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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Fertilisation of Orchids | 4/9 | https://en.wikipedia.org/wiki/Fertilisation_of_Orchids | reference | science, encyclopedia | 2026-05-05T08:30:38.882356+00:00 | kb-cron |
The orchid book was delayed because of illness, but Darwin continued to "look at it as a hobby-horse, which has given me great pleasure to ride". He was particularly astounded by the long spur of the Angraecum sesquipedale flowers, one of the orchids sent by the distinguished horticulturist James Bateman, and wrote to Hooker "Good Heavens what insect can suck it[?]" By November, a specimen of the exotic South American Catasetum orchid Hooker had given to Darwin had shown its "truly marvellous" mechanism, by which it shot out a pollinium at any insect touching a part of the flower "with sticky gland always foremost". 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. In view of this interest, Darwin prepared a paper on Catasetum as an extract from his forthcoming book, which was read to the Linnean Society of London on 3 April 1862. 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.
=== Publication === Darwin sent the incomplete manuscript to his publisher John Murray on 9 February 1862, while he was still working on the last chapter. Although anxious that the book might not sell, he could "say with confidence that the M.S. contains many new & very curious facts & conclusions". 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. On 15 May 1862 the book was published under the full title of On the Various Contrivances by Which British and Foreign Orchids Are Fertilised by Insects, and On the Good Effects of Intercrossing. In August, Darwin was "well contented with the sale of 768 copies; I shd. hope & expect that the remainder will ultimately be sold", 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 a German translation was published in the same year. Despite being well praised by botanists, only about 6,000 copies of the English editions had been sold by 1900.
== Content == Darwin set out a detailed study of common descent with modifications by expanding on the theme of coevolution between local populations of insects and flowering plants that he had briefly discussed in On the Origin of Species. He examined numerous ways in which orchids vary, showing how they had diverged and developed specialised pollen-dispersal mechanisms. The intricate morphology and anatomy of each flower was carefully described. Apparently trivial details were examined in relation to natural selection to demonstrate how slight variations in similar structures of closely related flowers led to specialised modifications that provided various pollinators (insects) with different ways to cross-fertilise. The mass of descriptive detail was a great achievement, but the result is demanding to read. In the introduction, Darwin explained his aim of meeting complaints that detailed support for his theory was lacking in On the Origin of Species. He chose orchids for his subject 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.
=== British orchids ===
In the first chapter Darwin described the British orchids he had studied, giving detailed explanations of their various mechanisms for transferring pollen to insects. 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 a petal shelters the male organ which has two packages of pollen grains, held together by thin elastic threads. These pollen masses stand side by side and have stalks down to adhesive balls in a cup which keeps them moist and sticky. When an insect lands on the large projecting lower petal, the labellum, and pushes its head and proboscis into the centre of the flower and down to the nectary, it breaks the cup and the adhesive balls attach the pollen masses to the front of 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. Darwin envisaged: