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+Project Gutenberg Etext Darwin and Modern Science, by A C Seward
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+Darwin and Modern Science
+
+by A.C. Seward
+
+September, 1999  [Etext #1909]
+
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+Project Gutenberg Etext Darwin and Modern Science, by A C Seward
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+
+DARWIN AND MODERN SCIENCE
+
+ESSAYS IN COMMEMORATION OF THE CENTENARY OF THE BIRTH OF CHARLES DARWIN AND
+OF THE FIFTIETH ANNIVERSARY OF THE PUBLICATION OF "THE ORIGIN OF SPECIES"
+
+
+BY
+
+A.C. SEWARD
+
+
+
+
+"My success as a man of science, whatever this may have amounted to, has
+been determined, as far as I can judge, by complex and diversified mental
+qualities and conditions.  Of these, the most important have been--the love
+of science--unbounded patience in long reflecting over any subject--
+industry in observing and collecting facts--and a fair share of invention
+as well as of common sense.  With such moderate abilities as I possess, it
+is truly surprising that I should have influenced to a considerable extent
+the belief of scientific men on some important points."
+
+Autobiography (1881); "The Life and Letters of Charles Darwin", Vol. 1.
+page 107.
+
+
+PREFACE
+
+At the suggestion of the Cambridge Philosophical Society, the Syndics of
+the University Press decided in March, 1908, to arrange for the publication
+of a series of Essays in commemoration of the Centenary of the birth of
+Charles Darwin and of the Fiftieth anniversary of the publication of "The
+Origin of Species".  The preliminary arrangements were made by a committee
+consisting of the following representatives of the Council of the
+Philosophical Society and of the Press Syndicate:  Dr H.K. Anderson, Prof.
+Bateson, Mr Francis Darwin, Dr Hobson, Dr Marr, Prof. Sedgwick, Mr David
+Sharp, Mr Shipley, Prof. Sorley, Prof. Seward.  In the course of the
+preparation of the volume, the original scheme and list of authors have
+been modified:  a few of those invited to contribute essays were, for
+various reasons, unable to do so, and some alterations have been made in
+the titles of articles.  For the selection of authors and for the choice of
+subjects, the committee are mainly responsible, but for such share of the
+work in the preparation of the volume as usually falls to the lot of an
+editor I accept full responsibility.
+
+Authors were asked to address themselves primarily to the educated layman
+rather than to the expert.  It was hoped that the publication of the essays
+would serve the double purpose of illustrating the far-reaching influence
+of Darwin's work on the progress of knowledge and the present attitude of
+original investigators and thinkers towards the views embodied in Darwin's
+works.
+
+In regard to the interpretation of a passage in "The Origin of Species"
+quoted by Hugo de Vries, it seemed advisable to add an editorial footnote;
+but, with this exception, I have not felt it necessary to record any
+opinion on views stated in the essays.
+
+In reading the essays in proof I have availed myself freely of the willing
+assistance of several Cambridge friends, among whom I wish more especially
+to thank Mr Francis Darwin for the active interest he has taken in the
+preparation of the volume.  Mrs J.A. Thomson kindly undertook the
+translation of the essays by Prof. Weismann and Prof. Schwalbe; Mrs James
+Ward was good enough to assist me by translating Prof. Bougle's article on
+Sociology, and to Mr McCabe I am indebted for the translation of the essay
+by Prof. Haeckel.  For the translation of the botanical articles by Prof.
+Goebel, Prof. Klebs and Prof. Strasburger, I am responsible; in the
+revision of the translation of Prof. Strasburger's essay Madame Errera of
+Brussels rendered valuable help.  Mr Wright, the Secretary of the Press
+Syndicate, and Mr Waller, the Assistant Secretary, have cordially
+cooperated with me in my editorial work; nor can I omit to thank the
+readers of the University Press for keeping watchful eyes on my
+shortcomings in the correction of proofs.
+
+The two portraits of Darwin are reproduced by permission of Messrs Maull
+and Fox and Messrs Elliott and Fry.  The photogravure of the study at Down
+is reproduced from an etching by Mr Axel Haig, lent by Mr Francis Darwin;
+the coloured plate illustrating Prof. Weismann's essay was originally
+published by him in his "Vortrage uber Descendenztheorie" which afterwards
+appeared (1904) in English under the title "The Evolution Theory".  Copies
+of this plate were supplied by Messrs Fischer of Jena.
+
+The Syndics of the University Press have agreed, in the event of this
+volume being a financial success, to hand over the profits to a University
+fund for the endowment of biological research.
+
+It is clearly impossible to express adequately in a single volume of Essays
+the influence of Darwin's contributions to knowledge on the subsequent
+progress of scientific inquiry.  As Huxley said in 1885:  "Whatever be the
+ultimate verdict of posterity upon this or that opinion which Mr Darwin has
+propounded; whatever adumbrations or anticipations of his doctrines may be
+found in the writings of his predecessors; the broad fact remains that,
+since the publication and by reason of the publication of "The Origin of
+Species" the fundamental conceptions and the aims of the students of living
+Nature have been completely changed...But the impulse thus given to
+scientific thought rapidly spread beyond the ordinarily recognised limits
+of Biology.  Psychology, Ethics, Cosmology were stirred to their
+foundations, and 'The Origin of Species' proved itself to be the fixed
+point which the general doctrine needed in order to move the world."
+
+In the contributions to this Memorial Volume, some of the authors have more
+especially concerned themselves with the results achieved by Darwin's own
+work, while others pass in review the progress of research on lines which,
+though unknown or but little followed in his day, are the direct outcome of
+his work.
+
+The divergence of views among biologists in regard to the origin of species
+and as to the most promising directions in which to seek for truth is
+illustrated by the different opinions of contributors.  Whether Darwin's
+views on the modus operandi of evolutionary forces receive further
+confirmation in the future, or whether they are materially modified, in no
+way affects the truth of the statement that, by employing his life "in
+adding a little to Natural Science," he revolutionised the world of
+thought.  Darwin wrote in 1872 to Alfred Russel Wallace:  "How grand is the
+onward rush of science:  it is enough to console us for the many errors
+which we have committed, and for our efforts being overlaid and forgotten
+in the mass of new facts and new views which are daily turning up."  In the
+onward rush, it is easy for students convinced of the correctness of their
+own views and equally convinced of the falsity of those of their fellow-
+workers to forget the lessons of Darwin's life.  In his autobiographical
+sketch, he tells us, "I have steadily endeavoured to keep my mind free so
+as to give up any hypothesis, however much beloved...as soon as facts are
+shown to be opposed to it."  Writing to Mr J. Scott, he says, "It is a
+golden rule, which I try to follow, to put every fact which is opposed to
+one's preconceived opinion in the strongest light.  Absolute accuracy is
+the hardest merit to attain, and the highest merit.  Any deviation is
+ruin."
+
+He acted strictly in accordance with his determination expressed in a
+letter to Lyell in 1844, "I shall keep out of controversy, and just give my
+own facts."  As was said of another son of Cambridge, Sir George Stokes,
+"He would no more have thought of disputing about priority, or the
+authorship of an idea, than of writing a report for a company promoter." 
+Darwin's life affords a striking confirmation of the truth of Hazlitt's
+aphorism, "Where the pursuit of truth has been the habitual study of any
+man's life, the love of truth will be his ruling passion."  Great as was
+the intellect of Darwin, his character, as Huxley wrote, was even nobler
+than his intellect.
+
+A.C. SEWARD.
+
+Botany School, Cambridge,
+March 20, 1909.
+
+
+CONTENTS
+
+I.  INTRODUCTORY LETTER TO THE EDITOR from SIR JOSEPH DALTON HOOKER, O.M.
+
+II.  DARWIN'S PREDECESSORS:
+  J. ARTHUR THOMSON, Professor of Natural History in the University of
+Aberdeen.
+
+III.  THE SELECTION THEORY:
+  AUGUST WEISMANN, Professor of Zoology in the University of Freiburg
+(Baden).
+
+IV.  VARIATION:
+  HUGO DE VRIES, Professor of Botany in the University of Amsterdam.
+
+V.  HEREDITY AND VARIATION IN MODERN LIGHTS:
+  W. BATESON, Professor of Biology in the University of Cambridge.
+
+VI.  THE MINUTE STRUCTURE OF CELLS IN RELATION TO HEREDITY:
+  EDUARD STRASBURGER, Professor of Botany in the University of Bonn.
+
+VII.  "THE DESCENT OF MAN":
+  G. SCHWALBE, Professor of Anatomy in the University of Strassburg.
+
+VIII.  CHARLES DARWIN AS AN ANTHROPOLOGIST:
+  ERNST HAECKEL, Professor of Zoology in the University of Jena.
+
+IX.  SOME PRIMITIVE THEORIES OF THE ORIGIN OF MAN:
+  J.G. FRAZER, Fellow of Trinity College, Cambridge.
+
+X.  THE INFLUENCE OF DARWIN ON THE STUDY OF ANIMAL EMBRYOLOGY:
+  A. SEDGWICK, Professor of Zoology and Comparative Anatomy in the
+University of Cambridge.
+
+XI.  THE PALAEONTOLOGICAL RECORD.  I. ANIMALS:
+  W.B. SCOTT, Professor of Geology in the University of Princeton.
+
+XII.  THE PALAEONTOLOGICAL RECORD.  II. PLANTS:
+  D.H. SCOTT, President of the Linnean Society of London.
+
+XIII.  THE INFLUENCE OF ENVIRONMENT ON THE FORMS OF PLANTS:
+  GEORG KLEBS, Professor of Botany in the University of Heidelberg.
+
+XIV.  EXPERIMENTAL STUDY OF THE INFLUENCE OF ENVIRONMENT ON ANIMALS:
+  JACQUES LOEB, Professor of Physiology in the University of California.
+
+XV.  THE VALUE OF COLOUR IN THE STRUGGLE FOR LIFE:
+  E.B. POULTON, Hope Professor of Zoology in the University of Oxford.
+
+XVI.  GEOGRAPHICAL DISTRIBUTION OF PLANTS:
+  SIR WILLIAM THISELTON-DYER.
+
+XVII.  GEOGRAPHICAL DISTRIBUTION OF ANIMALS:
+  HANS GADOW, Strickland Curator and Lecturer on Zoology in the University
+of Cambridge.
+
+XVIII.  DARWIN AND GEOLOGY:
+  J.W. JUDD.
+
+XIX.  DARWIN'S WORK ON THE MOVEMENTS OF PLANTS:
+  FRANCIS DARWIN.
+
+XX.  THE BIOLOGY OF FLOWERS:
+  K. GOEBEL, Professor of Botany in the University of Munich.
+
+XXI.  MENTAL FACTORS IN EVOLUTION:
+  C. LLOYD MORGAN, Professor of Psychology at University College, Bristol.
+
+XXII.  THE INFLUENCE OF THE CONCEPTION OF EVOLUTION ON MODERN PHILOSOPHY:
+  H. HOFFDING, Professor of Philosophy in the University of Copenhagen.
+
+XXIII.  DARWINISM AND SOCIOLOGY:
+  C. BOUGLE, Professor of Social Philosophy in the University of Toulouse,
+and Deputy-Professor at the Sorbonne, Paris.
+
+XXIV.  THE INFLUENCE OF DARWIN UPON RELIGIOUS THOUGHT:
+  REV. P.N. WAGGETT.
+
+XXV.  THE INFLUENCE OF DARWINISM ON THE STUDY OF RELIGIONS:
+  JANE ELLEN HARRISON, Staff-Lecturer and sometime Fellow of Newnham
+College, Cambridge.
+
+XXVI.  EVOLUTION AND THE SCIENCE OF LANGUAGE:
+  P. GILES, Reader in Comparative Philology in the University of Cambridge.
+
+XXVII.  DARWINISM AND HISTORY:
+  J.B. BURY, Regius Professor of Modern History in the University of
+Cambridge.
+
+XXVIII.  THE GENESIS OF DOUBLE STARS:
+  SIR GEORGE DARWIN, Plumian Professor of Astronomy and Experimental
+Philosophy in the University of Cambridge.
+
+XXIX.  THE EVOLUTION OF MATTER:
+  W.C.D. WHETHAM, Fellow of Trinity College, Cambridge.
+
+INDEX.
+
+
+DATES OF THE PUBLICATION Of CHARLES DARWIN'S BOOKS AND OF THE PRINCIPAL
+EVENTS IN HIS LIFE
+
+1809:
+
+Charles Darwin born at Shrewsbury, February 12.
+
+1817:
+
+"At 8 1/2 years old I went to Mr Case's school."  (A day-school at
+Shrewsbury kept by the Rev G. Case, Minister of the Unitarian Chapel.)
+
+1818:
+
+"I was at school at Shrewsbury under a great scholar, Dr Butler; I learnt
+absolutely nothing, except by amusing myself by reading and experimenting
+in Chemistry."
+
+1825:
+
+"As I was doing no good at school, my father wisely took me away at a
+rather earlier age than usual, and sent me (Oct. 1825) to Edinburgh
+University with my brother, where I stayed for two years."
+
+1828:
+
+Began residence at Christ's College, Cambridge.
+
+"I went to Cambridge early in the year 1828, and soon became acquainted
+with Professor Henslow...Nothing could be more simple, cordial and
+unpretending than the encouragement which he afforded to all young
+naturalists."
+
+"During the three years which I spent at Cambridge my time was wasted, as
+far as the academical studies were concerned, as completely as at Edinburgh
+and at school."
+
+"In order to pass the B.A. Examination, it was...necessary to get up
+Paley's 'Evidences of Christianity,' and his 'Moral Philosophy'...The
+careful study of these works, without attempting to learn any part by rote,
+was the only part of the academical course which...was of the least use to
+me in the education of my mind."
+
+1831:
+
+Passed the examination for the B.A. degree in January and kept the
+following terms.
+
+"I gained a good place among the oi polloi or crowd of men who do not go in
+for honours."
+
+"I am very busy,...and see a great deal of Henslow, whom I do not know
+whether I love or respect most."
+
+Dec. 27.  "Sailed from England on our circumnavigation," in H.M.S.
+"Beagle", a barque of 235 tons carrying 6 guns, under Capt. FitzRoy.
+
+"There is indeed a tide in the affairs of men."
+
+1836:
+
+Oct. 4.  "Reached Shrewsbury after absence of 5 years and 2 days."
+
+"You cannot imagine how gloriously delightful my first visit was at home;
+it was worth the banishment."
+
+Dec. 13.  Went to live at Cambridge (Fitzwilliam Street).
+
+"The only evil I found in Cambridge was its being too pleasant."
+
+1837:
+
+"On my return home (in the 'Beagle') in the autumn of 1836 I immediately
+began to prepare my journal for publication, and then saw how many facts
+indicated the common descent of species...In July (1837) I opened my first
+note-book for facts in relation to the Origin of Species, about which I had
+long reflected, and never ceased working for the next twenty years...Had
+been greatly struck from about the month of previous March on character of
+South American fossils, and species on Galapagos Archipelago.  These facts
+(especially latter), origin of all my views."
+
+"On March 7, 1837 I took lodgings in (36) Great Marlborough Street in
+London, and remained there for nearly two years, until I was married."
+
+1838:
+
+"In October, that is fifteen months after I had begun my systematic
+enquiry, I happened to read for amusement 'Malthus on Population,' and
+being well prepared to appreciate the struggle for existence which
+everywhere goes on from long-continued observation of the habits of animals
+and plants, it at once struck me that under these circumstances favourable
+variations would tend to be preserved, and unfavourable ones to be
+destroyed.  The result of this would be the formation of new species.  Here
+then I had at last got a theory by which to work; but I was so anxious to
+avoid prejudice, that I determined not for some time to write even the
+briefest sketch of it."
+
+1839:
+
+Married at Maer (Staffordshire) to his first cousin Emma Wedgwood, daughter
+of Josiah Wedgwood.
+
+"I marvel at my good fortune that she, so infinitely my superior in every
+single moral quality, consented to be my wife.  She has been my wise
+adviser and cheerful comforter throughout life, which without her would
+have been during a very long period a miserable one from ill-health.  She
+has earned the love of every soul near her" (Autobiography).
+
+Dec. 31.  "Entered 12 Upper Gower street" (now 110 Gower street, London). 
+"There never was so good a house for me, and I devoutly trust you (his
+future wife) will approve of it equally.  The little garden is worth its
+weight in gold."
+
+Published "Journal and Researches", being Vol. III. of the "Narrative of
+the Surveying Voyage of H.M.S. 'Adventure' and 'Beagle'"...
+
+Publication of the "Zoology of the Voyage of H.M.S. 'Beagle'", Part II.,
+"Mammalia", by G.R. Waterhouse, with a "Notice of their habits and ranges",
+by Charles Darwin.
+
+1840:
+
+Contributed Geological Introduction to Part I. ("Fossil Mammalia") of the
+"Zoology of the Voyage of H.M.S. 'Beagle'" by Richard Owen.
+
+1842:
+
+"In June 1842 I first allowed myself the satisfaction of writing a very
+brief abstract of my (species) theory in pencil in 35 pages; and this was
+enlarged during the summer of 1844 into one of 230 pages, which I had
+fairly copied out and still (1876) possess."  (The first draft of "The
+Origin of Species", edited by Mr Francis Darwin, will be published this
+year (1909) by the Syndics of the Cambridge University Press.)
+
+Sept. 14.  Settled at the village of Down in Kent.
+
+"I think I was never in a more perfectly quiet country."
+
+Publication of "The Structure and Distribution of Coral Reefs"; being Part
+I. of the "Geology of the Voyage of the Beagle".
+
+1844:
+
+Publication of "Geological Observations on the Volcanic Islands visited
+during the Voyage of H.M.S. 'Beagle'"; being Part II. of the "Geology of
+the Voyage of the 'Beagle'".
+
+"I think much more highly of my book on Volcanic Islands since Mr Judd, by
+far the best judge on the subject in England, has, as I hear, learnt much
+from it."  (Autobiography, 1876.)
+
+1845:
+
+Publication of the "Journal of Researches" as a separate book.
+
+1846:
+
+Publication of "Geological Observations on South America"; being Part III.
+of the "Geology of the Voyage of the 'Beagle'".
+
+1851:
+
+Publication of a "Monograph of the Fossil Lepadidae" and of a "Monograph of
+the sub-class Cirripedia".
+
+"I fear the study of the Cirripedia will ever remain 'wholly unapplied,'
+and yet I feel that such study is better than castle-building."
+
+1854:
+
+Publication of Monographs of the Balanidae and Verrucidae.
+
+"I worked steadily on this subject for...eight years, and ultimately
+published two thick volumes, describing all the known living species, and
+two thin quartos on the extinct species...My work was of considerable use
+to me, when I had to discuss in the "Origin of Species" the principles of a
+natural classification.  Nevertheless, I doubt whether the work was worth
+the consumption of so much time."
+
+"From September 1854 I devoted my whole time to arranging my huge pile of
+notes, to observing, and to experimenting in relation to the transmutation
+of species."
+
+1856:
+
+"Early in 1856 Lyell advised me to write out my views pretty fully, and I
+began at once to do so on a scale three or four times as extensive as that
+which was afterwards followed in my 'Origin of Species'."
+
+1858:
+
+Joint paper by Charles Darwin and Alfred Russel Wallace "On the Tendency of
+Species to form Varieties; and on the perpetuation of Varieties and Species
+by Natural Means of Selection," communicated to the Linnean Society by Sir
+Charles Lyell and Sir Joseph Hooker.
+
+"I was at first very unwilling to consent (to the communication of his MS.
+to the Society) as I thought Mr Wallace might consider my doing so
+unjustifiable, for I did not then know how generous and noble was his
+disposition."
+
+"July 20 to Aug. 12 at Sandown (Isle of Wight) began abstract of Species
+book."
+
+1859:
+
+Nov. 24.  Publication of "The Origin of Species" (1250 copies).
+
+"Oh, good heavens, the relief to my head and body to banish the whole
+subject from my mind!...But, alas, how frequent, how almost universal it is
+in an author to persuade himself of the truth of his own dogmas.  My only
+hope is that I certainly see many difficulties of gigantic stature."
+
+1860:
+
+Publication of the second edition of the "Origin" (3000 copies).
+
+Publication of a "Naturalist's Voyage".
+
+1861:
+
+Publication of the third edition of the "Origin" (2000 copies).
+
+"I am going to write a little book...on Orchids, and to-day I hate them
+worse than everything."
+
+1862:
+
+Publication of the book "On the various contrivances by which Orchids are
+fertilised by Insects".
+
+1865:
+
+Read paper before the Linnean Society "On the Movements and Habits of
+Climbing plants".  (Published as a book in 1875.)
+
+1866:
+
+Publication of the fourth edition of the "Origin" (1250 copies).
+
+1868:
+
+"I have sent the MS. of my big book, and horridly, disgustingly big it will
+be, to the printers."
+
+Publication of the "Variation of Animals and Plants under Domestication".
+
+"About my book, I will give you (Sir Joseph Hooker) a bit of advice.  Skip
+the whole of Vol. I, except the last chapter, (and that need only be
+skimmed), and skip largely in the 2nd volume; and then you will say it is a
+very good book."
+
+"Towards the end of the work I give my well-abused hypothesis of
+Pangenesis.  An unverified hypothesis is of little or no value; but if
+anyone should hereafter be led to make observations by which some such
+hypothesis could be 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 forms--often very subtle--which 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 individual--if that be not a
+contradiction in terms--no 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 biological
+history," it is also true that the general idea of organic evolution is
+very ancient.  In his admirable sketch "From the Greeks to Darwin"
+("Columbia University Biological Series", Vol. I. New York and London,
+1894.  We must acknowledge our great indebtness to this fine piece of
+work.), Prof. Osborn has shown that several of the ancient philosophers
+looked upon Nature as a gradual development and as still in process of
+change.  In the suggestions of Empedocles, to take the best instance, there
+were "four sparks of truth,--first, that the development of life was a
+gradual process; second, that plants were evolved before animals; third,
+that imperfect forms were gradually replaced (not succeeded) by perfect
+forms; fourth, that the natural cause of the production of perfect forms
+was the extinction of the imperfect."  (Op. cit. page 41.)  But the
+fundamental idea of one stage giving origin to another was absent.  As the
+blue Aegean teemed with treasures of beauty and threw many upon its shores,
+so did Nature produce like a fertile artist what had to be rejected as well
+as what was able to survive, but the idea of one species emerging out of
+another was not yet conceived.
+
+Aristotle's views of Nature (See G.J. Romanes, "Aristotle as a Naturalist",
+"Contemporary Review", Vol. LIX. page 275, 1891; G. Pouchet "La Biologie
+Aristotelique", Paris, 1885; E. Zeller, "A History of Greek Philosophy",
+London, 1881, and "Ueber die griechischen Vorganger Darwin's", "Abhandl.
+Berlin Akad." 1878, pages 111-124.) seem to have been more definitely
+evolutionist than those of his predecessors, in this sense, at least, that
+he recognised not only an ascending scale, but a genetic series from polyp
+to man and an age-long movement towards perfection.  "It is due to the
+resistance of matter to form that Nature can only rise by degrees from
+lower to higher types."  "Nature produces those things which, being
+continually moved by a certain principle contained in themselves, arrive at
+a certain end."
+
+To discern the outcrop of evolution-doctrine in the long interval between
+Aristotle and Bacon seems to be very difficult, and some of the instances
+that have been cited strike one as forced.  Epicurus and Lucretius, often
+called poets of evolution, both pictured animals as arising directly out of
+the earth, very much as Milton's lion long afterwards pawed its way out. 
+Even when we come to Bruno who wrote that "to the sound of the harp of the
+Universal Apollo (the World Spirit), the lower organisms are called by
+stages to higher, and the lower stages are connected by intermediate forms
+with the higher," there is great room, as Prof. Osborn points out (op. cit.
+page 81.), for difference of opinion as to how far he was an evolutionist
+in our sense of the term.
+
+The awakening of natural science in the sixteenth century brought the
+possibility of a concrete evolution theory nearer, and in the early
+seventeenth century we find evidences of a new spirit--in the embryology of
+Harvey and the classifications of Ray.  Besides sober naturalists there
+were speculative dreamers in the sixteenth and seventeenth centuries who
+had at least got beyond static formulae, but, as Professor Osborn points
+out (op. cit. page 87.), "it is a very striking fact, that the basis of our
+modern methods of studying the Evolution problem was established not by the
+early naturalists nor by the speculative writers, but by the Philosophers." 
+He refers to Bacon, Descartes, Leibnitz, Hume, Kant, Lessing, Herder, and
+Schelling.  "They alone were upon the main track of modern thought.  It is
+evident that they were groping in the dark for a working theory of the
+Evolution of life, and it is remarkable that they clearly perceived from
+the outset that the point to which observation should be directed was not
+the past but the present mutability of species, and further, that this
+mutability was simply the variation of individuals on an extended scale."
+
+Bacon seems to have been one of the first to think definitely about the
+mutability of species, and he was far ahead of his age in his suggestion of
+what we now call a Station of Experimental Evolution.  Leibnitz discusses
+in so many words how the species of animals may be changed and how
+intermediate species may once have linked those that now seem
+discontinuous.  "All natural orders of beings present but a single
+chain"..."All advances by degrees in Nature, and nothing by leaps." 
+Similar evolutionist statements are to be found in the works of the other
+"philosophers," to whom Prof. Osborn refers, who were, indeed, more
+scientific than the naturalists of their day.  It must be borne in mind
+that the general idea of organic evolution--that the present is the child
+of the past--is in great part just the idea of human history projected upon
+the natural world, differentiated by the qualification that the continuous
+"Becoming" has been wrought out by forces inherent in the organisms
+themselves and in their environment.
+
+A reference to Kant (See Brock, "Die Stellung Kant's zur
+Deszendenztheorie," "Biol. Centralbl." VIII. 1889, pages 641-648.  Fritz
+Schultze, "Kant und Darwin", Jena, 1875.) should come in historical order
+after Buffon, with whose writings he was acquainted, but he seems, along
+with Herder and Schelling, to be best regarded as the culmination of the
+evolutionist philosophers--of those at least who interested themselves in
+scientific problems.  In a famous passage he speaks of "the agreement of so
+many kinds of animals in a certain common plan of structure"...an "analogy
+of forms" which "strengthens the supposition that they have an actual
+blood-relationship, due to derivation from a common parent."  He speaks of
+"the great Family of creatures, for as a Family we must conceive it, if the
+above-mentioned continuous and connected relationship has a real
+foundation."  Prof. Osborn alludes to the scientific caution which led
+Kant, biology being what it was, to refuse to entertain the hope "that a
+Newton may one day arise even to make the production of a blade of grass
+comprehensible, according to natural laws ordained by no intention."  As
+Prof. Haeckel finely observes, Darwin rose up as Kant's Newton.  (Mr Alfred
+Russel Wallace writes:  "We claim for Darwin that he is the Newton of
+natural history, and that, just so surely as that the discovery and
+demonstration by Newton of the law of gravitation established order in
+place of chaos and laid a sure foundation for all future study of the
+starry heavens, so surely has Darwin, by his discovery of the law of
+natural selection and his demonstration of the great principle of the
+preservation of useful variations in the struggle for life, not only thrown
+a flood of light on the process of development of the whole organic world,
+but also established a firm foundation for all future study of nature"
+("Darwinism", London, 1889, page 9).  See also Prof. Karl Pearson's
+"Grammar of Science" (2nd edition), London, 1900, page 32.  See Osborn, op.
+cit.  Page 100.))
+
+The scientific renaissance brought a wealth of fresh impressions and some
+freedom from the tyranny of tradition, and the twofold stimulus stirred the
+speculative activity of a great variety of men from old Claude Duret of
+Moulins, of whose weird transformism (1609) Dr Henry de Varigny
+("Experimental Evolution".  London, 1892.  Chap. 1. page 14.) gives us a
+glimpse, to Lorenz Oken (1799-1851) whose writings are such mixtures of
+sense and nonsense that some regard him as a far-seeing prophet and others
+as a fatuous follower of intellectual will-o'-the-wisps.  Similarly, for De
+Maillet, Maupertuis, Diderot, Bonnet, and others, we must agree with
+Professor Osborn that they were not actually in the main Evolution
+movement.  Some have been included in the roll of honour on very slender
+evidence, Robinet for instance, whose evolutionism seems to us extremely
+dubious.  (See J. Arthur Thomson, "The Science of Life".  London, 1899. 
+Chap. XVI. "Evolution of Evolution Theory".)
+
+The first naturalist to give a broad and concrete expression to the
+evolutionist doctrine of descent was Buffon (1707-1788), but it is
+interesting to recall the fact that his contemporary Linnaeus (1707-1778),
+protagonist of the counter-doctrine of the fixity of species (See Carus
+Sterne (Ernest Krause), "Die allgemeine Weltanschauung in ihrer
+historischen Entwickelung".  Stuttgart, 1889.  Chapter entitled
+"Bestandigkeit oder Veranderlichkeit der Naturwesen".), went the length of
+admitting (in 1762) that new species might arise by intercrossing. 
+Buffon's position among the pioneers of the evolution-doctrine is weakened
+by his habit of vacillating between his own conclusions and the orthodoxy
+of the Sorbonne, but there is no doubt that he had a firm grasp of the
+general idea of "l'enchainement des etres."
+
+Erasmus Darwin (1731-1802), probably influenced by Buffon, was another firm
+evolutionist, and the outline of his argument in the "Zoonomia" ("Zoonomia,
+or the Laws of Organic Life", 2 vols.  London, 1794; Osborn op. cit. page
+145.) might serve in part at least to-day.  "When we revolve in our minds
+the metamorphoses of animals, as from the tadpole to the frog; secondly,
+the changes produced by artificial cultivation, as in the breeds of horses,
+dogs, and sheep; thirdly, the changes produced by conditions of climate and
+of season, as in the sheep of warm climates being covered with hair instead
+of wool, and the hares and partridges of northern climates becoming white
+in winter:  when, further, we observe the changes of structure produced by
+habit, as seen especially in men of different occupations; or the changes
+produced by artificial mutilation and prenatal influences, as in the
+crossing of species and production of monsters; fourth, when we observe the
+essential unity of plan in all warm-blooded animals,--we are led to
+conclude that they have been alike produced from a similar living
+filament"..."From thus meditating upon the minute portion of time in which
+many of the above changes have been produced, would it be too bold to
+imagine, in the great length of time since the earth began to exist,
+perhaps millions of years before the commencement of the history of
+mankind, that all warm-blooded animals have arisen from one living
+filament?"..."This idea of the gradual generation of all things seems to
+have been as familiar to the ancient philosophers as to the modern ones,
+and to have given rise to the beautiful hieroglyphic figure of the proton
+oon, or first great egg, produced by night, that is, whose origin is
+involved in obscurity, and animated by Eros, that is, by Divine Love; from
+whence proceeded all things which exist."
+
+Lamarck (1744-1829) seems to have become an evolutionist independently of
+Erasmus Darwin's influence, though the parallelism between them is
+striking.  He probably owed something to Buffon, but he developed his
+theory along a different line.  Whatever view be held in regard to that
+theory there is no doubt that Lamarck was a thorough-going evolutionist. 
+Professor Haeckel speaks of the "Philosophie Zoologique" as "the first
+connected and thoroughly logical exposition of the theory of descent." 
+(See Alpheus S. Packard, "Lamarck, the Founder of Evolution, His Life and
+Work, with Translations of his writings on Organic Evolution".  London,
+1901.)
+
+Besides the three old masters, as we may call them, Buffon, Erasmus Darwin,
+and Lamarck, there were other quite convinced pre-Darwinian evolutionists. 
+The historian of the theory of descent must take account of Treviranus
+whose "Biology or Philosophy of Animate Nature" is full of evolutionary
+suggestions; of Etienne Geoffroy St Hilaire, who in 1830, before the French
+Academy of Sciences, fought with Cuvier, the fellow-worker of his youth, an
+intellectual duel on the question of descent; of Goethe, one of the
+founders of morphology and the greatest poet of Evolution--who, in his
+eighty-first year, heard the tidings of Geoffroy St Hilaire's defeat with
+an interest which transcended the political anxieties of the time; and of
+many others who had gained with more or less confidence and clearness a new
+outlook on Nature.  It will be remembered that Darwin refers to thirty-four
+more or less evolutionist authors in his Historical Sketch, and the list
+might be added to.  Especially when we come near to 1858 do the numbers
+increase, and one of the most remarkable, as also most independent
+champions of the evolution-idea before that date was Herbert Spencer, who
+not only marshalled the arguments in a very forcible way in 1852, but
+applied the formula in detail in his "Principles of Psychology" in 1855. 
+(See Edward Clodd, "Pioneers of Evolution", London, page 161, 1897.)
+
+It is right and proper that we should shake ourselves free from all
+creationist appreciations of Darwin, and that we should recognise the
+services of pre-Darwinian evolutionists who helped to make the time ripe,
+yet one cannot help feeling that the citation of them is apt to suggest two
+fallacies.  It may suggest that Darwin simply entered into the labours of
+his predecessors, whereas, as a matter of fact, he knew very little about
+them till after he had been for years at work.  To write, as Samuel Butler
+did, "Buffon planted, Erasmus Darwin and Lamarck watered, but it was Mr
+Darwin who said 'That fruit is ripe,' and shook it into his lap"...seems to
+us a quite misleading version of the facts of the case.  The second fallacy
+which the historical citation is a little apt to suggest is that the
+filiation of ideas is a simple problem.  On the contrary, the history of an
+idea, like the pedigree of an organism, is often very intricate, and the
+evolution of the evolution-idea is bound up with the whole progress of the
+world.  Thus in order to interpret Darwin's clear formulation of the idea
+of organic evolution and his convincing presentation of it, we have to do
+more than go back to his immediate predecessors, such as Buffon, Erasmus
+Darwin, and Lamarck; we have to inquire into the acceptance of evolutionary
+conceptions in regard to other orders of facts, such as the earth and the
+solar system (See Chapter IX. "The Genetic View of Nature" in J.T. Merz's
+"History of European Thought in the Nineteenth Century", Vol. 2, Edinburgh
+and London, 1903.); we have to realise how the growing success of
+scientific interpretation along other lines gave confidence to those who
+refused to admit that there was any domain from which science could be
+excluded as a trespasser; we have to take account of the development of
+philosophical thought, and even of theological and religious movements; we
+should also, if we are wise enough, consider social changes.  In short, we
+must abandon the idea that we can understand the history of any science as
+such, without reference to contemporary evolution in other departments of
+activity.
+
+While there were many evolutionists before Darwin, few of them were expert
+naturalists and few were known outside a small circle; what was of much
+more importance was that the genetic view of nature was insinuating itself
+in regard to other than biological orders of facts, here a little and there
+a little, and that the scientific spirit had ripened since the days when
+Cuvier laughed Lamarck out of court.  How was it that Darwin succeeded
+where others had failed?  Because, in the first place, he had clear
+visions--"pensees de la jeunesse, executees par l'age mur"--which a
+University curriculum had not made impossible, which the "Beagle" voyage
+made vivid, which an unrivalled British doggedness made real--visions of
+the web of life, of the fountain of change within the organism, of the
+struggle for existence and its winnowing, and of the spreading genealogical
+tree.  Because, in the second place, he put so much grit into the
+verification of his visions, putting them to the proof in an argument which
+is of its kind--direct demonstration being out of the question--quite
+unequalled.  Because, in the third place, he broke down the opposition
+which the most scientific had felt to the seductive modal formula of
+evolution by bringing forward a more plausible theory of the process than
+had been previously suggested.  Nor can one forget, since questions of this
+magnitude are human and not merely academic, that he wrote so that all men
+could understand.
+
+AS REGARDS THE FACTORS OF EVOLUTION.
+
+It is admitted by all who are acquainted with the history of biology that
+the general idea of organic evolution as expressed in the Doctrine of
+Descent was quite familiar to Darwin's grandfather, and to others before
+and after him, as we have briefly indicated.  It must also be admitted that
+some of these pioneers of evolutionism did more than apply the evolution-
+idea as a modal formula of becoming, they began to inquire into the factors
+in the process.  Thus there were pre-Darwinian theories of evolution, and
+to these we must now briefly refer.  (See Prof. W.A. Locy's "Biology and
+its Makers".  New York, 1908.  Part II.  "The Doctrine of Organic
+Evolution".
+
+In all biological thinking we have to work with the categories Organism--
+Function--Environment, and theories of evolution may be classified in
+relation to these.  To some it has always seemed that the fundamental fact
+is the living organism,--a creative agent, a striving will, a changeful
+Proteus, selecting its environment, adjusting itself to it, self-
+differentiating and self-adaptive.  The necessity of recognising the
+importance of the organism is admitted by all Darwinians who start with
+inborn variations, but it is open to question whether the whole truth of
+what we might call the Goethian position is exhausted in the postulate of
+inherent variability.
+
+To others it has always seemed that the emphasis should be laid on
+Function,--on use and disuse, on doing and not doing.  Practice makes
+perfect; c'est a force de forger qu'on devient forgeron.  This is one of
+the fundamental ideas of Lamarckism; to some extent it met with Darwin's
+approval; and it finds many supporters to-day.  One of the ablest of these
+--Mr Francis Darwin--has recently given strong reasons for combining a
+modernised Lamarckism with what we usually regard as sound Darwinism. 
+(Presidential Address to the British Association meeting at Dublin in
+1908.)
+
+To others it has always seemed that the emphasis should be laid on the
+Environment, which wakes the organism to action, prompts it to change,
+makes dints upon it, moulds it, prunes it, and finally, perhaps, kills it.
+It is again impossible to doubt that there is truth in this view, for even
+if environmentally induced "modifications" be not transmissible,
+environmentally induced "variations" are; and even if the direct influence
+of the environment be less important than many enthusiastic supporters of
+this view--may we call them Buffonians--think, there remains the indirect
+influence which Darwinians in part rely on,--the eliminative process.  Even
+if the extreme view be held that the only form of discriminate elimination
+that counts is inter-organismal competition, this might be included under
+the rubric of the animate environment.
+
+In many passages Buffon (See in particular Samuel Butler, "Evolution Old
+and New", London, 1879; J.L. de Lanessan, "Buffon et Darwin", "Revue
+Scientifique", XLIII. pages 385-391, 425-432, 1889.) definitely suggested
+that environmental influences--especially of climate and food--were
+directly productive of changes in organisms, but he did not discuss the
+question of the transmissibility of the modifications so induced, and it is
+difficult to gather from his inconsistent writings what extent of
+transformation he really believed in.  Prof. Osborn says of Buffon:  "The
+struggle for existence, the elimination of the least-perfected species, the
+contest between the fecundity of certain species and their constant
+destruction, are all clearly expressed in various passages."  He quotes two
+of these (op. cit. page 136.):
+
+"Le cours ordinaire de la nature vivante, est en general toujours constant,
+toujours le meme; son mouvement, toujours regulier, roule sur deux points
+inebranlables: l'un, la fecondite sans bornes donnee a toutes les especes;
+l'autre, les obstacles sans nombre qui reduisent cette fecondite a une
+mesure determinee et ne laissent en tout temps qu'a peu pres la meme
+quantite d'individus de chaque espece"..."Les especes les moins parfaites,
+les plus delicates, les plus pesantes, les moins agissantes, les moins
+armees, etc., ont deja disparu ou disparaitront."
+
+Erasmus Darwin (See Ernst Krause and Charles Darwin, "Erasmus Darwin",
+London, 1879.) had a firm grip of the "idea of the gradual formation and
+improvement of the Animal world," and he had his theory of the process.  No
+sentence is more characteristic than this:  "All animals undergo
+transformations which are in part produced by their own exertions, in
+response to pleasures and pains, and many of these acquired forms or
+propensities are transmitted to their posterity."  This is Lamarckism
+before Lamarck, as his grandson pointed out.  His central idea is that
+wants stimulate efforts and that these result in improvements, which
+subsequent generations make better still.  He realised something of the
+struggle for existence and even pointed out that this advantageously checks
+the rapid multiplication.  "As Dr Krause points out, Darwin just misses the
+connection between this struggle and the Survival of the Fittest."  (Osborn
+op. cit. page 142.)
+
+Lamarck (1744-1829) (See E. Perrier "La Philosophie Zoologique avant
+Darwin", Paris, 1884; A. de Quatrefages, "Darwin et ses Precurseurs
+Francais", Paris, 1870; Packard op. cit.; also Claus, "Lamarck als
+Begrunder der Descendenzlehre", Wien, 1888; Haeckel, "Natural History of
+Creation", English translation London, 1879; Lang "Zur Charakteristik der
+Forschungswege von Lamarck und Darwin", Jena, 1889.) seems to have thought
+out his theory of evolution without any knowledge of Erasmus Darwin's which
+it closely resembled.  The central idea of his theory was the cumulative
+inheritance of functional modifications.  "Changes in environment bring
+about changes in the habits of animals.  Changes in their wants necessarily
+bring about parallel changes in their habits.  If new wants become constant
+or very lasting, they form new habits, the new habits involve the use of
+new parts, or a different use of old parts, which results finally in the
+production of new organs and the modification of old ones."  He differed
+from Buffon in not attaching importance, as far as animals are concerned,
+to the direct influence of the environment, "for environment can effect no
+direct change whatever upon the organisation of animals," but in regard to
+plants he agreed with Buffon that external conditions directly moulded
+them.
+
+Treviranus (1776-1837) (See Huxley's article "Evolution in Biology",
+"Encyclopaedia Britannica" (9th edit.), 1878, pages 744-751, and Sully's
+article, "Evolution in Philosophy", ibid. pages 751-772.), whom Huxley
+ranked beside Lamarck, was on the whole Buffonian, attaching chief
+importance to the influence of a changeful environment both in modifying
+and in eliminating, but he was also Goethian, for instance in his idea that
+species like individuals pass through periods of growth, full bloom, and
+decline.  "Thus, it is not only the great catastrophes of Nature which have
+caused extinction, but the completion of cycles of existence, out of which
+new cycles have begun."  A characteristic sentence is quoted by Prof.
+Osborn:  "In every living being there exists a capability of an endless
+variety of form-assumption; each possesses the power to adapt its
+organisation to the changes of the outer world, and it is this power, put
+into action by the change of the universe, that has raised the simple
+zoophytes of the primitive world to continually higher stages of
+organisation, and has introduced a countless variety of species into
+animate Nature."
+
+Goethe (1749-1832) (See Haeckel, "Die Naturanschauung von Darwin, Goethe
+und Lamarck", Jena, 1882.), who knew Buffon's work but not Lamarck's, is
+peculiarly interesting as one of the first to use the evolution-idea as a
+guiding hypothesis, e.g. in the interpretation of vestigial structures in
+man, and to realise that organisms express an attempt to make a compromise
+between specific inertia and individual change.  He gave the finest
+expression that science has yet known--if it has known it--of the kernel-
+idea of what is called "bathmism," the idea of an "inherent growth-force"--
+and at the same time he held that "the way of life powerfully reacts upon
+all form" and that the orderly growth of form "yields to change from
+externally acting causes."
+
+Besides Buffon, Erasmus Darwin, Lamarck, Treviranus, and Goethe, there were
+other "pioneers of evolution," whose views have been often discussed and
+appraised.  Etienne Geoffroy Saint-Hilaire (1772-1844), whose work Goethe
+so much admired, was on the whole Buffonian, emphasising the direct action
+of the changeful milieu.  "Species vary with their environment, and
+existing species have descended by modification from earlier and somewhat
+simpler species."  He had a glimpse of the selection idea, and believed in
+mutations or sudden leaps--induced in the embryonic condition by external
+influences.  The complete history of evolution-theories will include many
+instances of guesses at truth which were afterwards substantiated, thus the
+geographer von Buch (1773-1853) detected the importance of the Isolation
+factor on which Wagner, Romanes, Gulick and others have laid great stress,
+but we must content ourselves with recalling one other pioneer, the author
+of the "Vestiges of Creation" (1844), a work which passed through ten
+editions in nine years and certainly helped to harrow the soil for Darwin's
+sowing.  As Darwin said, "it did excellent service in this country in
+calling attention to the subject, in removing prejudice, and in thus
+preparing the ground for the reception of analogous views."  ("Origin of
+Species" (6th edition), page xvii.)  Its author, Robert Chambers (1802-
+1871) was in part a Buffonian--maintaining that environment moulded
+organisms adaptively, and in part a Goethian--believing in an inherent
+progressive impulse which lifted organisms from one grade of organisation
+to another.
+
+AS REGARDS NATURAL SELECTION.
+
+The only thinker to whom Darwin was directly indebted, so far as the theory
+of Natural Selection is concerned, was Malthus, and we may once more quote
+the well-known passage in the Autobiography:  "In October, 1838, that is,
+fifteen months after I had begun my systematic enquiry, I happened to read
+for amusement 'Malthus on Population', and being well prepared to
+appreciate the struggle for existence which everywhere goes on from long-
+continued observation of the habits of animals and plants, it at once
+struck me that under these circumstances favourable variations would tend
+to be preserved, and unfavourable ones to be destroyed.  The result of this
+would be the formation of new species."  ("The Life and Letters of Charles
+Darwin", Vol. 1. page 83.  London, 1887.)
+
+Although Malthus gives no adumbration of the idea of Natural Selection in
+his exposition of the eliminative processes which go on in mankind, the
+suggestive value of his essay is undeniable, as is strikingly borne out by
+the fact that it gave to Alfred Russel Wallace also "the long-sought clue
+to the effective agent in the evolution of organic species."  (A.R.
+Wallace, "My Life, A Record of Events and Opinions", London, 1905, Vol. 1.
+page 232.)  One day in Ternate when he was resting between fits of fever,
+something brought to his recollection the work of Malthus which he had read
+twelve years before.  "I thought of his clear exposition of 'the positive
+checks to increase'--disease, accidents, war, and famine--which keep down
+the population of savage races to so much lower an average than that of
+more civilized peoples.  It then occurred to me that these causes or their
+equivalents are continually acting in the case of animals also; and as
+animals usually breed much more rapidly than does mankind, the destruction
+every year from these causes must be enormous in order to keep down the
+numbers of each species, since they evidently do not increase regularly
+from year to year, as otherwise the world would long ago have been densely
+crowded with those that breed most quickly.  Vaguely thinking over the
+enormous and constant destruction which this implied, it occurred to me to
+ask the question, Why do some die and some live?  And the answer was
+clearly, that on the whole the best fitted live.  From the effects of
+disease the most healthy escaped; from enemies the strongest, the swiftest,
+or the most cunning; from famine the best hunters or those with the best
+digestion; and so on.  Then it suddenly flashed upon me that this self-
+acting process would necessarily IMPROVE THE RACE, because in every
+generation the inferior would inevitably be killed off and the superior
+would remain--that is, THE FITTEST WOULD SURVIVE."  (Ibid. Vol. 1. page
+361.)  We need not apologise for this long quotation, it is a tribute to
+Darwin's magnanimous colleague, the Nestor of the evolutionist camp,--and
+it probably indicates the line of thought which Darwin himself followed. 
+It is interesting also to recall the fact that in 1852, when Herbert
+Spencer wrote his famous "Leader" article on "The Development Hypothesis"
+in which he argued powerfully for the thesis that the whole animate world
+is the result of an age-long process of natural transformation, he wrote
+for "The Westminster Review" another important essay, "A Theory of
+Population deduced from the General Law of Animal Fertility", towards the
+close of which he came within an ace of recognising that the struggle for
+existence was a factor in organic evolution.  At a time when pressure of
+population was practically interesting men's minds, Darwin, Wallace, and
+Spencer were being independently led from a social problem to a biological
+theory.  There could be no better illustration, as Prof. Patrick Geddes has
+pointed out, of the Comtian thesis that science is a "social phenomenon."
+
+Therefore, as far more important than any further ferreting out of vague
+hints of Natural Selection in books which Darwin never read, we would
+indicate by a quotation the view that the central idea in Darwinism is
+correlated with contemporary social evolution.  "The substitution of Darwin
+for Paley as the chief interpreter of the order of nature is currently
+regarded as the displacement of an anthropomorphic view by a purely
+scientific one:  a little reflection, however, will show that what has
+actually happened has been merely the replacement of the anthropomorphism
+of the eighteenth century by that of the nineteenth.  For the place vacated
+by Paley's theological and metaphysical explanation has simply been
+occupied by that suggested to Darwin and Wallace by Malthus in terms of the
+prevalent severity of industrial competition, and those phenomena of the
+struggle for existence which the light of contemporary economic theory has
+enabled us to discern, have thus come to be temporarily exalted into a
+complete explanation of organic progress."  (P. Geddes, article "Biology",
+"Chambers's Encyclopaedia".)  It goes without saying that the idea
+suggested by Malthus was developed by Darwin into a biological theory which
+was then painstakingly verified by being used as an interpretative formula,
+and that the validity of a theory so established is not affected by what
+suggested it, but the practical question which this line of thought raises
+in the mind is this:  if Biology did thus borrow with such splendid results
+from social theory, why should we not more deliberately repeat the
+experiment?
+
+Darwin was characteristically frank and generous in admitting that the
+principle of Natural Selection had been independently recognised by Dr W.C.
+Wells in 1813 and by Mr Patrick Matthew in 1831, but he had no knowledge of
+these anticipations when he published the first edition of "The Origin of
+Species".  Wells, whose "Essay on Dew" is still remembered, read in 1813
+before the Royal Society a short paper entitled "An account of a White
+Female, part of whose skin resembles that of a Negro" (published in 1818). 
+In this communication, as Darwin said, "he observes, firstly, that all
+animals tend to vary in some degree, and, secondly, that agriculturists
+improve their domesticated animals by selection; and then, he adds, but
+what is done in this latter case 'by art, seems to be done with equal
+efficacy, though more slowly, by nature, in the formation of varieties of
+mankind, fitted for the country which they inhabit.'"  ("Origin of Species"
+(6th edition) page xv.)  Thus Wells had the clear idea of survival
+dependent upon a favourable variation, but he makes no more use of the idea
+and applies it only to man.  There is not in the paper the least hint that
+the author ever thought of generalising the remarkable sentence quoted
+above.
+
+Of Mr Patrick Matthew, who buried his treasure in an appendix to a work on
+"Naval Timber and Arboriculture", Darwin said that "he clearly saw the full
+force of the principle of natural selection."  In 1860 Darwin wrote--very
+characteristically--about this to Lyell:  "Mr Patrick Matthew publishes a
+long extract from his work on "Naval Timber and Arboriculture", published
+in 1831, in which he briefly but completely anticipates the theory of
+Natural Selection.  I have ordered the book, as some passages are rather
+obscure, but it is certainly, I think, a complete but not developed
+anticipation.  Erasmus always said that surely this would be shown to be
+the case some day.  Anyhow, one may be excused in not having discovered the
+fact in a work on Naval Timber."  ("Life and Letters" II. page 301.)
+
+De Quatrefages and De Varigny have maintained that the botanist Naudin
+stated the theory of evolution by natural selection in 1852.  He explains
+very clearly the process of artificial selection, and says that in the
+garden we are following Nature's method.  "We do not think that Nature has
+made her species in a different fashion from that in which we proceed
+ourselves in order to make our variations."  But, as Darwin said, "he does
+not show how selection acts under nature."  Similarly it must be noted in
+regard to several pre-Darwinian pictures of the struggle for existence
+(such as Herder's, who wrote in 1790 "All is in struggle...each one for
+himself" and so on), that a recognition of this is only the first step in
+Darwinism.
+
+Profs. E. Perrier and H.F. Osborn have called attention to a remarkable
+anticipation of the selection-idea which is to be found in the speculations
+of Etienne Geoffroy St Hilaire (1825-1828) on the evolution of modern
+Crocodilians from the ancient Teleosaurs.  Changing environment induced
+changes in the respiratory system and far-reaching consequences followed. 
+The atmosphere, acting upon the pulmonary cells, brings about
+"modifications which are favourable or destructive ('funestes'); these are
+inherited, and they influence all the rest of the organisation of the
+animal because if these modifications lead to injurious effects, the
+animals which exhibit them perish and are replaced by others of a somewhat
+different form, a form changed so as to be adapted to (a la convenance) the
+new environment."
+
+Prof. E.B. Poulton ("Science Progress", New Series, Vol. I. 1897.  "A
+Remarkable Anticipation of Modern Views on Evolution".  See also Chap. VI.
+in "Essays on Evolution", Oxford, 1908.) has shown that the anthropologist
+James Cowles Prichard (1786-1848) must be included, even in spite of
+himself, among the precursors of Darwin.  In some passages of the second
+edition of his "Researches into the Physical History of Mankind" (1826), he
+certainly talks evolution and anticipates Prof. Weismann in denying the
+transmission of acquired characters.  He is, however, sadly self-
+contradictory and his evolutionism weakens in subsequent editions--the only
+ones that Darwin saw.  Prof. Poulton finds in Prichard's work a recognition
+of the operation of Natural Selection.  "After enquiring how it is that
+'these varieties are developed and preserved in connection with particular
+climates and differences of local situation,' he gives the following very
+significant answer:  'One cause which tends to maintain this relation is
+obvious.  Individuals and families, and even whole colonies, perish and
+disappear in climates for which they are, by peculiarity of constitution,
+not adapted.  Of this fact proofs have been already mentioned.'"  Mr
+Francis Darwin and Prof. A.C. Seward discuss Prichard's "anticipations" in
+"More Letters of Charles Darwin", Vol. I. page 43, and come to the
+conclusion that the evolutionary passages are entirely neutralised by
+others of an opposite trend.  There is the same difficulty with Buffon.
+
+Hints of the idea of Natural Selection have been detected elsewhere.  James
+Watt (See Prof. Patrick Geddes's article "Variation and Selection",
+"Encyclopaedia Britannica (9th edition) 1888.), for instance, has been
+reported as one of the anticipators (1851).  But we need not prolong the
+inquiry further, since Darwin did not know of any anticipations until after
+he had published the immortal work of 1859, and since none of those who got
+hold of the idea made any use of it.  What Darwin did was to follow the
+clue which Malthus gave him, to realise, first by genius and afterwards by
+patience, how the complex and subtle struggle for existence works out a
+natural selection of those organisms which vary in the direction of fitter
+adaptation to the conditions of their life.  So much success attended his
+application of the Selection-formula that for a time he regarded Natural
+Selection as almost the sole factor in evolution, variations being pre-
+supposed; gradually, however, he came to recognise that there was some
+validity in the factors which had been emphasized by Lamarck and by Buffon,
+and in his well-known summing up in the sixth edition of the "Origin" he
+says of the transformation of species:  "This has been effected chiefly
+through the natural selection of numerous successive, slight, favourable
+variations; aided in an important manner by the inherited effects of the
+use and disuse of parts; and in an unimportant manner, that is, in relation
+to adaptive structures, whether past or present, by the direct action of
+external conditions, and by variations which seem to us in our ignorance to
+arise spontaneously."
+
+To sum up:  the idea of organic evolution, older than Aristotle, slowly
+developed from the stage of suggestion to the stage of verification, and
+the first convincing verification was Darwin's; from being an a priori
+anticipation it has become an interpretation of nature, and Darwin is still
+the chief interpreter; from being a modal interpretation it has advanced to
+the rank of a causal theory, the most convincing part of which men will
+never cease to call Darwinism.
+
+
+III.  THE SELECTION THEORY
+
+By August Weismann.
+Professor of Zoology in the University of Freiburg (Baden).
+
+I.  THE IDEA OF SELECTION.
+
+Many and diverse were the discoveries made by Charles Darwin in the course
+of a long and strenuous life, but none of them has had so far-reaching an
+influence on the science and thought of his time as the theory of
+selection.  I do not believe that the theory of evolution would have made
+its way so easily and so quickly after Darwin took up the cudgels in favour
+of it, if he had not been able to support it by a principle which was
+capable of solving, in a simple manner, the greatest riddle that living
+nature presents to us,--I mean the purposiveness of every living form
+relative to the conditions of its life and its marvellously exact
+adaptation to these.
+
+Everyone knows that Darwin was not alone in discovering the principle of
+selection, and that the same idea occurred simultaneously and independently
+to Alfred Russel Wallace.  At the memorable meeting of the Linnean Society
+on 1st July, 1858, two papers were read (communicated by Lyell and Hooker)
+both setting forth the same idea of selection.  One was written by Charles
+Darwin in Kent, the other by Alfred Wallace in Ternate, in the Malay
+Archipelago.  It was a splendid proof of the magnanimity of these two
+investigators, that they thus, in all friendliness and without envy, united
+in laying their ideas before a scientific tribunal:  their names will
+always shine side by side as two of the brightest stars in the scientific
+sky.
+
+But it is with Charles Darwin that I am here chiefly concerned, since this
+paper is intended to aid in the commemoration of the hundredth anniversary
+of his birth.
+
+The idea of selection set forth by the two naturalists was at the time
+absolutely new, but it was also so simple that Huxley could say of it
+later, "How extremely stupid not to have thought of that."  As Darwin was
+led to the general doctrine of descent, not through the labours of his
+predecessors in the early years of the century, but by his own
+observations, so it was in regard to the principle of selection.  He was
+struck by the innumerable cases of adaptation, as, for instance, that of
+the woodpeckers and tree-frogs to climbing, or the hooks and feather-like
+appendages of seeds, which aid in the distribution of plants, and he said
+to himself that an explanation of adaptations was the first thing to be
+sought for in attempting to formulate a theory of evolution.
+
+But since adaptations point to CHANGES which have been undergone by the
+ancestral forms of existing species, it is necessary, first of all, to
+inquire how far species in general are VARIABLE.  Thus Darwin's attention
+was directed in the first place to the phenomenon of variability, and the
+use man has made of this, from very early times, in the breeding of his
+domesticated animals and cultivated plants.  He inquired carefully how
+breeders set to work, when they wished to modify the structure and
+appearance of a species to their own ends, and it was soon clear to him
+that SELECTION FOR BREEDING PURPOSES played the chief part.
+
+But how was it possible that such processes should occur in free nature? 
+Who is here the breeder, making the selection, choosing out one individual
+to bring forth offspring and rejecting others?  That was the problem that
+for a long time remained a riddle to him.
+
+Darwin himself relates how illumination suddenly came to him.  He had been
+reading, for his own pleasure, Malthus' book on Population, and, as he had
+long known from numerous observations, that every species gives rise to
+many more descendants than ever attain to maturity, and that, therefore,
+the greater number of the descendants of a species perish without
+reproducing, the idea came to him that the decision as to which member of a
+species was to perish, and which was to attain to maturity and reproduction
+might not be a matter of chance, but might be determined by the
+constitution of the individuals themselves, according as they were more or
+less fitted for survival.  With this idea the foundation of the theory of
+selection was laid.
+
+In ARTIFICIAL SELECTION the breeder chooses out for pairing only such
+individuals as possess the character desired by him in a somewhat higher
+degree than the rest of the race.  Some of the descendants inherit this
+character, often in a still higher degree, and if this method be pursued
+throughout several generations, the race is transformed in respect of that
+particular character.
+
+NATURAL SELECTION depends on the same three factors as ARTIFICIAL
+SELECTION:  on VARIABILITY, INHERITANCE, and SELECTION FOR BREEDING, but
+this last is here carried out not by a breeder but by what Darwin called
+the "struggle for existence."  This last factor is one of the special
+features of the Darwinian conception of nature.  That there are carnivorous
+animals which take heavy toll in every generation of the progeny of the
+animals on which they prey, and that there are herbivores which decimate
+the plants in every generation had long been known, but it is only since
+Darwin's time that sufficient attention has been paid to the facts that, in
+addition to this regular destruction, there exists between the members of a
+species a keen competition for space and food, which limits multiplication,
+and that numerous individuals of each species perish because of
+unfavourable climatic conditions.  The "struggle for existence," which
+Darwin regarded as taking the place of the human breeder in free nature, is
+not a direct struggle between carnivores and their prey, but is the assumed
+competition for survival between individuals OF THE SAME species, of which,
+on an average, only those survive to reproduce which have the greatest
+power of resistance, while the others, less favourably constituted, perish
+early.  This struggle is so keen, that, within a limited area, where the
+conditions of life have long remained unchanged, of every species, whatever
+be the degree of fertility, only two, ON AN AVERAGE, of the descendants of
+each pair survive; the others succumb either to enemies, or to
+disadvantages of climate, or to accident.  A high degree of fertility is
+thus not an indication of the special success of a species, but of the
+numerous dangers that have attended its evolution.  Of the six young
+brought forth by a pair of elephants in the course of their lives only two
+survive in a given area; similarly, of the millions of eggs which two
+thread-worms leave behind them only two survive.  It is thus possible to
+estimate the dangers which threaten a species by its ratio of elimination,
+or, since this cannot be done directly, by its fertility.
+
+Although a great number of the descendants of each generation fall victims
+to accident, among those that remain it is still the greater or lesser
+fitness of the organism that determines the "selection for breeding
+purposes," and it would be incomprehensible if, in this competition, it
+were not ultimately, that is, on an average, the best equipped which
+survive, in the sense of living long enough to reproduce.
+
+Thus the principle of natural selection is THE SELECTION OF THE BEST FOR
+REPRODUCTION, whether the "best" refers to the whole constitution, to one
+or more parts of the organism, or to one or more stages of development. 
+Every organ, every part, every character of an animal, fertility and
+intelligence included, must be improved in this manner, and be gradually
+brought up in the course of generations to its highest attainable state of
+perfection.  And not only may improvement of parts be brought about in this
+way, but new parts and organs may arise, since, through the slow and minute
+steps of individual or "fluctuating" variations, a part may be added here
+or dropped out there, and thus something new is produced.
+
+The principle of selection solved the riddle as to how what was purposive
+could conceivably be brought about without the intervention of a directing
+power, the riddle which animate nature presents to our intelligence at
+every turn, and in face of which the mind of a Kant could find no way out,
+for he regarded a solution of it as not to be hoped for.  For, even if we
+were to assume an evolutionary force that is continually transforming the
+most primitive and the simplest forms of life into ever higher forms, and
+the homogeneity of primitive times into the infinite variety of the
+present, we should still be unable to infer from this alone how each of the
+numberless forms adapted to particular conditions of life should have
+appeared PRECISELY AT THE RIGHT MOMENT IN THE HISTORY OF THE EARTH to which
+their adaptations were appropriate, and precisely at the proper place in
+which all the conditions of life to which they were adapted occurred:  the
+humming-birds at the same time as the flowers; the trichina at the same
+time as the pig; the bark-coloured moth at the same time as the oak, and
+the wasp-like moth at the same time as the wasp which protects it.  Without
+processes of selection we should be obliged to assume a "pre-established
+harmony" after the famous Leibnitzian model, by means of which the clock of
+the evolution of organisms is so regulated as to strike in exact
+synchronism with that of the history of the earth!  All forms of life are
+strictly adapted to the conditions of their life, and can persist under
+these conditions alone.
+
+There must therefore be an intrinsic connection between the conditions and
+the structural adaptations of the organism, and, SINCE THE CONDITIONS OF
+LIFE CANNOT BE DETERMINED BY THE ANIMAL ITSELF, THE ADAPTATIONS MUST BE
+CALLED FORTH BY THE CONDITIONS.
+
+The selection theory teaches us how this is conceivable, since it enables
+us to understand that there is a continual production of what is non-
+purposive as well as of what is purposive, but the purposive alone
+survives, while the non-purposive perishes in the very act of arising. 
+This is the old wisdom taught long ago by Empedocles.
+
+II.  THE LAMARCKIAN PRINCIPLE.
+
+Lamarck, as is well known, formulated a definite theory of evolution at the
+beginning of the nineteenth century, exactly fifty years before the Darwin-
+Wallace principle of selection was given to the world.  This brilliant
+investigator also endeavoured to support his theory by demonstrating forces
+which might have brought about the transformations of the organic world in
+the course of the ages.  In addition to other factors, he laid special
+emphasis on the increased or diminished use of the parts of the body,
+assuming that the strengthening or weakening which takes place from this
+cause during the individual life, could be handed on to the offspring, and
+thus intensified and raised to the rank of a specific character.  Darwin
+also regarded this LAMARCKIAN PRINCIPLE, as it is now generally called, as
+a factor in evolution, but he was not fully convinced of the
+transmissibility of acquired characters.
+
+As I have here to deal only with the theory of selection, I need not
+discuss the Lamarckian hypothesis, but I must express my opinion that there
+is room for much doubt as to the cooperation of this principle in
+evolution.  Not only is it difficult to imagine how the transmission of
+functional modifications could take place, but, up to the present time,
+notwithstanding the endeavours of many excellent investigators, not a
+single actual proof of such inheritance has been brought forward.  Semon's
+experiments on plants are, according to the botanist Pfeffer, not to be
+relied on, and even the recent, beautiful experiments made by Dr Kammerer
+on salamanders, cannot, as I hope to show elsewhere, be regarded as proof,
+if only because they do not deal at all with functional modifications, that
+is, with modifications brought about by use, and it is to these ALONE that
+the Lamarckian principle refers.
+
+III.  OBJECTIONS TO THE THEORY OF SELECTION.
+
+(a)  Saltatory evolution.
+
+The Darwinian doctrine of evolution depends essentially on THE CUMULATIVE
+AUGMENTATION of minute variations in the direction of utility.  But can
+such minute variations, which are undoubtedly continually appearing among
+the individuals of the same species, possess any selection-value; can they
+determine which individuals are to survive, and which are to succumb; can
+they be increased by natural selection till they attain to the highest
+development of a purposive variation?
+
+To many this seems so improbable that they have urged a theory of evolution
+by leaps from species to species.  Kolliker, in 1872, compared the
+evolution of species with the processes which we can observe in the
+individual life in cases of alternation of generations.  But a polyp only
+gives rise to a medusa because it has itself arisen from one, and there can
+be no question of a medusa ever having arisen suddenly and de novo from a
+polyp-bud, if only because both forms are adapted in their structure as a
+whole, and in every detail to the conditions of their life.  A sudden
+origin, in a natural way, of numerous adaptations is inconceivable.  Even
+the degeneration of a medusoid from a free-swimming animal to a mere brood-
+sac (gonophore) is not sudden and saltatory, but occurs by imperceptible
+modifications throughout hundreds of years, as we can learn from the
+numerous stages of the process of degeneration persisting at the same time
+in different species.
+
+If, then, the degeneration to a simple brood-sac takes place only by very
+slow transitions, each stage of which may last for centuries, how could the
+much more complex ASCENDING evolution possibly have taken place by sudden
+leaps?  I regard this argument as capable of further extension, for
+wherever in nature we come upon degeneration, it is taking place by minute
+steps and with a slowness that makes it not directly perceptible, and I
+believe that this in itself justifies us in concluding that THE SAME MUST
+BE TRUE OF ASCENDING evolution.  But in the latter case the goal can seldom
+be distinctly recognised while in cases of degeneration the starting-point
+of the process can often be inferred, because several nearly related
+species may represent different stages.
+
+In recent years Bateson in particular has championed the idea of saltatory,
+or so-called discontinuous evolution, and has collected a number of cases
+in which more or less marked variations have suddenly appeared.  These are
+taken for the most part from among domesticated animals which have been
+bred and crossed for a long time, and it is hardly to be wondered at that
+their much mixed and much influenced germ-plasm should, under certain
+conditions, give rise to remarkable phenomena, often indeed producing forms
+which are strongly suggestive of monstrosities, and which would undoubtedly
+not survive in free nature, unprotected by man.  I should regard such cases
+as due to an intensified germinal selection--though this is to anticipate a
+little--and from this point of view it cannot be denied that they have a
+special interest.  But they seem to me to have no significance as far as
+the transformation of species is concerned, if only because of the extreme
+rarity of their occurrence.
+
+There are, however, many variations which have appeared in a sudden and
+saltatory manner, and some of these Darwin pointed out and discussed in
+detail:  the copper beech, the weeping trees, the oak with "fern-like
+leaves," certain garden-flowers, etc.  But none of them have persisted in
+free nature, or evolved into permanent types.
+
+On the other hand, wherever enduring types have arisen, we find traces of a
+gradual origin by successive stages, even if, at first sight, their origin
+may appear to have been sudden.  This is the case with SEASONAL DIMORPHISM,
+the first known cases of which exhibited marked differences between the two
+generations, the winter and the summer brood.  Take for instance the much
+discussed and studied form Vanessa (Araschnia) levana-prorsa.  Here the
+differences between the two forms are so great and so apparently
+disconnected, that one might almost believe it to be a sudden mutation,
+were it not that old transition-stages can be called forth by particular
+temperatures, and we know other butterflies, as for instance our Garden
+Whites, in which the differences between the two generations are not nearly
+so marked; indeed, they are so little apparent that they are scarcely
+likely to be noticed except by experts.  Thus here again there are small
+initial steps, some of which, indeed, must be regarded as adaptations, such
+as the green-sprinkled or lightly tinted under-surface which gives them a
+deceptive resemblance to parsley or to Cardamine leaves.
+
+Even if saltatory variations do occur, we cannot assume that these HAVE
+EVER LED TO FORMS WHICH ARE CAPABLE OF SURVIVAL UNDER THE CONDITIONS OF
+WILD LIFE.  Experience has shown that in plants which have suddenly varied
+the power of persistence is diminished.  Korschinksky attributes to them
+weaknesses of organisation in general; "they bloom late, ripen few of their
+seeds, and show great sensitiveness to cold."  These are not the characters
+which make for success in the struggle for existence.
+
+We must briefly refer here to the views--much discussed in the last decade
+--of H. de Vries, who believes that the roots of transformation must be
+sought for in SALTATORY VARIATIONS ARISING FROM INTERNAL CAUSES, and
+distinguishes such MUTATIONS, as he has called them, from ordinary
+individual variations, in that they breed true, that is, with strict
+inbreeding they are handed on pure to the next generation.  I have
+elsewhere endeavoured to point out the weaknesses of this theory ("Vortrage
+uber Descendenztheorie", Jena, 1904, II. 269.  English Translation London,
+1904, II. page 317.), and I am the less inclined to return to it here that
+it now appears (See Poulton, "Essays on Evolution", Oxford, 1908, pages
+xix-xxii.) that the far-reaching conclusions drawn by de Vries from his
+observations on the Evening Primrose, Oenothera lamarckiana, rest upon a
+very insecure foundation.  The plant from which de Vries saw numerous
+"species"--his "mutations"--arise was not, as he assumed, a WILD SPECIES
+that had been introduced to Europe from America, but was probably a hybrid
+form which was first discovered in the Jardin des Plantes in Paris, and
+which does not appear to exist anywhere in America as a wild species.
+
+This gives a severe shock to the "Mutation theory," for the other ACTUALLY
+WILD species with which de Vries experimented showed no "mutations" but
+yielded only negative results.
+
+Thus we come to the conclusion that Darwin ("Origin of Species" (6th
+edition), pages 176 et seq.) was right in regarding transformations as
+taking place by minute steps, which, if useful, are augmented in the course
+of innumerable generations, because their possessors more frequently
+survive in the struggle for existence.
+
+(b)  SELECTION-VALUE OF THE INITIAL STEPS.
+
+Is it possible that the significant deviations which we know as "individual
+variations" can form the beginning of a process of selection?  Can they
+decide which is to perish and which to survive?  To use a phrase of
+Romanes, can they have SELECTION-VALUE?
+
+Darwin himself answered this question, and brought together many excellent
+examples to show that differences, apparently insignificant because very
+small, might be of decisive importance for the life of the possessor.  But
+it is by no means enough to bring forward cases of this kind, for the
+question is not merely whether finished adaptations have selection-value,
+but whether the first beginnings of these, and whether the small, I might
+almost say minimal increments, which have led up from these beginnings to
+the perfect adaptation, have also had selection-value.  To this question
+even one who, like myself, has been for many years a convinced adherent of
+the theory of selection, can only reply:  WE MUST ASSUME SO, BUT WE CANNOT
+PROVE IT IN ANY CASE.  It is not upon demonstrative evidence that we rely
+when we champion the doctrine of selection as a scientific truth; we base
+our argument on quite other grounds.  Undoubtedly there are many apparently
+insignificant features, which can nevertheless be shown to be adaptations--
+for instance, the thickness of the basin-shaped shell of the limpets that
+live among the breakers on the shore.  There can be no doubt that the
+thickness of these shells, combined with their flat form, protects the
+animals from the force of the waves breaking upon them,--but how have they
+become so thick?  What proportion of thickness was sufficient to decide
+that of two variants of a limpet one should survive, the other be
+eliminated?  We can say nothing more than that we infer from the present
+state of the shell, that it must have varied in regard to differences in
+shell-thickness, and that these differences must have had selection-value,
+--no proof therefore, but an assumption which we must show to be
+convincing.
+
+For a long time the marvellously complex RADIATE and LATTICE-WORK skeletons
+of Radiolarians were regarded as a mere outflow of "Nature's infinite
+wealth of form," as an instance of a purely morphological character with no
+biological significance.  But recent investigations have shown that these,
+too, have an adaptive significance (Hacker).  The same thing has been shown
+by Schutt in regard to the lowly unicellular plants, the Peridineae, which
+abound alike on the surface of the ocean and in its depths.  It has been
+shown that the long skeletal processes which grow out from these organisms
+have significance not merely as a supporting skeleton, but also as an
+extension of the superficial area, which increases the contact with the
+water-particles, and prevents the floating organisms from sinking.  It has
+been established that the processes are considerably shorter in the colder
+layers of the ocean, and that they may be twelve times as long (Chun,
+"Reise der Valdivia", Leipzig, 1904.) in the warmer layers, thus
+corresponding to the greater or smaller amount of friction which takes
+place in the denser and less dense layers of the water.
+
+The Peridineae of the warmer ocean layers have thus become long-rayed,
+those of the colder layers short-rayed, not through the direct effect of
+friction on the protoplasm, but through processes of selection, which
+favoured the longer rays in warm water, since they kept the organism
+afloat, while those with short rays sank and were eliminated.  If we put
+the question as to selection-value in this case, and ask how great the
+variations in the length of processes must be in order to possess
+selection-value; what can we answer except that these variations must have
+been minimal, and yet sufficient to prevent too rapid sinking and
+consequent elimination?  Yet this very case would give the ideal
+opportunity for a mathematical calculation of the minimal selection-value,
+although of course it is not feasible from lack of data to carry out the
+actual calculation.
+
+But even in organisms of more than microscopic size there must frequently
+be minute, even microscopic differences which set going the process of
+selection, and regulate its progress to the highest possible perfection.
+
+Many tropical trees possess thick, leathery leaves, as a protection against
+the force of the tropical rain drops.  The DIRECT influence of the rain
+cannot be the cause of this power of resistance, for the leaves, while they
+were still thin, would simply have been torn to pieces.  Their toughness
+must therefore be referred to selection, which would favour the trees with
+slightly thicker leaves, though we cannot calculate with any exactness how
+great the first stages of increase in thickness must have been.  Our
+hypothesis receives further support from the fact that, in many such trees,
+the leaves are drawn out into a beak-like prolongation (Stahl and
+Haberlandt) which facilitates the rapid falling off of the rain water, and
+also from the fact that the leaves, while they are still young, hang limply
+down in bunches which offer the least possible resistance to the rain. 
+Thus there are here three adaptations which can only be interpreted as due
+to selection.  The initial stages of these adaptations must undoubtedly
+have had selection-value.
+
+But even in regard to this case we are reasoning in a circle, not giving
+"proofs," and no one who does not wish to believe in the selection-value of
+the initial stages can be forced to do so.  Among the many pieces of
+presumptive evidence a particularly weighty one seems to me to be THE
+SMALLNESS OF THE STEPS OF PROGRESS which we can observe in certain cases,
+as for instance in leaf-imitation among butterflies, and in mimicry
+generally.  The resemblance to a leaf, for instance of a particular
+Kallima, seems to us so close as to be deceptive, and yet we find in
+another individual, or it may be in many others, a spot added which
+increases the resemblance, and which could not have become fixed unless the
+increased deceptiveness so produced had frequently led to the overlooking
+of its much persecuted possessor.  But if we take the selection-value of
+the initial stages for granted, we are confronted with the further question
+which I myself formulated many years ago:  How does it happen THAT THE
+NECESSARY BEGINNINGS OF A USEFUL VARIATION ARE ALWAYS PRESENT?  How could
+insects which live upon or among green leaves become all green, while those
+that live on bark become brown?  How have the desert animals become yellow
+and the Arctic animals white?  Why were the necessary variations always
+present?  How could the green locust lay brown eggs, or the privet
+caterpillar develop white and lilac-coloured lines on its green skin?
+
+It is of no use answering to this that the question is wrongly formulated
+(Plate, "Selektionsprinzip u. Probleme der Artbildung" (3rd edition),
+Leipzig, 1908.) and that it is the converse that is true; that the process
+of selection takes place in accordance with the variations that present
+themselves.  This proposition is undeniably true, but so also is another,
+which apparently negatives it:  the variation required has in the majority
+of cases actually presented itself.  Selection cannot solve this
+contradiction; it does not call forth the useful variation, but simply
+works upon it.  The ultimate reason why one and the same insect should
+occur in green and in brown, as often happens in caterpillars and locusts,
+lies in the fact that variations towards brown presented themselves, and so
+also did variations towards green:  THE KERNEL OF THE RIDDLE LIES IN THE
+VARYING, and for the present we can only say, that small variations in
+different directions present themselves in every species.  Otherwise so
+many different kinds of variations could not have arisen.  I have
+endeavoured to explain this remarkable fact by means of the intimate
+processes that must take place within the germ-plasm, and I shall return to
+the problem when dealing with "germinal selection."
+
+We have, however, to make still greater demands on variation, for it is not
+enough that the necessary variation should occur in isolated individuals,
+because in that case there would be small prospect of its being preserved,
+notwithstanding its utility.  Darwin at first believed, that even single
+variations might lead to transformation of the species, but later he became
+convinced that this was impossible, at least without the cooperation of
+other factors, such as isolation and sexual selection.
+
+In the case of the GREEN CATERPILLARS WITH BRIGHT LONGITUDINAL STRIPES,
+numerous individuals exhibiting this useful variation must have been
+produced to start with.  In all higher, that is, multicellular organisms,
+the germ-substance is the source of all transmissible variations, and this
+germ-plasm is not a simple substance but is made up of many primary
+constituents.  The question can therefore be more precisely stated thus: 
+How does it come about that in so many cases the useful variations present
+themselves in numbers just where they are required, the white oblique lines
+in the leaf-caterpillar on the under surface of the body, the accompanying
+coloured stripes just above them?  And, further, how has it come about that
+in grass caterpillars, not oblique but longitudinal stripes, which are more
+effective for concealment among grass and plants, have been evolved?  And
+finally, how is it that the same Hawk-moth caterpillars, which to-day show
+oblique stripes, possessed longitudinal stripes in Tertiary times?  We can
+read this fact from the history of their development, and I have before
+attempted to show the biological significance of this change of colour. 
+("Studien zur Descendenz-Theorie" II., "Die Enstehung der Zeichnung bei den
+Schmetterlings-raupen," Leipzig, 1876.)
