed also in some cases to act as an excretion: "It is in perfect accordance with the scheme of nature, as worked out by natural selection, that matter excreted to free the system from superfluous or injuring substances should be utilised for purposes of the highest importance."[63] Homologies of the orchid flowers of orchids showed them all to be based on "fifteen groups of vessels, arranged three within three, in alternating order". He disparaged the idea that this was an "ideal type" fixed by the Omnipotent Creator, but attributed it instead to its "descent from some monocotyledonous plant, which, like so many other plants of the same division, possessed fifteen organs, arranged alternately three within three in five whorls; and that the now wonderfully changed structure of the flower is due to a long course of slow modification,— each modification having been preserved which was useful to each plant, during the incessant changes to which the organic and the inorganic world has been exposed".[64]
Describing the final end state of the whole flower cycle as the production of seed, he set out a simple experiment where he took a ripe seed capsule and arranged the seeds in a line, then counted the seeds in one-tenth of an inch (2.5 mm). By multiplication he found that each plant produced enough seeds to plant an acre of ground (0.4 ha), and the great grandchildren of a single plant could "carpet the entire surface of the land throughout the globe" if unchecked.[65]
His conclusion was that the "contrivances and beautiful adaptations" slowly acquired through slight variations, subjected to natural selection "under the complex and ever-varying conditions of life", far transcended the most fertile imagination. The mechanisms to transport the pollen of one flower or of one plant to another flower or plant underlined the importance of cross-fertilisation: "For may we not further infer as probable, in accordance with the belief of the vast majority of the breeders of our domestic productions, that marriage between near relatives is likewise in some way injurious,—that some unknown great good is derived from the union of individuals which have been kept distinct for many generations?"[66]
Reception
As soon as the book was published, botanists responded favourably. Hooker told Darwin that the book showed him to be "out of sight the best Physiological observer & experimenter that Botany ever saw",[67] and was glad to note that two leading traditional botanists had come over to evolution; "Bentham & Oliver are quite struck up in a heap with your book & delighted beyond expression".[68][69] Daniel Oliver thought it "very extraordinary", and even Darwin's old beetle-hunting rival Charles Babington, now professor of botany at the University of Cambridge and inclined to oppose natural selection, called it "exceedingly interesting and valuable... highly satisfactory in all respects. The results are most curious and the skill shown in discovering them equally so."[70][71] George Bentham praised its value in opening "a new field for observing the wonderful provisions of Nature... a new and unexpected track to guide us in the explanation of phenomena which had before that appeared so irreconcileable with the ordinary prevision and method shown in the organised world."[72][68]
The success of the book in botanical circles widened when Bentham praised the book in his presidential address to the Linnean Society on 24 May 1862,[54] and in his address there in 1863 stated that "Mr Darwin has shown how changes may take place", describing the book as "an unimpeachable example of a legitimate hypothesis" in compliance with John Stuart Mill's scientific method. This endorsement favourably influenced Miles Joseph Berkeley, Charles Victor Naudin, Alphonse Pyramus de Candolle, Jean Louis Quatrefages and Charles Daubeny.[68][73]
