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First published in 1846, Darwin's Geological Observations made up the third part of his memoir of his voyage on the Beagle during the years 1832–1836. While the first part (1842) focused on the structure and distribution of coral reefs and the second (1844) described the volcanic islands visited during the voyage, this third instalment is devoted exclusively to South America, where Darwin spent the longest period of the expedition. It discusses South America's geological and seismic history, the mineral content of lava and granite, and the deformation of metamorphic rock. Separate chapters cover different geographical areas, and topics include the formation of the East and West Coasts and the pampas, the plains and valleys of Chile, and the structure of the Cordillera. Geological Observations also includes detailed maps of South America and sketches of the terrain.

This volume includes many letters not previously published, and chronicles a year that was enlivened by scientific controversy and filled with scientific queries and discussions relating to Darwin's transmutation theory. His love of botany and his expanding experimental programme is well depicted by correspondence with professional botanists, horticulturalists, and hobbyists. Nine appendixes complement the letters by providing additional information from the Darwin Archive and from nineteenth-century publications. The letters also provide glimpses of life among the Victorian gentry, and reveal the practical and emotional support Darwin received from his family. Awarded the Founder's Medal of the Society of the History of Natural History, and the Modern Language Association of America's first Morton N. Cohen Award for a distinguished edition of letters.

This volume is part of the definitive edition of letters written by and to Charles Darwin, the most celebrated naturalist of the nineteenth century. Notes and appendixes put these fascinating and wide-ranging letters in context, making the letters accessible to both scholars and general readers. Darwin depended on correspondence to collect data from all over the world and to discuss his emerging ideas with scientific colleagues, many of whom he never met in person. The letters are published chronologically: volume 20 includes letters from 1872, the year in which The Expression of the Emotions in Man and Animals was published, making ground-breaking use of photography. Also in this year, the sixth and final edition of On the Origin of Species was published and Darwin resumed his work on carnivorous plants and plant movement, finding unexpected similarities between the plant and animal kingdoms.

This is the second volume of the complete edition of The Correspondence of Charles Darwin. For the first time full authoritative texts of Darwin's letters are available, edited according to modern textual editorial principles and practice. The letters in this volume were written during the seven years following Darwin's return to England from the Beagle voyage. It was a period of extraordinary activity and productivity in which he became recognised as a naturalist of outstanding ability, as an author and editor, and as a professional man with official responsibilities in several scientific organisations. During these years he published two books and fifteen papers and also organised and superintended the publication of the Zoology of the Voyage of HMS Beagle, for which he described the locations of the fossils and the habitats and behaviour of the living species he had collected. Busy as he was with scientific activities, Darwin found time to re-establish family ties and friendships, a

The Correspondence of Charles Darwin provides, for the first time, the full, authoritative texts of all known and available letters to and from Charles Darwin, the originator of the theory of evolution by natural selection. The letters are accompanied by detailed explanatory footnotes and relevant supplementary materials, and offer unparalleled insight into Darwin's experiments, thoughts, friendships, and family life. Volume 12 of this continuing series contains letters for 1864, when Darwin, despite continuing illness, was carrying out botanical experiments and working on his book, The Variation of Plants and Animals under Domestication. The volume also sheds light on the worldwide reception of Darwin's theory, with letters from correspondents in the United States and Germany, and also on the continuing controversy in Britain, especially with the award of the Royal Society's prestigious Copley Medal to Darwin at the end of the year.

This volume is part of the definitive edition of letters written by and to Charles Darwin, the most celebrated naturalist of the nineteenth century. Notes and appendixes put these fascinating and wide-ranging letters in context, making the letters accessible to both scholars and general readers. Darwin depended on correspondence to collect data from all over the world, and to discuss his emerging ideas with scientific colleagues, many of whom he never met in person. The letters are published chronologically: volume 25 includes letters from 1877, the year in which Darwin published Forms of Flowers and with his son Francis carried out experiments on plant movement and bloom on plants. Darwin was awarded an honorary LL.D. by Cambridge University, and appeared in person to receive it. The volume contains a number of appendixes, including two on the albums of photograph sent to Darwin by his Dutch, German, and Austrian admirers.