+
+For the present I need only draw the conclusion that one and the same
+caterpillar may exhibit the initial stages of both, and that it depends on
+the manner in which these marking elements are INTENSIFIED and COMBINED by
+natural selection whether whitish longitudinal or oblique stripes should
+result.  In this case then the "useful variations" were actually "always
+there," and we see that in the same group of Lepidoptera, e.g. species of
+Sphingidae, evolution has occurred in both directions according to whether
+the form lived among grass or on broad leaves with oblique lateral veins,
+and we can observe even now that the species with oblique stripes have
+longitudinal stripes when young, that is to say, while the stripes have no
+biological significance.  The white places in the skin which gave rise,
+probably first as small spots, to this protective marking could be combined
+in one way or another according to the requirements of the species.  They
+must therefore either have possessed selection-value from the first, or, if
+this was not the case at their earliest occurrence, there must have been
+SOME OTHER FACTORS which raised them to the point of selection-value.  I
+shall return to this in discussing germinal selection.  But the case may be
+followed still farther, and leads us to the same alternative on a still
+more secure basis.
+
+Many years ago I observed in caterpillars of Smerinthus populi (the poplar
+hawk-moth), which also possess white oblique stripes, that certain
+individuals showed RED SPOTS above these stripes; these spots occurred only
+on certain segments, and never flowed together to form continuous stripes.
+In another species (Smerinthus tiliae) similar blood-red spots unite to
+form a line-like coloured seam in the last stage of larval life, while in
+S. ocellata rust-red spots appear in individual caterpillars, but more
+rarely than in S. Populi, and they show no tendency to flow together.
+
+Thus we have here the origin of a new character, arising from small
+beginnings, at least in S. tiliae, in which species the coloured stripes
+are a normal specific character.  In the other species, S. populi and S.
+ocellata, we find the beginnings of the same variation, in one more rarely
+than in the other, and we can imagine that, in the course of time, in these
+two species, coloured lines over the oblique stripes will arise.  In any
+case these spots are the elements of variation, out of which coloured lines
+MAY be evolved, if they are combined in this direction through the agency
+of natural selection.  In S. populi the spots are often small, but
+sometimes it seems as though several had united to form large spots. 
+Whether a process of selection in this direction will arise in S. populi
+and S. ocellata, or whether it is now going on cannot be determined, since
+we cannot tell in advance what biological value the marking might have for
+these two species.  It is conceivable that the spots may have no selection-
+value as far as these species are concerned, and may therefore disappear
+again in the course of phylogeny, or, on the other hand, that they may be
+changed in another direction, for instance towards imitation of the rust-
+red fungoid patches on poplar and willow leaves.  In any case we may regard
+the smallest spots as the initial stages of variation, the larger as a
+cumulative summation of these.  Therefore either these initial stages must
+already possess selection-value, or, as I said before:  THERE MUST BE SOME
+OTHER REASON FOR THEIR CUMULATIVE SUMMATION.  I should like to give one
+more example, in which we can infer, though we cannot directly observe, the
+initial stages.
+
+All the Holothurians or sea-cucumbers have in the skin calcareous bodies of
+different forms, usually thick and irregular, which make the skin tough and
+resistant.  In a small group of them--the species of Synapta--the
+calcareous bodies occur in the form of delicate anchors of microscopic
+size.  Up till 1897 these anchors, like many other delicate microscopic
+structures, were regarded as curiosities, as natural marvels.  But a
+Swedish observer, Oestergren, has recently shown that they have a
+biological significance:  they serve the footless Synapta as auxiliary
+organs of locomotion, since, when the body swells up in the act of
+creeping, they press firmly with their tips, which are embedded in the
+skin, against the substratum on which the animal creeps, and thus prevent
+slipping backwards.  In other Holothurians this slipping is made impossible
+by the fixing of the tube-feet.  The anchors act automatically, sinking
+their tips towards the ground when the corresponding part of the body
+thickens, and returning to the original position at an angle of 45 degrees
+to the upper surface when the part becomes thin again.  The arms of the
+anchor do not lie in the same plane as the shaft, and thus the curve of the
+arms forms the outermost part of the anchor, and offers no further
+resistance to the gliding of the animal.  Every detail of the anchor, the
+curved portion, the little teeth at the head, the arms, etc., can be
+interpreted in the most beautiful way, above all the form of the anchor
+itself, for the two arms prevent it from swaying round to the side.  The
+position of the anchors, too, is definite and significant; they lie
+obliquely to the longitudinal axis of the animal, and therefore they act
+alike whether the animal is creeping backwards or forwards.  Moreover, the
+tips would pierce through the skin if the anchors lay in the longitudinal
+direction.  Synapta burrows in the sand; it first pushes in the thin
+anterior end, and thickens this again, thus enlarging the hole, then the
+anterior tentacles displace more sand, the body is worked in a little
+farther, and the process begins anew.  In the first act the anchors are
+passive, but they begin to take an active share in the forward movement
+when the body is contracted again.  Frequently the animal retains only the
+posterior end buried in the sand, and then the anchors keep it in position,
+and make rapid withdrawal possible.
+
+Thus we have in these apparently random forms of the calcareous bodies,
+complex adaptations in which every little detail as to direction, curve,
+and pointing is exactly determined.  That they have selection-value in
+their present perfected form is beyond all doubt, since the animals are
+enabled by means of them to bore rapidly into the ground and so to escape
+from enemies.  We do not know what the initial stages were, but we cannot
+doubt that the little improvements, which occurred as variations of the
+originally simple slimy bodies of the Holothurians, were preserved because
+they already possessed selection-value for the Synaptidae.  For such minute
+microscopic structures whose form is so delicately adapted to the role they
+have to play in the life of the animal, cannot have arisen suddenly and as
+a whole, and every new variation of the anchor, that is, in the direction
+of the development of the two arms, and every curving of the shaft which
+prevented the tips from projecting at the wrong time, in short, every
+little adaptation in the modelling of the anchor must have possessed
+selection-value.  And that such minute changes of form fall within the
+sphere of fluctuating variations, that is to say, THAT THEY OCCUR is beyond
+all doubt.
+
+In many of the Synaptidae the anchors are replaced by calcareous rods bent
+in the form of an S, which are said to act in the same way.  Others, such
+as those of the genus Ankyroderma, have anchors which project considerably
+beyond the skin, and, according to Oestergren, serve "to catch plant-
+particles and other substances" and so mask the animal.  Thus we see that
+in the Synaptidae the thick and irregular calcareous bodies of the
+Holothurians have been modified and transformed in various ways in
+adaptation to the footlessness of these animals, and to the peculiar
+conditions of their life, and we must conclude that the earlier stages of
+these changes presented themselves to the processes of selection in the
+form of microscopic variations.  For it is as impossible to think of any
+origin other than through selection in this case as in the case of the
+toughness, and the "drip-tips" of tropical leaves.  And as these last could
+not have been produced directly by the beating of the heavy rain-drops upon
+them, so the calcareous anchors of Synapta cannot have been produced
+directly by the friction of the sand and mud at the bottom of the sea, and,
+since they are parts whose function is PASSIVE the Lamarckian factor of use
+and disuse does not come into question.  The conclusion is unavoidable,
+that the microscopically small variations of the calcareous bodies in the
+ancestral forms have been intensified and accumulated in a particular
+direction, till they have led to the formation of the anchor.  Whether this
+has taken place by the action of natural selection alone, or whether the
+laws of variation and the intimate processes within the germ-plasm have
+cooperated will become clear in the discussion of germinal selection.  This
+whole process of adaptation has obviously taken place within the time that
+has elapsed since this group of sea-cucumbers lost their tube-feet, those
+characteristic organs of locomotion which occur in no group except the
+Echinoderms, and yet have totally disappeared in the Synaptidae.  And after
+all what would animals that live in sand and mud do with tube-feet?
+
+(c)  COADAPTATION.
+
+Darwin pointed out that one of the essential differences between artificial
+and natural selection lies in the fact that the former can modify only a
+few characters, usually only one at a time, while Nature preserves in the
+struggle for existence all the variations of a species, at the same time
+and in a purely mechanical way, if they possess selection-value.
+
+Herbert Spencer, though himself an adherent of the theory of selection,
+declared in the beginning of the nineties that in his opinion the range of
+this principle was greatly over-estimated, if the great changes which have
+taken place in so many organisms in the course of ages are to be
+interpreted as due to this process of selection alone, since no
+transformation of any importance can be evolved by itself; it is always
+accompanied by a host of secondary changes.  He gives the familiar example
+of the Giant Stag of the Irish peat, the enormous antlers of which required
+not only a much stronger skull cap, but also greater strength of the
+sinews, muscles, nerves and bones of the whole anterior half of the animal,
+if their mass was not to weigh down the animal altogether.  It is
+inconceivable, he says, that so many processes of selection should take
+place SIMULTANEOUSLY, and we are therefore forced to fall back on the
+Lamarckian factor of the use and disuse of functional parts.  And how, he
+asks, could natural selection follow two opposite directions of evolution
+in different parts of the body at the same time, as for instance in the
+case of the kangaroo, in which the forelegs must have become shorter, while
+the hind legs and the tail were becoming longer and stronger?
+
+Spencer's main object was to substantiate the validity of the Lamarckian
+principle, the cooperation of which with selection had been doubted by
+many.  And it does seem as though this principle, if it operates in nature
+at all, offers a ready and simple explanation of all such secondary
+variations.  Not only muscles, but nerves, bones, sinews, in short all
+tissues which function actively, increase in strength in proportion as they
+are used, and conversely they decrease when the claims on them diminish. 
+All the parts, therefore, which depend on the part that varied first, as
+for instance the enlarged antlers of the Irish Elk, must have been
+increased or decreased in strength, in exact proportion to the claims made
+upon them,--just as is actually the case.
+
+But beautiful as this explanation would be, I regard it as untenable,
+because it assumes the TRANSMISSIBILITY OF FUNCTIONAL MODIFICATIONS (so-
+called "acquired" characters), and this is not only undemonstrable, but is
+scarcely theoretically conceivable, for the secondary variations which
+accompany or follow the first as correlative variations, occur also in
+cases in which the animals concerned are sterile and THEREFORE CANNOT
+TRANSMIT ANYTHING TO THEIR DESCENDANTS.  This is true of WORKER BEES, and
+particularly of ANTS, and I shall here give a brief survey of the present
+state of the problem as it appears to me.
+
+Much has been written on both sides of this question since the published
+controversy on the subject in the nineties between Herbert Spencer and
+myself.  I should like to return to the matter in detail, if the space at
+my disposal permitted, because it seems to me that the arguments I advanced
+at that time are equally cogent to-day, notwithstanding all the objections
+that have since been urged against them.  Moreover, the matter is by no
+means one of subordinate interest; it is the very kernel of the whole
+question of the reality and value of the principle of selection.  For if
+selection alone does not suffice to explain "HARMONIOUS ADAPTATION" as I
+have called Spencer's COADAPTATION, and if we require to call in the aid of
+the Lamarckian factor it would be questionable whether selection could
+explain any adaptations whatever.  In this particular case--of worker bees
+--the Lamarckian factor may be excluded altogether, for it can be
+demonstrated that here at any rate the effects of use and disuse cannot be
+transmitted.
+
+But if it be asked why we are unwilling to admit the cooperation of the
+Darwinian factor of selection and the Lamarckian factor, since this would
+afford us an easy and satisfactory explanation of the phenomena, I answer: 
+BECAUSE THE LAMARCKIAN PRINCIPLE IS FALLACIOUS, AND BECAUSE BY ACCEPTING IT
+WE CLOSE THE WAY TOWARDS DEEPER INSIGHT.  It is not a spirit of
+combativeness or a desire for self-vindication that induces me to take the
+field once more against the Lamarckian principle, it is the conviction that
+the progress of our knowledge is being obstructed by the acceptance of this
+fallacious principle, since the facile explanation it apparently affords
+prevents our seeking after a truer explanation and a deeper analysis.
+
+The workers in the various species of ants are sterile, that is to say,
+they take no regular part in the reproduction of the species, although
+individuals among them may occasionally lay eggs.  In addition to this they
+have lost the wings, and the receptaculum seminis, and their compound eyes
+have degenerated to a few facets.  How could this last change have come
+about through disuse, since the eyes of workers are exposed to light in the
+same way as are those of the sexual insects and thus in this particular
+case are not liable to "disuse" at all?  The same is true of the
+receptaculum seminis, which can only have been disused as far as its
+glandular portion and its stalk are concerned, and also of the wings, the
+nerves tracheae and epidermal cells of which could not cease to function
+until the whole wing had degenerated, for the chitinous skeleton of the
+wing does not function at all in the active sense.
+
+But, on the other hand, the workers in all species have undergone
+modifications in a positive direction, as, for instance, the greater
+development of brain.  In many species large workers have evolved,--the so-
+called SOLDIERS, with enormous jaws and teeth, which defend the colony,--
+and in others there are SMALL workers which have taken over other special
+functions, such as the rearing of the young Aphides.  This kind of division
+of the workers into two castes occurs among several tropical species of
+ants, but it is also present in the Italian species, Colobopsis truncata. 
+Beautifully as the size of the jaws could be explained as due to the
+increased use made of them by the "soldiers," or the enlarged brain as due
+to the mental activities of the workers, the fact of the infertility of
+these forms is an insurmountable obstacle to accepting such an explanation.
+Neither jaws nor brain can have been evolved on the Lamarckian principle.
+
+The problem of coadaptation is no easier in the case of the ant than in the
+case of the Giant Stag.  Darwin himself gave a pretty illustration to show
+how imposing the difference between the two kinds of workers in one species
+would seem if we translated it into human terms.  In regard to the Driver
+ants (Anomma) we must picture to ourselves a piece of work, "for instance
+the building of a house, being carried on by two kinds of workers, of which
+one group was five feet four inches high, the other sixteen feet high." 
+("Origin of Species" (6th edition), page 232.)
+
+Although the ant is a small animal as compared with man or with the Irish
+Elk, the "soldier" with its relatively enormous jaws is hardly less heavily
+burdened than the Elk with its antlers, and in the ant's case, too, a
+strengthening of the skeleton, of the muscles, the nerves of the head, and
+of the legs must have taken place parallel with the enlargement of the
+jaws.  HARMONIOUS ADAPTATION (coadaptation) has here been active in a high
+degree, and yet these "soldiers" are sterile!  There thus remains nothing
+for it but to refer all their adaptations, positive and negative alike, to
+processes of selection which have taken place in the rudiments of the
+workers within the egg and sperm-cells of their parents.  There is no way
+out of the difficulty except the one Darwin pointed out.  He himself did
+not find the solution of the riddle at once.  At first he believed that the
+case of the workers among social insects presented "the most serious
+special difficulty" in the way of his theory of natural selection; and it
+was only after it had become clear to him, that it was not the sterile
+insects themselves but their parents that were selected, according as they
+produced more or less well adapted workers, that he was able to refer to
+this very case of the conditions among ants "IN ORDER TO SHOW THE POWER OF
+NATURAL SELECTION" ("Origin of Species", page 233; see also edition 1, page
+242.).  He explains his view by a simple but interesting illustration. 
+Gardeners have produced, by means of long continued artificial selection, a
+variety of Stock, which bears entirely double, and therefore infertile
+flowers (Ibid. page 230.).  Nevertheless the variety continues to be
+reproduced from seed, because in addition to the double and infertile
+flowers, the seeds always produce a certain number of single, fertile
+blossoms, and these are used to reproduce the double variety.  These single
+and fertile plants correspond "to the males and females of an ant-colony,
+the infertile plants, which are regularly produced in large numbers, to the
+neuter workers of the colony."
+
+This illustration is entirely apt, the only difference between the two
+cases consisting in the fact that the variation in the flower is not a
+useful, but a disadvantageous one, which can only be preserved by
+artificial selection on the part of the gardener, while the transformations
+that have taken place parallel with the sterility of the ants are useful,
+since they procure for the colony an advantage in the struggle for
+existence, and they are therefore preserved by natural selection.  Even the
+sterility itself in this case is not disadvantageous, since the fertility
+of the true females has at the same time considerably increased.  We may
+therefore regard the sterile forms of ants, which have gradually been
+adapted in several directions to varying functions, AS A CERTAIN PROOF that
+selection really takes place in the germ-cells of the fathers and mothers
+of the workers, and that SPECIAL COMPLEXES OF PRIMORDIA (IDS) are present
+in the workers and in the males and females, and these complexes contain
+the primordia of the individual parts (DETERMINANTS).  But since all living
+entities vary, the determinants must also vary, now in a favourable, now in
+an unfavourable direction.  If a female produces eggs, which contain
+favourably varying determinants in the worker-ids, then these eggs will
+give rise to workers modified in the favourable direction, and if this
+happens with many females, the colony concerned will contain a better kind
+of worker than other colonies.
+
+I digress here in order to give an account of the intimate processes,
+which, according to my view, take place within the germ-plasm, and which I
+have called "GERMINAL SELECTION."  These processes are of importance since
+they form the roots of variation, which in its turn is the root of natural
+selection.  I cannot here do more than give a brief outline of the theory
+in order to show how the Darwin-Wallace theory of selection has gained
+support from it.
+
+With others, I regard the minimal amount of substance which is contained
+within the nucleus of the germ-cells, in the form of rods, bands, or
+granules, as the GERM-SUBSTANCE or GERM-PLASM, and I call the individual
+granules IDS.  There is always a multiplicity of such ids present in the
+nucleus, either occurring individually, or united in the form of rods or
+bands (chromosomes).  Each id contains the primary constituents of a WHOLE
+individual, so that several ids are concerned in the development of a new
+individual.
+
+In every being of complex structure thousands of primary constituents must
+go to make up a single id; these I call DETERMINANTS, and I mean by this
+name very small individual particles, far below the limits of microscopic
+visibility, vital units which feed, grow, and multiply by division.  These
+determinants control the parts of the developing embryo,--in what manner
+need not here concern us.  The determinants differ among themselves, those
+of a muscle are differently constituted from those of a nerve-cell or a
+glandular cell, etc., and every determinant is in its turn made up of
+minute vital units, which I call BIOPHORS, or the bearers of life. 
+According to my view, these determinants not only assimilate, like every
+other living unit, but they VARY in the course of their growth, as every
+living unit does; they may vary qualitatively if the elements of which they
+are composed vary, they may grow and divide more or less rapidly, and their
+variations give rise to CORRESPONDING variations of the organ, cell, or
+cell-group which they determine.  That they are undergoing ceaseless
+fluctuations in regard to size and quality seems to me the inevitable
+consequence of their unequal nutrition; for although the germ-cell as a
+whole usually receives sufficient nutriment, minute fluctuations in the
+amount carried to different parts within the germ-plasm cannot fail to
+occur.
+
+Now, if a determinant, for instance of a sensory cell, receives for a
+considerable time more abundant nutriment than before, it will grow more
+rapidly--become bigger, and divide more quickly, and, later, when the id
+concerned develops into an embryo, this sensory cell will become stronger
+than in the parents, possibly even twice as strong.  This is an instance of
+a HEREDITARY INDIVIDUAL VARIATION, arising from the germ.
+
+The nutritive stream which, according to our hypothesis, favours the
+determinant N by chance, that is, for reasons unknown to us, may remain
+strong for a considerable time, or may decrease again; but even in the
+latter case it is conceivable that the ascending movement of the
+determinant may continue, because the strengthened determinant now ACTIVELY
+nourishes itself more abundantly,--that is to say, it attracts the
+nutriment to itself, and to a certain extent withdraws it from its fellow-
+determinants.  In this way, it may--as it seems to me--get into PERMANENT
+UPWARD MOVEMENT, AND ATTAIN A DEGREE OF STRENGTH FROM WHICH THERE IS NO
+FALLING BACK.  Then positive or negative selection sets in, favouring the
+variations which are advantageous, setting aside those which are
+disadvantageous.
+
+In a similar manner a DOWNWARD variation of the determinants may take
+place, if its progress be started by a diminished flow of nutriment.  The
+determinants which are weakened by this diminished flow will have less
+affinity for attracting nutriment because of their diminished strength, and
+they will assimilate more feebly and grow more slowly, unless chance
+streams of nutriment help them to recover themselves.  But, as will
+presently be shown, a change of direction cannot take place at EVERY stage
+of the degenerative process.  If a certain critical stage of downward
+progress be passed, even favourable conditions of food-supply will no
+longer suffice permanently to change the direction of the variation.  Only
+two cases are conceivable; if the determinant corresponds to a USEFUL
+organ, only its removal can bring back the germ-plasm to its former level;
+therefore personal selection removes the id in question, with its
+determinants, from the germ-plasm, by causing the elimination of the
+individual in the struggle for existence.  But there is another conceivable
+case; the determinants concerned may be those of an organ which has become
+USELESS, and they will then continue unobstructed, but with exceeding
+slowness, along the downward path, until the organ becomes vestigial, and
+finally disappears altogether.
+
+The fluctuations of the determinants hither and thither may thus be
+transformed into a lasting ascending or descending movement; and THIS IS
+THE CRUCIAL POINT OF THESE GERMINAL PROCESSES.
+
+This is not a fantastic assumption; we can read it in the fact of the
+degeneration of disused parts.  USELESS ORGANS ARE THE ONLY ONES WHICH ARE
+NOT HELPED TO ASCEND AGAIN BY PERSONAL SELECTION, AND THEREFORE IN THEIR
+CASE ALONE CAN WE FORM ANY IDEA OF HOW THE PRIMARY CONSTITUENTS BEHAVE,
+WHEN THEY ARE SUBJECT SOLELY TO INTRA-GERMINAL FORCES.
+
+The whole determinant system of an id, as I conceive it, is in a state of
+continual fluctuation upwards and downwards.  In most cases the
+fluctuations will counteract one another, because the passive streams of
+nutriment soon change, but in many cases the limit from which a return is
+possible will be passed, and then the determinants concerned will continue
+to vary in the same direction, till they attain positive or negative
+selection-value.  At this stage personal selection intervenes and sets
+aside the variation if it is disadvantageous, or favours--that is to say,
+preserves--it if it is advantageous.  Only THE DETERMINANT OF A USELESS
+ORGAN IS UNINFLUENCED BY PERSONAL SELECTION, and, as experience shows, it
+sinks downwards; that is, the organ that corresponds to it degenerates very
+slowly but uninterruptedly till, after what must obviously be an immense
+stretch of time, it disappears from the germ-plasm altogether.
+
+Thus we find in the fact of the degeneration of disused parts the proof
+that not all the fluctuations of a determinant return to equilibrium again,
+but that, when the movement has attained to a certain strength, it
+continues IN THE SAME DIRECTION.  We have entire certainty in regard to
+this as far as the downward progress is concerned, and we must assume it
+also in regard to ascending variations, as the phenomena of artificial
+selection certainly justify us in doing.  If the Japanese breeders were
+able to lengthen the tail feathers of the cock to six feet, it can only
+have been because the determinants of the tail-feathers in the germ-plasm
+had already struck out a path of ascending variation, and this movement was
+taken advantage of by the breeder, who continually selected for
+reproduction the individuals in which the ascending variation was most
+marked.  For all breeding depends upon the unconscious selection of
+germinal variations.
+
+Of course these germinal processes cannot be proved mathematically, since
+we cannot actually see the play of forces of the passive fluctuations and
+their causes.  We cannot say how great these fluctuations are, and how
+quickly or slowly, how regularly or irregularly they change.  Nor do we
+know how far a determinant must be strengthened by the passive flow of the
+nutritive stream if it is to be beyond the danger of unfavourable
+variations, or how far it must be weakened passively before it loses the
+power of recovering itself by its own strength.  It is no more possible to
+bring forward actual proofs in this case than it was in regard to the
+selection-value of the initial stages of an adaptation.  But if we consider
+that all heritable variations must have their roots in the germ-plasm, and
+further, that when personal selection does not intervene, that is to say,
+in the case of parts which have become useless, a degeneration of the part,
+and therefore also of its determinant must inevitably take place; then we
+must conclude that processes such as I have assumed are running their
+course within the germ-plasm, and we can do this with as much certainty as
+we were able to infer, from the phenomena of adaptation, the selection-
+value of their initial stages.  The fact of the degeneration of disused
+parts seems to me to afford irrefutable proof that the fluctuations within
+the germ-plasm ARE THE REAL ROOT OF ALL HEREDITARY VARIATION, and the
+preliminary condition for the occurrence of the Darwin-Wallace factor of
+selection.  Germinal selection supplies the stones out of which personal
+selection builds her temples and palaces:  ADAPTATIONS.  The importance for
+the theory of the process of degeneration of disused parts cannot be over-
+estimated, especially when it occurs in sterile animal forms, where we are
+free from the doubt as to the alleged LAMARCKIAN FACTOR which is apt to
+confuse our ideas in regard to other cases.
+
+If we regard the variation of the many determinants concerned in the
+transformation of the female into the sterile worker as having come about
+through the gradual transformation of the ids into worker-ids, we shall see
+that the germ-plasm of the sexual ants must contain three kinds of ids,
+male, female, and worker ids, or if the workers have diverged into soldiers
+and nest-builders, then four kinds.  We understand that the worker-ids
+arose because their determinants struck out a useful path of variation,
+whether upward or downward, and that they continued in this path until the
+highest attainable degree of utility of the parts determined was reached. 
+But in addition to the organs of positive or negative selection-value,
+there were some which were indifferent as far as the success and especially
+the functional capacity of the workers was concerned:  wings, ovarian
+tubes, receptaculum seminis, a number of the facets of the eye, perhaps
+even the whole eye.  As to the ovarian tubes it is possible that their
+degeneration was an advantage for the workers, in saving energy, and if so
+selection would favour the degeneration; but how could the presence of eyes
+diminish the usefulness of the workers to the colony? or the minute
+receptaculum seminis, or even the wings?  These parts have therefore
+degenerated BECAUSE THEY WERE OF NO FURTHER VALUE TO THE INSECT.  But if
+selection did not influence the setting aside of these parts because they
+were neither of advantage nor of disadvantage to the species, then the
+Darwinian factor of selection is here confronted with a puzzle which it
+cannot solve alone, but which at once becomes clear when germinal selection
+is added.  For the determinants of organs that have no further value for
+the organism, must, as we have already explained, embark on a gradual
+course of retrograde development.
+
+In ants the degeneration has gone so far that there are no wing-rudiments
+present in ANY species, as is the case with so many butterflies, flies, and
+locusts, but in the larvae the imaginal discs of the wings are still laid
+down.  With regard to the ovaries, degeneration has reached different
+levels in different species of ants, as has been shown by the researches of
+my former pupil, Elizabeth Bickford.  In many species there are twelve
+ovarian tubes, and they decrease from that number to one; indeed, in one
+species no ovarian tube at all is present.  So much at least is certain
+from what has been said, that in this case EVERYTHING depends on the
+fluctuations of the elements of the germ-plasm.  Germinal selection, here
+as elsewhere, presents the variations of the determinants, and personal
+selection favours or rejects these, or,--if it be a question of organs
+which have become useless,--it does not come into play at all, and allows
+the descending variation free course.
+
+It is obvious that even the problem of COADAPTATION IN STERILE ANIMALS can
+thus be satisfactorily explained.  If the determinants are oscillating
+upwards and downwards in continual fluctuation, and varying more
+pronouncedly now in one direction now in the other, useful variations of
+every determinant will continually present themselves anew, and may, in the
+course of generations, be combined with one another in various ways.  But
+there is one character of the determinants that greatly facilitates this
+complex process of selection, that, after a certain limit has been reached,
+they go on varying in the same direction.  From this it follows that
+development along a path once struck out may proceed without the continual
+intervention of personal selection.  This factor only operates, so to
+speak, at the beginning, when it selects the determinants which are varying
+in the right direction, and again at the end, when it is necessary to put a
+check upon further variation.  In addition to this, enormously long periods
+have been available for all these adaptations, as the very gradual
+transition stages between females and workers in many species plainly show,
+and thus this process of transformation loses the marvellous and mysterious
+character that seemed at the first glance to invest it, and takes rank,
+without any straining, among the other processes of selection.  It seems to
+me that, from the facts that sterile animal forms can adapt themselves to
+new vital functions, their superfluous parts degenerate, and the parts more
+used adapt themselves in an ascending direction, those less used in a
+descending direction, we must draw the conclusion that harmonious
+adaptation here comes about WITHOUT THE COOPERATION OF THE LAMARCKIAN
+PRINCIPLE.  This conclusion once established, however, we have no reason to
+refer the thousands of cases of harmonious adaptation, which occur in
+exactly the same way among other animals or plants, to a principle, the
+ACTIVE INTERVENTION OF WHICH IN THE TRANSFORMATION OF SPECIES IS NOWHERE
+PROVED.  WE DO NOT REQUIRE IT TO EXPLAIN THE FACTS, AND THEREFORE WE MUST
+NOT ASSUME IT.
+
+The fact of coadaptation, which was supposed to furnish the strongest
+argument against the principle of selection, in reality yields the clearest
+evidence in favour of it.  We MUST assume it, BECAUSE NO OTHER POSSIBILITY
+OF EXPLANATION IS OPEN TO US, AND BECAUSE THESE ADAPTATIONS ACTUALLY EXIST,
+THAT IS TO SAY, HAVE REALLY TAKEN PLACE.  With this conviction I attempted,
+as far back as 1894, when the idea of germinal selection had not yet
+occurred to me, to make "harmonious adaptation" (coadaptation) more easily
+intelligible in some way or other, and so I was led to the idea, which was
+subsequently expounded in detail by Baldwin, and Lloyd Morgan, and also by
+Osborn, and Gulick as ORGANIC SELECTION.  It seemed to me that it was not
+necessary that all the germinal variations required for secondary
+variations should have occurred SIMULTANEOUSLY, since, for instance, in the
+case of the stag, the bones, muscles, sinews, and nerves would be incited
+by the increasing heaviness of the antlers to greater activity in THE
+INDIVIDUAL LIFE, and so would be strengthened.  The antlers can only have
+increased in size by very slow degrees, so that the muscles and bones may
+have been able to keep pace with their growth in the individual life, until
+the requisite germinal variations presented themselves.  In this way a
+disharmony between the increasing weight of the antlers and the parts which
+support and move them would be avoided, since time would be given for the
+appropriate germinal variations to occur, and so to set agoing the
+HEREDITARY variation of the muscles, sinews, and bones.  ("The Effect of
+External Influences upon Development", Romanes Lecture, Oxford, 1894.)
+
+I still regard this idea as correct, but I attribute less importance to
+"organic selection" than I did at that time, in so far that I do not
+believe that it ALONE could effect complex harmonious adaptations. 
+Germinal selection now seems to me to play the chief part in bringing about
+such adaptations.  Something the same is true of the principle I have
+called "Panmixia".  As I became more and more convinced, in the course of
+years, that the LAMARCKIAN PRINCIPLE ought not to be called in to explain
+the dwindling of disused parts, I believed that this process might be
+simply explained as due to the cessation of the conservative effect of
+natural selection.  I said to myself that, from the moment in which a part
+ceases to be of use, natural selection withdraws its hand from it, and then
+it must inevitably fall from the height of its adaptiveness, because
+inferior variants would have as good a chance of persisting as better ones,
+since all grades of fitness of the part in question would be mingled with
+one another indiscriminately.  This is undoubtedly true, as Romanes pointed
+out ten years before I did, and this mingling of the bad with the good
+probably does bring about a deterioration of the part concerned.  But it
+cannot account for the steady diminution, which always occurs when a part
+is in process of becoming rudimentary, and which goes on until it
+ultimately disappears altogether.  The process of dwindling cannot
+therefore be explained as due to panmixia alone; we can only find a
+sufficient explanation in germinal selection.
+
+IV.  DERIVATIVES OF THE THEORY OF SELECTION.
+
+The impetus in all directions given by Darwin through his theory of
+selection has been an immeasurable one, and its influence is still felt. It
+falls within the province of the historian of science to enumerate all the
+ideas which, in the last quarter of the nineteenth century, grew out of
+Darwin's theories, in the endeavour to penetrate more deeply into the
+problem of the evolution of the organic world.  Within the narrow limits to
+which this paper is restricted, I cannot attempt to discuss any of these.
+
+V.  ARGUMENTS FOR THE REALITY OF THE PROCESSES OF SELECTION.
+
+(a)  SEXUAL SELECTION.
+
+Sexual selection goes hand in hand with natural selection.  From the very
+first I have regarded sexual selection as affording an extremely important
+and interesting corroboration of natural selection, but, singularly enough,
+it is precisely against this theory that an adverse judgment has been
+pronounced in so many quarters, and it is only quite recently, and probably
+in proportion as the wealth of facts in proof of it penetrates into a wider
+circle, that we seem to be approaching a more general recognition of this
+side of the problem of adaptation.  Thus Darwin's words in his preface to
+the second edition (1874) of his book, "The Descent of Man and Sexual
+Selection", are being justified:  "My conviction as to the operation of
+natural selection remains unshaken," and further, "If naturalists were to
+become more familiar with the idea of sexual selection, it would, I think,
+be accepted to a much greater extent, and already it is fully and
+favourably accepted by many competent judges."  Darwin was able to speak
+thus because he was already acquainted with an immense mass of facts,
+which, taken together, yield overwhelming evidence of the validity of the
+principle of sexual selection.
+
+NATURAL SELECTION chooses out for reproduction the individuals that are
+best equipped for the struggle for existence, and it does so at every stage
+of development; it thus improves the species in all its stages and forms. 
+SEXUAL SELECTION operates only on individuals that are already capable of
+reproduction, and does so only in relation to the attainment of
+reproduction.  It arises from the rivalry of one sex, usually the male, for
+the possession of the other, usually the female.  Its influence can
+therefore only DIRECTLY affect one sex, in that it equips it better for
+attaining possession of the other.  But the effect may extend indirectly to
+the female sex, and thus the whole species may be modified, without,
+however, becoming any more capable of resistance in the struggle for
+existence, for sexual selection only gives rise to adaptations which are
+likely to give their possessor the victory over rivals in the struggle for
+possession of the female, and which are therefore peculiar to the wooing
+sex:  the manifold "secondary sexual characters."  The diversity of these
+characters is so great that I cannot here attempt to give anything
+approaching a complete treatment of them, but I should like to give a
+sufficient number of examples to make the principle itself, in its various
+modes of expression, quite clear.
+
+One of the chief preliminary postulates of sexual selection is the unequal
+number of individuals in the two sexes, for if every male immediately finds
+his mate there can be no competition for the possession of the female. 
+Darwin has shown that, for the most part, the inequality between the sexes
+is due simply to the fact that there are more males than females, and
+therefore the males must take some pains to secure a mate.  But the
+inequality does not always depend on the numerical preponderance of the
+males, it is often due to polygamy; for, if one male claims several
+females, the number of females in proportion to the rest of the males will
+be reduced.  Since it is almost always the males that are the wooers, we
+must expect to find the occurrence of secondary sexual characters chiefly
+among them, and to find it especially frequent in polygamous species.  And
+this is actually the case.
+
+If we were to try to guess--without knowing the facts--what means the male
+animals make use of to overcome their rivals in the struggle for the
+possession of the female, we might name many kinds of means, but it would
+be difficult to suggest any which is not actually employed in some animal
+group or other.  I begin with the mere difference in strength, through
+which the male of many animals is so sharply distinguished from the female,
+as, for instance, the lion, walrus, "sea-elephant," and others.  Among
+these the males fight violently for the possession of the female, who falls
+to the victor in the combat.  In this simple case no one can doubt the
+operation of selection, and there is just as little room for doubt as to
+the selection-value of the initial stages of the variation.  Differences in
+bodily strength are apparent even among human beings, although in their
+case the struggle for the possession of the female is no longer decided by
+bodily strength alone.
+
+Combats between male animals are often violent and obstinate, and the
+employment of the natural weapons of the species in this way has led to
+perfecting of these, e.g. the tusks of the boar, the antlers of the stag,
+and the enormous, antler-like jaws of the stag-beetle.  Here again it is
+impossible to doubt that variations in these organs presented themselves,
+and that these were considerable enough to be decisive in combat, and so to
+lead to the improvement of the weapon.
+
+Among many animals, however, the females at first withdraw from the males;
+they are coy, and have to be sought out, and sometimes held by force.  This
+tracking and grasping of the females by the males has given rise to many
+different characters in the latter, as, for instance, the larger eyes of
+the male bee, and especially of the males of the Ephemerids (May-flies),
+some species of which show, in addition to the usual compound eyes, large,
+so-called turban-eyes, so that the whole head is covered with seeing
+surfaces. In these species the females are very greatly in the minority (1-
+100), and it is easy to understand that a keen competition for them must
+take place, and that, when the insects of both sexes are floating freely in
+the air, an unusually wide range of vision will carry with it a decided
+advantage.  Here again the actual adaptations are in accordance with the
+preliminary postulates of the theory.  We do not know the stages through
+which the eye has passed to its present perfected state, but, since the
+number of simple eyes (facets) has become very much greater in the male
+than in the female, we may assume that their increase is due to a gradual
+duplication of the determinants of the ommatidium in the germ-plasm, as I
+have already indicated in regard to sense-organs in general.  In this case,
+again, the selection-value of the initial stages hardly admits of doubt;
+better vision DIRECTLY secures reproduction.
+
+In many cases THE ORGAN OF SMELL shows a similar improvement.  Many lower
+Crustaceans (Daphnidae) have better developed organs of smell in the male
+sex.  The difference is often slight and amounts only to one or two
+olfactory filaments, but certain species show a difference of nearly a
+hundred of these filaments (Leptodora).  The same thing occurs among
+insects.
+
+We must briefly consider the clasping or grasping organs which have
+developed in the males among many lower Crustaceans, but here natural
+selection plays its part along with sexual selection, for the union of the
+sexes is an indispensable condition for the maintenance of the species, and
+as Darwin himself pointed out, in many cases the two forms of selection
+merge into each other.  This fact has always seemed to me to be a proof of
+natural selection, for, in regard to sexual selection, it is quite obvious
+that the victory of the best-equipped could have brought about the
+improvement only of the organs concerned, the factors in the struggle, such
+as the eye and the olfactory organ.
+
+We come now to the EXCITANTS; that is, to the group of sexual characters
+whose origin through processes of selection has been most frequently called
+in question.  We may cite the LOVE-CALLS produced by many male insects,
+such as crickets and cicadas.  These could only have arisen in animal
+groups in which the female did not rapidly flee from the male, but was
+inclined to accept his wooing from the first.  Thus, notes like the
+chirping of the male cricket serve to entice the females.  At first they
+were merely the signal which showed the presence of a male in the
+neighbourhood, and the female was gradually enticed nearer and nearer by
+the continued chirping.  The male that could make himself heard to the
+greatest distance would obtain the largest following, and would transmit
+the beginnings, and, later, the improvement of his voice to the greatest
+number of descendants.  But sexual excitement in the female became
+associated with the hearing of the love-call, and then the sound-producing
+organ of the male began to improve, until it attained to the emission of
+the long-drawn-out soft notes of the mole-cricket or the maenad-like cry of
+the cicadas.  I cannot here follow the process of development in detail,
+but will call attention to the fact that the original purpose of the voice,
+the announcing of the male's presence, became subsidiary, and the exciting
+of the female became the chief goal to be aimed at.  The loudest singers
+awakened the strongest excitement, and the improvement resulted as a matter
+of course.  I conceive of the origin of bird-song in a somewhat similar
+manner, first as a means of enticing, then of exciting the female.
+
+One more kind of secondary sexual character must here be mentioned:  the
+odour which emanates from so many animals at the breeding season.  It is
+possible that this odour also served at first merely to give notice of the
+presence of individuals of the other sex, but it soon became an excitant,
+and as the individuals which caused the greatest degree of excitement were
+preferred, it reached as high a pitch of perfection as was possible to it. 
+I shall confine myself here to the comparatively recently discovered
+fragrance of butterflies.  Since Fritz Muller found out that certain
+Brazilian butterflies gave off fragrance "like a flower," we have become
+acquainted with many such cases, and we now know that in all lands, not
+only many diurnal Lepidoptera but nocturnal ones also give off a delicate
+odour, which is agreeable even to man.  The ethereal oil to which this
+fragrance is due is secreted by the skin-cells, usually of the wing, as I
+showed soon after the discovery of the SCENT-SCALES.  This is the case in
+the males; the females have no SPECIAL scent-scales recognisable as such by
+their form, but they must, nevertheless, give off an extremely delicate
+fragrance, although our imperfect organ of smell cannot perceive it, for
+the males become aware of the presence of a female, even at night, from a
+long distance off, and gather round her.  We may therefore conclude, that
+both sexes have long given forth a very delicate perfume, which announced
+their presence to others of the same species, and that in many species (NOT
+IN ALL) these small beginnings became, in the males, particularly strong
+scent-scales of characteristic form (lute, brush, or lyre-shaped).  At
+first these scales were scattered over the surface of the wing, but
+gradually they concentrated themselves, and formed broad, velvety bands, or
+strong, prominent brushes, and they attained their highest pitch of
+evolution when they became enclosed within pits or folds of the skin, which
+could be opened to let the delicious fragrance stream forth suddenly
+towards the female.  Thus in this case also we see that characters, the
+original use of which was to bring the sexes together, and so to maintain
+the species, have been evolved in the males into means for exciting the
+female.  And we can hardly doubt, that the females are most readily enticed
+to yield to the butterfly that sends out the strongest fragrance,--that is
+to say, that excites them to the highest degree.  It is a pity that our
+organs of smell are not fine enough to examine the fragrance of male
+Lepidoptera in general, and to compare it with other perfumes which attract
+these insects.  (See Poulton, "Essays on Evolution", 1908, pages 316, 317.) 
+As far as we can perceive them they resemble the fragrance of flowers, but
+there are Lepidoptera whose scent suggests musk.  A smell of musk is also
+given off by several plants:  it is a sexual excitant in the musk-deer, the
+musk-sheep, and the crocodile.
+
+As far as we know, then, it is perfumes similar to those of flowers that
+the male Lepidoptera give off in order to entice their mates, and this is a
+further indication that animals, like plants, can to a large extent meet
+the claims made upon them by life, and produce the adaptations which are
+most purposive,--a further proof, too, of my proposition that the useful
+variations, so to speak, are ALWAYS THERE.  The flowers developed the
+perfumes which entice their visitors, and the male Lepidoptera developed
+the perfumes which entice and excite their mates.
+
+There are many pretty little problems to be solved in this connection, for
+there are insects, such as some flies, that are attracted by smells which
+are unpleasant to us, like those from decaying flesh and carrion.  But
+there are also certain flowers, some orchids for instance, which give forth
+no very agreeable odour, but one which is to us repulsive and disgusting;
+and we should therefore expect that the males of such insects would give
+off a smell unpleasant to us, but there is no case known to me in which
+this has been demonstrated.
+
+In cases such as we have discussed, it is obvious that there is no possible
+explanation except through selection.  This brings us to the last kind of
+secondary sexual characters, and the one in regard to which doubt has been
+most frequently expressed,--decorative colours and decorative forms, the
+brilliant plumage of the male pheasant, the humming-birds, and the bird of
+Paradise, as well as the bright colours of many species of butterfly, from
+the beautiful blue of our little Lycaenidae to the magnificent azure of the
+large Morphinae of Brazil.  In a great many cases, though not by any means
+in all, the male butterflies are "more beautiful" than the females, and in
+the Tropics in particular they shine and glow in the most superb colours. 
+I really see no reason why we should doubt the power of sexual selection,
+and I myself stand wholly on Darwin's side.  Even though we certainly
+cannot assume that the females exercise a conscious choice of the
+"handsomest" mate, and deliberate like the judges in a court of justice
+over the perfections of their wooers, we have no reason to doubt that
+distinctive forms (decorative feathers) and colours have a particularly
+exciting effect upon the female, just as certain odours have among animals
+of so many different groups, including the butterflies.  The doubts which
+existed for a considerable time, as a result of fallacious experiments, as
+to whether the colours of flowers really had any influence in attracting
+butterflies have now been set at rest through a series of more careful
+investigations; we now know that the colours of flowers are there on
+account of the butterflies, as Sprengel first showed, and that the blossoms
+of Phanerogams are selected in relation to them, as Darwin pointed out.
+
+Certainly it is not possible to bring forward any convincing proof of the
+origin of decorative colours through sexual selection, but there are many
+weighty arguments in favour of it, and these form a body of presumptive
+evidence so strong that it almost amounts to certainty.
+
+In the first place, there is the analogy with other secondary sexual
+characters. If the song of birds and the chirping of the cricket have been
+evolved through sexual selection, if the penetrating odours of male
+animals,--the crocodile, the musk-deer, the beaver, the carnivores, and,
+finally, the flower-like fragrances of the butterflies have been evolved to
+their present pitch in this way, why should decorative colours have arisen
+in some other way?  Why should the eye be less sensitive to SPECIFICALLY
+MALE colours and other VISIBLE signs ENTICING TO THE FEMALE, than the
+olfactory sense to specifically male odours, or the sense of hearing to
+specifically male sounds?  Moreover, the decorative feathers of birds are
+almost always spread out and displayed before the female during courtship. 
+I have elsewhere ("The Evolution Theory", London, 1904, I. page 219.)
+pointed out that decorative colouring and sweet-scentedness may replace one
+another in Lepidoptera as well as in flowers, for just as some modestly
+coloured flowers (mignonette and violet) have often a strong perfume, while
+strikingly coloured ones are sometimes quite devoid of fragrance, so we
+find that the most beautiful and gaily-coloured of our native Lepidoptera,
+the species of Vanessa, have no scent-scales, while these are often
+markedly developed in grey nocturnal Lepidoptera.  Both attractions may,
+however, be combined in butterflies, just as in flowers.  Of course, we
+cannot explain why both means of attraction should exist in one genus, and
+only one of them in another, since we do not know the minutest details of
+the conditions of life of the genera concerned.  But from the sporadic
+distribution of scent-scales in Lepidoptera, and from their occurrence or
+absence in nearly related species, we may conclude that fragrance is a
+relatively MODERN acquirement,  more recent than brilliant colouring.
+
+One thing in particular that stamps decorative colouring as a product of
+selection is ITS GRADUAL INTENSIFICATION by the addition of new spots,
+which we can quite well observe, because in many cases the colours have
+been first acquired by the males, and later transmitted to the females by
+inheritance.  The scent-scales are never thus transmitted, probably for the
+same reason that the decorative colours of many birds are often not
+transmitted to the females:  because with these they would be exposed to
+too great elimination by enemies.  Wallace was the first to point out that
+in species with concealed nests the beautiful feathers of the male occurred
+in the female also, as in the parrots, for instance, but this is not the
+case in species which brood on an exposed nest.  In the parrots one can
+often observe that the general brilliant colouring of the male is found in
+the female, but that certain spots of colour are absent, and these have
+probably been acquired comparatively recently by the male and have not yet
+been transmitted to the female.
+
+Isolation of the group of individuals which is in process of varying is
+undoubtedly of great value in sexual selection, for even a solitary
+conspicuous variation will become dominant much sooner in a small isolated
+colony, than among a large number of members of a species.
+
+Anyone who agrees with me in deriving variations from germinal selection
+will regard that process as an essential aid towards explaining the
+selection of distinctive courtship-characters, such as coloured spots,
+decorative feathers, horny outgrowths in birds and reptiles, combs,
+feather-tufts, and the like, since the beginnings of these would be
+presented with relative frequency in the struggle between the determinants
+within the germ-plasm.  The process of transmission of decorative feathers
+to the female results, as Darwin pointed out and illustrated by interesting
+examples, in the COLOUR-TRANSFORMATION OF A WHOLE SPECIES, and this
+process, as the phyletically older colouring of young birds shows, must, in
+the course of thousands of years, have repeated itself several times in a
+line of descent.
+
+If we survey the wealth of phenomena presented to us by secondary sexual
+characters, we can hardly fail to be convinced of the truth of the
+principle of sexual selection.  And certainly no one who has accepted
+natural selection should reject sexual selection, for, not only do the two
+processes rest upon the same basis, but they merge into one another, so
+that it is often impossible to say how much of a particular character
+depends on one and how much on the other form of selection.
+
+(b)  NATURAL SELECTION.
+
+An actual proof of the theory of sexual selection is out of the question,
+if only because we cannot tell when a variation attains to selection-value.
+It is certain that a delicate sense of smell is of value to the male moth
+in his search for the female, but whether the possession of one additional
+olfactory hair, or of ten, or of twenty additional hairs leads to the
+success of its possessor we are unable to tell.  And we are groping even
+more in the dark when we discuss the excitement caused in the female by
+agreeable perfumes, or by striking and beautiful colours.  That these do
+make an impression is beyond doubt; but we can only assume that slight
+intensifications of them give any advantage, and we MUST assume this SINCE
+OTHERWISE SECONDARY SEXUAL CHARACTERS REMAIN INEXPLICABLE.
+
+The same thing is true in regard to natural selection.  It is not possible
+to bring forward any actual proof of the selection-value of the initial
+stages, and the stages in the increase of variations, as has been already
+shown.  But the selection-value of a finished adaptation can in many cases
+be statistically determined.  Cesnola and Poulton have made valuable
+experiments in this direction.  The former attached forty-five individuals
+of the green, and sixty-five of the brown variety of the praying mantis
+(Mantis religiosa), by a silk thread to plants, and watched them for
+seventeen days.  The insects which were on a surface of a colour similar to
+their own remained uneaten, while twenty-five green insects on brown parts
+of plants had all disappeared in eleven days.
+
+The experiments of Poulton and Sanders ("Report of the British Association"
+(Bristol, 1898), London, 1899, pages 906-909.) were made with 600 pupae of
+Vanessa urticae, the "tortoise-shell butterfly."  The pupae were
+artificially attached to nettles, tree-trunks, fences, walls, and to the
+ground, some at Oxford, some at St Helens in the Isle of Wight.  In the
+course of a month 93 per cent of the pupae at Oxford were killed, chiefly
+by small birds, while at St Helens 68 per cent perished.  The experiments
+showed very clearly that the colour and character of the surface on which
+the pupa rests--and thus its own conspicuousness--are of the greatest
+importance.  At Oxford only the four pupae which were fastened to nettles
+emerged; all the rest--on bark, stones and the like--perished.  At St
+Helens the elimination was as follows:  on fences where the pupae were
+conspicuous, 92 per cent; on bark, 66 per cent; on walls, 54 per cent; and
+among nettles, 57 per cent.  These interesting experiments confirm our
+views as to protective coloration, and show further, THAT THE RATIO OF
+ELIMINATION IN THE SPECIES IS A VERY HIGH ONE, AND THAT THEREFORE SELECTION
+MUST BE VERY KEEN.
+
+We may say that the process of selection follows as a logical necessity
+from the fulfilment of the three preliminary postulates of the theory: 
+variability, heredity, and the struggle for existence, with its enormous
+ratio of elimination in all species.  To this we must add a fourth factor,
+the INTENSIFICATION of variations which Darwin established as a fact, and
+which we are now able to account for theoretically on the basis of germinal
+selection.  It may be objected that there is considerable uncertainty about
+this LOGICAL proof, because of our inability to demonstrate the selection-
+value of the initial stages and the individual stages of increase.  We have
+therefore to fall back on PRESUMPTIVE EVIDENCE.  This is to be found in THE
+INTERPRETATIVE VALUE OF THE THEORY.  Let us consider this point in greater
+detail.
+
+In the first place, it is necessary to emphasise what is often overlooked,
+namely, that the theory not only explains the TRANSFORMATIONS of species,
+it also explains THEIR REMAINING THE SAME; in addition to the principle of
+varying, it contains within itself that of PERSISTING.  It is part of the
+essence of selection, that it not only causes a part to VARY till it has
+reached its highest pitch of adaptation, but that it MAINTAINS IT AT THIS
+PITCH.  THIS CONSERVING INFLUENCE OF NATURAL SELECTION is of great
+importance, and was early recognised by Darwin; it follows naturally from
+the principle of the survival of the fittest.
+
+We understand from this how it is that a species which has become fully
+adapted to certain conditions of life ceases to vary, but remains
+"constant," as long as the conditions of life FOR IT remain unchanged,
+whether this be for thousands of years, or for whole geological epochs. 
+But the most convincing proof of the power of the principle of selection
+lies in the innumerable multitude of phenomena which cannot be explained in
+any other way.  To this category belong all structures which are only
+PASSIVELY of advantage to the organism, because none of these can have
+arisen by the alleged LAMARCKIAN PRINCIPLE.  These have been so often
+discussed that we need do no more than indicate them here.  Until quite
+recently the sympathetic coloration of animals--for instance, the whiteness
+of Arctic animals--was referred, at least in part, to the DIRECT influence
+of external factors, but the facts can best be explained by referring them
+to the processes of selection, for then it is unnecessary to make the
+gratuitous assumption that many species are sensitive to the stimulus of
+cold and that others are not.  The great majority of Arctic land-animals,
+mammals and birds, are white, and this proves that they were all able to
+present the variation which was most useful for them.  The sable is brown,
+but it lives in trees, where the brown colouring protects and conceals it
+more effectively.  The musk-sheep (Ovibos moschatus) is also brown, and
+contrasts sharply with the ice and snow, but it is protected from beasts of
+prey by its gregarious habit, and therefore it is of advantage to be
+visible from as great a distance as possible.  That so many species have
+been able to give rise to white varieties does not depend on a special
+sensitiveness of the skin to the influence of cold, but to the fact that
+Mammals and Birds have a general tendency to vary towards white.  Even with
+us, many birds--starlings, blackbirds, swallows, etc.--occasionally produce
+white individuals, but the white variety does not persist, because it
+readily falls a victim to the carnivores.  This is true of white fawns,
+foxes, deer, etc.  The whiteness, therefore, arises from internal causes,
+and only persists when it is useful.  A great many animals living in a
+GREEN ENVIRONMENT have become clothed in green, especially insects,
+caterpillars, and Mantidae, both persecuted and persecutors.
+
+That it is not the direct effect of the environment which calls forth the
+green colour is shown by the many kinds of caterpillar which rest on leaves
+and feed on them, but are nevertheless brown.  These feed by night and
+betake themselves through the day to the trunk of the tree, and hide in the
+furrows of the bark.  We cannot, however, conclude from this that they were
+UNABLE to vary towards green, for there are Arctic animals which are white
+only in winter and brown in summer (Alpine hare, and the ptarmigan of the
+Alps), and there are also green leaf-insects which remain green only while
+they are young and difficult to see on the leaf, but which become brown
+again in the last stage of larval life, when they have outgrown the leaf.
+They then conceal themselves by day, sometimes only among withered leaves
+on the ground, sometimes in the earth itself.  It is interesting that in
+one genus, Chaerocampa, one species is brown in the last stage of larval
+life, another becomes brown earlier, and in many species the last stage is
+not wholly brown, a part remaining green.  Whether this is a case of a
+double adaptation, or whether the green is being gradually crowded out by
+the brown, the fact remains that the same species, even the same
+individual, can exhibit both variations.  The case is the same with many of
+the leaf-like Orthoptera, as, for instance, the praying mantis (Mantis
+religiosa) which we have already mentioned.
+
+But the best proofs are furnished by those often-cited cases in which the
+insect bears a deceptive resemblance to another object.  We now know many
+such cases, such as the numerous imitations of green or withered leaves,
+which are brought about in the most diverse ways, sometimes by mere
+variations in the form of the insect and in its colour, sometimes by an
+elaborate marking, like that which occurs in the Indian leaf-butterflies,
+Kallima inachis.  In the single butterfly-genus Anaea, in the woods of
+South America, there are about a hundred species which are all gaily
+coloured on the upper surface, and on the reverse side exhibit the most
+delicate imitation of the colouring and pattern of a leaf, generally
+without any indication of the leaf-ribs, but extremely deceptive
+nevertheless.  Anyone who has seen only one such butterfly may doubt
+whether many of the insignificant details of the marking can really be of
+advantage to the insect.  Such details are for instance the apparent holes
+and splits in the apparently dry or half-rotten leaf, which are usually due
+to the fact that the scales are absent on a circular or oval patch so that
+the colourless wing-membrane lies bare, and one can look through the spot
+as through a window.  Whether the bird which is seeking or pursuing the
+butterflies takes these holes for dewdrops, or for the work of a devouring
+insect, does not affect the question; the mirror-like spot undoubtedly
+increases the general deceptiveness, for the same thing occurs in many
+leaf-butterflies, though not in all, and in some cases it is replaced in
+quite a peculiar manner.  In one species of Anaea (A. divina), the resting
+butterfly looks exactly like a leaf out of the outer edge of which a large
+semicircular piece has been eaten, possibly by a caterpillar; but if we
+look more closely it is obvious that there is no part of the wing absent,
+and that the semicircular piece is of a clear, pale yellow colour, while
+the rest of the wing is of a strongly contrasted dark brown.
+
+But the deceptive resemblance may be caused in quite a different manner.  I
+have often speculated as to what advantage the brilliant white C could give
+to the otherwise dusky-coloured "Comma butterfly" (Grapta C. album). 
+Poulton's recent observations ("Proc. Ent. Soc"., London, May 6, 1903.)
+have shown that this represents the imitation of a crack such as is often
+seen in dry leaves, and is very conspicuous because the light shines
+through it.
+
+The utility obviously lies in presenting to the bird the very familiar
+picture of a broken leaf with a clear shining slit, and we may conclude,
+from the imitation of such small details, that the birds are very sharp
+observers and that the smallest deviation from the usual arrests their
+attention and incites them to closer investigation.  It is obvious that
+such detailed--we might almost say such subtle--deceptive resemblances
+could only have come about in the course of long ages through the
+acquirement from time to time of something new which heightened the already
+existing resemblance.
+
+In face of facts like these there can be no question of chance, and no one
+has succeeded so far in finding any other explanation to replace that by
+selection.  For the rest, the apparent leaves are by no means perfect
+copies of a leaf; many of them only represent the torn or broken piece, or
+the half or two-thirds of a leaf, but then the leaves themselves frequently
+do not present themselves to the eye as a whole, but partially concealed
+among other leaves.  Even those butterflies which, like the species of
+Kallima and Anaea, represent the whole of a leaf with stalk, ribs, apex,
+and the whole breadth, are not actual copies which would satisfy a
+botanist; there is often much wanting.  In Kallima the lateral ribs of the
+leaf are never all included in the markings; there are only two or three on
+the left side and at most four or five on the right, and in many
+individuals these are rather obscure, while in others they are
+comparatively distinct.  This furnishes us with fresh evidence in favour of
+their origin through processes of selection, for a botanically perfect
+picture could not arise in this way; there could only be a fixing of such
+details as heightened the deceptive resemblance.
+
+Our postulate of origin through selection also enables us to understand why
+the leaf-imitation is on the lower surface of the wing in the diurnal
+Lepidoptera, and on the upper surface in the nocturnal forms, corresponding
+to the attitude of the wings in the resting position of the two groups.
+
+The strongest of all proofs of the theory, however, is afforded by cases of
+true "mimicry," those adaptations discovered by Bates in 1861, consisting
+in the imitation of one species by another, which becomes more and more
+like its model.  The model is always a species that enjoys some special
+protection from enemies, whether because it is unpleasant to taste, or
+because it is in some way dangerous.
+
+It is chiefly among insects and especially among butterflies that we find
+the greatest number of such cases.  Several of these have been minutely
+studied, and every detail has been investigated, so that it is difficult to
+understand how there can still be disbelief in regard to them.  If the many
+and exact observations which have been carefully collected and critically
+discussed, for instance by Poulton ("Essays on Evolution", 1889-1907,
+Oxford, 1908, passim, e.g. page 269.) were thoroughly studied, the
+arguments which are still frequently urged against mimicry would be found
+untenable; we can hardly hope to find more convincing proof of the
+actuality of the processes of selection than these cases put into our
+hands.  The preliminary postulates of the theory of mimicry have been
+disputed, for instance, that diurnal butterflies are persecuted and eaten
+by birds, but observations specially directed towards this point in India,
+Africa, America and Europe have placed it beyond all doubt.  If it were
+necessary I could myself furnish an account of my own observations on this
+point.
+
+In the same way it has been established by experiment and observation in
+the field that in all the great regions of distribution there are
+butterflies which are rejected by birds and lizards, their chief enemies,
+on account of their unpleasant smell or taste.  These butterflies are
+usually gaily and conspicuously coloured and thus--as Wallace first
+interpreted it--are furnished with an easily recognisable sign:  a sign of
+unpalatableness or WARNING COLOURS.  If they were not thus recognisable
+easily and from a distance, they would frequently be pecked at by birds,
+and then rejected because of their unpleasant taste; but as it is, the
+insect-eaters recognise them at once as unpalatable booty and ignore them.
+Such IMMUNE (The expression does not refer to all the enemies of this
+butterfly; against ichneumon-flies, for instance, their unpleasant smell
+usually gives no protection.) species, wherever they occur, are imitated by
+other palatable species, which thus acquire a certain degree of protection.
+
+It is true that this explanation of the bright, conspicuous colours is only
+a hypothesis, but its foundations,--unpalatableness, and the liability of
+other butterflies to be eaten,--are certain, and its consequences--the
+existence of mimetic palatable forms--confirm it in the most convincing
+manner.  Of the many cases now known I select one, which is especially
+remarkable, and which has been thoroughly investigated, Papilio dardanus
+(merope), a large, beautiful, diurnal butterfly which ranges from Abyssinia
+throughout the whole of Africa to the south coast of Cape Colony.
+
+The males of this form are everywhere ALMOST the same in colour and in form
+of wings, save for a few variations in the sparse black markings on the
+pale yellow ground.  But the females occur in several quite different forms
+and colourings, and one of these only, the Abyssinian form, is like the
+male, while the other three or four are MIMETIC, that is to say, they copy
+a butterfly of quite a different family the Danaids, which are among the
+IMMUNE forms.  In each region the females have thus copied two or three
+different immune species.  There is much that is interesting to be said in
+regard to these species, but it would be out of keeping with the general
+tenor of this paper to give details of this very complicated case of
+polymorphism in P. dardanus.  Anyone who is interested in the matter will
+find a full and exact statement of the case in as far as we know it, in
+Poulton's "Essays on Evolution" (pages 373-375). (Professor Poulton has
+corrected some wrong descriptions which I had unfortunately overlooked in
+the Plates of my book "Vortrage uber Descendenztheorie", and which refer to
+Papilio dardanus (merope).  These mistakes are of no importance as far as
+and understanding of the mimicry-theory is concerned, but I hope shortly to
+be able to correct them in a later edition.)  I need only add that three
+different mimetic female forms have been reared from the eggs of a single
+female in South Africa.  The resemblance of these forms to their immune
+models goes so far that even the details of the LOCAL forms of the models
+are copied by the mimetic species.
+
+It remains to be said that in Madagascar a butterfly, Papilio meriones,
+occurs, of which both sexes are very similar in form and markings to the
+non-mimetic male of P. dardanus, so that it probably represents the
+ancestor of this latter species.
+
+In face of such facts as these every attempt at another explanation must
+fail.  Similarly all the other details of the case fulfil the preliminary
+postulates of selection, and leave no room for any other interpretation. 
+That the males do not take on the protective colouring is easily explained,
+because they are in general more numerous, and the females are more
+important for the preservation of the species, and must also live longer in
+order to deposit their eggs.  We find the same state of things in many
+other species, and in one case (Elymnias undularis) in which the male is
+also mimetically coloured, it copies quite a differently coloured immune
+species from the model followed by the female.  This is quite intelligible
+when we consider that if there were TOO MANY false immune types, the birds
+would soon discover that there were palatable individuals among those with
+unpalatable warning colours.  Hence the imitation of different immune
+species by Papilio dardanus!
+
+I regret that lack of space prevents my bringing forward more examples of
+mimicry and discussing them fully.  But from the case of Papilio dardanus
+alone there is much to be learnt which is of the highest importance for our
+understanding of transformations.  It shows us chiefly what I once called,
+somewhat strongly perhaps, THE OMNIPOTENCE OF NATURAL SELECTION in answer
+to an opponent who had spoken of its "inadequacy."  We here see that one
+and the same species is capable of producing four or five different
+patterns of colouring and marking; thus the colouring and marking are not,
+as has often been supposed, a necessary outcome of the specific nature of
+the species, but a true adaptation, which cannot arise as a direct effect
+of climatic conditions, but solely through what I may call the sorting out
+of the variations produced by the species, according to their utility. 
+That caterpillars may be either green or brown is already something more
+than could have been expected according to the old conception of species,
+but that one and the same butterfly should be now pale yellow, with black;
+now red with black and pure white; now deep black with large, pure white
+spots; and again black with a large ochreous-yellow spot, and many small
+white and yellow spots; that in one sub-species it may be tailed like the
+ancestral form, and in another tailless like its Danaid model,--all this
+shows a far-reaching capacity for variation and adaptation that wide never
+have expected if we did not see the facts before us.  How it is possible
+that the primary colour-variations should thus be intensified and combined
+remains a puzzle even now; we are reminded of the modern three-colour
+printing,--perhaps similar combinations of the primary colours take place
+in this case; in any case the direction of these primary variations is
+determined by the artist whom we know as natural selection, for there is no
+other conceivable way in which the model could affect the butterfly that is
+becoming more and more like it.  The same climate surrounds all four forms
+of female; they are subject to the same conditions of nutrition.  Moreover,
+Papilio dardanus is by no means the only species of butterfly which
+exhibits different kinds of colour-pattern on its wings.  Many species of
+the Asiatic genus Elymnias have on the upper surface a very good imitation
+of an immune Euploeine (Danainae), often with a steel-blue ground-colour,
+while the under surface is well concealed when the butterfly is at rest,--
+thus there are two kinds of protective coloration each with a different
+meaning!  The same thing may be observed in many non-mimetic butterflies,
+for instance in all our species of Vanessa, in which the under side shows a
+grey-brown or brownish-black protective coloration, but we do not yet know
+with certainty what may be the biological significance of the gaily
+coloured upper surface.
+
+In general it may be said that mimetic butterflies are comparatively rare
+species, but there are exceptions, for instance Limenitis archippus in
+North America, of which the immune model (Danaida plexippus) also occurs in
+enormous numbers.
+
+In another mimicry-category the imitators are often more numerous than the
+models, namely in the case of the imitation of DANGEROUS INSECTS by
+harmless species.  Bees and wasps are dreaded for their sting, and they are
+copied by harmless flies of the genera Eristalis and Syrphus, and these
+mimics often occur in swarms about flowering plants without damage to
+themselves or to their models; they are feared and are therefore left
+unmolested.
+
+In regard also to the FAITHFULNESS OF THE COPY the facts are quite in
+harmony with the theory, according to which the resemblance must have
+arisen and increased BY DEGREES.  We can recognise this in many cases, for
+even now the mimetic species show very VARYING DEGREES OF RESEMBLANCE to
+their immune model.  If we compare, for instance, the many different
+imitators of Danaida chrysippus we find that, with their brownish-yellow
+ground-colour, and the position and size, and more or less sharp limitation
+of their clear marginal spots, they have reached very different degrees of
+nearness to their model.  Or compare the female of Elymnias undularis with
+its model Danaida genutia; there is a general resemblance, but the marking
+of the Danaida is very roughly imitated in Elymnias.
+
+Another fact that bears out the theory of mimicry is, that even when the
+resemblance in colour-pattern is very great, the WING-VENATION,  which is
+so constant, and so important in determining the systematic position of
+butterflies, is never affected by the variation.  The pursuers of the
+butterfly have no time to trouble about entomological intricacies.
+
+I must not pass over a discovery of Poulton's which is of great theoretical
+importance--that mimetic butterflies may reach the same effect by very
+different means.  ("Journ. Linn. Soc. London (Zool.)", Vol. XXVI. 1898,
+pages 598-602.)  Thus the glass-like transparency of the wing of a certain
+Ithomiine (Methona) and its Pierine mimic (Dismorphia orise) depends on a
+diminution in the size of the scales; in the Danaine genus Ituna it is due
+to the fewness of the scales, and in a third imitator, a moth (Castnia
+linus var. heliconoides) the glass-like appearance of the wing is due
+neither to diminution nor to absence of scales, but to their absolute
+colourlessness and transparency, and to the fact that they stand upright.
+In another moth mimic (Anthomyza) the arrangement of the transparent scales
+is normal.  Thus it is not some unknown external influence that has brought
+about the transparency of the wing in these five forms, as has sometimes
+been supposed.  Nor is it a hypothetical INTERNAL evolutionary tendency,
+for all three vary in a different manner.  The cause of this agreement can
+only lie in selection, which preserves and intensifies in each species the
+favourable variations that present themselves.  The great faithfulness of
+the copy is astonishing in these cases, for it is not THE WHOLE wing which
+is transparent; certain markings are black in colour, and these contrast
+sharply with the glass-like ground.  It is obvious that the pursuers of
+these butterflies must be very sharp-sighted, for otherwise the agreement
+between the species could never have been pushed so far.  The less the
+enemies see and observe, the more defective must the imitation be, and if
+they had been blind, no visible resemblance between the species which
+required protection could ever have arisen.
+
+A seemingly irreconcilable contradiction to the mimicry theory is presented
+in the following cases, which were known to Bates, who, however, never
+succeeded in bringing them into line with the principle of mimicry.
+
+In South America there are, as we have already said, many mimics of the
+immune Ithomiinae (or as Bates called them Heliconidae).  Among these there
+occur not merely species which are edible, and thus require the protection
+of a disguise, but others which are rejected on account of their
+unpalatableness.  How could the Ithomiine dress have developed in their
+case, and of what use is it, since the species would in any case be immune?
+In Eastern Brazil, for instance, there are four butterflies, which bear a
+most confusing resemblance to one another in colour, marking, and form of
+wing, and all four are unpalatable to birds.  They belong to four different
+genera and three sub-families, and we have to inquire:  Whence came this
+resemblance and what end does it serve?  For a long time no satisfactory
+answer could be found, but Fritz Muller (In "Kosmos", 1879, page 100.), 
+seventeen years after Bates, offered a solution to the riddle, when he
+pointed out that young birds could not have an instinctive knowledge of the
+unpalatableness of the Ithomiines, but must learn by experience which
+species were edible and which inedible.  Thus each young bird must have
+tasted at least one individual of each inedible species and discovered its
+unpalatability, before it learnt to avoid, and thus to spare the species. 
+But if the four species resemble each other very closely the bird will
+regard them all as of the same kind, and avoid them all.  Thus there
+developed a process of selection which resulted in the survival of the
+Ithomiine-like individuals, and in so great an increase of resemblance
+between the four species, that they are difficult to distinguish one from
+another even in a collection.  The advantage for the four species, living
+side by side as they do e.g. in Bahia, lies in the fact that only one
+individual from the MIMICRY-RING ("inedible association") need be tasted by
+a young bird, instead of at least four individuals, as would otherwise be
+the case.  As the number of young birds is great, this makes a considerable
+difference in the ratio of elimination.
+
+These interesting mimicry-rings (trusts), which have much significance for
+the theory, have been the subject of numerous and careful investigations,
+and at least their essential features are now fully established.  Muller
+took for granted, without making any investigations, that young birds only
+learn by experience to distinguish between different kinds of victims.  But
+Lloyd Morgan's ("Habit and Instinct", London, 1896.) experiments with young
+birds proved that this is really the case, and at the same time furnished
+an additional argument against the LAMARCKIAN PRINCIPLE.
+
+In addition to the mimicry-rings first observed in South America, others
+have been described from Tropical India by Moore, and by Poulton and Dixey
+from Africa, and we may expect to learn many more interesting facts in this
+connection.  Here again the preliminary postulates of the theory are
+satisfied.  And how much more that would lead to the same conclusion might
+be added!
+
+As in the case of mimicry many species have come to resemble one another
+through processes of selection, so we know whole classes of phenomena in
+which plants and animals have become adapted to one another, and have thus
+been modified to a considerable degree.  I refer particularly to the
+relation between flowers and insects; but as there is an article on "The
+Biology of Flowers" in this volume, I need not discuss the subject, but
+will confine myself to pointing out the significance of these remarkable
+cases for the theory of selection.  Darwin has shown that the originally
+inconspicuous blossoms of the phanerogams were transformed into flowers
+through the visits of insects, and that, conversely, several large orders
+of insects have been gradually modified by their association with flowers,
+especially as regards the parts of their body actively concerned.  Bees and
+butterflies in particular have become what they are through their relation
+to flowers.  In this case again all that is apparently contradictory to the
+theory can, on closer investigation, be beautifully interpreted in
+corroboration of it.  Selection can give rise only to what is of use to the
+organism actually concerned, never to what is of use to some other
+organism, and we must therefore expect to find that in flowers only
+characters of use to THEMSELVES have arisen, never characters which are of
+use to insects only, and conversely that in the insects characters useful
+to them and not merely to the plants would have originated.  For a long
+time it seemed as if an exception to this rule existed in the case of the
+fertilisation of the yucca blossoms by a little moth, Pronuba yuccasella. 
+This little moth has a sickle-shaped appendage to its mouth-parts which
+occurs in no other Lepidopteron, and which is used for pushing the yellow
+pollen into the opening of the pistil, thus fertilising the flower.  Thus
+it appears as if a new structure, which is useful only to the plant, has
+arisen in the insect.  But the difficulty is solved as soon as we learn
+that the moth lays its eggs in the fruit-buds of the Yucca, and that the
+larvae, when they emerge, feed on the developing seeds.  In effecting the
+fertilisation of the flower the moth is at the same time making provision
+for its own offspring, since it is only after fertilisation that the seeds
+begin to develop.  There is thus nothing to prevent our referring this
+structural adaptation in Pronuba yuccasella to processes of selection,
+which have gradually transformed the maxillary palps of the female into the
+sickle-shaped instrument for collecting the pollen, and which have at the
+same time developed in the insect the instinct to press the pollen into the
+pistil.
+
+In this domain, then, the theory of selection finds nothing but
+corroboration, and it would be impossible to substitute for it any other
+explanation, which, now that the facts are so well known, could be regarded
+as a serious rival to it.  That selection is a factor, and a very powerful
+factor in the evolution of organisms, can no longer be doubted.  Even
+although we cannot bring forward formal proofs of it IN DETAIL, cannot
+calculate definitely the size of the variations which present themselves,
+and their selection-value, cannot, in short, reduce the whole process to a
+mathematical formula, yet we must assume selection, because it is the only
+possible explanation applicable to whole classes of phenomena, and because,
+on the other hand, it is made up of factors which we know can be proved
+actually to exist, and which, IF they exist, must of logical necessity
+cooperate in the manner required by the theory.  WE MUST ACCEPT IT BECAUSE
+THE PHENOMENA OF EVOLUTION AND ADAPTATION MUST HAVE A NATURAL BASIS, AND
+BECAUSE IT IS THE ONLY POSSIBLE EXPLANATION OF THEM.  (This has been
+discussed in many of my earlier works.  See for instance "The All-
+Sufficiency of Natural Selection, a reply to Herbert Spencer", London,
+1893.)
+
+Many people are willing to admit that selection explains adaptations, but
+they maintain that only a part of the phenomena are thus explained, because
+everything does not depend upon adaptation.  They regard adaptation as, so
+to speak, a special effort on the part of Nature, which she keeps in
+readiness to meet particularly difficult claims of the external world on
+organisms.  But if we look at the matter more carefully we shall find that
+adaptations are by no means exceptional, but that they are present
+everywhere in such enormous numbers, that it would be difficult in regard
+to any structure whatever, to prove that adaptation had NOT played a part
+in its evolution.
+
+How often has the senseless objection been urged against selection that it
+can create nothing, it can only reject.  It is true that it cannot create
+either the living substance or the variations of it; both must be given. 
+But in rejecting one thing it preserves another, intensifies it, combines
+it, and in this way CREATES what is new.  EVERYTHING in organisms depends
+on adaptation; that is to say, everything must be admitted through the
+narrow door of selection, otherwise it can take no part in the building up
+of the whole.  But, it is asked, what of the direct effect of external
+conditions, temperature, nutrition, climate and the like?  Undoubtedly
+these can give rise to variations, but they too must pass through the door
+of selection, and if they cannot do this they are rejected, eliminated from
+the constitution of the species.
+
+It may, perhaps, be objected that such external influences are often of a
+compelling power, and that every animal MUST submit to them, and that thus
+selection has no choice and can neither select nor reject.  There may be
+such cases; let us assume for instance that the effect of the cold of the
+Arctic regions was to make all the mammals become black; the result would
+be that they would all be eliminated by selection, and that no mammals
+would be able to live there at all.  But in most cases a certain percentage
+of animals resists these strong influences, and thus selection secures a
+foothold on which to work, eliminating the unfavourable variation, and
+establishing a useful colouring, consistent with what is required for the
+maintenance of the species.
+
+Everything depends upon adaptation!  We have spoken much of adaptation in
+colouring, in connection with the examples brought into prominence by
+Darwin, because these are conspicuous, easily verified, and at the same
+time convincing for the theory of selection.  But is it only desert and
+polar animals whose colouring is determined through adaptation?  Or the
+leaf-butterflies, and the mimetic species, or the terrifying markings, and
+"warning-colours" and a thousand other kinds of sympathetic colouring?  It
+is, indeed, never the colouring alone which makes up the adaptation; the
+structure of the animal plays a part, often a very essential part, in the
+protective disguise, and thus MANY variations may cooperate towards ONE
+common end.  And it is to be noted that it is by no means only external
+parts that are changed; internal parts are ALWAYS modified at the same
+time--for instance, the delicate elements of the nervous system on which
+depend the INSTINCT of the insect to hold its wings, when at rest, in a
+perfectly definite position, which, in the leaf-butterfly, has the effect
+of bringing the two pieces on which the marking occurs on the anterior and
+posterior wing into the same direction, and thus displaying as a whole the
+fine curve of the midrib on the seeming leaf. But the wing-holding instinct
+is not regulated in the same way in all leaf-butterflies; even our
+indigenous species of Vanessa, with their protective ground-colouring, have
+quite a distinctive way of holding their wings so that the greater part of
+the anterior wing is covered by the posterior when the butterfly is at
+rest.  But the protective colouring appears on the posterior wing and on
+the tip of the anterior, TO PRECISELY THE DISTANCE TO WHICH IT IS LEFT
+UNCOVERED.  This occurs, as Standfuss has shown, in different degree in our
+two most nearly allied species, the uncovered portion being smaller in V.
+urticae than in V. polychloros.  In this case, as in most leaf-butterflies,
+the holding of the wing was probably the primary character; only after that
+was thoroughly established did the protective marking develop.  In any
+case, the instinctive manner of holding the wings is associated with the
+protective colouring, and must remain as it is if the latter is to be
+effective.  How greatly instincts may change, that is to say, may be
+adapted, is shown by the case of the Noctuid "shark" moth, Xylina vetusta. 
+This form bears a most deceptive resemblance to a piece of rotten wood, and
+the appearance is greatly increased by the modification of the innate
+impulse to flight common to so many animals, which has here been
+transformed into an almost contrary instinct.  This moth does not fly away
+from danger, but "feigns death," that is, it draws antennae, legs and wings
+close to the body, and remains perfectly motionless.  It may be touched,
+picked up, and thrown down again, and still it does not move.  This
+remarkable instinct must surely have developed simultaneously with the
+wood-colouring; at all events, both cooperating variations are now present,
+and prove that both the external and the most minute internal structure
+have undergone a process of adaptation.