In June 1862, Darwin welcomed favourable reviews in the press and wrote to Hooker; "Well my orchis-book is a success (but I do not know whether it sells) after cursing my folly in writing it".[74] He told his publisher, "The Botanists praise my Orchid-book to the skies", and to Asa Gray he said, "I am fairly astonished at the success of my book with botanists." Darwin's geologist friend Charles Lyell gave it enthusiastic praise, "next to the Origin, as the most valuable of all Darwin's works." However, the book gained little attention from the general public, and in September Darwin told his cousin Fox, "Hardly any one not a botanist, except yourself, as far as I know, has cared for it."[75] The book baffled a general public more interested in controversy over gorillas and cavemen. There were some reviews in gardening magazines, but few natural philosphers or zoologists noticed the book, and hardly any learned appraisals appeared.[70]
Theological responses
Though the book countered the prevailing natural theology and its teleological argument of design in nature, the Saturday Review thought that the approach taken in the book would escape the angry polemics aroused by On the Origin of Species. The Literary Churchman welcomed "Mr. Darwin's expression of admiration at the contrivances in orchids", only complaining that it was too indirect a way of saying "O Lord, how manifold are Thy works!"[75] Darwin regarded these theological views as irritating misunderstandings, but wrote to Asa Gray describing his approach as a "flank movement on the enemy." By showing that the "wonderful contrivances" of the orchid have discoverable evolutionary histories, Darwin was countering claims by natural theologians that the organisms were examples of the perfect work of the Creator.[70][77]
There was considerable controversy about Darwin's prediction that a moth would be found in Madagascar with a long proboscis matching the nectary of Angraecum sesquipedale. An anonymous article in the Edinburgh Review of October 1862 by George Campbell, 8th Duke of Argyll, argued that Darwin's wording implied purpose, and concluded that "We know, too, that these purposes and ideas are not our own, but the ideas and purposes of Another." He considered Darwin's explanations the "most unsatisfactory conjectures", and raised obscure metaphysical objections while supporting a kind of creative evolutionism. Emma Darwin thought that although Argyll was "quite opposed" to Darwin's views, "he praises the Orchids in such an enthusiastic way that he will do it a good turn." Darwin was delighted to find that a well written article "smashing" Argyll's review was by one of Darwin's own nephews. Argyll went on to cleverly ridicule Darwin's ideas, particularly the prediction of a moth with a long proboscis, in his 1867 book The Reign of Law. In response, Alfred Russel Wallace produced a detailed explanation of how the nectary could have evolved through natural selection, and in 1903 Xanthopan morgani was found in Madagascar as Darwin had expected.[76][78][79]
Influence
The publication of Darwin's work on insect fertilisation of orchids led almost immediately to research by many other naturalists into the evolution of specialisation, and studies of coevolution which in some cases analysed other taxa.[80] In his autobiography, Darwin modestly recalled how this work had revived interest in Christian Konrad Sprengel's neglected ideas:[3]
For some years before 1862 I had specially attended to the fertilisation of our British orchids; and it seemed to me the best plan to prepare as complete a treatise on this group of plants as well as I could, rather than to utilise the great mass of matter which I had slowly collected with respect to other plants. My resolve proved a wise one; for since the appearance of my book, a surprising number of papers and separate works on the fertilisation of all kinds of flowers have appeared; and these are far better done than I could possibly have effected. The merits of poor old Sprengel, so long overlooked, are now fully recognised many years after his death.[3]
Prominent biologists Hermann Müller, Friedrich Hildebrand and Severin Axell in Europe, Asa Gray and Charles Robertson in North America, and Fritz Müller in Brazil, took up the study of reproductive ecology using a Darwinian approach. In Italy, Federigo Delpino adopted the theory of descent but like Sprengel had a teleological approach and explained the mechanisms of flowers by the intervention of a "psychovitalistic intelligence". Delpino coined many of the terms still in use, such as pollination syndrome and ornithophily. There was an enormous increase in knowledge during this period.[81] In 1874 Asa Gray paid tribute to Darwin's work on orchids for explaining "all these and other extraordinary structures, as well as of the arrangement of blossoms in general, and even the very meaning and need of sexual propagation". He credited Darwin with establishing the understanding that "Nature abhors close fertilization".[82][83] }}
