It was fitting that in the 200th anniversary year of his birth, and the 150th of the publication of his major work, we should hear a talk on Charles Darwin, which was given by Dr Jane McLauchlin. Jane gave us a resume of his career, but with emphasis on his later work, especially with plants.
Charles, a nephew of Josiah Wedgwood, was born to wealth, but was a restless youth with no serious ambitions. He was persuaded to study medicine at Edinburgh, but soon gave this up and transferred to Cambridge to study theology, which was just as unappealing to him. But at Cambridge he met people who influenced the course of his life, none more so than Adam Sedgwick, the geologist, who became a friend and mentor. Sedgwick it was who persuaded him to apply for the post of companion to the captain of the Royal Navy ship “Beagle”, on a long surveying trip around the world. His father wasn't keen, but Uncle Josiah approved, thinking the voyage would get the restlessness out of his system.
Thus it was that he set sail in 1831 on what was strictly a cartographic operation, not a voyage of exploration, but which gave him the opportunity to take trips ashore to collect specimens of fauna and flora, particularly in South America. He was away for five years, for which time he kept a diary, and after which he produced a report, The Voyage of the Beagle, in 1839.
In that year he also married his cousin Emma Wedgwood, both of them 30 years old and lifelong friends, and she highly educated. They lived initially in Gower Street, London, in a house now the site of University College's Biology Department. But by 1842 they had tired of London, and moved to Down House in Kent, small by their standards but with a large garden. Here they raised ten children, and Darwin spent much of his time conducting experiments and corresponding with other thinkers.
He wrote a number of books, revealing discoveries on such matters as the origin of coral reefs, and the life cycle of barnacles. All the time, the idea was forming in his mind that species were created by slow changes, not by instantaneous creation, and he was amassing a great deal of evidence for this. So it was a shock when in 1858 one of his correspondents, Alfred Wallace, sent him a paper that was almost a precis of his own ideas, but lacking the detailed evidence. He hastily put together a paper of his own and both papers were read at the same meeting of the Linnean Society, with Wallace's agreement and support.
History was made, and so was Darwin's name, but the rest is not history. He published in the next year his great volume On the Origin of Species, but his daily life did not change dramatically. He continued to live the rest of his life at Down House with his family, and continued his experiments and correspondence. He also wrote ten more books, less often mentioned, but all important contributions to science. Seven of them concerned plants, and Jane told us of these works in some detail.
The first was on orchids, in which Darwin demonstrated their many and strange methods of pollination. Then came a study of climbing plants, with examination of the different ways in which they cling to their support, such as spirals, `irritables', hooks and tendrils, and rootlets. He suggested that any genus of plants is capable of producing a climbing species.
Animals and plants under domestication were the subject of another book, in which he showed how `unnatural selection', in horticulture and breeding, speed up what is basically the natural way of things. (He was conducting his own experiments with peas etc. whilst Mendel was doing even more complex ones at the same time, unnoticed.)
Darwin's tome on carnivorous plants was unexpectedly `brought to life' on the night of the talk by David Taylor, who had brought along his own pristine copy, a presentation copy to a member of the Gladstone family! In it, Darwin details his results from feeding different foods to the plants, and his study of how they digest their prey.
A study of fertilisation followed, of crossing, and of self-fertilisation. But he needed his cousin Galton to do the maths and statistics for this, which he admitted were beyond him. In his next book he showed that flowers of the same species, such as the primrose, can have two forms. He studied primrose hybrids, and conducted experiments on their fertility. This was followed by work on violets, and he discovered that if the early flowers fail to be fertilised by insects, self-fertilising flowers appear later in the season.
In 1880 he studied the growth of roots and shoots, and made experimental attempts to thwart their progress. He also showed that leaves `go to sleep', by drooping or closing up, to avoid frost damage. In the same year a final, iconic photograph was taken of him, with Emma playing the piano. His last work was on earthworms, before he died in 1882.
Thanks to Jane for bringing some of this lesser known work of Darwin to our attention. She may not have mentioned that as well as being a scientist herself, she is also a volunteer gardener at Down House, helping to recreate his garden .
Dick Alder