+
+The case is the same with all structural variations of animal parts, which
+are not absolutely insignificant.  When the insects acquired wings they
+must also have acquired the mechanism with which to move them--the
+musculature, and the nervous apparatus necessary for its automatic
+regulation.  All instincts depend upon compound reflex mechanisms and are
+just as indispensable as the parts they have to set in motion, and all may
+have arisen through processes of selection if the reasons which I have
+elsewhere given for this view are correct.  ("The Evolution Theory",
+London, 1904, page 144.)
+
+Thus there is no lack of adaptations within the organism, and particularly
+in its most important and complicated parts, so that we may say that there
+is no actively functional organ that has not undergone a process of
+adaptation relative to its function and the requirements of the organism. 
+Not only is every gland structurally adapted, down to the very minutest
+histological details, to its function, but the function is equally minutely
+adapted to the needs of the body.  Every cell in the mucous lining of the
+intestine is exactly regulated in its relation to the different nutritive
+substances, and behaves in quite a different way towards the fats, and
+towards nitrogenous substances, or peptones.
+
+I have elsewhere called attention to the many adaptations of the whale to
+the surrounding medium, and have pointed out--what has long been known, but
+is not universally admitted, even now--that in it a great number of
+important organs have been transformed in adaptation to the peculiar
+conditions of aquatic life, although the ancestors of the whale must have
+lived, like other hair-covered mammals, on land.  I cited a number of these
+transformations--the fish-like form of the body, the hairlessness of the
+skin, the transformation of the fore-limbs to fins, the disappearance of
+the hind-limbs and the development of a tail fin, the layer of blubber
+under the skin, which affords the protection from cold necessary to a warm-
+blooded animal, the disappearance of the ear-muscles and the auditory
+passages, the displacement of the external nares to the forehead for the
+greater security of the breathing-hole during the brief appearance at the
+surface, and certain remarkable changes in the respiratory and circulatory
+organs which enable the animal to remain for a long time under water.  I
+might have added many more, for the list of adaptations in the whale to
+aquatic life is by no means exhausted; they are found in the histological
+structure and in the minutest combinations in the nervous system.  For it
+is obvious that a tail-fin must be used in quite a different way from a
+tail, which serves as a fly-brush in hoofed animals, or as an aid to
+springing in the kangaroo or as a climbing organ; it will require quite
+different reflex-mechanisms and nerve-combinations in the motor centres.
+
+I used this example in order to show how unnecessary it is to assume a
+special internal evolutionary power for the phylogenesis of species, for
+this whole order of whales is, so to speak, MADE UP OF ADAPTATIONS; it
+deviates in many essential respects from the usual mammalian type, and all
+the deviations are adaptations to aquatic life.  But if precisely the most
+essential features of the organisation thus depend upon adaptation, what is
+left for a phyletic force to do, since it is these essential features of
+the structure it would have to determine?  There are few people now who
+believe in a phyletic evolutionary power, which is not made up of the
+forces known to us--adaptation and heredity--but the conviction that EVERY
+part of an organism depends upon adaptation has not yet gained a firm
+footing.  Nevertheless, I must continue to regard this conception as the
+correct one, as I have long done.
+
+I may be permitted one more example.  The feather of a bird is a marvellous
+structure, and no one will deny that as a whole it depends upon adaptation.
+But what part of it DOES NOT depend upon adaptation?  The hollow quill, the
+shaft with its hard, thin, light cortex, and the spongy substance within
+it, its square section compared with the round section of the quill, the
+flat barbs, their short, hooked barbules which, in the flight-feathers,
+hook into one another with just sufficient firmness to resist the pressure
+of the air at each wing-beat, the lightness and firmness of the whole
+apparatus, the elasticity of the vane, and so on.  And yet all this belongs
+to an organ which is only passively functional, and therefore can have
+nothing to do with the LAMARCKIAN PRINCIPLE.  Nor can the feather have
+arisen through some magical effect of temperature, moisture, electricity,
+or specific nutrition, and thus selection is again our only anchor of
+safety.
+
+But--it will be objected--the substance of which the feather consists, this
+peculiar kind of horny substance, did not first arise through selection in
+the course of the evolution of the birds, for it formed the covering of the
+scales of their reptilian ancestors.  It is quite true that a similar
+substance covered the scales of the Reptiles, but why should it not have
+arisen among them through selection?  Or in what other way could it have
+arisen, since scales are also passively useful parts?  It is true that if
+we are only to call adaptation what has been acquired by the species we
+happen to be considering, there would remain a great deal that could not be
+referred to selection; but we are postulating an evolution which has
+stretched back through aeons, and in the course of which innumerable
+adaptations took place, which had not merely ephemeral persistence in a
+genus, a family or a class, but which was continued into whole Phyla of
+animals, with continual fresh adaptations to the special conditions of each
+species, family, or class, yet with persistence of the fundamental
+elements.  Thus the feather, once acquired, persisted in all birds, and the
+vertebral column, once gained by adaptation in the lowest forms, has
+persisted in all the Vertebrates, from Amphioxus upwards, although with
+constant readaptation to the conditions of each particular group.  Thus
+everything we can see in animals is adaptation, whether of to-day, or of
+yesterday, or of ages long gone by; every kind of cell, whether glandular,
+muscular, nervous, epidermic, or skeletal, is adapted to absolutely
+definite and specific functions, and every organ which is composed of these
+different kinds of cells contains them in the proper proportions, and in
+the particular arrangement which best serves the function of the organ; it
+is thus adapted to its function.
+
+All parts of the organism are tuned to one another, that is, THEY ARE
+ADAPTED TO ONE ANOTHER, and in the same way THE ORGANISM AS A WHOLE IS
+ADAPTED TO THE CONDITIONS OF ITS LIFE, AND IT IS SO AT EVERY STAGE OF ITS
+EVOLUTION.
+
+But all adaptations CAN be referred to selection; the only point that
+remains doubtful is whether they all MUST be referred to it.
+
+However that may be, whether the LAMARCKIAN PRINCIPLE is a factor that has
+cooperated with selection in evolution, or whether it is altogether
+fallacious, the fact remains, that selection is the cause of a great part
+of the phyletic evolution of organisms on our earth.  Those who agree with
+me in rejecting the LAMARCKIAN PRINCIPLE will regard selection as the only
+GUIDING factor in evolution, which creates what is new out of the
+transmissible variations, by ordering and arranging these, selecting them
+in relation to their number and size, as the architect does his building-
+stones so that a particular style must result.  ("Variation under
+Domestication", 1875 II. pages 426, 427.)  But the building-stones
+themselves, the variations, have their basis in the influences which cause
+variation in those vital units which are handed on from one generation to
+another, whether, taken together they form the WHOLE organism, as in
+Bacteria and other low forms of life, or only a germ-substance, as in
+unicellular and multicellular organisms.  (The Author and Editor are
+indebted to Professor Poulton for kindly assisting in the revision of the
+proof of this Essay.)
+
+
+IV.  VARIATION. 
+
+By HUGO DE VRIES,
+Professor of Botany in the University of Amsterdam.
+
+I.  DIFFERENT KINDS OF VARIABILITY.
+
+Before Darwin, little was known concerning the phenomena of variability. 
+The fact, that hardly two leaves on a tree were exactly the same, could not
+escape observation:  small deviations of the same kind were met with
+everywhere, among individuals as well as among the organs of the same
+plant.  Larger aberrations, spoken of as monstrosities, were for a long
+time regarded as lying outside the range of ordinary phenomena.  A special
+branch of inquiry, that of Teratology, was devoted to them, but it
+constituted a science by itself, sometimes connected with morphology, but
+having scarcely any bearing on the processes of evolution and heredity.
+
+Darwin was the first to take a broad survey of the whole range of
+variations in the animal and vegetable kingdoms.  His theory of Natural
+Selection is based on the fact of variability.  In order that this
+foundation should be as strong as possible he collected all the facts,
+scattered in the literature of his time, and tried to arrange them in a
+scientific way.  He succeeded in showing that variations may be grouped
+along a line of almost continuous gradations, beginning with simple
+differences in size and ending with monstrosities.  He was struck by the
+fact that, as a rule, the smaller the deviations, the more frequently they
+appear, very abrupt breaks in characters being of rare occurrence.
+
+Among these numerous degrees of variability Darwin was always on the look
+out for those which might, with the greatest probability, be considered as
+affording material for natural selection to act upon in the development of
+new species.  Neither of the extremes complied with his conceptions.  He
+often pointed out, that there are a good many small fluctuations, which in
+this respect must be absolutely useless.  On the other hand, he strongly
+combated the belief, that great changes would be necessary to explain the
+origin of species.  Some authors had propounded the idea that highly
+adapted organs, e.g. the wings of a bird, could not have been developed in
+any other way than by a comparatively sudden modification of a well defined
+and important kind.  Such a conception would allow of great breaks or
+discontinuity in the evolution of highly differentiated animals and plants,
+shortening the time for the evolution of the whole organic kingdom and
+getting over numerous difficulties inherent in the theory of slow and
+gradual progress.  It would, moreover, account for the genetic relation of
+the larger groups of both animals and plants.  It would, in a word,
+undoubtedly afford an easy means of simplifying the problem of descent with
+modification.
+
+Darwin, however, considered such hypotheses as hardly belonging to the
+domain of science; they belong, he said, to the realm of miracles.  That
+species have a capacity for change is admitted by all evolutionists; but
+there is no need to invoke modifications other than those represented by
+ordinary variability.  It is well known that in artificial selection this
+tendency to vary has given rise to numerous distinct races, and there is no
+reason for denying that it can do the same in nature, by the aid of natural
+selection.  On both lines an advance may be expected with equal
+probability.
+
+His main argument, however, is that the most striking and most highly
+adapted modifications may be acquired by successive variations.  Each of
+these may be slight, and they may affect different organs, gradually
+adapting them to the same purpose.  The direction of the adaptations will
+be determined by the needs in the struggle for life, and natural selection
+will simply exclude all such changes as occur on opposite or deviating
+lines.  In this way, it is not variability itself which is called upon to
+explain beautiful adaptations, but it is quite sufficient to suppose that
+natural selection has operated during long periods in the same way. 
+Eventually, all the acquired characters, being transmitted together, would
+appear to us, as if they had all been simultaneously developed.
+
+Correlations must play a large part in such special evolutions:  when one
+part is modified, so will be other parts.  The distribution of nourishment
+will come in as one of the causes, the reactions of different organs to the
+same external influences as another.  But no doubt the more effective cause
+is that of the internal correlations, which, however, are still but dimly
+understood.  Darwin repeatedly laid great stress on this view, although a
+definite proof of its correctness could not be given in his time.  Such
+proof requires the direct observation of a mutation, and it should be
+stated here that even the first observations made in this direction have
+clearly confirmed Darwin's ideas.  The new evening primroses which have
+sprung in my garden from the old form of Oenothera Lamarckiana, and which
+have evidently been derived from it, in each case, by a single mutation, do
+not differ from their parent species in one character only, but in almost
+all their organs and qualities.  Oenothera gigas, for example, has stouter
+stems and denser foliage; the leaves are larger and broader; its thick
+flower-buds produce gigantic flowers, but only small fruits with large
+seeds.  Correlative changes of this kind are seen in all my new forms, and
+they lend support to the view that in the gradual development of highly
+adapted structures, analogous correlations may have played a large part. 
+They easily explain large deviations from an original type, without
+requiring the assumption of too many steps.
+
+Monstrosities, as their name implies, are widely different in character
+from natural species; they cannot, therefore, be adduced as evidence in the
+investigation of the origin of species.  There is no doubt that they may
+have much in common as regards their manner of origin, and that the origin
+of species, once understood, may lead to a better understanding of the
+monstrosities.  But the reverse is not true, at least not as regards the
+main lines of development.  Here, it is clear, monstrosities cannot have
+played a part of any significance.
+
+Reversions, or atavistic changes, would seem to give a better support to
+the theory of descent through modifications.  These have been of paramount
+importance on many lines of evolution of the animal as well as of the
+vegetable kingdom.  It is often assumed that monocotyledons are descended
+from some lower group of dicotyledons, probably allied to that which
+includes the buttercup family.  On this view the monocotyledons must be
+assumed to have lost the cambium and all its influence on secondary growth,
+the differentiation of the flower into calyx and corolla, the second
+cotyledon or seed-leaf and several other characters.  Losses of characters
+such as these may have been the result of abrupt changes, but this does not
+prove that the characters themselves have been produced with equal
+suddenness.  On the contrary, Darwin shows very convincingly that a
+modification may well be developed by a series of steps, and afterwards
+suddenly disappear.  Many monstrosities, such as those represented by
+twisted stems, furnish direct proofs in support of this view, since they
+are produced by the loss of one character and this loss implies secondary
+changes in a large number of other organs and qualities.
+
+Darwin criticises in detail the hypothesis of great and abrupt changes and
+comes to the conclusion that it does not give even a shadow of an
+explanation of the origin of species.  It is as improbable as it is
+unnecessary.
+
+Sports and spontaneous variations must now be considered.  It is well known
+that they have produced a large number of fine horticultural varieties. 
+The cut-leaved maple and many other trees and shrubs with split leaves are
+known to have been produced at a single step; this is true in the case of
+the single-leaf strawberry plant and of the laciniate variety of the
+greater celandine:  many white flowers, white or yellow berries and
+numerous other forms had a similar origin.  But changes such as these do
+not come under the head of adaptations, as they consist for the most part
+in the loss of some quality or organ belonging to the species from which
+they were derived.  Darwin thinks it impossible to attribute to this cause
+the innumerable structures, which are so well adapted to the habits of life
+of each species.  At the present time we should say that such adaptations
+require progressive modifications, which are additions to the stock of
+qualities already possessed by the ancestors, and cannot, therefore, be
+explained on the ground of a supposed analogy with sports, which are for
+the most part of a retrogressive nature.
+
+Excluding all these more or less sudden changes, there remains a long
+series of gradations of variability, but all of these are not assumed by
+Darwin to be equally fit for the production of new species.  In the first
+place, he disregards all mere temporary variations, such as size, albinism,
+etc.; further, he points out that very many species have almost certainly
+been produced by steps, not greater, and probably not very much smaller,
+than those separating closely related varieties.  For varieties are only
+small species.  Next comes the question of polymorphic species:  their
+occurrence seems to have been a source of much doubt and difficulty in
+Darwin's mind, although at present it forms one of the main supports of the
+prevailing explanation of the origin of new species.  Darwin simply states
+that this kind of variability seems to be of a peculiar nature; since
+polymorphic species are now in a stable condition their occurrence gives no
+clue as to the mode of origin of new species.  Polymorphic species are the
+expression of the result of previous variability acting on a large scale;
+but they now simply consist of more or less numerous elementary species,
+which, as far as we know, do not at present exhibit a larger degree of
+variability than any other more uniform species.  The vernal whitlow-grass
+(Draba verna) and the wild pansy are the best known examples; both have
+spread over almost the whole of Europe and are split up into hundreds of
+elementary forms.  These sub-species show no signs of any extraordinary
+degree of variability, when cultivated under conditions necessary for the
+exclusion of inter-crossing.  Hooker has shown, in the case of some ferns
+distributed over still wider areas, that the extinction of some of the
+intermediate forms in such groups would suffice to justify the elevation of
+the remaining types to the rank of distinct species.  Polymorphic species
+may now be regarded as the link which unites ordinary variability with the
+historical production of species.  But it does not appear that they had
+this significance for Darwin; and, in fact, they exhibit no phenomena which
+could explain the processes by which one species has been derived from
+another.  By thus narrowing the limits of the species-producing variability
+Darwin was led to regard small deviations as the source from which natural
+selection derives material upon which to act.  But even these are not all
+of the same type, and Darwin was well aware of the fact.
+
+It should here be pointed out that in order to be selected, a change must
+first have been produced.  This proposition, which now seems self-evident,
+has, however, been a source of much difference of opinion among Darwin's
+followers.  The opinion that natural selection produces changes in useful
+directions has prevailed for a long time.  In other words, it was assumed
+that natural selection, by the simple means of singling out, could induce
+small and useful changes to increase and to reach any desired degree of
+deviation from the original type.  In my opinion this view was never
+actually held by Darwin.  It is in contradiction with the acknowledged aim
+of all his work,--the explanation of the origin of species by means of
+natural forces and phenomena only.  Natural selection acts as a sieve; it
+does not single out the best variations, but it simply destroys the larger
+number of those which are, from some cause or another, unfit for their
+present environment.  In this way it keeps the strains up to the required
+standard, and, in special circumstances, may even improve them.
+
+Returning to the variations which afford the material for the sieving-
+action of natural selection, we may distinguish two main kinds.  It is true
+that the distinction between these was not clear at the time of Darwin, and
+that he was unable to draw a sharp line between them.  Nevertheless, in
+many cases, he was able to separate them, and he often discussed the
+question which of the two would be the real source of the differentiation
+of species.  Certain variations constantly occur, especially such as are
+connected with size, weight, colour, etc.  They are usually too small for
+natural selection to act upon, having hardly any influence in the struggle
+for life:  others are more rare, occurring only from time to time, perhaps
+once or twice in a century, perhaps even only once in a thousand years. 
+Moreover, these are of another type, not simply affecting size, number or
+weight, but bringing about something new, which may be useful or not. 
+Whenever the variation is useful natural selection will take hold of it and
+preserve it; in other cases the variation may either persist or disappear.
+
+In his criticism of miscellaneous objections brought forward against the
+theory of natural selection after the publication of the first edition of
+"The Origin of Species", Darwin stated his view on this point very
+clearly:--"The doctrine of natural selection or the survival of the
+fittest, which implies that when variations or individual differences of a
+beneficial nature happen to arise, these will be preserved."  ("Origin of
+Species" (6th edition), page 169, 1882.)  In this sentence the words
+"HAPPEN TO ARISE" appear to me of prominent significance.  They are
+evidently due to the same general conception which prevailed in Darwin's
+Pangenesis hypothesis.  (Cf. de Vries, "Intracellulare Pangenesis", page
+73, Jena, 1889, and "Die Mutationstheorie", I. page 63.  Leipzig, 1901.)
+
+A distinction is indicated between ordinary fluctuations which are always
+present, and such variations as "happen to arise" from time to time.  ((I
+think it right to point out that the interpretation of this passage from
+the "Origin" by Professor de Vries is not accepted as correct either by Mr
+Francis Darwin or by myself.  We do not believe that Darwin intended to
+draw any distinction between TWO TYPES of variation; the words "when
+variations or individual differences of a beneficial nature happen to
+arise" are not in our opinion meant to imply a distinction between ordinary
+fluctuations and variations which "happen to arise," but we believe that
+"or" is here used in the sense of ALIAS.  With the permission of Professor
+de Vries, the following extract is quoted from a letter in which he replied
+to the objection raised to his reading of the passage in question:
+
+"As to your remarks on the passage on page 6, I agree that it is now
+impossible to see clearly how far Darwin went in his distinction of the
+different kinds of variability.  Distinctions were only dimly guessed at by
+him.  But in our endeavour to arrive at a true conception of his view I
+think that the chapter on Pangenesis should be our leading guide, and that
+we should try to interpret the more difficult passages by that chapter.  A
+careful and often repeated study of the Pangenesis hypothesis has convinced
+me that Darwin, when he wrote that chapter, was well aware that ordinary
+variability has nothing to do with evolution, but that other kinds of
+variation were necessary.  In some chapters he comes nearer to a clear
+distinction than in others.  To my mind the expression 'happen to arise' is
+the sharpest indication of his inclining in this direction.  I am quite
+convinced that numerous expressions in his book become much clearer when
+looked at in this way."
+
+The statement in this passage that "Darwin was well aware that ordinary
+variability has nothing to do with evolution, but that other kinds of
+variation were necessary" is contradicted by many passages in the "Origin".
+A.C.S.))  The latter afford the material for natural selection to act upon
+on the broad lines of organic development, but the first do not. 
+Fortuitous variations are the species-producing kind, which the theory
+requires; continuous fluctuations constitute, in this respect, a useless
+type.
+
+Of late, the study of variability has returned to the recognition of this
+distinction.  Darwin's variations, which from time to time happen to arise,
+are MUTATIONS, the opposite type being commonly designed fluctuations.  A
+large mass of facts, collected during the last few decades, has confirmed
+this view, which in Darwin's time could only be expressed with much
+reserve, and everyone knows that Darwin was always very careful in
+statements of this kind.
+
+From the same chapter I may here cite the following paragraph:  "Thus as I
+am inclined to believe, morphological differences,...such as the
+arrangement of the leaves, the divisions of the flower or of the ovarium,
+the position of the ovules, etc.--first appeared in many cases as
+fluctuating variations, which sooner or later became constant through the
+nature of the organism and of the surrounding conditions...but NOT THROUGH
+NATURAL SELECTION (The italics are mine (H. de V.).); for as these
+morphological characters do not affect the welfare of the species, any
+slight deviation in them could not have been governed or accumulated
+through this latter agency."  ("Origin of Species" (6th edition), page
+176.)  We thus see that in Darwin's opinion, all small variations had not
+the same importance.  In favourable circumstances some could become
+constant, but others could not.
+
+Since the appearance of the first edition of "The Origin of Species"
+fluctuating variability has been thoroughly studied by Quetelet.  He
+discovered the law, which governs all phenomena of organic life falling
+under this head.  It is a very simple law, and states that individual
+variations follow the laws of probability.  He proved it, in the first
+place, for the size of the human body, using the measurements published for
+Belgian recruits; he then extended it to various other measurements of
+parts of the body, and finally concluded that it must be of universal
+validity for all organic beings.  It must hold true for all characters in
+man, physical as well as intellectual and moral qualities; it must hold
+true for the plant kingdom as well as for the animal kingdom; in short, it
+must include the whole living world.
+
+Quetelet's law may be most easily studied in those cases where the
+variability relates to measure, number and weight, and a vast number of
+facts have since confirmed its exactness and its validity for all kinds of
+organisms, organs and qualities.  But if we examine it more closely, we
+find that it includes just those minute variations, which, as Darwin
+repeatedly pointed out, have often no significance for the origin of
+species.  In the phenomena, described by Quetelet's law nothing "happens to
+arise"; all is governed by the common law, which states that small
+deviations from the mean type are frequent, but that larger aberrations are
+rare, the rarer as they are larger.  Any degree of variation will be found
+to occur, if only the number of individuals studied is large enough:  it is
+even possible to calculate before hand, how many specimens must be compared
+in order to find a previously fixed degree of deviation.
+
+The variations, which from time to time happen to appear, are evidently not
+governed by this law.  They cannot, as yet, be produced at will:  no
+sowings of thousands or even of millions of plants will induce them,
+although by such means the chance of their occurring will obviously be
+increased.  But they are known to occur, and to occur suddenly and
+abruptly.  They have been observed especially in horticulture, where they
+are ranged in the large and ill-defined group called sports.  Korschinsky
+has collected all the evidence which horticultural literature affords on
+this point.  (S. Korschinsky, "Heterogenesis und Evolution", "Flora", Vol.
+LXXXIX. pages 240-363, 1901.)  Several cases of the first appearance of a
+horticultural novelty have been recorded:  this has always happened in the
+same way; it appeared suddenly and unexpectedly without any definite
+relation to previously existing variability.  Dwarf types are one of the
+commonest and most favourite varieties of flowering plants; they are not
+originated by a repeated selection of the smallest specimens, but appear at
+once, without intermediates and without any previous indication.  In many
+instances they are only about half the height of the original type, thus
+constituting obvious novelties.  So it is in other cases described by
+Korschinsky:  these sports or mutations are now recognised to be the main
+source of varieties of horticultural plants.
+
+As already stated, I do not pretend that the production of horticultural
+novelties is the prototype of the origin of new species in nature.  I
+assume that they are, as a rule, derived from the parent species by the
+loss of some organ or quality, whereas the main lines of the evolution of
+the animal and vegetable kingdom are of course determined by progressive
+changes.  Darwin himself has often pointed out this difference.  But the
+saltatory origin of horticultural novelties is as yet the simplest parallel
+for natural mutations, since it relates to forms and phenomena, best known
+to the general student of evolution.
+
+The point which I wish to insist upon is this.  The difference between
+small and ever present fluctuations and rare and more sudden variations was
+clear to Darwin, although the facts known at his time were too meagre to
+enable a sharp line to be drawn between these two great classes of
+variability.  Since Darwin's time evidence, which proves the correctness of
+his view, has accumulated with increasing rapidity.  Fluctuations
+constitute one type; they are never absent and follow the law of chance,
+but they do not afford the material from which to build new species. 
+Mutations, on the other hand, only happen to occur from time to time.  They
+do not necessarily produce greater changes than fluctuations, but such as
+may become, or rather are from their very nature, constant.  It is this
+constancy which is the mark of specific characters, and on this basis every
+new specific character may be assumed to have arisen by mutation.
+
+Some authors have tried to show that the theory of mutation is opposed to
+Darwin's views.  But this is erroneous.  On the contrary, it is in fullest
+harmony with the great principle laid down by Darwin.  In order to be acted
+upon by that complex of environmental forces, which Darwin has called
+natural selection, the changes must obviously first be there.  The manner
+in which they are produced is of secondary importance and has hardly any
+bearing on the theory of descent with modification.  ("Life and Letters"
+II. 125.)
+ 
+A critical survey of all the facts of variability of plants in nature as
+well as under cultivation has led me to the conviction, that Darwin was
+right in stating that those rare beneficial variations, which from time to
+time happen to arise,--the now so-called mutations--are the real source of
+progress in the whole realm of the organic world.
+
+II.  EXTERNAL AND INTERNAL CAUSES OF VARIABILITY.
+
+All phenomena of animal and plant life are governed by two sets of causes;
+one of these is external, the other internal.  As a rule the internal
+causes determine the nature of a phenomenon--what an organism can do and
+what it cannot do.  The external causes, on the other hand, decide when a
+certain variation will occur, and to what extent its features may be
+developed.
+
+As a very clear and wholly typical instance I cite the cocks-combs
+(Celosia).  This race is distinguished from allied forms by its faculty of
+producing the well-known broad and much twisted combs.  Every single
+individual possesses this power, but all individuals do not exhibit it in
+its most complete form.  In some cases this faculty may not be exhibited at
+the top of the main stem, although developed in lateral branches:  in
+others it begins too late for full development.  Much depends upon
+nourishment and cultivation, but almost always the horticulturist has to
+single out the best individuals and to reject those which do not come up to
+the standard.
+
+The internal causes are of a historical nature.  The external ones may be
+defined as nourishment and environment.  In some cases nutrition is the
+main factor, as, for instance, in fluctuating variability, but in natural
+selection environment usually plays the larger part.
+
+The internal or historical causes are constant during the life-time of a
+species, using the term species in its most limited sense, as designating
+the so-called elementary species or the units out of which the ordinary
+species are built up.  These historical causes are simply the specific
+characters, since in the origin of a species one or more of these must have
+been changed, thus producing the characters of the new type.  These changes
+must, of course, also be due partly to internal and partly to external
+causes.
+
+In contrast to these changes of the internal causes, the ordinary
+variability which is exhibited during the life-time of a species is called
+fluctuating variability.  The name mutations or mutating variability is
+then given to the changes in the specific characters.  It is desirable to
+consider these two main divisions of variability separately.
+
+In the case of fluctuations the internal causes, as well as the external
+ones, are often apparent.  The specific characters may be designated as the
+mean about which the observed forms vary.  Almost every character may be
+developed to a greater or a less degree, but the variations of the single
+characters producing a small deviation from the mean are usually the
+commonest.  The limits of these fluctuations may be called wide or narrow,
+according to the way we look at them, but in numerous cases the extreme on
+the favoured side hardly surpasses double the value of that on the other
+side.  The degree of this development, for every individual and for every
+organ, is dependent mainly on nutrition.  Better nourishment or an
+increased supply of food produces a higher development; only it is not
+always easy to determine which direction is the fuller and which is the
+poorer one.  The differences among individuals grown from different seeds
+are described as examples of individual variability, but those which may be
+observed on the same plant, or on cuttings, bulbs or roots derived from one
+individual are referred to as cases of partial variability.  Partial
+variability, therefore, determines the differences among the flowers,
+fruits, leaves or branches of one individual:  in the main, it follows the
+same laws as individual variability, but the position of a branch on a
+plant also determines its strength, and the part it may take in the
+nourishment of the whole.  Composite flowers and umbels therefore have, as
+a rule, fewer rays on weak branches than on the strong main ones.  The
+number of carpels in the fruits of poppies becomes very small on the weak
+lateral branches, which are produced towards the autumn, as well as on
+crowded, and therefore on weakened individuals.  Double flowers follow the
+same rule, and numerous other instances could easily be adduced.
+
+Mutating variability occurs along three main lines.  Either a character may
+disappear, or, as we now say, become latent; or a latent character may
+reappear, reproducing thereby a character which was once prominent in more
+or less remote ancestors.  The third and most interesting case is that of
+the production of quite new characters which never existed in the
+ancestors.  Upon this progressive mutability the main development of the
+animal and vegetable kingdom evidently depends.  In contrast to this, the
+two other cases are called retrogressive and degressive mutability.  In
+nature retrogressive mutability plays a large part; in agriculture and in
+horticulture it gives rise to numerous varieties, which have in the past
+been preserved, either on account of their usefulness or beauty, or simply
+as fancy-types.  In fact the possession of numbers of varieties may be
+considered as the main character of domesticated animals and cultivated
+plants.
+
+In the case of retrogressive and degressive mutability the internal cause
+is at once apparent, for it is this which causes the disappearance or
+reappearance of some character.  With progressive mutations the case is not
+so simple, since the new character must first be produced and then
+displayed.  These two processes are theoretically different, but they may
+occur together or after long intervals.  The production of the new
+character I call premutation, and the displaying mutation.  Both of course
+must have their external as well as their internal causes, as I have
+repeatedly pointed out in my work on the Mutation Theory.  ("Die
+Mutationstheorie", 2 vols., Leipzig, 1901.)
+
+It is probable that nutrition plays as important a part among the external
+causes of mutability as it does among those of fluctuating variability. 
+Observations in support of this view, however, are too scanty to allow of a
+definite judgment.  Darwin assumed an accumulative influence of external
+causes in the case of the production of new varieties or species.  The
+accumulation might be limited to the life-time of a single individual, or
+embrace that of two or more generations.  In the end a degree of
+instability in the equilibrium of one or more characters might be attained,
+great enough for a character to give way under a small shock produced by
+changed conditions of life.  The character would then be thrown over from
+the old state of equilibrium into a new one.
+
+Characters which happen to be in this state of unstable equilibrium are
+called mutable.  They may be either latent or active, being in the former
+case derived from old active ones or produced as new ones (by the process,
+designated premutation).  They may be inherited in this mutable condition
+during a long series of generations.  I have shown that in the case of the
+evening primrose of Lamarck this state of mutability must have existed for
+at least half a century, for this species was introduced from Texas into
+England about the year 1860, and since then all the strains derived from
+its first distribution over the several countries of Europe show the same
+phenomena in producing new forms.  The production of the dwarf evening
+primrose, or Oenothera nanella, is assumed to be due to one of the factors,
+which determines the tall stature of the parent form, becoming latent; this
+would, therefore, afford an example of retrogressive mutation.  Most of the
+other types of my new mutants, on the other hand, seem to be due to
+progressive mutability.
+
+The external causes of this curious period of mutability are as yet wholly
+unknown and can hardly be guessed at, since the origin of the Oenothera
+Lamarckiana is veiled in mystery.  The seeds, introduced into England about
+1860, were said to have come from Texas, but whether from wild or from
+cultivated plants we do not know.  Nor has the species been recorded as
+having been observed in the wild condition.  This, however, is nothing
+peculiar.  The European types of Oenothera biennis and O. muricata are in
+the same condition.  The first is said to have been introduced from
+Virginia, and the second from Canada, but both probably from plants
+cultivated in the gardens of these countries.  Whether the same elementary
+species are still growing on those spots is unknown, mainly because the
+different sub-species of the species mentioned have not been systematically
+studied and distinguished.
+
+The origin of new species, which is in part the effect of mutability, is,
+however, due mainly to natural selection.  Mutability provides the new
+characters and new elementary species.  Natural selection, on the other
+hand, decides what is to live and what to die.  Mutability seems to be
+free, and not restricted to previously determined lines.  Selection,
+however, may take place along the same main lines in the course of long
+geological epochs, thus directing the development of large branches of the
+animal and vegetable kingdom.  In natural selection it is evident that
+nutrition and environment are the main factors.  But it is probable that,
+while nutrition may be one of the main causes of mutability, environment
+may play the chief part in the decisions ascribed to natural selection. 
+Relations to neighbouring plants and to injurious or useful animals, have
+been considered the most important determining factors ever since the time
+when Darwin pointed out their prevailing influence.
+
+From this discussion of the main causes of variability we may derive the
+proposition that the study of every phenomenon in the field of heredity, of
+variability, and of the origin of new species will have to be considered
+from two standpoints; on one hand we have the internal causes, on the other
+the external ones.  Sometimes the first are more easily detected, in other
+cases the latter are more accessible to investigation.  But the complete
+elucidation of any phenomenon of life must always combine the study of the
+influence of internal with that of external causes.
+
+III.  POLYMORPHIC VARIABILITY IN CEREALS.
+
+One of the propositions of Darwin's theory of the struggle for life
+maintains that the largest amount of life can be supported on any area, by
+great diversification or divergence in the structure and constitution of
+its inhabitants.  Every meadow and every forest affords a proof of this
+thesis.  The numerical proportion of the different species of the flora is
+always changing according to external influences.  Thus, in a given meadow,
+some species will flower abundantly in one year and then almost disappear,
+until, after a series of years, circumstances allow them again to multiply
+rapidly.  Other species, which have taken their places, will then become
+rare.  It follows from this principle, that notwithstanding the constantly
+changing conditions, a suitable selection from the constituents of a meadow
+will ensure a continued high production.  But, although the principle is
+quite clear, artificial selection has, as yet, done very little towards
+reaching a really high standard.
+
+The same holds good for cereals.  In ordinary circumstances a field will
+give a greater yield, if the crop grown consists of a number of
+sufficiently differing types.  Hence it happens that almost all older
+varieties of wheat are mixtures of more or less diverging forms.  In the
+same variety the numerical composition will vary from year to year, and in
+oats this may, in bad years, go so far as to destroy more than half of the
+harvest, the wind-oats (Avena fatua), which scatter their grain to the
+winds as soon as it ripens, increasing so rapidly that they assume the
+dominant place.  A severe winter, a cold spring and other extreme
+conditions of life will destroy one form more completely than another, and
+it is evident that great changes in the numerical composition of the
+mixture may thus be brought about.
+
+This mixed condition of the common varieties of cereals was well known to
+Darwin.  For him it constituted one of the many types of variability.  It
+is of that peculiar nature to which, in describing other groups, he applies
+the term polymorphy.  It does not imply that the single constituents of the
+varieties are at present really changing their characters.  On the other
+hand, it does not exclude the possibility of such changes.  It simply
+states that observation shows the existence of different forms; how these
+have originated is a question which it does not deal with.  In his well-
+known discussion of the variability of cereals, Darwin is mainly concerned
+with the question, whether under cultivation they have undergone great
+changes or only small ones.  The decision ultimately depends on the
+question, how many forms have originally been taken into cultivation. 
+Assuming five or six initial species, the variability must be assumed to
+have been very large, but on the assumption that there were between ten and
+fifteen types, the necessary range of variability is obviously much
+smaller.  But in regard to this point, we are of course entirely without
+historical data.
+
+Few of the varieties of wheat show conspicuous differences, although their
+number is great.  If we compare the differentiating characters of the
+smaller types of cereals with those of ordinary wild species, even within
+the same genus or family, they are obviously much less marked.  All these
+small characters, however, are strictly inherited, and this fact makes it
+very probable that the less obvious constituents of the mixtures in
+ordinary fields must be constant and pure as long as they do not
+intercross.  Natural crossing is in most cereals a phenomenon of rare
+occurrence, common enough to admit of the production of all possible hybrid
+combinations, but requiring the lapse of a long series of years to reach
+its full effect.
+
+Darwin laid great stress on this high amount of variability in the plants
+of the same variety, and illustrated it by the experience of Colonel Le
+Couteur ("On the Varieties, Properties, and Classification of Wheat",
+Jersey, 1837.) on his farm on the isle of Jersey, who cultivated upwards of
+150 varieties of wheat, which he claimed were as pure as those of any other
+agriculturalist.  But Professor La Gasca of Madrid, who visited him, drew
+attention to aberrant ears, and pointed out, that some of them might be
+better yielders than the majority of plants in the crop, whilst others
+might be poor types.  Thence he concluded that the isolation of the better
+ones might be a means of increasing his crops.  Le Couteur seems to have
+considered the constancy of such smaller types after isolation as
+absolutely probable, since he did not even discuss the possibility of their
+being variable or of their yielding a changeable or mixed progeny.  This
+curious fact proves that he considered the types, discovered in his fields
+by La Gasca to be of the same kind as his other varieties, which until that
+time he had relied upon as being pure and uniform.  Thus we see, that for
+him, the variability of cereals was what we now call polymorphy.  He looked
+through his fields for useful aberrations, and collected twenty-three new
+types of wheat.  He was, moreover, clear about one point, which, on being
+rediscovered after half a century, has become the starting-point for the
+new Swedish principle of selecting agricultural plants.  It was the
+principle of single-ear sowing, instead of mixing the grains of all the
+selected ears together.  By sowing each ear on a separate plot he intended
+not only to multiply them, but also to compare their value.  This
+comparison ultimately led him to the choice of some few valuable sorts, one
+of which, the "Bellevue de Talavera," still holds its place among the
+prominent sorts of wheat cultivated in France.  This variety seems to be
+really a uniform type, a quality very useful under favourable conditions of
+cultivation, but which seems to have destroyed its capacity for further
+improvement by selection.
+
+The principle of single-ear sowing, with a view to obtain pure and uniform
+strains without further selection, has, until a few years ago, been almost
+entirely lost sight of.  Only a very few agriculturists have applied it: 
+among these are Patrick Shirreff ("Die Verbesserung der Getreide-Arten",
+translated by R. Hesse, Halle, 1880.) in Scotland and Willet M. Hays
+("Wheat, varieties, breeding, cultivation", Univ. Minnesota, Agricultural
+Experimental Station, Bull. no. 62, 1899.) in Minnesota.  Patrick Shirreff
+observed the fact, that in large fields of cereals, single plants may from
+time to time be found with larger ears, which justify the expectation of a
+far greater yield.  In the course of about twenty-five years he isolated in
+this way two varieties of wheat and two of oats.  He simply multiplied them
+as fast as possible, without any selection, and put them on the market.
+
+Hays was struck by the fact that the yield of wheat in Minnesota was far
+beneath that in the neighbouring States.  The local varieties were Fife and
+Blue Stem.  They gave him, on inspection, some better specimens,
+"phenomenal yielders" as he called them.  These were simply isolated and
+propagated, and, after comparison with the parent-variety and with some
+other selected strains of less value, were judged to be of sufficient
+importance to be tested by cultivation all over the State of Minnesota. 
+They have since almost supplanted the original types, at least in most
+parts of the State, with the result that the total yield of wheat in
+Minnesota is said to have been increased by about a million dollars yearly.
+
+Definite progress in the method of single-ear sowing has, however, been
+made only recently.  It had been foreshadowed by Patrick Shirreff, who
+after the production of the four varieties already mentioned, tried to
+carry out his work on a larger scale, by including numerous minor
+deviations from the main type.  He found by doing so that the chances of
+obtaining a better form were sufficiently increased to justify the trial. 
+But it was Nilsson who discovered the almost inexhaustible polymorphy of
+cereals and other agricultural crops and made it the starting-point for a
+new and entirely trustworthy method of the highest utility.  By this means
+he has produced during the last fifteen years a number of new and valuable
+races, which have already supplanted the old types on numerous farms in
+Sweden and which are now being introduced on a large scale into Germany and
+other European countries.
+
+It is now twenty years since the station at Svalof was founded.  During the
+first period of its work, embracing about five years, selection was
+practised on the principle which was then generally used in Germany.  In
+order to improve a race a sample of the best ears was carefully selected
+from the best fields of the variety.  These ears were considered as
+representatives of the type under cultivation, and it was assumed that by
+sowing their grains on a small plot a family could be obtained, which could
+afterwards be improved by a continuous selection.  Differences between the
+collected ears were either not observed or disregarded.  At Svalof this
+method of selection was practised on a far larger scale than on any German
+farm, and the result was, broadly speaking, the same.  This may be stated
+in the following words:  improvement in a few cases, failure in all the
+others.  Some few varieties could be improved and yielded excellent new
+types, some of which have since been introduced into Swedish agriculture
+and are now prominent races in the southern and middle parts of the
+country.  But the station had definite aims, and among them was the
+improvement of the Chevalier barley.  This, in Middle Sweden, is a fine
+brewer's barley, but liable to failure during unfavourable summers on
+account of its slender stems.  It was selected with a view of giving it
+stiffer stems, but in spite of all the care and work bestowed upon it no
+satisfactory result was obtained.
+
+This experience, combined with a number of analogous failures, could not
+fail to throw doubt upon the whole method.  It was evident that good
+results were only exceptions, and that in most cases the principle was not
+one that could be relied upon.  The exceptions might be due to unknown
+causes, and not to the validity of the method; it became therefore of much
+more interest to search for the causes than to continue the work along
+these lines.
+
+In the year 1892 a number of different varieties of cereals were cultivated
+on a large scale and a selection was again made from them.  About two
+hundred samples of ears were chosen, each apparently constituting a
+different type.  Their seeds were sown on separate plots and manured and
+treated as much as possible in the same manner.  The plots were small and
+arranged in rows so as to facilitate the comparison of allied types. 
+During the whole period of growth and during the ripening of the ears the
+plots were carefully studied and compared:  they were harvested separately;
+ears and kernels were counted and weighed, and notes were made concerning
+layering, rust and other cereal pests.
+
+The result of this experiment was, in the main, no distinct improvement. 
+Nilsson was especially struck by the fact that the plots, which should
+represent distinct types, were far from uniform.  Many of them were as
+multiform as the fields from which the parent-ears were taken.  Others
+showed variability in a less degree, but in almost all of them it was clear
+that a pure race had not been obtained.  The experiment was a fair one,
+inasmuch as it demonstrated the polymorphic variability of cereals beyond
+all doubt and in a degree hitherto unsuspected; but from the standpoint of
+the selectionist it was a failure.  Fortunately there were, however, one or
+two exceptions.  A few lots showed a perfect uniformity in regard to all
+the stalks and ears:  these were small families.  This fact suggested the
+idea that each might have been derived from a single ear.  During the
+selection in the previous summer, Nilsson had tried to find as many ears as
+possible of each new type which he recognised in his fields.  But the
+variability of his crops was so great, that he was rarely able to include
+more than two or three ears in the same group, and, in a few cases, he
+found only one representative of the supposed type.  It might, therefore,
+be possible that those small uniform plots were the direct progeny of ears,
+the grains of which had not been mixed with those from other ears before
+sowing.  Exact records had, of course, been kept of the chosen samples, and
+the number of ears had been noted in each case.  It was, therefore,
+possible to answer the question and it was found that those plots alone
+were uniform on which the kernels of one single ear only had been sown. 
+Nilsson concluded that the mixture of two or more ears in a single sowing
+might be the cause of the lack of uniformity in the progeny.  Apparently
+similar ears might be different in their progeny.
+
+Once discovered, this fact was elevated to the rank of a leading principle
+and tested on as large a scale as possible.  The fields were again
+carefully investigated and every single ear, which showed a distinct
+divergence from the main type in one character or another, was selected.  A
+thousand samples were chosen, but this time each sample consisted of one
+ear only.  Next year, the result corresponded to the expectation. 
+Uniformity prevailed almost everywhere; only a few lots showed a
+discrepancy, which might be ascribed to the accidental selection of hybrid
+ears.  It was now clear that the progeny of single ears was, as a rule,
+pure, whereas that of mixed ears was impure.  The single-ear selection or
+single-ear sowing, which had fallen into discredit in Germany and elsewhere
+in Europe, was rediscovered.  It proved to be the only trustworthy
+principle of selection.  Once isolated, such single-parent races are
+constant from seed and remain true to their type.  No further selection is
+needed; they have simply to be multiplied and their real value tested.
+
+Patrick Shirreff, in his early experiments, Le Couteur, Hays and others had
+observed the rare occurrence of exceptionally good yielders and the value
+of their isolation to the agriculturist.  The possibility of error in the
+choice of such striking specimens and the necessity of judging their value
+by their progeny were also known to these investigators, but they had not
+the slightest idea of all the possibilities suggested by their principle. 
+Nilsson, who is a botanist as well as an agriculturist, discovered that,
+besides these exceptionably good yielders, every variety of a cereal
+consists of hundreds of different types, which find the best conditions for
+success when grown together, but which, after isolation, prove to be
+constant.  Their preference for mixed growth is so definite, that once
+isolated, their claims on manure and treatment are found to be much higher
+than those of the original mixed variety.  Moreover, the greatest care is
+necessary to enable them to retain their purity, and as soon as they are
+left to themselves they begin to deteriorate through accidental crosses and
+admixtures and rapidly return to the mixed condition.
+
+Reverting now to Darwin's discussion of the variability of cereals, we may
+conclude that subsequent investigation has proved it to be exactly of the
+kind which he describes.  The only difference is that in reality it reaches
+a degree, quite unexpected by Darwin and his contemporaries.  But it is
+polymorphic variability in the strictest sense of the word.  How the single
+constituents of a variety originate we do not see.  We may assume, and
+there can hardly be a doubt about the truth of the assumption, that a new
+character, once produced, will slowly but surely be combined through
+accidental crosses with a large number of previously existing types, and so
+will tend to double the number of the constituents of the variety.  But
+whether it first appears suddenly or whether it is only slowly evolved we
+cannot determine.  It would, of course, be impossible to observe either
+process in such a mixture.  Only cultures of pure races, of single-parent
+races as we have called them, can afford an opportunity for this kind of
+observation.  In the fields of Svalof new and unexpected qualities have
+recently been seen, from time to time, to appear suddenly.  These
+characters are as distinct as the older ones and appear to be constant from
+the moment of their origin.
+
+Darwin has repeatedly insisted that man does not cause variability.  He
+simply selects the variations given to him by the hand of nature.  He may
+repeat this process in order to accumulate different new characters in the
+same family, thus producing varieties of a higher order.  This process of
+accumulation would, if continued for a longer time, lead to the
+augmentation of the slight differences characteristic of varieties into the
+greater differences characteristic of species and genera.  It is in this
+way that horticultural and agricultural experience contribute to the
+problem of the conversion of varieties into species, and to the explanation
+of the admirable adaptations of each organism to its complex conditions of
+life.  In the long run new forms, distinguished from their allies by quite
+a number of new characters, would, by the extermination of the older
+intermediates, become distinct species.
+
+Thus we see that the theory of the origin of species by means of natural
+selection is quite independent of the question, how the variations to be
+selected arise.  They may arise slowly, from simple fluctuations, or
+suddenly, by mutations; in both cases natural selection will take hold of
+them, will multiply them if they are beneficial, and in the course of time
+accumulate them, so as to produce that great diversity of organic life,
+which we so highly admire.
+
+Darwin has left the decision of this difficult and obviously subordinate
+point to his followers.  But in his Pangenesis hypothesis he has given us
+the clue for a close study and ultimate elucidation of the subject under
+discussion.
+
+
+V.  HEREDITY AND VARIATION IN MODERN LIGHTS.
+
+By W. BATESON, M.A., F.R.S.
+
+Professor of Biology in the University of Cambridge.
+
+Darwin's work has the property of greatness in that it may be admired from
+more aspects than one.  For some the perception of the principle of Natural
+Selection stands out as his most wonderful achievement to which all the
+rest is subordinate.  Others, among whom I would range myself, look up to
+him rather as the first who plainly distinguished, collected, and
+comprehensively studied that new class of evidence from which hereafter a
+true understanding of the process of Evolution may be developed.  We each
+prefer our own standpoint of admiration; but I think that it will be in
+their wider aspect that his labours will most command the veneration of
+posterity.
+
+A treatise written to advance knowledge may be read in two moods.  The
+reader may keep his mind passive, willing merely to receive the impress of
+the writer's thought; or he may read with his attention strained and alert,
+asking at every instant how the new knowledge can be used in a further
+advance, watching continually for fresh footholds by which to climb higher
+still.  Of Shelley it has been said that he was a poet for poets:  so
+Darwin was a naturalist for naturalists.  It is when his writings are used
+in the critical and more exacting spirit with which we test the outfit for
+our own enterprise that we learn their full value and strength.  Whether we
+glance back and compare his performance with the efforts of his
+predecessors, or look forward along the course which modern research is
+disclosing, we shall honour most in him not the rounded merit of finite
+accomplishment, but the creative power by which he inaugurated a line of
+discovery endless in variety and extension.  Let us attempt thus to see his
+work in true perspective between the past from which it grew, and the
+present which is its consequence.  Darwin attacked the problem of Evolution
+by reference to facts of three classes:  Variation; Heredity; Natural
+Selection.  His work was not as the laity suppose, a sudden and unheralded
+revelation, but the first fruit of a long and hitherto barren controversy.
+The occurrence of variation from type, and the hereditary transmission of
+such variation had of course been long familiar to practical men, and
+inferences as to the possible bearing of those phenomena on the nature of
+specific difference had been from time to time drawn by naturalists. 
+Maupertuis, for example, wrote "Ce qui nous reste a examiner, c'est comment
+d'un seul individu, il a pu naitre tant d'especes si differentes."  And
+again "La Nature contient le fonds de toutes ces varietes:  mais le hasard
+ou l'art les mettent en oeuvre.  C'est ainsi que ceux dont l'industrie
+s'applique a satisfaire le gout des curieux, sont, pour ainsi dire,
+creatures d'especes nouvelles."  ("Venus Physique, contenant deux
+Dissertations, l'une sur l'origine des Hommes et des Animaux:  Et l'autre
+sur l'origine des Noirs" La Haye, 1746, pages 124 and 129.  For an
+introduction to the writings of Maupertuis I am indebted to an article by
+Professor Lovejoy in "Popular Sci. Monthly", 1902.)
+
+Such passages, of which many (though few so emphatic) can be found in
+eighteenth century writers, indicate a true perception of the mode of
+Evolution.  The speculations hinted at by Buffon (For the fullest account
+of the views of these pioneers of Evolution, see the works of Samuel
+Butler, especially "Evolution, Old and New" (2nd edition) 1882.  Butler's
+claims on behalf of Buffon have met with some acceptance; but after reading
+what Butler has said, and a considerable part of Buffon's own works, the
+word "hinted" seems to me a sufficiently correct description of the part he
+played.  It is interesting to note that in the chapter on the Ass, which
+contains some of his evolutionary passages, there is a reference to
+"plusieurs idees tres-elevees sur la generation" contained in the Letters
+of Maupertuis.), developed by Erasmus Darwin, and independently proclaimed
+above all by Lamarck, gave to the doctrine of descent a wide renown.  The
+uniformitarian teaching which Lyell deduced from geological observation had
+gained acceptance.  The facts of geographical distribution (See especially
+W. Lawrence, "Lectures on Physiology", London, 1823, pages 213 f.) had been
+shown to be obviously inconsistent with the Mosaic legend.  Prichard, and
+Lawrence, following the example of Blumenbach, had successfully
+demonstrated that the races of Man could be regarded as different forms of
+one species, contrary to the opinion up till then received.  These
+treatises all begin, it is true, with a profound obeisance to the sons of
+Noah, but that performed, they continue on strictly modern lines.  The
+question of the mutability of species was thus prominently raised.
+
+Those who rate Lamarck no higher than did Huxley in his contemptuous phrase
+"buccinator tantum," will scarcely deny that the sound of the trumpet had
+carried far, or that its note was clear.  If then there were few who had
+already turned to evolution with positive conviction, all scientific men
+must at least have known that such views had been promulgated; and many
+must, as Huxley says, have taken up his own position of "critical
+expectancy."  (See the chapter contributed to the "Life and Letters of
+Charles Darwin" II. page 195.  I do not clearly understand the sense in
+which Darwin wrote (Autobiography, ibid. I. page 87):  "It has sometimes
+been said that the success of the "Origin" proved 'that the subject was in
+the air,' or 'that men's minds were prepared for it.'  I do not think that
+this is strictly true, for I occasionally sounded not a few naturalists,
+and never happened to come across a single one who seemed to doubt about
+the permanence of species."  This experience may perhaps have been an
+accident due to Darwin's isolation.  The literature of the period abounds
+with indications of "critical expectancy."  A most interesting expression
+of that feeling is given in the charming account of the "Early Days of
+Darwinism" by Alfred Newton, "Macmillan's Magazine", LVII. 1888, page 241. 
+He tells how in 1858 when spending a dreary summer in Iceland, he and his
+friend, the ornithologist John Wolley, in default of active occupation,
+spent their days in discussion.  "Both of us taking a keen interest in
+Natural History, it was but reasonable that a question, which in those days
+was always coming up wherever two or more naturalists were gathered
+together, should be continually recurring.  That question was, 'What is a
+species?' and connected therewith was the other question, 'How did a
+species begin?'...Now we were of course fairly well acquainted with what
+had been published on these subjects."  He then enumerates some of these
+publications, mentioning among others T. Vernon Wollaston's "Variation of
+Species"--a work which has in my opinion never been adequately appreciated.
+He proceeds:  "Of course we never arrived at anything like a solution of
+these problems, general or special, but we felt very strongly that a
+solution ought to be found, and that quickly, if the study of Botany and
+Zoology was to make any great advance."  He then describes how on his
+return home he received the famous number of the "Linnean Journal" on a
+certain evening.  "I sat up late that night to read it; and never shall I
+forget the impression it made upon me.  Herein was contained a perfectly
+simple solution of all the difficulties which had been troubling me for
+months past...I went to bed satisfied that a solution had been found.")
+
+Why, then, was it, that Darwin succeeded where the rest had failed?  The
+cause of that success was two-fold.  First, and obviously, in the principle
+of Natural Selection he had a suggestion which would work.  It might not go
+the whole way, but it was true as far as it went.  Evolution could thus in
+great measure be fairly represented as a consequence of demonstrable
+processes.  Darwin seldom endangers the mechanism he devised by putting on
+it strains much greater than it can bear.  He at least was under no
+illusion as to the omnipotence of Selection; and he introduces none of the
+forced pleading which in recent years has threatened to discredit that
+principle.
+
+For example, in the latest text of the "Origin" ("Origin", (6th edition
+(1882), page 421.) we find him saying:
+
+"But as my conclusions have lately been much misrepresented, and it has
+been stated that I attribute the modification of species exclusively to
+natural selection, I may be permitted to remark that in the first edition
+of this work, and subsequently, I placed in a most conspicuous position--
+namely, at the close of the Introduction--the following words:  'I am
+convinced that natural selection has been the main but not the exclusive
+means of modification.'"
+
+But apart from the invention of this reasonable hypothesis, which may well,
+as Huxley estimated, "be the guide of biological and psychological
+speculation for the next three or four generations," Darwin made a more
+significant and imperishable contribution.  Not for a few generations, but
+through all ages he should be remembered as the first who showed clearly
+that the problems of Heredity and Variation are soluble by observation, and
+laid down the course by which we must proceed to their solution.  (Whatever
+be our estimate of the importance of Natural Selection, in this we all
+agree.  Samuel Butler, the most brilliant, and by far the most interesting
+of Darwin's opponents--whose works are at length emerging from oblivion--in
+his Preface (1882) to the 2nd edition of "Evolution, Old and New", repeats
+his earlier expression of homage to one whom he had come to regard as an
+enemy:  "To the end of time, if the question be asked, 'Who taught people
+to believe in Evolution?' the answer must be that it was Mr. Darwin.  This
+is true, and it is hard to see what palm of higher praise can be awarded to
+any philosopher.")  The moment of inspiration did not come with the reading
+of Malthus, but with the opening of the "first note-book on Transmutation
+of Species."  ("Life and Letters", I. pages 276 and 83.)  Evolution is a
+process of Variation and Heredity.  The older writers, though they had some
+vague idea that it must be so, did not study Variation and Heredity. 
+Darwin did, and so begat not a theory, but a science.
+
+The extent to which this is true, the scientific world is only beginning to
+realise.  So little was the fact appreciated in Darwin's own time that the
+success of his writings was followed by an almost total cessation of work
+in that special field.  Of the causes which led to this remarkable
+consequence I have spoken elsewhere.  They proceeded from circumstances
+peculiar to the time; but whatever the causes there is no doubt that this
+statement of the result is historically exact, and those who make it their
+business to collect facts elucidating the physiology of Heredity and
+Variation are well aware that they will find little to reward their quest
+in the leading scientific Journals of the Darwinian epoch.
+
+In those thirty years the original stock of evidence current and in
+circulation even underwent a process of attrition.  As in the story of the
+Eastern sage who first wrote the collected learning of the universe for his
+sons in a thousand volumes, and by successive compression and burning
+reduced them to one, and from this by further burning distilled the single
+ejaculation of the Faith, "There is no god but God and Mohamed is the
+Prophet of God," which was all his maturer wisdom deemed essential:--so in
+the books of that period do we find the corpus of genetic knowledge dwindle
+to a few prerogative instances, and these at last to the brief formula of
+an unquestioned creed.
+
+And yet in all else that concerns biological science this period was, in
+very truth, our Golden Age, when the natural history of the earth was
+explored as never before; morphology and embryology were exhaustively
+ransacked; the physiology of plants and animals began to rival chemistry
+and physics in precision of method and in the rapidity of its advances; and
+the foundations of pathology were laid.
+
+In contrast with this immense activity elsewhere the neglect which befel
+the special physiology of Descent, or Genetics as we now call it, is
+astonishing.  This may of course be interpreted as meaning that the
+favoured studies seemed to promise a quicker return for effort, but it
+would be more true to say that those who chose these other pursuits did so
+without making any such comparison; for the idea that the physiology of
+Heredity and Variation was a coherent science, offering possibilities of
+extraordinary discovery, was not present to their minds at all.  In a word,
+the existence of such a science was well nigh forgotten.  It is true that
+in ancillary periodicals, as for example those that treat of entomology or
+horticulture, or in the writings of the already isolated systematists (This
+isolation of the systematists is the one most melancholy sequela of
+Darwinism.  It seems an irony that we should read in the peroration to the
+"Origin" that when the Darwinian view is accepted "Systematists will be
+able to pursue their labours as at present; but they will not be
+incessantly haunted by the shadowy doubt whether this or that form be a
+true species.  This, I feel sure, and I speak after experience, will be no
+slight relief.  The endless disputes whether or not some fifty species of
+British brambles are good species will cease."  "Origin", 6th edition
+(1882), page 425.  True they have ceased to attract the attention of those
+who lead opinion, but anyone who will turn to the literature of systematics
+will find that they have not ceased in any other sense.  Should there not
+be something disquieting in the fact that among the workers who come most
+into contact with specific differences, are to be found the only men who
+have failed to be persuaded of the unreality of those differences?),
+observations with this special bearing were from time to time related, but
+the class of fact on which Darwin built his conceptions of Heredity and
+Variation was not seen in the highways of biology.  It formed no part of
+the official curriculum of biological students, and found no place among
+the subjects which their teachers were investigating.
+
+During this period nevertheless one distinct advance was made, that with
+which Weismann's name is prominently connected.  In Darwin's genetic scheme
+the hereditary transmission of parental experience and its consequences
+played a considerable role.  Exactly how great that role was supposed to
+be, he with his habitual caution refrained from specifying, for the
+sufficient reason that he did not know.  Nevertheless much of the process
+of Evolution, especially that by which organs have become degenerate and
+rudimentary, was certainly attributed by Darwin to such inheritance, though
+since belief in the inheritance of acquired characters fell into disrepute,
+the fact has been a good deal overlooked.  The "Origin" without "use and
+disuse" would be a materially different book.  A certain vacillation is
+discernible in Darwin's utterances on this question, and the fact gave to
+the astute Butler an opportunity for his most telling attack.  The
+discussion which best illustrates the genetic views of the period arose in
+regard to the production of the rudimentary condition of the wings of many
+beetles in the Madeira group of islands, and by comparing passages from the
+"Origin" (6th edition pages 109 and 401.  See Butler, "Essays on Life, Art,
+and Science", page 265, reprinted 1908, and "Evolution, Old and New",
+chapter XXII. (2nd edition), 1882.) Butler convicts Darwin of saying first
+that this condition was in the main the result of Selection, with disuse
+aiding, and in another place that the main cause of degeneration was
+disuse, but that Selection had aided.  To Darwin however I think the point
+would have seemed one of dialectics merely.  To him the one paramount
+purpose was to show that somehow an Evolution by means of Variation and
+Heredity might have brought about the facts observed, and whether they had
+come to pass in the one way or the other was a matter of subordinate
+concern.
+
+
+To us moderns the question at issue has a diminished significance.  For
+over all such debates a change has been brought by Weismann's challenge for
+evidence that use and disuse have any transmitted effects at all.  Hitherto
+the transmission of many acquired characteristics had seemed to most
+naturalists so obvious as not to call for demonstration.  (W. Lawrence was
+one of the few who consistently maintained the contrary opinion.  Prichard,
+who previously had expressed himself in the same sense, does not, I believe
+repeat these views in his later writings, and there are signs that he came
+to believe in the transmission of acquired habits.  See Lawrence, "Lect.
+Physiol." 1823, pages 436-437, 447 Prichard, Edin. Inaug. Disp. 1808 (not
+seen by me), quoted ibid. and "Nat. Hist. Man", 1843, pages 34 f.) 
+Weismann's demand for facts in support of the main proposition revealed at
+once that none having real cogency could be produced.  The time-honoured
+examples were easily shown to be capable of different explanations.  A few
+certainly remain which cannot be so summarily dismissed, but--though it is
+manifestly impossible here to do justice to such a subject--I think no one
+will dispute that these residual and doubtful phenomena, whatever be their
+true nature, are not of a kind to help us much in the interpretation of any
+of those complex cases of adaptation which on the hypothesis of unguided
+Natural Selection are especially difficult to understand.  Use and disuse
+were invoked expressly to help us over these hard places; but whatever
+changes can be induced in offspring by direct treatment of the parents,
+they are not of a kind to encourage hope of real assistance from that
+quarter.  It is not to be denied that through the collapse of this second
+line of argument the Selection hypothesis has had to take an increased and
+perilous burden.  Various ways of meeting the difficulty have been
+proposed, but these mostly resolve themselves into improbable attempts to
+expand or magnify the powers of Natural Selection.
+
+Weismann's interpellation, though negative in purpose, has had a lasting
+and beneficial effect, for through his thorough demolition of the old loose
+and distracting notions of inherited experience, the ground has been
+cleared for the construction of a true knowledge of heredity based on
+experimental fact.
+
+In another way he made a contribution of a more positive character, for his
+elaborate speculations as to the genetic meaning of cytological appearances
+have led to a minute investigation of the visible phenomena occurring in
+those divisions by which germ-cells arise.  Though the particular views he
+advocated have very largely proved incompatible with the observed facts of
+heredity, yet we must acknowledge that it was chiefly through the stimulus
+of Weismann's ideas that those advances in cytology were made; and though
+the doctrine of the continuity of germ-plasm cannot be maintained in the
+form originally propounded, it is in the main true and illuminating.  (It
+is interesting to see how nearly Butler was led by natural penetration, and
+from absolutely opposite conclusions, back to this underlying truth:  "So
+that each ovum when impregnate should be considered not as descended from
+its ancestors, but as being a continuation of the personality of every ovum
+in the chain of its ancestry, which every ovum IT ACTUALLY IS quite as
+truly as the octogenarian IS the same identity with the ovum from which he
+has been developed.  This process cannot stop short of the primordial cell,
+which again will probably turn out to be but a brief resting-place.  We
+therefore prove each one of us to BE ACTUALLY the primordial cell which
+never died nor dies, but has differentiated itself into the life of the
+world, all living beings whatever, being one with it and members one of
+another," "Life and Habit", 1878, page 86.)  Nevertheless in the present
+state of knowledge we are still as a rule quite unable to connect
+cytological appearances with any genetic consequence and save in one
+respect (obviously of extreme importance--to be spoken of later) the two
+sets of phenomena might, for all we can see, be entirely distinct.
+
+I cannot avoid attaching importance to this want of connection between the
+nuclear phenomena and the features of bodily organisation.  All attempts to
+investigate Heredity by cytological means lie under the disadvantage that
+it is the nuclear changes which can alone be effectively observed. 
+Important as they must surely be, I have never been persuaded that the rest
+of the cell counts for nothing.  What we know of the behaviour and
+variability of chromosomes seems in my opinion quite incompatible with the
+belief that they alone govern form, and are the sole agents responsible in
+heredity.  (This view is no doubt contrary to the received opinion.  I am
+however interested to see it lately maintained by Driesch ("Science and
+Philosophy of the Organism", London, 1907, page 233), and from the recent
+observations of Godlewski it has received distinct experimental support.)
+
+If, then, progress was to be made in Genetics, work of a different kind was
+required.  To learn the laws of Heredity and Variation there is no other
+way than that which Darwin himself followed, the direct examination of the
+phenomena.  A beginning could be made by collecting fortuitous observations
+of this class, which have often thrown a suggestive light, but such
+evidence can be at best but superficial and some more penetrating
+instrument of research is required.  This can only be provided by actual
+experiments in breeding.
+
+The truth of these general considerations was becoming gradually clear to
+many of us when in 1900 Mendel's work was rediscovered.  Segregation, a
+phenomenon of the utmost novelty, was thus revealed.  From that moment not
+only in the problem of the origin of species, but in all the great problems
+of biology a new era began.  So unexpected was the discovery that many
+naturalists were convinced it was untrue, and at once proclaimed Mendel's
+conclusions as either altogether mistaken, or if true, of very limited
+application.  Many fantastic notions about the workings of Heredity had
+been asserted as general principles before:  this was probably only another
+fancy of the same class.
+
+Nevertheless those who had a preliminary acquaintance with the facts of
+Variation were not wholly unprepared for some such revelation.  The
+essential deduction from the discovery of segregation was that the
+characters of living things are dependent on the presence of definite
+elements or factors, which are treated as units in the processes of
+Heredity.  These factors can thus be recombined in various ways.  They act
+sometimes separately, and sometimes they interact in conjunction with each
+other, producing their various effects.  All this indicates a definiteness
+and specific order in heredity, and therefore in variation.  This order
+cannot by the nature of the case be dependent on Natural Selection for its
+existence, but must be a consequence of the fundamental chemical and
+physical nature of living things.  The study of Variation had from the
+first shown that an orderliness of this kind was present.  The bodies and
+the properties of living things are cosmic, not chaotic.  No matter how low
+in the scale we go, never do we find the slightest hint of a diminution in
+that all-pervading orderliness, nor can we conceive an organism existing
+for a moment in any other state.  Moreover not only does this order prevail
+in normal forms, but again and again it is to be seen in newly-sprung
+varieties, which by general consent cannot have been subjected to a
+prolonged Selection.  The discovery of Mendelian elements admirably
+coincided with and at once gave a rationale of these facts.  Genetic
+Variation is then primarily the consequence of additions to, or omissions
+from, the stock of elements which the species contains.  The further
+investigation of the species-problem must thus proceed by the analytical
+method which breeding experiments provide.
+
+In the nine years which have elapsed since Mendel's clue became generally
+known, progress has been rapid.  We now understand the process by which a
+polymorphic race maintains its polymorphism.  When a family consists of
+dissimilar members, given the numerical proportions in which these members
+are occurring, we can represent their composition symbolically and state
+what types can be transmitted by the various members.  The difficulty of
+the "swamping effects of intercrossing" is practically at an end.  Even the
+famous puzzle of sex-limited inheritance is solved, at all events in its
+more regular manifestations, and we know now how it is brought about that
+the normal sisters of a colour-blind man can transmit the colour-blindness
+while his normal brothers cannot transmit it.
+
+We are still only on the fringe of the inquiry.  It can be seen extending
+and ramifying in many directions.  To enumerate these here would be
+impossible.  A whole new range of possibilities is being brought into view
+by study of the interrelations between the simple factors.  By following up
+the evidence as to segregation, indications have been obtained which can
+only be interpreted as meaning that when many factors are being
+simultaneously redistributed among the germ-cells, certain of them exert
+what must be described as a repulsion upon other factors.  We cannot
+surmise whither this discovery may lead.
+
+In the new light all the old problems wear a fresh aspect.  Upon the
+question of the nature of Sex, for example, the bearing of Mendelian
+evidence is close.  Elsewhere I have shown that from several sets of
+parallel experiments the conclusion is almost forced upon us that, in the
+types investigated, of the two sexes the female is to be regarded as
+heterozygous in sex, containing one unpaired dominant element, while the
+male is similarly homozygous in the absence of that element.  (In other
+words, the ova are each EITHER female, OR male (i.e. non-female), but the
+sperms are all non-female.)  It is not a little remarkable that on this
+point--which is the only one where observations of the nuclear processes of
+gameto-genesis have yet been brought into relation with the visible
+characteristics of the organisms themselves--there should be diametrical
+opposition between the results of breeding experiments and those derived
+from cytology.
+
+Those who have followed the researches of the American school will be aware
+that, after it had been found in certain insects that the spermatozoa were
+of two kinds according as they contained or did not contain the accessory
+chromosome, E.B. Wilson succeeded in proving that the sperms possessing
+this accessory body were destined to form FEMALES on fertilisation, while
+sperms without it form males, the eggs being apparently indifferent. 
+Perhaps the most striking of all this series of observations is that lately
+made by T.H. Morgan (Morgan, "Proc. Soc. Exp. Biol. Med." V. 1908, and von
+Baehr, "Zool. Anz." XXXII. page 507, 1908.), since confirmed by von Baehr,
+that in a Phylloxeran two kinds of spermatids are formed, respectively with
+and without an accessory (in this case, DOUBLE) chromosome.  Of these, only
+those possessing the accessory body become functional spermatozoa, the
+others degenerating.  We have thus an elucidation of the puzzling fact that
+in these forms fertilisation results in the formation of FEMALES only.  How
+the males are formed--for of course males are eventually produced by the
+parthenogenetic females--we do not know.
+
+If the accessory body is really to be regarded as bearing the factor for
+femaleness, then in Mendelian terms female is DD and male is DR.  The eggs
+are indifferent and the spermatozoa are each male, OR female.  But
+according to the evidence derived from a study of the sex-limited descent
+of certain features in other animals the conclusion seems equally clear
+that in them female must be regarded as DR and male as RR.  The eggs are
+thus each either male or female and the spermatozoa are indifferent.  How
+this contradictory evidence is to be reconciled we do not yet know.  The
+breeding work concerns fowls, canaries, and the Currant moth (Abraxas
+grossulariata).  The accessory chromosome has been now observed in most of
+the great divisions of insects (As Wilson has proved, the unpaired body is
+not a universal feature even in those orders in which it has been observed.
+Nearly allied types may differ.  In some it is altogether unpaired.  In
+others it is paired with a body of much smaller size, and by selection of
+various types all gradations can be demonstrated ranging to the condition
+in which the members of the pair are indistinguishable from each other.),
+except, as it happens, Lepidoptera.  At first sight it seems difficult to
+suppose that a feature apparently so fundamental as sex should be
+differently constituted in different animals, but that seems at present the
+least improbable inference.  I mention these two groups of facts as
+illustrating the nature and methods of modern genetic work.  We must
+proceed by minute and specific analytical investigation.  Wherever we look
+we find traces of the operation of precise and specific rules.
+
+In the light of present knowledge it is evident that before we can attack
+the Species-problem with any hope of success there are vast arrears to be
+made up.  He would be a bold man who would now assert that there was no
+sense in which the term Species might not have a strict and concrete
+meaning in contradistinction to the term Variety.  We have been taught to
+regard the difference between species and variety as one of degree.  I
+think it unlikely that this conclusion will bear the test of further
+research.  To Darwin the question, What is a variation? presented no
+difficulties.  Any difference between parent and offspring was a variation.
+Now we have to be more precise.  First we must, as de Vries has shown,
+distinguish real, genetic, variation from FLUCTUATIONAL variations, due to
+environmental and other accidents, which cannot be transmitted.  Having
+excluded these sources of error the variations observed must be expressed
+in terms of the factors to which they are due before their significance can
+be understood.  For example, numbers of the variations seen under
+domestication, and not a few witnessed in nature, are simply the
+consequence of some ingredient being in an unknown way omitted from the
+composition of the varying individual.  The variation may on the contrary
+be due to the addition of some new element, but to prove that it is so is
+by no means an easy matter.  Casual observation is useless, for though
+these latter variations will always be dominants, yet many dominant
+characteristics may arise from another cause, namely the meeting of
+complementary factors, and special study of each case in two generations at
+least is needed before these two phenomena can be distinguished.
+
+When such considerations are fully appreciated it will be realised that
+medleys of most dissimilar occurrences are all confused together under the
+term Variation.  One of the first objects of genetic analysis is to
+disentangle this mass of confusion.
+
+To those who have made no study of heredity it sometimes appears that the
+question of the effect of conditions in causing variation is one which we
+should immediately investigate, but a little thought will show that before
+any critical inquiry into such possibilities can be attempted, a knowledge
+of the working of heredity under conditions as far as possible uniform must
+be obtained.  At the time when Darwin was writing, if a plant brought into
+cultivation gave off an albino variety, such an event was without
+hesitation ascribed to the change of life.  Now we see that albino GAMETES,
+germs, that is to say, which are destitute of the pigment-forming factor,
+may have been originally produced by individuals standing an indefinite
+number of generations back in the ancestry of the actual albino, and it is
+indeed almost certain that the variation to which the appearance of the
+albino is due cannot have taken place in a generation later than that of
+the grandparents.  It is true that when a new DOMINANT appears we should
+feel greater confidence that we were witnessing the original variation, but
+such events are of extreme rarity, and no such case has come under the
+notice of an experimenter in modern times, as far as I am aware.  That they
+must have appeared is clear enough.  Nothing corresponding to the Brown-
+breasted Game fowl is known wild, yet that colour is a most definite
+dominant, and at some moment since Gallus bankiva was domesticated, the
+element on which that special colour depends must have at least once been
+formed in the germ-cell of a fowl; but we need harder evidence than any
+which has yet been produced before we can declare that this novelty came
+through over-feeding, or change of climate, or any other disturbance
+consequent on domestication.  When we reflect on the intricacies of genetic
+problems as we must now conceive them there come moments when we feel
+almost thankful that the Mendelian principles were unknown to Darwin.  The
+time called for a bold pronouncement, and he made it, to our lasting profit
+and delight.  With fuller knowledge we pass once more into a period of
+cautious expectation and reserve.
+
+In every arduous enterprise it is pleasanter to look back at difficulties
+overcome than forward to those which still seem insurmountable, but in the
+next stage there is nothing to be gained by disguising the fact that the
+attributes of living things are not what we used to suppose.  If they are
+more complex in the sense that the properties they display are throughout
+so regular (I have in view, for example, the marvellous and specific
+phenomena of regeneration, and those discovered by the students of
+"Entwicklungsmechanik".  The circumstances of its occurrence here preclude
+any suggestion that this regularity has been brought about by the workings
+of Selection.  The attempts thus to represent the phenomena have resulted
+in mere parodies of scientific reasoning.) that the Selection of minute
+random variations is an unacceptable account of the origin of their
+diversity, yet by virtue of that very regularity the problem is limited in
+scope and thus simplified.
+
+To begin with, we must relegate Selection to its proper place.  Selection
+permits the viable to continue and decides that the non-viable shall
+perish; just as the temperature of our atmosphere decides that no liquid
+carbon shall be found on the face of the earth:  but we do not suppose that
+the form of the diamond has been gradually achieved by a process of
+Selection.  So again, as the course of descent branches in the successive
+generations, Selection determines along which branch Evolution shall
+proceed, but it does not decide what novelties that branch shall bring
+forth.  "La Nature contient le fonds de toutes ces varietes, mais le hazard
+ou l'art les mettent en oeuvre," as Maupertuis most truly said.
+
+Not till knowledge of the genetic properties of organisms has attained to
+far greater completeness can evolutionary speculations have more than a
+suggestive value.  By genetic experiment, cytology and physiological
+chemistry aiding, we may hope to acquire such knowledge.  In 1872 Nathusius
+wrote ("Vortrage uber Viehzucht und Rassenerkenntniss", page 120, Berlin,
+1872.):  "Das Gesetz der Vererbung ist noch nicht erkannt; der Apfel ist
+noch nicht vom Baum der Erkenntniss gefallen, welcher, der Sage nach,
+Newton auf den rechten Weg zur Ergrundung der Gravitationsgesetze fuhrte." 
+We cannot pretend that the words are not still true, but in Mendelian
+analysis the seeds of that apple-tree at last are sown.
+
+If we were asked what discovery would do most to forward our inquiry, what
+one bit of knowledge would more than any other illuminate the problem, I
+think we may give the answer without hesitation.  The greatest advance that
+we can foresee will be made when it is found possible to connect the
+geometrical phenomena of development with the chemical.  The geometrical
+symmetry of living things is the key to a knowledge of their regularity,
+and the forces which cause it.  In the symmetry of the dividing cell the
+basis of that resemblance we call Heredity is contained.  To imitate the
+morphological phenomena of life we have to devise a system which can
+divide.  It must be able to divide, and to segment as--grossly--a vibrating
+plate or rod does, or as an icicle can do as it becomes ribbed in a
+continuous stream of water; but with this distinction, that the
+distribution of chemical differences and properties must simultaneously be
+decided and disposed in orderly relation to the pattern of the
+segmentation.  Even if a model which would do this could be constructed it
+might prove to be a useful beginning.
+
+This may be looking too far ahead.  If we had to choose some one piece of
+more proximate knowledge which we would more especially like to acquire, I
+suppose we should ask for the secret of interracial sterility.  Nothing has
+yet been discovered to remove the grave difficulty, by which Huxley in
+particular was so much oppressed, that among the many varieties produced
+under domestication--which we all regard as analogous to the species seen
+in nature--no clear case of interracial sterility has been demonstrated. 
+The phenomenon is probably the only one to which the domesticated products
+seem to afford no parallel.  No solution of the difficulty can be offered
+which has positive value, but it is perhaps worth considering the facts in
+the light of modern ideas.  It should be observed that we are not
+discussing incompatibility of two species to produce offspring (a totally
+distinct phenomenon), but the sterility of the offspring which many of them
+do produce.