This volume is part of the definitive edition of letters written by and to Charles Darwin, the most celebrated naturalist of the nineteenth century. Notes and appendixes put these fascinating and wide-ranging letters in context, making the letters accessible to both scholars and general readers. Darwin depended on correspondence to collect data from all over the world, and to discuss his emerging ideas with scientific colleagues, many of whom he never met in person. The letters are published chronologically: Volume 21 includes letters from 1873, the year in which Darwin received responses to his work on human and animal expression. Also in this year, Darwin continued his work on carnivorous plants and plant movement, finding unexpected similarities between the plant and animal kingdoms, raised a subscription for his friend Thomas Henry Huxley, and decided to employ a scientific secretary for the first time - his son Francis.

The Correspondence of Charles Darwin provides, for the first time, full, authoritative texts of all known and available letters to and from Charles Darwin. The letters are accompanied by detailed explanatory footnotes and supplementary materials, and offer unparalleled insight into Darwin's experiments, thoughts, friendships, and family life. Volume 13 of this continuing series contains letters for 1865, when Darwin published his long paper on climbing plants and continued working on his book, The Variation of Plants and Animals under Domestication. In this year, Robert FitzRoy, former captain of HMS Beagle, committed suicide; Darwin's great friend Joseph Dalton Hooker became director of the Royal Botanic Gardens, Kew; and Charles Lyell and John Lubbock quarrelled over an alleged incident of plagiarism. The volume also contains a supplement of over 100 letters discovered or redated since the series began publication, including a fascinating collection of letters written when Darwin was

This volume is part of the definitive edition of letters written by and to Charles Darwin, the most celebrated naturalist of the nineteenth century. Notes and appendixes put these fascinating and wide-ranging letters in context, making the letters accessible to both scholars and general readers. Darwin depended on correspondence to collect data from all over the world and to discuss his emerging ideas with scientific colleagues, many of whom he never met in person. The letters are published chronologically: volume 22 includes letters from 1874, the year in which Darwin completed his research on insectivorous plants and published second editions of Descent of Man and Coral Reefs. The year also saw an acrimonious dispute between Darwin and St George Jackson Mivart as a result of an anonymous review the latter had written in which he criticised Darwin's son George.

This volume is part of the definitive edition of letters written by and to Charles Darwin, the most celebrated naturalist of the nineteenth century. Notes and appendixes put these fascinating and wide-ranging letters in context, making the letters accessible to both scholars and general readers. Darwin depended on correspondence to collect data from all over the world, and to discuss his emerging ideas with scientific colleagues, many of whom he never met in person. The letters are published chronologically: volume 26 includes letters from 1878, the year in which Darwin with his son Francis carried out experiments on plant movement and bloom on plants. Francis spent the summer at a botanical research institute in Germany; and father and son exchanged many detailed letters about his work. Meanwhile, Darwin tried to secure government support for attempts by one of his Irish correspondents to breed a blight-resistant potato.

This volume is part of the definitive edition of letters written by and to Charles Darwin, the most celebrated naturalist of the nineteenth century. Notes and appendixes put these fascinating and wide-ranging letters in context, making the letters accessible to both scholars and general readers. Darwin depended on correspondence to collect data from all over the world, and to discuss his emerging ideas with scientific colleagues, many of whom he never met in person. The letters are published chronologically: Volume 23 includes letters from 1875, the year in which Darwin wrote and published Insectivorous plants, a botanical work that was a great success with the reading public, and started writing Cross and self fertilisation in the vegetable kingdom. The volume contains an appendix on the 1875 anti-vivisection debates, with which Darwin was closely involved, giving evidence before a Royal Commission on the subject.

This book, published in 1881, was the result of many years of experimentation and observation by Darwin in the open-air laboratory of his garden at Down House in Kent. As he wrote in his introduction, the subject of soil disturbance by worms 'may appear an insignificant one, but we shall see that it possesses some interest'. He goes on to demonstrate the immensity – in size and over time – of the accumulated tiny movements of soil by earthworms, and their vital role in aerating the soil and breaking down vegetable material to keep the topsoil, the growing medium for all plant life and thus vital to human existence, fertile and healthy. At a time when there is huge interest in growing food organically and without using artificial fertilisers, Darwin's insights are as important, and his descriptions of his experiments as fascinating, as they were in the late nineteenth century.