By the end of the 19th century, there were so many uncritical and unproven speculations about floral mechanisms that floral ecology became discredited. In the 1920s, it was revived with new developments in detailed analyses of insects' senses, led by researchers Frederic Clements, Karl von Frisch and others. Their experiments made new findings, including the discovery that some insects have ultraviolet vision, and information about bee learning and communication. Modern floral ecology has been reinvigorated by its relevance for evolutionary studies.[81]
Further research by Darwin
Darwin had "found the study of orchids eminently useful in showing me how nearly all parts of the flower are coadapted for fertilisation by insects, & therefore the result of n. selection,–even most trifling details of structure".[85] His own interest in orchids and in fertilisation of plants by insects continued. Having previously borrowed the use of a neighbour's hot-house, he was persuaded by the neighbour's helpful gardener to have his own built at Down House, and used to spend time in it each day.[84][86]
A chance observation "thoroughly aroused" Darwin's attention to a surprising decrease in vigour of the offspring of Linaria vulgaris following only one instance of self-fertilisation, and after eleven years of experimental work he published The Effects of Cross and Self Fertilisation in the Vegetable Kingdom in 1876 as "a complement to the 'Fertilisation of Orchids,' because it shows how important are the results of cross-fertilisation which are ensured by the mechanisms described in that book."[87] He told a friend "I cannot endure doing nothing", and resumed his work on orchids, assisted in his research by his son Francis Darwin. He almost completely rewrote the book with a considerable amount of new material, much of which was contributed by Fritz Müller. The revised edition was published in 1877.[88][89] Francis Darwin recalled a reference to Orchid-work made in an 1880 letter, near the end of his father's life, in which Darwin characteristically reminisced about "delight in the observations which preceded its publication, not to the applause which followed it":
They are wonderful creatures, these Orchids, and I sometimes think with a glow of pleasure, when I remember making out some little point in their method of fertilisation.[87]
Commemoration of Darwin's work on orchids
Kent Wildlife Trust operates Downe Bank nature reserve which forms part of the Downe Bank and High Elms Site of Special Scientific Interest, and includes the area known to Darwin's family as "Orchis Bank". They note how "Darwin’s observations of local orchids and their insect pollinators gave him evidence of co-evolution and led to the publication of his famous book Fertilisation of Orchids in 1862."[90] Experts have identified "Orchis Bank" as the species-rich setting described in the closing paragraph of On the Origin of Species,[91] where Darwin wrote:
It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us."[92]
Darwin's home together with its surroundings which have been called his landscape laboratory, including specifically "Orchis Bank", was nominated in January 2009 for designation as a World Heritage Site.[93] The bid has been made by a partnership led by the London Borough of Bromley (which now includes Downe) and a decision is to be made by the World Heritage Site Committee in 2010.[94]
The influence of Darwin's work was commemorated in the Smithsonian Institution's 15th Annual Orchid Show, Orchids Through Darwins Eyes, 24 January to 26 April 2009.[95]
Notes
- ^ a b c Darwin Online: Fertilisation of Orchids, retrieved 2009-02-02
{{citation}}
: Cite has empty unknown parameter:|coauthors=
(help) - ^ van Wyhe 2008, pp. 14–16, 31, 44–45
- ^ a b c d Darwin 1958, pp. 127–128
- ^ a b Vogel 1996, pp. 56–57
- ^ Darwin & Seward 1903, pp. 31–33
- ^ Vogel 1996, p. 44
- ^ Vogel 1996, pp. 44–57
- ^ Darwin Correspondence Project - Letter 889 — Darwin, C. R. to Hooker, J. D., (11–12 July 1845), retrieved 2009-07-20