+
+When two species, both perfectly fertile severally, produce on crossing a
+sterile progeny, there is a presumption that the sterility is due to the
+development in the hybrid of some substance which can only be formed by the
+meeting of two complementary factors.  That some such account is correct in
+essence may be inferred from the well-known observation that if the hybrid
+is not totally sterile but only partially so, and thus is able to form some
+good germ-cells which develop into new individuals, the sterility of these
+daughter-individuals is sensibly reduced or may be entirely absent.  The
+fertility once re-established, the sterility does not return in the later
+progeny, a fact strongly suggestive of segregation.  Now if the sterility
+of the cross-bred be really the consequence of the meeting of two
+complementary factors, we see that the phenomenon could only be produced
+among the divergent offspring of one species by the acquisition of at least
+TWO new factors; for if the acquisition of a single factor caused sterility
+the line would then end.  Moreover each factor must be separately acquired
+by distinct individuals, for if both were present together, the possessors
+would by hypothesis be sterile.  And in order to imitate the case of
+species each of these factors must be acquired by distinct breeds.  The
+factors need not, and probably would not, produce any other perceptible
+effects; they might, like the colour-factors present in white flowers, make
+no difference in the form or other characters.  Not till the cross was
+actually made between the two complementary individuals would either factor
+come into play, and the effects even then might be unobserved until an
+attempt was made to breed from the cross-bred.
+
+Next, if the factors responsible for sterility were acquired, they would in
+all probability be peculiar to certain individuals and would not readily be
+distributed to the whole breed.  Any member of the breed also into which
+BOTH the factors were introduced would drop out of the pedigree by virtue
+of its sterility.  Hence the evidence that the various domesticated breeds
+say of dogs or fowls can when mated together produce fertile offspring, is
+beside the mark.  The real question is, Do they ever produce sterile
+offspring?  I think the evidence is clearly that sometimes they do, oftener
+perhaps than is commonly supposed.  These suggestions are quite amenable to
+experimental tests.  The most obvious way to begin is to get a pair of
+parents which are known to have had any sterile offspring, and to find the
+proportions in which these steriles were produced.  If, as I anticipate,
+these proportions are found to be definite, the rest is simple.
+
+In passing, certain other considerations may be referred to.  First, that
+there are observations favouring the view that the production of totally
+sterile cross-breds is seldom a universal property of two species, and that
+it may be a matter of individuals, which is just what on the view here
+proposed would be expected.  Moreover, as we all know now, though
+incompatibility may be dependent to some extent on the degree to which the
+species are dissimilar, no such principle can be demonstrated to determine
+sterility or fertility in general.  For example, though all our Finches can
+breed together, the hybrids are all sterile.  Of Ducks some species can
+breed together without producing the slightest sterility; others have
+totally sterile offspring, and so on.  The hybrids between several genera
+of Orchids are perfectly fertile on the female side, and some on the male
+side also, but the hybrids produced between the Turnip (Brassica napus) and
+the Swede (Brassica campestris), which, according to our estimates of
+affinity should be nearly allied forms, are totally sterile.  (See Sutton,
+A.W., "Journ. Linn. Soc." XXXVIII. page 341, 1908.)  Lastly, it may be
+recalled that in sterility we are almost certainly considering a meristic
+phenomenon.  FAILURE TO DIVIDE is, we may feel fairly sure, the immediate
+"cause" of the sterility.  Now, though we know very little about the
+heredity of meristic differences, all that we do know points to the
+conclusion that the less-divided is dominant to the more-divided, and we
+are thus justified in supposing that there are factors which can arrest or
+prevent cell-division.  My conjecture therefore is that in the case of
+sterility of cross-breds we see the effect produced by a complementary pair
+of such factors.  This and many similar problems are now open to our
+analysis.
+
+The question is sometimes asked, Do the new lights on Variation and
+Heredity make the process of Evolution easier to understand?  On the whole
+the answer may be given that they do.  There is some appearance of loss of
+simplicity, but the gain is real.  As was said above, the time is not ripe
+for the discussion of the origin of species.  With faith in Evolution
+unshaken--if indeed the word faith can be used in application to that which
+is certain--we look on the manner and causation of adapted differentiation
+as still wholly mysterious.  As Samuel Butler so truly said:  "To me it
+seems that the 'Origin of Variation,' whatever it is, is the only true
+'Origin of Species'" ("Life and Habit", London, page 263, 1878.), and of
+that Origin not one of us knows anything.  But given Variation--and it is
+given:  assuming further that the variations are not guided into paths of
+adaptation--and both to the Darwinian and to the modern school this
+hypothesis appears to be sound if unproven--an evolution of species
+proceeding by definite steps is more, rather than less, easy to imagine
+than an evolution proceeding by the accumulation of indefinite and
+insensible steps.  Those who have lost themselves in contemplating the
+miracles of Adaptation (whether real or spurious) have not unnaturally
+fixed their hopes rather on the indefinite than on the definite changes. 
+The reasons are obvious.  By suggesting that the steps through which an
+adaptative mechanism arose were indefinite and insensible, all further
+trouble is spared.  While it could be said that species arise by an
+insensible and imperceptible process of variation, there was clearly no use
+in tiring ourselves by trying to perceive that process.  This labour-saving
+counsel found great favour.  All that had to be done to develop evolution-
+theory was to discover the good in everything, a task which, in the
+complete absence of any control or test whereby to check the truth of the
+discovery, is not very onerous.  The doctrine "que tout est au mieux" was
+therefore preached with fresh vigour, and examples of that illuminating
+principle were discovered with a facility that Pangloss himself might have
+envied, till at last even the spectators wearied of such dazzling
+performances.
+
+But in all seriousness, why should indefinite and unlimited variation have
+been regarded as a more probable account of the origin of Adaptation? 
+Only, I think, because the obstacle was shifted one plane back, and so
+looked rather less prominent.  The abundance of Adaptation, we all grant,
+is an immense, almost an unsurpassable difficulty in all non-Lamarckian
+views of Evolution; but if the steps by which that adaptation arose were
+fortuitous, to imagine them insensible is assuredly no help.  In one most
+important respect indeed, as has often been observed, it is a
+multiplication of troubles.  For the smaller the steps, the less could
+Natural Selection act upon them.  Definite variations--and of the
+occurrence of definite variations in abundance we have now the most
+convincing proof--have at least the obvious merit that they can make and
+often do make a real difference in the chances of life.
+
+There is another aspect of the Adaptation problem to which I can only
+allude very briefly.  May not our present ideas of the universality and
+precision of Adaptation be greatly exaggerated?  The fit of organism to its
+environment is not after all so very close--a proposition unwelcome
+perhaps, but one which could be illustrated by very copious evidence. 
+Natural Selection is stern, but she has her tolerant moods.
+
+We have now most certain and irrefragable proof that much definiteness
+exists in living things apart from Selection, and also much that may very
+well have been preserved and so in a sense constituted by Selection.  Here
+the matter is likely to rest.  There is a passage in the sixth edition of
+the "Origin" which has I think been overlooked.  On page 70 Darwin says
+"The tuft of hair on the breast of the wild turkey-cock cannot be of any
+use, and it is doubtful whether it can be ornamental in the eyes of the
+female bird."  This tuft of hair is a most definite and unusual structure,
+and I am afraid that the remark that it "cannot be of any use" may have
+been made inadvertently; but it may have been intended, for in the first
+edition the usual qualification was given and must therefore have been
+deliberately excised.  Anyhow I should like to think that Darwin did throw
+over that tuft of hair, and that he felt relief when he had done so. 
+Whether however we have his great authority for such a course or not, I
+feel quite sure that we shall be rightly interpreting the facts of nature
+if we cease to expect to find purposefulness wherever we meet with definite
+structures or patterns.  Such things are, as often as not, I suspect rather
+of the nature of tool-marks, mere incidents of manufacture, benefiting
+their possessor not more than the wire-marks in a sheet of paper, or the
+ribbing on the bottom of an oriental plate renders those objects more
+attractive in our eyes.
+
+If Variation may be in any way definite, the question once more arises, may
+it not be definite in direction?  The belief that it is has had many
+supporters, from Lamarck onwards, who held that it was guided by need, and
+others who, like Nageli, while laying no emphasis on need, yet were
+convinced that there was guidance of some kind.  The latter view under the
+name of "Orthogenesis," devised I believe by Eimer, at the present day
+commends itself to some naturalists.  The objection to such a suggestion is
+of course that no fragment of real evidence can be produced in its support. 
+On the other hand, with the experimental proof that variation consists
+largely in the unpacking and repacking of an original complexity, it is not
+so certain as we might like to think that the order of these events is not
+pre-determined.  For instance the original "pack" may have been made in
+such a way that at the nth division of the germ-cells of a Sweet Pea a
+colour-factor might be dropped, and that at the n plus n prime division the
+hooded variety be given off, and so on.  I see no ground whatever for
+holding such a view, but in fairness the possibility should not be
+forgotten, and in the light of modern research it scarcely looks so
+absurdly improbable as before.
+
+No one can survey the work of recent years without perceiving that
+evolutionary orthodoxy developed too fast, and that a great deal has got to
+come down; but this satisfaction at least remains, that in the experimental
+methods which Mendel inaugurated, we have means of reaching certainty in
+regard to the physiology of Heredity and Variation upon which a more
+lasting structure may be built.
+
+
+VI.  THE MINUTE STRUCTURE OF CELLS IN RELATION TO HEREDITY.
+
+By EDUARD STRASBURGER,
+Professor of Botany in the University of Bonn.
+
+Since 1875 an unexpected insight has been gained into the internal
+structure of cells.  Those who are familiar with the results of
+investigations in this branch of Science are convinced that any modern
+theory of heredity must rest on a basis of cytology and cannot be at
+variance with cytological facts.  Many histological discoveries, both such
+as have been proved correct and others which may be accepted as probably
+well founded, have acquired a fundamental importance from the point of view
+of the problems of heredity.
+
+My aim is to describe the present position of our knowledge of Cytology. 
+The account must be confined to essentials and cannot deal with far-
+reaching and controversial questions.  In cases where difference of opinion
+exists, I adopt my own view for which I hold myself responsible.  I hope to
+succeed in making myself intelligible even without the aid of
+illustrations:  in order to convey to the uninitiated an adequate idea of
+the phenomena connected with the life of a cell, a greater number of
+figures would be required than could be included within the scope of this
+article.
+
+So long as the most eminent investigators (As for example the illustrious
+Wilhelm Hofmeister in his "Lehre von der Pflanzenzelle" (1867).) believed
+that the nucleus of a cell was destroyed in the course of each division and
+that the nuclei of the daughter-cells were produced de novo, theories of
+heredity were able to dispense with the nucleus.  If they sought, as did
+Charles Darwin, who showed a correct grasp of the problem in the
+enunciation of his Pangenesis hypothesis, for histological connecting
+links, their hypotheses, or at least the best of them, had reference to the
+cell as a whole.  It was known to Darwin that the cell multiplied by
+division and was derived from a similar pre-existing cell.  Towards 1870 it
+was first demonstrated that cell-nuclei do not arise de novo, but are
+invariably the result of division of pre-existing nuclei.  Better methods
+of investigation rendered possible a deeper insight into the phenomena
+accompanying cell and nuclear divisions and at the same time disclosed the
+existence of remarkable structures.  The work of O. Butschli, O. Hertwig,
+W. Flemming H. Fol and of the author of this article (For further reference
+to literature, see my article on "Die Ontogenie der Zelle seit 1875", in
+the "Progressus Rei Botanicae", Vol. I. page 1, Jena, 1907.), have
+furnished conclusive evidence in favour of these facts.  It was found that
+when the reticular framework of a nucleus prepares to divide, it separates
+into single segments.  These then become thicker and denser, taking up with
+avidity certain stains, which are used as aids to investigation, and
+finally form longer or shorter, variously bent, rodlets of uniform
+thickness.  In these organs which, on account of their special property of
+absorbing certain stains, were styled Chromosomes (By W. Waldeyer in
+1888.), there may usually be recognised a separation into thicker and
+thinner discs; the former are often termed Chromomeres.  (Discovered by W.
+Pfitzner in 1880.)  In the course of division of the nucleus, the single
+rows of chromomeres in the chromosomes are doubled and this produces a
+band-like flattening and leads to the longitudinal splitting by which each
+chromosome is divided into two exactly equal halves.  The nuclear membrane
+then disappears and fibrillar cell-plasma or cytoplasm invades the nuclear
+area.  In animal cells these fibrillae in the cytoplasm centre on definite
+bodies (Their existence and their multiplication by fission were
+demonstrated by E. van Beneden and Th. Boveri in 1887.), which it is
+customary to speak of as Centrosomes.  Radiating lines in the adjacent
+cell-plasma suggest that these bodies constitute centres of force.  The
+cells of the higher plants do not possess such individualised centres; they
+have probably disappeared in the course of phylogenetic development:  in
+spite of this, however, in the nuclear division-figures the fibrillae of
+the cell-plasma are seen to radiate from two opposite poles.  In both
+animal and plant cells a fibrillar bipolar spindle is formed, the fibrillae
+of which grasp the longitudinally divided chromosomes from two opposite
+sides and arrange them on the equatorial plane of the spindle as the so-
+called nuclear or equatorial plate.  Each half-chromosome is connected with
+one of the spindle poles only and is then drawn towards that pole.  (These
+important facts, suspected by W. Flemming in 1882, were demonstrated by E.
+Heuser, L. Guignard, E. van Beneden, M. Nussbaum, and C. Rabl.)
+
+The formation of the daughter-nuclei is then effected.  The changes which
+the daughter-chromosomes undergo in the process of producing the daughter-
+nuclei repeat in the reverse order the changes which they went through in
+the course of their progressive differentiation from the mother-nucleus. 
+The division of the cell-body is completed midway between the two daughter-
+nuclei.  In animal cells, which possess no chemically differentiated
+membrane, separation is effected by simple constriction, while in the case
+of plant cells provided with a definite wall, the process begins with the
+formation of a cytoplasmic separating layer.
+
+The phenomena observed in the course of the division of the nucleus show
+beyond doubt that an exact halving of its substance is of the greatest
+importance.  (First shown by W. Roux in 1883.)  Compared with the method of
+division of the nucleus, that of the cytoplasm appears to be very simple. 
+This led to the conception that the cell-nucleus must be the chief if not
+the sole carrier of hereditary characters in the organism.  It is for this
+reason that the detailed investigation of fertilisation phenomena
+immediately followed researches into the nucleus.  The fundamental
+discovery of the union of two nuclei in the sexual act was then made (By O.
+Hertwig in 1875.) and this afforded a new support for the correct
+conception of the nuclear functions.  The minute study of the behaviour of
+the other constituents of sexual cells during fertilisation led to the
+result, that the nucleus alone is concerned with handing on hereditary
+characters (This was done by O. Hertwig and the author of this essay
+simultaneously in 1884.) from one generation to another.  Especially
+important, from the point of view of this conclusion, is the study of
+fertilisation in Angiosperms (Flowering plants); in these plants the male
+sexual cells lose their cell-body in the pollen-tube and the nucleus only--
+the sperm-nucleus--reaches the egg.  The cytoplasm of the male sexual cell
+is therefore not necessary to ensure a transference of hereditary
+characters from parents to offspring.  I lay stress on the case of the
+Angiosperms because researches recently repeated with the help of the
+latest methods failed to obtain different results.  As regards the
+descendants of angiospermous plants, the same laws of heredity hold good as
+for other sexually differentiated organisms; we may, therefore, extend to
+the latter what the Angiosperms so clearly teach us.
+
+The next advance in the hitherto rapid progress in our knowledge of nuclear
+division was delayed, because it was not at once recognised that there are
+two absolutely different methods of nuclear division.  All such nuclear
+divisions were united under the head of indirect or mitotic divisions;
+these were also spoken of as karyo-kineses, and were distinguished from the
+direct or amitotic divisions which are characterised by a simple
+constriction of the nuclear body.  So long as the two kinds of indirect
+nuclear division were not clearly distinguished, their correct
+interpretation was impossible.  This was accomplished after long and
+laborious research, which has recently been carried out and with results
+which should, perhaps, be regarded as provisional.
+
+Soon after the new study of the nucleus began, investigators were struck by
+the fact that the course of nuclear division in the mother-cells, or more
+correctly in the grandmother-cells, of spores, pollen-grains, and embryo-
+sacs of the more highly organised plants and in the spermatozoids and eggs
+of the higher animals, exhibits similar phenomena, distinct from those
+which occur in the somatic cells.
+
+In the nuclei of all those cells which we may group together as gonotokonts
+(At the suggestion of J.P. Lotsy in 1904.) (i.e. cells concerned in
+reproduction) there are fewer chromosomes than in the adjacent body-cells
+(somatic cells).  It was noticed also that there is a peculiarity
+characteristic of the gonotokonts, namely the occurrence of two nuclear
+divisions rapidly succeeding one another.  It was afterwards recognised
+that in the first stage of nuclear division in the gonotokonts the
+chromosomes unite in pairs:  it is these chromosome-pairs, and not the two
+longitudinal halves of single chromosomes, which form the nuclear plate in
+the equatorial plane of the nuclear spindle.  It has been proposed to call
+these pairs gemini.  (J.E.S. Moore and A.L. Embleton, "Proc. Roy. Soc."
+London, Vol. LXXVII. page 555, 1906; V. Gregoire, 1907.)  In the course of
+this division the spindle-fibrillae attach themselves to the gemini, i.e.
+to entire chromosomes and direct them to the points where the new daughter-
+nuclei are formed, that is to those positions towards which the
+longitudinal halves of the chromosomes travel in ordinary nuclear
+divisions.  It is clear that in this way the number of chromosomes which
+the daughter-nuclei contain, as the result of the first stage in division
+in the gonotokonts, will be reduced by one half, while in ordinary
+divisions the number of chromosomes always remains the same.  The first
+stage in the division of the nucleus in the gonotokonts has therefore been
+termed the reduction division.  (In 1887 W. Flemming termed this the
+heterotypic form of nuclear division.)  This stage in division determines
+the conditions for the second division which rapidly ensues.  Each of the
+paired chromosomes of the mother-nucleus has already, as in an ordinary
+nuclear division, completed the longitudinal fission, but in this case it
+is not succeeded by the immediate separation of the longitudinal halves and
+their allotment to different nuclei.  Each chromosome, therefore, takes its
+two longitudinal halves into the same daughter-nucleus.  Thus, in each
+daughter-nucleus the longitudinal halves of the chromosomes are present
+ready for the next stage in the division; they only require to be arranged
+in the nuclear plate and then distributed among the granddaughter-nuclei.
+This method of division, which takes place with chromosomes already split,
+and which have only to provide for the distribution of their longitudinal
+halves to the next nuclear generation, has been called homotypic nuclear
+division.  (The name was proposed by W. Flemming in 1887; the nature of
+this type of division was, however, not explained until later.)
+
+Reduction division and homotypic nuclear division are included together
+under the term allotypic nuclear division and are distinguished from the
+ordinary or typical nuclear division.  The name Meiosis (By J. Bretland
+Farmer and J.E.S. Moore in 1905.) has also been proposed for these two
+allotypic nuclear divisions.  The typical divisions are often spoken of as
+somatic.
+
+Observers who were actively engaged in this branch of recent histological
+research soon noticed that the chromosomes of a given organism are
+differentiated in definite numbers from the nuclear network in the course
+of division.  This is especially striking in the gonotokonts, but it
+applies also to the somatic tissues.  In the latter, one usually finds
+twice as many chromosomes as in the gonotokonts.  Thus the conclusion was
+gradually reached that the doubling of chromosomes, which necessarily
+accompanies fertilisation, is maintained in the product of fertilisation,
+to be again reduced to one half in the gonotokonts at the stage of
+reduction-division.  This enabled us to form a conception as to the essence
+of true alternation of generations, in which generations containing single
+and double chromosomes alternate with one another.
+
+The single-chromosome generation, which I will call the HAPLOID, must have
+been the primitive generation in all organisms; it might also persist as
+the only generation.  Every sexual differentiation in organisms, which
+occurred in the course of phylogenetic development, was followed by
+fertilisation and therefore by the creation of a diploid or double-
+chromosome product.  So long as the germination of the product of
+fertilisation, the zygote, began with a reducing process, a special DIPLOID
+generation was not represented.  This, however, appeared later as a product
+of the further evolution of the zygote, and the reduction division was
+correspondingly postponed.  In animals, as in plants, the diploid
+generation attained the higher development and gradually assumed the
+dominant position.  The haploid generation suffered a proportional
+reduction, until it finally ceased to have an independent existence and
+became restricted to the role of producing the sexual products within the
+body of the diploid generation.  Those who do not possess the necessary
+special knowledge are unable to realise what remains of the first haploid
+generation in a phanerogamic plant or in a vertebrate animal.  In
+Angiosperms this is actually represented only by the short developmental
+stages which extend from the pollen mother-cells to the sperm-nucleus of
+the pollen-tube, and from the embryo-sac mother-cell to the egg and the
+endosperm tissue.  The embryo-sac remains enclosed in the diploid ovule,
+and within this from the fertilised egg is formed the embryo which
+introduces the new diploid generation.  On the full development of the
+diploid embryo of the next generation, the diploid ovule of the preceding
+diploid generation is separated from the latter as a ripe seed.  The
+uninitiated sees in the more highly organised plants only a succession of
+diploid generations.  Similarly all the higher animals appear to us as
+independent organisms with diploid nuclei only.  The haploid generation is
+confined in them to the cells produced as the result of the reduction
+division of the gonotokonts; the development of these is completed with the
+homotypic stage of division which succeeds the reduction division and
+produces the sexual products.
+
+The constancy of the numbers in which the chromosomes separate themselves
+from the nuclear network during division gave rise to the conception that,
+in a certain degree, chromosomes possess individuality.  Indeed the most
+careful investigations (Particularly those of V. Gregoire and his pupils.)
+have shown that the segments of the nuclear network, which separate from
+one another and condense so as to produce chromosomes for a new division,
+correspond to the segments produced from the chromosomes of the preceding
+division.  The behaviour of such nuclei as possess chromosomes of unequal
+size affords confirmatory evidence of the permanence of individual
+chromosomes in corresponding sections of an apparently uniform nuclear
+network.  Moreover at each stage in division chromosomes with the same
+differences in size reappear.  Other cases are known in which thicker
+portions occur in the substance of the resting nucleus, and these agree in
+number with the chromosomes.  In this network, therefore, the individual
+chromosomes must have retained their original position.  But the
+chromosomes cannot be regarded as the ultimate hereditary units in the
+nuclei, as their number is too small.  Moreover, related species not
+infrequently show a difference in the number of their chromosomes, whereas
+the number of hereditary units must approximately agree.  We thus picture
+to ourselves the carriers of hereditary characters as enclosed in the
+chromosomes; the transmitted fixed number of chromosomes is for us only the
+visible expression of the conception that the number of hereditary units
+which the chromosomes carry must be also constant.  The ultimate hereditary
+units may, like the chromosomes themselves, retain a definite position in
+the resting nucleus.  Further, it may be assumed that during the separation
+of the chromosomes from one another and during their assumption of the rod-
+like form, the hereditary units become aggregated in the chromomeres and
+that these are characterised by a constant order of succession.  The
+hereditary units then grow, divide into two and are uniformly distributed
+by the fission of the chromosomes between their longitudinal halves.
+
+As the contraction and rod-like separation of the chromosomes serve to
+isnure the transmission of all hereditary units in the products of division
+of a nucleus, so, on the other hand, the reticular distension of each
+chromosome in the so-called resting nucleus may effect a separation of the
+carriers of hereditary units from each other and facilitate the specific
+activity of each of them.
+
+In the stages preliminary to their division, the chromosomes become denser
+and take up a substance which increases their staining capacity; this is
+called chromatin.  This substance collects in the chromomeres and may form
+the nutritive material for the carriers of hereditary units which we now
+believe to be enclosed in them.  The chromatin cannot itself be the
+hereditary substance, as it afterwards leaves the chromosomes, and the
+amount of it is subject to considerable variation in the nucleus, according
+to its stage of development.  Conjointly with the materials which take part
+in the formation of the nuclear spindle and other processes in the cell,
+the chromatin accumulates in the resting nucleus to form the nucleoli.
+
+Naturally connected with the conclusion that the nuclei are the carriers of
+hereditary characters in the organism, is the question whether enucleate
+organisms can also exist.  Phylogenetic considerations give an affirmative
+answer to this question.  The differentiation into nucleus and cytoplasm
+represents a division of labour in the protoplast.  A study of organisms
+which belong to the lowest class of the organic world teaches us how this
+was accomplished.  Instead of well-defined nuclei, scattered granules have
+been described in the protoplasm of several of these organisms (Bacteria,
+Cyanophyceae, Protozoa.), characterised by the same reactions as nuclear
+material, provided also with a nuclear network, but without a limiting
+membrane.  (This is the result of the work of R. Hertwig and of the most
+recently published investigations.)  Thus the carriers of hereditary
+characters may originally have been distributed in the common protoplasm,
+afterwards coming together and eventually assuming a definite form as
+special organs of the cell.  It may be also assumed that in the protoplasm
+and in the primitive types of nucleus, the carriers of the same hereditary
+unit were represented in considerable quantity; they became gradually
+differentiated to an extent commensurate with newly acquired characters. 
+It was also necessary that, in proportion as this happened, the mechanism
+of nuclear division must be refined.  At first processes resembling a
+simple constriction would suffice to provide for the distribution of all
+hereditary units to each of the products of division, but eventually in
+both organic kingdoms nuclear division, which alone insured the qualitative
+identity of the products of division, became a more marked feature in the
+course of cell-multiplication.
+
+Where direct nuclear division occurs by constriction in the higher
+organisms, it does not result in the halving of hereditary units.  So far
+as my observations go, direct nuclear division occurs in the more highly
+organised plants only in cells which have lost their specific functions. 
+Such cells are no longer capable of specific reproduction.  An interesting
+case in this connection is afforded by the internodal cells of the
+Characeae, which possess only vegetative functions.  These cells grow
+vigorously and their cytoplasm increases, their growth being accompanied by
+a correspondingly direct multiplication of the nuclei.  They serve chiefly
+to nourish the plant, but, unlike the other cells, they are incapable of
+producing any offspring.  This is a very instructive case, because it
+clearly shows that the nuclei are not only carriers of hereditary
+characters, but that they also play a definite part in the metabolism of
+the protoplasts.
+
+Attention was drawn to the fact that during the reducing division of nuclei
+which contain chromosomes of unequal size, gemini are constantly produced
+by the pairing of chromosomes of the same size.  This led to the conclusion
+that the pairing chromosomes are homologous, and that one comes from the
+father, the other from the mother.  (First stated by T.H. Montgomery in
+1901 and by W.S. Sutton in 1902.)  This evidently applies also to the
+pairing of chromosomes in those reduction-divisions in which differences in
+size do not enable us to distinguish the individual chromosomes.  In this
+case also each pair would be formed by two homologous chromosomes, the one
+of paternal, the other of maternal origin.  When the separation of these
+chromosomes and their distribution to both daughter-nuclei occur a
+chromosome of each kind is provided for each of these nuclei.  It would
+seem that the components of each pair might pass to either pole of the
+nuclear spindle, so that the paternal and maternal chromosomes would be
+distributed in varying proportion between the daughter-nuclei; and it is
+not impossible that one daughter-nucleus might occasionally contain
+paternal chromosomes only and its sister-nucleus exclusively maternal
+chromosomes.
+
+The fact that in nuclei containing chromosomes of various sizes, the
+chromosomes which pair together in reduction-division are always of equal
+size, constitutes a further and more important proof of their qualitative
+difference.  This is supported also by ingenious experiments which led to
+an unequal distribution of chromosomes in the products of division of a
+sea-urchin's egg, with the result that a difference was induced in their
+further development.  (Demonstrated by Th. Boveri in 1902.)
+
+The recently discovered fact that in diploid nuclei the chromosomes are
+arranged in pairs affords additional evidence in favour of the unequal
+value of the chromosomes.  This is still more striking in the case of
+chromosomes of different sizes.  It has been shown that in the first
+division-figure in the nucleus of the fertilised egg the chromosomes of
+corresponding size form pairs.  They appear with this arrangement in all
+subsequent nuclear divisions in the diploid generation.  The longitudinal
+fissions of the chromosomes provide for the unaltered preservation of this
+condition.  In the reduction nucleus of the gonotokonts the homologous
+chromosomes being near together need not seek out one another; they are
+ready to form gemini.  The next stage is their separation to the haploid
+daughter-nuclei, which have resulted from the reduction process.
+
+Peculiar phenomena in the reduction nucleus accompany the formation of
+gemini in both organic kingdoms.  (This has been shown more particularly by
+the work of L. Guignard, M. Mottier, J.B. Farmer, C.B. Wilson, V. Hacker
+and more recently by V. Gregoire and his pupil C.A. Allen, by the
+researches conducted in the Bonn Botanical Institute, and by A. and K.E.
+Schreiner.)  Probably for the purpose of entering into most intimate
+relation, the pairs are stretched to long threads in which the chromomeres
+come to lie opposite one another.  (C.A. Allen, A. and K.E. Schreiner, and
+Strasburger.)  It seems probable that these are homologous chromomeres, and
+that the pairs afterwards unite for a short time, so that an exchange of
+hereditary units is rendered possible.  (H. de Vries and Strasburger.) 
+This cannot be actually seen, but certain facts of heredity point to the
+conclusion that this occurs.  It follows from these phenomena that any
+exchange which may be effected must be one of homologous carriers of
+hereditary units only.  These units continue to form exchangeable segments
+after they have undergone unequal changes; they then constitute
+allelotropic pairs.  We may thus calculate what sum of possible
+combinations the exchange of homologous hereditary units between the
+pairing chromosomes provides for before the reduction division and the
+subsequent distribution of paternal and maternal chromosomes in the haploid
+daughter-nuclei.  These nuclei then transmit their characters to the sexual
+cells, the conjugation of which in fertilization again produces the most
+varied combinations.  (A.  Weismann gave the impulse to these ideas in his
+theory on "Amphimixis".)  In this way all the cooperations which the
+carriers of hereditary characters are capable of in a species are produced;
+this must give it an appreciable advantage in the struggle for life.
+
+The admirers of Charles Darwin must deeply regret that he did not live to
+see the results achieved by the new Cytology.  What service would they have
+been to him in the presentation of his hypothesis of Pangenesis; what an
+outlook into the future would they have given to his active mind!
+
+The Darwinian hypothesis of Pangenesis rests on the conception that all
+inheritable properties are represented in the cells by small invisible
+particles or gemmules and that these gemmules increase by division. 
+Cytology began to develop on new lines some years after the publication in
+1868 of Charles Darwin's "Provisional hypothesis of Pangenesis" ("Animals
+and Plants under Domestication", London, 1868, Chapter XXVII.), and when he
+died in 1882 it was still in its infancy.  Darwin would have soon suggested
+the substitution of the nuclei for his gemmules.  At least the great
+majority of present-day investigators in the domain of cytology have been
+led to the conclusion that the nucleus is the carrier of hereditary
+characters, and they also believe that hereditary characters are
+represented in the nucleus as distinct units.  Such would be Darwin's
+gemmules, which in conformity with the name of his hypothesis may be called
+pangens (So called by H. de Vries in 1889.):  these pangens multiply by
+division.  All recently adopted views may be thus linked on to this part of
+Darwin's hypothesis.  It is otherwise with Darwin's conception to which
+Pangenesis owes its name, namely the view that all cells continually give
+off gemmules, which migrate to other places in the organism, where they
+unite to form reproductive cells.  When Darwin foresaw this possibility,
+the continuity of the germinal substance was still unknown (Demonstrated by
+Nussbaum in 1880, by Sachs in 1882, and by Weismann in 1885.), a fact which
+excludes a transference of gemmules.
+
+But even Charles Darwin's genius was confined within finite boundaries by
+the state of science in his day.
+
+It is not my province to deal with other theories of development which
+followed from Darwin's Pangenesis, or to discuss their histological
+probabilities.  We can, however, affirm that Charles Darwin's idea that
+invisible gemmules are the carriers of hereditary characters and that they
+multiply by division has been removed from the position of a provisional
+hypothesis to that of a well-founded theory.  It is supported by histology,
+and the results of experimental work in heredity, which are now assuming
+extraordinary prominence, are in close agreement with it.
+
+
+VII.  "THE DESCENT OF MAN"
+
+By G. SCHWALBE.
+Professor of Anatomy in the University of Strassburg.
+
+The problem of the origin of the human race, of the descent of man, is
+ranked by Huxley in his epoch-making book "Man's Place in Nature", as the
+deepest with which biology has to concern itself, "the question of
+questions,"--the problem which underlies all others.  In the same brilliant
+and lucid exposition, which appeared in 1863, soon after the publication of
+Darwin's "Origin of Species", Huxley stated his own views in regard to this
+great problem.  He tells us how the idea of a natural descent of man
+gradually grew up in his mind, it was especially the assertions of Owen in
+regard to the total difference between the human and the simian brain that
+called forth strong dissent from the great anatomist Huxley, and he easily
+succeeded in showing that Owen's supposed differences had no real
+existence; he even established, on the basis of his own anatomical
+investigations, the proposition that the anatomical differences between the
+Marmoset and the Chimpanzee are much greater than those between the
+Chimpanzee and Man.
+
+But why do we thus introduce the study of Darwin's "Descent of Man", which
+is to occupy us here, by insisting on the fact that Huxley had taken the
+field in defence of the descent of man in 1863, while Darwin's book on the
+subject did not appear till 1871?  It is in order that we may clearly
+understand how it happened that from this time onwards Darwin and Huxley
+followed the same great aim in the most intimate association.
+
+Huxley and Darwin working at the same Problema maximum!  Huxley fiery,
+impetuous, eager for battle, contemptuous of the resistance of a dull
+world, or energetically triumphing over it.  Darwin calm, weighing every
+problem slowly, letting it mature thoroughly,--not a fighter, yet having
+the greater and more lasting influence by virtue of his immense mass of
+critically sifted proofs.  Darwin's friend, Huxley, was the first to do him
+justice, to understand his nature, and to find in it the reason why the
+detailed and carefully considered book on the descent of man made its
+appearance so late.  Huxley, always generous, never thought of claiming
+priority for himself.  In enthusiastic language he tells how Darwin's
+immortal work, "The Origin of Species", first shed light for him on the
+problem of the descent of man; the recognition of a vera causa in the
+transformation of species illuminated his thoughts as with a flash.  He was
+now content to leave what perplexed him, what he could not yet solve, as he
+says himself, "in the mighty hands of Darwin."  Happy in the bustle of
+strife against old and deep-rooted prejudices, against intolerance and
+superstition, he wielded his sharp weapons on Darwin's behalf; wearing
+Darwin's armour he joyously overthrew adversary after adversary.  Darwin
+spoke of Huxley as his "general agent."  ("Life and Letters of Thomas Henry
+Huxley", Vol. I. page 171, London, 1900.)  Huxley says of himself "I am
+Darwin's bulldog."  (Ibid. page 363.)
+
+Thus Huxley openly acknowledged that it was Darwin's "Origin of Species"
+that first set the problem of the descent of man in its true light, that
+made the question of the origin of the human race a pressing one.  That
+this was the logical consequence of his book Darwin himself had long felt.
+He had been reproached with intentionally shirking the application of his
+theory to Man.  Let us hear what he says on this point in his
+autobiography:  "As soon as I had become, in the year 1837 or 1838,
+convinced that species were mutable productions, I could not avoid the
+belief that man must come under the same law.  Accordingly I collected
+notes on the subject for my own satisfaction, and not for a long time with
+any intention of publishing.  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 (No italics in original.), to add that by the work 'light would be
+thrown on the origin of man and his history.'  It would have been useless
+and injurious to the success of the book to have paraded, without giving
+any evidence, my conviction with respect to his origin."  ("Life and
+Letters of Charles Darwin", Vol. 1. page 93.)
+
+In a letter written in January, 1860, to the Rev. L. Blomefield, Darwin
+expresses himself in similar terms.  "With respect to man, I am very far
+from wishing to obtrude my belief; but I thought it dishonest to quite
+conceal my opinion."  (Ibid. Vol. II. page 263.)
+
+The brief allusion in the "Origin of Species" is so far from prominent and
+so incidental that it was excusable to assume that Darwin had not touched
+upon the descent of man in this work.  It was solely the desire to have his
+mass of evidence sufficiently complete, solely Darwin's great
+characteristic of never publishing till he had carefully weighed all
+aspects of his subject for years, solely, in short, his most fastidious
+scientific conscience that restrained him from challenging the world in
+1859 with a book in which the theory of the descent of man was fully set
+forth.  Three years, frequently interrupted by ill-health, were needed for
+the actual writing of the book ("Life and Letters", Vol. I. page 94.):  the
+first edition, which appeared in 1871, was followed in 1874 by a much
+improved second edition, the preparation of which he very reluctantly
+undertook.  (Ibid. Vol. III. page 175.)
+
+This, briefly, is the history of the work, which, with the "Origin of
+Species", marks an epoch in the history of biological sciences--the work
+with which the cautious, peace-loving investigator ventured forth from his
+contemplative life into the arena of strife and unrest, and laid himself
+open to all the annoyances that deep-rooted belief and prejudice, and the
+prevailing tendency of scientific thought at the time could devise.
+
+Darwin did not take this step lightly.  Of great interest in this
+connection is a letter written to Wallace on Dec. 22, 1857 (Ibid. Vol. II.
+page 109.), in which he says "You ask whether I shall discuss 'man.'  I
+think I shall avoid the whole subject, as so surrounded with prejudices;
+though I fully admit that it is the highest and most interesting problem
+for the naturalist."  But his conscientiousness compelled him to state
+briefly his opinion on the subject in the "Origin of Species" in 1859. 
+Nevertheless he did not escape reproaches for having been so reticent. 
+This is unmistakably apparent from a letter to Fritz Muller dated February
+22 (1869?), in which he says:  "I am thinking of writing a little essay on
+the Origin of Mankind, as I have been taunted with concealing my opinions." 
+(Ibid. Vol. III. page 112.)
+
+It might be thought that Darwin behaved thus hesitatingly, and was so slow
+in deciding on the full publication of his collected material in regard to
+the descent of man, because he had religious difficulties to overcome.
+
+But this was not the case, as we can see from his admirable confession of
+faith, the publication of which we owe to his son Francis.  (Ibid. Vol. I.
+pages 304-317.)  Whoever wishes really to understand the lofty character of
+this great man should read these immortal lines in which he unfolds to us
+in simple and straightforward words the development of his conception of
+the universe.  He describes how, though he was still quite orthodox during
+his voyage round the world on board the "Beagle", he came gradually to see,
+shortly afterwards (1836-1839) that the Old Testament was no more to be
+trusted than the Sacred Books of the Hindoos; the miracles by which
+Christianity is supported, the discrepancies between the accounts in the
+different Gospels, gradually led him to disbelieve in Christianity as a
+divine revelation.  "Thus," he writes ("Life and Letters", Vol. 1. page
+309.), "disbelief crept over me at a very slow rate, but was at last
+complete.  The rate was so slow that I felt no distress."  But Darwin was
+too modest to presume to go beyond the limits laid down by science.  He
+wanted nothing more than to be able to go, freely and unhampered by belief
+in authority or in the Bible, as far as human knowledge could lead him.  We
+learn this from the concluding words of his chapter on religion:  "The
+mystery of the beginning of all things is insoluble by us; and I for one
+must be content to remain an Agnostic."  (Loc. cit. page 313.)
+
+Darwin was always very unwilling to give publicity to his views in regard
+to religion.  In a letter to Asa Gray on May 22, 1860 (Ibid. Vol. II. page
+310.), he declares that it is always painful to him to have to enter into
+discussion of religious problems.  He had, he said, no intention of writing
+atheistically.
+
+Finally, let us cite one characteristic sentence from a letter from Darwin
+to C. Ridley (Ibid. Vol. III. page. 236.  ("C. Ridley," Mr Francis Darwin
+points out to me, should be H.N. Ridley.  A.C.S.)) (Nov. 28, 1878.)  A
+clergyman, Dr Pusey, had asserted that Darwin had written the "Origin of
+Species" with some relation to theology.  Darwin writes emphatically, "Many
+years ago, when I was collecting facts for the 'Origin', my belief in what
+is called a personal God was as firm as that of Dr Pusey himself, and as to
+the eternity of matter I never troubled myself about such insoluble
+questions."  The expression "many years ago" refers to the time of his
+voyage round the world, as has already been pointed out.  Darwin means by
+this utterance that the views which had gradually developed in his mind in
+regard to the origin of species were quite compatible with the faith of the
+Church.
+
+If we consider all these utterances of Darwin in regard to religion and to
+his outlook on life (Weltanschauung), we shall see at least so much, that
+religious reflection could in no way have influenced him in regard to the
+writing and publishing of his book on "The Descent of Man".  Darwin had
+early won for himself freedom of thought, and to this freedom he remained
+true to the end of his life, uninfluenced by the customs and opinions of
+the world around him.
+
+Darwin was thus inwardly fortified and armed against the host of calumnies,
+accusations, and attacks called forth by the publication of the "Origin of
+Species", and to an even greater extent by the appearance of the "Descent
+of Man".  But in his defence he could rely on the aid of a band of
+distinguished auxiliaries of the rarest ability.  His faithful confederate,
+Huxley, was joined by the botanist Hooker, and, after longer resistance, by
+the famous geologist Lyell, whose "conversion" afforded Darwin peculiar
+satisfaction.  All three took the field with enthusiasm in defence of the
+natural descent of man.  From Wallace, on the other hand, though he shared
+with him the idea of natural selection, Darwin got no support in this
+matter.  Wallace expressed himself in a strange manner.  He admitted
+everything in regard to the morphological descent of man, but maintained,
+in a mystic way, that something else, something of a spiritual nature must
+have been added to what man inherited from his animal ancestors.  Darwin,
+whose esteem for Wallace was extraordinarily high, could not understand how
+he could give utterance to such a mystical view in regard to man; the idea
+seemed to him so "incredibly strange" that he thought some one else must
+have added these sentences to Wallace's paper.
+
+Even now there are thinkers who, like Wallace, shrink from applying to man
+the ultimate consequences of the theory of descent.  The idea that man is
+derived from ape-like forms is to them unpleasant and humiliating.
+
+So far I have been depicting the development of Darwin's work on the
+descent of man.  In what follows I shall endeavour to give a condensed
+survey of the contents of the book.
+
+It must at once be said that the contents of Darwin's work fall into two
+parts, dealing with entirely different subjects.  "The Descent of Man"
+includes a very detailed investigation in regard to secondary sexual
+characters in the animal series, and on this investigation Darwin founded a
+new theory, that of sexual selection.  With astonishing patience he
+gathered together an immense mass of material, and showed, in regard to
+Arthropods and Vertebrates, the wide distribution of secondary characters,
+which develop almost exclusively in the male, and which enable him, on the
+one hand, to get the better of his rivals in the struggle for the female by
+the greater perfection of his weapons, and on the other hand, to offer
+greater allurements to the female through the higher development of
+decorative characters, of song, or of scent-producing glands.  The best
+equipped males will thus crowd out the less well-equipped in the matter of
+reproduction, and thus the relevant characters will be increased and
+perfected through sexual selection.  It is, of course, a necessary
+assumption that these secondary sexual characters may be transmitted to the
+female, although perhaps in rudimentary form.
+
+As we have said, this theory of sexual selection takes up a great deal of
+space in Darwin's book, and it need only be considered here in so far as
+Darwin applied it to the descent of man.  To this latter problem the whole
+of Part I is devoted, while Part III contains a discussion of sexual
+selection in relation to man, and a general summary.  Part II treats of
+sexual selection in general, and may be disregarded in our present study.
+Moreover, many interesting details must necessarily be passed over in what
+follows, for want of space.
+
+The first part of the "Descent of Man" begins with an enumeration of the
+proofs of the animal descent of man taken from the structure of the human
+body.  Darwin chiefly emphasises the fact that the human body consists of
+the same organs and of the same tissues as those of the other mammals; he
+shows also that man is subject to the same diseases and tormented by the
+same parasites as the apes.  He further dwells on the general agreement
+exhibited by young, embryonic forms, and he illustrates this by two figures
+placed one above the other, one representing a human embryo, after Eaker,
+the other a dog embryo, after Bischoff.  ("Descent of Man" (Popular
+Edition, 1901), fig. 1, page 14.)
+
+Darwin finds further proofs of the animal origin of man in the reduced
+structures, in themselves extremely variable, which are either absolutely
+useless to their possessors, or of so little use that they could never have
+developed under existing conditions.  Of such vestiges he enumerates:  the
+defective development of the panniculus carnosus (muscle of the skin) so
+widely distributed among mammals, the ear-muscles, the occasional
+persistence of the animal ear-point in man, the rudimentary nictitating
+membrane (plica semilunaris) in the human eye, the slight development of
+the organ of smell, the general hairiness of the human body, the frequently
+defective development or entire absence of the third molar (the wisdom
+tooth), the vermiform appendix, the occasional reappearance of a bony canal
+(foramen supracondyloideum) at the lower end of the humerus, the
+rudimentary tail of man (the so-called taillessness), and so on.  Of these
+rudimentary structures the occasional occurrence of the animal ear-point in
+man is most fully discussed.  Darwin's attention was called to this
+interesting structure by the sculptor Woolner.  He figures such a case
+observed in man, and also the head of an alleged orang-foetus, the
+photograph of which he received from Nitsche.
+
+Darwin's interpretation of Woolner's case as having arisen through a
+folding over of the free edge of a pointed ear has been fully borne out by
+my investigations on the external ear. (G. Schwalbe, "Das Darwin'sche
+Spitzohr beim menschlichen Embryo", "Anatom. Anzeiger", 1889, pages 176-
+189, and other papers.)  In particular, it was established by these
+investigations that the human foetus, about the middle of its embryonic
+life, possesses a pointed ear somewhat similar to that of the monkey genus
+Macacus.  One of Darwin's statements in regard to the head of the orang-
+foetus must be corrected.  A LARGE ear with a point is shown in the
+photograph ("Descent of Man", fig.3, page 24.), but it can easily be
+demonstrated--and Deniker has already pointed this out--that the figure is
+not that of an orang-foetus at all, for that form has much smaller ears
+with no point; nor can it be a gibbon-foetus, as Deniker supposes, for the
+gibbon ear is also without a point.  I myself regard it as that of a
+Macacus-embryo.  But this mistake, which is due to Nitsche, in no way
+affects the fact recognised by Darwin, that ear-forms showing the point
+characteristic of the animal ear occur in man with extraordinary frequency.
+
+Finally, there is a discussion of those rudimentary structures which occur
+only in ONE sex, such as the rudimentary mammary glands in the male, the
+vesicula prostatica, which corresponds to the uterus of the female, and
+others.  All these facts tell in favour of the common descent of man and
+all other vertebrates.  The conclusion of this section is characteristic: 
+"IT IS ONLY OUR NATURAL PREJUDICE, AND THAT ARROGANCE WHICH MADE OUR
+FOREFATHERS DECLARE THAT THEY WERE DESCENDED FROM DEMI-GODS, WHICH LEADS US
+TO DEMUR TO THIS CONCLUSION.  BUT THE TIME WILL BEFORE LONG COME, WHEN IT
+WILL BE THOUGHT WONDERFUL THAT NATURALISTS, WHO WERE WELL ACQUAINTED WITH
+THE COMPARATIVE STRUCTURE AND DEVELOPMENT OF MAN, AND OTHER MAMMALS, SHOULD
+HAVE BELIEVED THAT EACH WAS THE WORK OF A SEPARATE ACT OF CREATION." 
+(Ibid. page 36.)
+
+In the second chapter there is a more detailed discussion, again based upon
+an extraordinary wealth of facts, of the problem as to the manner in which,
+and the causes through which, man evolved from a lower form.  Precisely the
+same causes are here suggested for the origin of man, as for the origin of
+species in general.  Variability, which is a necessary assumption in regard
+to all transformations, occurs in man to a high degree.  Moreover, the
+rapid multiplication of the human race creates conditions which necessitate
+an energetic struggle for existence, and thus afford scope for the
+intervention of natural selection.  Of the exercise of ARTIFICIAL selection
+in the human race, there is nothing to be said, unless we cite such cases
+as the grenadiers of Frederick William I, or the population of ancient
+Sparta.  In the passages already referred to and in those which follow, the
+transmission of acquired characters, upon which Darwin does not dwell, is
+taken for granted.  In man, direct effects of changed conditions can be
+demonstrated (for instance in regard to bodily size), and there are also
+proofs of the influence exerted on his physical constitution by increased
+use or disuse.  Reference is here made to the fact, established by Forbes,
+that the Quechua-Indians of the high plateaus of Peru show a striking
+development of lungs and thorax, as a result of living constantly at high
+altitudes.
+
+Such special forms of variation as arrests of development (microcephalism)
+and reversion to lower forms are next discussed.  Darwin himself felt
+("Descent of Man", page 54.) that these subjects are so nearly related to
+the cases mentioned in the first chapter, that many of them might as well
+have been dealt with there.  It seems to me that it would have been better
+so, for the citation of additional instances of reversion at this place
+rather disturbs the logical sequence of his ideas as to the conditions
+which have brought about the evolution of man from lower forms.  The
+instances of reversion here discussed are microcephalism, which Darwin
+wrongly interpreted as atavistic, supernumerary mammae, supernumerary
+digits, bicornuate uterus, the development of abnormal muscles, and so on.
+Brief mention is also made of correlative variations observed in man.
+
+Darwin next discusses the question as to the manner in which man attained
+to the erect position from the state of a climbing quadruped.  Here again
+he puts the influence of Natural Selection in the first rank.  The
+immediate progenitors of man had to maintain a struggle for existence in
+which success was to the more intelligent, and to those with social
+instincts.  The hand of these climbing ancestors, which had little skill
+and served mainly for locomotion, could only undergo further development
+when some early member of the Primate series came to live more on the
+ground and less among trees.
+
+A bipedal existence thus became possible, and with it the liberation of the
+hand from locomotion, and the one-sided development of the human foot.  The
+upright position brought about correlated variations in the bodily
+structure; with the free use of the hand it became possible to manufacture
+weapons and to use them; and this again resulted in a degeneration of the
+powerful canine teeth and the jaws, which were then no longer necessary for
+defence.  Above all, however, the intelligence immediately increased, and
+with it skull and brain.  The nakedness of man, and the absence of a tail
+(rudimentariness of the tail vertebrae) are next discussed.  Darwin is
+inclined to attribute the nakedness of man, not to the action of natural
+selection on ancestors who originally inhabited a tropical land, but to
+sexual selection, which, for aesthetic reasons, brought about the loss of
+the hairy covering in man, or primarily in woman.  An interesting
+discussion of the loss of the tail, which, however, man shares with the
+anthropoid apes, some other monkeys and lemurs, forms the conclusion of the
+almost superabundant material which Darwin worked up in the second chapter. 
+His object was to show that some of the most distinctive human characters
+are in all probability directly or indirectly due to natural selection. 
+With characteristic modesty he adds ("Descent of Man", page 92.):  "Hence,
+if I have erred in giving to natural selection great power, which I am very
+far from admitting, or in having exaggerated its power, which is in itself
+probable, I have at least, as I hope, done good service in aiding to
+overthrow the dogma of separate creations."  At the end of the chapter he
+touches upon the objection as to man's helpless and defenceless condition. 
+Against this he urges his intelligence and social instincts.
+
+The two following chapters contain a detailed discussion of the objections
+drawn from the supposed great differences between the mental powers of men
+and animals.  Darwin at once admits that the differences are enormous, but
+not that any fundamental difference between the two can be found.  Very
+characteristic of him is the following passage:  "In what manner the mental
+powers were first developed in the lowest organisms, is as hopeless an
+enquiry as how life itself first originated.  These are problems for the
+distant future, if they are ever to be solved by man."  (Ibid. page 100.)
+
+After some brief observations on instinct and intelligence, Darwin brings
+forward evidence to show that the greater number of the emotional states,
+such as pleasure and pain, happiness and misery, love and hate are common
+to man and the higher animals.  He goes on to give various examples showing
+that wonder and curiosity, imitation, attention, memory and imagination
+(dreams of animals), can also be observed in the higher mammals, especially
+in apes.  In regard even to reason there are no sharply defined limits.  A
+certain faculty of deliberation is characteristic of some animals, and the
+more thoroughly we know an animal the more intelligence we are inclined to
+credit it with.  Examples are brought forward of the intelligent and
+deliberate actions of apes, dogs and elephants.  But although no sharply
+defined differences exist between man and animals, there is, nevertheless,
+a series of other mental powers which are characteristics usually regarded
+as absolutely peculiar to man.  Some of these characteristics are examined
+in detail, and it is shown that the arguments drawn from them are not
+conclusive.  Man alone is said to be capable of progressive improvement;
+but against this must be placed as something analogous in animals, the fact
+that they learn cunning and caution through long continued persecution. 
+Even the use of tools is not in itself peculiar to man (monkeys use sticks,
+stones and twigs), but man alone fashions and uses implements DESIGNED FOR
+A SPECIAL PURPOSE.  In this connection the remarks taken from Lubbock in
+regard to the origin and gradual development of the earliest flint
+implements will be read with interest; these are similar to the
+observations on modern eoliths, and their bearing on the development of the
+stone-industry.  It is interesting to learn from a letter to Hooker ("Life
+and Letters", Vol. II. page 161, June 22, 1859.), that Darwin himself at
+first doubted whether the stone implements discovered by Boucher de Perthes
+were really of the nature of tools.  With the relentless candour as to
+himself which characterised him, he writes four years later in a letter to
+Lyell in regard to this view of Boucher de Perthes' discoveries:  "I know
+something about his errors, and looked at his book many years ago, and am
+ashamed to think that I concluded the whole was rubbish!  Yet he has done
+for man something like what Agassiz did for glaciers."  (Ibid. Vol. III.
+page 15, March 17, 1863.)
+
+To return to Darwin's further comparisons between the higher mental powers
+of man and animals.  He takes much of the force from the argument that man
+alone is capable of abstraction and self-consciousness by his own
+observations on dogs.  One of the main differences between man and animals,
+speech, receives detailed treatment.  He points out that various animals
+(birds, monkeys, dogs) have a large number of different sounds for
+different emotions, that, further, man produces in common with animals a
+whole series of inarticulate cries combined with gestures, and that dogs
+learn to understand whole sentences of human speech.  In regard to human
+language, Darwin expresses a view contrary to that held by Max Muller
+("Descent of Man", page 132.):  "I cannot doubt that language owes its
+origin to the imitation and modification of various natural sounds, the
+voices of other animals, and man's own instinctive cries, aided by signs
+and gestures."  The development of actual language presupposes a higher
+degree of intelligence than is found in any kind of ape.  Darwin remarks on
+this point (Ibid. pages 136, 137.):  "The fact of the higher apes not using
+their vocal organs for speech no doubt depends on their intelligence not
+having been sufficiently advanced."
+
+The sense of beauty, too, has been alleged to be peculiar to man.  In
+refutation of this assertion Darwin points to the decorative colours of
+birds, which are used for display.  And to the last objection, that man
+alone has religion, that he alone has a belief in God, it is answered "that
+numerous races have existed, and still exist, who have no idea of one or
+more gods, and who have no words in their languages to express such an
+idea."  (Ibid. page 143.)
+
+The result of the investigations recorded in this chapter is to show that,
+great as the difference in mental powers between man and the higher animals
+may be, it is undoubtedly only a difference "of degree and not of kind." 
+("Descent of Man", page 193.)
+
+In the fourth chapter Darwin deals with the MORAL SENSE or CONSCIENCE,
+which is the most important of all differences between man and animals.  It
+is a result of social instincts, which lead to sympathy for other members
+of the same society, to non-egoistic actions for the good of others. 
+Darwin shows that social tendencies are found among many animals, and that
+among these love and kin-sympathy exist, and he gives examples of animals
+(especially dogs) which may exhibit characters that we should call moral in
+man (e.g. disinterested self-sacrifice for the sake of others).  The early
+ape-like progenitors of the human race were undoubtedly social.  With the
+increase of intelligence the moral sense develops farther; with the
+acquisition of speech public opinion arises, and finally, moral sense
+becomes habit.  The rest of Darwin's detailed discussions on moral
+philosophy may be passed over.
+
+The fifth chapter may be very briefly summarised.  In it Darwin shows that
+the intellectual and moral faculties are perfected through natural
+selection.  He inquires how it can come about that a tribe at a low level
+of evolution attains to a higher, although the best and bravest among them
+often pay for their fidelity and courage with their lives without leaving
+any descendants.  In this case it is the sentiment of glory, praise and
+blame, the admiration of others, which bring about the increase of the
+better members of the tribe.  Property, fixed dwellings, and the
+association of families into a community are also indispensable
+requirements for civilisation.  In the longer second section of the fifth
+chapter Darwin acts mainly as recorder.  On the basis of numerous
+investigations, especially those of Greg, Wallace, and Galton, he inquires
+how far the influence of natural selection can be demonstrated in regard to
+civilised nations.  In the final section, which deals with the proofs that
+all civilised nations were once barbarians, Darwin again uses the results
+gained by other investigators, such as Lubbock and Tylor.  There are two
+sets of facts which prove the proposition in question.  In the first place,
+we find traces of a former lower state in the customs and beliefs of all
+civilised nations, and in the second place, there are proofs to show that
+savage races are independently able to raise themselves a few steps in the
+scale of civilisation, and that they have thus raised themselves.
+
+In the sixth chapter of the work, Morphology comes into the foreground once
+more.  Darwin first goes back, however, to the argument based on the great
+difference between the mental powers of the highest animals and those of
+man.  That this is only quantitative, not qualitative, he has already
+shown.  Very instructive in this connection is the reference to the
+enormous difference in mental powers in another class.  No one would draw
+from the fact that the cochineal insect (Coccus) and the ant exhibit
+enormous differences in their mental powers, the conclusion that the ant
+should therefore be regarded as something quite distinct, and withdrawn
+from the class of insects altogether.
+
+Darwin next attempts to establish the SPECIFIC genealogical tree of man,
+and carefully weighs the differences and resemblances between the different
+families of the Primates.  The erect position of man is an adaptive
+character, just as are the various characters referable to aquatic life in
+the seals, which, notwithstanding these, are ranked as a mere family of the
+Carnivores.  The following utterance is very characteristic of Darwin
+("Descent of Man", page 231.):  "If man had not been his own classifier, he
+would never have thought of founding a separate order for his own
+reception."  In numerous characters not mentioned in systematic works, in
+the features of the face, in the form of the nose, in the structure of the
+external ear, man resembles the apes.  The arrangement of the hair in man
+has also much in common with the apes; as also the occurrence of hair on
+the forehead of the human embryo, the beard, the convergence of the hair of
+the upper and under arm towards the elbow, which occurs not only in the
+anthropoid apes, but also in some American monkeys.  Darwin here adopts
+Wallace's explanation of the origin of the ascending direction of the hair
+in the forearm of the orang,--that it has arisen through the habit of
+holding the hands over the head in rain.  But this explanation cannot be
+maintained when we consider that this disposition of the hair is widely
+distributed among the most different mammals, being found in the dog, in
+the sloth, and in many of the lower monkeys.
+
+After further careful analysis of the anatomical characters Darwin reaches
+the conclusion that the New World monkeys (Platyrrhine) may be excluded
+from the genealogical tree altogether, but that man is an offshoot from the
+Old World monkeys (Catarrhine) whose progenitors existed as far back as the
+Miocene period.  Among these Old World monkeys the forms to which man shows
+the greatest resemblance are the anthropoid apes, which, like him, possess
+neither tail nor ischial callosities.  The platyrrhine and catarrhine
+monkeys have their primitive ancestor among extinct forms of the Lemuridae. 
+Darwin also touches on the question of the original home of the human race
+and supposes that it may have been in Africa, because it is there that
+man's nearest relatives, the gorilla and the chimpanzee, are found.  But he
+regards speculation on this point as useless.  It is remarkable that, in
+this connection, Darwin regards the loss of the hair-covering in man as
+having some relation to a warm climate, while elsewhere he is inclined to
+make sexual selection responsible for it.  Darwin recognises the great gap
+between man and his nearest relatives, but similar gaps exist at other
+parts of the mammalian genealogical tree:  the allied forms have become
+extinct.  After the extermination of the lower races of mankind, on the one
+hand, and of the anthropoid apes on the other, which will undoubtedly take
+place, the gulf will be greater than ever, since the baboons will then
+bound it on the one side, and the white races on the other.  Little weight
+need be attached to the lack of fossil remains to fill up this gap, since
+the discovery of these depends upon chance.  The last part of the chapter
+is devoted to a discussion of the earlier stages in the genealogy of man. 
+Here Darwin accepts in the main the genealogical tree, which had meantime
+been published by Haeckel, who traces the pedigree back through Monotremes,
+Reptiles, Amphibians, and Fishes, to Amphioxus.
+
+Then follows an attempt to reconstruct, from the atavistic characters, a
+picture of our primitive ancestor who was undoubtedly an arboreal animal. 
+The occurrence of rudiments of parts in one sex which only come to full
+development in the other is next discussed.  This state of things Darwin
+regards as derived from an original hermaphroditism.  In regard to the
+mammary glands of the male he does not accept the theory that they are
+vestigial, but considers them rather as not fully developed.
+
+The last chapter of Part I deals with the question whether the different
+races of man are to be regarded as different species, or as sub-species of
+a race of monophyletic origin.  The striking differences between the races
+are first emphasised, and the question of the fertility or infertility of
+hybrids is discussed.  That fertility is the more usual is shown by the
+excessive fertility of the hybrid population of Brazil.  This, and the
+great variability of the distinguishing characters of the different races,
+as well as the fact that all grades of transition stages are found between
+these, while considerable general agreement exists, tell in favour of the
+unity of the races and lead to the conclusion that they all had a common
+primitive ancestor.
+
+Darwin therefore classifies all the different races as sub-species of ONE
+AND THE SAME SPECIES.  Then follows an interesting inquiry into the reasons
+for the extinction of human races.  He recognises as the ultimate reason
+the injurious effects of a change of the conditions of life, which may
+bring about an increase in infantile mortality, and a diminished fertility.
+It is precisely the reproductive system, among animals also, which is most
+susceptible to changes in the environment.
+
+The final section of this chapter deals with the formation of the races of
+mankind.  Darwin discusses the question how far the direct effect of
+different conditions of life, or the inherited effects of increased use or
+disuse may have brought about the characteristic differences between the
+different races.  Even in regard to the origin of the colour of the skin he
+rejects the transmitted effects of an original difference of climate as an
+explanation.  In so doing he is following his tendency to exclude
+Lamarckian explanations as far as possible.  But here he makes gratuitous
+difficulties from which, since natural selection fails, there is no escape
+except by bringing in the principle of sexual selection, to which, he
+regarded it as possible, skin-colouring, arrangement of hair, and form of
+features might be traced.  But with his characteristic conscientiousness he
+guards himself thus:  "I do not intend to assert that sexual selection will
+account for all the differences between the races."  ("Descent of Man",
+page 308.)
+
+I may be permitted a remark as to Darwin's attitude towards Lamarck. 
+While, at an earlier stage, when he was engaged in the preliminary labours
+for his immortal work, "The Origin of Species", Darwin expresses himself
+very forcibly against the views of Lamarck, speaking of Lamarckian
+"nonsense," ("Life and Letters", Vol. II. page 23.), and of Lamarck's
+"absurd, though clever work" (Loc. cit. page 39.) and expressly declaring,
+"I attribute very little to the direct action of climate, etc."  (Loc. cit.
+(1856), page 82.) yet in later life he became more and more convinced of
+the influence of external conditions.  In 1876, that is, two years after
+the appearance of the second edition of "The Descent of Man", he writes
+with his usual candid honesty:  "In my opinion the greatest error which I
+have committed, has been not allowing sufficient weight to the direct
+action of the environment, i.e. food, climate, etc. independently of
+natural selection."  (Ibid. Vol. III. page 159.)  It is certain from this
+change of opinion that, if he had been able to make up his mind to issue a
+third edition of "The Descent of Man", he would have ascribed a much
+greater influence to the effect of external conditions in explaining the
+different characters of the races of man than he did in the second edition.
+He would also undoubtedly have attributed less influence to sexual
+selection as a factor in the origin of the different bodily
+characteristics, if indeed he would not have excluded it altogether.
+
+In Part III of the "Descent" two additional chapters are devoted to the
+discussion of sexual selection in relation to man.  These may be very
+briefly referred to.  Darwin here seeks to show that sexual selection has
+been operative on man and his primitive progenitor.  Space fails me to
+follow out his interesting arguments.  I can only mention that he is
+inclined to trace back hairlessness, the development of the beard in man,
+and the characteristic colour of the different human races to sexual
+selection.  Since bareness of the skin could be no advantage, but rather a
+disadvantage, this character cannot have been brought about by natural
+selection.  Darwin also rejected a direct influence of climate as a cause
+of the origin of the skin-colour.  I have already expressed the opinion,
+based on the development of his views as shown in his letters, that in a
+third edition Darwin would probably have laid more stress on the influence
+of external environment.  He himself feels that there are gaps in his
+proofs here, and says in self-criticism:  "The views here advanced, on the
+part which sexual selection has played in the history of man, want
+scientific precision."  ("Descent of Man", page 924.)  I need here only
+point out that it is impossible to explain the graduated stages of skin-
+colour by sexual selection, since it would have produced races sharply
+defined by their colour and not united to other races by transition stages,
+and this, it is well known, is not the case.  Moreover, the fact
+established by me ("Die Hautfarbe des Menschen", "Mitteilungen der
+Anthropologischen Gesellschaft in Wien", Vol. XXXIV. pages 331-352.), that
+in all races the ventral side of the trunk is paler than the dorsal side,
+and the inner surface of the extremities paler than the outer side, cannot
+be explained by sexual selection in the Darwinian sense.
+
+With this I conclude my brief survey of the rich contents of Darwin's book.
+I may be permitted to conclude by quoting the magnificent final words of
+"The Descent of Man":  "We must, however, acknowledge, as it seems to me,
+that man, with all his noble qualities, with sympathy which feels for the
+most debased, with benevolence which extends not only to other men but to
+the humblest living creature, with his god-like intellect which has
+penetrated into the movements and constitution of the solar system--with
+all these exalted powers--Man still bears in his bodily frame the indelible
+stamp of his lowly origin."  (Ibid. page 947.)
+
+What has been the fate of Darwin's doctrines since his great achievement? 
+How have they been received and followed up by the scientific and lay
+world?  And what do the successors of the mighty hero and genius think now
+in regard to the origin of the human race?
+
+At the present time we are incomparably more favourably placed than Darwin
+was for answering this question of all questions.  We have at our command
+an incomparably greater wealth of material than he had at his disposal. 
+And we are more fortunate than he in this respect, that we now know
+transition-forms which help to fill up the gap, still great, between the
+lowest human races and the highest apes.  Let us consider for a little the
+more essential additions to our knowledge since the publication of "The
+Descent of Man".
+
+Since that time our knowledge of animal embryos has increased enormously.
+While Darwin was obliged to content himself with comparing a human embryo
+with that of a dog, there are now available the youngest embryos of monkeys
+of all possible groups (Orang, Gibbon, Semnopithecus, Macacus), thanks to
+Selenka's most successful tour in the East Indies in search of such
+material.  We can now compare corresponding stages of the lower monkeys and
+of the Anthropoid apes with human embryos, and convince ourselves of their
+great resemblance to one another, thus strengthening enormously the armour
+prepared by Darwin in defence of his view on man's nearest relatives.  It
+may be said that Selenka's material fils up the blanks in Darwin's array of
+proofs in the most satisfactory manner.
+
+The deepening of our knowledge of comparative anatomy also gives us much
+surer foundations than those on which Darwin was obliged to build.  Just of
+late there have been many workers in the domain of the anatomy of apes and
+lemurs, and their investigations extend to the most different organs.  Our
+knowledge of fossil apes and lemurs has also become much wider and more
+exact since Darwin's time:  the fossil lemurs have been especially worked
+up by Cope, Forsyth Major, Ameghino, and others.  Darwin knew very little
+about fossil monkeys.  He mentions two or three anthropoid apes as
+occurring in the Miocene of Europe ("Descent of Man", page 240.), but only
+names Dryopithecus, the largest form from the Miocene of France.  It was
+erroneously supposed that this form was related to Hylobates.  We now know
+not only a form that actually stands near to the gibbon (Pliopithecus), and
+remains of other anthropoids (Pliohylobates and the fossil chimpanzee,
+Palaeopithecus), but also several lower catarrhine monkeys, of which
+Mesopithecus, a form nearly related to the modern Sacred Monkeys (a species
+of Semnopithecus) and found in strata of the Miocene period in Greece, is
+the most important.  Quite recently, too, Ameghino's investigations have
+made us acquainted with fossil monkeys from South America (Anthropops,
+Homunculus), which, according to their discoverer, are to be regarded as in
+the line of human descent.
+
+What Darwin missed most of all--intermediate forms between apes and man--
+has been recently furnished.  (E. Dubois, as is well known, discovered in
+1893, near Trinil in Java, in the alluvial deposits of the river Bengawan,
+an important form represented by a skull-cap, some molars, and a femur. 
+His opinion--much disputed as it has been--that in this form, which he
+named Pithecanthropus, he has found a long-desired transition-form is
+shared by the present writer.  And although the geological age of these
+fossils, which, according to Dubois, belong to the uppermost Tertiary
+series, the Pliocene, has recently been fixed at a later date (the older
+Diluvium), the MORPHOLOGICAL VALUE of these interesting remains, that is,
+the intermediate position of Pithecanthropus, still holds good.  Volz says
+with justice ("Das geologische Alter der Pithecanthropus-Schichten bei
+Trinil, Ost-Java". "Neues Jahrb. f.Mineralogie".  Festband, 1907.), that
+even if Pithecanthropus is not THE missing link, it is undoubtedly _A_
+missing link.
+
+As on the one hand there has been found in Pithecanthropus a form which,
+though intermediate between apes and man, is nevertheless more closely
+allied to the apes, so on the other hand, much progress has been made since
+Darwin's day in the discovery and description of the older human remains. 
+Since the famous roof of a skull and the bones of the extremities belonging
+to it were found in 1856 in the Neandertal near Dusseldorf, the most varied
+judgments have been expressed in regard to the significance of the remains
+and of the skull in particular.  In Darwin's "Descent of Man" there is only
+a passing allusion to them ("Descent of Man", page 82.) in connection with
+the discussion of the skull-capacity, although the investigations of
+Schaaffhausen, King, and Huxley were then known.  I believe I have shown,
+in a series of papers, that the skull in question belongs to a form
+different from any of the races of man now living, and, with King and Cope,
+I regard it as at least a different species from living man, and have
+therefore designated it Homo primigenius.  The form unquestionably belongs
+to the older Diluvium, and in the later Diluvium human forms already
+appear, which agree in all essential points with existing human races.
+
+As far back as 1886 the value of the Neandertal skull was greatly enhanced
+by Fraipont's discovery of two skulls and skeletons from Spy in Belgium. 
+These are excellently described by their discoverer ("La race humaine de
+Neanderthal ou de Canstatt en Belgique".  "Arch. de Biologie", VII. 1887.),
+and are regarded as belonging to the same group of forms as the Neandertal
+remains.  In 1899 and the following years came the discovery by Gorjanovic-
+Kramberger of different skeletal parts of at least ten individuals in a
+cave near Krapina in Croatia.  (Gorjanovic-Kramberger "Der diluviale Mensch
+von Krapina in Kroatien", 1906.)  It is in particular the form of the lower
+jaw which is different from that of all recent races of man, and which
+clearly indicates the lowly position of Homo primigenius, while, on the
+other hand, the long-known skull from Gibraltar, which I ("Studien zur
+Vorgeschichte des Menschen", 1906, pages 154 ff.) have referred to Homo
+primigenius, and which has lately been examined in detail by Sollas ("On
+the cranial and facial characters of the Neandertal Race".  "Trans. R.
+Soc." London, vol. 199, 1908, page 281.), has made us acquainted with the
+surprising shape of the eye-orbit, of the nose, and of the whole upper part
+of the face.  Isolated lower jaws found at La Naulette in Belgium, and at
+Malarnaud in France, increase our material which is now as abundant as
+could be desired.  The most recent discovery of all is that of a skull dug
+up in August of this year (1908) by Klaatsch and Hauser in the lower grotto
+of the Le Moustier in Southern France, but this skull has not yet been
+fully described.  Thus Homo primigenius must also be regarded as occupying
+a position in the gap existing between the highest apes and the lowest
+human races, Pithecanthropus, standing in the lower part of it, and Homo
+primigenius in the higher, near man.  In order to prevent misunderstanding,
+I should like here to emphasise that in arranging this structural series--
+anthropoid apes, Pithecanthropus, Homo primigenius, Homo sapiens--I have no
+intention of establishing it as a direct genealogical series.  I shall have
+something to say in regard to the genetic relations of these forms, one to
+another, when discussing the different theories of descent current at the
+present day.  ((Since this essay was written Schoetensack has discovered
+near Heidelberg and briefly described an exceedingly interesting lower jaw
+from rocks between the Pliocene and Diluvial beds.  This exhibits
+interesting differences from the forms of lower jaw of Homo primigenius. 
+(Schoetensack "Der Unterkiefer des Homo heidelbergensis".  Leipzig, 1908.) 
+G.S.))
+
+In quite a different domain from that of morphological relationship, namely
+in the physiological study of the blood, results have recently been gained
+which are of the highest importance to the doctrine of descent.  Uhlenhuth,
+Nuttall, and others have established the fact that the blood-serum of a
+rabbit which has previously had human blood injected into it, forms a
+precipitate with human blood.  This biological reaction was tried with a
+great variety of mammalian species, and it was found that those far removed
+from man gave no precipitate under these conditions.  But as in other cases
+among mammals all nearly related forms yield an almost equally marked
+precipitate, so the serum of a rabbit treated with human blood and then
+added to the blood of an anthropoid ape gives ALMOST as marked a
+precipitate as in human blood; the reaction to the blood of the lower
+Eastern monkeys is weaker, that to the Western monkeys weaker still; indeed
+in this last case there is only a slight clouding after a considerable time
+and no actual precipitate.  The blood of the Lemuridae (Nuttall) gives no
+reaction or an extremely weak one, that of the other mammals none whatever.
+We have in this not only a proof of the literal blood-relationship between
+man and apes, but the degree of relationship with the different main groups
+of apes can be determined beyond possibility of mistake.
+
+Finally, it must be briefly mentioned that in regard to remains of human
+handicraft also, the material at our disposal has greatly increased of late
+years, that, as a result of this, the opinions of archaeologists have
+undergone many changes, and that, in particular, their views in regard to
+the age of the human race have been greatly influenced.  There is a
+tendency at the present time to refer the origin of man back to Tertiary
+times.  It is true that no remains of Tertiary man have been found, but
+flints have been discovered which, according to the opinion of most
+investigators, bear traces either of use, or of very primitive workmanship.
+Since Rutot's time, following Mortillet's example, investigators have
+called these "eoliths," and they have been traced back by Verworn to the
+Miocene of the Auvergne, and by Rutot even to the upper Oligocene. 
+Although these eoliths are even nowadays the subject of many different
+views, the preoccupation with them has kept the problem of the age of the
+human race continually before us.
+
+Geology, too, has made great progress since the days of Darwin and Lyell,
+and has endeavoured with satisfactory results to arrange the human remains
+of the Diluvial period in chronological order (Penck).  I do not intend to
+enter upon the question of the primitive home of the human race; since the
+space at my disposal will not allow of my touching even very briefly upon
+all the departments of science which are concerned in the problem of the
+descent of man.  How Darwin would have rejoiced over each of the
+discoveries here briefly outlined!  What use he would have made of the new
+and precious material, which would have prevented the discouragement from
+which he suffered when preparing the second edition of "The Descent of
+Man"!  But it was not granted to him to see this progress towards filling
+up the gaps in his edifice of which he was so painfully conscious.
+
+He did, however, have the satisfaction of seeing his ideas steadily gaining
+ground, notwithstanding much hostility and deep-rooted prejudice.  Even in
+the years between the appearance of "The Origin of Species" and of the
+first edition of the "Descent", the idea of a natural descent of man, which
+was only briefly indicated in the work of 1859, had been eagerly welcomed
+in some quarters.  It has been already pointed out how brilliantly Huxley
+contributed to the defence and diffusion of Darwin's doctrines, and how in
+"Man's Place in Nature" he has given us a classic work as a foundation for
+the doctrine of the descent of man.  As Huxley was Darwin's champion in
+England, so in Germany Carl Vogt, in particular, made himself master of the
+Darwinian ideas.  But above all it was Haeckel who, in energy, eagerness
+for battle, and knowledge may be placed side by side with Huxley, who took
+over the leadership in the controversy over the new conception of the
+universe.  As far back as 1866, in his "Generelle Morphologie", he had
+inquired minutely into the question of the descent of man, and not content
+with urging merely the general theory of descent from lower animal forms,
+he drew up for the first time genealogical trees showing the close
+relationships of the different animal groups; the last of these illustrated
+the relationships of Mammals, and among them of all groups of the Primates,
+including man.  It was Haeckel's genealogical trees that formed the basis
+of the special discussion of the relationships of man, in the sixth chapter
+of Darwin's "Descent of Man".
+
+In the last section of this essay I shall return to Haeckel's conception of
+the special descent of man, the main features of which he still upholds,
+and rightly so.  Haeckel has contributed more than any one else to the
+spread of the Darwinian doctrine.
+
+I can only allow myself a few words as to the spread of the theory of the
+natural descent of man in other countries.  The Parisian anthropological
+school, founded and guided by the genius of Broca, took up the idea of the
+descent of man, and made many notable contributions to it (Broca,
+Manouvrier, Mahoudeau, Deniker and others).  In England itself Darwin's
+work did not die.  Huxley took care of that, for he, with his lofty and
+unprejudiced mind, dominated and inspired English biology until his death
+on June 29, 1895.  He had the satisfaction shortly before his death of
+learning of Dubois' discovery, which he illustrated by a humorous sketch. 
+("Life and Letters of Thomas Henry Huxley", Vol. II. page 394.)  But there
+are still many followers in Darwin's footsteps in England.  Keane has
+worked at the special genealogical tree of the Primates; Keith has inquired
+which of the anthropoid apes has the greatest number of characters in
+common with man; Morris concerns himself with the evolution of man in
+general, especially with his acquisition of the erect position.  The recent
+discoveries of Pithecanthropus and Homo primigenius are being vigorously
+discussed; but the present writer is not in a position to form an opinion
+of the extent to which the idea of descent has penetrated throughout
+England generally.
+
+In Italy independent work in the domain of the descent of man is being
+produced, especially by Morselli; with him are associated, in the
+investigation of related problems, Sergi and Giuffrida-Ruggeri.  From the
+ranks of American investigators we may single out in particular the eminent
+geologist Cope, who championed with much decision the idea of the specific
+difference of Homo neandertalensis (primigenius) and maintained a more
+direct descent of man from the fossil Lemuridae.  In South America too, in
+Argentina, new life is stirring in this department of science.  Ameghino in
+Buenos Ayres has awakened the fossil primates of the Pampas formation to
+new life; he even believes that in Tetraprothomo, represented by a femur,
+he has discovered a direct ancestor of man.  Lehmann-Nitsche is working at
+the other side of the gulf between apes and men, and he describes a
+remarkable first cervical vertebra (atlas) from Monte Hermoso as belonging
+to a form which may bear the same relation to Homo sapiens in South America
+as Homo primigenius does in the Old World.  After a minute investigation he
+establishes a human species Homo neogaeus, while Ameghino ascribes this
+atlas vertebra to his Tetraprothomo.