This volume covers the culmination of Darwin's work on species. From early in 1856, when he was persuaded that the time had come to publish an account of his heterodox theories, through 1857, Darwin's letters document the labour involved in composing his 'big species book', his zest for research, and his unflagging determination to succeed. As always, old friends and more recent acquaintances were drawn into the project. Darwin writes for the first time to Alfred Russel Wallace seeking specimens of Malayan fowls. Joseph Dalton Hooker is his sounding-board for botanical speculations and Thomas Henry Huxley soon takes up a similar role in matters of comparative anatomy and embryology. William Bernhard Tegetmeier is the provider of pigeons and poultry and Asa Gray dispatches from Massachusetts invaluable botanical data. Darwin fully exploits his gift for drawing the best from his correspondents and, collectively, their letters provide a remarkable survey of what was - and was not - believ

This volume is part of the definitive edition of letters written by and to Charles Darwin, the most celebrated naturalist of the nineteenth century. It is already an important source for students and scholars in many academic disciplines. Notes and appendixes put these fascinating and wide-ranging letters in context, making the letters accessible to both scholars and general readers. Darwin depended on correspondence to collect data from all over the world, and to discuss his emerging ideas with scientific colleagues, many of whom he never met in person. The letters are published chronologically: Volume 18 includes letters from 1870, as well as a supplement of more than a hundred recently discovered or redated letters from before 1870. During 1870 Darwin was making final preparations for publication of Descent of Man, as well as continuing his research on expression in humans and animals.

This is the fourth volume of the complete edition of The Correspondence of Charles Darwin. For the first time full authoritative texts of Darwin's letters are available, edited according to modern textual editorial principles and practice. This volume covers the first years of Darwin's study of the structure and systematics of barnacles: work that involved a worldwide search for specimens, detailed microscopic investigations, a consideration of the theoretical assumptions underlying classification schemes, and the solution of practical problems of zoological nomenclature. Darwin's convictions about the nature and origin of species influenced his observations and conclusions and provided insights that led to some remarkable discoveries. Throughout this period Darwin also maintained his involvement in major geological debates, as shown by important exchanges with Charles Lyell, Robert Chambers, James Dwight Dana, Bernhard Studer, and others. The letters to Darwin include Joseph Dalton Ho

Darwin had long been fascinated by insectivorous plants, from the native British sundews and bladderworts to the exotic pinguiculas and nepenthes which he encountered during the Beagle voyage. Growing in environments low in soil nutrients, their highly specialised ways of obtaining enough food, including the capability for fast movement in the case of the Venus flytrap, were evidence of evolutionary adaptation. But he was also interested in what food they needed, and whether they would be selective when offered a varied diet; and how did the flytrap close its trap on its prey? Darwin conducted a range of simple but ingenious experiments on his collection of insectivores and observed and noted the results of each with his customary meticulousness. The results can be seen in this book, which remains of enormous interest to anyone whose imagination has been fired by these strange and beautiful plants.

During 1867 Darwin intensified lines of research that were to result in two important publications, Descent of Man and Selection in Relation to Sex and Expression of the Emotions in Man and Animals. Darwin circulated a questionnaire on human expression, asking his established contacts to pass it on to their acquaintances, with the result that he began to receive letters from an even more diverse and far-flung network of correspondents than had previously been the case. Convinced that human descent was strongly influenced by sexual selection, he also started to ask his correspondents about sexual differences in animals and birds. At the same time, he was working on the proof-sheets of another major work, Variation of Animals and Plants under Domestication, while negotiating almost weekly with French, German, and Russian translators. For information on the Charles Darwin Correspondence Project, see http://www.lib.cam.ac.uk/Departments/Darwin.

This is the third volume of the complete edition of The Correspondence of Charles Darwin. For the first time full authoritative texts of Darwin's letters are available, edited according to modern textual editorial principles and practice. The letters in this volume were written during the years 1844–6. By 1844 Darwin had become an established figure within the circle of London naturalists and his life at Down had assumed the regularity that the responsibility for a thriving and growing household entailed. Despite his move to rural Kent, Darwin was not isolated, and this volume shows how frequent were his trips to London and further afield, how regular his meetings with his scientific colleagues, and how extensive his network of correspondents.