- ^ Darwin 1887, p. 116
- ^ Darwin 1862, pp. 34–39
- ^ a b van Wyhe 2008, pp. 45–47
- ^ Darwin 1862, pp. 57–60
- ^ Darwin 1857, p. 725,
Darwin 1858, pp. 828–829 - ^ Darwin 1859, pp. 98–99, 145–146
- ^ Darwin 1859, pp. 73–74
- ^ Thompson 1994, pp. 24–25
- ^ Darwin 1859, pp. 94–95
- ^ Browne 2002, pp. 100–102
- ^ van Wyhe 2008, pp. 52–53
- ^ Browne 2002, pp. 146–148
- ^ a b Darwin Correspondence Project - The correspondence of Charles Darwin, volume 8: 1860, retrieved 2009-02-03
- ^ a b Browne 2002, pp. 166–167
- ^ Darwin Correspondence Project - Letter 4061 — Darwin, C. R. to Hooker, J. D., 26 (Mar 1863), retrieved 2009-06-25
- ^ Darwin Correspondence Project - Letter 2770 — Darwin, C. R. to Hooker, J. D., 27 April (1860), retrieved 2009-02-03
- ^ Darwin Correspondence Project - Letter 2776 — Darwin, C. R. to Hooker, J. D., 30 Apr (1860), retrieved 2009-02-03
- ^ Darwin Correspondence Project - Letter 2826 — Darwin, C. R. to Gardeners' Chronicle, (4 or 5 June 1860), retrieved 2009-02-03
- ^ Darwin Correspondence Project - Letter 2825 — Darwin, C. R. to Gray, Asa, 8 June (1860), retrieved 2009-02-04
- ^ Darwin Correspondence Project - Letter 2829 — Darwin, C. R. to Stainton, H. T., 11 June (1860), retrieved 2009-02-04
- ^ Darwin Correspondence Project - Letter 2871 — Darwin, C. R. to Hooker, J. D., 19 (July 1860), retrieved 2009-02-03
- ^ Darwin Correspondence Project - Letter 2920 — Darwin, C. R. to Gordon, George (b), 17 Sept (1860), retrieved 2009-02-06
- ^ Darwin Correspondence Project - Letter 2956 — Darwin, C. R. to Oliver, Daniel, 20 Oct (1860), retrieved 2009-02-06
- ^ Darwin Correspondence Project - The correspondence of Charles Darwin, volume 9: 1861, retrieved 2009-02-06
- ^ a b Browne 2002, pp. 170–172
- ^ Darwin Correspondence Project - Letter 3174 — Darwin, C. R. to More, A. G., 2 June 1861, retrieved 2009-02-04
- ^ Darwin Correspondence Project - Letter 3176 — Darwin, C. R. to Gray, Asa, 5 June (1861), retrieved 2009-02-04
- ^ Browne 2002, p. 174
- ^ a b Darwin Correspondence Project - Letter 3190 — Darwin, C. R. to Hooker, J. D., 19 June (1861), retrieved 2009-02-04
- ^ a b Darwin 2006, pp. 38 verso–40 verso
- ^ Darwin Correspondence Project - Letter 3216 — Darwin, C. R. to Gray, Asa, 21 July (1861), retrieved 2009-02-04
- ^ Darwin Correspondence Project - Letter 3221 — Darwin, C. R. to Hooker, J. D., (28 July – 10 Aug 1861), retrieved 2009-02-05
- ^ Darwin Correspondence Project - Letter 3252 — Darwin, C. R. to Gardeners' Chronicle, (before 14 Sept 1861), retrieved 2009-02-05
- ^ Desmond & Moore 1991, pp. 509–510
- ^ Cronin 1993, p. 102
- ^ Darwin Correspondence Project - Letter 3263 — Darwin, C. R. to Hooker, J. D., 24 Sept (1861), retrieved 2009-02-05
- ^ Darwin Correspondence Project - Letter 3264 — Darwin, C. R. to Murray, John (b), 24 Sept (1861), retrieved 2009-02-05
- ^ Darwin Correspondence Project - Letter 3283 — Darwin, C. R. to Gray, Asa, [after 11 Oct 1861], retrieved 2009-02-04
- ^ Darwin Correspondence Project - Letter 3402 — Nevill, D. F. to Darwin, C. R., (before 22 Jan 1862), retrieved 2009-06-25
- ^ Darwin Correspondence Project - Letter 3404 — Darwin, C. R. to Gray, Asa, 22 Jan (1862), retrieved 2009-02-07
- ^ Darwin Correspondence Project - Letter 3411 — Darwin, C. R. to Hooker, J. D., 25 Jan (1862), retrieved 2009-02-09
- ^ Darwin Correspondence Project - Letter 3421 — Darwin, C. R. to Hooker, J. D., 30 Jan (1862), retrieved 2009-02-12
- ^ Darwin Correspondence Project - Letter 3305 — Darwin, C. R. to Hooker, J. D., 1 Nov [1861], retrieved 2009-02-07
- ^ Darwin Correspondence Project - Letter 3407 — Rogers, John (a) to Darwin, C. R., 22 Jan 1862, retrieved 2009-02-07
- ^ Darwin 1862a
- ^ a b c Darwin Correspondence Project - The correspondence of Charles Darwin, volume 10: 1862, retrieved 2009-02-07
- ^ Darwin Correspondence Project - Letter 3442 — Darwin, C. R. to Murray, John (b), 9 (Feb 1862), retrieved 2009-02-07
- ^ Darwin Correspondence Project - Letter 3699 — Darwin, C. R. to Murray, John (b), 24 Aug (1862), retrieved 2009-02-05
- ^ Darwin 1862, pp. 1–4
- ^ a b Darwin 1862, pp. 9–19
- ^ Darwin 1862, pp. 91–93
- ^ Darwin 1862, pp. 63–72
- ^ Darwin 1862, pp. 127–129
- ^ a b Darwin 1862, pp. 197–203 Cite error: The named reference "orchids211" was defined multiple times with different content (see the help page).