+
+Thus throughout the whole scientific world there is arising a new life, an
+eager endeavour to get nearer to Huxley's problema maximum, to penetrate
+more deeply into the origin of the human race.  There are to-day very few
+experts in anatomy and zoology who deny the animal descent of man in
+general.  Religious considerations, old prejudices, the reluctance to
+accept man, who so far surpasses mentally all other creatures, as descended
+from "soulless" animals, prevent a few investigators from giving full
+adherence to the doctrine.  But there are very few of these who still
+postulate a special act of creation for man.  Although the majority of
+experts in anatomy and zoology accept unconditionally the descent of man
+from lower forms, there is much diversity of opinion among them in regard
+to the special line of descent.
+
+In trying to establish any special hypothesis of descent, whether by the
+graphic method of drawing up genealogical trees or otherwise, let us always
+bear in mind Darwin's words ("Descent of Man", page 229.) and use them as a
+critical guiding line:  "As we have no record of the lines of descent, the
+pedigree can be discovered only by observing the degrees of resemblance
+between the beings which are to be classed."  Darwin carries this further
+by stating "that resemblances in several unimportant structures, in useless
+and rudimentary organs, or not now functionally active, or in an
+embryological condition, are by far the most serviceable for
+classification."  (Loc. cit.)  It has also to be remembered that NUMEROUS
+separate points of agreement are of much greater importance than the amount
+of similarity or dissimilarity in a few points.
+
+The hypotheses as to descent current at the present day may be divided into
+two main groups.  The first group seeks for the roots of the human race not
+among any of the families of the apes--the anatomically nearest forms--nor
+among their very similar but less specialised ancestral forms, the fossil
+representatives of which we can know only in part, but, setting the monkeys
+on one side, it seeks for them lower down among the fossil Eocene Pseudo-
+lemuridae or Lemuridae (Cope), or even among the primitive pentadactylous
+Eocene forms, which may either have led directly to the evolution of man
+(Adloff), or have given rise to an ancestral form common to apes and men
+(Klaatsch (Klaatsch in his last publications speaks in the main only of an
+ancestral form common to men and anthropoid apes.), Giuffrida-Ruggeri). 
+The common ancestral form, from which man and apes are thus supposed to
+have arisen independently, may explain the numerous resemblances which
+actually exist between them.  That is to say, all the characters upon which
+the great structural resemblance between apes and man depends must have
+been present in their common ancestor.  Let us take an example of such a
+common character.  The bony external ear-passage is in general as highly
+developed in the lower Eastern monkeys and the anthropoid apes as in man. 
+This character must, therefore, have already been present in the common
+primitive form.  In that case it is not easy to understand why the Western
+monkeys have not also inherited the character, instead of possessing only a
+tympanic ring.  But it becomes more intelligible if we assume that forms
+with a primitive tympanic ring were the original type, and that from these
+were evolved, on the one hand, the existing New World monkeys with
+persistent tympanic ring, and on the other an ancestral form common to the
+lower Old World monkeys, the anthropoid apes and man.  For man shares with
+these the character in question, and it is also one of the "unimportant"
+characters required by Darwin.  Thus we have two divergent lines arising
+from the ancestral form, the Western monkeys (Platyrrhine) on the one hand,
+and an ancestral form common to the lower Eastern monkeys, the anthropoid
+apes, and man, on the other.  But considerations similar to those which
+showed it to be impossible that man should have developed from an ancestor
+common to him and the monkeys, yet outside of and parallel with these, may
+be urged also against the likelihood of a parallel evolution of the lower
+Eastern monkeys, the anthropoid apes, and man.  The anthropoid apes have in
+common with man many characters which are not present in the lower Old
+World monkeys.  These characters must therefore have been present in the
+ancestral form common to the three groups.  But here, again, it is
+difficult to understand why the lower Eastern monkeys should not also have
+inherited these characters.  As this is not the case, there remains no
+alternative but to assume divergent evolution from an indifferent form. 
+The lower Eastern monkeys are carrying on the evolution in one direction--I
+might almost say towards a blind alley--while anthropoids and men have
+struck out a progressive path, at first in common, which explains the many
+points of resemblance between them, without regarding man as derived
+directly from the anthropoids.  Their many striking points of agreement
+indicate a common descent, and cannot be explained as phenomena of
+convergence.
+
+I believe I have shown in the above sketch that a theory which derives man
+directly from lower forms without regarding apes as transition-types leads
+ad absurdum.  The close structural relationship between man and monkeys can
+only be understood if both are brought into the same line of evolution.  To
+trace man's line of descent directly back to the old Eocene mammals,
+alongside of, but with no relation to these very similar forms, is to
+abandon the method of exact comparison, which, as Darwin rightly
+recognised, alone justifies us in drawing up genealogical trees on the
+basis of resemblances and differences.  The farther down we go the more
+does the ground slip from beneath our feet.  Even the Lemuridae show very
+numerous divergent conditions, much more so the Eocene mammals (Creodonta,
+Condylarthra), the chief resemblance of which to man consists in the
+possession of pentadactylous hands and feet!  Thus the farther course of
+the line of descent disappears in the darkness of the ancestry of the
+mammals.  With just as much reason we might pass by the Vertebrates
+altogether, and go back to the lower Invertebrates, but in that case it
+would be much easier to say that man has arisen independently, and has
+evolved, without relation to any animals, from the lowest primitive form to
+his present isolated and dominant position.  But this would be to deny all
+value to classification, which must after all be the ultimate basis of a
+genealogical tree.  We can, as Darwin rightly observed, only infer the line
+of descent from the degree of resemblance between single forms.  If we
+regard man as directly derived from primitive forms very far back, we have
+no way of explaining the many points of agreement between him and the
+monkeys in general, and the anthropoid apes in particular.  These must
+remain an inexplicable marvel.
+
+I have thus, I trust, shown that the first class of special theories of
+descent, which assumes that man has developed, parallel with the monkeys,
+but without relation to them, from very low primitive forms cannot be
+upheld, because it fails to take into account the close structural affinity
+of man and monkeys.  I cannot but regard this hypothesis as lamentably
+retrograde, for it makes impossible any application of the facts that have
+been discovered in the course of the anatomical and embryological study of
+man and monkeys, and indeed prejudges investigations of that class as
+pointless.  The whole method is perverted; an unjustifiable theory of
+descent is first formulated with the aid of the imagination, and then we
+are asked to declare that all structural relations between man and monkeys,
+and between the different groups of the latter, are valueless,--the fact
+being that they are the only true basis on which a genealogical tree can be
+constructed.
+
+So much for this most modern method of classification, which has probably
+found adherents because it would deliver us from the relationship to apes
+which many people so much dislike.  In contrast to it we have the second
+class of special hypotheses of descent, which keeps strictly to the nearest
+structural relationships.  This is the only basis that justifies the
+drawing up of a special hypothesis of descent.  If this fundamental
+proposition be recognised, it will be admitted that the doctrine of special
+descent upheld by Haeckel, and set forth in Darwin's "Descent of Man", is
+still valid to-day.  In the genealogical tree, man's place is quite close
+to the anthropoid apes; these again have as their nearest relatives the
+lower Old World monkeys, and their progenitors must be sought among the
+less differentiated Platyrrhine monkeys, whose most important characters
+have been handed on to the present day New World monkeys.  How the
+different genera are to be arranged within the general scheme indicated
+depends in the main on the classificatory value attributed to individual
+characters.  This is particularly true in regard to Pithecanthropus, which
+I consider as the root of a branch which has sprung from the anthropoid ape
+root and has led up to man; the latter I have designated the family of the
+Hominidae.
+
+For the rest, there are, as we have said, various possible ways of
+constructing the narrower genealogy within the limits of this branch
+including men and apes, and these methods will probably continue to change
+with the accumulation of new facts.  Haeckel himself has modified his
+genealogical tree of the Primates in certain details since the publication
+of his "Generelle Morphologie" in 1866, but its general basis remains the
+same.  (Haeckel's latest genealogical tree is to be found in his most
+recent work, "Unsere Ahnenreihe".  Jena, 1908.)  All the special
+genealogical trees drawn up on the lines laid down by Haeckel and Darwin--
+and that of Dubois may be specially mentioned--are based, in general, on
+the close relationship of monkeys and men, although they may vary in
+detail.  Various hypotheses have been formulated on these lines, with
+special reference to the evolution of man.  "Pithecanthropus" is regarded
+by some authorities as the direct ancestor of man, by others as a side-
+track failure in the attempt at the evolution of man.  The problem of the
+monophyletic or polyphyletic origin of the human race has also been much
+discussed.  Sergi (Sergi G. "Europa", 1908.) inclines towards the
+assumption of a polyphyletic origin of the three main races of man, the
+African primitive form of which has given rise also to the gorilla and
+chimpanzee, the Asiatic to the Orang, the Gibbon, and Pithecanthropus. 
+Kollmann regards existing human races as derived from small primitive races
+(pigmies), and considers that Homo primigenius must have arisen in a
+secondary and degenerative manner.
+
+But this is not the place, nor have I the space to criticise the various
+special theories of descent.  One, however, must receive particular notice.
+According to Ameghino, the South American monkeys (Pitheculites) from the
+oldest Tertiary of the Pampas are the forms from which have arisen the
+existing American monkeys on the one hand, and on the other, the extinct
+South American Homunculidae, which are also small forms.  From these last,
+anthropoid apes and man have, he believes, been evolved.  Among the
+progenitors of man, Ameghino reckons the form discovered by him
+(Tetraprothomo), from which a South American primitive man, Homo pampaeus,
+might be directly evolved, while on the other hand all the lower Old World
+monkeys may have arisen from older fossil South American forms
+(Clenialitidae), the distribution of which may be explained by the bridge
+formerly existing between South America and Africa, as may be the
+derivation of all existing human races from Homo pampaeus.  (See Ameghino's
+latest paper, "Notas preliminares sobre el Tetraprothomo argentinus", etc. 
+"Anales del Museo nacional de Buenos Aires", XVI. pages 107-242, 1907.) 
+The fossil forms discovered by Ameghino deserve the most minute
+investigation, as does also the fossil man from South America of which
+Lehmann-Nitsche ("Nouvelles recherches sur la formation pampeenne et
+l'homme fossile de la Republique Argentine".  "Rivista del Museo de la
+Plata", T. XIV. pages 193-488.) has made a thorough study.
+
+It is obvious that, notwithstanding the necessity for fitting man's line of
+descent into the genealogical tree of the Primates, especially the apes,
+opinions in regard to it differ greatly in detail.  This could not be
+otherwise, since the different Primate forms, especially the fossil forms,
+are still far from being exhaustively known.  But one thing remains
+certain,--the idea of the close relationship between man and monkeys set
+forth in Darwin's "Descent of Man".  Only those who deny the many points of
+agreement, the sole basis of classification, and thus of a natural
+genealogical tree, can look upon the position of Darwin and Haeckel as
+antiquated, or as standing on an insufficient foundation.  For such a
+genealogical tree is nothing more than a summarised representation of what
+is known in regard to the degree of resemblance between the different
+forms.
+
+Darwin's work in regard to the descent of man has not been surpassed; the
+more we immerse ourselves in the study of the structural relationships
+between apes and man, the more is our path illumined by the clear light
+radiating from him, and through his calm and deliberate investigation,
+based on a mass of material in the accumulation of which he has never had
+an equal.  Darwin's fame will be bound up for all time with the
+unprejudiced investigation of the question of all questions, the descent of
+the human race.
+
+
+VIII.  CHARLES DARWIN AS AN ANTHROPOLOGIST.
+
+By ERNST HAECKEL.
+Professor of Zoology in the University of Jena.
+
+The great advance that anthropology has made in the second half of the
+nineteenth century is due in the first place, to Darwin's discovery of the
+origin of man.  No other problem in the whole field of research is so
+momentous as that of "Man's place in nature," which was justly described by
+Huxley (1863) as the most fundamental of all questions.  Yet the scientific
+solution of this problem was impossible until the theory of descent had
+been established.
+
+It is now a hundred years since the great French biologist Jean Lamarck
+published his "Philosophie Zoologique".  By a remarkable coincidence the
+year in which that work was issued, 1809, was the year of the birth of his
+most distinguished successor, Charles Darwin.  Lamarck had already
+recognised that the descent of man from a series of other Vertebrates--that
+is, from a series of Ape-like Primates--was essentially involved in the
+general theory of transformation which he had erected on a broad inductive
+basis; and he had sufficient penetration to detect the agencies that had
+been at work in the evolution of the erect bimanous man from the arboreal
+and quadrumanous ape.  He had, however, few empirical arguments to advance
+in support of his hypothesis, and it could not be established until the
+further development of the biological sciences--the founding of comparative
+embryology by Baer (1828) and of the cell-theory by Schleiden and Schwann
+(1838), the advance of physiology under Johannes Muller (1833), and the
+enormous progress of palaeontology and comparative anatomy between 1820 and
+1860--provided this necessary foundation.  Darwin was the first to
+coordinate the ample results of these lines of research.  With no less
+comprehensiveness than discrimination he consolidated them as a basis of a
+modified theory of descent, and associated with them his own theory of
+natural selection, which we take to be distinctive of "Darwinism" in the
+stricter sense.  The illuminating truth of these cumulative arguments was
+so great in every branch of biology that, in spite of the most vehement
+opposition, the battle was won within a single decade, and Darwin secured
+the general admiration and recognition that had been denied to his
+forerunner, Lamarck, up to the hour of his death (1829).
+
+Before, however, we consider the momentous influence that Darwinism has had
+in anthropology, we shall find it useful to glance at its history in the
+course of the last half century, and notice the various theories that have
+contributed to its advance.  The first attempt to give extensive expression
+to the reform of biology by Darwin's work will be found in my "Generelle
+Morphologie" (1866) ("Generelle Morphologie der Organismen", 2 vols.,
+Berlin, 1866.) which was followed by a more popular treatment of the
+subject in my "Naturliche Schopfungsgeschichte (1868) (English translation;
+"The History of Creation", London, 1876.), a compilation from the earlier
+work.  In the first volume of the "Generelle Morphologie" I endeavoured to
+show the great importance of evolution in settling the fundamental
+questions of biological philosophy, especially in regard to comparative
+anatomy.  In the second volume I dealt broadly with the principle of
+evolution, distinguishing ontogeny and phylogeny as its two coordinate main
+branches, and associating the two in the Biogenetic Law.  The Law may be
+formulated thus: "Ontogeny (embryology or the development of the
+individual) is a concise and compressed recapitulation of phylogeny (the
+palaeontological or genealogical series) conditioned by laws of heredity
+and adaptation."  The "Systematic introduction to general evolution," with
+which the second volume of the "Generelle Morphologie" opens, was the first
+attempt to draw up a natural system of organisms (in harmony with the
+principles of Lamarck and Darwin) in the form of a hypothetical pedigree,
+and was provisionally set forth in eight genealogical tables.
+
+In the nineteenth chapter of the "Generelle Morphologie"--a part of which
+has been republished, without any alteration, after a lapse of forty years
+--I made a critical study of Lamarck's theory of descent and of Darwin's
+theory of selection, and endeavoured to bring the complex phenomena of
+heredity and adaptation under definite laws for the first time.  Heredity I
+divided into conservative and progressive:  adaptation into indirect (or
+potential) and direct (or actual).  I then found it possible to give some
+explanation of the correlation of the two physiological functions in the
+struggle for life (selection), and to indicate the important laws of
+divergence (or differentiation) and complexity (or division of labour),
+which are the direct and inevitable outcome of selection.  Finally, I
+marked off dysteleology as the science of the aimless (vestigial, abortive,
+atrophied, and useless) organs and parts of the body.  In all this I worked
+from a strictly monistic standpoint, and sought to explain all biological
+phenomena on the mechanical and naturalistic lines that had long been
+recognised in the study of inorganic nature.  Then (1866), as now, being
+convinced of the unity of nature, the fundamental identity of the agencies
+at work in the inorganic and the organic worlds, I discarded vitalism,
+teleology, and all hypotheses of a mystic character.
+
+It was clear from the first that it was essential, in the monistic
+conception of evolution, to distinguish between the laws of conservative
+and progressive heredity.  Conservative heredity maintains from generation
+to generation the enduring characters of the species.  Each organism
+transmits to its descendants a part of the morphological and physiological
+qualities that it has received from its parents and ancestors.  On the
+other hand, progressive heredity brings new characters to the species--
+characters that were not found in preceding generations.  Each organism may
+transmit to its offspring a part of the morphological and physiological
+features that it has itself acquired, by adaptation, in the course of its
+individual career, through the use or disuse of particular organs, the
+influence of environment, climate, nutrition, etc.  At that time I gave the
+name of "progressive heredity" to this inheritance of acquired characters,
+as a short and convenient expression, but have since changed the term to
+"transformative heredity" (as distinguished from conservative).  This term
+is preferable, as inherited regressive modifications (degeneration,
+retrograde metamorphisis, etc.) come under the same head.
+
+Transformative heredity--or the transmission of acquired characters--is one
+of the most important principles in evolutionary science.  Unless we admit
+it most of the facts of comparative anatomy and physiology are
+inexplicable.  That was the conviction of Darwin no less than of Lamarck,
+of Spencer as well as Virchow, of Huxley as well as Gegenbaur, indeed of
+the great majority of speculative biologists.  This fundamental principle
+was for the first time called in question and assailed in 1885 by August
+Weismann of Freiburg, the eminent zoologist to whom the theory of evolution
+owes a great deal of valuable support, and who has attained distinction by
+his extension of the theory of selection.  In explanation of the phenomena
+of heredity he introduced a new theory, the "theory of the continuity of
+the germ-plasm."  According to him the living substance in all organisms
+consists of two quite distinct kinds of plasm, somatic and germinal.  The
+permanent germ-plasm, or the active substance of the two germ-cells (egg-
+cell and sperm-cell), passes unchanged through a series of generations, and
+is not affected by environmental influences.  The environment modifies only
+the soma-plasm, the organs and tissues of the body.  The modifications that
+these parts undergo through the influence of the environment or their own
+activity (use and habit), do not affect the germ-plasm, and cannot
+therefore be transmitted.
+
+This theory of the continuity of the germ-plasm has been expounded by
+Weismann during the last twenty-four years in a number of able volumes, and
+is regarded by many biologists, such as Mr Francis Galton, Sir E. Ray
+Lankester, and Professor J. Arthur Thomson (who has recently made a
+thoroughgoing defence of it in his important work "Heredity" (London,
+1908.)), as the most striking advance in evolutionary science.  On the
+other hand, the theory has been rejected by Herbert Spencer, Sir W. Turner,
+Gegenbaur, Kolliker, Hertwig, and many others.  For my part I have, with
+all respect for the distinguished Darwinian, contested the theory from the
+first, because its whole foundation seems to me erroneous, and its
+deductions do not seem to be in accord with the main facts of comparative
+morphology and physiology.  Weismann's theory in its entirety is a finely
+conceived molecular hypothesis, but it is devoid of empirical basis.  The
+notion of the absolute and permanent independence of the germ-plasm, as
+distinguished from the soma-plasm, is purely speculative; as is also the
+theory of germinal selection.  The determinants, ids, and idants, are
+purely hypothetical elements.  The experiments that have been devised to
+demonstrate their existence really prove nothing.
+
+It seems to me quite improper to describe this hypothetical structure as
+"Neodarwinism."  Darwin was just as convinced as Lamarck of the
+transmission of acquired characters and its great importance in the scheme
+of evolution.  I had the good fortune to visit Darwin at Down three times
+and discuss with him the main principles of his system, and on each
+occasion we were fully agreed as to the incalculable importance of what I
+call transformative inheritance.  It is only proper to point out that
+Weismann's theory of the germ-plasm is in express contradiction to the
+fundamental principles of Darwin and Lamarck.  Nor is it more acceptable in
+what one may call its "ultradarwinism"--the idea that the theory of
+selection explains everything in the evolution of the organic world.  This
+belief in the "omnipotence of natural selection" was not shared by Darwin
+himself.  Assuredly, I regard it as of the utmost value, as the process of
+natural selection through the struggle for life affords an explanation of
+the mechanical origin of the adapted organisation.  It solves the great
+problem:  how could the finely adapted structure of the animal or plant
+body be formed unless it was built on a preconceived plan?  It thus enables
+us to dispense with the teleology of the metaphysician and the dualist, and
+to set aside the old mythological and poetic legends of creation.  The idea
+had occurred in vague form to the great Empedocles 2000 years before the
+time of Darwin, but it was reserved for modern research to give it ample
+expression.  Nevertheless, natural selection does not of itself give the
+solution of all our evolutionary problems.  It has to be taken in
+conjunction with the transformism of Lamarck, with which it is in complete
+harmony.
+
+The monumental greatness of Charles Darwin, who surpasses every other
+student of science in the nineteenth century by the loftiness of his
+monistic conception of nature and the progressive influence of his ideas,
+is perhaps best seen in the fact that not one of his many successors has
+succeeded in modifying his theory of descent in any essential point or in
+discovering an entirely new standpoint in the interpretation of the organic
+world.  Neither Nageli nor Weismann, neither De Vries nor Roux, has done
+this.  Nageli, in his "Mechanisch-Physiologische Theorie der
+Abstammungslehre" (Munich, 1884.), which is to a great extent in agreement
+with Weismann, constructed a theory of the idioplasm, that represents it
+(like the germ-plasm) as developing continuously in a definite direction
+from internal causes.  But his internal "principle of progress" is at the
+bottom just as teleological as the vital force of the Vitalists, and the
+micellar structure of the idioplasm is just as hypothetical as the
+"dominant" structure of the germ-plasm.  In 1889 Moritz Wagner sought to
+explain the origin of species by migration and isolation, and on that basis
+constructed a special "migration-theory."  This, however, is not out of
+harmony with the theory of selection.  It merely elevates one single factor
+in the theory to a predominant position.  Isolation is only a special case
+of selection, as I had pointed out in the fifteenth chapter of my "Natural
+history of creation".  The "mutation-theory" of De Vries ("Die
+Mutationstheorie", Leipzig, 1903.), that would explain the origin of
+species by sudden and saltatory variations rather than by gradual
+modification, is regarded by many botanists as a great step in advance, but
+it is generally rejected by zoologists.  It affords no explanation of the
+facts of adaptation, and has no causal value.
+
+Much more important than these theories is that of Wilhelm Roux ("Der Kampf
+der Theile im Organismus", Leipzig, 1881.) of "the struggle of parts within
+the organism, a supplementation of the theory of mechanical adaptation." 
+He explains the functional autoformation of the purposive structure by a
+combination of Darwin's principle of selection with Lamarck's idea of
+transformative heredity, and applies the two in conjunction to the facts of
+histology.  He lays stress on the significance of functional adaptation,
+which I had described in 1866, under the head of cumulative adaptation, as
+the most important factor in evolution.  Pointing out its influence in the
+cell-life of the tissues, he puts "cellular selection" above "personal
+selection," and shows how the finest conceivable adaptations in the
+structure of the tissue may be brought about quite mechanically, without
+preconceived plan.  This "mechanical teleology" is a valuable extension of
+Darwin's monistic principle of selection to the whole field of cellular
+physiology and histology, and is wholly destructive of dualistic vitalism.
+
+The most important advance that evolution has made since Darwin and the
+most valuable amplification of his theory of selection is, in my opinion,
+the work of Richard Semon:  "Die Mneme als erhaltendes Prinzip im Wechsel
+des organischen Geschehens" (Leipzig, 1904.).  He offers a psychological
+explanation of the facts of heredity by reducing them to a process of
+(unconscious) memory.  The physiologist Ewald Hering had shown in 1870 that
+memory must be regarded as a general function of organic matter, and that
+we are quite unable to explain the chief vital phenomena, especially those
+of reproduction and inheritance, unless we admit this unconscious memory.
+In my essay "Die Perigenesis der Plastidule" (Berlin, 1876.) I elaborated
+this far-reaching idea, and applied the physical principle of transmitted
+motion to the plastidules, or active molecules of plasm.  I concluded that
+"heredity is the memory of the plastidules, and variability their power of
+comprehension."  This "provisional attempt to give a mechanical explanation
+of the elementary processes of evolution" I afterwards extended by showing
+that sensitiveness is (as Carl Nageli, Ernst Mach, and Albrecht Rau express
+it) a general quality of matter.  This form of panpsychism finds its
+simplest expression in the "trinity of substance."
+
+To the two fundamental attributes that Spinoza ascribed to substance--
+Extension (matter as occupying space) and Cogitation (energy, force)--we
+now add the third fundamental quality of Psychoma (sensitiveness, soul).  I
+further elaborated this trinitarian conception of substance in the
+nineteenth chapter of my "Die Lebenswunder" (1904) ("Wonders of Life",
+London, 1904.), and it seems to me well calculated to afford a monistic
+solution of many of the antitheses of philosophy.
+
+This important Mneme-theory of Semon and the luminous physiological
+experiments and observations associated with it not only throw considerable
+light on transformative inheritance, but provide a sound physiological
+foundation for the biogenetic law.  I had endeavoured to show in 1874, in
+the first chapter of my "Anthropogenie" (English translation; "The
+Evolution of Man", 2 volumes, London, 1879 and 1905.), that this
+fundamental law of organic evolution holds good generally, and that there
+is everywhere a direct causal connection between ontogeny and phylogeny. 
+"Phylogenesis is the mechanical cause of ontogenesis"; in other words, "The
+evolution of the stem or race is--in accordance with the laws of heredity
+and adaptation--the real cause of all the changes that appear, in a
+condensed form, in the development of the individual organism from the
+ovum, in either the embryo or the larva."
+
+It is now fifty years since Charles Darwin pointed out, in the thirteenth
+chapter of his epoch-making "Origin of Species", the fundamental importance
+of embryology in connection with his theory of descent:
+
+"The leading facts in embryology, which are second to none in importance,
+are explained on the principle of variations in the many descendants from
+some one ancient progenitor, having appeared at a not very early period of
+life, and having been inherited at a corresponding period."  ("Origin of
+Species" (6th edition), page 396.)
+
+He then shows that the striking resemblance of the embryos and larvae of
+closely related animals, which in the mature stage belong to widely
+different species and genera, can only be explained by their descent from a
+common progenitor.  Fritz Muller made a closer study of these important
+phenomena in the instructive instance of the Crustacean larva, as given in
+his able work "Fur Darwin" (1864).  (English translation; "Facts and
+Arguments for Darwin", London, 1869.)  I then, in 1872, extended the range
+so as to include all animals (with the exception of the unicellular
+Protozoa) and showed, by means of the theory of the Gastraea, that all
+multicellular, tissue-forming animals--all the Metazoa--develop in
+essentially the same way from the primary germ-layers.  I conceived the
+embryonic form, in which the whole structure consists of only two layers of
+cells, and is known as the gastrula, to be the ontogenetic recapitulation,
+maintained by tenacious heredity, of a primitive common progenitor of all
+the Metazoa, the Gastraea.  At a later date (1895) Monticelli discovered
+that this conjectural ancestral form is still preserved in certain
+primitive Coelenterata--Pemmatodiscus, Kunstleria, and the nearly-related
+Orthonectida.
+
+The general application of the biogenetic law to all classes of animals and
+plants has been proved in my "Systematische Phylogenie".  (3 volumes,
+Berlin, 1894-96.)  It has, however, been frequently challenged, both by
+botanists and zoologists, chiefly owing to the fact that many have failed
+to distinguish its two essential elements, palingenesis and cenogenesis. 
+As early as 1874 I had emphasised, in the first chapter of my "Evolution of
+Man", the importance of discriminating carefully between these two sets of
+phenomena:
+
+"In the evolutionary appreciation of the facts of embryology we must take
+particular care to distinguish sharply and clearly between the primary,
+palingenetic evolutionary processes and the secondary, cenogenetic
+processes.  The palingenetic phenomena, or embryonic RECAPITULATIONS, are
+due to heredity, to the transmission of characters from one generation to
+another.  They enable us to draw direct inferences in regard to
+corresponding structures in the development of the species (e.g. the chorda
+or the branchial arches in all vertebrate embryos).  The cenogenetic
+phenomena, on the other hand, or the embryonic VARIATIONS, cannot be traced
+to inheritance from a mature ancestor, but are due to the adaptation of the
+embryo or the larva to certain conditions of its individual development
+(e.g. the amnion, the allantois, and the vitelline arteries in the embryos
+of the higher vertebrates).  These cenogenetic phenomena are later
+additions; we must not infer from them that there were corresponding
+processes in the ancestral history, and hence they are apt to mislead."
+
+The fundamental importance of these facts of comparative anatomy, atavism,
+and the rudimentary organs, was pointed out by Darwin in the first part of
+his classic work, "The Descent of Man and Selection in Relation to Sex"
+(1871).  ("Descent of Man" (Popular Edition), page 927.)  In the "General
+summary and conclusion" (chapter XXI.) he was able to say, with perfect
+justice:  "He who is not content to look, like a savage, at the phenomena
+of nature as disconnected, cannot any longer believe that man is the work
+of a separate act of creation.  He will be forced to admit that the close
+resemblance of the embryo of man to that, for instance, of a dog--the
+construction of his skull, limbs, and whole frame on the same plan with
+that of other mammals, independently of the uses to which the parts may be
+put--the occasional reappearance of various structures, for instance of
+several muscles, which man does not normally possess, but which are common
+to the Quadrumana--and a crowd of analogous facts--all point in the
+plainest manner to the conclusion that man is the co-descendant with other
+mammals of a common progenitor."
+
+These few lines of Darwin's have a greater scientific value than hundreds
+of those so-called "anthropological treatises," which give detailed
+descriptions of single organs, or mathematical tables with series of
+numbers and what are claimed to be "exact analyses," but are devoid of
+synoptic conclusions and a philosophical spirit.
+
+Charles Darwin is not generally recognised as a great anthropologist, nor
+does the school of modern anthropologists regard him as a leading
+authority.  In Germany, especially, the great majority of the members of
+the anthropological societies took up an attitude of hostility to him from
+the very beginning of the controversy in 1860.  "The Descent of Man" was
+not merely rejected, but even the discussion of it was forbidden on the
+ground that it was "unscientific."
+
+The centre of this inveterate hostility for thirty years--especially after
+1877--was Rudolph Virchow of Berlin, the leading investigator in
+pathological anatomy, who did so much for the reform of medicine by his
+establishment of cellular pathology in 1858.  As a prominent representative
+of "exact" or "descriptive" anthropology, and lacking a broad equipment in
+comparative anatomy and ontogeny, he was unable to accept the theory of
+descent.  In earlier years, and especially during his splendid period of
+activity at Wurzburg (1848-1856), he had been a consistent free-thinker,
+and had in a number of able articles (collected in his "Gesammelte
+Abhandlungen") ("Gesammelte Abhandlungen zur wissenschaftlichen Medizin",
+Berlin, 1856.) upheld the unity of human nature, the inseparability of body
+and spirit.  In later years at Berlin, where he was more occupied with
+political work and sociology (especially after 1866), he abandoned the
+positive monistic position for one of agnosticism and scepticism, and made
+concessions to the dualistic dogma of a spiritual world apart from the
+material frame.
+
+In the course of a Scientific Congress at Munich in 1877 the conflict of
+these antithetic views of nature came into sharp relief.  At this memorable
+Congress I had undertaken to deliver the first address (September 18th) on
+the subject of "Modern evolution in relation to the whole of science."  I
+maintained that Darwin's theory not only solved the great problem of the
+origin of species, but that its implications, especially in regard to the
+nature of man, threw considerable light on the whole of science, and on
+anthropology in particular.  The discovery of the real origin of man by
+evolution from a long series of mammal ancestors threw light on his place
+in nature in every aspect, as Huxley had already shown in his excellent
+lectures of 1863.  Just as all the organs and tissues of the human body had
+originated from those of the nearest related mammals, certain ape-like
+forms, so we were bound to conclude that his mental qualities also had been
+derived from those of his extinct primate ancestor.
+
+This monistic view of the origin and nature of man, which is now admitted
+by nearly all who have the requisite acquaintance with biology, and
+approach the subject without prejudice, encountered a sharp opposition at
+that time.  The opposition found its strongest expression in an address
+that Virchow delivered at Munich four days afterwards (September 22nd), on
+"The freedom of science in the modern State."  He spoke of the theory of
+evolution as an unproved hypothesis, and declared that it ought not to be
+taught in the schools, because it was dangerous to the State.  "We must
+not," he said, "teach that man has descended from the ape or any other
+animal."  When Darwin, usually so lenient in his judgment, read the English
+translation of Virchow's speech, he expressed his disapproval in strong
+terms.  But the great authority that Virchow had--an authority well founded
+in pathology and sociology--and his prestige as President of the German
+Anthropological Society, had the effect of preventing any member of the
+Society from raising serious opposition to him for thirty years.  Numbers
+of journals and treatises repeated his dogmatic statement:  "It is quite
+certain that man has descended neither from the ape nor from any other
+animal."  In this he persisted till his death in 1902.  Since that time the
+whole position of German anthropology has changed.  The question is no
+longer whether man was created by a distinct supernatural act or evolved
+from other mammals, but to which line of the animal hierarchy we must look
+for the actual series of ancestors.  The interested reader will find an
+account of this "battle of Munich" (1877) in my three Berlin lectures
+(April, 1905) ("Der Kampf um die Entwickelungs-Gedanken".  (English
+translation; "Last Words on Evolution", London, 1906.)
+
+The main points in our genealogical tree were clearly recognised by Darwin
+in the sixth chapter of the "Descent of Man".  Lowly organised fishes, like
+the lancelet (Amphioxus), are descended from lower invertebrates resembling
+the larvae of an existing Tunicate (Appendicularia).  From these primitive
+fishes were evolved higher fishes of the ganoid type and others of the type
+of Lepidosiren (Dipneusta).  It is a very small step from these to the
+Amphibia:
+
+"In the class of mammals the steps are not difficult to conceive which led
+from the ancient Monotremata to the ancient Marsupials; and from these to
+the early progenitors of the placental mammals.  We may thus ascend to the
+Lemuridae; and the interval is not very wide from these to the Simiadae. 
+The Simiadae then branched off into two great stems, the New World and Old
+World monkeys; and from the latter, at a remote period, Man, the wonder and
+glory of the Universe, proceeded."  ("Descent of Man" (Popular Edition),
+page 255.)
+
+In these few lines Darwin clearly indicated the way in which we were to
+conceive our ancestral series within the vertebrates.  It is fully
+confirmed by all the arguments of comparative anatomy and embryology, of
+palaeontology and physiology; and all the research of the subsequent forty
+years has gone to establish it.  The deep interest in geology which Darwin
+maintained throughout his life and his complete knowledge of palaeontology
+enabled him to grasp the fundamental importance of the palaeontological
+record more clearly than anthropologists and zoologists usually do.
+
+There has been much debate in subsequent decades whether Darwin himself
+maintained that man was descended from the ape, and many writers have
+sought to deny it.  But the lines I have quoted verbatim from the
+conclusion of the sixth chapter of the "Descent of Man" (1871) leave no
+doubt that he was as firmly convinced of it as was his great precursor Jean
+Lamarck in 1809.  Moreover, Darwin adds, with particular explicitness, in
+the "general summary and conclusion" (chapter XXI.) of that standard work
+("Descent of Man", page 930.):
+
+"By considering the embryological structure of man--the homologies which he
+presents with the lower animals,--the rudiments which he retains,--and the
+reversions to which he is liable, we can partly recall in imagination the
+former condition of our early progenitors; and can approximately place them
+in their proper place in the zoological series.  We thus learn that man is
+descended from a hairy, tailed quadruped, probably arboreal in its habits,
+and an inhabitant of the Old World.  This creature, if its whole structure
+had been examined by a naturalist, would have been classed amongst the
+Quadrumana, as surely as the still more ancient progenitor of the Old and
+New World monkeys."
+
+These clear and definite lines leave no doubt that Darwin--so critical and
+cautious in regard to important conclusions--was quite as firmly convinced
+of the descent of man from the apes (the Catarrhinae, in particular) as
+Lamarck was in 1809 and Huxley in 1863.
+
+It is to be noted particularly that, in these and other observations on the
+subject, Darwin decidedly assumes the monophyletic origin of the mammals,
+including man.  It is my own conviction that this is of the greatest
+importance.  A number of difficult questions in regard to the development
+of man, in respect of anatomy, physiology, psychology, and embryology, are
+easily settled if we do not merely extend our progonotaxis to our nearest
+relatives, the anthropoid apes and the tailed monkeys from which these have
+descended, but go further back and find an ancestor in the group of the
+Lemuridae, and still further back to the Marsupials and Monotremata.  The
+essential identity of all the Mammals in point of anatomical structure and
+embryonic development--in spite of their astonishing differences in
+external appearance and habits of life--is so palpably significant that
+modern zoologists are agreed in the hypothesis that they have all sprung
+from a common root, and that this root may be sought in the earlier
+Palaeozoic Amphibia.
+
+The fundamental importance of this comparative morphology of the Mammals,
+as a sound basis of scientific anthropology, was recognised just before the
+beginning of the nineteenth century, when Lamarck first emphasised (1794)
+the division of the animal kingdom into Vertebrates and Invertebrates. 
+Even thirteen years earlier (1781), when Goethe made a close study of the
+mammal skeleton in the Anatomical Institute at Jena, he was intensely
+interested to find that the composition of the skull was the same in man as
+in the other mammals.  His discovery of the os intermaxillare in man
+(1784), which was contradicted by most of the anatomists of the time, and
+his ingenious "vertebral theory of the skull," were the splendid fruit of
+his morphological studies.  They remind us how Germany's greatest
+philosopher and poet was for many years ardently absorbed in the
+comparative anatomy of man and the mammals, and how he divined that their
+wonderful identity in structure was no mere superficial resemblance, but
+pointed to a deep internal connection.  In my "Generelle Morphologie"
+(1866), in which I published the first attempts to construct phylogenetic
+trees, I have given a number of remarkable theses of Goethe, which may be
+called "phyletic prophecies."  They justify us in regarding him as a
+precursor of Darwin.
+
+In the ensuing forty years I have made many conscientious efforts to
+penetrate further along that line of anthropological research that was
+opened up by Goethe, Lamarck, and Darwin.  I have brought together the many
+valuable results that have constantly been reached in comparative anatomy,
+physiology, ontogeny, and palaeontology, and maintained the effort to
+reform the classification of animals and plants in an evolutionary sense.
+The first rough drafts of pedigrees that were published in the "Generelle
+Morphologie" have been improved time after time in the ten editions of my
+"Naturaliche Schopfungsgeschichte" (1868-1902).  (English translation; "The
+History of Creation", London, 1876.)  A sounder basis for my phyletic
+hypotheses, derived from a discriminating combination of the three great
+records--morphology, ontogeny, and palaeontology--was provided in the three
+volumes of my "Systematische Phylogenie (Berlin, 1894-96.) (1894 Protists
+and Plants, 1895 Vertebrates, 1896 Invertebrates).  In my "Anthropogenie"
+(Leipzig, 1874, 5th edition 1905.  English translation; "The Evolution of
+Man", London, 1905.) I endeavoured to employ all the known facts of
+comparative ontogeny (embryology) for the purpose of completing my scheme
+of human phylogeny (evolution).  I attempted to sketch the historical
+development of each organ of the body, beginning with the most elementary
+structures in the germ-layers of the Gastraea.  At the same time I drew up
+a corrected statement of the most important steps in the line of our
+ancestral series.
+
+At the fourth International Congress of Zoology at Cambridge (August 26th,
+1898) I delivered an address on "Our present knowledge of the Descent of
+Man."  It was translated into English, enriched with many valuable notes
+and additions, by my friend and pupil in earlier days Dr Hans Gadow
+(Cambridge), and published under the title:  "The Last Link; our present
+knowledge of the Descent of Man".  (London, 1898.)  The determination of
+the chief animal forms that occur in the line of our ancestry is there
+restricted to thirty types, and these are distributed in six main groups.
+
+The first half of this "Progonotaxis hominis," which has no support from
+fossil evidence, comprises three groups:  (i) Protista (unicellular
+organisms, 1-5:  (ii) Invertebrate Metazoa (Coelenteria 6-8, Vermalia 9-
+11):  (iii) Monorrhine Vertebrates (Acrania 12-13, Cyclostoma 14-15).  The
+second half, which is based on fossil records, also comprises three groups: 
+(iv) Palaeozoic cold-blooded Craniota (Fishes 16-18, Amphibia 19, Reptiles
+20:  (v) Mesozoic Mammals (Monotrema 21, Marsupialia 22, Mallotheria 23): 
+(vi) Cenozoic Primates (Lemuridae 24-25, Tailed Apes 26-27, Anthropomorpha
+28-30).  An improved and enlarged edition of this hypothetic "Progonotaxis
+hominis" was published in 1908, in my essay "Unsere Ahnenreihe". 
+("Festschrift zur 350-jahrigen Jubelfeier der Thuringer Universitat Jena". 
+Jena, 1908.)
+
+If I have succeeded in furthering, in some degree, by these anthropological
+works, the solution of the great problem of Man's place in nature, and
+particularly in helping to trace the definite stages in our ancestral
+series, I owe the success, not merely to the vast progress that biology has
+made in the last half century, but largely to the luminous example of the
+great investigators who have applied themselves to the problem, with so
+much assiduity and genius, for a century and a quarter--I mean Goethe and
+Lamarck, Gegenbaur and Huxley, but, above all, Charles Darwin.  It was the
+great genius of Darwin that first brought together the scattered material
+of biology and shaped it into that symmetrical temple of scientific
+knowledge, the theory of descent.  It was Darwin who put the crown on the
+edifice by his theory of natural selection.  Not until this broad inductive
+law was firmly established was it possible to vindicate the special
+conclusion, the descent of man from a series of other Vertebrates.  By his
+illuminating discovery Darwin did more for anthropology than thousands of
+those writers, who are more specifically titled anthropologists, have done
+by their technical treatises.  We may, indeed, say that it is not merely as
+an exact observer and ingenious experimenter, but as a distinguished
+anthropologist and far-seeing thinker, that Darwin takes his place among
+the greatest men of science of the nineteenth century.
+
+To appreciate fully the immortal merit of Darwin in connection with
+anthropology, we must remember that not only did his chief work, "The
+Origin of Species", which opened up a new era in natural history in 1859,
+sustain the most virulent and widespread opposition for a lengthy period,
+but even thirty years later, when its principles were generally recognised
+and adopted, the application of them to man was energetically contested by
+many high scientific authorities.  Even Alfred Russel Wallace, who
+discovered the principle of natural selection independently in 1858, did
+not concede that it was applicable to the higher mental and moral qualities
+of man.  Dr Wallace still holds a spiritualist and dualist view of the
+nature of man, contending that he is composed of a material frame
+(descended from the apes) and an immortal immaterial soul (infused by a
+higher power).  This dual conception, moreover, is still predominant in the
+wide circles of modern theology and metaphysics, and has the general and
+influential adherence of the more conservative classes of society.
+
+In strict contradiction to this mystical dualism, which is generally
+connected with teleology and vitalism, Darwin always maintained the
+complete unity of human nature, and showed convincingly that the
+psychological side of man was developed, in the same way as the body, from
+the less advanced soul of the anthropoid ape, and, at a still more remote
+period, from the cerebral functions of the older vertebrates.  The eighth
+chapter of the "Origin of Species", which is devoted to instinct, contains
+weighty evidence that the instincts of animals are subject, like all other
+vital processes, to the general laws of historic development.  The special
+instincts of particular species were formed by adaptation, and the
+modifications thus acquired were handed on to posterity by heredity; in
+their formation and preservation natural selection plays the same part as
+in the transformation of every other physiological function.  The higher
+moral qualities of civilised man have been derived from the lower mental
+functions of the uncultivated barbarians and savages, and these in turn
+from the social instincts of the mammals.  This natural and monistic
+psychology of Darwin's was afterwards more fully developed by his friend
+George Romanes in his excellent works "Mental Evolution in Animals" and
+"Mental Evolution in Man".  (London, 1885; 1888.)
+
+Many valuable and most interesting contributions to this monistic
+psychology of man were made by Darwin in his fine work on "The Descent of
+Man and Selection in Relation to Sex", and again in his supplementary work,
+"The Expression of the Emotions in Man and Animals".  To understand the
+historical development of Darwin's anthropology one must read his life and
+the introduction to "The Descent of Man".  From the moment that he was
+convinced of the truth of the principle of descent--that is to say, from
+his thirtieth year, in 1838--he recognised clearly that man could not be
+excluded from its range.  He recognised as a logical necessity the
+important conclusion that "man is the co-descendant with other species of
+some ancient, lower, and extinct form."  For many years he gathered notes
+and arguments in support of this thesis, and for the purpose of showing the
+probable line of man's ancestry.  But in the first edition of "The Origin
+of Species" (1859) he restricted himself to the single line, that by this
+work "light would be thrown on the origin of man and his history."  In the
+fifty years that have elapsed since that time the science of the origin and
+nature of man has made astonishing progress, and we are now fairly agreed
+in a monistic conception of nature that regards the whole universe,
+including man, as a wonderful unity, governed by unalterable and eternal
+laws.  In my philosophical book "Die Weltratsel" (1899) ("The Riddle of the
+Universe", London, 1900.) and in the supplementary volume "Die
+Lebenswunder" (1904) "The Wonders of Life", London, 1904.), I have
+endeavoured to show that this pure monism is securely established, and that
+the admission of the all-powerful rule of the same principle of evolution
+throughout the universe compels us to formulate a single supreme law--the
+all-embracing "Law of Substance," or the united laws of the constancy of
+matter and the conservation of energy.  We should never have reached this
+supreme general conception if Charles Darwin--a "monistic philosopher" in
+the true sense of the word--had not prepared the way by his theory of
+descent by natural selection, and crowned the great work of his life by the
+association of this theory with a naturalistic anthropology.
+
+
+IX.  SOME PRIMITIVE THEORIES OF THE ORIGIN OF MAN.
+
+By J.G. FRAZER.
+Fellow of Trinity College, Cambridge.
+
+On a bright day in late autumn a good many years ago I had ascended the
+hill of Panopeus in Phocis to examine the ancient Greek fortifications
+which crest its brow.  It was the first of November, but the weather was
+very hot; and when my work among the ruins was done, I was glad to rest
+under the shade of a clump of fine holly-oaks, to inhale the sweet
+refreshing perfume of the wild thyme which scented all the air, and to
+enjoy the distant prospects, rich in natural beauty, rich too in memories
+of the legendary and historic past.  To the south the finely-cut peak of
+Helicon peered over the low intervening hills.  In the west loomed the
+mighty mass of Parnassus, its middle slopes darkened by pine-woods like
+shadows of clouds brooding on the mountain-side; while at its skirts
+nestled the ivy-mantled walls of Daulis overhanging the deep glen, whose
+romantic beauty accords so well with the loves and sorrows of Procne and
+Philomela, which Greek tradition associated with the spot.  Northwards,
+across the broad plain to which the hill of Panopeus descends, steep and
+bare, the eye rested on the gap in the hills through which the Cephissus
+winds his tortuous way to flow under grey willows, at the foot of barren
+stony hills, till his turbid waters lose themselves, no longer in the vast
+reedy swamps of the now vanished Copaic Lake, but in the darkness of a
+cavern in the limestone rock.  Eastward, clinging to the slopes of the
+bleak range of which the hill of Panopeus forms part, were the ruins of
+Chaeronea, the birthplace of Plutarch; and out there in the plain was
+fought the disastrous battle which laid Greece at the feet of Macedonia. 
+There, too, in a later age East and West met in deadly conflict, when the
+Roman armies under Sulla defeated the Asiatic hosts of Mithridates.  Such
+was the landscape spread out before me on one of those farewell autumn days
+of almost pathetic splendour, when the departing summer seems to linger
+fondly, as if loth to resign to winter the enchanted mountains of Greece. 
+Next day the scene had changed:  summer was gone.  A grey November mist
+hung low on the hills which only yesterday had shone resplendent in the
+sun, and under its melancholy curtain the dead flat of the Chaeronean
+plain, a wide treeless expanse shut in by desolate slopes, wore an aspect
+of chilly sadness befitting the battlefield where a nation's freedom was
+lost.
+
+But crowded as the prospect from Panopeus is with memories of the past, the
+place itself, now so still and deserted, was once the scene of an event
+even more ancient and memorable, if Greek story-tellers can be trusted. 
+For here, they say, the sage Prometheus created our first parents by
+fashioning them, like a potter, out of clay.  (Pausanias X. 4.4.  Compare
+Apollodorus, "Bibliotheca", I. 7. 1; Ovid, "Metamorph." I. 82 sq.; Juvenal,
+"Sat". XIV. 35.  According to another version of the tale, this creation of
+mankind took place not at Panopeus, but at Iconium in Lycaonia.  After the
+original race of mankind had been destroyed in the great flood of
+Deucalion, the Greek Noah, Zeus commanded Prometheus and Athena to create
+men afresh by moulding images out of clay, breathing the winds into them,
+and making them live.  See "Etymologicum Magnum", s.v. "'Ikonion", pages
+470 sq.  It is said that Prometheus fashioned the animals as well as men,
+giving to each kind of beast its proper nature.  See Philemon, quoted by
+Stobaeus, "Florilegium" II. 27.  The creation of man by Prometheus is
+figured on ancient works of art.  See J. Toutain, "Etudes de Mythologie et
+d'Histoire des Religions Antiques" (Paris, 1909), page 190.  According to
+Hesiod ("Works and Days", 60 sqq.) it was Hephaestus who at the bidding of
+Zeus moulded the first woman out of moist earth.)  The very spot where he
+did so can still be seen.  It is a forlorn little glen or rather hollow
+behind the hill of Panopeus, below the ruined but still stately walls and
+towers which crown the grey rocks of the summit.  The glen, when I visited
+it that hot day after the long drought of summer, was quite dry; no water
+trickled down its bushy sides, but in the bottom I found a reddish
+crumbling earth, a relic perhaps of the clay out of which the potter
+Prometheus moulded the Greek Adam and Eve.  In a volume dedicated to the
+honour of one who has done more than any other in modern times to shape the
+ideas of mankind as to their origin it may not be out of place to recall
+this crude Greek notion of the creation of the human race, and to compare
+or contrast it with other rudimentary speculations of primitive peoples on
+the same subject, if only for the sake of marking the interval which
+divides the childhood from the maturity of science.
+
+The simple notion that the first man and woman were modelled out of clay by
+a god or other superhuman being is found in the traditions of many peoples. 
+This is the Hebrew belief recorded in Genesis:  "The Lord God formed man of
+the dust of the ground, and breathed into his nostrils the breath of life;
+and man became a living soul."  (Genesis ii.7.)  To the Hebrews this
+derivation of our species suggested itself all the more naturally because
+in their language the word for "ground" (adamah) is in form the feminine of
+the word for man (adam).  (S.R. Driver and W.H.Bennett, in their
+commentaries on Genesis ii. 7.)  From various allusions in Babylonian
+literature it would seem that the Babylonians also conceived man to have
+been moulded out of clay.  (H. Zimmern, in E. Schrader's "Die
+Keilinschriften und das Alte Testament"3 (Berlin, 1902), page 506.) 
+According to Berosus, the Babylonian priest whose account of creation has
+been preserved in a Greek version, the god Bel cut off his own head, and
+the other gods caught the flowing blood, mixed it with earth, and fashioned
+men out of the bloody paste; and that, they said, is why men are so wise,
+because their mortal clay is tempered with divine blood.  (Eusebius,
+"Chronicon", ed. A. Schoene, Vol. I. (Berlin, 1875), col. 16.)  In Egyptian
+mythology Khnoumou, the Father of the gods, is said to have moulded men out
+of clay.  (G. Maspero, "Histoire Ancienne des Peuples de l'Orient
+Classique", I. (Paris, 1895), page 128.)  We cannot doubt that such crude
+conceptions of the origin of our race were handed down to the civilised
+peoples of antiquity by their savage or barbarous forefathers.  Certainly
+stories of the same sort are known to be current among savages and
+barbarians.
+
+Thus the Australian blacks in the neighbourhood of Melbourne said that
+Pund-jel, the creator, cut three large sheets of bark with his big knife. 
+On one of these he placed some clay and worked it up with his knife into a
+proper consistence.  He then laid a portion of the clay on one of the other
+pieces of bark and shaped it into a human form; first he made the feet,
+then the legs, then the trunk, the arms, and the head.  Thus he made a clay
+man on each of the two pieces of bark; and being well pleased with them he
+danced round them for joy.  Next he took stringy bark from the Eucalyptus
+tree, made hair of it, and stuck it on the heads of his clay men.  Then he
+looked at them again, was pleased with his work, and again danced round
+them for joy.  He then lay down on them, blew his breath hard into their
+mouths, their noses, and their navels; and presently they stirred, spoke,
+and rose up as full-grown men.  (R. Brough Smyth, "The Aborigines of
+Victoria" (Melbourne, 1878), I. 424.  This and many of the following
+legends of creation have been already cited by me in a note on Pausanias X.
+4. 4 ("Pausanias's Description of Greece, translated with a Commentary"
+(London, 1898), Vol V. pages 220 sq.).)  The Maoris of New Zealand say that
+Tiki made man after his own image.  He took red clay, kneaded it, like the
+Babylonian Bel, with his own blood, fashioned it in human form, and gave
+the image breath.  As he had made man in his own likeness he called him
+Tiki-ahua or Tiki's likeness.  (R. Taylor "Te Ika A Maui, or New Zealand
+and its Inhabitants", Second Edition (London, 1870), page 117.  Compare E.
+Shortland, "Maori Religion and Mythology" (London, 1882), pages 21 sq.)  A
+very generally received tradition in Tahiti was that the first human pair
+was made by Taaroa, the chief god.  They say that after he had formed the
+world he created man out of red earth, which was also the food of mankind
+until bread-fruit was produced.  Further, some say that one day Taaroa
+called for the man by name, and when he came he made him fall asleep.  As
+he slept, the creator took out one of his bones (ivi) and made a woman of
+it, whom he gave to the man to be his wife, and the pair became the
+progenitors of mankind.  This narrative was taken down from the lips of the
+natives in the early years of the mission to Tahiti.  The missionary who
+records it observes:  "This always appeared to me a mere recital of the
+Mosaic account of creation, which they had heard from some European, and I
+never placed any reliance on it, although they have repeatedly told me it
+was a tradition among them before any foreigner arrived.  Some have also
+stated that the woman's name was Ivi, which would be by them pronounced as
+if written "Eve".  "Ivi" is an aboriginal word, and not only signifies a
+bone, but also a widow, and a victim slain in war.  Notwithstanding the
+assertion of the natives, I am disposed to think that "Ivi", or Eve, is the
+only aboriginal part of the story, as far as it respects the mother of the
+human race.  (W. Ellis, "Polynesian Researches", Second Edition (London,
+1832), I. 110 sq.  "Ivi" or "iwi" is the regular word for "bone" in the
+various Polynesian languages.  See E. Tregear, "The Maori-Polynesian
+Comparative Dictionary" (Wellington, New Zealand, 1891), page 109.) 
+However, the same tradition has been recorded in other parts of Polynesia
+besides Tahiti.  Thus the natives of Fakaofo or Bowditch Island say that
+the first man was produced out of a stone.  After a time he bethought him
+of making a woman.  So he gathered earth and moulded the figure of a woman
+out of it, and having done so he took a rib out of his left side and thrust
+it into the earthen figure, which thereupon started up a live woman.  He
+called her Ivi (Eevee) or "rib" and took her to wife, and the whole human
+race sprang from this pair.  (G. Turner, "Samoa" (London, 1884), pages 267
+sq.)  The Maoris also are reported to believe that the first woman was made
+out of the first man's ribs.  (J.L. Nicholas, "Narrative of a Voyage to New
+Zealand" (London, 1817), I. 59, who writes "and to add still more to this
+strange coincidence, the general term for bone is 'Hevee'.")  This wide
+diffusion of the story in Polynesia raises a doubt whether it is merely, as
+Ellis thought, a repetition of the Biblical narrative learned from
+Europeans.  In Nui, or Netherland Island, it was the god Aulialia who made
+earthen models of a man and woman, raised them up, and made them live.  He
+called the man Tepapa and the woman Tetata.  (G. Turner, "Samoa", pages 300
+sq.)
+
+In the Pelew Islands they say that a brother and sister made men out of
+clay kneaded with the blood of various animals, and that the characters of
+these first men and of their descendants were determined by the characters
+of the animals whose blood had been kneaded with the primordial clay; for
+instance, men who have rat's blood in them are thieves, men who have
+serpent's blood in them are sneaks, and men who have cock's blood in them
+are brave.  (J. Kubary, "Die Religion der Pelauer", in A. Bastian's
+"Allerlei aus Volks- und Menschenkunde" (Berlin, 1888), I. 3, 56.) 
+According to a Melanesian legend, told in Mota, one of the Banks Islands,
+the hero Qat moulded men of clay, the red clay from the marshy river-side
+at Vanua Lava.  At first he made men and pigs just alike, but his brothers
+remonstrated with him, so he beat down the pigs to go on all fours and made
+men walk upright.  Qat fashioned the first woman out of supple twigs, and
+when she smiled he knew she was a living woman.  (R.H. Codrington, "The
+Melanesians" (Oxford, 1891), page 158.)  A somewhat different version of
+the Melanesian story is told at Lakona, in Santa Maria.  There they say
+that Qat and another spirit ("vui") called Marawa both made men.  Qat made
+them out of the wood of dracaena-trees.  Six days he worked at them,
+carving their limbs and fitting them together.  Then he allowed them six
+days to come to life.  Three days he hid them away, and three days more he
+worked to make them live.  He set them up and danced to them and beat his
+drum, and little by little they stirred, till at last they could stand all
+by themselves.  Then Qat divided them into pairs and called each pair
+husband and wife.  Marawa also made men out of a tree, but it was a
+different tree, the tavisoviso.  He likewise worked at them six days, beat
+his drum, and made them live, just as Qat did.  But when he saw them move,
+he dug a pit and buried them in it for six days, and then, when he scraped
+away the earth to see what they were doing, he found them all rotten and
+stinking.  That was the origin of death.  (R.H. Codrington op. cit., pages
+157 sq.)
+
+The inhabitants of Noo-Hoo-roa, in the Kei Islands say that their ancestors
+were fashioned out of clay by the supreme god, Dooadlera, who breathed life
+into the clay figures.  (C.M. Pleyte, "Ethnographische Beschrijving der
+Kei-Eilanden", "Tijdschrift van het Nederlandsch Aardrijkskundig
+Genootschap", Tweede Serie X. (1893), page 564.)  The aborigines of
+Minahassa, in the north of Celebes, say that two beings called Wailan
+Wangko and Wangi were alone on an island, on which grew a cocoa-nut tree. 
+Said Wailan Wangko to Wangi, "Remain on earth while I climb up the tree." 
+Said Wangi to Wailan Wangko, "Good."  But then a thought occurred to Wangi
+and he climbed up the tree to ask Wailan Wangko why he, Wangi, should
+remain down there all alone.  Said Wailan Wangko to Wangi, "Return and take
+earth and make two images, a man and a woman."  Wangi did so, and both
+images were men who could move but could not speak.  So Wangi climbed up
+the tree to ask Wailan Wangko, "How now?  The two images are made, but they
+cannot speak."  Said Wailan Wangko to Wangi, "Take this ginger and go and
+blow it on the skulls and the ears of these two images, that they may be
+able to speak; call the man Adam and the woman Ewa."  (N. Graafland "De
+Minahassa" (Rotterdam, 1869), I. pages 96 sq.)  In this narrative the names
+of the man and woman betray European influence, but the rest of the story
+may be aboriginal.  The Dyaks of Sakarran in British Borneo say that the
+first man was made by two large birds.  At first they tried to make men out
+of trees, but in vain.  Then they hewed them out of rocks, but the figures
+could not speak.  Then they moulded a man out of damp earth and infused
+into his veins the red gum of the kumpang-tree.  After that they called to
+him and he answered; they cut him and blood flowed from his wounds. 
+(Horsburgh, quoted by H. Ling Roth, "The Natives of Sarawak and of British
+North Borneo" (London, 1896), I. pages 299 sq.  Compare The Lord Bishop of
+Labuan, "On the Wild Tribes of the North-West Coast of Borneo,"
+"Transactions of the Ethnological Society of London", New Series, II.
+(1863), page 27.)
+
+The Kumis of South-Eastern India related to Captain Lewin, the Deputy
+Commissioner of Hill Tracts, the following tradition of the creation of
+man.  "God made the world and the trees and the creeping things first, and
+after that he set to work to make one man and one woman, forming their
+bodies of clay; but each night, on the completion of his work, there came a
+great snake, which, while God was sleeping, devoured the two images.  This
+happened twice or thrice, and God was at his wit's end, for he had to work
+all day, and could not finish the pair in less than twelve hours; besides,
+if he did not sleep, he would be no good," said Captain Lewin's informant. 
+"If he were not obliged to sleep, there would be no death, nor would
+mankind be afflicted with illness.  It is when he rests that the snake
+carries us off to this day.  Well, he was at his wit's end, so at last he
+got up early one morning and first made a dog and put life into it, and
+that night, when he had finished the images, he set the dog to watch them,
+and when the snake came, the dog barked and frightened it away.  This is
+the reason at this day that when a man is dying the dogs begin to howl; but
+I suppose God sleeps heavily now-a-days, or the snake is bolder, for men
+die all the same."  (Capt. T.H. Lewin, "Wild Races of South-Eastern India"
+(London, 1870), pages 224-26.)  The Khasis of Assam tell a similar tale. 
+(A. Bastian, "Volkerstamme am Brahmaputra und verwandtschaftliche Nachbarn"
+(Berlin, 1883), page 8; Major P.R.T. Gurdon, "The Khasis" (London, 1907),
+page 106.)
+
+The Ewe-speaking tribes of Togo-land, in West Africa, think that God still
+makes men out of clay.  When a little of the water with which he moistens
+the clay remains over, he pours it on the ground and out of that he makes
+the bad and disobedient people.  When he wishes to make a good man he makes
+him out of good clay; but when he wishes to make a bad man, he employs only
+bad clay for the purpose.  In the beginning God fashioned a man and set him
+on the earth; after that he fashioned a woman.  The two looked at each
+other and began to laugh, whereupon God sent them into the world.  (J.
+Spieth, "Die Ewe-Stamme, Material zur Kunde des Ewe-Volkes in Deutsch-Togo"
+(Berlin, 1906), pages 828, 840.)  The Innuit or Esquimaux of Point Barrow,
+in Alaska, tell of a time when there was no man in the land, till a spirit
+named "a se lu", who resided at Point Barrow, made a clay man, set him up
+on the shore to dry, breathed into him and gave him life.  ("Report of the
+International Expedition to Point Barrow" (Washington, 1885), page 47.) 
+Other Esquimaux of Alaska relate how the Raven made the first woman out of
+clay to be a companion to the first man; he fastened water-grass to the
+back of the head to be hair, flapped his wings over the clay figure, and it
+arose, a beautiful young woman.  (E.W. Nelson, "The Eskimo about Bering
+Strait", "Eighteenth Annual Report of the Bureau of American Ethnology",
+Part I. (Washington, 1899), page 454.)  The Acagchemem Indians of
+California said that a powerful being called Chinigchinich created man out
+of clay which he found on the banks of a lake; male and female created he
+them, and the Indians of the present day are their descendants.  (Friar
+Geronimo Boscana, "Chinigchinich", appended to (A. Robinson's) "Life in
+California" (New York, 1846), page 247.)  A priest of the Natchez Indians
+in Louisiana told Du Pratz "that God had kneaded some clay, such as that
+which potters use and had made it into a little man; and that after
+examining it, and finding it well formed, he blew up his work, and
+forthwith that little man had life, grew, acted, walked, and found himself
+a man perfectly well shaped."  As to the mode in which the first woman was
+created, the priest had no information, but thought she was probably made
+in the same way as the first man; so Du Pratz corrected his imperfect
+notions by reference to Scripture.  (M. Le Page Du Pratz, "The History of
+Louisiana" (London, 1774), page 330.)  The Michoacans of Mexico said that
+the great god Tucapacha first made man and woman out of clay, but that when
+the couple went to bathe in a river they absorbed so much water that the
+clay of which they were composed all fell to pieces.  Then the creator went
+to work again and moulded them afresh out of ashes, and after that he
+essayed a third time and made them of metal.  This last attempt succeeded. 
+The metal man and woman bathed in the river without falling to pieces, and
+by their union they became the progenitors of mankind.  (A. de Herrera,
+"General History of the vast Continent and Islands of America", translated
+into English by Capt. J. Stevens (London, 1725, 1726), III. 254; Brasseur
+de Bourbourg, "Histoire des Nations Civilisees du Mexique et de l'Amerique-
+Centrale" (Paris, 1857--1859), III. 80 sq; compare id. I. 54 sq.)
+
+According to a legend of the Peruvian Indians, which was told to a Spanish
+priest in Cuzco about half a century after the conquest, it was in
+Tiahuanaco that man was first created, or at least was created afresh after
+the deluge.  "There (in Tiahuanaco)," so runs the legend, "the Creator
+began to raise up the people and nations that are in that region, making
+one of each nation of clay, and painting the dresses that each one was to
+wear; those that were to wear their hair, with hair, and those that were to
+be shorn, with hair cut.  And to each nation was given the language, that
+was to be spoken, and the songs to be sung, and the seeds and food that
+they were to sow.  When the Creator had finished painting and making the
+said nations and figures of clay, he gave life and soul to each one, as
+well men as women, and ordered that they should pass under the earth. 
+Thence each nation came up in the places to which he ordered them to go." 
+(E.J. Payne, "History of the New World called America", I. (Oxford, 1892),
+page 462.)
+
+These examples suffice to prove that the theory of the creation of man out
+of dust or clay has been current among savages in many parts of the world.
+But it is by no means the only explanation which the savage philosopher has
+given of the beginnings of human life on earth.  Struck by the resemblances
+which may be traced between himself and the beasts, he has often supposed,
+like Darwin himself, that mankind has been developed out of lower forms of
+animal life.  For the simple savage has none of that high notion of the
+transcendant dignity of man which makes so many superior persons shrink
+with horror from the suggestion that they are distant cousins of the
+brutes.  He on the contrary is not too proud to own his humble relations;
+indeed his difficulty often is to perceive the distinction between him and
+them.  Questioned by a missionary, a Bushman of more than average
+intelligence "could not state any difference between a man and a brute--he
+did not know but a buffalo might shoot with bows and arrows as well as man,
+if it had them."  (Reverend John Campbell, "Travels in South Africa"
+(London, 1822, II. page 34.)  When the Russians first landed on one of the
+Alaskan islands, the natives took them for cuttle-fish "on account of the
+buttons on their clothes."  (I. Petroff, "Report on the Population,
+Industries, and Resources of Alaska", page 145.)  The Giliaks of the Amoor
+think that the outward form and size of an animal are only apparent; in
+substance every beast is a real man, just like a Giliak himself, only
+endowed with an intelligence and strength, which often surpass those of
+mere ordinary human beings.  (L. Sternberg, "Die Religion der Giljaken",
+"Archiv fur Religionswissenschaft", VIII. (1905), page 248.)  The
+Borororos, an Indian tribe of Brazil, will have it that they are parrots of
+a gorgeous red plumage which live in their native forests.  Accordingly
+they treat the birds as their fellow-tribesmen, keeping them in captivity,
+refusing to eat their flesh, and mourning for them when they die.  (K. von
+den Steinen, "Unter den Naturvolkern Zentral-Brasiliens" (Berlin, 1894),
+pages 352 sq., 512.)
+
+This sense of the close relationship of man to the lower creation is the
+essence of totemism, that curious system of superstition which unites by a
+mystic bond a group of human kinsfolk to a species of animals or plants. 
+Where that system exists in full force, the members of a totem clan
+identify themselves with their totem animals in a way and to an extent
+which we find it hard even to imagine.  For example, men of the Cassowary
+clan in Mabuiag think that cassowaries are men or nearly so.  "Cassowary,
+he all same as relation, he belong same family," is the account they give
+of their relationship with the long-legged bird.  Conversely they hold that
+they themselves are cassowaries for all practical purposes.  They pride
+themselves on having long thin legs like a cassowary.  This reflection
+affords them peculiar satisfaction when they go out to fight, or to run
+away, as the case may be; for at such times a Cassowary man will say to
+himself, "My leg is long and thin, I can run and not feel tired; my legs
+will go quickly and the grass will not entangle them."  Members of the
+Cassowary clan are reputed to be pugnacious, because the cassowary is a
+bird of very uncertain temper and can kick with extreme violence.  (A.C.
+Haddon, "The Ethnography of the Western Tribe of Torres Straits", "Journal
+of the Anthropological Institute", XIX. (1890), page 393; "Reports of the
+Cambridge Anthropological Expedition to Torres Straits", V. (Cambridge,
+1904), pages 166, 184.)  So among the Ojibways men of the Bear clan are
+reputed to be surly and pugnacious like bears, and men of the Crane clan to
+have clear ringing voices like cranes.  (W.W. Warren, "History of the
+Ojibways", "Collections of the Minnesota Historical Society", V. (Saint
+Paul, Minn. 1885), pages 47, 49.)  Hence the savage will often speak of his
+totem animal as his father or his brother, and will neither kill it himself
+nor allow others to do so, if he can help it.  For example, if somebody
+were to kill a bird in the presence of a native Australian who had the bird
+for his totem, the black might say, "What for you kill that fellow? that my
+father!" or "That brother belonging to me you have killed; why did you do
+it?"  (E. Palmer, "Notes on some Australian Tribes", "Journal of the
+Anthropological Institute", XIII. (1884), page 300.)  Bechuanas of the
+Porcupine clan are greatly afflicted if anybody hurts or kills a porcupine
+in their presence.  They say, "They have killed our brother, our master,
+one of ourselves, him whom we sing of"; and so saying they piously gather
+the quills of their murdered brother, spit on them, and rub their eyebrows
+with them.  They think they would die if they touched its flesh.  In like
+manner Bechuanas of the Crocodile clan call the crocodile one of
+themselves, their master, their brother; and they mark the ears of their
+cattle with a long slit like a crocodile's mouth by way of a family crest. 
+Similarly Bechuanas of the Lion clan would not, like the members of other
+clans, partake of lion's flesh; for how, say they, could they eat their
+grandfather?  If they are forced in self-defence to kill a lion, they do so
+with great regret and rub their eyes carefully with its skin, fearing to
+lose their sight if they neglected this precaution.  (T. Arbousset et F.
+Daumas, "Relation d'un Voyage d'Exploration au Nord-Est de la Colonie du
+Cap de Bonne-Esperance" (Paris, 1842), pages 349 sq., 422-24.)  A Mandingo
+porter has been known to offer the whole of his month's pay to save the
+life of a python, because the python was his totem and he therefore
+regarded the reptile as his relation; he thought that if he allowed the
+creature to be killed, the whole of his own family would perish, probably
+through the vengeance to be taken by the reptile kinsfolk of the murdered
+serpent.  (M. le Docteur Tautain, "Notes sur les Croyances et Pratiques
+Religieuses des Banmanas", "Revue d'Ethnographie", III. (1885), pages 396
+sq.; A. Rancon, "Dans la Haute-Gambie, Voyage d'Exploration Scientifique"
+(Paris, 1894), page 445.)
+
+Sometimes, indeed, the savage goes further and identifies the revered
+animal not merely with a kinsman but with himself; he imagines that one of
+his own more or less numerous souls, or at all events that a vital part of
+himself, is in the beast, so that if it is killed he must die.  Thus, the
+Balong tribe of the Cameroons, in West Africa, think that every man has
+several souls, of which one is lodged in an elephant, a wild boar, a
+leopard, or what not.  When any one comes home, feels ill, and says, "I
+shall soon die," and is as good as his word, his friends are of opinion
+that one of his souls has been shot by a hunter in a wild boar or a
+leopard, for example, and that that is the real cause of his death.  (J.
+Keller, "Ueber das Land und Volk der Balong", "Deutsches Kolonialblatt", 1
+October, 1895, page 484.)  A Catholic missionary, sleeping in the hut of a
+chief of the Fan negroes, awoke in the middle of the night to see a huge
+black serpent of the most dangerous sort in the act of darting at him.  He
+was about to shoot it when the chief stopped him, saying, "In killing that
+serpent, it is me that you would have killed.  Fear nothing, the serpent is
+my elangela."  (Father Trilles, "Chez les Fang, leurs Moeurs, leur Langue,
+leur Religion", "Les Missions Catholiques", XXX. (1898), page 322.)  At
+Calabar there used to be some years ago a huge old crocodile which was well
+known to contain the spirit of a chief who resided in the flesh at Duke
+Town.  Sporting Vice-Consuls, with a reckless disregard of human life, from
+time to time made determined attempts to injure the animal, and once a
+peculiarly active officer succeeded in hitting it.  The chief was
+immediately laid up with a wound in his leg.  He SAID that a dog had bitten
+him, but few people perhaps were deceived by so flimsy a pretext.  (Miss
+Mary H. Kingsley, "Travels in West Africa" (London, 1897), pages 538 sq. 
+As to the external or bush souls of human beings, which in this part of
+Africa are supposed to be lodged in the bodies of animals, see Miss Mary H.
+Kingsley op. cit. pages 459-461; R. Henshaw, "Notes on the Efik belief in
+'bush soul'", "Man", VI.(1906), pages 121 sq.; J. Parkinson, "Notes on the
+Asaba people (Ibos) of the Niger", "Journal of the Anthropological
+Institute", XXXVI. (1906), pages 314 sq.)  Once when Mr Partridge's canoe-
+men were about to catch fish near an Assiga town in Southern Nigeria, the
+natives of the town objected, saying, "Our souls live in those fish, and if
+you kill them we shall die."  (Charles Partridge, "Cross River Natives"
+(London, 1905), pages 225 sq.)  On another occasion, in the same region, an
+Englishman shot a hippopotamus near a native village.  The same night a
+woman died in the village, and her friends demanded and obtained from the
+marksman five pounds as compensation for the murder of the woman, whose
+soul or second self had been in that hippopotamus.  (C.H. Robinson,
+"Hausaland" (London, 1896), pages 36 sq.)  Similarly at Ndolo, in the Congo
+region, we hear of a chief whose life was bound up with a hippopotamus, but
+he prudently suffered no one to fire at the animal.  ("Notes Analytiques
+sur les Collections Ethnographiques du Musee du Congo", I. (Brussels, 1902-
+06), page 150.
+
+Amongst people who thus fail to perceive any sharp line of distinction
+between beasts and men it is not surprising to meet with the belief that
+human beings are directly descended from animals.  Such a belief is often
+found among totemic tribes who imagine that their ancestors sprang from
+their totemic animals or plants; but it is by no means confined to them. 
+Thus, to take instances, some of the Californian Indians, in whose
+mythology the coyote or prairie-wolf is a leading personage, think that
+they are descended from coyotes.  At first they walked on all fours; then
+they began to have some members of the human body, one finger, one toe, one
+eye, one ear, and so on; then they got two fingers, two toes, two eyes, two
+ears, and so forth; till at last, progressing from period to period, they
+became perfect human beings.  The loss of their tails, which they still
+deplore, was produced by the habit of sitting upright.  (H.R. Schoolcraft,
+"Indian Tribes of the United States", IV. (Philadelphia, 1856), pages 224
+sq.; compare id. V. page 217.  The descent of some, not all, Indians from
+coyotes is mentioned also by Friar Boscana, in (A. Robinson's) "Life in
+California" (New York, 1846), page 299.)  Similarly Darwin thought that
+"the tail has disappeared in man and the anthropomorphous apes, owing to
+the terminal portion having been injured by friction during a long lapse of
+time; the basal and embedded portion having been reduced and modified, so
+as to become suitable to the erect or semi-erect position."  (Charles
+Darwin, "The Descent of Man", Second Edition (London, 1879), page 60.)  The
+Turtle clam of the Iroquois think that they are descended from real mud
+turtles which used to live in a pool.  One hot summer the pool dried up,
+and the mud turtles set out to find another.  A very fat turtle, waddling
+after the rest in the heat, was much incommoded by the weight of his shell,
+till by a great effort he heaved it off altogether.  After that he
+gradually developed into a man and became the progenitor of the Turtle
+clan.  (E.A. Smith, "Myths of the Iroquois", "Second Annual Report of the
+Bureau of Ethnology" (Washington, 1883), page 77.)  The Crawfish band of
+the Choctaws are in like manner descended from real crawfish, which used to
+live under ground, only coming up occasionally through the mud to the
+surface.  Once a party of Choctaws smoked them out, taught them the Choctaw
+language, taught them to walk on two legs, made them cut off their toe
+nails and pluck the hair from their bodies, after which they adopted them
+into the tribe.  But the rest of their kindred, the crawfish, are crawfish
+under ground to this day.  (Geo. Catlin, "North American Indians"4 (London,
+1844), II. page 128.)  The Osage Indians universally believed that they
+were descended from a male snail and a female beaver.  A flood swept the
+snail down to the Missouri and left him high and dry on the bank, where the
+sun ripened him into a man.  He met and married a beaver maid, and from the
+pair the tribe of the Osages is descended.  For a long time these Indians
+retained a pious reverence for their animal ancestors and refrained from
+hunting beavers, because in killing a beaver they killed a brother of the
+Osages.  But when white men came among them and offered high prices for
+beaver skins, the Osages yielded to the temptation and took the lives of
+their furry brethren.  (Lewis and Clarke, "Travels to the Source of the
+Missouri River" (London, 1815), I. 12 (Vol. I. pages 44 sq. of the London
+reprint, 1905).)  The Carp clan of the Ootawak Indians are descended from
+the eggs of a carp which had been deposited by the fish on the banks of a
+stream and warmed by the sun.  ("Lettres Edifiantes et Curieuses", Nouvelle
+Edition, VI. (Paris, 1781), page 171.)  The Crane clan of the Ojibways are
+sprung originally from a pair of cranes, which after long wanderings
+settled on the rapids at the outlet of Lake Superior, where they were
+changed by the Great Spirit into a man and woman.  (L.H. Morgan, "Ancient
+Society" (London, 1877), page 180.)  The members of two Omaha clans were
+originally buffaloes and lived, oddly enough, under water, which they
+splashed about, making it muddy.  And at death all the members of these
+clans went back to their ancestors the buffaloes.  So when one of them lay
+adying, his friends used to wrap him up in a buffalo skin with the hair
+outside and say to him, "You came hither from the animals and you are going
+back thither.  Do not face this way again.  When you go, continue walking. 
