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Darwin Correspondence Project

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Darwin Correspondence Project
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Forms of flowers

Summary

Darwin’s book The different forms of flowers on plants of the same species, published in 1877, investigated the structural differences in the sexual organs of flowers of the same species. It drew on and expanded five articles Darwin had published on the…

Matches: 15 hits

  • … male flowers on separate plants) and also noted that their pollen differed in size and shape. He …
  • … of Primrose & Cowslip with short pistils & large-grained pollen are rather more fertile …
  • … of my experiments lead me to suspect that the large-grained pollen suits the long pistils & the …
  • … I think I have made out their good or meaning clearly. The pollen of A is fitted for stigma of B …
  • … both terms referred to the fertilisation of one form with pollen from the same form. At this late …
  • … two forms and that one of these was absolutely sterile with pollen from the same form, while the …
  • … explained to Gray, ‘ I have lately been putting the pollen of the two forms on the division of the …
  • … me as truly wonderful, that the stigma distinguishes the pollen; & is penetrated by the tubes of …
  • … he told Hooker, ‘ In function, but not in appearance, the pollen of these two forms, as tested by …
  • … is so frequent in truly hermaphrodite groups; namely the pollen & stigma of each flower being …
  • … of the plant, with dotted lines indicating which pollen must be applied to each stigma to produce …
  • … He told Gray in October 1865 that with respect to its own pollen, the long-styled form was …
  • … plants raised from Dimorphic species fertilized by their own pollen, are themselves generally …
  • … in a few specimens. It is necessary to compare size of pollen grains & state of stigma ’. …
  • … ‘I will rank no plant as dimorphic without comparing pollen-grains & stigmas’. When Hermann …

Charles Harrison Blackley

Summary

You may not have heard of Charles Harrison Blackley (1820–1900), but if you are one of the 15 million people in the UK who suffer from hay fever, you are indebted to him. For it was he who identified pollen as the cause of the allergy. Darwin was…

Matches: 11 hits

  • … fever, you are indebted to him. For it was he who identified pollen as the cause of the allergy, and …
  • … 5 July 1873 Darwin wrote again, saying:  ‘The power of pollen in exciting the skin & mucous …
  • … changes in his own symptoms, that he was able to single out pollen as the only credible cause. …
  • … He also experimented with fresh, dry and extracts of pollen, administered to his nose, mouth, eyes …
  • … writes: Perhaps where grass is cut & dried; some pollen of the entomophilous division …
  • … was fascinated by Blackley’s experiments testing whether pollen could be carried large distances in …
  • … p. 5). Darwin gave a further example of how coniferous pollen could be carried for hundreds of miles …
  • … with carbolic acid to deter insects.  He concluded that in pollen seasons much higher levels were …
  • … from hay fever in large cities far away from sources of pollen. In his later work, possibly …
  • … Blackley tried to find out the smallest amount of pollen that would initiate and maintain the …
  • … recommending spending summers in suitable locations to avoid pollen.  But his lasting contribution …

Cross and self fertilisation

Summary

The effects of cross and self fertilisation in the vegetable kingdom, published on 10 November 1876, was the result of a decade-long project to provide evidence for Darwin’s belief that ‘‘Nature thus tells us, in the most emphatic manner, that she abhors…

Matches: 20 hits

  • … flowers and the physiological effects of different forms of pollen. Although many plants that Darwin …
  • … many of these were nevertheless fertile with their own pollen. He set out to compare several …
  • … of the young plants when raised from a pistil fertilized by pollen from the same flower, & from …
  • … that Darwin would confirm that this poppy shed its pollen immediately after the flower opened, …
  • … since even those flowers to which he applied foreign pollen had probably already been self …
  • … on which he commented, ‘This complete infertility with own pollen could hardly have remained …
  • … you w d  care, is that a great excess of, or very little pollen produced not the least difference …
  • … On the other hand seeds from this plant, fertilised by pollen from the same flower, weigh less, …
  • … beginning to suspect that the insects which could transfer pollen in sweet peas simply did not exist …
  • … mignonette ( Reseda odorata ) was absolutely sterile with pollen from same plant in spite of the …
  • … there sh d  be some difference in ovules & contents of pollen-grains (for the tubes penetrate …
  • … the same plant!’ ( To J. D. Hooker, 21 May [1868] ) Pollen tubes, or rapidly elongating vegetative …
  • … ovary of a flower; they are triggered to elongate when the pollen touches the stigmatic surface. …
  • … at the lessened fertility when he pollinated plants using pollen from other plants of the same …
  • … the early part of the flowering season quite sterile with pollen from the same plant, though fertile …
  • … as adults forever fixed in close proximity to others, so pollen from widely separated flowers could …
  • … stylar forms of flowers, Darwin had referred to unions where pollen from one form had been applied …
  • … that some forms were absolutely sterile with their own pollen while others had varying degrees of …
  • … Ernst Haeckel, ‘It is really wonderful what an effect pollen from a distinct seedling plant which …
  • … forms of flowers that showed sterility could exist when pollen from one form was applied to the same …