- ^ Darwin 1862, pp. 278–279
- ^ Darwin 1862, pp. 305–307
- ^ Darwin 1862, pp. 343–346
- ^ Darwin 1862, pp. 346–360
- ^ Darwin Correspondence Project - Letter 3624 — Hooker, J. D. to Darwin, C. R., 28 June 1862, retrieved 2009-06-25
- ^ a b c Browne 2002, p. 194
- ^ Darwin Correspondence Project - Letter 3527 — Hooker, J. D. to Darwin, C. R., (17 May 1862), retrieved 2009-06-25
- ^ a b c Browne 2002, pp. 193–194
- ^ Darwin Correspondence Project - Letter 3566 — Babington, C. C. to Darwin, C. R., 22 May 1862, retrieved 2009-06-25
- ^ Darwin Correspondence Project - Letter 3554 — Bentham, George to Darwin, C. R., 15 May 1862, retrieved 2009-06-25
- ^ "Darwin Correspondence Project - Letter 4217 — Darwin, C. R. to Bentham, George, 19 June (1863)". Retrieved 2009-07-28.
- ^ Darwin Correspondence Project - Letter 3628 — Darwin, C. R. to Hooker, J. D., 30 (June 1862), retrieved 2009-02-07
- ^ a b Darwin 1887, pp. 270–276
- ^ a b Kritsky 1991
- ^ Darwin Correspondence Project - Letter 3662 — Darwin, C. R. to Gray, Asa, 23(–4) July (1862), retrieved 2008-03-09
- ^ Browne 2002, pp. 194–195
- ^ Darwin 1887, pp. 274–275
- ^ Thompson 1994, pp. 28–29
- ^ a b Vogel 1996, pp. 57–58
- ^ van Wyhe 2008, p. 51
- ^ Gray 1874, p. 478
- ^ a b Browne 2002, pp. 211–212
- ^ Darwin Correspondence Project - Letter 3472 — Darwin, C. R. to Hooker, J. D., 14 Mar (1862), retrieved 2009-06-25
- ^ Desmond & Moore 1991, p. 513
Darwin Correspondence Project - Letter 4009 — Darwin, C. R. to Hooker, J. D., 24(–5) Feb (1863), retrieved 2009-06-25
Darwin 1887, pp. 114–116, 144–145 - ^ a b Darwin 1887, pp. 288–290
- ^ Browne 2002, pp. 412–417
- ^ Darwin 1887, p. 286
- ^ Darwin at Downe - Downe Bank, retrieved 2009-07-28
- ^ Darwin 200: Celebrating Charles Darwin's bicentenary - Darwin at Downe, Kent, retrieved 2009-02-12
- ^ Darwin 1859, p. 489
- ^ Darwin's home nominated as world heritage site | Science, The Guardian, retrieved 2009-02-12
{{citation}}
: Italic or bold markup not allowed in:|publisher=
(help) - ^ Downe Bank - Kent Wildlife Trust, retrieved 2009-02-12
- ^ Orchids Through Darwin's Eyes, Smithsonian Institution, retrieved 2009-02-12
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- Thompson, John L. (1994), The coevolutionary process, Chicago: University of Chicago Press, ISBN 0-226-79760-0, retrieved 2009-07-27
- van Wyhe, John (2008), Darwin: The Story of the Man and His Theories of Evolution, London: Andre Deutsch Ltd (published 1 September 2008), ISBN 0-233-00251-0
- Vogel, Stefan (1996), Barrett, Spencer C. H.; Lloyd, David W. (eds.), Floral biology: studies on floral evolution in animal-pollinated plants, London: Chapman & Hall, pp. 44–60, ISBN 0-412-04341-6, retrieved 2009-07-20
External links
- The Complete Works of Charles Darwin Online gives online access to Darwin's writings: see Darwin Online: Fertilisation of Orchids for links to English, French and German editions of the book.