+(J. Owen Dorsey, "Omaha Sociology", "Third Annual Report of the Bureau of
+Ethnology" (Washington, 1884), pages 229, 233.)  The Haida Indians of Queen
+Charlotte Islands believe that long ago the raven, who is the chief figure
+in the mythology of North-West America, took a cockle from the beach and
+married it; the cockle gave birth to a female child, whom the raven took to
+wife, and from their union the Indians were produced.  (G.M. Dawson,
+"Report on the Queen Charlotte Islands" (Montreal, 1880), pages 149B sq. 
+("Geological Survey of Canada"); F. Poole, "Queen Charlotte Islands", page
+136.)  The Delaware Indians called the rattle-snake their grandfather and
+would on no account destroy one of these reptiles, believing that were they
+to do so the whole race of rattle-snakes would rise up and bite them. 
+Under the influence of the white man, however, their respect for their
+grandfather the rattle-snake gradually died away, till at last they killed
+him without compunction or ceremony whenever they met him.  The writer who
+records the old custom observes that he had often reflected on the curious
+connection which appears to subsist in the mind of an Indian between man
+and the brute creation; "all animated nature," says he, "in whatever
+degree, is in their eyes a great whole, from which they have not yet
+ventured to separate themselves."  (Rev. John Heckewelder, "An Account of
+the History, Manners, and Customs, of the Indian Nations, who once
+inhabited Pennsylvania and the Neighbouring States", "Transactions of the
+Historical and Literary Committee of the American Philosophical Society",
+I. (Philadelphia, 1819), pages 245, 247, 248.)
+
+Some of the Indians of Peru boasted of being descended from the puma or
+American lion; hence they adored the lion as a god and appeared at
+festivals like Hercules dressed in the skins of lions with the heads of the
+beasts fixed over their own.  Others claimed to be sprung from condors and
+attired themselves in great black and white wings, like that enormous bird. 
+(Garcilasso de la Vega, "First Part of the Royal Commentaries of the
+Yncas", Vol. I. page 323, Vol. II. page 156 (Markham's translation).)  The
+Wanika of East Africa look upon the hyaena as one of their ancestors or as
+associated in some way with their origin and destiny.  The death of a
+hyaena is mourned by the whole people, and the greatest funeral ceremonies
+which they perform are performed for this brute.  The wake held over a
+chief is as nothing compared to the wake held over a hyaena; one tribe only
+mourns the death of its chief, but all the tribes unite to celebrate the
+obsequies of a hyaena.  (Charles New, "Life, Wanderings, and Labours in
+Eastern Africa" (London, 1873) page 122.)  Some Malagasy families claim to
+be descended from the babacoote (Lichanotus brevicaudatus), a large lemur
+of grave appearance and staid demeanour, which lives in the depth of the
+forest.  When they find one of these creatures dead, his human descendants
+bury it solemnly, digging a grave for it, wrapping it in a shroud, and
+weeping and lamenting over its carcase.  A doctor who had shot a babacoote
+was accused by the inhabitants of a Betsimisaraka village of having killed
+"one of their grandfathers in the forest," and to appease their indignation
+he had to promise not to skin the animal in the village but in a solitary
+place where nobody could see him.  (Father Abinal, "Croyances fabuleuses
+des Malgaches", "Les Missions Catholiques", XII. (1880), page 526; G.H.
+Smith, "Some Betsimisaraka superstitions", "The Antananarivo Annual and
+Madagascar Magazine", No. 10 (Antananarivo, 1886), page 239; H.W. Little,
+"Madagascar, its History and People" (London, 1884), pages 321 sq; A. van
+Gennep, "Tabou et Totemisme a Madagascar" (Paris, 1904), pages 214 sqq.) 
+Many of the Betsimisaraka believe that the curious nocturnal animal called
+the aye-aye (Cheiromys madagascariensis) "is the embodiment of their
+forefathers, and hence will not touch it, much less do it an injury.  It is
+said that when one is discovered dead in the forest, these people make a
+tomb for it and bury it with all the forms of a funeral.  They think that
+if they attempt to entrap it, they will surely die in consequence."  (G.A.
+Shaw, "The Aye-aye", "Antananarivo Annual and Madagascar Magazine", Vol.
+II. (Antananarivo, 1896), pages 201, 203 (Reprint of the Second four
+Numbers).  Compare A. van Gennep, "Tabou et Totemisme a Madagascar", pages
+223 sq.)  Some Malagasy tribes believe themselves descended from crocodiles
+and accordingly they deem the formidable reptiles their brothers.  If one
+of these scaly brothers so far forgets the ties of kinship as to devour a
+man, the chief of the tribe, or in his absence an old man familiar with the
+tribal customs, repairs at the head of the people to the edge of the water,
+and summons the family of the culprit to deliver him up to the arm of
+justice.  A hook is then baited and cast into the river or lake.  Next day
+the guilty brother or one of his family is dragged ashore, formally tried,
+sentenced to death, and executed.  The claims of justice being thus
+satisfied, the dead animal is lamented and buried like a kinsman; a mound
+is raised over his grave and a stone marks the place of his head.  (Father
+Abinal, "Croyances fabuleuses des Malgaches", "Les Missions Catholiques",
+XII. (1880), page 527; A. van Gennep, "Tabou et Totemisme a Madagascar",
+pages 281 sq.)
+
+Amongst the Tshi-speaking tribes of the Gold Coast in West Africa the
+Horse-mackerel family traces its descent from a real horse-mackerel whom an
+ancestor of theirs once took to wife.  She lived with him happily in human
+shape on shore till one day a second wife, whom the man had married,
+cruelly taunted her with being nothing but a fish.  That hurt her so much
+that bidding her husband farewell she returned to her old home in the sea,
+with her youngest child in her arms, and never came back again.  But ever
+since the Horse-mackerel people have refrained from eating horse-mackerels,
+because the lost wife and mother was a fish of that sort.  (A.B. Ellis,
+"The Tshi-speaking Peoples of the Gold Coast of West Africa" (London,
+1887), pages 208-11.  A similar tale is told by another fish family who
+abstain from eating the fish (appei) from which they take their name (A.B.
+Ellis op. cit. pages 211 sq.).)  Some of the Land Dyaks of Borneo tell a
+similar tale to explain a similar custom.  "There is a fish which is taken
+in their rivers called a puttin, which they would on no account touch,
+under the idea that if they did they would be eating their relations.  The
+tradition respecting it is, that a solitary old man went out fishing and
+caught a puttin, which he dragged out of the water and laid down in his
+boat.  On turning round, he found it had changed into a very pretty little
+girl.  Conceiving the idea she would make, what he had long wished for, a
+charming wife for his son, he took her home and educated her until she was
+fit to be married.  She consented to be the son's wife cautioning her
+husband to use her well.  Some time after their marriage, however, being
+out of temper, he struck her, when she screamed, and rushed away into the
+water; but not without leaving behind her a beautiful daughter, who became
+afterwards the mother of the race."  (The Lord Bishop of Labuan, "On the
+Wild Tribes of the North-West Coast of Borneo", "Transactions of the
+Ethnological Society of London", New Series II. (London, 1863), pages 26
+sq.  Such stories conform to a well-known type which may be called the
+Swan-Maiden type of story, or Beauty and the Beast, or Cupid and Psyche. 
+The occurrence of stories of this type among totemic peoples, such as the
+Tshi-speaking negroes of the Gold Coast, who tell them to explain their
+totemic taboos, suggests that all such tales may have originated in
+totemism.  I shall deal with this question elsewhere.)
+
+Members of a clan in Mandailing, on the west coast of Sumatra, assert that
+they are descended from a tiger, and at the present day, when a tiger is
+shot, the women of the clan are bound to offer betel to the dead beast. 
+When members of this clan come upon the tracks of a tiger, they must, as a
+mark of homage, enclose them with three little sticks.  Further, it is
+believed that the tiger will not attack or lacerate his kinsmen, the
+members of the clan.  (H. Ris, "De Onderafdeeling Klein Mandailing Oeloe en
+Pahantan en hare Bevolking met uitzondering van de Oeloes", "Bijdragen tot
+de Tall- Land- en Volkenkunde van Nederlansch-Indie, XLVI. (1896), page
+473.)  The Battas of Central Sumatra are divided into a number of clans
+which have for their totems white buffaloes, goats, wild turtle-doves,
+dogs, cats, apes, tigers, and so forth; and one of the explanations which
+they give of their totems is that these creatures were their ancestors, and
+that their own souls after death can transmigrate into the animals.  (J.B.
+Neumann, "Het Pane en Bila-stroomgebied op het eiland Sumatra",
+"Tijdschrift van het Nederlandsch Aardrijkskundig Genootschap", Tweede
+Serie, III. Afdeeling, Meer uitgebreide Artikelen, No. 2 (Amsterdam, 1886),
+pages 311 sq.; id. ib. Tweede Serie, IV. Afdeeling, Meer uitgebreide
+Artikelen, No. 1 (Amsterdam, 1887), pages 8 sq.)  In Amboyna and the
+neighbouring islands the inhabitants of some villages aver that they are
+descended from trees, such as the Capellenia moluccana, which had been
+fertilised by the Pandion Haliaetus.  Others claim to be sprung from pigs,
+octopuses, crocodiles, sharks, and eels.  People will not burn the wood of
+the trees from which they trace their descent, nor eat the flesh of the
+animals which they regard as their ancestors.  Sicknesses of all sorts are
+believed to result from disregarding these taboos.  (J.G.F. Riedel, "De
+sluik- en kroesharige rassen tusschen Selebes en Papua" (The Hague, 1886),
+pages 32, 61; G.W.W.C. Baron van Hoevell, "Ambon en meer bepaaldelijk de
+Oeliasers" (Dordrecht, 1875), page 152.)  Similarly in Ceram persons who
+think they are descended from crocodiles, serpents, iguanas, and sharks
+will not eat the flesh of these animals.  (J.G.F. Riedel op. cit. page
+122.)  Many other peoples of the Molucca Islands entertain similar beliefs
+and observe similar taboos.  (J.G.F. Riedel "De sluik- en kroesharige
+rassen tusschen Selebes en Papua" (The Hague, 1886), pages 253, 334, 341,
+348, 412, 414, 432.)  Again, in Ponape, one of the Caroline Islands, "The
+different families suppose themselves to stand in a certain relation to
+animals, and especially to fishes, and believe in their descent from them. 
+They actually name these animals 'mothers'; the creatures are sacred to the
+family and may not be injured.  Great dances, accompanied with the offering
+of prayers, are performed in their honour.  Any person who killed such an
+animal would expose himself to contempt and punishment, certainly also to
+the vengeance of the insulted deity."  Blindness is commonly supposed to be
+the consequence of such a sacrilege.  (Dr Hahl, "Mittheilungen uber Sitten
+und rechtliche Verhaltnisse auf Ponape", "Ethnologisches Notizblatt", Vol.
+II. Heft 2 (Berlin, 1901), page 10.)
+
+Some of the aborigines of Western Australia believe that their ancestors
+were swans, ducks, or various other species of water-fowl before they were
+transformed into men.  (Captain G. Grey, "A Vocabulary of the Dialects of
+South Western Australia", Second Edition (London, 1840), pages 29, 37, 61,
+63, 66, 71.)  The Dieri tribe of Central Australia, who are divided into
+totemic clans, explain their origin by the following legend.  They say that
+in the beginning the earth opened in the midst of Perigundi Lake, and the
+totems (murdus or madas) came trooping out one after the other.  Out came
+the crow, and the shell parakeet, and the emu, and all the rest.  Being as
+yet imperfectly formed and without members or organs of sense, they laid
+themselves down on the sandhills which surrounded the lake then just as
+they do now.  It was a bright day and the totems lay basking in the
+sunshine, till at last, refreshed and invigorated by it, they stood up as
+human beings and dispersed in all directions.  That is why people of the
+same totem are now scattered all over the country.  You may still see the
+island in the lake out of which the totems came trooping long ago.  (A.W.
+Howitt, "Native Tribes of South-East Australia" (London, 1904), pages 476,
+779 sq.)  Another Dieri legend relates how Paralina, one of the Mura-Muras
+or mythical predecessors of the Dieri, perfected mankind.  He was out
+hunting kangaroos, when he saw four incomplete beings cowering together. 
+So he went up to them, smoothed their bodies, stretched out their limbs,
+slit up their fingers and toes, formed their mouths, noses, and eyes, stuck
+ears on them, and blew into their ears in order that they might hear. 
+Having perfected their organs and so produced mankind out of these
+rudimentary beings, he went about making men everywhere.  (A.W. Howitt op.
+cit., pages 476, 780 sq.)  Yet another Dieri tradition sets forth how the
+Mura-Mura produced the race of man out of a species of small black lizards,
+which may still be met with under dry bark.  To do this he divided the feet
+of the lizards into fingers and toes, and, applying his forefinger to the
+middle of their faces, created a nose; likewise he gave them human eyes,
+mouths and ears.  He next set one of them upright, but it fell down again
+because of its tail; so he cut off its tail and the lizard then walked on
+its hind legs.  That is the origin of mankind.  (S. Gason, "The Manners and
+Customs of the Dieyerie tribe of Australian Aborigines", "Native Tribes of
+South Australia" (Adelaide, 1879), page 260.  This writer fell into the
+mistake of regarding the Mura-Mura (Mooramoora) as a Good-Spirit instead of
+as one of the mythical but more or less human predecessors of the Dieri in
+the country.  See A.W. Howitt, "Native Tribes of South-East Australia",
+pages 475 sqq.)
+
+The Arunta tribe of Central Australia similarly tell how in the beginning
+mankind was developed out of various rudimentary forms of animal life. 
+They say that in those days two beings called Ungambikula, that is, "out of
+nothing," or "self-existing," dwelt in the western sky.  From their lofty
+abode they could see, far away to the east, a number of inapertwa
+creatures, that is, rudimentary human beings or incomplete men, whom it was
+their mission to make into real men and women.  For at that time there were
+no real men and women; the rudimentary creatures (inapertwa) were of
+various shapes and dwelt in groups along the shore of the salt water which
+covered the country.  These embryos, as we may call them, had no distinct
+limbs or organs of sight, hearing, and smell; they did not eat food, and
+they presented the appearance of human beings all doubled up into a rounded
+mass, in which only the outline of the different parts of the body could be
+vaguely perceived.  Coming down from their home in the western sky, armed
+with great stone knives, the Ungambikula took hold of the embryos, one
+after the other.  First of all they released the arms from the bodies, then
+making four clefts at the end of each arm they fashioned hands and fingers;
+afterwards legs, feet, and toes were added in the same way.  The figure
+could now stand; a nose was then moulded and the nostrils bored with the
+fingers.  A cut with the knife made the mouth, which was pulled open
+several times to render it flexible.  A slit on each side of the face
+separated the upper and lower eye-lids, disclosing the eyes, which already
+existed behind them; and a few strokes more completed the body.  Thus out
+of the rudimentary creatures were formed men and women.  These rudimentary
+creatures or embryos, we are told, "were in reality stages in the
+transformation of various animals and plants into human beings, and thus
+they were naturally, when made into human beings, intimately associated
+with the particular animal or plant, as the case may be, of which they were
+the transformations--in other words, each individual of necessity belonged
+to a totem, the name of which was of course that of the animal or plant of
+which he or she was a transformation."  However, it is not said that all
+the totemic clans of the Arunta were thus developed; no such tradition, for
+example, is told to explain the origin of the important Witchetty Grub
+clan.  The clans which are positively known, or at least said, to have
+originated out of embryos in the way described are the Plum Tree, the Grass
+Seed, the Large Lizard, the Small Lizard, the Alexandra Parakeet, and the
+Small Rat clans.  When the Ungambikula had thus fashioned people of these
+totems, they circumcised them all, except the Plum Tree men, by means of a
+fire-stick.  After that, having done the work of creation or evolution, the
+Ungambikula turned themselves into little lizards which bear a name meaning
+"snappers-up of flies."  (Baldwin Spencer and F.J. Gillen, "Native Tribes
+of Central Australia (London, 1899), pages 388 sq.; compare id., "Northern
+Tribes of Central Australia" (London, 1904), page 150.)
+
+This Arunta tradition of the origin of man, as Messrs Spencer and Gillen,
+who have recorded it, justly observe, "is of considerable interest; it is
+in the first place evidently a crude attempt to describe the origin of
+human beings out of non-human creatures who were of various forms; some of
+them were representatives of animals, others of plants, but in all cases
+they are to be regarded as intermediate stages in the transition of an
+animal or plant ancestor into a human individual who bore its name as that
+of his or her totem."  (Baldwin Spencer and F.J. Gillen, "Native Tribes of
+Central Australia", pages 391 sq.)  In a sense these speculations of the
+Arunta on their own origin may be said to combine the theory of creation
+with the theory of evolution; for while they represent men as developed out
+of much simpler forms of life, they at the same time assume that this
+development was effected by the agency of two powerful beings, whom so far
+we may call creators.  It is well known that at a far higher stage of
+culture a crude form of the evolutionary hypothesis was propounded by the
+Greek philosopher Empedocles.  He imagined that shapeless lumps of earth
+and water, thrown up by the subterranean fires, developed into monstrous
+animals, bulls with the heads of men, men with the heads of bulls, and so
+forth; till at last, these hybrid forms being gradually eliminated, the
+various existing species of animals and men were evolved.  (E. Zeller, "Die
+Philosophie der Griechen", I.4 (Leipsic, 1876), pages 718 sq.; H. Ritter et
+L. Preller, "Historia Philosophiae Graecae et Romanae ex fontium locis
+contexta"5, pages 102 sq.  H. Diels, "Die Fragmente der Vorsokratiker"2, I.
+(Berlin, 1906), pages 190 sqq.  Compare Lucretius "De rerum natura", V. 837
+sqq.)  The theory of the civilised Greek of Sicily may be set beside the
+similar theory of the savage Arunta of Central Australia.  Both represent
+gropings of the human mind in the dark abyss of the past; both were in a
+measure grotesque anticipations of the modern theory of evolution.
+
+In this essay I have made no attempt to illustrate all the many various and
+divergent views which primitive man has taken of his own origin.  I have
+confined myself to collecting examples of two radically different views,
+which may be distinguished as the theory of creation and the theory of
+evolution.  According to the one, man was fashioned in his existing shape
+by a god or other powerful being; according to the other he was evolved by
+a natural process out of lower forms of animal life.  Roughly speaking,
+these two theories still divide the civilised world between them.  The
+partisans of each can appeal in support of their view to a large consensus
+of opinion; and if truth were to be decided by weighing the one consensus
+against the other, with "Genesis" in the one scale and "The Origin of
+Species" in the other, it might perhaps be found, when the scales were
+finally trimmed, that the balance hung very even between creation and
+evolution.
+
+
+X.  THE INFLUENCE OF DARWIN ON THE STUDY OF ANIMAL EMBRYOLOGY.
+
+By A. SEDGWICK, M.A., F.R.S.
+Professor of Zoology and Comparative Anatomy in the University of
+Cambridge.
+
+The publication of "The Origin of Species" ushered in a new era in the
+study of Embryology.  Whereas, before the year 1859 the facts of anatomy
+and development were loosely held together by the theory of types, which
+owed its origin to the great anatomists of the preceding generation, to
+Cuvier, L. Agassiz, J. Muller, and R. Owen, they were now combined together
+into one organic whole by the theory of descent and by the hypothesis of
+recapitulation which was deduced from that theory.  The view (First clearly
+enunciated by Fritz Muller in his well-known work, "Fur Darwin", Leipzig,
+1864; (English Edition, "Facts for Darwin", 1869).) that a knowledge of
+embryonic and larval histories would lay bare the secrets of race-history
+and enable the course of evolution to be traced, and so lead to the
+discovery of the natural system of classification, gave a powerful stimulus
+to morphological study in general and to embryological investigation in
+particular.  In Darwin's words:  "Embryology rises greatly in interest,
+when we look at the embryo as a picture, more or less obscured, of the
+progenitor, either in its adult or larval state, of all the members of the
+same great class."  ("Origin" (6th edition), page 396.)  In the period
+under consideration the output of embryological work has been enormous.  No
+group of the animal kingdom has escaped exhaustive examination and no
+effort has been spared to obtain the embryos of isolated and out of the way
+forms, the development of which might have an important bearing upon
+questions of phylogeny and classification.  Marine zoological stations have
+been established, expeditions have been sent to distant countries, and the
+methods of investigation have been greatly improved.  The result of this
+activity has been that the main features of the developmental history of
+all the most important animals are now known and the curiosity as to
+developmental processes, so greatly excited by the promulgation of the
+Darwinian theory, has to a considerable extent been satisfied.
+
+To what extent have the results of this vast activity fulfilled the
+expectations of the workers who have achieved them?  The Darwin centenary
+is a fitting moment at which to take stock of our position.  In this
+inquiry we shall leave out of consideration the immense and intensely
+interesting additions to our knowledge of Natural History.  These may be
+said to constitute a capital fund upon which philosophers, poets and men of
+science will draw for many generations.  The interest of Natural History
+existed long before Darwinian evolution was thought of and will endure
+without any reference to philosophic speculations.  She is a mistress in
+whose face are beauties and in whose arms are delights elsewhere
+unattainable.  She is and always has been pursued for her own sake without
+any reference to philosophy, science, or utility.
+
+Darwin's own views of the bearing of the facts of embryology upon questions
+of wide scientific interest are perfectly clear.  He writes ("Origin" (6th
+edition), page 395.):
+
+"On the other hand it is highly probable that with many animals the
+embryonic or larval stages show us, more or less completely, the condition
+of the progenitor of the whole group in its adult state.  In the great
+class of the Crustacea, forms wonderfully distinct from each other, namely,
+suctorial parasites, cirripedes, entomostraca, and even the malacostraca,
+appear at first as larvae under the nauplius-form; and as these larvae live
+and feed in the open sea, and are not adapted for any peculiar habits of
+life, and from other reasons assigned by Fritz Muller, it is probable that
+at some very remote period an independent adult animal, resembling the
+Nauplius, existed, and subsequently produced, along several divergent lines
+of descent, the above-named great Crustacean groups.  So again it is
+probable, from what we know of the embryos of mammals, birds, fishes, and
+reptiles, that these animals are the modified descendants of some ancient
+progenitor, which was furnished in its adult state with branchiae, a swim-
+bladder, four fin-like limbs, and a long tail, all fitted for an aquatic
+life.
+
+"As all the organic beings, extinct and recent, which have ever lived, can
+be arranged within a few great classes; and as all within each class have,
+according to our theory, been connected together by fine gradations, the
+best, and, if our collections were nearly perfect, the only possible
+arrangement, would be genealogical; descent being the hidden bond of
+connexion which naturalists have been seeking under the term of the Natural
+System.  On this view we can understand how it is that, in the eyes of most
+naturalists, the structure of the embryo is even more important for
+classification than that of the adult.  In two or more groups of animals,
+however much they may differ from each other in structure and habits in
+their adult condition, if they pass through closely similar embryonic
+stages, we may feel assured that they all are descended from one parent-
+form, and are therefore closely related.  Thus, community in embryonic
+structure reveals community of descent; but dissimilarity in embryonic
+development does not prove discommunity of descent, for in one of two
+groups the developmental stages may have been suppressed, or may have been
+so greatly modified through adaptation to new habits of life, as to be no
+longer recognisable.  Even in groups, in which the adults have been
+modified to an extreme degree, community of origin is often revealed by the
+structure of the larvae; we have seen, for instance, that cirripedes,
+though externally so like shell-fish, are at once known by their larvae to
+belong to the great class of crustaceans.  As the embryo often shows us
+more or less plainly the structure of the less modified and ancient
+progenitor of the group, we can see why ancient and extinct forms so often
+resemble in their adult state the embryos of existing species of the same
+class.  Agassiz believes this to be a universal law of nature; and we may
+hope hereafter to see the law proved true.  It can, however, be proved true
+only in those cases in which the ancient state of the progenitor of the
+group has not been wholly obliterated, either by successive variations
+having supervened at a very early period of growth, or by such variations
+having been inherited at an earlier stage than that at which they first
+appeared.  It should also be borne in mind, that the law may be true, but
+yet, owing to the geological record not extending far enough back in time,
+may remain for a long period, or for ever, incapable of demonstration.  The
+law will not strictly hold good in those cases in which an ancient form
+became adapted in its larval state to some special line of life, and
+transmitted the same larval state to a whole group of descendants; for such
+larvae will not resemble any still more ancient form in its adult state."
+
+As this passage shows, Darwin held that embryology was of interest because
+of the light it seems to throw upon ancestral history (phylogeny) and
+because of the help it would give in enabling us to arrive at a natural
+system of classification.  With regard to the latter point, he quotes with
+approval the opinion that "the structure of the embryo is even more
+important for classification than that of the adult."  What justification
+is there for this view?  The phase of life chosen for the ordinary
+anatomical and physiological studies, namely, the adult phase, is merely
+one of the large number of stages of structure through which the organism
+passes.  By far the greater number of these are included in what is
+specially called the developmental or (if we include larvae with embryos)
+embryonic period, for the developmental changes are more numerous and take
+place with greater rapidity at the beginning of life than in its later
+periods.  As each of these stages is equal in value, for our present
+purpose, to the adult phase, it clearly follows that if there is anything
+in the view that the anatomical study of organisms is of importance in
+determining their mutual relations, the study of the organism in its
+various embryonic (and larval) stages must have a greater importance than
+the study of the single and arbitrarily selected stage of life called the
+adult.
+
+But a deeper reason than this has been assigned for the importance of
+embryology in classification.  It has been asserted, and is implied by
+Darwin in the passage quoted, that the ancestral history is repeated in a
+condensed form in the embryonic, and that a study of the latter enables us
+to form a picture of the stages of structure through which the organism has
+passed in its evolution.  It enables us on this view to reconstruct the
+pedigrees of animals and so to form a genealogical tree which shall be the
+true expression of their natural relations.
+
+The real question which we have to consider is to what extent the
+embryological studies of the last 50 years have confirmed or rendered
+probable this "theory of recapitulation."  In the first place it must be
+noted that the recapitulation theory is itself a deduction from the theory
+of evolution.  The facts of embryology, particularly of vertebrate
+embryology, and of larval history receive, it is argued, an explanation on
+the view that the successive stages of development are, on the whole,
+records of adult stages of structure which the species has passed through
+in its evolution.  Whether this statement will bear a critical verbal
+examination I will not now pause to inquire, for it is more important to
+determine whether any independent facts can be alleged in favour of the
+theory.  If it could be shown, as was stated to be the case by L. Agassiz,
+that ancient and extinct forms of life present features of structure now
+only found in embryos, we should have a body of facts of the greatest
+importance in the present discussion.  But as Huxley (See Huxley's
+"Scientific Memoirs", London, 1898, Vol. I. page 303:  "There is no real
+parallel between the successive forms assumed in the development of the
+life of the individual at present, and those which have appeared at
+different epochs in the past."  See also his Address to the Geological
+Society of London (1862) 'On the Palaeontological Evidence of Evolution',
+ibid. Vol. II. page 512.) has shown and as the whole course of
+palaeontological and embryological investigation has demonstrated, no such
+statement can be made.  The extinct forms of life are very similar to those
+now existing and there is nothing specially embryonic about them.  So that
+the facts, as we know them, lend no support to theory.
+
+But there is another class of facts which have been alleged in favour of
+the theory, viz. the facts which have been included in the generalisation
+known as the Law of v. Baer.  The law asserts that embryos of different
+species of animals of the same group are more alike than the adults and
+that, the younger the embryo, the greater are the resemblances.  If this
+law could be established it would undoubtedly be a strong argument in
+favour of the "recapitulation" explanation of the facts of embryology.  But
+its truth has been seriously disputed.  If it were true we should expect to
+find that the embryos of closely similar species would be indistinguishable
+from one another, but this is notoriously not the case.  It is more
+difficult to meet the assertion when it is made in the form given above,
+for here we are dealing with matters of opinion.  For instance, no one
+would deny that the embryo of a dogfish is different from the embryo of a
+rabbit, but there is room for difference of opinion when it is asserted
+that the difference is less than the difference between an adult dogfish
+and an adult rabbit.  It would be perfectly true to say that the
+differences between the embryos concern other organs more than do the
+differences between the adults, but who is prepared to affirm that the
+presence of a cephalic coelom and of cranial segments, of external gills,
+of six gill slits, of the kidney tubes opening into the muscle-plate
+coelom, of an enormous yolk-sac, of a neurenteric canal, and the absence of
+any trace of an amnion, of an allantois and of a primitive streak are not
+morphological facts of as high an import as those implied by the
+differences between the adults?  The generalisation undoubtedly had its
+origin in the fact that there is what may be called a family resemblance
+between embryos and larvae, but this resemblance, which is by no means
+exact, is largely superficial and does not extend to anatomical detail.
+
+It is useless to say, as Weismann has stated ("The Evolution Theory", by A.
+Weismann, English Translation, Vol. II. page 176, London, 1904.), that "it
+cannot be disputed that the rudiments [vestiges his translator means] of
+gill-arches and gill-clefts, which are peculiar to one stage of human
+ontogeny, give us every ground for concluding that we possessed fish-like
+ancestors."  The question at issue is:  did the pharyngeal arches and
+clefts of mammalian embryos ever discharge a branchial function in an adult
+ancestor of the mammalia?  We cannot therefore, without begging the
+question at issue in the grossest manner, apply to them the terms "gill-
+arches" and "gill-clefts".  That they are homologous with the "gill-arches"
+and "gill-clefts" of fishes is true; but there is no evidence to show that
+they ever discharged a branchial function.  Until such evidence is
+forthcoming, it is beside the point to say that it "cannot be disputed"
+that they are evidence of a piscine ancestry.
+
+It must, therefore, be admitted that one outcome of the progress of
+embryological and palaeontological research for the last 50 years is
+negative.  The recapitulation theory originated as a deduction from the
+evolution theory and as a deduction it still remains.
+
+Let us before leaving the subject apply another test.  If the evolution
+theory and the recapitulation theory are both true, how is it that living
+birds are not only without teeth but have no rudiments of teeth at any
+stage of their existence?  How is it that the missing digits in birds and
+mammals, the missing or reduced limb of snakes and whales, the reduced
+mandibulo-hyoid cleft of elasmobranch fishes are not present or relatively
+more highly developed in the embryo than in the adult?  How is it that when
+a marked variation, such as an extra digit, or a reduced limb, or an extra
+segment, makes its appearance, it is not confined to the adult but can be
+seen all through the development?  All the clear evidence we can get tends
+to show that marked variations, whether of reduction or increase, of organs
+are manifest during the whole of the development of the organ and do not
+merely affect the adult.  And on reflection we see that it could hardly be
+otherwise.  All such evidence is distinctly at variance with the theory of
+recapitulation, at least as applied to embryos.  In the case of larvae of
+course the case will be different, for in them the organs are functional,
+and reduction in the adult will not be accompanied by reduction in the
+larva unless a change in the conditions of life of the larva enables it to
+occur.
+
+If after 50 years of research and close examination of the facts of
+embryology the recapitulation theory is still without satisfactory proof,
+it seems desirable to take a wider sweep and to inquire whether the facts
+of embryology cannot be included in a larger category.
+
+As has been pointed out by Huxley, development and life are co-extensive,
+and it is impossible to point to any period in the life of an organism when
+the developmental changes cease.  It is true that these changes take place
+more rapidly at the commencement of life, but they are never wholly absent,
+and those which occur in the later or so-called adult stages of life do not
+differ in their essence, however much they may differ in their degree, from
+those which occur during the embryonic and larval periods.  This
+consideration at once brings the changes of the embryonic period into the
+same category as those of the adult and suggests that an explanation which
+will account for the one will account for the other.  What then is the
+problem we are dealing with?  Surely it is this:  Why does an organism as
+soon as it is established at the fertilisation of the ovum enter upon a
+cycle of transformations which never cease until death puts an end to them?
+In other words what is the meaning of that cycle of changes which all
+organisms present in a greater or less degree and which constitute the very
+essence of life?  It is impossible to give an answer to this question so
+long as we remain within the precincts of Biology--and it is not my present
+purpose to penetrate beyond those precincts into the realms of philosophy.
+We have to do with an ultimate biological fact, with a fundamental property
+of living matter, which governs and includes all its other properties.  How
+may this property be stated?  Thus:  it is a property of living matter to
+react in a remarkable way to external forces without undergoing
+destruction.  The life-cycle, of which the embryonic and larval periods are
+a part, consists of the orderly interaction between the organism and its
+environment.  The action of the environment produces certain morphological
+changes in the organism.  These changes enable the organism to come into
+relation with new external forces, to move into what is practically a new
+environment, which in its turn produces further structural changes in the
+organism.  These in their turn enable, indeed necessitate, the organism to
+move again into a new environment, and so the process continues until the
+structural changes are of such a nature that the organism is unable to
+adapt itself to the environment in which it finds itself.  The essential
+condition of success in this process is that the organism should always
+shift into the environment to which its new structure is suited--any
+failure in this leading to the impairment of the organism.  In most cases
+the shifting of the environment is a very gradual process (whether
+consisting in the very slight and gradual alteration in the relation of the
+embryo as a whole to the egg-shell or uterine wall, or in the relations of
+its parts to each other, or in the successive phases of adult life), and
+the morphological changes in connection with each step of it are but
+slight.  But in some cases jumps are made such as we find in the phenomena
+known as hatching, birth, and metamorphosis.
+
+This property of reacting to the environment without undergoing destruction
+is, as has been stated, a fundamental property of organisms.  It is
+impossible to conceive of any matter, to which the term living could be
+applied, being without it.  And with this property of reacting to the
+environment goes the further property of undergoing a change which alters
+the relation of the organism to the old environment and places it in a new
+environment.  If this reasoning is correct, it necessarily follows that
+this property must have been possessed by living matter at its first
+appearance on the earth.  In other words living matter must always have
+presented a life-cycle, and the question arises what kind of modification
+has that cycle undergone?  Has it increased or diminished in duration and
+complexity since organisms first appeared on the earth?  The current view
+is that the cycle was at first very short and that it has increased in
+length by the evolutionary creation of new adult phases, that these new
+phases are in addition to those already existing and that each of them as
+it appears takes over from the preceding adult phase the functional
+condition of the reproductive organs.  According to the same view the old
+adult phases are not obliterated but persist in a more or less modified
+form as larval stages.  It is further supposed that as the life-history
+lengthens at one end by the addition of new adult phases, it is shortened
+at the other by the abbreviation of embryonic development and by the
+absorption of some of the early larval stages into the embryonic period;
+but on the whole the lengthening process has exceeded that of shortening,
+so that the whole life-history has, with the progress of evolution, become
+longer and more complicated.
+
+Now there can be no doubt that the life-history of organisms has been
+shortened in the way above suggested, for cases are known in which this can
+practically be seen to occur at the present day.  But the process of
+lengthening by the creation of new stages at the other end of the life-
+cycle is more difficult to conceive and moreover there is no evidence for
+its having occurred.  This, indeed, may have occurred, as is suggested
+below, but the evidence we have seems to indicate that evolutionary
+modification has proceeded by ALTERING and not by SUPERSEDING:  that is to
+say that each stage in the life-history, as we see it to-day, has proceeded
+from a corresponding stage in a former era by the modification of that
+stage and not by the creation of a new one.  Let me, at the risk of
+repetition, explain my meaning more fully by taking a concrete
+illustration.  The mandibulo-hyoid cleft (spiracle) of the elasmobranch
+fishes, the lateral digits of the pig's foot, the hind-limbs of whales, the
+enlarged digit of the ostrich's foot are supposed to be organs which have
+been recently modified.  This modification is not confined to the final
+adult stage of the life-history but characterises them throughout the whole
+of their development.  A stage with a reduced spiracle does not proceed in
+development from a preceding stage in which the spiracle shows no
+reduction:  it is reduced at its first appearance.  The same statement may
+be made of organs which have entirely disappeared in the adult, such as
+bird's teeth and snake's fore-limbs:  the adult stage in which they have
+disappeared is not preceded by embryonic stages in which the teeth and
+limbs or rudiments of them are present.  In fact the evidence indicates
+that adult variations of any part are accompanied by precedent variations
+in the same direction in the embryo.  The evidence seems to show, not that
+a stage is added on at the end of the life-history, but only that some of
+the stages in the life-history are modified.  Indeed, on the wider view of
+development taken in this essay, a view which makes it coincident with
+life, one would not expect often to find, even if new stages are added in
+the course of evolution, that they are added at the end of the series when
+the organism has passed through its reproductive period.  It is possible of
+course that new stages have been intercalated in the course of the life-
+history, though it is difficult to see how this has occurred.  It is much
+more likely, if we may judge from available evidence, that every stage has
+had its counterpart in the ancestral form from which it has been derived by
+descent with modification.  Just as the adult phase of the living form
+differs, owing to evolutionary modification, from the adult phase of the
+ancestor from which it has proceeded, so each larval phase will differ for
+the same reason from the corresponding larval phase in the life-history of
+the ancestor.  Inasmuch as the organism is variable at every stage of its
+independent existence and is exposed to the action of natural selection
+there is no reason why it should escape modification at any stage.
+
+If there is any truth in these considerations it would seem to follow that
+at the dawn of life the life-cycle must have been, either in posse or in
+esse, at least as long as it is at the present time, and that the
+peculiarity of passing through a series of stages in which new characters
+are successively evolved is a primordial quality of living matter.
+
+Before leaving this part of the subject, it is necessary to touch upon
+another aspect of it.  What are these variations in structure which succeed
+one another in the life-history of an organism?  I am conscious that I am
+here on the threshold of a chamber which contains the clue to some of our
+difficulties, and that I cannot enter it.  Looked at from one point of view
+they belong to the class of genetic variations, which depend upon the
+structure or constitution of the protoplasm; but instead of appearing in
+different zygotes (A zygote is a fertilised ovum, i.e. a new organism
+resulting from the fusion of an ovum and a spermatozoon.), they are present
+in the same zygote though at different times in its life-history.  They are
+of the same order as the mutational variations of the modern biologist upon
+which the appearance of a new character depends.  What is a genetic or
+mutational variation?  It is a genetic character which was not present in
+either of the parents.  But these "growth variations" were present in the
+parents, and in this they differ from mutational variations.  But what are
+genetic characters?  They are characters which must appear if any
+development occurs.  They are usually contrasted with "acquired
+characters," using the expression "acquired character" in the Lamarckian
+sense.  But strictly speaking they ARE acquired characters, for the zygote
+at first has none of the characters which it subsequently acquires, but
+only the power of acquiring them in response to the action of the
+environment.  But the characters so acquired are not what we technically
+understand and what Lamarck meant by "acquired characters."  They are
+genetic characters, as defined above.  What then are Lamarck's "acquired
+characters"?  They are variations in genetic characters caused in a
+particular way.  There are, in fact, two kinds of variation in genetic
+characters depending on the mode of causation.  Firstly, there are those
+variations consequent upon a variation in the constitution of the
+protoplasm of a particular zygote, and independent of the environment in
+which the organism develops, save in so far as this simply calls them
+forth:  these are the so-called genetic or mutational variations. 
+Secondly, there are those variations which occur in zygotes of similar
+germinal constitution and which are caused solely by differences in the
+environment to which the individuals are respectively exposed:  these are
+the "acquired characters" of Lamarck and of authors generally.  In
+consequence of this double sense in which the term "acquired characters"
+may be used, great confusion may and does occur.  If the protoplasm be
+compared to a machine, and the external conditions to the hand that works
+the machine, then it may be said that, as the machine can only work in one
+way, it can only produce one kind of result (genetic character), but the
+particular form or quality (Lamarckian "acquired character") of the result
+will depend upon the hand that works the machine (environment), just as the
+quality of the sound produced by a fiddle depends entirely upon the hand
+which plays upon it.  It would be improper to apply the term "mutation" to
+those genetic characters which are not new characters or new variants of
+old characters, but such genetic characters are of the same nature as those
+characters to which the term mutation has been applied.  It may be noticed
+in passing that it is very questionable if the modern biologist has acted
+in the real interests of science in applying the term mutation in the sense
+in which he has applied it.  The genetic characters of organisms come from
+one of two sources:  either they are old characters and are due to the
+action of what we call inheritance or they are new and are due to what we
+call variation.  If the term mutation is applied to the actual alteration
+of the machinery of the protoplasm, no objection can be felt to its use;
+but if it be applied, as it is, to the product of the action of the altered
+machine, viz. to the new genetic character, it leads to confusion. 
+Inheritance is the persistence of the structure of the machine; characters
+are the products of the working of the machine; variation in genetic
+characters is due to the alteration (mutation) in the arrangement of the
+machinery, while variation in acquired characters (Lamarckian) is due to
+differences in the mode of working the machinery.  The machinery when it
+starts (in the new zygote) has the power of grinding out certain results,
+which we call the characters of the organism.  These appear at successive
+intervals of time, and the orderly manifestation of them is what we call
+the life-history of the organism.  This brings us back to the question with
+which we started this discussion, viz. what is the relation of these
+variations in structure, which successively appear in an organism and
+constitute its life-history, to the mutational variations which appear in
+different organisms of the same brood or species.  The question is brought
+home to us when we ask what is a bud-sport, such as a nectarine appearing
+on a peach-tree?  From one point of view, it is simply a mutation appearing
+in asexual reproduction; from another it is one of these successional
+characters ("growth variations") which constitute the life-history of the
+zygote, for it appears in the same zygote which first produces a peach. 
+Here our analogy of a machine which only works in one way seems to fail us,
+for these bud-sports do not appear in all parts of the organism, only in
+certain buds or parts of it, so that one part of the zygotic machine would
+appear to work differently to another.  To discuss this question further
+would take us too far from our subject.  Suffice it to say that we cannot
+answer it, any more than we can this further question of burning interest
+at the present day, viz. to what extent and in what manner is the machine
+itself altered by the particular way in which it is worked.  In connection
+with this question we can only submit one consideration:  the zygotic
+machine can, by its nature, only work once, so that any alteration in it
+can only be ascertained by studying the replicas of it which are produced
+in the reproductive organs.
+
+It is a peculiarity that the result which we call the ripening of the
+generative organs nearly always appears among the final products of the
+action of the zygotic machine.  It is remarkable that this should be the
+case.  What is the reason of it?  The late appearance of functional
+reproductive organs is almost a universal law, and the explanation of it is
+suggested by expressing the law in another way, viz. that the machine is
+almost always so constituted that it ceases to work efficiently soon after
+the reproductive organs have sufficiently discharged their function.  Why
+this should occur we cannot explain:  it is an ultimate fact of nature, and
+cannot be included in any wider category.  The period during which the
+reproductive organs can act may be short as in ephemerids or long as in man
+and trees, and there is no reason to suppose that their action damages the
+vital machinery, though sometimes, as in the case of annual plants
+(Metschnikoff), it may incidentally do so; but, long or short, the
+cessation of their actions is always a prelude to the end.  When they and
+their action are impaired, the organism ceases to react with precision to
+the environment, and the organism as a whole undergoes retrogressive
+changes.
+
+It has been pointed out above that there is reason to believe that at the
+dawn of life the life-cycle was, EITHER IN ESSE OR IN POSSE, at least as
+long as it is at the present time.  The qualification implied by the words
+in italics is necessary, for it is clearly possible that the external
+conditions then existing were not suitable for the production of all the
+stages of the potential life-history, and that what we call organic
+evolution has consisted in a gradual evolution of new environments to which
+the organism's innate capacity of change has enabled it to adapt itself. 
+We have warrant for this possibility in the case of the Axolotl and in
+other similar cases of neoteny.  And these cases further bring home to us
+the fact, to which I have already referred, that the full development of
+the functional reproductive organs is nearly always associated with the
+final stages of the life-history.
+
+On this view of the succession of characters in the life-history of
+organisms, how shall we explain the undoubted fact that the development of
+buds hardly ever presents any phenomena corresponding to the embryonic and
+larval changes?  The reason is clearly this, that budding usually occurs
+after the embryonic stage is past; when the characters of embryonic life
+have been worked out by the machine.  When it takes place at an early stage
+in embryonic life, as it does in cases of so-called embryonic fission, the
+product shows, either partly or entirely, phenomena similar to those of
+embryonic development.  The only case known to me in which budding by the
+adult is accompanied by morphological features similar to those displayed
+by embryos is furnished by the budding of the medusiform spore-sacs of
+hydrozoon polyps.  But this case is exceptional, for here we have to do
+with an attempt, which fails, to form a free-swimming organism, the medusa;
+and the vestiges which appear in the buds are the umbrella-cavity, marginal
+tentacles, circular canal, etc., of the medusa arrested in development.
+
+But the question still remains, are there no cases in which, as implied by
+the recapitulation theory, variations in any organ are confined to the
+period in which the organ is functional and do not affect it in the
+embryonic stages?  The teeth of the whalebone whales may be cited as a case
+in which this is said to occur; but here the teeth are only imperfectly
+developed in the embryo and are soon absorbed.  They have been affected by
+the change which has produced their disappearance in the adult, but not to
+complete extinction.  Nor are they now likely to be extinguished, for
+having become exclusively embryonic they are largely protected from the
+action of natural selection.  This consideration brings up a most important
+aspect of the question, so far as disappearing organs are concerned.  Every
+organ is laid down at a certain period in the embryo and undergoes a
+certain course of growth until it obtains full functional development. 
+When for any cause reduction begins, it is affected at all stages of its
+growth, unless it has functional importance in the larva, and in some cases
+its life is shortened at one or both ends.  In cases, as in that of the
+whale's teeth, in which it entirely disappears in the adult, the latter
+part of its life is cut off; in others, the beginning of its life may be
+deferred.  This happens, for instance, with the spiracle of many
+Elasmobranchs, which makes its appearance after the hyobranchial cleft, not
+before it as it should do, being anterior to it in position, and as it does
+in the Amniota in which it shows no reduction in size as compared with the
+other pharyngeal clefts.  In those Elasmobranchs in which it is absent in
+the adult but present in the embryo (e.g. Carcharias) its life is shortened
+at both ends.  Many more instances of organs, of which the beginning and
+end have been cut off, might be mentioned; e.g. the muscle-plate coelom of
+Aves, the primitive streak and the neurenteric canal of amniote
+blastoderms.  In yet other cases in which the reduced organ is almost on
+the verge of disappearance, it may appear for a moment and disappear more
+than once in the course of development.  As an instance of this striking
+phenomenon I may mention the neurenteric canal of avine embryos, and the
+anterior neuropore of Ascidians.  Lastly the reduced organ may disappear in
+the developing stages before it does so in the adult.  As an instance of
+this may be mentioned the mandibular palp of those Crustacea with zoaea
+larvae.  This structure disappears in the larva only to reappear in a
+reduced form in later stages.  In all these cases we are dealing with an
+organ which, we imagine, attained a fuller functional development at some
+previous stage in race-history, but in most of them we have no proof that
+it did so.  It may be, and the possibility must not be lost sight of, that
+these organs never were anything else than functionless and that though
+they have been got rid of in the adult by elimination in the course of
+time, they have been able to persist in embryonic stages which are
+protected from the full action of natural selection.  There is no reason to
+suppose that living matter at its first appearance differed from non-living
+matter in possessing only properties conducive to its well-being and
+prolonged existence.  No one thinks that the properties of the various
+forms of inorganic matter are all strictly related to external conditions.
+Of what use to the diamond is its high specific gravity and high
+refrangibility, and to gold of its yellow colour and great weight?  These
+substances continue to exist in virtue of other properties than these.  It
+is impossible to suppose that the properties of living matter at its first
+appearance were all useful to it, for even now after aeons of elimination
+we find that it possesses many useless organs and that many of its
+relations to the external world are capable of considerable improvement.
+
+In writing this essay I have purposely refrained from taking a definite
+position with regard to the problems touched.  My desire has been to write
+a chapter showing the influence of Darwin's work so far as Embryology is
+concerned, and the various points which come up for consideration in
+discussing his views.  Darwin was the last man who would have claimed
+finality for any of his doctrines, but he might fairly have claimed to have
+set going a process of intellectual fermentation which is still very far
+from completion.
+
+
+XI.  THE PALAEONTOLOGICAL RECORD.
+
+I.  ANIMALS.
+
+By W.B. SCOTT.
+Professor of Geology in the University of Princeton, U.S.A.
+
+To no branch of science did the publication of "The Origin of Species"
+prove to be a more vivifying and transforming influence than to
+Palaeontology.  This science had suffered, and to some extent, still
+suffers from its rather anomalous position between geology and biology,
+each of which makes claim to its territory, and it was held in strict
+bondage to the Linnean and Cuvierian dogma that species were immutable
+entities.  There is, however, reason to maintain that this strict bondage
+to a dogma now abandoned, was not without its good side, and served the
+purpose of keeping the infant science in leading-strings until it was able
+to walk alone, and preventing a flood of premature generalisations and
+speculations.
+
+As Zittel has said:  "Two directions were from the first apparent in
+palaeontological research--a stratigraphical and a biological. 
+Stratigraphers wished from palaeontology mainly confirmation regarding the
+true order or relative age of zones of rock-deposits in the field. 
+Biologists had, theoretically at least, the more genuine interest in fossil
+organisms as individual forms of life."  (Zittel, "History of Geology and
+Palaeontology", page 363, London, 1901.)  The geological or stratigraphical
+direction of the science was given by the work of William Smith, "the
+father of historical geology," in the closing decade of the eighteenth
+century.  Smith was the first to make a systematic use of fossils in
+determining the order of succession of the rocks which make up the
+accessible crust of the earth, and this use has continued, without
+essential change, to the present day.  It is true that the theory of
+evolution has greatly modified our conceptions concerning the introduction
+of new species and the manner in which palaeontological data are to be
+interpreted in terms of stratigraphy, but, broadly speaking, the method
+remains fundamentally the same as that introduced by Smith.
+
+The biological direction of palaeontology was due to Cuvier and his
+associates, who first showed that fossils were not merely varieties of
+existing organisms, but belonged to extinct species and genera, an
+altogether revolutionary conception, which startled the scientific world. 
+Cuvier made careful studies, especially of fossil vertebrates, from the
+standpoint of zoology and was thus the founder of palaeontology as a
+biological science.  His great work on "Ossements Fossiles" (Paris, 1821)
+has never been surpassed as a masterpiece of the comparative method of
+anatomical investigation, and has furnished to the palaeontologist the
+indispensable implements of research.
+
+On the other hand, Cuvier's theoretical views regarding the history of the
+earth and its successive faunas and floras are such as no one believes to-
+day.  He held that the earth had been repeatedly devastated by great
+cataclysms, which destroyed every living thing, necessitating an entirely
+new creation, thus regarding the geological periods as sharply demarcated
+and strictly contemporaneous for the whole earth, and each species of
+animal and plant as confined to a single period.  Cuvier's immense
+authority and his commanding personality dominated scientific thought for
+more than a generation and marked out the line which the development of
+palaeontology was to follow.  The work was enthusiastically taken up by
+many very able men in the various European countries and in the United
+States, but, controlled as it was by the belief in the fixity of species,
+it remained almost entirely descriptive and consisted in the description
+and classification of the different groups of fossil organisms.  As already
+intimated, this narrowness of view had its compensations, for it deferred
+generalisations until some adequate foundations for these had been laid.
+
+Dominant as it was, Cuvier's authority was slowly undermined by the
+progress of knowledge and the way was prepared for the introduction of more
+rational conceptions.  The theory of "Catastrophism" was attacked by
+several geologists, most effectively by Sir Charles Lyell, who greatly
+amplified the principles enunciated by Hutton and Playfair in the preceding
+century, and inaugurated a new era in geology.  Lyell's uniformitarian
+views of the earth's history and of the agencies which had wrought its
+changes, had undoubted effect in educating men's minds for the acceptance
+of essentially similar views regarding the organic world.  In palaeontology
+too the doctrine of the immutability of species, though vehemently
+maintained and reasserted, was gradually weakening.  In reviewing long
+series of fossils, relations were observed which pointed to genetic
+connections and yet were interpreted as purely ideal.  Agassiz, for
+example, who never accepted the evolutionary theory, drew attention to
+facts which could be satisfactorily interpreted only in terms of that
+theory.  Among the fossils he indicated "progressive," "synthetic,"
+"prophetic," and "embryonic" types, and pointed out the parallelism which
+obtains between the geological succession of ancient animals and the
+ontogenetic development of recent forms.  In Darwin's words:  "This view
+accords admirably well with our theory."  ("Origin of Species" (6th
+edition), page 310.)  Of similar import were Owen's views on "generalised
+types" and "archetypes."
+
+The appearance of "The Origin of Species" in 1859 revolutionised all the
+biological sciences.  From the very nature of the case, Darwin was
+compelled to give careful consideration to the palaeontological evidence;
+indeed, it was the palaeontology and modern distribution of animals in
+South America which first led him to reflect upon the great problem.  In
+his own words:  "I had been deeply impressed by discovering in the Pampean
+formation great fossil animals covered with armour like that on the
+existing armadillos; secondly, by the manner in which closely allied
+animals replace one another in proceeding southward over the Continent; and
+thirdly, by the South American character of most of the productions of the
+Galapagos archipelago, and more especially by the manner in which they
+differ slightly on each island of the group."  ("Life and Letters of
+Charles Darwin", I. page 82.)  In the famous tenth and eleventh chapters of
+the "Origin", the palaeontological evidence is examined at length and the
+imperfection of the geological record is strongly emphasised.  The
+conclusion is reached, that, in view of this extreme imperfection,
+palaeontology could not reasonably be expected to yield complete and
+convincing proof of the evolutionary theory.  "I look at the geological
+record as a history of the world imperfectly kept, and written in a
+changing dialect; of this history we possess the last volume alone,
+relating only to two or three countries.  Of this volume, only here and
+there a short chapter has been preserved; and of each page, only here and
+there a few lines."  ("Origin of Species", page 289.)  Yet, aside from
+these inevitable difficulties, he concludes, that "the other great leading
+facts in palaeontology agree admirably with the theory of descent with
+modification through variation and natural selection."  (Ibid. page 313.)
+
+Darwin's theory gave an entirely new significance and importance to
+palaeontology.  Cuvier's conception of the science had been a limited,
+though a lofty one.  "How glorious it would be if we could arrange the
+organised products of the universe in their chronological order!...The
+chronological succession of organised forms, the exact determination of
+those types which appeared first, the simultaneous origin of certain
+species and their gradual decay, would perhaps teach us as much about the
+mysteries of organisation as we can possibly learn through experiments with
+living organisms."  (Zittel op. cit. page 140.)  This, however, was rather
+the expression of a hope for the distant future than an account of what was
+attainable, and in practice the science remained almost purely descriptive,
+until Darwin gave it a new standpoint, new problems and an altogether fresh
+interest and charm.  The revolution thus accomplished is comparable only to
+that produced by the Copernican astronomy.
+
+From the first it was obvious that one of the most searching tests of the
+evolutionary theory would be given by the advance of palaeontological
+discovery.  However imperfect the geological record might be, its
+ascertained facts would necessarily be consistent, under any reasonable
+interpretation, with the demands of a true theory; otherwise the theory
+would eventually be overwhelmed by the mass of irreconcilable data.  A very
+great stimulus was thus given to geological investigation and to the
+exploration of new lands.  In the last forty years, the examination of
+North and South America, of Africa and Asia has brought to light many
+chapters in the history of life, which are astonishingly full and complete. 
+The flood of new material continues to accumulate at such a rate that it is
+impossible to keep abreast of it, and the very wealth of the collections is
+a source of difficulty and embarrassment.  In modern palaeontology
+phylogenetic questions and problems occupy a foremost place and, as a
+result of the labours of many eminent investigators in many lands, it may
+be said that this science has proved to be one of the most solid supports
+of Darwin's theory.  True, there are very many unsolved problems, and the
+discouraged worker is often tempted to believe that the fossils raise more
+questions than they answer.  Yet, on the other hand, the whole trend of the
+evidence is so strongly in favour of the evolutionary doctrine, that no
+other interpretation seems at all rational.
+
+To present any adequate account of the palaeontological record from the
+evolutionary standpoint, would require a large volume and a singularly
+unequal, broken and disjointed history it would be.  Here the record is
+scanty, interrupted, even unintelligible, while there it is crowded with
+embarrassing wealth of material, but too often these full chapters are
+separated by such stretches of unrecorded time, that it is difficult to
+connect them.  It will be more profitable to present a few illustrative
+examples than to attempt an outline of the whole history.
+
+At the outset, the reader should be cautioned not to expect too much, for
+the task of determining phylogenies fairly bristles with difficulties and
+encounters many unanswered questions.  Even when the evidence seems to be
+as copious and as complete as could be wished, different observers will put
+different interpretations upon it, as in the notorious case of the
+Steinheim shells.  (In the Miocene beds of Steinheim, Wurtemberg, occur
+countless fresh-water shells, which show numerous lines of modification,
+but these have been very differently interpreted by different writers.) 
+The ludicrous discrepances which often appear between the phylogenetic
+"trees" of various writers have cast an undue discredit upon the science
+and have led many zoologists to ignore palaeontology altogether as unworthy
+of serious attention.  One principal cause of these discrepant and often
+contradictory results is our ignorance concerning the exact modes of
+developmental change.  What one writer postulates as almost axiomatic,
+another will reject as impossible and absurd.  Few will be found to agree
+as to how far a given resemblance is offset by a given unlikeness, and so
+long as the question is one of weighing evidence and balancing
+probabilities, complete harmony is not to be looked for.  These formidable
+difficulties confront us even in attempting to work out from abundant
+material a brief chapter in the phylogenetic history of some small and
+clearly limited group, and they become disproportionately greater, when we
+extend our view over vast periods of time and undertake to determine the
+mutual relationships of classes and types.  If the evidence were complete
+and available, we should hardly be able to unravel its infinite complexity,
+or to find a clue through the mazes of the labyrinth.  "Our ideas of the
+course of descent must of necessity be diagrammatic."  (D.H. Scott,
+"Studies in Fossil Botany", page 524.  London, 1900.)
+
+Some of the most complete and convincing examples of descent with
+modification are to be found among the mammals, and nowhere more abundantly
+than in North America, where the series of continental formations, running
+through the whole Tertiary period, is remarkably full.  Most of these
+formations contain a marvellous wealth of mammalian remains and in an
+unusual state of preservation.  The oldest Eocene (Paleocene) has yielded a
+mammalian fauna which is still of prevailingly Mesozoic character, and
+contains but few forms which can be regarded as ancestral to those of later
+times.  The succeeding fauna of the lower Eocene proper (Wasatch stage) is
+radically different and, while a few forms continue over from the
+Paleocene, the majority are evidently recent immigrants from some region
+not yet identified.  From the Wasatch onward, the development of many phyla
+may be traced in almost unbroken continuity, though from time to time the
+record is somewhat obscured by migrations from the Old World and South
+America.  As a rule, however, it is easy to distinguish between the
+immigrant and the indigenous elements of the fauna.
+
+From their gregarious habits and individual abundance, the history of many
+hoofed animals is preserved with especial clearness.  So well known as to
+have become a commonplace, is the phylogeny of the horses, which, contrary
+to all that would have been expected, ran the greater part of its course in
+North America.  So far as it has yet been traced, the line begins in the
+lower Eocene with the genus Eohippus, a little creature not much larger
+than a cat, which has a short neck, relatively short limbs, and in
+particular, short feet, with four functional digits and a splint-like
+rudiment in the fore-foot, three functional digits and a rudiment in the
+hind-foot.  The forearm bones (ulna and radius) are complete and separate,
+as are also the bones of the lower leg (fibula and tibia).  The skull has a
+short face, with the orbit, or eye-socket, incompletely enclosed with bone,
+and the brain-case is slender and of small capacity.  The teeth are short-
+crowned, the incisors without "mark," or enamel pit, on the cutting edge;
+the premolars are all smaller and simpler than the molars.  The pattern of
+the upper molars is so entirely different from that seen in the modern
+horses that, without the intermediate connecting steps, no one would have
+ventured to derive the later from the earlier plan.  This pattern is
+quadritubercular, with four principal, conical cusps arranged in two
+transverse pairs, forming a square, and two minute cuspules between each
+transverse pair, a tooth which is much more pig-like than horse-like.  In
+the lower molars the cusps have already united to form two crescents, one
+behind the other, forming a pattern which is extremely common in the early
+representatives of many different families, both of the Perissodactyla and
+the Artiodactyla.  In spite of the manifold differences in all parts of the
+skeleton between Eohippus and the recent horses, the former has stamped
+upon it an equine character which is unmistakable, though it can hardly be
+expressed in words.
+
+Each one of the different Eocene and Oligocene horizons has its
+characteristic genus of horses, showing a slow, steady progress in a
+definite direction, all parts of the structure participating in the
+advance.  It is not necessary to follow each of these successive steps of
+change, but it should be emphasised that the changes are gradual and
+uninterrupted.  The genus Mesohippus, of the middle Oligocene, may be
+selected as a kind of half-way stage in the long progression.  Comparing
+Mesohippus with Eohippus, we observe that the former is much larger, some
+species attaining the size of a sheep, and has a relatively longer neck,
+longer limbs and much more elongate feet, which are tridactyl, and the
+middle toe is so enlarged that it bears most of the weight, while the
+lateral digits are very much more slender.  The fore-arm bones have begun
+to co-ossify and the ulna is greatly reduced, while the fibula, though
+still complete, is hardly more than a thread of bone.  The skull has a
+longer face and a nearly enclosed orbit, and the brain-case is fuller and
+more capacious, the internal cast of which shows that the brain was richly
+convoluted.  The teeth are still very short-crowned, but the upper incisors
+plainly show the beginning of the "mark"; the premolars have assumed the
+molar form, and the upper molars, though plainly derived from those of
+Eohippus, have made a long stride toward the horse pattern, in that the
+separate cusps have united to form a continuous outer wall and two
+transverse crests.
+
+In the lower Miocene the interesting genus Desmatippus shows a further
+advance in the development of the teeth, which are beginning to assume the
+long-crowned shape, delaying the formation of roots; a thin layer of cement
+covers the crowns, and the transverse crests of the upper grinding teeth
+display an incipient degree of their modern complexity.  This tooth-pattern
+is strictly intermediate between the recent type and the ancient type seen
+in Mesohippus and its predecessors.  The upper Miocene genera, Protohippus
+and Hipparion are, to all intents and purposes, modern in character, but
+their smaller size, tridactyl feet and somewhat shorter-crowned teeth are
+reminiscences of their ancestry.
+
+From time to time, when a land-connection between North America and Eurasia
+was established, some of the successive equine genera migrated to the Old
+World, but they do not seem to have gained a permanent footing there until
+the end of the Miocene or beginning of the Pliocene, eventually
+diversifying into the horses, asses, and zebras of Africa, Asia and Europe. 
+At about the same period, the family extended its range to South America
+and there gave rise to a number of species and genera, some of them
+extremely peculiar.  For some unknown reason, all the horse tribe had
+become extinct in the western hemisphere before the European discovery, but
+not until after the native race of man had peopled the continents.
+
+In addition to the main stem of equine descent, briefly considered in the
+foregoing paragraphs, several side-branches were given off at successive
+levels of the stem.  Most of these branches were short-lived, but some of
+them flourished for a considerable period and ramified into many species.
+
+Apparently related to the horses and derived from the same root-stock is
+the family of the Palaeotheres, confined to the Eocene and Oligocene of
+Europe, dying out without descendants.  In the earlier attempts to work out
+the history of the horses, as in the famous essay of Kowalevsky ("Sur
+l'Anchitherium aurelianense Cuv. et sur l'histoire paleontologique des
+Chevaux", "Mem. de l'Acad. Imp. des Sc. de St Petersbourg", XX. no. 5,
+1873.), the Palaeotheres were placed in the direct line, because the number
+of adequately known Eocene mammals was then so small, that Cuvier's types
+were forced into various incongruous positions, to serve as ancestors for
+unrelated series.
+
+The American family of the Titanotheres may also be distantly related to
+the horses, but passed through an entirely different course of development. 
+From the lower Eocene to the lower sub-stage of the middle Oligocene the
+series is complete, beginning with small and rather lightly built animals.
+Gradually the stature and massiveness increase, a transverse pair of nasal
+horns make their appearance and, as these increase in size, the canine
+tusks and incisors diminish correspondingly.  Already in the oldest known
+genus the number of digits had been reduced to four in the fore-foot and
+three in the hind, but there the reduction stops, for the increasing body-
+weight made necessary the development of broad and heavy feet.  The final
+members of the series comprise only large, almost elephantine animals, with
+immensely developed and very various nasal horns, huge and massive heads,
+and altogether a grotesque appearance.  The growth of the brain did not at
+all keep pace with the increase of the head and body, and the ludicrously
+small brain may will have been one of the factors which determined the
+startlingly sudden disappearance and extinction of the group.
+
+Less completely known, but of unusual interest, is the genealogy of the
+rhinoceros family, which probably, though not certainly, was likewise of
+American origin.  The group in North America at least, comprised three
+divisions, or sub-families, of very different proportions, appearance and
+habits, representing three divergent lines from the same stem.  Though the
+relationship between the three lines seems hardly open to question, yet the
+form ancestral to all of them has not yet been identified.  This is because
+of our still very incomplete knowledge of several perissodactyl genera of
+the Eocene, any one of which may eventually prove to be the ancestor sought
+for.
+
+The first sub-family is the entirely extinct group of Hyracodonts, which
+may be traced in successive modifications through the upper Eocene, lower
+and middle Oligocene, then disappearing altogether.  As yet, the
+hyracodonts have been found only in North America, and the last genus of
+the series, Hyracodon, was a cursorial animal.  Very briefly stated, the
+modifications consist in a gradual increase in size, with greater
+slenderness of proportions, accompanied by elongation of the neck, limbs,
+and feet, which become tridactyl and very narrow.  The grinding teeth have
+assumed the rhinoceros-like pattern and the premolars resemble the molars
+in form; on the other hand, the front teeth, incisors and canines, have
+become very small and are useless as weapons.  As the animal had no horns,
+it was quite defenceless and must have found its safety in its swift
+running, for Hyracodon displays many superficial resemblances to the
+contemporary Oligocene horses, and was evidently adapted for speed.  It may
+well have been the competition of the horses which led to the extinction of
+these cursorial rhinoceroses.
+
+The second sub-family, that of the Amynodonts, followed a totally different
+course of development, becoming short-legged and short-footed, massive
+animals, the proportions of which suggest aquatic habits; they retained
+four digits in the front foot.  The animal was well provided with weapons
+in the large canine tusks, but was without horns.  Some members of this
+group extended their range to the Old World, but they all died out in the
+middle Oligocene, leaving no successors.
+
+The sub-family of the true rhinoceroses cannot yet be certainly traced
+farther back than to the base of the middle Oligocene, though some
+fragmentary remains found in the lower Oligocene are probably also
+referable to it.  The most ancient and most primitive member of this series
+yet discovered, the genus Trigonias, is unmistakably a rhinoceros, yet much
+less massive, having more the proportions of a tapir; it had four toes in
+the front foot, three in the hind, and had a full complement of teeth,
+except for the lower canines, though the upper canines are about to
+disappear, and the peculiar modification of the incisors, characteristic of
+the true rhinoceroses, is already apparent; the skull is hornless. 
+Representatives of this sub-family continue through the Oligocene and
+Miocene of North America, becoming rare and localised in the Pliocene and
+then disappearing altogether.  In the Old World, on the other hand, where
+the line appeared almost as early as it did in America, this group
+underwent a great expansion and ramification, giving rise not only to the
+Asiatic and African forms, but also to several extinct series.
+
+Turning now to the Artiodactyla, we find still another group of mammals,
+that of the camels and llamas, which has long vanished from North America,
+yet took its rise and ran the greater part of its course in that continent.
+From the lower Eocene onward the history of this series is substantially
+complete, though much remains to be learned concerning the earlier members
+of the family.  The story is very like that of the horses, to which in many
+respects it runs curiously parallel.  Beginning with very small, five-toed
+animals, we observe in the successive genera a gradual transformation in
+all parts of the skeleton, an elongation of the neck, limbs and feet, a
+reduction of the digits from five to two, and eventually the coalescence of
+the remaining two digits into a "cannon-bone."  The grinding teeth, by
+equally gradual steps, take on the ruminant pattern.  In the upper Miocene
+the line divides into the two branches of the camels and llamas, the former
+migrating to Eurasia and the latter to South America, though
+representatives of both lines persisted in North America until a very late
+period.  Interesting side-branches of this line have also been found, one
+of which ended in the upper Miocene in animals which had almost the
+proportions of the giraffes and must have resembled them in appearance.
+
+The American Tertiary has yielded several other groups of ruminant-like
+animals, some of which form beautifully complete evolutionary series, but
+space forbids more than this passing mention of them.
+
+It was in Europe that the Artiodactyla had their principal development, and
+the upper Eocene, Oligocene and Miocene are crowded with such an
+overwhelming number and variety of forms that it is hardly possible to
+marshal them in orderly array and determine their mutual relationships. 
+Yet in this chaotic exuberance of life, certain important facts stand out
+clearly, among these none is of greater interest and importance than the
+genealogy of the true Ruminants, or Pecora, which may be traced from the
+upper Eocene onward.  The steps of modification and change are very similar
+to those through which the camel phylum passed in North America, but it is
+instructive to note that, despite their many resemblances, the two series
+can be connected only in their far distant beginnings.  The pecoran stock
+became vastly more expanded and diversified than did the camel line and was
+evidently more plastic and adaptable, spreading eventually over all the
+continents except Australia, and forming to-day one of the dominant types
+of mammals, while the camels are on the decline and not far from
+extinction.  The Pecora successively ramified into the deer, antelopes,
+sheep, goats and oxen, and did not reach North America till the Miocene,
+when they were already far advanced in specialisation.  To this invasion of
+the Pecora, or true ruminants, it seems probable that the decline and
+eventual disappearance of the camels is to be ascribed.
+
+Recent discoveries in Egypt have thrown much light upon a problem which
+long baffled the palaeontologist, namely, the origin of the elephants. 
+(C.W. Andrews, "On the Evolution of the Proboscidea", "Phil. Trans. Roy.
+Soc." London, Vol. 196, 1904, page 99.)  Early representatives of this
+order, Mastodons, had appeared almost simultaneously (in the geological
+sense of that word) in the upper Miocene of Europe and North America, but
+in neither continent was any more ancient type known which could plausibly
+be regarded as ancestral to them.  Evidently, these problematical animals
+had reached the northern continents by migrating from some other region,
+but no one could say where that region lay.  The Eocene and Oligocene beds
+of the Fayoum show us that the region sought for is Africa, and that the
+elephants form just such a series of gradual modifications as we have found
+among other hoofed animals.  The later steps of the transformation, by
+which the mastodons lost their lower tusks, and their relatively small and
+simple grinding teeth acquired the great size and highly complex structure
+of the true elephants, may be followed in the uppermost Miocene and
+Pliocene fossils of India and southern Europe.
+
+Egypt has also of late furnished some very welcome material which
+contributes to the solution of another unsolved problem which had quite
+eluded research, the origin of the whales.  The toothed-whales may be
+traced back in several more or less parallel lines as far as the lower
+Miocene, but their predecessors in the Oligocene are still so incompletely
+known that safe conclusions can hardly be drawn from them.  In the middle
+Eocene of Egypt, however, has been found a small, whale-like animal
+(Protocetus), which shows what the ancestral toothed-whale was like, and at
+the same time seems to connect these thoroughly marine mammals with land-
+animals.  Though already entirely adapted to an aquatic mode of life, the
+teeth, skull and backbone of Protocetus display so many differences from
+those of the later whales and so many approximations to those of primitive,
+carnivorous land-mammals, as, in a large degree, to bridge over the gap
+between the two groups.  Thus one of the most puzzling of palaeontological
+questions is in a fair way to receive a satisfactory answer.  The origin of
+the whalebone-whales and their relations to the toothed-whales cannot yet
+be determined, since the necessary fossils have not been discovered.
+
+Among the carnivorous mammals, phylogenetic series are not so clear and
+distinct as among the hoofed animals, chiefly because the carnivores are
+individually much less abundant, and well-preserved skeletons are among the
+prizes of the collector.  Nevertheless, much has already been learned
+concerning the mutual relations of the carnivorous families, and several
+phylogenetic series, notably that of the dogs, are quite complete.  It has
+been made extremely probable that the primitive dogs of the Eocene
+represent the central stock, from which nearly or quite all the other
+families branched off, though the origin and descent of the cats have not
+yet been determined.
+
+It should be clearly understood that the foregoing account of mammalian
+descent is merely a selection of a few representative cases and might be
+almost indefinitely extended.  Nothing has been said, for example, of the
+wonderful museum of ancient mammalian life which is entombed in the rocks
+of South America, especially of Patagonia, and which opens a world so
+entirely different from that of the northern continents, yet exemplifying
+the same laws of "descent with modification."  Very beautiful phylogenetic
+series have already been established among these most interesting and
+marvellously preserved fossils, but lack of space forbids a consideration
+of them.
+
+The origin of the mammalia, as a class, offers a problem of which
+palaeontology can as yet present no definitive solution.  Many
+morphologists regard the early amphibia as the ancestral group from which
+the mammals were derived, while most palaeontologists believe that the
+mammals are descended from the reptiles.  The most ancient known mammals,
+those from the upper Triassic of Europe and North America, are so extremely
+rare and so very imperfectly known, that they give little help in
+determining the descent of the class, but, on the other hand, certain
+reptilian orders of the Permian period, especially well represented in
+South Africa, display so many and such close approximations to mammalian
+structure, as strongly to suggest a genetic relationship.  It is difficult
+to believe that all those likenesses should have been independently
+acquired and are without phylogenetic significance.
+
+Birds are comparatively rare as fossils and we should therefore look in
+vain among them for any such long and closely knit series as the mammals
+display in abundance.  Nevertheless, a few extremely fortunate discoveries
+have made it practically certain that birds are descended from reptiles, of
+which they represent a highly specialised branch.  The most ancient
+representative of this class is the extraordinary genus Archaeopteryx from
+the upper Jurassic of Bavaria, which, though an unmistakable bird, retains
+so many reptilian structures and characteristics as to make its derivation
+plain.  Not to linger over anatomical minutiae, it may suffice to mention
+the absence of a horny beak, which is replaced by numerous true teeth, and
+the long lizard-like tail, which is made up of numerous distinct vertebrae,
+each with a pair of quill-like feathers attached to it.  Birds with teeth
+are also found in the Cretaceous, though in most other respects the birds
+of that period had attained a substantially modern structure.  Concerning
+the interrelations of the various orders and families of birds,
+palaeontology has as yet little to tell us.
+
+The life of the Mesozoic era was characterised by an astonishing number and
+variety of reptiles, which were adapted to every mode of life, and
+dominated the air, the sea and the land, and many of which were of colossal
+proportions.  Owing to the conditions of preservation which obtained during
+the Mesozoic period, the history of the reptiles is a broken and
+interrupted one, so that we can make out many short series, rather than any
+one of considerable length.  While the relations of several reptilian
+orders can be satisfactorily determined, others still baffle us entirely,
+making their first known appearance in a fully differentiated state.  We
+can trace the descent of the sea-dragons, the Ichthyosaurs and Plesiosaurs,
+from terrestrial ancestors, but the most ancient turtles yet discovered
+show us no closer approximation to any other order than do the recent
+turtles; and the oldest known Pterosaurs, the flying dragons of the
+Jurassic, are already fully differentiated.  There is, however, no ground
+for discouragement in this, for the progress of discovery has been so rapid
+of late years, and our knowledge of Mesozoic life has increased with such
+leaps and bounds, that there is every reason to expect a solution of many
+of the outstanding problems in the near future.
+
+Passing over the lower vertebrates, for lack of space to give them any
+adequate consideration, we may briefly take up the record of invertebrate
+life.  From the overwhelming mass of material it is difficult to make a
+representative selection and even more difficult to state the facts
+intelligibly without the use of unduly technical language and without the
+aid of illustrations.
+
+Several groups of the Mollusca, or shell-fish, yield very full and
+convincing evidence of their descent from earlier and simpler forms, and of
+these none is of greater interest than the Ammonites, an extinct order of
+the cephalopoda.  The nearest living ally of the ammonites is the pearly
+nautilus, the other existing cephalopods, such as the squids, cuttle-fish,
+octopus, etc., are much more distantly related.  Like the nautilus, the
+ammonites all possess a coiled and chambered shell, but their especial
+characteristic is the complexity of the "sutures."  By sutures is meant the
+edges of the transverse partitions, or septa, where these join the shell-
+wall, and their complexity in the fully developed genera is extraordinary,
+forming patterns like the most elaborate oak-leaf embroidery, while in the
+nautiloids the sutures form simple curves.  In the rocks of the Mesozoic
+era, wherever conditions of preservation are favourable, these beautiful
+shells are stored in countless multitudes, of an incredible variety of
+form, size and ornamentation, as is shown by the fact that nearly 5000
+species have already been described.  The ammonites are particularly well
+adapted for phylogenetic studies, because, by removing the successive
+whorls of the coiled shell, the individual development may be followed back
+in inverse order, to the microscopic "protoconch," or embryonic shell,
+which lies concealed in the middle of the coil.  Thus the valuable aid of
+embryology is obtained in determining relationships.
+
+The descent of the ammonites, taken as a group, is simple and clear; they
+arose as a branch of the nautiloids in the lower Devonian, the shells known
+as goniatites having zigzag, angulated sutures.  Late in the succeeding
+Carboniferous period appear shells with a truly ammonoid complexity of
+sutures, and in the Permian their number and variety cause them to form a
+striking element of the marine faunas.  It is in the Mesozoic era, however,
+that these shells attain their full development; increasing enormously in
+the Triassic, they culminate in the Jurassic in the number of families,
+genera and species, in the complexity of the sutures, and in the variety of
+shell-ornamentation.  A slow decline begins in the Cretaceous, ending in
+the complete extinction of the whole group at the end of that period.  As a
+final phase in the history of the ammonites, there appear many so-called
+"abnormal" genera, in which the shell is irregularly coiled, or more or
+less uncoiled, in some forms becoming actually straight.  It is interesting
+to observe that some of these genera are not natural groups, but are
+"polyphyletic," i.e. are each derived from several distinct ancestral
+genera, which have undergone a similar kind of degeneration.
+
+In the huge assembly of ammonites it is not yet possible to arrange all the
+forms in a truly natural classification, which shall express the various
+interrelations of the genera, yet several beautiful series have already
+been determined.  In these series the individual development of the later
+general shows transitory stages which are permanent in antecedent genera. 
+To give a mere catalogue of names without figures would not make these
+series more intelligible.