A fly on the flower: From Hermann Müller, 23 October 1867

Summary

In March 1867, Hermann Müller, a young teacher of natural sciences at a provincial Realschule (a type of secondary school that emphasised the natural sciences) in Lippstadt in the Prussian province of Westphalia, sent Darwin two papers on the mosses of…

Matches: 4 hits

  • … order to observe their adaptations for collecting nectar and pollen. A letter he wrote in October …
  • … of the hoverfly mouthparts that are specially adapted for pollen eating. Müller’s discovery seemed …
  • … as pseudotracheae), which were the perfect size for holding pollen grains. He further noted, having …
  • … in different species, depending on the size of the pollen eaten by each type of fly. It is amazing …

Floral Dimorphism

Summary

Sources|Discussion Questions|Experiment Floral studies In 1877 Darwin published a book that included a series of smaller studies on botanical subjects. Titled The different forms of flowers on plants of the same species, it consisted primarily of…

Matches: 2 hits

  • … class was able to readily observe the two sizes of style and pollen within these plants. To observe …
  • … .0254 mm.”[1] Darwin suggested that the difference in pollen sizes between the short and long-styled …

Essay: Evolutionary teleology

Summary

—by Asa Gray EVOLUTIONARY TELEOLOGY When Cuvier spoke of the ‘combination of organs in such order that they may be in consistence with the part which the animal has to play in Nature,’ his opponent, Geoffroy St.-Hilaire, rejoined, ‘I know nothing of…

Matches: 14 hits

  • … meaning. One good illustration of it is furnished by the pollen of flowers. The seeming waste of …
  • … ’ which every one has heard of. Myriads upon myriads of pollen-grains (each an elaborate organic …
  • … a violet, in which there are not many times more grains of pollen produced than there are of seeds …
  • … other flowers also, provided with a large surplus of pollen, and endowed (as the others are not) …
  • … to certain insects, which are thereby induced to convey this pollen from blossom to blossom, that it …
  • … of which are committed to insects, the likelihood that much pollen may be left behind or lost in the …
  • … in orchis-flowers is accounted for by the fact that the pollen is packed in coherent masses, all …
  • … against it when it sucks nectar from the flower, and so the pollen will be bodily conveyed from …
  • … case, that of pine-trees, the vast superabundance of pollen would be sheer waste if the intention …
  • … ’ as the means, no one is entitled to declare that pine-pollen is in wasteful excess. The cheapness …
  • … involved in similar difficulty. The superabundance of the pollen of pine-trees above referred to, …
  • … In the analogous instance of willows a diminished amount of pollen is correlated with direct …
  • … difference in the conveyance would reduce the quantity of pollen produced. It is, we know, in the …
  • … work and material; but why should it begin to produce less pollen? But this is as nothing compared …

Orchids

Summary

Sources|Discussion Questions|Experiment A project to follow On the Origin of Species Darwin began to observe English orchids and collect specimens from abroad in the years immediately following the publication of On the Origin of Species. Examining…

Matches: 2 hits

  • … , which ejects its pollinia with a sticky gland so that the pollen will stick on the head of an …
  • … of the genera Catasetum . This genera of orchid uses a pollen release mechanism that ejects …

From morphology to movement: observation and experiment

Summary

Darwin was a thoughtful observer of the natural world from an early age. Whether on a grand scale, as exemplified by his observations on geology, or a microscopic one, as shown by his early work on the eggs and larvae of tiny bryozoans, Darwin was…

Matches: 2 hits

  • … adapted for cross fertilisation (sticky glands containing pollen masses) or self fertilisation …
  • … to communicate their observations on what happened to the pollen masses. Darwin continued to …

Hermann Müller

Summary

Hermann (Heinrich Ludwig Hermann) Müller, was born in Mühlberg near Erfurt in 1829. He was the younger brother of Fritz Müller (1822–97). Following the completion of his secondary education at Erfurt in 1848, he studied natural sciences at Halle and Berlin…

Matches: 2 hits

  • … at the ways insects were adapted to gather nectar and pollen, just as flowers were adapted to …
  • … in hoverflies that allowed them to consume large amounts of pollen. Further research along these …

Orchids

Summary

Why Orchids? Darwin  wrote in his Autobiography, ‘During the summer of 1839, and, I believe, during the previous summer, I was led to attend to the cross-fertilisation of flowers by the aid of insects, from having come to the conclusion in my…

Matches: 5 hits

  • … puzzles me.— The Fly-Ophrys seems hardly ever to get its pollen masses moved at all, & the …
  • … agency—another part, namely the natural falling out of the pollen-masses, being adapted for self …
  • … in which I ask for information on what kinds of moths the pollen-masses of Orchids have been found …
  • … Hooker, ‘ I shall never rest till I see a Catasetum eject pollen-masses, & a Mormodes twist its …
  • … not only because of its remarkable ability to eject its pollen masses like a catapult, but also …