This volume is part of the definitive edition of letters written by and to Charles Darwin, the most celebrated naturalist of the nineteenth century. Notes and appendixes put these fascinating and wide-ranging letters in context, making the letters accessible to both scholars and general readers. Darwin depended on correspondence to collect data from all over the world, and to discuss his emerging ideas with scientific colleagues, many of whom he never met in person. The letters are published chronologically: volume 24 includes letters from 1876, the year in which Darwin published Cross and Self Fertilisation in the Vegetable Kingdom, and started writing Forms of Flowers. In 1876, Darwin's daughter-in-law, Amy, died shortly after giving birth to a son, Bernard Darwin, an event that devastated the family. The volume includes a supplement of 182 letters from earlier years, including a newly discovered collection of letters from William Darwin, Darwin's eldest son.

This volume inaugurates a complete edition of The Correspondence of Charles Darwin. For the first time full authoritative texts of Darwin's letters are available, edited according to modern textual editorial principles and practice. The first volume of the edition contains the letters of the years 1821–1836. They begin with one written to Darwin at the age of twelve and continue through his school days at Shrewsbury, his two years as a medical student at Edinburgh, the undergraduate years at Cambridge, and his five years of exploration and learning during the voyage of the Beagle. These were Darwin's years of initiation and preparation for a life of science. In the earliest letters Darwin appears already keenly interested in natural history and an avid collector of minerals, plants, marine invertebrates, and insects - especially beetles. The letters of the succeeding years tell the story of the young Darwin's development up to his return to England when, at the age of twenty-seven, he

Charles Darwin's On the Origin of Species By Means of Natural Selection is both a key scientific work of research, still read by scientists, and a readable narrative that has had a cultural impact unmatched by any other scientific text. First published in 1859, it has continued to sell, to be reviewed and discussed, attacked and defended. The Origin is one of those books whose controversial reputation ensures that many who have never read it nevertheless have an opinion about it. Jim Endersby's major scholarly edition debunks some of the myths that surround Darwin's book, while providing a detailed examination of the contexts within which it was originally written, published and read. Endersby provides a very readable introduction to this classic text and a level of scholarly apparatus (explanatory notes, bibliography and appendixes) that is unmatched by any other edition.

Charles Darwin's On the Origin of Species By Means of Natural Selection is both a key scientific work of research, still read by scientists, and a readable narrative that has had a cultural impact unmatched by any other scientific text. First published in 1859, it has continued to sell, to be reviewed and discussed, attacked and defended. The Origin is one of those books whose controversial reputation ensures that many who have never read it nevertheless have an opinion about it. Jim Endersby's major scholarly edition debunks some of the myths that surround Darwin's book, while providing a detailed examination of the contexts within which it was originally written, published and read. Endersby provides a very readable introduction to this classic text and a level of scholarly apparatus (explanatory notes, bibliography and appendixes) that is unmatched by any other edition.

Charles Darwin depended on correspondence to collect data from all over the world, and to discuss his emerging ideas with scientific colleagues, many of whom he never met in person. In January of 1868, Darwin's Variation Under Domestication was published. The first printing of 1500 copies rapidly sold out and the publisher, John Murray, ordered a second printing. Responses to this new book, added to Darwin's continuing research into sexual selection and the expression of the emotions, increased the quantity of Darwin's correspondence to such an extent that the letters from 1868 fill two volumes. The letters he wrote and received during this year are presented here in chronological order across two volumes, with notes and appendices to put them into context, explain references, and provide information on related works. For information on the Charles Darwin Correspondence Project, see http://www.darwinproject.ac.uk.

The correspondence in this volume is dominated by the public and private response to the publication of Darwin's Origin of Species. Volume 8 opens with Darwin eagerly scrutinising each new review, as one by one all the major organs of the day carried notices of the book. To those who express their views privately in letters, Darwin responds patiently and thoughtfully, answering their objections and attempting to guide their fuller understanding of the operation of natural selection. His more personal thoughts emerge in letters to his friends Joseph Dalton Hooker, Charles Lyell, and Thomas Henry Huxley. This volume presents a wealth of detailed information, giving the full range of response to the Origin and revealing how the Victorians coped with a theory that many well recognised would revolutionise thinking about the organic world and human ancestry.