+
+The Brachiopoda, or "lamp-shells," are a phylum of which comparatively few
+survive to the present day; their shells have a superficial likeness to
+those of the bivalved Mollusca, but are not homologous with the latter, and
+the phylum is really very distinct from the molluscs.  While greatly
+reduced now, these animals were incredibly abundant throughout the
+Palaeozoic era, great masses of limestone being often composed almost
+exclusively of their shells, and their variety is in keeping with their
+individual abundance.  As in the case of the ammonites, the problem is to
+arrange this great multitude of forms in an orderly array that shall
+express the ramifications of the group according to a genetic system.  For
+many brachiopods, both recent and fossil, the individual development, or
+ontogeny, has been worked out and has proved to be of great assistance in
+the problems of classification and phylogeny.  Already very encouraging
+progress has been made in the solution of these problems.  All brachiopods
+form first a tiny, embryonic shell, called the protegulum, which is
+believed to represent the ancestral form of the whole group, and in the
+more advanced genera the developmental stages clearly indicate the
+ancestral genera of the series, the succession of adult forms in time
+corresponding to the order of the ontogenetic stages.  The transformation
+of the delicate calcareous supports of the arms, often exquisitely
+preserved, are extremely interesting.  Many of the Palaeozoic genera had
+these supports coiled like a pair of spiral springs, and it has been shown
+that these genera were derived from types in which the supports were simply
+shelly loops.
+
+The long extinct class of crustacea known as the Trilobites are likewise
+very favourable subjects for phylogenetic studies.  So far as the known
+record can inform us, the trilobites are exclusively Palaeozoic in
+distribution, but their course must have begun long before that era, as is
+shown by the number of distinct types among the genera of the lower
+Cambrian.  The group reached the acme of abundance and relative importance
+in the Cambrian and Ordovician; then followed a long, slow decline, ending
+in complete and final disappearance before the end of the Permian.  The
+newly-hatched and tiny trilobite larva, known as the protaspis, is very
+near to the primitive larval form of all the crustacea.  By the aid of the
+correlated ontogenetic stages and the succession of the adult forms in the
+rocks, many phylogenetic series have been established and a basis for the
+natural arrangement of the whole class has been laid.
+
+Very instructive series may also be observed among the Echinoderms and,
+what is very rare, we are able in this sub-kingdom to demonstrate the
+derivation of one class from another.  Indeed, there is much reason to
+believe that the extinct class Cystidea of the Cambrian is the ancestral
+group, from which all the other Echinoderms, star-fishes, brittle-stars,
+sea-urchins, feather-stars, etc., are descended.
+
+The foregoing sketch of the palaeontological record is, of necessity,
+extremely meagre, and does not represent even an outline of the evidence,
+but merely a few illustrative examples, selected almost at random from an
+immense body of material.  However, it will perhaps suffice to show that
+the geological record is not so hopelessly incomplete as Darwin believed it
+to be.  Since "The Origin of Species" was written, our knowledge of that
+record has been enormously extended and we now possess, no complete
+volumes, it is true, but some remarkably full and illuminating chapters. 
+The main significance of the whole lies in the fact, that JUST IN
+PROPORTION TO THE COMPLETENESS OF THE RECORD IS THE UNEQUIVOCAL CHARACTER
+OF ITS TESTIMONY TO THE TRUTH OF THE EVOLUTIONARY THEORY.
+
+The test of a true, as distinguished from a false, theory is the manner in
+which newly discovered and unanticipated facts arrange themselves under it. 
+No more striking illustration of this can be found than in the contrasted
+fates of Cuvier's theory and of that of Darwin.  Even before Cuvier's death
+his views had been undermined and the progress of discovery soon laid them
+in irreparable ruin, while the activity of half-a-century in many different
+lines of inquiry has established the theory of evolution upon a foundation
+of ever growing solidity.  It is Darwin's imperishable glory that he
+prescribed the lines along which all the biological sciences were to
+advance to conquests not dreamed of when he wrote.
+
+
+XII.  THE PALAEONTOLOGICAL RECORD.
+
+II.  PLANTS.
+
+By D.H. SCOTT, F.R.S.
+President of the Linnean Society.
+
+There are several points of view from which the subject of the present
+essay may be regarded.  We may consider the fossil record of plants in its
+bearing:  I. on the truth of the doctrine of Evolution; II. on Phylogeny,
+or the course of Evolution; III. on the theory of Natural Selection.  The
+remarks which follow, illustrating certain aspects only of an extensive
+subject, may conveniently be grouped under these three headings.
+
+I.  THE TRUTH OF EVOLUTION.
+
+When "The Origin of Species" was written, it was necessary to show that the
+Geological Record was favourable to, or at least consistent with, the
+Theory of Descent.  The point is argued, closely and fully, in Chapter X. 
+"On the Imperfection of the Geological Record," and Chapter XI.  "On the
+Geological Succession of Organic Beings"; there is, however, little about
+plants in these chapters.  At the present time the truth of Evolution is no
+longer seriously disputed, though there are writers, like Reinke, who
+insist, and rightly so, that the doctrine is still only a belief, rather
+than an established fact of science.  (J. Reinke, "Kritische
+Abstammungslehre", "Wiesner-Festschrift", page 11, Vienna, 1908.) 
+Evidently, then, however little the Theory of Descent may be questioned in
+our own day, it is desirable to assure ourselves how the case stands, and
+in particular how far the evidence from fossil plants has grown stronger
+with time.
+
+As regards direct evidence for the derivation of one species from another,
+there has probably been little advance since Darwin wrote, at least so we
+must infer from the emphasis laid on the discontinuity of successive fossil
+species by great systematic authorities like Grand'Eury and Zeiller in
+their most recent writings.  We must either adopt the mutationist views of
+those authors (referred to in the last section of this essay) or must still
+rely on Darwin's explanation of the absence of numerous intermediate
+varieties.  The attempts which have been made to trace, in the Tertiary
+rocks, the evolution of recent species, cannot, owing to the imperfect
+character of the evidence, be regarded as wholly satisfactory.
+
+When we come to groups of a somewhat higher order we have an interesting
+history of the evolution of a recent family in the work, not yet completed,
+of Kidston and Gwynne-Vaughan on the fossil Osmundaceae.  ("Trans. Royal
+Soc. Edinburgh", Vol. 45, Part III. 1907, Vol. 46, Part II. 1908, Vol. 46,
+Part III. 1909.)  The authors are able, mainly on anatomical evidence, to
+trace back this now limited group of Ferns, through the Tertiary and
+Mesozoic to the Permian, and to show, with great probability, how their
+structure has been derived from that of early Palaeozoic types.
+
+The history of the Ginkgoaceae, now represented only by the isolated
+maidenhair tree, scarcely known in a wild state, offers another striking
+example of a family which can be traced with certainty to the older
+Mesozoic and perhaps further back still.  (See Seward and Gowan, "The
+Maidenhair Tree (Gingko biloba)", "Annals of Botany", Vol. XIV. 1900, page
+109; also A. Sprecher "Le Ginkgo biloba", L., Geneva, 1907.)
+
+On the wider question of the derivation of the great groups of plants, a
+very considerable advance has been made, and, so far as the higher plants
+are concerned, we are now able to form a far better conception than before
+of the probable course of evolution.  This is a matter of phylogeny, and
+the facts will be considered under that head; our immediate point is that
+the new knowledge of the relations between the classes of plants in
+question materially strengthens the case for the theory of descent.  The
+discoveries of the last few years throw light especially on the relation of
+the Angiosperms to the Gymnosperms, on that of the Seed-plants generally to
+the Ferns, and on the interrelations between the various classes of the
+higher Cryptogams.
+
+That the fossil record has not done still more for Evolution is due to the
+fact that it begins too late--a point on which Darwin laid stress ("Origin
+of Species" (6th edition), page 286.) and which has more recently been
+elaborated by Poulton.  ("Essays on Evolution", pages 46 et seq., Oxford,
+1908.)  An immense proportion of the whole evolutionary history lies behind
+the lowest fossiliferous rocks, and the case is worse for plants than for
+animals, as the record for the former begins, for all practical purposes,
+much higher up in the rocks.
+
+It may be well here to call attention to a question, often overlooked,
+which has lately been revived by Reinke.  (Reinke, loc. cit. page 13.)  As
+all admit, we know nothing of the origin of life; consequently, for all we
+can tell, it is as probable that life began, on this planet, with many
+living things, as with one.  If the first organic beings were many, they
+may have been heterogeneous, or at least exposed to different conditions,
+from their origin; in either case there would have been a number of
+distinct series from the beginning, and if so we should not be justified in
+assuming that all organisms are related to one another.  There may
+conceivably be several of the original lines of descent still surviving, or
+represented among extinct forms--to reverse the remark of a distinguished
+botanist, there may be several Vegetable Kingdoms!  However improbable this
+may sound, the possibility is one to be borne in mind.
+
+That all VASCULAR plants really belong to one stock seems certain, and here
+the palaeontological record has materially strengthened the case for a
+monophyletic history.  The Bryophyta are not likely to be absolutely
+distinct, for their sexual organs, and the stomata of the Mosses strongly
+suggest community of descent with the higher plants; if this be so it no
+doubt establishes a certain presumption in favour of a common origin for
+plants generally, for the gap between "Mosses and Ferns" has been regarded
+as the widest in the Vegetable Kingdom.  The direct evidence of
+consanguinity is however much weaker when we come to the Algae, and it is
+conceivable (even if improbable) that the higher plants may have had a
+distinct ancestry (now wholly lost) from the beginning.  The question had
+been raised in Darwin's time, and he referred to it in these words:  "No
+doubt it is possible, as Mr G.H. Lewes has urged, that at the first
+commencement of life many different forms were evolved; but if so, we may
+conclude that only a very few have left modified descendants."  ("Origin of
+Species", page 425.)  This question, though it deserves attention, does not
+immediately affect the subject of the palaeontological record of plants,
+for there can be no reasonable doubt as to the interrelationship of those
+groups on which the record at present throws light.
+
+The past history of plants by no means shows a regular progression from the
+simple to the complex, but often the contrary.  This apparent anomaly is
+due to two causes.
+
+1.  The palaeobotanical record is essentially the story of the successive
+ascendancy of a series of dominant families, each of which attained its
+maximum, in organisation as well as in extent, and then sank into
+comparative obscurity, giving place to other families, which under new
+conditions were better able to take a leading place.  As each family ran
+its downward course, either its members underwent an actual reduction in
+structure as they became relegated to herbaceous or perhaps aquatic life
+(this may have happened with the Horsetails and with Isoetes if derived
+from Lepidodendreae), or the higher branches of the family were crowded out
+altogether and only the "poor relations" were able to maintain their
+position by evading the competition of the ascendant races; this is also
+illustrated by the history of the Lycopod phylum.  In either case there
+would result a lowering of the type of organisation within the group.
+
+2.  The course of real progress is often from the complex to the simple. 
+If, as we shall find some grounds for believing, the Angiosperms came from
+a type with a flower resembling in its complexity that of Mesozoic
+"Cycads," almost the whole evolution of the flower in the highest plants
+has been a process of reduction.  The stamen, in particular, has
+undoubtedly become extremely simplified during evolution; in the most
+primitive known seed-plants it was a highly compound leaf or pinna; its
+reduction has gone on in the Conifers and modern Cycads, as well as in the
+Angiosperms, though in different ways and to a varying extent.
+
+The seed offers another striking example; the Palaeozoic seeds (if we leave
+the seed-like organs of certain Lycopods out of consideration) were always,
+so far as we know, highly complex structures, with an elaborate vascular
+system, a pollen-chamber, and often a much-differentiated testa.  In the
+present day such seeds exist only in a few Gymnosperms which retain their
+ancient characters--in all the higher Spermophytes the structure is very
+much simplified, and this holds good even in the Coniferae, where there is
+no countervailing complication of ovary and stigma.
+
+Reduction, in fact, is not always, or even generally, the same thing as
+degeneration.  Simplification of parts is one of the most usual means of
+advance for the organism as a whole.  A large proportion of the higher
+plants are microphyllous in comparison with the highly megaphyllous fern-
+like forms from which they appear to have been derived.
+
+Darwin treated the general question of advance in organisation with much
+caution, saying:  "The geological record...does not extend far enough back,
+to show with unmistakeable clearness that within the known history of the
+world organisation has largely advanced."  ("Origin of Species", page 308.) 
+Further on (Ibid. page 309.) he gives two standards by which advance may be
+measured:  "We ought not solely to compare the highest members of a class
+at any two periods...but we ought to compare all the members, high and low,
+at the two periods."  Judged by either standard the Horsetails and Club
+Mosses of the Carboniferous were higher than those of our own day, and the
+same is true of the Mesozoic Cycads.  There is a general advance in the
+succession of classes, but not within each class.
+
+Darwin's argument that "the inhabitants of the world at each successive
+period in its history have beaten their predecessors in the race for life,
+and are, in so far, higher in the scale" ("Origin of Species", page 315.)
+is unanswerable, but we must remember that "higher in the scale" only means
+"better adapted to the existing conditions."  Darwin points out (Ibid. page
+279.) that species have remained unchanged for long periods, probably
+longer than the periods of modification, and only underwent change when the
+conditions of their life were altered.  Higher organisation, judged by the
+test of success, is thus purely relative to the changing conditions, a fact
+of which we have a striking illustration in the sudden incoming of the
+Angiosperms with all their wonderful floral adaptations to fertilisation by
+the higher families of Insects.
+
+II.  PHYLOGENY.
+
+The question of phylogeny is really inseparable from that of the truth of
+the doctrine of evolution, for we cannot have historical evidence that
+evolution has actually taken place without at the same time having evidence
+of the course it has followed.
+
+As already pointed out, the progress hitherto made has been rather in the
+way of joining up the great classes of plants than in tracing the descent
+of particular species or genera of the recent flora.  There appears to be a
+difference in this respect from the Animal record, which tells us so much
+about the descent of living species, such as the elephant or the horse. 
+The reason for this difference is no doubt to be found in the fact that the
+later part of the palaeontological record is the most satisfactory in the
+case of animals and the least so in the case of plants.  The Tertiary
+plant-remains, in the great majority of instances, are impressions of
+leaves, the conclusions to be drawn from which are highly precarious; until
+the whole subject of Angiospermous palaeobotany has been reinvestigated, it
+would be rash to venture on any statements as to the descent of the
+families of Dicotyledons or Monocotyledons.
+
+Our attention will be concentrated on the following questions, all relating
+to the phylogeny of main groups of plants:  i. The Origin of the
+Angiosperms.  ii. The Origin of the Seed-plants.  iii. The Origin of the
+different classes of the Higher Cryptogamia.
+
+i.  THE ORIGIN OF THE ANGIOSPERMS.
+
+The first of these questions has long been the great crux of botanical
+phylogeny, and until quite recently no light had been thrown upon the
+difficulty.  The Angiosperms are the Flowering Plants, par excellence, and
+form, beyond comparison, the dominant sub-kingdom in the flora of our own
+age, including, apart from a few Conifers and Ferns, all the most familiar
+plants of our fields and gardens, and practically all plants of service to
+man.  All recent work has tended to separate the Angiosperms more widely
+from the other seed-plants now living, the Gymnosperms.  Vast as is the
+range of organisation presented by the great modern sub-kingdom, embracing
+forms adapted to every environment, there is yet a marked uniformity in
+certain points of structure, as in the development of the embryo-sac and
+its contents, the pollination through the intervention of a stigma, the
+strange phenomenon of double fertilisation (One sperm fertilising the egg,
+while the other unites with the embryo-sac nucleus, itself the product of a
+nuclear fusion, to give rise to a nutritive tissue, the endosperm.), the
+structure of the stamens, and the arrangement of the parts of the flower. 
+All these points are common to Monocotyledons and Dicotyledons, and
+separate the Angiosperms collectively from all other plants.
+
+In geological history the Angiosperms first appear in the Lower Cretaceous,
+and by Upper Cretaceous times had already swamped all other vegetation and
+seized the dominant position which they still hold.  Thus they are isolated
+structurally from the rest of the Vegetable Kingdom, while historically
+they suddenly appear, almost in full force, and apparently without
+intermediaries with other groups.  To quote Darwin's vigorous words:  "The
+rapid development, as far as we can judge, of all the higher plants within
+recent geological times is an abominable mystery."  ("More Letters of
+Charles Darwin", Vol. II. page 20, letter to J.D. Hooker, 1879.)  A couple
+of years later he made a bold suggestion (which he only called an "idle
+thought") to meet this difficulty.  He says: "I have been so astonished at
+the apparently sudden coming in of the higher phanerogams, that I have
+sometimes fancied that development might have slowly gone on for an immense
+period in some isolated continent or large island, perhaps near the South
+Pole."  (Ibid, page 26, letter to Hooker, 1881.)  This idea of an
+Angiospermous invasion from some lost southern land has sometimes been
+revived since, but has not, so far as the writer is aware, been supported
+by evidence.  Light on the problem has come from a different direction.
+
+The immense development of plants with the habit of Cycads, during the
+Mesozoic Period up to the Lower Cretaceous, has long been known.  The
+existing Order Cycadaceae is a small family, with 9 genera and perhaps 100
+species, occurring in the tropical and sub-tropical zones of both the Old
+and New World, but nowhere forming a dominant feature in the vegetation. 
+Some few attain the stature of small trees, while in the majority the stem
+is short, though often living to a great age.  The large pinnate or rarely
+bipinnate leaves give the Cycads a superficial resemblance in habit to
+Palms.  Recent Cycads are dioecious; throughout the family the male
+fructification is in the form of a cone, each scale of the cone
+representing a stamen, and bearing on its lower surface numerous pollen-
+sacs, grouped in sori like the sporangia of Ferns.  In all the genera,
+except Cycas itself, the female fructifications are likewise cones, each
+carpel bearing two ovules on its margin.  In Cycas, however, no female cone
+is produced, but the leaf-like carpels, bearing from two to six ovules
+each, are borne directly on the main stem of the plant in rosettes
+alternating with those of the ordinary leaves--the most primitive
+arrangement known in any living seed-plant.  The whole Order is relatively
+primitive, as shown most strikingly in its cryptogamic mode of
+fertilisation, by means of spermatozoids, which it shares with the
+maidenhair tree alone, among recent seed-plants.
+
+In all the older Mesozoic rocks, from the Trias to the Lower Cretaceous,
+plants of the Cycad class (Cycadophyta, to use Nathorst's comprehensive
+name) are extraordinarily abundant in all parts of the world; in fact they
+were almost as prominent in the flora of those ages as the Dicotyledons are
+in that of our own day.  In habit and to a great extent in anatomy, the
+Mesozoic Cycadophyta for the most part much resemble the recent Cycadaceae.
+But, strange to say, it is only in the rarest cases that the fructification
+has proved to be of the simple type characteristic of the recent family;
+the vast majority of the abundant fertile specimens yielded by the Mesozoic
+rocks possess a type of reproductive apparatus far more elaborate than
+anything known in Cycadaceae or other Gymnosperms.  The predominant
+Mesozoic family, characterised by this advanced reproductive organisation,
+is known as the Bennettiteae; in habit these plants resembled the more
+stunted Cycads of the recent flora, but differed from them in the presence
+of numerous lateral fructifications, like large buds, borne on the stem
+among the crowded bases of the leaves.  The organisation of these
+fructifications was first worked out on European specimens by Carruthers,
+Solms-Laubach, Lignier and others, but these observers had only more or
+less ripe fruits to deal with; the complete structure of the flower has
+only been elucidated within the last few years by the researches of Wieland
+on the magnificent American material, derived from the Upper Jurassic and
+Lower Cretaceous beds of Maryland, Dakota and Wyoming.  (G.R. Wieland,
+"American Fossil Cycads", Carnegie Institution, Washington, 1906.)  The
+word "flower" is used deliberately, for reasons which will be apparent from
+the following brief description, based on Wieland's observations.
+
+The fructification is attached to the stem by a thick stalk, which, in its
+upper part, bears a large number of spirally arranged bracts, forming
+collectively a kind of perianth and completely enclosing the essential
+organs of reproduction.  The latter consist of a whorl of stamens, of
+extremely elaborate structure, surrounding a central cone or receptacle
+bearing numerous ovules.  The stamens resemble the fertile fronds of a
+fern; they are of a compound, pinnate form, and bear very large numbers of
+pollen-sacs, each of which is itself a compound structure consisting of a
+number of compartments in which the pollen was formed.  In their lower part
+the stamens are fused together by their stalks, like the "monadelphous"
+stamens of a mallow.  The numerous ovules borne on the central receptacle
+are stalked, and are intermixed with sterile scales; the latter are
+expanded at their outer ends, which are united to form a kind of pericarp
+or ovary-wall, only interrupted by the protruding micropyles of the ovules. 
+There is thus an approach to the closed pistil of an Angiosperm, but it is
+evident that the ovules received the pollen directly.  The whole
+fructification is of large size; in the case of Cycadeoidea dacotensis, one
+of the species investigated by Wieland, the total length, in the bud
+condition, is about 12 cm., half of which belongs to the peduncle.
+
+The general arrangement of the organs is manifestly the same as in a
+typical Angiospermous flower, with a central pistil, a surrounding whorl of
+stamens and an enveloping perianth; there is, as we have seen, some
+approach to the closed ovary of an Angiosperm; another point, first
+discovered nearly 20 years ago by Solms-Laubach in his investigation of a
+British species, is that the seed was practically "exalbuminous," its
+cavity being filled by the large, dicotyledonous embryo, whereas in all
+known Gymnosperms a large part of the sac is occupied by a nutritive
+tissue, the prothallus or endosperm; here also we have a condition only met
+with elsewhere among the higher Flowering Plants.
+
+Taking all the characters into account, the indications of affinity between
+the Mesozoic Cycadophyta and the Angiosperms appear extremely significant,
+as was recognised by Wieland when he first discovered the hermaphrodite
+nature of the Bennettitean flower.  The Angiosperm with which he specially
+compared the fossil type was the Tulip tree (Liriodendron) and certainly
+there is a remarkable analogy with the Magnoliaceous flowers, and with
+those of related orders such as Ranunculaceae and the Water-lilies.  It
+cannot, of course, be maintained that the Bennettiteae, or any other
+Mesozoic Cycadophyta at present known, were on the direct line of descent
+of the Angiosperms, for there are some important points of difference, as,
+for example, in the great complexity of the stamens, and in the fact that
+the ovary-wall or pericarp was not formed by the carpels themselves, but by
+the accompanying sterile scale-leaves.  Botanists, since the discovery of
+the bisexual flowers of the Bennettiteae, have expressed different views as
+to the nearness of their relation to the higher Flowering Plants, but the
+points of agreement are so many that it is difficult to resist the
+conviction that a real relation exists, and that the ancestry of the
+Angiosperms, so long shrouded in complete obscurity, is to be sought among
+the great plexus of Cycad-like plants which dominated the flora of the
+world in Mesozoic times.  (On this subject see, in addition to Wieland's
+great work above cited, F.W. Oliver, "Pteridosperms and Angiosperms", "New
+Phytologist", Vol. V. 1906; D.H. Scott, "The Flowering Plants of the
+Mesozoic Age in the Light of Recent Discoveries", "Journal R. Microscop.
+Soc." 1907, and especially E.A.N. Arber and J. Parkin, "On the Origin of
+Angiosperms", "Journal Linn. Soc." (Bot.) Vol. XXXVIII. page 29, 1907.)
+
+The great complexity of the Bennettitean flower, the earliest known
+fructification to which the word "flower" can be applied without forcing
+the sense, renders it probable, as Wieland and others have pointed out,
+that the evolution of the flower in Angiosperms has consisted essentially
+in a process of reduction, and that the simplest forms of flower are not to
+be regarded as the most primitive.  The older morphologists generally took
+the view that such simple flowers were to be explained as reductions from a
+more perfect type, and this opinion, though abandoned by many later
+writers, appears likely to be true when we consider the elaboration of
+floral structure attained among the Mesozoic Cycadophyta, which preceded
+the Angiosperms in evolution.
+
+If, as now seems probable, the Angiosperms were derived from ancestors
+allied to the Cycads, it would naturally follow that the Dicotyledons were
+first evolved, for their structure has most in common with that of the
+Cycadophyta.  We should then have to regard the Monocotyledons as a side-
+line, diverging probably at a very early stage from the main dicotyledonous
+stock, a view which many botanists have maintained, of late, on other
+grounds.  (See especially Ethel Sargant, "The Reconstruction of a Race of
+Primitive Angiosperms", "Annals of Botany", Vol. XXII. page 121, 1908.)  So
+far, however, as the palaeontological record shows, the Monocotyledons were
+little if at all later in their appearance than the Dicotyledons, though
+always subordinate in numbers.  The typical and beautifully preserved Palm-
+wood from Cretaceous rocks is striking evidence of the early evolution of a
+characteristic monocotyledonous family.  It must be admitted that the whole
+question of the evolution of Monocotyledons remains to be solved.
+
+Accepting, provisionally, the theory of the cycadophytic origin of
+Angiosperms, it is interesting to see to what further conclusions we are
+led.  The Bennettiteae, at any rate, were still at the gymnospermous level
+as regards their pollination, for the exposed micropyles of the ovules were
+in a position to receive the pollen directly, without the intervention of a
+stigma.  It is thus indicated that the Angiosperms sprang from a
+gymnospermous source, and that the two great phyla of Seed-plants have not
+been distinct from the first, though no doubt the great majority of known
+Gymnosperms, especially the Coniferae, represent branch-lines of their own.
+
+The stamens of the Bennettiteae are arranged precisely as in an
+angiospermous flower, but in form and structure they are like the fertile
+fronds of a Fern, in fact the compound pollen-sacs, or synangia as they are
+technically called, almost exactly agree with the spore-sacs of a
+particular family of Ferns--the Marattiaceae, a limited group, now mainly
+tropical, which was probably more prominent in the later Palaeozoic times
+than at present.  The scaly hairs, or ramenta, which clothe every part of
+the plant, are also like those of Ferns.
+
+It is not likely that the characters in which the Bennettiteae resemble the
+Ferns came to them directly from ancestors belonging to that class; an
+extensive group of Seed-plants, the Pteridospermeae, existed in Palaeozoic
+times and bear evident marks of affinity with the Fern phylum.  The fern-
+like characters so remarkably persistent in the highly organised
+Cycadophyta of the Mesozoic were in all likelihood derived through the
+Pteridosperms, plants which show an unmistakable approach to the
+cycadophytic type.
+
+The family Bennettiteae thus presents an extraordinary association of
+characters, exhibiting, side by side, features which belong to the
+Angiosperms, the Gymnosperms and the Ferns.
+
+ii.  ORIGIN OF SEED-PLANTS.
+
+The general relation of the gymnospermous Seed-plants to the Higher
+Cryptogamia was cleared up, independently of fossil evidence, by the
+brilliant researches of Hofmeister, dating from the middle of the past
+century.  (W. Hofmeister, "On the Germination, Development and
+Fructification of the Higher Cryptogamia", Ray Society, London, 1862.  The
+original German treatise appeared in 1851.)  He showed that "the embryo-sac
+of the Coniferae may be looked upon as a spore remaining enclosed in its
+sporangium; the prothallium which it forms does not come to the light." 
+(Ibid. page 438.)  He thus determined the homologies on the female side. 
+Recognising, as some previous observers had already done, that the
+microspores of those Cryptogams in which two kinds of spore are developed,
+are equivalent to the pollen-grains of the higher plants, he further
+pointed out that fertilisation "in the Rhizocarpeae and Selaginellae takes
+place by free spermatozoa, and in the Coniferae by a pollen-tube, in the
+interior of which spermatozoa are probably formed"--a remarkable instance
+of prescience, for though spermatozoids have not been found in the Conifers
+proper, they were demonstrated in the allied groups Cycadaceae and Ginkgo,
+in 1896, by the Japanese botanists Ikeno and Hirase.  A new link was thus
+established between the Gymnosperms and the Cryptogams.
+
+It remained uncertain, however, from which line of Cryptogams the
+gymnospermous Seed-plants had sprung.  The great point of morphological
+comparison was the presence of two kinds of spore, and this was known to
+occur in the recent Lycopods and Water-ferns (Rhizocarpeae) and was also
+found in fossil representatives of the third phylum, that of the
+Horsetails.  As a matter of fact all the three great Cryptogamic classes
+have found champions to maintain their claim to the ancestry of the Seed-
+plants, and in every case fossil evidence was called in.  For a long time
+the Lycopods were the favourites, while the Ferns found the least support. 
+The writer remembers, however, in the year 1881, hearing the late Prof.
+Sachs maintain, in a lecture to his class, that the descent of the Cycads
+could be traced, not merely from Ferns, but from a definite family of
+Ferns, the Marattiaceae, a view which, though in a somewhat crude form,
+anticipated more modern ideas.
+
+Williamson appears to have been the first to recognise the presence, in the
+Carboniferous flora, of plants combining the characters of Ferns and
+Cycads.  (See especially his "Organisation of the Fossil Plants of the
+Coal-Measures", Part XIII. "Phil. Trans. Royal Soc." 1887 B. page 299.) 
+This conclusion was first reached in the case of the genera Heterangium and
+Lyginodendron, plants, which with a wholly fern-like habit, were found to
+unite an anatomical structure holding the balance between that of Ferns and
+Cycads, Heterangium inclining more to the former and Lyginodendron to the
+latter.  Later researches placed Williamson's original suggestion on a
+firmer basis, and clearly proved the intermediate nature of these genera,
+and of a number of others, so far as their vegetative organs were
+concerned.  This stage in our knowledge was marked by the institution of
+the class Cycadofilices by Potonie in 1897.
+
+Nothing, however, was known of the organs of reproduction of the
+Cycadofilices, until F.W. Oliver, in 1903, identified a fossil seed,
+Lagenostoma Lomaxi, as belonging to Lyginodendron, the identification
+depending, in the first instance, on the recognition of an identical form
+of gland, of very characteristic structure, on the vegetative organs of
+Lyginodendron and on the cupule enveloping the seed.  This evidence was
+supported by the discovery of a close anatomical agreement in other
+respects, as well as by constant association between the seed and the
+plant.  (F.W. Oliver and D.H. Scott, "On the Structure of the Palaeozoic
+Seed, Lagenostoma Lomaxi, etc." "Phil. Trans. Royal Soc." Vol. 197 B.
+1904.)  The structure of the seed of Lyginodendron, proved to be of the
+same general type as that of the Cycads, as shown especially by the
+presence of a pollen-chamber or special cavity for the reception of the
+pollen-grains, an organ only known in the Cycads and Ginkgo among recent
+plants.
+
+Within a few months after the discovery of the seed of Lyginodendron,
+Kidston found the large, nut-like seed of a Neuropteris, another fern-like
+Carboniferous plant, in actual connection with the pinnules of the frond,
+and since then seeds have been observed on the frond in species of
+Aneimites and Pecopteris, and a vast body of evidence, direct or indirect,
+has accumulated, showing that a large proportion of the Palaeozoic plants
+formerly classed as Ferns were in reality reproduced by seeds of the same
+type as those of recent Cycadaceae.  (A summary of the evidence will be
+found in the writer's article "On the present position of Palaeozoic
+Botany", "Progressus Rei Botanicae", 1907, page 139, and "Studies in Fossil
+Botany", Vol. II. (2nd edition) London, 1909.)  At the same time, the
+anatomical structure, where it is open to investigation, confirms the
+suggestion given by the habit, and shows that these early seed-bearing
+plants had a real affinity with Ferns.  This conclusion received strong
+corroboration when Kidston, in 1905, discovered the male organs of
+Lyginodendron, and showed that they were identical with a fructification of
+the genus Crossotheca, hitherto regarded as belonging to Marattiaceous
+Ferns.  (Kidston, "On the Microsporangia of the Pteridospermeae, etc." 
+"Phil. Trans. Royal Soc." Vol. 198, B. 1906.)
+
+The general conclusion which follows from the various observations alluded
+to, is that in Palaeozoic times there was a great body of plants
+(including, as it appears, a large majority of the fossils previously
+regarded as Ferns) which had attained the rank of Spermophyta, bearing
+seeds of a Cycadean type on fronds scarcely differing from the vegetative
+foliage, and in other respects, namely anatomy, habit and the structure of
+the pollen-bearing organs, retaining many of the characters of Ferns.  From
+this extensive class of plants, to which the name Pteridospermeae has been
+given, it can scarcely be doubted that the abundant Cycadophyta, of the
+succeeding Mesozoic period, were derived.  This conclusion is of far-
+reaching significance, for we have already found reason to think that the
+Angiosperms themselves sprang, in later times, from the Cycadophytic stock;
+it thus appears that the Fern-phylum, taken in a broad sense, ultimately
+represents the source from which the main line of descent of the
+Phanerogams took its rise.
+
+It must further be borne in mind that in the Palaeozoic period there
+existed another group of seed-bearing plants, the Cordaiteae, far more
+advanced than the Pteridospermeae, and in many respects approaching the
+Coniferae, which themselves begin to appear in the latest Palaeozoic rocks.
+The Cordaiteae, while wholly different in habit from the contemporary fern-
+like Seed-plants, show unmistakable signs of a common origin with them. 
+Not only is there a whole series of forms connecting the anatomical
+structure of the Cordaiteae with that of the Lyginodendreae among
+Pteridosperms, but a still more important point is that the seeds of the
+Cordaiteae, which have long been known, are of the same Cycadean type as
+those of the Pteridosperms, so that it is not always possible, as yet, to
+discriminate between the seeds of the two groups.  These facts indicate
+that the same fern-like stock which gave rise to the Cycadophyta and
+through them, as appears probable, to the Angiosperms, was also the source
+of the Cordaiteae, which in their turn show manifest affinity with some at
+least of the Coniferae.  Unless the latter are an artificial group, a view
+which does not commend itself to the writer, it would appear probable that
+the Gymnosperms generally, as well as the Angiosperms, were derived from an
+ancient race of Cryptogams, most nearly related to the Ferns.  (Some
+botanists, however, believe that the Coniferae, or some of them, are
+probably more nearly related to the Lycopods.  See Seward and Ford, "The
+Araucarieae, Recent and Extinct", "Phil. Trans. Royal Soc." Vol. 198 B.
+1906.)
+
+It may be mentioned here that the small gymnospermous group Gnetales
+(including the extraordinary West African plant Welwitschia) which were
+formerly regarded by some authorities as akin to the Equisetales, have
+recently been referred, on better grounds, to a common origin with the
+Angiosperms, from the Mesozoic Cycadophyta.
+
+The tendency, therefore, of modern work on the palaeontological record of
+the Seed-plants has been to exalt the importance of the Fern-phylum, which,
+on present evidence, appears to be that from which the great majority,
+possibly the whole, of the Spermophyta have been derived.
+
+One word of caution, however, is necessary.  The Seed-plants are of
+enormous antiquity; both the Pteridosperms and the more highly organised
+family Cordaiteae, go back as far in geological history (namely to the
+Devonian) as the Ferns themselves or any other Vascular Cryptogams.  It
+must therefore be understood that in speaking of the derivation of the
+Spermophyta from the Fern-phylum, we refer to that phylum at a very early
+stage, probably earlier than the most ancient period to which our record of
+land-plants extends.  The affinity between the oldest Seed-plants and the
+Ferns, in the widest sense, seems established, but the common stock from
+which they actually arose is still unknown; though no doubt nearer to the
+Ferns than to any other group, it must have differed widely from the Ferns
+as we now know them, or perhaps even from any which the fossil record has
+yet revealed to us.
+
+iii.  THE ORIGIN OF THE HIGHER CRYPTOGAMIA.
+
+The Sub-kingdom of the higher Spore-plants, the Cryptogamia possessing a
+vascular system, was more prominent in early geological periods than at
+present.  It is true that the dominance of the Pteridophyta in Palaeozoic
+times has been much exaggerated owing to the assumption that everything
+which looked like a Fern really was a Fern.  But, allowing for the fact,
+now established, that most of the Palaeozoic fern-like plants were already
+Spermophyta, there remains a vast mass of Cryptogamic forms of that period,
+and the familiar statement that they formed the main constituent of the
+Coal-forests still holds good.  The three classes, Ferns (Filicales),
+Horsetails (Equisetales) and Club-mosses (Lycopodiales), under which we now
+group the Vascular Cryptogams, all extend back in geological history as far
+as we have any record of the flora of the land; in the Palaeozoic, however,
+a fourth class, the Sphenophyllales, was present.
+
+As regards the early history of the Ferns, which are of special interest
+from their relation to the Seed-plants, it is impossible to speak quite
+positively, owing to the difficulty of discriminating between true fossil
+Ferns and the Pteridosperms which so closely simulated them.  The
+difficulty especially affects the question of the position of Marattiaceous
+Ferns in the Palaeozoic Floras.  This family, now so restricted, was until
+recently believed to have been one of the most important groups of
+Palaeozoic plants, especially during later Carboniferous and Permian times.
+Evidence both from anatomy and from sporangial characters appeared to
+establish this conclusion.  Of late, however, doubts have arisen, owing to
+the discovery that some supposed members of the Marattiaceae bore seeds,
+and that a form of fructification previously referred to that family
+(Crossotheca) was really the pollen-bearing apparatus of a Pteridosperm
+(Lyginodendron).  The question presents much difficulty; though it seems
+certain that our ideas of the extent of the family in Palaeozoic times will
+have to be restricted, there is still a decided balance of evidence in
+favour of the view that a considerable body of Marattiaceous Ferns actually
+existed.  The plants in question were of large size (often arborescent) and
+highly organised--they represent, in fact, one of the highest developments
+of the Fern-stock, rather than a primitive type of the class.
+
+There was, however, in the Palaeozoic period, a considerable group of
+comparatively simple Ferns (for which Arber has proposed the collective
+name Primofilices); the best known of these are referred to the family
+Botryopterideae, consisting of plants of small or moderate dimensions,
+with, on the whole, a simple anatomical structure, in certain cases
+actually simpler than that of any recent Ferns.  On the other hand the
+sporangia of these plants were usually borne on special fertile fronds, a
+mark of rather high differentiation.  This group goes back to the Devonian
+and includes some of the earliest types of Fern with which we are
+acquainted.  It is probable that the Primofilices (though not the
+particular family Botryopterideae) represent the stock from which the
+various families of modern Ferns, already developed in the Mesozoic period,
+may have sprung.
+
+None of the early Ferns show any clear approach to other classes of
+Vascular Cryptogams; so far as the fossil record affords any evidence,
+Ferns have always been plants with relatively large and usually compound
+leaves.  There is no indication of their derivation from a microphyllous
+ancestry, though, as we shall see, there is some slight evidence for the
+converse hypothesis.  Whatever the origin of the Ferns may have been it is
+hidden in the older rocks.
+
+It has, however, been held that certain other Cryptogamic phyla had a
+common origin with the Ferns.  The Equisetales are at present a well-
+defined group; even in the rich Palaeozoic floras the habit, anatomy and
+reproductive characters usually render the members of this class
+unmistakable, in spite of the great development and stature which they then
+attained.  It is interesting, however, to find that in the oldest known
+representatives of the Equisetales the leaves were highly developed and
+dichotomously divided, thus differing greatly from the mere scale-leaves of
+the recent Horsetails, or even from the simple linear leaves of the later
+Calamites.  The early members of the class, in their forked leaves, and in
+anatomical characters, show an approximation to the Sphenophyllales, which
+are chiefly represented by the large genus Sphenophyllum, ranging through
+the Palaeozoic from the Middle Devonian onwards.  These were plants with
+rather slender, ribbed stems, bearing whorls of wedge-shaped or deeply
+forked leaves, six being the typical number in each whorl.  From their weak
+habit it has been conjectured, with much probability, that they may have
+been climbing plants, like the scrambling Bedstraws of our hedgerows.  The
+anatomy of the stem is simple and root-like; the cones are remarkable for
+the fact that each scale or sporophyll is a double structure, consisting of
+a lower, usually sterile lobe and one or more upper lobes bearing the
+sporangia; in one species both parts of the sporophyll were fertile. 
+Sphenophyllum was evidently much specialised; the only other known genus is
+based on an isolated cone, Cheirostrobus, of Lower Carboniferous age, with
+an extraordinarily complex structure.  In this genus especially, but also
+in the entire group, there is an evident relation to the Equisetales; hence
+it is of great interest that Nathorst has described, from the Devonian of
+Bear Island in the Arctic regions, a new genus Pseudobornia, consisting of
+large plants, remarkable for their highly compound leaves which, when found
+detached, were taken for the fronds of a Fern.  The whorled arrangement of
+the leaves, and the habit of the plant, suggest affinities either with the
+Equisetales or the Sphenophyllales; Nathorst makes the genus the type of a
+new class, the Pseudoborniales.  (A.G. Nathorst, "Zur Oberdevonischen Flora
+der Baren-Insel", "Kongl. Svenska Vetenskaps-Akademiens Handlingar" Bd. 36,
+No. 3, Stockholm, 1902.)
+
+The available data, though still very fragmentary, certainly suggest that
+both Equisetales and Sphenophyllales may have sprung from a common stock
+having certain fern-like characters.  On the other hand the Sphenophylls,
+and especially the peculiar genus Cheirostrobus, have in their anatomy a
+good deal in common with the Lycopods, and of late years they have been
+regarded as the derivatives of a stock common to that class and the
+Equisetales.  At any rate the characters of the Sphenophyllales and of the
+new group Pseudoborniales suggest the existence, at a very early period, of
+a synthetic race of plants, combining the characters of various phyla of
+the Vascular Cryptogams.  It may further be mentioned that the Psilotaceae,
+an isolated epiphytic family hitherto referred to the Lycopods, have been
+regarded by several recent authors as the last survivors of the
+Sphenophyllales, which they resemble both in their anatomy and in the
+position of their sporangia.
+
+The Lycopods, so far as their early history is known, are remarkable rather
+for their high development in Palaeozoic times than for any indications of
+a more primitive ancestry.  In the recent Flora, two of the four living
+genera (Excluding Psilotaceae.) (Selaginella and Isoetes) have spores of
+two kinds, while the other two (Lycopodium and Phylloglossum) are
+homosporous.  Curiously enough, no certain instance of a homosporous
+Palaeozoic Lycopod has yet been discovered, though well-preserved
+fructifications are numerous.  Wherever the facts have been definitely
+ascertained, we find two kinds of spore, differentiated quite as sharply as
+in any living members of the group.  Some of the Palaeozoic Lycopods, in
+fact, went further, and produced bodies of the nature of seeds, some of
+which were actually regarded, for many years, as the seeds of Gymnosperms. 
+This specially advanced form of fructification goes back at least as far as
+the Lower Carboniferous, while the oldest known genus of Lycopods,
+Bothrodendron, which is found in the Devonian, though not seed-bearing, was
+typically heterosporous, if we may judge from the Coal-measure species.  No
+doubt homosporous Lycopods existed, but the great prevalence of the higher
+mode of reproduction in days which to us appear ancient, shows how long a
+course of evolution must have already been passed through before the oldest
+known members of the group came into being.  The other characters of the
+Palaeozoic Lycopods tell the same tale; most of them attained the stature
+of trees, with a corresponding elaboration of anatomical structure, and
+even the herbaceous forms show no special simplicity.  It appears from
+recent work that herbaceous Lycopods, indistinguishable from our recent
+Selaginellas, already existed in the time of the Coal-measures, while one
+herbaceous form (Miadesmia) is known to have borne seeds.
+
+The utmost that can be said for primitiveness of character in Palaeozoic
+Lycopods is that the anatomy of the stem, in its primary ground-plan, as
+distinguished from its secondary growth, was simpler than that of most
+Lycopodiums and Selaginellas at the present day.  There are also some
+peculiarities in the underground organs (Stigmaria) which suggest the
+possibility of a somewhat imperfect differentiation between root and stem,
+but precisely parallel difficulties are met with in the case of the living
+Selaginellas, and in some degree in species of Lycopodium.
+
+In spite of their high development in past ages the Lycopods, recent and
+fossil, constitute, on the whole, a homogeneous group, and there is little
+at present to connect them with other phyla.  Anatomically some relation to
+the Sphenophylls is indicated, and perhaps the recent Psilotaceae give some
+support to this connection, for while their nearest alliance appears to be
+with the Sphenophylls, they approach the Lycopods in anatomy, habit, and
+mode of branching.
+
+The typically microphyllous character of the Lycopods, and the simple
+relation between sporangium and sporophyll which obtains throughout the
+class, have led various botanists to regard them as the most primitive
+phylum of the Vascular Cryptogams.  There is nothing in the fossil record
+to disprove this view, but neither is there anything to support it, for
+this class so far as we know is no more ancient than the megaphyllous
+Cryptogams, and its earliest representatives show no special simplicity. 
+If the indications of affinity with Sphenophylls are of any value the
+Lycopods are open to suspicion of reduction from a megaphyllous ancestry,
+but there is no direct palaeontological evidence for such a history.
+
+The general conclusions to which we are led by a consideration of the
+fossil record of the Vascular Cryptogams are still very hypothetical, but
+may be provisionally stated as follows:
+
+The Ferns go back to the earliest known period.  In Mesozoic times
+practically all the existing families had appeared; in the Palaeozoic the
+class was less extensive than formerly believed, a majority of the supposed
+Ferns of that age having proved to be seed-bearing plants.  The oldest
+authentic representatives of the Ferns were megaphyllous plants, broadly
+speaking, of the same type as those of later epochs, though differing much
+in detail.  As far back as the record extends they show no sign of becoming
+merged with other phyla in any synthetic group.
+
+The Equisetales likewise have a long history, and manifestly attained their
+greatest development in Palaeozoic times.  Their oldest forms show an
+approach to the extinct class Sphenophyllales, which connects them to some
+extent, by anatomical characters, with the Lycopods.  At the same time the
+oldest Equisetales show a somewhat megaphyllous character, which was more
+marked in the Devonian Pseudoborniales.  Some remote affinity with the
+Ferns (which has also been upheld on other grounds) may thus be indicated.
+It is possible that in the Sphenophyllales we may have the much-modified
+representatives of a very ancient synthetic group.
+
+The Lycopods likewise attained their maximum in the Palaeozoic, and show,
+on the whole, a greater elaboration of structure in their early forms than
+at any later period, while at the same time maintaining a considerable
+degree of uniformity in morphological characters throughout their history.
+The Sphenophyllales are the only other class with which they show any
+relation; if such a connection existed, the common point of origin must lie
+exceedingly far back.
+
+The fossil record, as at present known, cannot, in the nature of things,
+throw any direct light on what is perhaps the most disputed question in the
+morphology of plants--the origin of the alternating generations of the
+higher Cryptogams and the Spermophyta.  At the earliest period to which
+terrestrial plants have been traced back all the groups of Vascular
+Cryptogams were in a highly advanced stage of evolution, while innumerable
+Seed-plants--presumably the descendants of Cryptogamic ancestors--were
+already flourishing.  On the other hand we know practically nothing of
+Palaeozoic Bryophyta, and the evidence even for their existence at that
+period cannot be termed conclusive.  While there are thus no
+palaeontological grounds for the hypothesis that the Vascular plants came
+of a Bryophytic stock, the question of their actual origin remains
+unsolved.
+
+III.  NATURAL SELECTION.
+
+Hitherto we have considered the palaeontological record of plants in
+relation to Evolution.  The question remains, whether the record throws any
+light on the theory of which Darwin and Wallace were the authors--that of
+Natural Selection.  The subject is clearly one which must be investigated
+by other methods than those of the palaeontologist; still there are certain
+important points involved, on which the palaeontological record appears to
+bear.
+
+One of these points is the supposed distinction between morphological and
+adaptive characters, on which Nageli, in particular, laid so much stress. 
+The question is a difficult one; it was discussed by Darwin ("Origin of
+Species" (6th edition), pages 170-176.), who, while showing that the
+apparent distinction is in part to be explained by our imperfect knowledge
+of function, recognised the existence of important morphological characters
+which are not adaptations.  The following passage expresses his conclusion.
+"Thus, as I am inclined to believe, morphological differences, which we
+consider as important--such as the arrangement of the leaves, the divisions
+of the flower or of the ovarium, the position of the ovules, etc.--first
+appeared in many cases as fluctuating variations, which sooner or later
+became constant through the nature of the organism and of the surrounding
+conditions, as well as through the inter-crossing of distinct individuals,
+but not through natural selection; for as these morphological characters do
+not affect the welfare of the species, any slight deviations in them could
+not have been governed or accumulated through this latter agency."  (Ibid.
+page 176.)
+
+This is a sufficiently liberal concession; Nageli, however, went much
+further when he said:  "I do not know among plants a morphological
+modification which can be explained on utilitarian principles."  (See "More
+Letters", Vol. II. page 375 (footnote).)  If this were true the field of
+Natural Selection would be so seriously restricted, as to leave the theory
+only a very limited importance.
+
+It can be shown, as the writer believes, that many typical "morphological
+characters," on which the distinction between great classes of plants is
+based, were adaptive in origin, and even that their constancy is due to
+their functional importance.  Only one or two cases will be mentioned,
+where the fossil evidence affects the question.
+
+The pollen-tube is one of the most important morphological characters of
+the Spermophyta as now existing--in fact the name Siphonogama is used by
+Engler in his classification, as expressing a peculiarly constant character
+of the Seed-plants.  Yet the pollen-tube is a manifest adaptation,
+following on the adoption of the seed-habit, and serving first to bring the
+spermatozoids with greater precision to their goal, and ultimately to
+relieve them of the necessity for independent movement.  The pollen-tube is
+constant because it has proved to be indispensable.
+
+In the Palaeozoic Seed-plants there are a number of instances in which the
+pollen-grains, contained in the pollen-chamber of a seed, are so
+beautifully preserved that the presence of a group of cells within the
+grain can be demonstrated; sometimes we can even see how the cell-walls
+broke down to emit the sperms, and quite lately it is said that the sperms
+themselves have been recognised.  (F.W. Oliver, "On Physostoma elegans, an
+archaic type of seed from the Palaeozoic Rocks", "Annals of Botany",
+January, 1909.  See also the earlier papers there cited.)  In no case,
+however, is there as yet any satisfactory evidence for the formation of a
+pollen-tube; it is probable that in these early Seed-plants the pollen-
+grains remained at about the evolutionary level of the microspores in
+Pilularia or Selaginella, and discharged their spermatozoids directly,
+leaving them to find their own way to the female cells.  It thus appears
+that there were once Spermophyta without pollen-tubes.  The pollen-tube
+method ultimately prevailed, becoming a constant "morphological character,"
+for no other reason than because, under the new conditions, it provided a
+more perfect mechanism for the accomplishment of the act of fertilisation. 
+We have still, in the Cycads and Ginkgo, the transitional case, where the
+tube remains short, serves mainly as an anchor and water-reservoir, but yet
+is able, by its slight growth, to give the spermatozoids a "lift" in the
+right direction.  In other Seed-plants the sperms are mere passengers,
+carried all the way by the pollen-tube; this fact has alone rendered the
+Angiospermous method of fertilisation through a stigma possible.
+
+We may next take the seed itself--the very type of a morphological
+character.  Our fossil record does not go far enough back to tell us the
+origin of the seed in the Cycadophyta and Pteridosperms (the main line of
+its development) but some interesting sidelights may be obtained from the
+Lycopod phylum.  In two Palaeozoic genera, as we have seen, seed-like
+organs are known to have been developed, resembling true seeds in the
+presence of an integument and of a single functional embryo-sac, as well as
+in some other points.  We will call these organs "seeds" for the sake of
+shortness.  In one genus (Lepidocarpon) the seeds were borne on a cone
+indistinguishable from that of the ordinary cryptogamic Lepidodendreae, the
+typical Lycopods of the period, while the seed itself retained much of the
+detailed structure of the sporangium of that family.  In the second genus,
+Miadesmia, the seed-bearing plant was herbaceous, and much like a recent
+Selaginella.  (See Margaret Benson, "Miadesmia membranacea, a new
+Palaeozoic Lycopod with a seed-like structure", "Phil. Trans. Royal Soc.
+Vol. 199, B. 1908.)  The seeds of the two genera are differently
+constructed, and evidently had an independent origin.  Here, then, we have
+seeds arising casually, as it were, at different points among plants which
+otherwise retain all the characters of their cryptogamic fellows; the seed
+is not yet a morphological character of importance.  To suppose that in
+these isolated cases the seed sprang into being in obedience to a Law of
+Advance ("Vervollkommungsprincip"), from which other contemporary Lycopods
+were exempt, involves us in unnecessary mysticism.  On the other hand it is
+not difficult to see how these seeds may have arisen, as adaptive
+structures, under the influence of Natural Selection.  The seed-like
+structure afforded protection to the prothallus, and may have enabled the
+embryo to be launched on the world in greater security.  There was further,
+as we may suppose, a gain in certainty of fertilisation.  As the writer has
+pointed out elsewhere, the chances against the necessary association of the
+small male with the large female spores must have been enormously great
+when the cones were borne high up on tall trees.  The same difficulty may
+have existed in the case of the herbaceous Miadesmia, if, as Miss Benson
+conjectures, it was an epiphyte.  One way of solving the problem was for
+pollination to take place while the megaspore was still on the parent
+plant, and this is just what the formation of an ovule or seed was likely
+to secure.
+
+The seeds of the Pteridosperms, unlike those of the Lycopod stock, have not
+yet been found in statu nascendi--in all known cases they were already
+highly developed organs and far removed from the cryptogamic sporangium. 
+But in two respects we find that these seeds, or some of them, had not yet
+realised their possibilities.  In the seed of Lyginodendron and other cases
+the micropyle, or orifice of the integument, was not the passage through
+which the pollen entered; the open neck of the pollen-chamber protruded
+through the micropyle and itself received the pollen.  We have met with an
+analogous case, at a more advanced stage of evolution, in the Bennettiteae,
+where the wall of the gynaecium, though otherwise closed, did not provide a
+stigma to catch the pollen, but allowed the micropyles of the ovules to
+protrude and receive the pollen in the old gymnospermous fashion.  The
+integument in the one case and the pistil in the other had not yet assumed
+all the functions to which the organ ultimately became adapted.  Again, no
+Palaeozoic seed has yet been found to contain an embryo, though the
+preservation is often good enough for it to have been recognised if
+present.  It is probable that the nursing of the embryo had not yet come to
+be one of the functions of the seed, and that the whole embryonic
+development was relegated to the germination stage.
+
+In these two points, the reception of the pollen by the micropyle and the
+nursing of the embryo, it appears that many Palaeozoic seeds were
+imperfect, as compared with the typical seeds of later times.  As evolution
+went on, one function was superadded on another, and it appears impossible
+to resist the conclusion that the whole differentiation of the seed was a
+process of adaptation, and consequently governed by Natural Selection, just
+as much as the specialisation of the rostellum in an Orchid, or of the
+pappus in a Composite.
+
+Did space allow, other examples might be added.  We may venture to maintain
+that the glimpses which the fossil record allows us into early stages in
+the evolution of organs now of high systematic importance, by no means
+justify the belief in any essential distinction between morphological and
+adaptive characters.
+
+Another point, closely connected with Darwin's theory, on which the fossil
+history of plants has been supposed to have some bearing, is the question
+of Mutation, as opposed to indefinite variation.  Arber and Parkin, in
+their interesting memoir on the Origin of Angiosperms, have suggested
+calling in Mutation to explain the apparently sudden transition from the
+cycadean to the angiospermous type of foliage, in late Mesozoic times,
+though they express themselves with much caution, and point out "a distinct
+danger that Mutation may become the last resort of the phylogenetically
+destitute"!
+
+The distinguished French palaeobotanists, Grand'Eury (C. Grand'Eury, "Sur
+les mutations de quelques Plantes fossiles du Terrain houiller".  "Comptes
+Rendus", CXLII. page 25, 1906.) and Zeiller (R. Zeiller "Les Vegetaux
+fossiles et leurs Enchainements", "Revue du Mois", III. February, 1907.),
+are of opinion, to quote the words of the latter writer, that the facts of
+fossil Botany are in agreement with the sudden appearance of new forms,
+differing by marked characters from those that have given them birth; he
+adds that these results give more amplitude to this idea of Mutation,
+extending it to groups of a higher order, and even revealing the existence
+of discontinuous series between the successive terms of which we yet
+recognise bonds of filiation.  (Loc. cit. page 23.)
+
+If Zeiller's opinion should be confirmed, it would no doubt be a serious
+blow to the Darwinian theory.  As Darwin said:  "Under a scientific point
+of view, and as leading to further investigation, but little advantage is
+gained by believing that new forms are suddenly developed in an
+inexplicable manner from old and widely different forms, over the old
+belief in the creation of species from the dust of the earth."  ("Origin of
+Species", page 424.)
+
+It most however be pointed out, that such mutations as Zeiller, and to some
+extent Arber and Parkin, appear to have in view, bridging the gulf between
+different Orders and Classes, bear no relation to any mutations which have
+been actually observed, such as the comparatively small changes, of sub-
+specific value, described by De Vries in the type-case of Oenothera
+Lamarckiana.  The results of palaeobotanical research have undoubtedly
+tended to fill up gaps in the Natural System of plants--that many such gaps
+still persist is not surprising; their presence may well serve as an
+incentive to further research but does not, as it seems to the writer,
+justify the assumption of changes in the past, wholly without analogy among
+living organisms.
+
+As regards the succession of species, there are no greater authorities than
+Grand'Eury and Zeiller, and great weight must be attached to their opinion
+that the evidence from continuous deposits favours a somewhat sudden change
+from one specific form to another.  At the same time it will be well to
+bear in mind that the subject of the "absence of numerous intermediate
+varieties in any single formation" was fully discussed by Darwin.  ("Origin
+of Species", pages 275-282, and page 312.); the explanation which he gave
+may go a long way to account for the facts which recent writers have
+regarded as favouring the theory of saltatory mutation.
+
+The rapid sketch given in the present essay can do no more than call
+attention to a few salient points, in which the palaeontological records of
+plants has an evident bearing on the Darwinian theory.  At the present day
+the whole subject of palaeobotany is a study in evolution, and derives its
+chief inspiration from the ideas of Darwin and Wallace.  In return it
+contributes something to the verification of their teaching; the recent
+progress of the subject, in spite of the immense difficulties which still
+remain, has added fresh force to Darwin's statement that "the great leading
+facts in palaeontology agree admirably with the theory of descent with
+modification through variation and natural selection."  (Ibid. page 313.)
+
+
+XIII.  THE INFLUENCE OF ENVIRONMENT ON THE FORMS OF PLANTS.
+
+By GEORG KLEBS, PH.D.
+Professor of Botany in the University of Heidelberg.
+
+The dependence of plants on their environment became the object of
+scientific research when the phenomena of life were first investigated and
+physiology took its place as a special branch of science.  This occurred in
+the course of the eighteenth century as the result of the pioneer work of
+Hales, Duhamel, Ingenhousz, Senebier and others.  In the nineteenth
+century, particularly in the second half, physiology experienced an
+unprecedented development in that it began to concern itself with the
+experimental study of nutrition and growth, and with the phenomena
+associated with stimulus and movement; on the other hand, physiology
+neglected phenomena connected with the production of form, a department of
+knowledge which was the province of morphology, a purely descriptive
+science.  It was in the middle of the last century that the growth of
+comparative morphology and the study of phases of development reached their
+highest point.
+
+The forms of plants appeared to be the expression of their inscrutable
+inner nature; the stages passed through in the development of the
+individual were regarded as the outcome of purely internal and hidden laws.
+The feasibility of experimental inquiry seemed therefore remote. 
+Meanwhile, the recognition of the great importance of such a causal
+morphology emerged from the researches of the physiologists of that time,
+more especially from those of Hofmeister (Hofmeister, "Allgemeine
+Morphologie", Leipzig, 1868, page 579.), and afterwards from the work of
+Sachs.  (Sachs, "Stoff und Form der Pflanzenorgane", Vol. I. 1880; Vol. II.
+1882.  "Gesammelte Abhandlungen uber Pflanzen-Physiologie", II. Leipzig,
+1893.)  Hofmeister, in speaking of this line of inquiry, described it as
+"the most pressing and immediate aim of the investigator to discover to
+what extent external forces acting on the organism are of importance in
+determining its form."  This advance was the outcome of the influence of
+that potent force in biology which was created by Darwin's "Origin of
+Species" (1859).
+
+The significance of the splendid conception of the transformation of
+species was first recognised and discussed by Lamarck (1809); as an
+explanation of transformation he at once seized upon the idea--an
+intelligible view--that the external world is the determining factor. 
+Lamarck (Lamarck, "Philosophie zoologique", pages 223-227.  Paris, 1809.)
+endeavoured, more especially, to demonstrate from the behaviour of plants
+that changes in environment induce change in form which eventually leads to
+the production of new species.  In the case of animals, Lamarck adopted the
+teleological view that alterations in the environment first lead to
+alterations in the needs of the organisms, which, as the result of a kind
+of conscious effort of will, induce useful modifications and even the
+development of new organs.  His work has not exercised any influence on the
+progress of science:  Darwin himself confessed in regard to Lamarck's work
+--"I got not a fact or idea from it."  ("Life and Letters", Vol. II. page
+215.)
+
+On a mass of incomparably richer and more essential data Darwin based his
+view of the descent of organisms and gained for it general acceptance; as
+an explanation of modification he elaborated the ingeniously conceived
+selection theory.  The question of special interest in this connection,
+namely what is the importance of the influence of the environment, Darwin
+always answered with some hesitation and caution, indeed with a certain
+amount of indecision.
+
+The fundamental principle underlying his theory is that of general
+variability as a whole, the nature and extent of which, especially in
+cultivated organisms, are fully dealt with in his well-known book. 
+(Darwin, "The variation of Animals and Plants under domestication", 2
+vols., edition 1, 1868; edition 2, 1875; popular edition 1905.)  In regard
+to the question as to the cause of variability Darwin adopts a consistently
+mechanical view.  He says:  "These several considerations alone render it
+probable that variability of every kind is directly or indirectly caused by
+changed conditions of life.  Or, to put the case under another point of
+view, if it were possible to expose all the individuals of a species during
+many generations to absolutely uniform conditions of life, there would be
+no variability."  ("The variation of Animals and Plants" (2nd edition),
+Vol. II. page 242.)  Darwin did not draw further conclusions from this
+general principle.
+
+Variations produced in organisms by the environment are distinguished by
+Darwin as "the definite" and "the indefinite."  (Ibid. II. page 260.  See
+also "Origin of Species" (6th edition), page 6.)  The first occur "when all
+or nearly all the offspring of an individual exposed to certain conditions
+during several generations are modified in the same manner."  Indefinite
+variation is much more general and a more important factor in the
+production of new species; as a result of this, single individuals are
+distinguished from one another by "slight" differences, first in one then
+in another character.  There may also occur, though this is very rare, more
+marked modifications, "variations which seem to us in our ignorance to
+arise spontaneously."  ("Origin of Species" (6th edition), page 421.)  The
+selection theory demands the further postulate that such changes, "whether
+extremely slight or strongly marked," are inherited.  Darwin was no nearer
+to an experimental proof of this assumption than to the discovery of the
+actual cause of variability.  It was not until the later years of his life
+that Darwin was occupied with the "perplexing problem...what causes almost
+every cultivated plant to vary" ("Life and Letters", Vol. III. page 342.): 
+he began to make experiments on the influence of the soil, but these were
+soon given up.
+
+In the course of the violent controversy which was the outcome of Darwin's
+work the fundamental principles of his teaching were not advanced by any
+decisive observations.  Among the supporters and opponents, Nageli (Nageli,
+"Theorie der Abstammungslehre", Munich, 1884; cf. Chapter III.) was one of
+the few who sought to obtain proofs by experimental methods.  His extensive
+cultural experiments with alpine Hieracia led him to form the opinion that
+the changes which are induced by an alteration in the food-supply, in
+climate or in habitat, are not inherited and are therefore of no importance
+from the point of view of the production of species.  And yet Nageli did
+attribute an important influence to the external world; he believed that
+adaptations of plants arise as reactions to continuous stimuli, which
+supply a need and are therefore useful.  These opinions, which recall the
+teleological aspect of Lamarckism, are entirely unsupported by proof. 
+While other far-reaching attempts at an explanation of the theory of
+descent were formulated both in Nageli's time and afterwards, some in
+support of, others in opposition to Darwin, the necessity of investigating,
+from different standpoints, the underlying causes, variability and
+heredity, was more and more realised.  To this category belong the
+statistical investigations undertaken by Quetelet and Galton, the
+researches into hybridisation, to which an impetus was given by the re-
+discovery of the Mendelian law of segregation, as also by the culture
+experiments on mutating species following the work of de Vries, and lastly
+the consideration of the question how far variation and heredity are
+governed by external influences.  These latter problems, which are
+concerned in general with the causes of form-production and form-
+modification, may be treated in a short summary which falls under two
+heads, one having reference to the conditions of form-production in single
+species, the other being concerned with the conditions governing the
+transformation of species.
+
+I. THE INFLUENCE OF EXTERNAL CONDITIONS ON FORM-PRODUCTION IN SINGLE
+SPECIES.
+
+The members of plants, which we express by the terms stem, leaf, flower,
+etc. are capable of modification within certain limits; since Lamarck's
+time this power of modification has been brought more or less into relation
+with the environment.  We are concerned not only with the question of
+experimental demonstration of this relationship, but, more generally, with
+an examination of the origin of forms, the sequences of stages in
+development that are governed by recognisable causes.  We have to consider
+the general problem; to study the conditions of all typical as well as of
+atypic forms, in other words, to found a physiology of form.
+
+If we survey the endless variety of plant-forms and consider the highly
+complex and still little known processes in the interior of cells, and if
+we remember that the whole of this branch of investigation came into
+existence only a few decades ago, we are able to grasp the fact that a
+satisfactory explanation of the factors determining form cannot be
+discovered all at once.  The goal is still far away.  We are not concerned
+now with the controversial question, whether, on the whole, the fundamental
+processes in the development of form can be recognised by physiological
+means.  A belief in the possibility of this can in any case do no harm. 
+What we may and must attempt is this--to discover points of attack on one
+side or another, which may enable us by means of experimental methods to
+come into closer touch with these elusive and difficult problems.  While we
+are forced to admit that there is at present much that is insoluble there
+remains an inexhaustible supply of problems capable of solution.
+
+The object of our investigations is the species; but as regards the
+question, what is a species, science of to-day takes up a position
+different from that of Darwin.  For him it was the Linnean species which
+illustrates variation:  we now know, thanks to the work of Jordan, de Bary,
+and particularly to that of de Vries (de Vries, "Die Mutationstheorie",
+Leipzig, 1901, Vol. I. page 33.), that the Linnean species consists of a
+large or small number of entities, elementary species.  In experimental
+investigation it is essential that observations be made on a pure species,
+or, as Johannsen (Johannsen, "Ueber Erblichkeit in Populationen und reinen
+Linien", Jena, 1903.) says, on a pure "line."  What has long been
+recognised as necessary in the investigation of fungi, bacteria and algae
+must also be insisted on in the case of flowering plants; we must start
+with a single individual which is reproduced vegetatively or by strict
+self-fertilisation.  In dioecious plants we must aim at the reproduction of
+brothers and sisters.
+
+We may at the outset take it for granted that a pure species remains the
+same under similar external conditions; it varies as these vary.  IT IS
+CHARACTERISTIC OF A SPECIES THAT IT ALWAYS EXHIBITS A CONSTANT RELATION TO
+A PARTICULAR ENVIRONMENT.  In the case of two different species, e.g. the
+hay and anthrax bacilli or two varieties of Campanula with blue and white
+flowers respectively, a similar environment produces a constant difference. 
+The cause of this is a mystery.
+
+According to the modern standpoint, the living cell is a complex chemico-
+physical system which is regarded as a dynamical system of equilibrium, a
+conception suggested by Herbert Spencer and which has acquired a constantly
+increasing importance in the light of modern developments in physical
+chemistry.  The various chemical compounds, proteids, carbohydrates, fats,
+the whole series of different ferments, etc. occur in the cell in a
+definite physical arrangement.  The two systems of two species must as a
+matter of fact possess a constant difference, which it is necessary to
+define by a special term.  We say, therefore, that the SPECIFIC STRUCTURE
+is different.
+
+By way of illustrating this provisionally, we may assume that the proteids
+of the two species possess a constant chemical difference.  This conception
+of specific structure is specially important in its bearing on a further
+treatment of the subject.  In the original cell, eventually also in every
+cell of a plant, the characters which afterwards become apparent must exist
+somewhere; they are integral parts of the capabilities or potentialities of
+specific structure.  Thus not only the characters which are exhibited under
+ordinary conditions in nature, but also many others which become apparent
+only under special conditions (In this connection I leave out of account,
+as before, the idea of material carriers of heredity which since the
+publication of Darwin's Pangenesis hypothesis has been frequently
+suggested.  See my remarks in "Variationen der Bluten", "Pringsheim's
+Jahrb. Wiss. Bot." 1905, page 298; also Detto, "Biol. Centralbl." 1907,
+page 81, "Die Erklarbarkeit der Ontogenese durch materielle Anlagen".), are
+to be included as such potentialities in cells; the conception of specific
+structure includes the WHOLE OF THE POTENTIALITIES OF A SPECIES; specific
+structure comprises that which we must always assume without being able to
+explain it.
+
+A relatively simple substance, such as oxalate of lime, is known under a
+great number of different crystalline forms belonging to different systems
+(Compare Kohl's work on "Anatomisch-phys. Untersuchungen uber Kalksalze",
+etc. Marburg, 1889.); these may occur as single crystals, concretions or as
+concentric sphaerites.  The power to assume this variety of form is in some
+way inherent in the molecular structure, though we cannot, even in this
+case, explain the necessary connection between structure and crystalline
+form.  These potentialities can only become operative under the influence
+of external conditions; their stimulation into activity depends on the
+degree of concentration of the various solutions, on the nature of the
+particular calcium salt, on the acid or alkaline reactions.  Broadly
+speaking, the plant cell behaves in a similar way.  The manifestation of
+each form, which is inherent as a potentiality in the specific structure,
+is ultimately to be referred to external conditions.
+
+An insight into this connection is, however, rendered exceedingly
+difficult, often quite impossible, because the environment never directly
+calls into action the potentialities.  Its influence is exerted on what we
+may call the inner world of the organism, the importance of which increases
+with the degree of differentiation.  The production of form in every plant
+depends upon processes in the interior of the cells, and the nature of
+these determines which among the possible characters is to be brought to
+light.  In no single case are we acquainted with the internal process
+responsible for the production of a particular form.  All possible factors
+may play a part, such as osmotic pressure, permeability of the protoplasm,
+the degree of concentration of the various chemical substances, etc.; all
+these factors should be included in the category of INTERNAL CONDITIONS. 
+This inner world appears the more hidden from our ken because it is always
+represented by a certain definite state, whether we are dealing with a
+single cell or with a small group of cells.  These have been produced from
+pre-existing cells and they in turn from others; the problem is constantly
+pushed back through a succession of generations until it becomes identified
+with that of the origin of species.
+
+A way, however, is opened for investigation; experience teaches us that
+this inner world is not a constant factor:  on the contrary, it appears to
+be very variable.  The dependence of VARIABLE INTERNAL on VARIABLE EXTERNAL
+conditions gives us the key with which research may open the door.  In the
+lower plants this dependence is at once apparent, each cell is directly
+subject to external influences.  In the higher plants with their different
+organs, these influences were transmitted to cells in course of development
+along exceedingly complex lines.  In the case of the growing-point of a
+bud, which is capable of producing a complete plant, direct influences play
+a much less important part than those exerted through other organs,
+particularly through the roots and leaves, which are essential in
+nutrition.  These correlations, as we may call them, are of the greatest
+importance as aids to an understanding of form-production.  When a bud is
+produced on a particular part of a plant, it undergoes definite internal
+modifications induced by the influence of other organs, the activity of
+which is governed by the environment, and as the result of this it develops
+along a certain direction; it may, for example, become a flower.  The
+particular direction of development is determined before the rudiment is
+differentiated and is exerted so strongly that further development ensues
+without interruption, even though the external conditions vary considerably
+and exert a positively inimical influence:  this produces the impression
+that development proceeds entirely independently of the outer world.  The
+widespread belief that such independence exists is very premature and at
+all events unproven.
+
+The state of the young rudiment is the outcome of previous influences of
+the external world communicated through other organs.  Experiments show
+that in certain cases, if the efficiency of roots and leaves as organs
+concerned with nutrition is interfered with, the production of flowers is
+affected, and their characters, which are normally very constant, undergo
+far-reaching modifications.  To find the right moment at which to make the
+necessary alteration in the environment is indeed difficult and in many
+cases not yet possible.  This is especially the case with fertilised eggs,
+which in a higher degree than buds have acquired, through parental
+influences, an apparently fixed internal organisation, and this seems to
+have pre-determined their development.  It is, however, highly probable
+that it will be possible, by influencing the parents, to alter the internal
+organisation and to switch off development on to other lines.
+
+Having made these general observations I will now cite a few of the many
+facts at our disposal, in order to illustrate the methods and aim of the
+experimental methods of research.  As a matter of convenience I will deal
+separately with modification of development and with modification of single
+organs.
+
+I.  EFFECT OF ENVIRONMENT UPON THE COURSE OF DEVELOPMENT.
+
+Every plant, whether an alga or a flowering plant passes, under natural
+conditions, through a series of developmental stages characteristic of each
+species, and these consist in a regular sequence of definite forms.  It is
+impossible to form an opinion from mere observation and description as to
+what inner changes are essential for the production of the several forms. 
+We must endeavour to influence the inner factors by known external
+conditions in such a way that the individual stages in development are
+separately controlled and the order of their sequence determined at will by
+experimental treatment.  Such control over the course of development may be
+gained with special certainty in the case of the lower organisms.
+
+With these it is practicable to control the principal conditions of
+cultivation and to vary them in various ways.  By this means it has been
+demonstrated that each developmental stage depends upon special external
+conditions, and in cases where our knowledge is sufficient, a particular
+stage may be obtained at will.  In the Green Algae (See Klebs, "Die
+Bedingung der Fortpflanzung...", Jena, 1896; also "Jahrb. fur Wiss. Bot."
+1898 and 1900; "Probleme der Entwickelung, III."  "Biol. Centralbl." 1904,
+page 452.), as in the case of Fungi, we may classify the stages of
+development into purely vegetative growth (growth, cell-division,
+branching), asexual reproduction (formation of zoospores, conidia) and
+sexual processes (formation of male and female sexual organs).  By
+modifying the external conditions it is possible to induce algae or fungi
+(Vaucheria, Saprolegnia) to grow continuously for several years or, in the
+course of a few days, to die after an enormous production of asexual or
+sexual cells.  In some instances even an almost complete stoppage of growth
+may be caused, reproductive cells being scarcely formed before the organism
+is again compelled to resort to reproduction.  Thus the sequence of the
+different stages in development can be modified as we may desire.
+
+The result of a more thorough investigation of the determining conditions
+appears to produce at first sight a confused impression of all sorts of
+possibilities.  Even closely allied species exhibit differences in regard
+to the connection between their development and external conditions.  It is
+especially noteworthy that the same form in development may be produced as
+the result of very different alterations in the environment.  At the same
+time we can undoubtedly detect a certain unity in the multiplicity of the
+individual phenomena.
+
+If we compare the factors essential for the different stages in
+development, we see that the question always resolves itself into one of
+modification of similar conditions common to all life-processes.  We should
+rather have inferred that there exist specific external stimuli for each
+developmental stage, for instance, certain chemical agencies.  Experiments
+hitherto made support the conclusion that QUANTITATIVE alterations in the
+general conditions of life produce different types of development.  An alga
+or a fungus grows so long as all the conditions of nutrition remain at a
+certain optimum for growth.  In order to bring about asexual reproduction,
+e.g. the formation of zoospores, it is sometimes necessary to increase the
+degree of intensity of external factors; sometimes, on the other hand,
+these must be reduced in intensity.  In the case of many algae a decrease
+in light-intensity or in the amount of salts in the culture solution, or in
+the temperature, induces asexual reproduction, while in others, on the
+contrary, an increase in regard to each of these factors is required to
+produce the same result.  This holds good for the quantitative variations
+which induce sexual reproduction in algae.  The controlling factor is found
+to be a reduction in the supply of nutritive salts and the exposure of the
+plants to prolonged illumination or, better still, an increase in the
+intensity of the light, the efficiency of illumination depending on the
+consequent formation of organic substances such as carbohydrates.
+
+The quantitative alterations of external conditions may be spoken of as
+releasing stimuli.  They produce, in the complex equilibrium of the cell,
+quantitative modifications in the arrangement and distribution of mass, by
+means of which other chemical processes are at once set in motion, and
+finally a new condition of equilibrium is attained.  But the commonly
+expressed view that the environment can as a rule act only as a releasing
+agent is incorrect, because it overlooks an essential point.  The power of
+a cell to receive stimuli is only acquired as the result of previous
+nutrition, which has produced a definite condition of concentration of
+different substances.  Quantities are in this case the determining factors. 
+The distribution of quantities is especially important in the sexual
+reproduction of algae, for which a vigorous production of the materials
+formed during carbon-assimilation appears to be essential.
+
+In the Flowering plants, on the other hand, for reasons already mentioned,
+the whole problem is more complicated.  Investigations on changes in the
+course of development of fertilised eggs have hitherto been unsuccessful;
+the difficulty of influencing egg-cells deeply immersed in tissue
+constitutes a serious obstacle.  Other parts of plants are, however,
+convenient objects of experiment; e.g. the growing apices of buds which
+serve as cuttings for reproductive purposes, or buds on tubers, runners,
+rhizomes, etc.  A growing apex consists of cells capable of division in
+which, as in egg-cells, a complete series of latent possibilities of
+development is embodied.  Which of these possibilities becomes effective
+depends upon the action of the outer world transmitted by organs concerned
+with nutrition.
+
+Of the different stages which a flowering plant passes through in the
+course of its development we will deal only with one in order to show that,
+in spite of its great complexity, the problem is, in essentials, equally
+open to attack in the higher plants and in the simplest organisms.  The
+most important stage in the life of a flowering plant is the transition
+from purely vegetative growth to sexual reproduction--that is, the
+production of flowers.  In certain cases it can be demonstrated that there
+is no internal cause, dependent simply on the specific structure, which
+compels a plant to produce its flowers after a definite period of
+vegetative growth.  (Klebs, "Willkurliche Entwickelungsanderungen", Jena
+1903; see also "Probleme der Entwickelung", I. II.  "Centralbl." 1904.)
+
+One extreme case, that of exceptionally early flowering, has been observed
+in nature and more often in cultivation.  A number of plants under certain
+conditions are able to flower soon after germination.  (Cf. numerous
+records of this kind by Diels, "Jugendformen und Bluten", Berlin, 1906.) 
+This shortening of the period of development is exhibited in the most
+striking form in trees, as in the oak (Mobius, "Beitrage zur Lehre von der
+Fortpflanzung", Jena, 1897, page 89.), flowering seedlings of which have
+been observed from one to three years old, whereas normally the tree does
+not flower until it is sixty or eighty years old.
+
+Another extreme case is represented by prolonged vegetative growth leading
+to the complete suppression of flower-production.  This result may be
+obtained with several plants, such as Glechoma, the sugar beet, Digitalis,
+and others, if they are kept during the winter in a warm, damp atmosphere,
+and in rich soil; in the following spring or summer they fail to flower. 
+(Klebs, "Willkurliche Aenderungen", etc. Jena, 1903, page 130.) 
