established； I shall have done good service； as an astonishing number of isolated facts can be thus connected together and rendered intelligible。〃
1869：
Publication of the fifth edition of the 〃Origin〃。
1871：
Publication of 〃The Descent of Man〃。
〃Although in the 'Origin of Species' the derivation of any particular species is never discussed； yet I thought it best； in order that no honourable man should accuse me of concealing my views； to add that by the work 'light would be thrown on the origin of man and his history'。〃
1872：
Publication of the sixth edition of the 〃Origin〃。
Publication of 〃The Expression of the Emotions in Man and Animals〃。
1874：
Publication of the second edition of 〃The Descent of Man〃。
〃The new edition of the 〃Descent〃 has turned out an awful job。 It took me ten days merely to glance over letters and reviews with criticisms and new facts。 It is a devil of a job。〃
Publication of the second edition of 〃The Structure and Distribution of Coral Reefs〃。
1875：
Publication of 〃Insectivorous Plants〃。
〃I begin to think that every one who publishes a book is a fool。〃
Publication of the second edition of 〃Variation in Animals and Plants〃。
Publication of 〃The Movements and Habits of Climbing Plants〃 as a separate book。
1876：
Wrote Autobiographical Sketch （〃Life and Letters〃； Vol。 I。； Chap II。）。
Publication of 〃The Effects of Cross and Self fertilisation〃。
〃I now （1881） believe； however；。。。that I ought to have insisted more strongly than I did on the many adaptations for self…fertilisation。〃
Publication of the second edition of 〃Observations on Volcanic Islands〃。
1877：
Publication of 〃The Different Forms of Flowers on Plants of the same species〃。
〃I do not suppose that I shall publish any more books。。。I cannot endure being idle； but heaven knows whether I am capable of any more good work。〃
Publication of the second edition of the Orchid book。
1878：
Publication of the second edition of 〃The Effects of Cross and Self fertilisation〃。
1879：
Publication of an English translation of Ernst Krause's 〃Erasmus Darwin〃； with a notice by Charles Darwin。 〃I am EXTREMELY glad that you approve of the little 'Life' of our Grandfather； for I have been repenting that I ever undertook it； as the work was quite beyond my tether。〃 （To Mr Francis Galton； Nov。 14； 1879。）
1880：
Publication of 〃The Power of Movement in Plants〃。
〃It has always pleased me to exalt plants in the scale of organised beings。〃
Publication of the second edition of 〃The Different Forms of Flowers〃。
1881：
Wrote a continuation of the Autobiography。
Publication of 〃The Formation of Vegetable Mould； through the Action of Worms〃。
〃It is the completion of a short paper read before the Geological Society more than forty years ago； and has revived old geological thoughts。。。As far as I can judge it will be a curious little book。〃
1882：
Charles Darwin died at Down； April 19； and was buried in Westminster Abbey； April 26； in the north aisle of the Nave a few feet from the grave of Sir Isaac Newton。
〃As for myself； I believe that I have acted rightly in steadily following and devoting my life to Science。 I feel no remorse from having committed any great sin； but have often and often regretted that I have not done more direct good to my fellow creatures。〃
The quotations in the above Epitome are taken from the Autobiography and published Letters：
〃The Life and Letters of Charles Darwin〃； including an Autobiographical Chapter。 Edited by his son； Francis Darwin； 3 Vols。； London； 1887。
〃Charles Darwin〃： His life told in an Autobiographical Chapter； and in a selected series of his published Letters。 Edited by his son； Francis Darwin； London； 1902。
〃More Letters of Charles Darwin〃。 A record of his work in a series of hitherto unpublished Letters。 Edited by Francis Darwin and A。C。 Seward； 2 Vols。； London； 1903。
I。 INTRODUCTORY LETTER
FROM SIR JOSEPH DALTON HOOKER；
O。M。； G。C。S。I。； C。B。； M。D。； D。C。L。； LL。D。； F。R。S。； ETC。
The Camp；
near Sunningdale；
January 15； 1909。
Dear Professor Seward；
The publication of a Series of Essays in Commemoration of the century of the birth of Charles Darwin and of the fiftieth anniversary of the publication of 〃The Origin of Species〃 is assuredly welcome and is a subject of congratulation to all students of Science。
These Essays on the progress of Science and Philosophy as affected by Darwin's labours have been written by men known for their ability to discuss the problems which he so successfully worked to solve。 They cannot but prove to be of enduring value； whether for the information of the general reader or as guides to investigators occupied with problems similar to those which engaged the attention of Darwin。
The essayists have been fortunate in having for reference the five published volumes of Charles Darwin's Life and Correspondence。 For there is set forth in his own words the inception in his mind of the problems； geological； zoological and botanical； hypothetical and theoretical； which he set himself to solve and the steps by which he proceeded to investigate them with the view of correlating the phenomena of life with the evolution of living things。 In his letters he expressed himself in language so lucid and so little burthened with technical terms that they may be regarded as models for those who were asked to address themselves primarily to the educated reader rather than to the expert。