This volume is part of the definitive edition of letters written by and to Charles Darwin, the most celebrated naturalist of the nineteenth century. Notes and appendixes put these fascinating and wide-ranging letters in context, making the letters accessible to both scholars and general readers. Darwin depended on correspondence to collect data from all over the world, and to discuss his emerging ideas with scientific colleagues, many of whom he never met in person. The letters are published chronologically. In 1880, Darwin published On The Power of Movement in Plants, and began writing his final book, The Formation of Vegetable Mould through the Action of Worms. He was engaged in controversy with Samuel Butler, following publication of his last book, Erasmus Darwin. At the end of the year, he succeeded in raising support for a Civil List pension for Alfred Russel Wallace, co-discoverer of the theory of natural selection.

Written in collaboration with his son Francis, a notable botanist, this 1880 book builds on Darwin's earlier investigations into climbing plants, orchids, insectivorous plants, flower variety, and the processes of fertilisation. This detailed study of many species from seed to mature plant further develops Darwin's work on adaptation and evolution, with the aim of collating the results of individual studies into common factors applicable to plants in general. Particular emphasis is given to analysis and investigation of the process here termed circumnutation, the movement of the stem of the plant in order to direct the head in certain directions. This is seen as of paramount importance, with the conclusion that it is modification of this feature that has enabled plants to adapt and evolve so diversely. The authors also note similarities between plants and animals, such as sensitivity to touch and habit of action at certain times.

The correspondence in this volume reveals Darwin carefully monitoring the response to The Origin of Species. Early in 1861 he completed the preparation of a third and much-revised edition, using the opportunity to answer his critics. As these letters make clear, Darwin understood the importance of support from younger scientists for the future of his theory. Darwin's long-time supporters - including Asa Gray, Charles Lyell and Joseph Dalton Hooker - also feature largely in his correspondence. Escaping the confines of collating and writing up his work on variation in domesticated animals and plants, Darwin plunged into detailed studies of insectivorous plants and orchid pollination. On a more personal side, the correspondence details Darwin in the role of solicitous father ensuring a secure future for his son William. The letters in Volume 9 provide another indispensable collection for those interested in Darwin's life, work and world.

This volume is part of the definitive edition of letters written by and to Charles Darwin, the most celebrated naturalist of the nineteenth century. Notes and appendixes put these fascinating and wide-ranging letters in context, making the letters accessible to both scholars and general readers. Darwin depended on correspondence to collect data from all over the world, and to discuss his emerging ideas with scientific colleagues, many of whom he never met in person. The letters are published chronologically: volume 27 includes letters from 1879, the year in which Darwin completed his manuscript on movement in plants. He also researched and published a biography of his grandfather Erasmus. The Darwins spent most of August on holiday in the Lake District. In October, Darwin's youngest son, Horace, became officially engaged to Ida Farrer, after some initial resistance from her father, who, although an admirer of Charles Darwin, thought Horace a poor prospect for his daughter.

The letters in this volume cover two of the most momentous years in Darwin's life. Begun in 1856 and the fruit of twenty years of study and reflection, Darwin's manuscript on the species question was a little more than half finished, and at least two years from publication, when in June 1858 Darwin unexpectedly received a letter and a manuscript from Alfred Russel Wallace indicating that he too had independently formulated a theory of natural selection. The letters detail the various stages in the preparation of what was to become one of the world's most famous works: Darwin's On the Origin of Species by Means of Natural Selection, published by John Murray in November 1859. They reveal the first impressions of Darwin's book given by his most trusted confidants, and they relate Darwin's anxious response to the early reception of his theory by friends, family members, and prominent naturalists. This volume provides the capstone to Darwin's remarkable efforts for more than two decades to

Charles Darwin's health improved substantially in 1866 under a dietary and exercise regime prescribed by his physician Henry Bence Jones. With renewed vigour, he worked steadily on his manuscript of Variation of Plants and Animals under Domestication, submitting all but the final chapter to his publisher in December. He also worked on the fourth, and much revised, edition of Origin which was delivered to printers in July, and preparations were begun for a third German edition of Origin. His improved health allowed him a more active social life. At Down, Darwin entertained a number of scientific colleagues whom he had known previously only through correspondence. He also made his first appearance in London scientific society in many years, touring the Zoological Gardens at Regent's Park, and appearing at a soirée at the Royal Society.