The evolution of honeycomb

Summary

Honeycombs are natural engineering marvels, using the least possible amount of wax to provide the greatest amount of storage space, with the greatest possible structural stability. Darwin recognised that explaining the evolution of the honey-bee’s comb…

Matches: 2 hits

  • … built back to back, and are used to store honey, nectar, and pollen, and to provide a nursery for …
  • … cells stored the greatest possible amount of honey and pollen with the least possible expenditure of …

Fool's experiments

Summary

‘I love fools' experiments. I am always making them’, was one of the most interesting things the zoologist E. Ray Lankester ever heard Darwin say. ‘A great deal might be written as comment on that statement’, Lankester later recorded, but he limited…

Matches: 1 hits

  • … to Lankester involved placing under a bell jar some pollen from a male flower together with, but …

Darwin in letters, 1864: Failing health

Summary

On receiving a photograph from Charles Darwin, the American botanist Asa Gray wrote on 11 July 1864: ‘the venerable beard gives the look of your having suffered, and … of having grown older’.  Because of poor health, Because of poor health, Darwin…

Matches: 4 hits

  • … whereby each form achieved the highest fertility only with pollen from the other two forms. The …
  • … collecting and measuring flower parts, drawing pictures of pollen-grains, stigmas, and anthers, and …
  • … writing on 14 April [1864] , ‘I can do as much pollen work as ever you like’. Comments on William’s …
  • … Crüger confirmed both his observation of  Catasetum pollen adhering to a humble-bee’s back, …

What is an experiment?

Summary

Darwin is not usually regarded as an experimenter, but rather as an astute observer and a grand theorist. His early career seems to confirm this. He began with detailed note-taking, collecting and cataloguing on the Beagle, and edited a descriptive zoology…

Matches: 2 hits

  • … aim; reproducing natural processes by hand (applying the pollen of one flower to another, immersing …
  • … and counting natural productions (stamens, pistils, pollen seeds; visits of bees to flowers); …

Darwin in letters, 1862: A multiplicity of experiments

Summary

1862 was a particularly productive year for Darwin. This was not only the case in his published output (two botanical papers and a book on the pollination mechanisms of orchids), but more particularly in the extent and breadth of the botanical experiments…

Matches: 2 hits

  • … to observe the effects of repeated crossing with own-form pollen. He also began systematically to …
  • … of styles and stamens and differently coloured and sized pollen grains; only an elaborate system of …

Species and varieties

Summary

On the origin of species by means of natural selection …so begins the title of Darwin’s most famous book, and the reader would rightly assume that such a thing as ‘species’ must therefore exist and be subject to description. But the title continues, …or…

Matches: 2 hits

  • … long pistils; he also noted differences in the size of the pollen in the two forms. Over the next …
  • … was self-sterile, while another was fertile with its own pollen. There seemed to be no universal law …

Scientific Practice

Summary

Specialism|Experiment|Microscopes|Collecting|Theory Letter writing is often seen as a part of scientific communication, rather than as integral to knowledge making. This section shows how correspondence could help to shape the practice of science, from…

Matches: 1 hits

  • … fertility of orchids he has self-pollinated and crossed with pollen of other species. …

Scientific Networks

Summary

Friendship|Mentors|Class|Gender In its broadest sense, a scientific network is a set of connections between people, places, and things that channel the communication of knowledge, and that substantially determine both its intellectual form and content,…

Matches: 3 hits

  • … He discusses how dipterous insects are adapted to eating pollen rather than only to sucking nectar. …
  • … flowers. One is ripening. Dissection of the other shows the pollen accomplishes fertilisation …
  • … interpretation of Acropera pollination is ingenious. Pollen-tubes of some cleistogamous flowers …

Darwin in letters, 1877: Flowers and honours

Summary

Ever since the publication of Expression, Darwin’s research had centred firmly on botany. The year 1877 was no exception. The spring and early summer were spent completing Forms of flowers, his fifth book on a botanical topic. He then turned to the…

Matches: 4 hits

  • … . ‘I will rank no plant as dimorphic without comparing pollen-grains & stigmas’, Darwin …
  • … and painstaking measurements of the size and number of pollen-grains, Darwin compared the fertility …
  • … especially with the aid of insects: the size and shape of pollen-grains, the position of stigmatic …
  • … life to which all organisms are subjected, by producing both pollen and seeds’ ( Forms of flowers …

A tale of two bees

Summary

Darwinian evolution theory fundamentally changed the way we understand the environment and even led to the coining of the word 'ecology'. Darwin was fascinated by bees: he devised experiments to study the comb-building technique of honey bees and…

Matches: 1 hits

  • … is, depressing the keel so that the mechanism which caused pollen to be deposited on the bee would …
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