I may add that by no one can the perusal of the Essays be more vividly appreciated than by the writer of these lines。 It was my privilege for forty years to possess the intimate friendship of Charles Darwin and to be his companion during many of his working hours in Study； Laboratory； and Garden。 I was the recipient of letters from him； relating mainly to the progress of his researches； the copies of which （the originals are now in the possession of his family） cover upwards of a thousand pages of foolscap； each page containing； on an average； three hundred words。
That the editorship of these Essays has been entrusted to a Cambridge Professor of Botany must be gratifying to all concerned in their production and in their perusal； recalling as it does the fact that Charles Darwin's instructor in scientific methods was his lifelong friend the late Rev。 J。S。 Henslow at that time Professor of Botany in the University。 It was owing to his recommendation that his pupil was appointed Naturalist to H。M。S。 〃Beagle〃； a service which Darwin himself regarded as marking the dawn of his scientific career。
Very sincerely yours；
J。D。 HOOKER。
II。 DARWIN'S PREDECESSORS。
By J。 ARTHUR THOMSON。 Professor of Natural History in the University of Aberdeen。
In seeking to discover Darwin's relation to his predecessors it is useful to distinguish the various services which he rendered to the theory of organic evolution。
（I） As everyone knows； the general idea of the Doctrine of Descent is that the plants and animals of the present…day are the lineal descendants of ancestors on the whole somewhat simpler； that these again are descended from yet simpler forms； and so on backwards towards the literal 〃Protozoa〃 and 〃Protophyta〃 about which we unfortunately know nothing。 Now no one supposes that Darwin originated this idea； which in rudiment at least is as old as Aristotle。 What Darwin did was to make it current intellectual coin。 He gave it a form that commended itself to the scientific and public intelligence of the day； and he won wide…spread conviction by showing with consummate skill that it was an effective formula to work with； a key which no lock refused。 In a scholarly； critical； and pre…eminently fair…minded way； admitting difficulties and removing them； foreseeing objections and forestalling them； he showed that the doctrine of descent supplied a modal interpretation of how our present…day fauna and flora have come to be。
（II） In the second place； Darwin applied the evolution…idea to particular problems； such as the descent of man； and showed what a powerful organon it is； introducing order into masses of uncorrelated facts； interpreting enigmas both of structure and function； both bodily and mental； and； best of all； stimulating and guiding further investigation。 But here again it cannot be claimed that Darwin was original。 The problem of the descent or ascent of man； and other particular cases of evolution； had attracted not a few naturalists before Darwin's day； though no one （except Herbert Spencer in the psychological domain （1855）） had come near him in precision and thoroughness of inquiry。
（III） In the third place； Darwin contributed largely to a knowledge of the factors in the evolution…process； especially by his analysis of what occurs in the case of domestic animals and cultivated plants； and by his elaboration of the theory of Natural Selection； which Alfred Russel Wallace independently stated at the same time； and of which there had been a few previous suggestions of a more or less vague description。 It was here that Darwin's originality was greatest； for he revealed to naturalists the many different formsoften very subtlewhich natural selection takes； and with the insight of a disciplined scientific imagination he realised what a mighty engine of progress it has been and is。
（IV） As an epoch…marking contribution； not only to Aetiology but to Natural History in the widest sense； we rank the picture which Darwin gave to the world of the web of life； that is to say； of the inter…relations and linkages in Nature。 For the Biology of the individualif that be not a contradiction in termsno idea is more fundamental than that of the correlation of organs； but Darwin's most characteristic contribution was not less fundamental；it was the idea of the correlation of organisms。 This； again； was not novel； we find it in the works of naturalist like Christian Conrad Sprengel； Gilbert White； and Alexander von Humboldt； but the realisation of its full import was distinctively Darwinian。
AS REGARDS THE GENERAL IDEA OF ORGANIC EVOLUTION。
While it is true； as Prof。 H。F。 Osborn puts it； that 〃'Before and after Darwin' will always be the ante et post urbem conditam of bio