Throughout history, some books have changed the world. They have transformed the way we see ourselves—and each other. They have inspired debate, dissent, war and revolution. They have enlightened, out

Throughout history, some books have changed the world. They have transformed the way we see ourselves - and each other. They have inspired debate, dissent, war and revolution. They have enlightened, o

′How fleeting are the wishes and efforts of man! how short his time! and consequently how poor will his products be, compared with those accumulated by nature during whole geological periods.′Still co

This pivotal volume in the definitive edition of Charles Darwin's letters covers the year 1871, the year in which Descent of Man, Darwin's first public statement on human evolution, was published. The large number of letters in this year - more than 800 - reflects the excitement this caused. Darwin depended on correspondence to collect data from a growing network of contacts all over the world and to discuss his emerging ideas with colleagues, many of whom he never met in person. This year also saw the marriage of Darwin's daughter Henrietta, the first of his children to marry; the volume includes her personal journal of the year, published here for the first time, which complements letters that hint at her important role in her father's work as both commentator and editor. Notes and appendixes put these fascinating and wide-ranging letters in context, making them accessible to both scholars and general readers.

The correspondence in this volume reveals the two sides of Darwin's life in a new intensity. It opens with a family tragedy in the death of Darwin's oldest and best loved daughter, Anne, and goes on to show how Darwin sought relief from his loss through work, with a single-minded but increasingly weary commitment to the completion of his cirripede monographs. In September 1854, as soon as the final proofs of the last barnacle volume had been returned to the printer, Darwin threw himself into a resumption of his species work. He followed up old ideas by initiating new experiments and establishing a worldwide correspondence that encompassed geographical distribution, variation, and plant and animal breeding. The wealth of letters through 1855 makes evident the frenzy of intellectual activity that followed Darwin's terse announcement in his diary: 'Sept. 9th (1854) began sorting notes for Species Theory …'

On 27th December 1831, HMS Beagle set out from Plymouth under the command of Captain Robert Fitzroy on a voyage that lasted nearly 5 years. The purpose of the trip was to complete a survey of the southern coasts of South America, and afterwards to circumnavigate the globe. The ship's geologist and naturalist was Charles Darwin. Darwin kept a diary throughout the voyage in which he recorded his daily activities, not only on board the ship but also during the several long journeys that he made on horseback in Patagonia and Chile. His entries tell the story of one of the most important scientific journeys ever made with matchless immediacy and vivid descriptiveness.

Charles Darwin's On the Origin of Species is unquestionably one of the chief landmarks in biology. The Origin (as it is widely known) was literally only an abstract of the manuscript Darwin had originally intended to complete and publish as the formal presentation of his views on evolution. Compared with the Origin, his original long manuscript work on Natural Selection, which is presented here and made available for the first time in printed form, has more abundant examples and illustrations of Darwin's argument, plus an extensive citation of sources.

This sixth edition of The Origin of Species was published in 1876. It is the last edition on which Darwin himself worked before his death in 1882, and offers a useful complement to the 2009 scholarly edition, edited by Jim Endersby and published by Cambridge University Press in Darwin's bicentennial year. The sixth edition contains a 'historical sketch' in which Darwin reviews the many works by eminent European and American scientists – beginning with Lamarck in 1801 – in which ideas of evolutionary species change and of natural selection were touched on but not developed. This edition, like all from the second onwards, contains the words 'by the Creator', controversially added to the famous last sentence in the book: 'There is grandeur in this view of life, with its several powers, having been breathed by the Creator into a few forms or into one...'

'I have always maintained that, excepting fools, men did not differ much in intellect, only in zeal & hard work; and I still think there is an eminently important difference'. Throughout 1869, Darwin continued to collect data for his two most significant books after Origin: The Descent of Man and Expression of the Emotions. Explorers, diplomats, and missionaries all over the world were politely encouraged to investigate, for example, how emotions such as surprise, anger and shame were expressed in different cultures. As Darwin's research on human evolution neared completion, he learned that Alfred Russel Wallace, the co-discoverer of the theory, had begun to raise questions about its application to certain aspects of human development, attributing these to the action of a 'higher power'. In his correspondence, Wallace alluded to his belief in spiritualism, which he fully believed to be open to scientific investigation, but which gave Darwin much pause.

As the sheer volume of his correspondence indicates, 1862 was a very 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 he carried out. The promotion of his theory of natural selection also continued: Darwin's own work on it expanded, Thomas Henry Huxley gave lectures about it, and Henry Walter Bates invoked it to explain mimicry in butterflies. As well as monitoring the progress of his scientific work, the correspondence also records the continuing effects of Darwin's ill-health. Serious illness in two of his children also disrupts his work.