+Theoretically, however, experiments are of greater importance in which the
+production of flowers is inhibited by very favourable conditions of
+nutrition (Klebs, "Ueber kunstliche Metamorphosen", Stuttgart, 1906, page
+115 ("Abh. Naturf. Ges. Halle", XXV.) occurring at the normal flowering
+period.  Even in the case of plants of Sempervivum several years old,
+which, as is shown by control experiments on precisely similar plants, are
+on the point of flowering, flowering is rendered impossible if they are
+forced to very vigorous growth by an abundant supply of water and salts in
+the spring.  Flowering, however, occurs, if such plants are cultivated in
+relatively dry sandy soil and in the presence of strong light.  Careful
+researches into the conditions of growth have led, in the cases
+Sempervivum, to the following results:  (1)  With a strong light and
+vigorous carbon-assimilation a considerably increased supply of water and
+nutritive salts produces active vegetative growth.  (2)  With a vigorous
+carbon-assimilation in strong light, and a decrease in the supply of water
+and salts active flower-production is induced.  (3)  If an average supply
+of water and salts is given both processes are possible; the intensity of
+carbon-assimilation determines which of the two is manifested.  A
+diminution in the production of organic substances, particularly of
+carbohydrates, induces vegetative growth.  This can be effected by culture
+in feeble light or in light deprived of the yellow-red rays:  on the other
+hand, flower-production follows an increase in light-intensity.  These
+results are essentially in agreement with well-known observations on
+cultivated plants, according to which, the application of much moisture,
+after a plentiful supply of manure composed of inorganic salts, hinders the
+flower-production of many vegetables, while a decrease in the supply of
+water and salts favours flowering.
+
+ii.  INFLUENCE OF THE ENVIRONMENT ON THE FORM OF SINGLE ORGANS.  (A
+considerable number of observations bearing on this question are given by
+Goebel in his "Experimentelle Morphologie der Pflanzen", Leipzig, 1908.  It
+is not possible to deal here with the alteration in anatomical structure;
+cf. Kuster, "Pathologische Pflanzenanatomie", Jena, 1903.)
+
+If we look closely into the development of a flowering plant, we notice
+that in a given species differently formed organs occur in definite
+positions.  In a potato plant colourless runners are formed from the base
+of the main stem which grow underground and produce tubers at their tips: 
+from a higher level foliage shoots arise nearer the apex.  External
+appearances suggest that both the place of origin and the form of these
+organs were predetermined in the egg-cell or in the tuber.  But it was
+shown experimentally by the well-known investigator Knight (Knight,
+"Selection from the Physiological and Horticultural Papers", London, 1841.)
+that tubers may be developed on the aerial stem in place of foliage shoots. 
+These observations were considerably extended by Vochting.  (Vochting,
+"Ueber die Bildung der Knollen", Cassel, 1887; see also "Bot. Zeit." 1902,
+87.)  In one kind of potato, germinating tubers were induced to form
+foliage shoots under the influence of a higher temperature; at a lower
+temperature they formed tuber-bearing shoots.  Many other examples of the
+conversion of foliage-shoots into runners and rhizomes, or vice versa, have
+been described by Goebel and others.  As in the asexual reproduction of
+algae quantitative alteration in the amount of moisture, light,
+temperature, etc. determines whether this or that form of shoot is
+produced.  If the primordia of these organs are exposed to altered
+conditions of nutrition at a sufficiently early stage a complete
+substitution of one organ for another is effected.  If the rudiment has
+reached a certain stage in development before it is exposed to these
+influences, extraordinary intermediate forms are obtained, bearing the
+characters of both organs.
+
+The study of regeneration following injury is of greater importance as
+regards the problem of the development and place of origin of organs. 
+(Reference may be made to the full summary of results given by Goebel in
+his "Experimentelle Morphologie", Leipzig and Berlin, 1908, Section IV.) 
+Only in relatively very rare cases is there a complete re-formation of the
+injured organ itself, as e.g. in the growing-apex.  Much more commonly
+injury leads to the development of complementary formations, it may be the
+rejuvenescence of a hitherto dormant rudiment, or it may be the formation
+of such ab initio.  In all organs, stems, roots, leaves, as well as
+inflorescences, this kind of regeneration, which occurs in a great variety
+of ways according to the species, may be observed on detached pieces of the
+plant.  Cases are also known, such, for example, as the leaves of many
+plants which readily form roots but not shoots, where a complete
+regeneration does not occur.
+
+The widely spread power of reacting to wounding affords a very valuable
+means of inducing a fresh development of buds and roots on places where
+they do not occur in normal circumstances.  Injury creates special
+conditions, but little is known as yet in regard to alterations directly
+produced in this way.  Where the injury consists in the separation of an
+organ from its normal connections, the factors concerned are more
+comprehensible.  A detached leaf, e.g., is at once cut off from a supply of
+water and salts, and is deprived of the means of getting rid of organic
+substances which it produces; the result is a considerable alteration in
+the degree of concentration.  No experimental investigation on these lines
+has yet been made.  Our ignorance has often led to the view that we are
+dealing with a force whose specific quality is the restitution of the parts
+lost by operation; the proof, therefore, that in certain cases a similar
+production of new roots or buds may be induced without previous injury and
+simply by a change in external conditions assumes an importance.  (Klebs,
+"Willkurliche Entwickelung", page 100; also, "Probleme der Entwickelung",
+"Biol. Centralbl." 1904, page 610.)
+
+A specially striking phenomenon of regeneration, exhibited also by
+uninjured plants, is afforded by polarity, which was discovered by
+Vochting.  (See the classic work of Vochting, "Ueber Organbildung im
+Pflanzenreich", I. Bonn, 1888; also "Bot. Zeit. 1906, page 101; cf. Goebel,
+"Experimentelle Morphologie", Leipzig and Berlin, 1908, Section V,
+Polaritat.)  It is found, for example, that roots are formed from the base
+of a detached piece of stem and shoots from the apex.  Within the limits of
+this essay it is impossible to go into this difficult question; it is,
+however, important from the point of view of our general survey to
+emphasise the fact that the physiological distinctions between base and
+apex of pieces of stem are only of a quantitative kind, that is, they
+consist in the inhibition of certain phenomena or in favouring them.  As a
+matter of fact roots may be produced from the apices of willows and
+cuttings of other plants; the distinction is thus obliterated under the
+influence of environment.  The fixed polarity of cuttings from full grown
+stems cannot be destroyed; it is the expression of previous development. 
+Vochting speaks of polarity as a fixed inherited character.  This is an
+unconvincing conclusion, as nothing can be deduced from our present
+knowledge as to the causes which led up to polarity.  We know that the
+fertilised egg, like the embryo, is fixed at one end by which it hangs
+freely in the embryo-sac and afterwards in the endosperm.  From the first,
+therefore, the two ends have different natures, and these are revealed in
+the differentiation into root-apex and stem-apex.  A definite direction in
+the flow of food-substances is correlated with this arrangement, and this
+eventually leads to a polarity in the tissues.  This view requires
+experimental proof, which in the case of the egg-cells of flowering plants
+hardly appears possible; but it derives considerable support from the fact
+that in herbaceous plants, e.g. Sempervivum (Klebs, "Variationen der
+Bluten", "Jahrb. Wiss. Bot." 1905, page 260.), rosettes or flower-shoots
+are formed in response to external conditions at the base, in the middle,
+or at the apex of the stem, so that polarity as it occurs under normal
+conditions cannot be the result of unalterable hereditary factors.  On the
+other hand, the lower plants should furnish decisive evidence on this
+question, and the experiments of Stahl, Winkler, Kniep, and others indicate
+the right method of attacking the problem.
+
+The relation of leaf-form to environment has often been investigated and is
+well known.  The leaves of bog and water plants (Cf.Goebel, loc. cit.
+chapter II.; also Gluck, "Untersuchungen uber Wasser- und Sumpfgewachse",
+Jena, Vols. I.-II. 1905-06.) afford the most striking examples of
+modifications:  according as they are grown in water, moist or dry air, the
+form of the species characteristic of the particular habitat is produced,
+since the stems are also modified.  To the same group of phenomena belongs
+the modification of the forms of leaves and stems in plants on
+transplantation from the plains to the mountains (Bonnier, "Recherches sur
+l'Anatomie experimentale des Vegetaux", Corbeil, 1895.) or vice versa. 
+Such variations are by no means isolated examples.  All plants exhibit a
+definite alteration in form as the result of prolonged cultivation in moist
+or dry air, in strong or feeble light, or in darkness, or in salt solutions
+of different composition and strength.
+
+Every individual which is exposed to definite combinations of external
+factors exhibits eventually the same type of modification.  This is the
+type of variation which Darwin termed "definite."  It is easy to realise
+that indefinite or fluctuating variations belong essentially to the same
+class of phenomena; both are reactions to changes in environment.  In the
+production of individual variations two different influences undoubtedly
+cooperate.  One set of variations is caused by different external
+conditions, during the production, either of sexual cells or of vegetative
+primordia; another set is the result of varying external conditions during
+the development of the embryo into an adult plant.  The two sets of
+influences cannot as yet be sharply differentiated.  If, for purposes of
+vegetative reproduction, we select pieces of the same parent-plant of a
+pure species, the second type of variation predominates.  Individual
+fluctuations depend essentially in such cases on small variations in
+environment during development.
+
+These relations must be borne in mind if we wish to understand the results
+of statistical methods.  Since the work of Quetelet, Galton, and others the
+statistical examination of individual differences in animals and plants has
+become a special science, which is primarily based on the consideration
+that the application of the theory of probability renders possible
+mathematical statement and control of the results.  The facts show that any
+character, size of leaf, length of stem, the number of members in a flower,
+etc. do not vary haphazard but in a very regular manner.  In most cases it
+is found that there is a value which occurs most commonly, the average or
+medium value, from which the larger and smaller deviations, the so-called
+plus and minus variations fall away in a continuous series and end in a
+limiting value.  In the simpler cases a falling off occurs equally on both
+sides of the curve; the curve constructed from such data agrees very
+closely with the Gaussian curve of error.  In more complicated cases
+irregular curves of different kinds are obtained which may be calculated on
+certain suppositions.
+
+The regular fluctuations about a mean according to the rule of probability
+is often attributed to some law underlying variability.  (de Vries,
+"Mutationstheorie", Vol. I. page 35, Leipzig, 1901.)  But there is no such
+law which compels a plant to vary in a particular manner.  Every
+experimental investigation shows, as we have already remarked, that the
+fluctuation of characters depends on fluctuation in the external factors. 
+The applicability of the method of probability follows from the fact that
+the numerous individuals of a species are influenced by a limited number of
+variable conditions.  (Klebs, "Willkurl. Ent." Jena, 1903, page 141.)  As
+each of these conditions includes within certain limits all possible values
+and exhibits all possible combinations, it follows that, according to the
+rules of probability, there must be a mean value, about which the larger
+and smaller deviations are distributed.  Any character will be found to
+have the mean value which corresponds with that combination of determining
+factors which occurs most frequently.  Deviations towards plus and minus
+values will be correspondingly produced by rarer conditions.
+
+A conclusion of fundamental importance may be drawn from this conception,
+which is, to a certain extent, supported by experimental investigation. 
+(Klebs, "Studien uber Variation", "Arch. fur Entw." 1907.)  There is no
+normal curve for a particular CHARACTER, there is only a curve for the
+varying combinations of conditions occurring in nature or under
+cultivation.  Under other conditions entirely different curves may be
+obtained with other variants as a mean value.  If, for example, under
+ordinary conditions the number 10 is the most frequent variant for the
+stamens of Sedum spectabile, in special circumstances (red light) this is
+replaced by the number 5.  The more accurately we know the conditions for a
+particular form or number, and are able to reproduce it by experiment, the
+nearer we are to achieving our aim of rendering a particular variation
+impossible or of making it dominant.
+
+In addition to the individual variations of a species, more pronounced
+fluctuations occur relatively rarely and sporadically which are spoken of
+as "single variations," or if specially striking as abnormalities or
+monstrosities.  These forms have long attracted the attention of
+morphologists; a large number of observations of this kind are given in the
+handbooks of Masters (Masters, "Vegetable Teratology", London, 1869.) and
+Penzig (Penzig, "Pflanzen-Teratologie, Vols I. and II. Genua, 1890-94.) 
+These variations, which used to be regarded as curiosities, have now
+assumed considerable importance in connection with the causes of form-
+development.  They also possess special interest in relation to the
+question of heredity, a subject which does not at present concern us, as
+such deviations from normal development undoubtedly arise as individual
+variations induced by the influence of environment.
+
+Abnormal developments of all kinds in stems, leaves, and flowers, may be
+produced by parasites, insects, or fungi.  They may also be induced by
+injury, as Blaringhem (Blaringhem, "Mutation et traumatismes", Paris,
+1907.) has more particularly demonstrated, which, by cutting away the
+leading shoots of branches in an early stage of development, caused
+fasciation, torsion, anomalous flowers, etc.  The experiments of Blaringhem
+point to the probability that disturbances in the conditions of food-supply
+consequent on injury are the cause of the production of monstrosities. 
+This is certainly the case in my experiments with species of Sempervivum
+(Klebs, "Kunstliche Metamorphosen", Stuttgart, 1906.); individuals, which
+at first formed normal flowers, produced a great variety of abnormalities
+as the result of changes in nutrition, we may call to mind the fact that
+the formation of inflorescences occurs normally when a vigorous production
+of organic compounds, such as starch, sugar, etc. follows a diminution in
+the supply of mineral salts.  On the other hand, the development of
+inflorescences is entirely suppressed if, at a suitable moment before the
+actual foundations have been laid, water and mineral salts are supplied to
+the roots.  If, during the week when the inflorescence has just been laid
+down and is growing very slowly, the supply of water and salts is
+increased, the internal conditions of the cells are essentially changed. 
+At a later stage, after the elongation of the inflorescence, rosettes of
+leaves are produced instead of flowers, and structures intermediate between
+the two kinds of organs; a number of peculiar plant-forms are thus obtained
+(Cf. Lotsy, "Vorlesungen uber Deszendenztheorien", Vol. II. pl. 3, Jena,
+1908.)  Abnormalities in the greatest variety are produced in flowers by
+varying the time at which the stimulus is applied, and by the cooperation
+of other factors such as temperature, darkness, etc.  In number and
+arrangement the several floral members vary within wide limits; sepals,
+petals, stamens, and carpels are altered in form and colour, a
+transformation of stamens to carpels and from carpels to stamens occurs in
+varying degrees.  The majority of the deviations observed had not
+previously been seen either under natural conditions or in cultivation;
+they were first brought to light through the influence of external factors.
+
+Such transformations of flowers become apparent at a time, which is
+separated by about two months from the period at which the particular cause
+began to act.  There is, therefore, no close connection between the
+appearance of the modifications and the external conditions which prevail
+at the moment.  When we are ignorant of the causes which are operative so
+long before the results are seen, we gain the impression that such
+variations as occur are spontaneous or autonomous expressions of the inner
+nature of the plant.  It is much more likely that, as in Sempervivum, they
+were originally produced by an external stimulus which had previously
+reached the sexual cells or the young embryo.  In any case abnormalities of
+this kind appear to be of a special type as compared with ordinary
+fluctuating variations.  Darwin pointed out this difference; Bateson
+(Bateson, "Materials for the study of Variation", London, 1894, page 5.)
+has attempted to make the distinction sharper, at the same time emphasising
+its importance in heredity.
+
+Bateson applies the term CONTINUOUS to small variations connected with one
+another by transitional stages, while those which are more striking and
+characterised from the first by a certain completeness, he names
+DISCONTINUOUS.  He drew attention to a great difficulty which stands in the
+way of Lamarck's hypothesis, as also of Darwin's view.  "According to both
+theories, specific diversity of form is consequent upon diversity of
+environment, and diversity of environment is thus the ultimate measure of
+diversity of specific form.  Here then we meet the difficulty that diverse
+environments often shade into each other insensibly and form a continuous
+series, whereas the Specific Forms of life which are subject to them on the
+whole form a Discontinuous Series."  This difficulty is, however, not of
+fundamental importance as well authenticated facts have been adduced
+showing that by alteration of the environment discontinuous variations,
+such as alterations in the number and form of members of a flower, may be
+produced.  We can as yet no more explain how this happens than we can
+explain the existence of continuous variations.  We can only assert that
+both kinds of variation arise in response to quantitative alterations in
+external conditions.  The question as to which kind of variation is
+produced depends on the greater or less degree of alteration; it is
+correlated with the state of the particular cells at the moment.
+
+In this short sketch it is only possible to deal superficially with a small
+part of the subject.  It has been clearly shown that in view of the general
+dependence of development on the factors of the environment a number of
+problems are ready for experimental treatment.  One must, however, not
+forget that the science of the physiology of form has not progressed beyond
+its initial stages.  Just now our first duty is to demonstrate the
+dependence on external factors in as many forms of plants as possible, in
+order to obtain a more thorough control of all the different plant-forms.
+The problem is not only to produce at will (and independently of their
+normal mode of life) forms which occur in nature, but also to stimulate
+into operation potentialities which necessarily lie dormant under the
+conditions which prevail in nature.  The constitution of a species is much
+richer in possibilities of development than would appear to be the case
+under normal conditions.  It remains for man to stimulate into activity all
+the potentialities.
+
+But the control of plant-form is only a preliminary step--the foundation
+stones on which to erect a coherent scientific structure.  We must discover
+what are the internal processes in the cell produced by external factors,
+which as a necessary consequence result in the appearance of a definite
+form.  We are here brought into contact with the most obscure problem of
+life.  Progress can only be made pari passu with progress in physics and
+chemistry, and with the growth of our knowledge of nutrition, growth, etc.
+
+Let us take one of the simplest cases--an alteration in form.  A
+cylindrical cell of the alga Stigeoclonium assumes, as Livingstone
+(Livingstone, "On the nature of the stimulus which causes the change of
+form, etc."  "Botanical Gazette", XXX. 1900; also XXXII. 1901.) has shown,
+a spherical form when the osmotic pressure of the culture fluid is
+increased; or a spore of Mucor, which, in a sugar solution grows into a
+branched filament, in the presence of a small quantity of acid (hydrogen
+ions) becomes a comparatively large sphere.  (Ritter, "Ueber Kugelhefe,
+etc."  "Ber. bot. Gesell." Berlin, XXV. page 255, 1907.)  In both cases
+there has undoubtedly been an alteration in the osmotic pressure of the
+cell-sap, but this does not suffice to explain the alteration in form,
+since the unknown alterations, which are induced in the protoplasm, must in
+their turn influence the cell-membrane.  In the case of the very much more
+complex alterations in form, such as we encounter in the course of
+development of plants, there do not appear to be any clues which lead us to
+a deeper insight into the phenomena.  Nevertheless we continue the attempt,
+seeking with the help of any available hypothesis for points of attack,
+which may enable us to acquire a more complete mastery of physiological
+methods.  To quote a single example; I may put the question, what internal
+changes produce a transition from vegetative growth to sexual reproduction?
+
+The facts, which are as clearly established from the lower as for the
+higher plants, teach us that quantitative alteration in the environment
+produces such a transition.  This suggests the conclusion that quantitative
+internal changes in the cells, and with them disturbances in the degree of
+concentration, are induced, through which the chemical reactions are led in
+the direction of sexual reproduction.  An increase in the production of
+organic substances in the presence of light, chiefly of the carbohydrates,
+with a simultaneous decrease in the amount of inorganic salts and water,
+are the cause of the disturbance and at the same time of the alteration in
+the direction of development.  Possibly indeed mineral salts as such are
+not in question, but only in the form of other organic combinations,
+particularly proteid material, so that we are concerned with an alteration
+in the relation of the carbohydrates and proteids.  The difficulties of
+such researches are very great because the methods are not yet sufficiently
+exact to demonstrate the frequently small quantitative differences in
+chemical composition.  Questions relating to the enzymes, which are of the
+greatest importance in all these life-processes, are especially
+complicated.  In any case it is the necessary result of such an hypothesis
+that we must employ chemical methods of investigation in dealing with
+problems connected with the physiology of form.
+
+II.  INFLUENCE OF ENVIRONMENT ON THE TRANSFORMATION OF SPECIES.
+
+The study of the physiology of form-development in a pure species has
+already yielded results and makes slow but sure progress.  The physiology
+of the possibility of the transformation of one species into another is
+based, as yet, rather on pious hope than on accomplished fact.  From the
+first it appeared to be hopeless to investigate physiologically the origin
+of Linnean species and at the same time that of the natural system, an aim
+which Darwin had before him in his enduring work.  The historical sequence
+of events, of which an organism is the expression, can only be treated
+hypothetically with the help of facts supplied by comparative morphology,
+the history of development, geographical distribution, and palaeontology. 
+(See Lotsy, "Vorlesungen" (Jena, I. 1906, II. 1908), for summary of the
+facts.)  A glance at the controversy which is going on today in regard to
+different hypotheses shows that the same material may lead different
+investigators to form entirely different opinions.  Our ultimate aim is to
+find a solution of the problem as to the cause of the origin of species. 
+Indeed such attempts are now being made:  they are justified by the fact
+that under cultivation new and permanent strains are produced; the
+fundamental importance of this was first grasped by Darwin.  New points of
+view in regard to these lines of inquiry have been adopted by H. de Vries
+who has succeeded in obtaining from Oenothera Lamarckiana a number of
+constant "elementary" species.  Even if it is demonstrated that he was
+simply dealing with the complex splitting up of a hybrid (Bateson, "Reports
+to the Evolution Committee of the Royal Society", London, 1902; cf. also
+Lotsy, "Vorlesungen", Vol. I. page 234.), the facts adduced in no sense
+lose their very great value.
+
+We must look at the problem in its simplest form; we find it in every case
+where a new race differs essentially from the original type in a single
+character only; for example, in the colour of the flowers or in the
+petalody of the stamens (doubling of flowers).  In this connection we must
+keep in view the fact that every visible character in a plant is the
+resultant of the cooperation of specific structure, with its various
+potentialities, and the influence of the environment.  We know, that in a
+pure species all characters vary, that a blue-flowering Campanula or a red
+Sempervivum can be converted by experiment into white-flowering forms, that
+a transformation of stamens into petals may be caused by fungi or by the
+influence of changed conditions of nutrition, or that plants in dry and
+poor soil become dwarfed.  But so far as the experiments justify a
+conclusion, it would appear that such alterations are not inherited by the
+offspring.  Like all other variations they appear only so long as special
+conditions prevail in the surroundings.
+
+It has been shown that the case is quite different as regards the white-
+flowering, double or dwarf races, because these retain their characters
+when cultivated under practically identical conditions, and side by side
+with the blue, single-flowering or tall races.  The problem may therefore
+be stated thus:  how can a character, which appears in the one case only
+under the strictly limited conditions of the experiment, in other cases
+become apparent under the very much wider conditions of ordinary
+cultivation?  If a character appears, in these circumstances, in the case
+of all individuals, we then speak of constant races.  In such simple cases
+the essential point is not the creation of a new character but rather an
+ALTERATION OF THIS CHARACTER IN ACCORDANCE WITH THE ENVIRONMENT.  In the
+examples mentioned the modified character in the simple varieties (or a
+number of characters in elementary species) appears more or less suddenly
+and is constant in the above sense.  The result is what de Vries has termed
+a Mutation.  In this connection we must bear in mind the fact that no
+difference, recognisable externally, need exist between individual
+variation and mutation.  Even the most minute quantitative difference
+between two plants may be of specific value if it is preserved under
+similar external conditions during many successive generations.  We do not
+know how this happens.  We may state the problem in other terms; by saying
+that the specific structure must be altered.  It is possible, to some
+extent, to explain this sudden alteration, if we regard it as a chemical
+alteration of structure either in the specific qualities of the proteids or
+of the unknown carriers of life.  In the case of many organic compounds
+their morphological characters (the physical condition, crystalline form,
+etc.) are at once changed by alteration of atomic relations or by
+incorporation of new radicals.  (For instance ethylchloride (C2H5Cl) is a
+gas at 21 deg C., ethylenechloride (C2H4Cl2) a fluid boiling at 84 deg C.,
+beta trichlorethane (C2H3Cl3) a fluid boiling at 113 deg C., perchlorethane
+(C2Cl6) a crystalline substance.  Klebs, ("Willkurliche
+Entwickelungsanderungen" page 158.)  Much more important, however, would be
+an answer to the question, whether an individual variation can be converted
+experimentally into an inherited character--a mutation in de Vries's sense.
+
+In all circumstances we may recognise as a guiding principle the assumption
+adopted by Lamarck, Darwin, and many others, that the inheritance of any
+one character, or in more general terms, the transformation of one species
+into another, is, in the last instance, to be referred to a change in the
+environment.  From a causal-mechanical point of view it is not a priori
+conceivable that one species can ever become changed into another so long
+as external conditions remain constant.  The inner structure of a species
+must be essentially altered by external influences.  Two methods of
+experimental research may be adopted, the effect of crossing distinct
+species and, secondly, the effect of definite factors of the environment.
+
+The subject of hybridisation is dealt with in another part of this essay. 
+It is enough to refer here to the most important fact, that as the result
+of combinations of characters of different species new and constant forms
+are produced.  Further, Tschermack, Bateson and others have demonstrated
+the possibility that hitherto unknown inheritable characters may be
+produced by hybridisation.
+
+The other method of producing constant races by the influence of special
+external conditions has often been employed.  The sporeless races of
+Bacteria and Yeasts (Cf. Detto, "Die Theorie der direkten Anpassung...",
+pages 98 et seq., Jena, 1904; see also Lotsy, "Vorlesungen", II. pages 636
+et seq., where other similar cases are described.) are well known, in which
+an internal alteration of the cells is induced by the influence of poison
+or higher temperature, so that the power of producing spores even under
+normal conditions appears to be lost.  A similar state of things is found
+in some races which under certain definite conditions lose their colour or
+their virulence.  Among the phanerogams the investigations of Schubler on
+cereals afford parallel cases, in which the influence of a northern climate
+produces individuals which ripen their seeds early; these seeds produce
+plants which seed early in southern countries.  Analogous results were
+obtained by Cieslar in his experiments; seeds of conifers from the Alps
+when planted in the plains produced plants of slow growth and small
+diameter.
+
+All these observations are of considerable interest theoretically; they
+show that the action of environment certainly induces such internal
+changes, and that these are transmitted to the next generation.  But as
+regards the main question, whether constant races may be obtained by this
+means, the experiments cannot as yet supply a definite answer.  In
+phanerogams, the influence very soon dies out in succeeding generations; in
+the case of bacteria, in which it is only a question of the loss of a
+character it is relatively easy for this to reappear.  It is not
+impossible, that in all such cases there is a material hanging-on of
+certain internal conditions, in consequence of which the modification of
+the character persists for a time in the descendants, although the original
+external conditions are no longer present.
+
+Thus a slow dying-out of the effect of a stimulus was seen in my
+experiments on Veronica chamaedrys.  (Klebs, "Kunstliche Metamorphosen",
+Stuttgart, 1906, page 132.)  During the cultivation of an artificially
+modified inflorescence I obtained a race showing modifications in different
+directions, among which twisting was especially conspicuous.  This plant,
+however, does not behave as the twisted race of Dipsacus isolated by de
+Vries (de Vries, "Mutationstheorie", Vol. II. Leipzig, 1903, page 573.),
+which produced each year a definite percentage of twisted individuals.  In
+the vegetative reproduction of this Veronica the torsion appeared in the
+first, also in the second and third year, but with diminishing intensity. 
+In spite of good cultivation this character has apparently now disappeared;
+it disappeared still more quickly in seedlings.  In another character of
+the same Veronica chamaedrys the influence of the environment was stronger. 
+The transformation of the inflorescences to foliage-shoots formed the
+starting-point; it occurred only under narrowly defined conditions, namely
+on cultivation as a cutting in moist air and on removal of all other leaf-
+buds.  In the majority (7/10) of the plants obtained from the transformed
+shoots, the modification appeared in the following year without any
+interference.  Of the three plants which were under observation several
+years the first lost the character in a short time, while the two others
+still retain it, after vegetative propagation, in varying degrees.  The
+same character occurs also in some of the seedlings; but anything
+approaching a constant race has not been produced.
+
+Another means of producing new races has been attempted by Blaringhem. 
+(Blaringhem, "Mutation et Traumatisme", Paris, 1907.)  On removing at an
+early stage the main shoots of different plants he observed various
+abnormalities in the newly formed basal shoots.  From the seeds of such
+plants he obtained races, a large percentage of which exhibited these
+abnormalities.  Starting from a male Maize plant with a fasciated
+inflorescence, on which a proportion of the flowers had become male, a new
+race was bred in which hermaphrodite flowers were frequently produced.  In
+the same way Blaringhem obtained, among other similar results, a race of
+barley with branched ears.  These races, however, behaved in essentials
+like those which have been demonstrated by de Vries to be inconstant, e.g.
+Trifolium pratense quinquefolium and others.  The abnormality appears in a
+proportion of the individuals and only under very special conditions.  It
+must be remembered too that Blaringhem worked with old cultivated plants,
+which from the first had been disposed to split into a great variety of
+races.  It is possible, but difficult to prove, that injury contributed to
+this result.
+
+A third method has been adopted by MacDougal (MacDougal, "Heredity and
+Origin of species", "Monist", 1906; "Report of department of botanical
+research", "Fifth Year-book of the Carnegie Institution of Washington",
+page 119, 1907.) who injected strong (10 percent) sugar solution or weak
+solutions of calcium nitrate and zinc sulphate into young carpels of
+different plants.  From the seeds of a plant of Raimannia odorata the
+carpels of which had been thus treated he obtained several plants
+distinguished from the parent-forms by the absence of hairs and by distinct
+forms of leaves.  Further examination showed that he had here to do with a
+new elementary species.  MacDougal also obtained a more or less distinct
+mutant of Oenothera biennis.  We cannot as yet form an opinion as to how
+far the effect is due to the wound or to the injection of fluid as such, or
+to its chemical properties.  This, however, is not so essential as to
+decide whether the mutant stands in any relation to the influence of
+external factors.  It is at any rate very important that this kind of
+investigation should be carried further.
+
+If it could be shown that new and inherited races were obtained by
+MacDougal's method, it would be safe to conclude that the same end might be
+gained by altering the conditions of the food-stuff conducted to the sexual
+cells.  New races or elementary species, however, arise without wounding or
+injection.  This at once raises the much discussed question, how far
+garden-cultivation has led to the creation of new races?  Contrary to the
+opinion expressed by Darwin and others, de Vries ("Mutationstheorie", Vol.
+I. pages 412 et seq.) tried to show that garden-races have been produced
+only from spontaneous types which occur in a wild state or from sub-races,
+which the breeder has accidentally discovered but not originated.  In a
+small number of cases only has de Vries adduced definite proof.  On the
+other side we have the work of Korschinsky (Korschinsky, "Heterogenesis und
+Evolution", "Flora", 1901.) which shows that whole series of garden-races
+have made their appearance only after years of cultivation.  In the
+majority of races we are entirely ignorant of their origin.
+
+It is, however, a fact that if a plant is removed from natural conditions
+into cultivation, a well-marked variation occurs.  The well-known plant-
+breeder L. de Vilmorin (L. de Vilmorin, "Notices sur l'amelioration des
+plantes", Paris, 1886, page 36.), speaking from his own experience, states
+that a plant is induced to "affoler," that is to exhibit all possible
+variations from which the breeder may make a further selection only after
+cultivation for several generations.  The effect of cultivation was
+particularly striking in Veronica chamaedrys (Klebs, "Kunstliche
+Metamorphosen", Stuttgart, 1906, page 152.) which, in spite of its wide
+distribution in nature, varies very little.  After a few years of
+cultivation this "good" and constant species becomes highly variable.  The
+specimens on which the experiments were made were three modified
+inflorescence cuttings, the parent-plants of which certainly exhibited no
+striking abnormalities.  In a short time many hitherto latent
+potentialities became apparent, so that characters, never previously
+observed, or at least very rarely, were exhibited, such as scattered leaf-
+arrangement, torsion, terminal or branched inflorescences, the conversion
+of the inflorescence into foliage-shoots, every conceivable alteration in
+the colour of flowers, the assumption of a green colour by parts of the
+flowers, the proliferation of flowers.
+
+All this points to some disturbance in the species resulting from methods
+of cultivation.  It has, however, not yet been possible to produce constant
+races with any one of these modified characters.  But variations appeared
+among the seedlings, some of which, e.g. yellow variegation, were not
+inheritable, while others have proved constant.  This holds good, so far as
+we know at present, for a small rose-coloured form which is to be reckoned
+as a mutation.  Thus the prospect of producing new races by cultivation
+appears to be full of promise.
+
+So long as the view is held that good nourishment, i.e. a plentiful supply
+of water and salts, constitutes the essential characteristic of garden-
+cultivation, we can hardly conceive that new mutations can be thus
+produced.  But perhaps the view here put forward in regard to the
+production of form throws new light on this puzzling problem.
+
+Good manuring is in the highest degree favourable to vegetative growth, but
+is in no way equally favourable to the formation of flowers.  The
+constantly repeated expression, good or favourable nourishment, is not only
+vague but misleading, because circumstances favourable to growth differ
+from those which promote reproduction; for the production of every form
+there are certain favourable conditions of nourishment, which may be
+defined for each species.  Experience shows that, within definite and often
+very wide limits, it does not depend upon the ABSOLUTE AMOUNT of the
+various food substances, but upon their respective degrees of
+concentration.  As we have already stated, the production of flowers
+follows a relative increase in the amount of carbohydrates formed in the
+presence of light, as compared with the inorganic salts on which the
+formation of albuminous substances depends.  (Klebs, "Kunstliche
+Metamorphosen", page 117.)  The various modifications of flowers are due to
+the fact that a relatively too strong solution of salts is supplied to the
+rudiments of these organs.  As a general rule every plant form depends upon
+a certain relation between the different chemical substances in the cells
+and is modified by an alteration of that relation.
+
+During long cultivation under conditions which vary in very different
+degrees, such as moisture, the amount of salts, light intensity,
+temperature, oxygen, it is possible that sudden and special disturbances in
+the relations of the cell substances have a directive influence on the
+inner organisation of the sexual cells, so that not only inconstant but
+also constant varieties will be formed.
+
+Definite proof in support of this view has not yet been furnished, and we
+must admit that the question as to the cause of heredity remains,
+fundamentally, as far from solution as it was in Darwin's time.  As the
+result of the work of many investigators, particularly de Vries, the
+problem is constantly becoming clearer and more definite.  The penetration
+into this most difficult and therefore most interesting problem of life and
+the creation by experiment of new races or elementary species are no longer
+beyond the region of possibility.
+
+
+XIV.  EXPERIMENTAL STUDY OF THE INFLUENCE OF ENVIRONMENT ON ANIMALS.
+
+By JACQUES LOEB, M.D.
+Professor of Physiology in the University of California.
+
+I. INTRODUCTORY REMARKS.
+
+What the biologist calls the natural environment of an animal is from a
+physical point of view a rather rigid combination of definite forces.  It
+is obvious that by a purposeful and systematic variation of these and by
+the application of other forces in the laboratory, results must be
+obtainable which do not appear in the natural environment.  This is the
+reasoning underlying the modern development of the study of the effects of
+environment upon animal life.  It was perhaps not the least important of
+Darwin's services to science that the boldness of his conceptions gave to
+the experimental biologist courage to enter upon the attempt of controlling
+at will the life-phenomena of animals, and of bringing about effects which
+cannot be expected in Nature.
+
+The systematic physico-chemical analysis of the effect of outside forces
+upon the form and reactions of animals is also our only means of
+unravelling the mechanism of heredity beyond the scope of the Mendelian
+law.  The manner in which a germ-cell can force upon the adult certain
+characters will not be understood until we succeed in varying and
+controlling hereditary characteristics; and this can only be accomplished
+on the basis of a systematic study of the effects of chemical and physical
+forces upon living matter.
+
+Owing to limitation of space this sketch is necessarily very incomplete,
+and it must not be inferred that studies which are not mentioned here were
+considered to be of minor importance.  All the writer could hope to do was
+to bring together a few instances of the experimental analysis of the
+effect of environment, which indicate the nature and extent of our control
+over life-phenomena and which also have some relation to the work of
+Darwin.  In the selection of these instances preference is given to those
+problems which are not too technical for the general reader.
+
+The forces, the influence of which we shall discuss, are in succession
+chemical agencies, temperature, light, and gravitation.  We shall also
+treat separately the effect of these forces upon form and instinctive
+reactions.
+
+II.  THE EFFECTS OF CHEMICAL AGENCIES.
+
+(a)  HETEROGENEOUS HYBRIDISATION.
+
+It was held until recently that hybridisation is not possible except
+between closely related species and that even among these a successful
+hybridisation cannot always be counted upon.  This view was well supported
+by experience.  It is, for instance, well known that the majority of marine
+animals lay their unfertilised eggs in the ocean and that the males shed
+their sperm also into the sea-water.  The numerical excess of the
+spermatozoa over the ova in the sea-water is the only guarantee that the
+eggs are fertilised, for the spermatozoa are carried to the eggs by chance
+and are not attracted by the latter.  This statement is the result of
+numerous experiments by various authors, and is contrary to common belief.
+As a rule all or the majority of individuals of a species in a given region
+spawn on the same day, and when this occurs the sea-water constitutes a
+veritable suspension of sperm.  It has been shown by experiment that in
+fresh sea-water the sperm may live and retain its fertilising power for
+several days.  It is thus unavoidable that at certain periods more than one
+kind of spermatozoon is suspended in the sea-water and it is a matter of
+surprise that the most heterogeneous hybridisations do not constantly
+occur.  The reason for this becomes obvious if we bring together mature
+eggs and equally mature and active sperm of a different family.  When this
+is done no egg is, as a rule, fertilised.  The eggs of a sea-urchin can be
+fertilised by sperm of their own species, or, though in smaller numbers, by
+the sperm of other species of sea-urchins, but not by the sperm of other
+groups of echinoderms, e.g. starfish, brittle-stars, holothurians or
+crinoids, and still less by the sperm of more distant groups of animals. 
+The consensus of opinion seemed to be that the spermatozoon must enter the
+egg through a narrow opening or canal, the so-called micropyle, and that
+the micropyle allowed only the spermatozoa of the same or of a closely
+related species to enter the egg.
+
+It seemed to the writer that the cause of this limitation of hybridisation
+might be of another kind and that by a change in the constitution of the
+sea-water it might be possible to bring about heterogenous hybridisations,
+which in normal sea-water are impossible.  This assumption proved correct.
+Sea-water has a faintly alkaline reaction (in terms of the physical chemist
+its concentration of hydroxyl ions is about (10 to the power minus six)N at
+Pacific Grove, California, and about (10 to the power minus 5)N at Woods
+Hole, Massachusetts).  If we slightly raise the alkalinity of the sea-water
+by adding to it a small but definite quantity of sodium hydroxide or some
+other alkali, the eggs of the sea-urchin can be fertilised with the sperm
+of widely different groups of animals, possibly with the sperm of any
+marine animal which sheds it into the ocean.  In 1903 it was shown that if
+we add from about 0.5 to 0.8 cubic centimetre N/10 sodium hydroxide to 50
+cubic centimetres of sea-water, the eggs of Strongylocentrotus purpuratus
+(a sea-urchin which is found on the coast of California) can be fertilised
+in large quantities by the sperm of various kinds of starfish, brittle-
+stars and holothurians; while in normal sea-water or with less sodium
+hydroxide not a single egg of the same female could be fertilised with the
+starfish sperm which proved effective in the hyper-alkaline sea-water.  The
+sperm of the various forms of starfish was not equally effective for these
+hybridisations; the sperm of Asterias ochracea and A. capitata gave the
+best results, since it was possible to fertilise 50 per cent or more of the
+sea-urchin eggs, while the sperm of Pycnopodia and Asterina fertilised only
+2 per cent of the same eggs.
+
+Godlewski used the same method for the hybridisation of the sea-urchin eggs
+with the sperm of a crinoid (Antedon rosacea).  Kupelwieser afterwards
+obtained results which seemed to indicate the possibility of fertilising
+the eggs of Strongylocentrotus with the sperm of a mollusc (Mytilus.) 
+Recently, the writer succeeded in fertilising the eggs of
+Strongylocentrotus franciscanus with the sperm of a mollusc--Chlorostoma. 
+This result could only be obtained in sea-water the alkalinity of which had
+been increased (through the addition of 0.8 cubic centimetre N/10 sodium
+hydroxide to 50 cubic centimetres of sea-water).  We thus see that by
+increasing the alkalinity of the sea-water it is possible to effect
+heterogeneous hybridisations which are at present impossible in the natural
+environment of these animals.
+
+It is, however, conceivable that in former periods of the earth's history
+such heterogeneous hybridisations were possible.  It is known that in
+solutions like sea-water the degree of alkalinity must increase when the
+amount of carbon-dioxide in the atmosphere is diminished.  If it be true,
+as Arrhenius assumes, that the Ice age was caused or preceded by a
+diminution in the amount of carbon-dioxide in the air, such a diminution
+must also have resulted in an increase of the alkalinity of the sea-water,
+and one result of such an increase must have been to render possible
+heterogeneous hybridisations in the ocean which in the present state of
+alkalinity are practically excluded.
+
+But granted that such hybridisations were possible, would they have
+influenced the character of the fauna?  In other words, are the hybrids
+between sea-urchin and starfish, or better still, between sea-urchin and
+mollusc, capable of development, and if so, what is their character?  The
+first experiment made it appear doubtful whether these heterogeneous
+hybrids could live.  The sea-urchin eggs which were fertilised in the
+laboratory by the spermatozoa of the starfish, as a rule, died earlier than
+those of the pure breeds.  But more recent results indicate that this was
+due merely to deficiencies in the technique of the earlier experiments. 
+The writer has recently obtained hybrid larvae between the sea-urchin egg
+and the sperm of a mollusc (Chlorostoma) which, in the laboratory,
+developed as well and lived as long as the pure breeds of the sea-urchin,
+and there was nothing to indicate any difference in the vitality of the two
+breeds.
+
+So far as the question of heredity is concerned, all the experiments on
+heterogeneous hybridisation of the egg of the sea-urchin with the sperm of
+starfish, brittle-stars, crinoids and molluscs, have led to the same
+result, namely, that the larvae have purely maternal characteristics and
+differ in no way from the pure breed of the form from which the egg is
+taken.  By way of illustration it may be said that the larvae of the sea-
+urchin reach on the third day or earlier (according to species and
+temperature) the so-called pluteus stage, in which they possess a typical
+skeleton; while neither the larvae of the starfish nor those of the mollusc
+form a skeleton at the corresponding stage.  It was, therefore, a matter of
+some interest to find out whether or not the larvae produced by the
+fertilisation of the sea-urchin egg with the sperm of starfish or mollusc
+would form the normal and typical pluteus skeleton.  This was invariably
+the case in the experiments of Godlewski, Kupelwieser, Hagedoorn, and the
+writer.  These hybrid larvae were exclusively maternal in character.
+
+It might be argued that in the case of heterogeneous hybridisation the
+sperm-nucleus does not fuse with the egg-nucleus, and that, therefore, the
+spermatozoon cannot transmit its hereditary substances to the larvae.  But
+these objections are refuted by Godlewski's experiments, in which he showed
+definitely that if the egg of the sea-urchin is fertilised with the sperm
+of a crinoid the fusion of the egg-nucleus and sperm-nucleus takes place in
+the normal way.  It remains for further experiments to decide what the
+character of the adult hybrids would be.
+
+(b).  ARTIFICIAL PARTHENOGENESIS.
+
+Possibly in no other field of Biology has our ability to control life-
+phenomena by outside conditions been proved to such an extent as in the
+domain of fertilisation.  The reader knows that the eggs of the
+overwhelming majority of animals cannot develop unless a spermatozoon
+enters them.  In this case a living agency is the cause of development and
+the problem arises whether it is possible to accomplish the same result
+through the application of well-known physico-chemical agencies.  This is,
+indeed, true, and during the last ten years living larvae have been
+produced by chemical agencies from the unfertilised eggs of sea-urchins,
+starfish, holothurians and a number of annelids and molluscs; in fact this
+holds true in regard to the eggs of practically all forms of animals with
+which such experiments have been tried long enough.  In each form the
+method of procedure is somewhat different and a long series of experiments
+is often required before the successful method is found.
+
+The facts of Artificial Parthenogenesis, as the chemical fertilisation of
+the egg is called, have, perhaps, some bearing on the problem of evolution.
+If we wish to form a mental image of the process of evolution we have to
+reckon with the possibility that parthenogenetic propagation may have
+preceded sexual reproduction.  This suggests also the possibility that at
+that period outside forces may have supplied the conditions for the
+development of the egg which at present the spermatozoon has to supply. 
+For this, if for no other reason, a brief consideration of the means of
+artificial parthenogenesis may be of interest to the student of evolution.
+
+It seemed necessary in these experiments to imitate as completely as
+possible by chemical agencies the effects of the spermatozoon upon the egg.
+When a spermatozoon enters the egg of a sea-urchin or certain starfish or
+annelids, the immediate effect is a characteristic change of the surface of
+the egg, namely the formation of the so-called membrane of fertilisation. 
+The writer found that we can produce this membrane in the unfertilised egg
+by certain acids, especially the monobasic acids of the fatty series, e.g.
+formic, acetic, propionic, butyric, etc.  Carbon-dioxide is also very
+efficient in this direction.  It was also found that the higher acids are
+more efficient than the lower ones, and it is possible that the
+spermatozoon induces membrane-formation by carrying into the egg a higher
+fatty acid, namely oleic acid or one of its salts or esters.
+
+The physico-chemical process which underlies the formation of the membrane
+seems to be the cause of the development of the egg.  In all cases in which
+the unfertilised egg has been treated in such a way as to cause it to form
+a membrane it begins to develop.  For the eggs of certain animals membrane-
+formation is all that is required to induce a complete development of the
+unfertilised egg, e.g. in the starfish and certain annelids.  For the eggs
+of other animals a second treatment is necessary, presumably to overcome
+some of the injurious effects of acid treatment.  Thus the unfertilised
+eggs of the sea-urchin Strongylocentrotus purpuratus of the Californian
+coast begin to develop when membrane-formation has been induced by
+treatment with a fatty acid, e.g. butyric acid; but the development soon
+ceases and the eggs perish in the early stages of segmentation, or after
+the first nuclear division.  But if we treat the same eggs, after membrane-
+formation, for from 35 to 55 minutes (at 15 deg C.) with sea-water the
+concentration (osmotic pressure) of which has been raised through the
+addition of a definite amount of some salt or sugar, the eggs will segment
+and develop normally, when transferred back to normal sea-water.  If care
+is taken, practically all the eggs can be caused to develop into plutei,
+the majority of which may be perfectly normal and may live as long as
+larvae produced from eggs fertilised with sperm.
+
+It is obvious that the sea-urchin egg is injured in the process of
+membrane-formation and that the subsequent treatment with a hypertonic
+solution only acts as a remedy.  The nature of this injury became clear
+when it was discovered that all the agencies which cause haemolysis, i.e.
+the destruction of the red blood corpuscles, also cause membrane-formation
+in unfertilised eggs, e.g. fatty acids or ether, alcohols or chloroform,
+etc., or saponin, solanin, digitalin, bile salts and alkali.  It thus
+happens that the phenomena of artificial parthenogenesis are linked
+together with the phenomena of haemolysis which at present play so
+important a role in the study of immunity.  The difference between
+cytolysis (or haemolysis) and fertilisation seems to be this, that the
+latter is caused by a superficial or slight cytolysis of the egg, while if
+the cytolytic agencies have time to act on the whole egg the latter is
+completely destroyed.  If we put unfertilised eggs of a sea-urchin into
+sea-water which contains a trace of saponin we notice that, after a few
+minutes, all the eggs form the typical membrane of fertilisation.  If the
+eggs are then taken out of the saponin solution, freed from all traces of
+saponin by repeated washing in normal sea-water, and transferred to the
+hypertonic sea-water for from 35 to 55 minutes, they develop into larvae. 
+If, however, they are left in the sea-water containing the saponin they
+undergo, a few minutes after membrane-formation, the disintegration known
+in pathology as CYTOLYSIS.  Membrane-formation is, therefore, caused by a
+superficial or incomplete cytolysis.  The writer believes that the
+subsequent treatment of the egg with hypertonic sea-water is needed only to
+overcome the destructive effects of this partial cytolysis.  The full
+reasons for this belief cannot be given in a short essay.
+
+Many pathologists assume that haemolysis or cytolysis is due to a
+liquefaction of certain fatty or fat-like compounds, the so-called lipoids,
+in the cell.  If this view is correct, it would be necessary to ascribe the
+fertilisation of the egg to the same process.
+
+The analogy between haemolysis and fertilisation throws, possibly, some
+light on a curious observation.  It is well known that the blood
+corpuscles, as a rule, undergo cytolysis if injected into the blood of an
+animal which belongs to a different family.  The writer found last year
+that the blood of mammals, e.g. the rabbit, pig, and cattle, causes the egg
+of Strongylocentrotus to form a typical fertilisation-membrane.  If such
+eggs are afterwards treated for a short period with hypertonic sea-water
+they develop into normal larvae (plutei).  Some substance contained in the
+blood causes, presumably, a superficial cytolysis of the egg and thus
+starts its development.
+
+We can also cause the development of the sea-urchin egg without membrane-
+formation.  The early experiments of the writer were done in this way and
+many experimenters still use such methods.  It is probable that in this
+case the mechanism of fertilisation is essentially the same as in the case
+where the membrane-formation is brought about, with this difference only,
+that the cytolytic effect is less when no fertilisation-membrane is formed.
+This inference is corroborated by observations on the fertilisation of the
+sea-urchin egg with ox blood.  It very frequently happens that not all of
+the eggs form membranes in this process.  Those eggs which form membranes
+begin to develop, but perish if they are not treated with hypertonic sea-
+water.  Some of the other eggs, however, which do not form membranes,
+develop directly into normal larvae without any treatment with hypertonic
+sea-water, provided they are exposed to the blood for only a few minutes. 
+Presumably some blood enters the eggs and causes the cytolytic effects in a
+less degree than is necessary for membrane-formation, but in a sufficient
+degree to cause their development.  The slightness of the cytolytic effect
+allows the egg to develop without treatment with hypertonic sea-water.
+
+Since the entrance of the spermatozoon causes that degree of cytolysis
+which leads to membrane-formation, it is probable that, in addition to the
+cytolytic or membrane-forming substance (presumably a higher fatty acid),
+it carries another substance into the egg which counteracts the deleterious
+cytolytic effects underlying membrane-formation.
+
+The question may be raised whether the larvae produced by artificial
+parthenogenesis can reach the mature stage.  This question may be answered
+in the affirmative, since Delage has succeeded in raising several
+parthenogenetic sea-urchin larvae beyond the metamorphosis into the adult
+stage and since in all the experiments made by the writer the
+parthenogenetic plutei lived as long as the plutei produced from fertilised
+eggs.
+
+(c).  ON THE PRODUCTION OF TWINS FROM ONE EGG THROUGH A CHANGE IN THE
+CHEMICAL CONSTITUTION OF THE SEA-WATER.
+
+The reader is probably familiar with the fact that there exist two
+different types of human twins.  In the one type the twins differ as much
+as two children of the same parents born at different periods; they may or
+may not have the same sex.  In the second type the twins have invariably
+the same sex and resemble each other most closely.  Twins of the latter
+type are produced from the same egg, while twins of the former type are
+produced from two different eggs.
+
+The experiments of Driesch and others have taught us that twins originate
+from one egg in this manner, namely, that the first two cells into which
+the egg divides after fertilisation become separated from each other.  This
+separation can be brought about by a change in the chemical constitution of
+the sea-water.  Herbst observed that if the fertilised eggs of the sea-
+urchin are put into sea-water which is freed from calcium, the cells into
+which the egg divides have a tendency to fall apart.  Driesch afterwards
+noticed that eggs of the sea-urchin treated with sea-water which is free
+from lime have a tendency to give rise to twins.  The writer has recently
+found that twins can be produced not only by the absence of lime, but also
+through the absence of sodium or of potassium; in other words, through the
+absence of one or two of the three important metals in the sea-water. 
+There is, however, a second condition, namely, that the solution used for
+the production of twins must have a neutral or at least not an alkaline
+reaction.
+
+The procedure for the production of twins in the sea-urchin egg consists
+simply in this:--the eggs are fertilised as usual in normal sea-water and
+then, after repeated washing in a neutral solution of sodium chloride (of
+the concentration of the sea-water), are placed in a neutral mixture of
+potassium chloride and calcium chloride, or of sodium chloride and
+potassium chloride, or of sodium chloride and calcium chloride, or of
+sodium chloride and magnesium chloride.  The eggs must remain in this
+solution until half an hour or an hour after they have reached the two-cell
+stage.  They are then transferred into normal sea-water and allowed to
+develop.  From 50 to 90 per cent of the eggs of Strongylocentrotus
+purpuratus treated in this manner may develop into twins.  These twins may
+remain separate or grow partially together and form double monsters, or
+heal together so completely that only slight or even no imperfections
+indicate that the individual started its career as a pair of twins.  It is
+also possible to control the tendency of such twins to grow together by a
+change in the constitution of the sea-water.  If we use as a twin-producing
+solution a mixture of sodium, magnesium and potassium chlorides (in the
+proportion in which these salts exist in the sea-water) the tendency of the
+twins to grow together is much more pronounced than if we use simply a
+mixture of sodium chloride and magnesium chloride.
+
+The mechanism of the origin of twins, as the result of altering the
+composition of the sea-water, is revealed by observation of the first
+segmentation of the egg in these solutions.  This cell-division is modified
+in a way which leads to a separation of the first two cells.  If the egg is
+afterwards transferred back into normal sea-water, each of these two cells
+develops into an independent embryo.  Since normal sea-water contains all
+three metals, sodium, calcium, and potassium, and since it has besides an
+alkaline reaction, we perceive the reason why twins are not normally
+produced from one egg.  These experiments suggest the possibility of a
+chemical cause for the origin of twins from one egg or of double
+monstrosities in mammals.  If, for some reason, the liquids which surround
+the human egg a short time before and after the first cell-division are
+slightly acid, and at the same time lacking in one of the three important
+metals, the conditions for the separation of the first two cells and the
+formation of identical twins are provided.
+
+In conclusion it may be pointed out that the reverse result, namely, the
+fusion of normally double organs, can also be brought about experimentally
+through a change in the chemical constitution of the sea-water.  Stockard
+succeeded in causing the eyes of fish embryos (Fundulus heteroclitus) to
+fuse into a single cyclopean eye through the addition of magnesium chloride
+to the sea-water.  When he added about 6 grams of magnesium chloride to 100
+cubic centimetres of sea-water and placed the fertilised eggs in the
+mixture, about 50 per cent of the eggs gave rise to one-eyed embryos. 
+"When the embryos were studied the one-eyed condition was found to result
+from the union or fusion of the 'anlagen' of the two eyes.  Cases were
+observed which showed various degrees in this fusion; it appeared as though
+the optic vessels were formed too far forward and ventral, so that their
+antero-ventro-median surfaces fused.  This produces one large optic cup,
+which in all cases gives more or less evidence of its double nature." 
+(Stockard, "Archiv f. Entwickelungsmechanik", Vol. 23, page 249, 1907.)
+
+We have confined ourselves to a discussion of rather simple effects of the
+change in the constitution of the sea-water upon development.  It is a
+priori obvious, however, that an unlimited number of pathological
+variations might be produced by a variation in the concentration and
+constitution of the sea-water, and experience confirms this statement.  As
+an example we may mention the abnormalities observed by Herbst in the
+development of sea-urchins through the addition of lithium to sea-water. 
+It is, however, as yet impossible to connect in a rational way the effects
+produced in this and similar cases with the cause which produced them; and
+it is also impossible to define in a simple way the character of the change
+produced.
+
+III.  THE INFLUENCE OF TEMPERATURE.
+
+(a)  THE INFLUENCE OF TEMPERATURE UPON THE DENSITY OF PELAGIC ORGANISMS AND
+THE DURATION OF LIFE.
+
+It has often been noticed by explorers who have had a chance to compare the
+faunas in different climates that in polar seas such species as thrive at
+all in those regions occur, as a rule, in much greater density than they do
+in the moderate or warmer regions of the ocean.  This refers to those
+members of the fauna which live at or near the surface, since they alone
+lend themselves to a statistical comparison.  In his account of the
+Valdivia expedition, Chun (Chun, "Aus den Tiefen des Weltmeeres", page 225,
+Jena, 1903.) calls especial attention to this quantitative difference in
+the surface fauna and flora of different regions.  "In the icy water of the
+Antarctic, the temperature of which is below 0 deg C., we find an
+astonishingly rich animal and plant life.  The same condition with which we
+are familiar in the Arctic seas is repeated here, namely, that the quantity
+of plankton material exceeds that of the temperate and warm seas."  And
+again, in regard to the pelagic fauna in the region of the Kerguelen
+Islands, he states:  "The ocean is alive with transparent jelly fish,
+Ctenophores (Bolina and Callianira) and of Siphonophore colonies of the
+genus Agalma."
+
+The paradoxical character of this general observation lies in the fact that
+a low temperature retards development, and hence should be expected to have
+the opposite effect from that mentioned by Chun.  Recent investigations
+have led to the result that life-phenomena are affected by temperature in
+the same sense as the velocity of chemical reactions.  In the case of the
+latter van't Hoff had shown that a decrease in temperature by 10 degrees
+reduces their velocity to one half or less, and the same has been found for
+the influence of temperature on the velocity of physiological processes. 
+Thus Snyder and T.B. Robertson found that the rate of heartbeat in the
+tortoise and in Daphnia is reduced to about one-half if the temperature is
+lowered 10 deg C., and Maxwell, Keith Lucas, and Snyder found the same
+influence of temperature for the rate with which an impulse travels in the
+nerve.  Peter observed that the rate of development in a sea-urchin's egg
+is reduced to less than one-half if the temperature (within certain limits)
+is reduced by 10 degrees.  The same effect of temperature upon the rate of
+development holds for the egg of the frog, as Cohen and Peter calculated
+from the experiments of O. Hertwig.  The writer found the same temperature-
+coefficient for the rate of maturation of the egg of a mollusc (Lottia).
+
+All these facts prove that the velocity of development of animal life in
+Arctic regions, where the temperature is near the freezing point of water,
+must be from two to three times smaller than in regions where the
+temperature of the ocean is about 10 deg C. and from four to nine times
+smaller than in seas the temperature of which is about 20 deg C.  It is,
+therefore, exactly the reverse of what we should expect when authors state
+that the density of organisms at or near the surface of the ocean in polar
+regions is greater than in more temperate regions.
+
+The writer believes that this paradox finds its explanation in experiments
+which he has recently made on the influence of temperature on the duration
+of life of cold-blooded marine animals.  The experiments were made on the
+fertilised and unfertilised eggs of the sea-urchin, and yielded the result
+that for the lowering of temperature by 1 deg C. the duration of life was
+about doubled.  Lowering the temperature by 10 degrees therefore prolongs
+the life of the organism 2 to the power 10, i.e. over a thousand times, and
+a lowering by 20 degrees prolongs it about one million times.  Since this
+prolongation of life is far in excess of the retardation of development
+through a lowering of temperature, it is obvious that, in spite of the
+retardation of development in Arctic seas, animal life must be denser there
+than in temperate or tropical seas.  The excessive increase of the duration
+of life at the poles will necessitate the simultaneous existence of more
+successive generations of the same species in these regions than in the
+temperate or tropical regions.
+
+The writer is inclined to believe that these results have some bearing upon
+a problem which plays an important role in theories of evolution, namely,
+the cause of natural death.  It has been stated that the processes of
+differentiation and development lead also to the natural death of the
+individual.  If we express this in chemical terms it means that the
+chemical processes which underlie development also determine natural death. 
+Physical chemistry has taught us to identify two chemical processes even if
+only certain of their features are known.  One of these means of
+identification is the temperature coefficient.  When two chemical processes
+are identical, their velocity must be reduced by the same amount if the
+temperature is lowered to the same extent.  The temperature coefficient for
+the duration of life of cold-blooded organisms seems, however, to differ
+enormously from the temperature coefficient for their rate of development. 
+For a difference in temperature of 10 deg C. the duration of life is
+altered five hundred times as much as the rate of development; and, for a
+change of 20 deg C., it is altered more than a hundred thousand times as
+much.  From this we may conclude that, at least for the sea-urchin eggs and
+embryo, the chemical processes which determine natural death are certainly
+not identical with the processes which underlie their development.  T.B.
+Robertson has also arrived at the conclusion, for quite different reasons,
+that the process of senile decay is essentially different from that of
+growth and development.
+
+(b)  CHANGES IN THE COLOUR OF BUTTERFLIES PRODUCED THROUGH THE INFLUENCE OF
+TEMPERATURE.
+
+The experiments of Dorfmeister, Weismann, Merrifield, Standfuss, and
+Fischer, on seasonal dimorphism and the aberration of colour in butterflies
+have so often been discussed in biological literature that a short
+reference to them will suffice.  By seasonal dimorphism is meant the fact
+that species may appear at different seasons of the year in a somewhat
+different form or colour.  Vanessa prorsa is the summer form, Vanessa
+levana the winter form of the same species.  By keeping the pupae of
+Vanessa prorsa several weeks at a temperature of from 0 deg to 1 deg
+Weismann succeeded in obtaining from the summer chrysalids specimens which
+resembled the winter variety, Vanessa levana.
+
+If we wish to get a clear understanding of the causes of variation in the
+colour and pattern of butterflies, we must direct our attention to the
+experiments of Fischer, who worked with more extreme temperatures than his
+predecessors, and found that almost identical aberrations of colour could
+be produced by both extremely high and extremely low temperatures.  This
+can be clearly seen from the following tabulated results of his
+observations.  At the head of each column the reader finds the temperature
+to which Fischer submitted the pupae, and in the vertical column below are
+found the varieties that were produced.  In the vertical column A are given
+the normal forms:
+
+(Temperatures in deg C.)
+0 to -20     0 to +10    A.           +35 to +37    +36 to +41  +42 to +46
+                        (Normal forms)
+
+ichnusoides  polaris     urticae      ichnusa       polaris     ichnusoides
+  (nigrita)                                                       (nigrita)
+
+antigone     fischeri    io             -           fischeri    antigone
+  (iokaste)                                                       (iokaste)
+
+testudo      dixeyi      polychloros  erythromelas  dixeyi      testudo
+
+hygiaea      artemis     antiopa      epione        artemis     hygiaea
+
+elymi        wiskotti    cardui         -           wiskotti    elymi
+
+klymene      merrifieldi atalanta       -           merrifieldi klymene
+
+weismanni    porima      prorsa         -           porima      weismanni
+
+The reader will notice that the aberrations produced at a very low
+temperature (from 0 to -20 deg C.) are absolutely identical with the
+aberrations produced by exposing the pupae to extremely high temperatures
+(42 to 46 deg C.).  Moreover the aberrations produced by a moderately low
+temperature (from 0 to 10 deg C.) are identical with the aberrations
+produced by a moderately high temperature (36 to 41 deg C.)
+
+From these observations Fischer concludes that it is erroneous to speak of
+a specific effect of high and of low temperatures, but that there must be a
+common cause for the aberration found at the high as well as at the low
+temperature limits.  This cause he seems to find in the inhibiting effects
+of extreme temperatures upon development.
+
+If we try to analyse such results as Fischer's from a physico-chemical
+point of view, we must realise that what we call life consists of a series
+of chemical reactions, which are connected in a catenary way; inasmuch as
+one reaction or group of reactions (a) (e.g. hydrolyses) causes or
+furnishes the material for a second reaction or group of reactions (b)
+(e.g. oxydations).  We know that the temperature coefficient for
+physiological processes varies slightly at various parts of the scale; as a
+rule it is higher near 0 and lower near 30 deg.  But we know also that the
+temperature coefficients do not vary equally from the various physiological
+processes.  It is, therefore, to be expected that the temperature
+coefficients for the group of reactions of the type (a) will not be
+identical through the whole scale with the temperature coefficients for the
+reactions of the type (b).  If therefore a certain substance is formed at
+the normal temperature of the animal in such quantities as are needed for
+the catenary reaction (b), it is not to be expected that this same perfect
+balance will be maintained for extremely high or extremely low
+temperatures; it is more probable that one group of reactions will exceed
+the other and thus produce aberrant chemical effects, which may underlie
+the colour aberrations observed by Fischer and other experimenters.
+
+It is important to notice that Fischer was also able to produce aberrations
+through the application of narcotics.  Wolfgang Ostwald has produced
+experimentally, through variation of temperature, dimorphism of form in
+Daphnia.  Lack of space precludes an account of these important
+experiments, as of so many others.
+
+IV.  THE EFFECTS OF LIGHT.
+
+At the present day nobody seriously questions the statement that the action
+of light upon organisms is primarily one of a chemical character.  While
+this chemical action is of the utmost importance for organisms, the
+nutrition of which depends upon the action of chlorophyll, it becomes of
+less importance for organisms devoid of chlorophyll.  Nevertheless, we find
+animals in which the formation of organs by regeneration is not possible
+unless they are exposed to light.  An observation made by the writer on the
+regeneration of polyps in a hydroid, Eudendrium racemosum, at Woods Hole,
+may be mentioned as an instance of this.  If the stem of this hydroid,
+which is usually covered with polyps, is put into an aquarium the polyps
+soon fall off.  If the stems are kept in an aquarium where light strikes
+them during the day, a regeneration of numerous polyps takes place in a few
+days.  If, however, the stems of Eudendrium are kept permanently in the
+dark, no polyps are formed even after an interval of some weeks; but they
+are formed in a few days after the same stems have been transferred from
+the dark to the light.  Diffused daylight suffices for this effect. 
+Goldfarb, who repeated these experiments, states that an exposure of
+comparatively short duration is sufficient for this effect, it is possible
+that the light favours the formation of substances which are a prerequisite
+for the origin of polyps and their growth.
+
+Of much greater significance than this observation are the facts which show
+that a large number of animals assume, to some extent, the colour of the
+ground on which they are placed.  Pouchet found through experiments upon
+crustaceans and fish that this influence of the ground on the colour of
+animals is produced through the medium of the eyes.  If the eyes are
+removed or the animals made blind in another way these phenomena cease. 
+The second general fact found by Pouchet was that the variation in the
+colour of the animal is brought about through an action of the nerves on
+the pigment-cells of the skin; the nerve-action being induced through the
+agency of the eye.
+
+The mechanism and the conditions for the change in colouration were made
+clear through the beautiful investigations of Keeble and Gamble, on the
+colour-change in crustaceans.  According to these authors the pigment-cells
+can, as a rule, be considered as consisting of a central body from which a
+system of more or less complicated ramifications or processes spreads out
+in all directions.  As a rule, the centre of the cell contains one or more
+different pigments which under the influence of nerves can spread out
+separately or together into the ramifications.  These phenomena of
+spreading and retraction of the pigments into or from the ramifications of
+the pigment-cells form on the whole the basis for the colour changes under
+the influence of environment.  Thus Keeble and Gamble observed that
+Macromysis flexuosa appears transparent and colourless or grey on sandy
+ground.  On a dark ground their colour becomes darker.  These animals have
+two pigments in their chromatophores, a brown pigment and a whitish or
+yellow pigment; the former is much more plentiful than the latter.  When
+the animal appears transparent all the pigment is contained in the centre
+of the cells, while the ramifications are free from pigment.  When the
+animal appears brown both pigments are spread out into the ramifications. 
+In the condition of maximal spreading the animals appear black.
+
+This is a comparatively simple case.  Much more complicated conditions were
+found by Keeble and Gamble in other crustaceans, e.g. in Hippolyte
+cranchii, but the influence of the surroundings upon the colouration of
+this form was also satisfactorily analysed by these authors.
+
+While many animals show transitory changes in colour under the influence of
+their surroundings, in a few cases permanent changes can be produced.  The
+best examples of this are those which were observed by Poulton in the
+chrysalids of various butterflies, especially the small tortoise-shell. 
+These experiments are so well known that a short reference to them will
+suffice.  Poulton (Poulton, E.B., "Colours of Animals" (The International
+Scientific Series), London, 1890, page 121.) found that in gilt or white
+surroundings the pupae became light coloured and there was often an immense
+development of the golden spots, "so that in many cases the whole surface
+of the pupae glittered with an apparent metallic lustre.  So remarkable was
+the appearance that a physicist to whom I showed the chrysalids, suggested
+that I had played a trick and had covered them with goldleaf."  When black
+surroundings were used "the pupae were as a rule extremely dark, with only
+the smallest trace, and often no trace at all, of the golden spots which
+are so conspicuous in the lighter form."  The susceptibility of the animal
+to this influence of its surroundings was found to be greatest during a
+definite period when the caterpillar undergoes the metamorphosis into the
+chrysalis stage.  As far as the writer is aware, no physico-chemical
+explanation, except possibly Wiener's suggestion of colour-photography by
+mechanical colour adaptation, has ever been offered for the results of the
+type of those observed by Poulton.
+
+V.  EFFECTS OF GRAVITATION.
+
+(a)  EXPERIMENTS ON THE EGG OF THE FROG.
+
+Gravitation can only indirectly affect life-phenomena; namely, when we have
+in a cell two different non-miscible liquids (or a liquid and a solid) of
+different specific gravity, so that a change in the position of the cell or
+the organ may give results which can be traced to a change in the position
+of the two substances.  This is very nicely illustrated by the frog's egg,
+which has two layers of very viscous protoplasm one of which is black and
+one white.  The dark one occupies normally the upper position in the egg
+and may therefore be assumed to possess a smaller specific gravity than the
+white substance.  When the egg is turned with the white pole upwards a
+tendency of the white protoplasm to flow down again manifests itself.  It
+is, however, possible to prevent or retard this rotation of the highly
+viscous protoplasm, by compressing the eggs between horizontal glass
+plates.  Such compression experiments may lead to rather interesting
+results, as O. Schultze first pointed out.  Pflueger had already shown that
+the first plane of division in a fertilised frog's egg is vertical and Roux
+established the fact that the first plane of division is identical with the
+plane of symmetry of the later embryo.  Schultze found that if the frog's
+egg is turned upside down at the time of its first division and kept in
+this abnormal position, through compression between two glass plates for
+about 20 hours, a small number of eggs may give rise to twins.  It is
+possible, in this case, that the tendency of the black part of the egg to
+rotate upwards along the surface of the egg leads to a separation of its
+first cells, such a separation leading to the formation of twins.
+
+T.H. Morgan made an interesting additional observation.  He destroyed one
+half of the egg after the first segmentation and found that the half which
+remained alive gave rise to only one half of an embryo, thus confirming an
+older observation of Roux.  When, however, Morgan put the egg upside down
+after the destruction of one of the first two cells, and compressed the
+eggs between two glass plates, the surviving half of the egg gave rise to a
+perfect embryo of half size (and not to a half embryo of normal size as
+before.)  Obviously in this case the tendency of the protoplasm to flow
+back to its normal position was partially successful and led to a partial
+or complete separation of the living from the dead half; whereby the former
+was enabled to form a whole embryo, which, of course, possessed only half
+the size of an embryo originating from a whole egg.
+
+(b)  EXPERIMENTS ON HYDROIDS.
+
+A striking influence of gravitation can be observed in a hydroid,
+Antennularia antennina, from the bay of Naples.  This hydroid consists of a
+long straight main stem which grows vertically upwards and which has at
+regular intervals very fine and short bristle-like lateral branches, on the
+upper side of which the polyps grow.  The main stem is negatively
+geotropic, i.e. its apex continues to grow vertically upwards when we put
+it obliquely into the aquarium, while the roots grow vertically downwards.
+The writer observed that when the stem is put horizontally into the water
+the short lateral branches on the lower side give rise to an altogether
+different kind of organ, namely, to roots, and these roots grow
+indefinitely in length and attach themselves to solid bodies; while if the
+stem had remained in its normal position no further growth would have
+occurred in the lateral branches.  From the upper side of the horizontal
+stem new stems grow out, mostly directly from the original stem,
+occasionally also from the short lateral branches.  It is thus possible to
+force upon this hydroid an arrangement of organs which is altogether
+different from the hereditary arrangement.  The writer had called the
+change in the hereditary arrangement of organs or the transformation of
+organs by external forces HETEROMORPHOSIS.  We cannot now go any further
+into this subject, which should, however, prove of interest in relation to
+the problem of heredity.
+
+If it is correct to apply inferences drawn from the observation on the
+frog's egg to the behaviour of Antennularia, one might conclude that the
+cells of Antennularia also contain non-miscible substances of different
+specific gravity, and that wherever the specifically lighter substance
+comes in contact with the sea-water (or gets near the surface of the cell)
+the growth of a stem is favoured; while contact with the sea-water of the
+specifically heavier of the substances, will favour the formation of roots.
+
+VI.  THE EXPERIMENTAL CONTROL OF ANIMAL INSTINCTS.
+
+(a)  EXPERIMENTS ON THE MECHANISM OF HELIOTROPIC REACTIONS IN ANIMALS.
+
+Since the instinctive reactions of animals are as hereditary as their
+morphological character, a discussion of experiments on the physico-
+chemical character of the instinctive reactions of animals should not be
+entirely omitted from this sketch.  It is obvious that such experiments
+must begin with the simplest type of instincts, if they are expected to
+lead to any results; and it is also obvious that only such animals must be
+selected for this purpose, the reactions of which are not complicated by
+associative memory, or, as it may preferably be termed, associative
+hysteresis.
+
+The simplest type of instincts is represented by the purposeful motions of
+animals to or from a source of energy, e.g. light; and it is with some of
+these that we intend to deal here.  When we expose winged aphides (after
+they have flown away from the plant), or young caterpillars of Porthesia
+chrysorrhoea (when they are aroused from their winter sleep) or marine or
+freshwater copepods and many other animals, to diffused daylight falling in
+from a window, we notice a tendency among these animals to move towards the
+source of light.  If the animals are naturally sensitive, or if they are
+rendered sensitive through the agencies which we shall mention later, and
+if the light is strong enough, they move towards the source of light in as
+straight a line as the imperfections and peculiarities of their locomotor
+apparatus will permit.  It is also obvious that we are here dealing with a
+forced reaction in which the animals have no more choice in the direction
+of their motion than have the iron filings in their arrangement in a
+magnetic field.  This can be proved very nicely in the case of starving
+caterpillars of Porthesia.  The writer put such caterpillars into a glass
+tube the axis of which was at right angles to the plane of the window:  the
+caterpillars went to the window side of the tube and remained there, even
+if leaves of their food-plant were put into the tube directly behind them. 
+Under such conditions the animals actually died from starvation, the light
+preventing them from turning to the food, which they eagerly ate when the
+light allowed them to do so.  One cannot say that these animals, which we
+call positively helioptropic, are attracted by the light, since it can be
+shown that they go towards the source of the light even if in so doing they
+move from places of a higher to places of a lower degree of illumination.
+
+The writer has advanced the following theory of these instinctive
+reactions.  Animals of the type of those mentioned are automatically
+orientated by the light in such a way that symmetrical elements of their
+retina (or skin) are struck by the rays of light at the same angle.  In
+this case the intensity of light is the same for both retinae or
+symmetrical parts of the skin.
+
+This automatic orientation is determined by two factors, first a peculiar
+photo-sensitiveness of the retina (or skin), and second a peculiar nervous
+connection between the retina and the muscular apparatus.  In symmetrically
+built heliotropic animals in which the symmetrical muscles participate
+equally in locomotion, the symmetrical muscles work with equal energy as
+long as the photo-chemical processes in both eyes are identical.  If,
+however, one eye is struck by stronger light than the other, the
+symmetrical muscles will work unequally and in positively heliotropic
+animals those muscles will work with greater energy which bring the plane
+of symmetry back into the direction of the rays of light and the head
+towards the source of light.  As soon as both eyes are struck by the rays
+of light at the same angle, there is no more reason for the animal to
+deviate from this direction and it will move in a straight line.  All this
+holds good on the supposition that the animals are exposed to only one
+source of light and are very sensitive to light.
+
+Additional proof for the correctness of this theory was furnished through
+the experiments of G.H. Parker and S.J. Holmes.  The former worked on a
+butterfly, Vanessa antiope, the latter on other arthropods.  All the
+animals were in a marked degree positively heliotropic.  These authors
+found that if one cornea is blackened in such an animal, it moves
+continually in a circle when it is exposed to a source of light, and in
+these motions the eye which is not covered with paint is directed towards
+the centre of the circle.  The animal behaves, therefore, as if the
+darkened eye were in the shade.
+
+(b)  THE PRODUCTION OF POSITIVE HELIOTROPISM BY ACIDS AND OTHER MEANS AND
+THE PERIODIC DEPTH-MIGRATIONS OF PELAGIC ANIMALS.
+
+When we observe a dense mass of copepods collected from a freshwater pond,
+we notice that some have a tendency to go to the light while others go in
+the opposite direction and many, if not the majority, are indifferent to
+light.  It is an easy matter to make the negatively heliotropic or the
+indifferent copepods almost instantly positively heliotropic by adding a
+small but definite amount of carbon-dioxide in the form of carbonated water
+to the water in which the animals are contained.  If the animals are
+contained in 50 cubic centimetres of water it suffices to add from three to
+six cubic centimetres of carbonated water to make all the copepods
+energetically positively heliotropic.  This heliotropism lasts about half
+an hour (probably until all the carbon-dioxide has again diffused into the
+air.)  Similar results may be obtained with any other acid.
+
+The same experiments may be made with another freshwater crustacean, namely
+Daphnia, with this difference, however, that it is as a rule necessary to
+lower the temperature of the water also.  If the water containing the
+Daphniae is cooled and at the same time carbon-dioxide added, the animals
+which were before indifferent to light now become most strikingly
+positively heliotropic.  Marine copepods can be made positively heliotropic
+by the lowering of the temperature alone, or by a sudden increase in the
+concentration of the sea-water.
+
+These data have a bearing upon the depth-migrations of pelagic animals, as
+was pointed out years ago by Theo. T. Groom and the writer.  It is well
+known that many animals living near the surface of the ocean or freshwater
+lakes, have a tendency to migrate upwards towards evening and downwards in
+the morning and during the day.  These periodic motions are determined to a
+large extent, if not exclusively, by the heliotropism of these animals. 
+Since the consumption of carbon-dioxide by the green plants ceases towards
+evening, the tension of this gas in the water must rise and this must have
+the effect of inducing positive heliotropism or increasing its intensity. 
+At the same time the temperature of the water near the surface is lowered
+and this also increases the positive heliotropism in the organisms.
+
+The faint light from the sky is sufficient to cause animals which are in a
+high degree positively heliotropic to move vertically upwards towards the
+light, as experiments with such pelagic animals, e.g. copepods, have shown. 
+When, in the morning, the absorption of carbon-dioxide by the green algae
+begins again and the temperature of the water rises, the animals lose their
+positive heliotropism, and slowly sink down or become negatively
+heliotropic and migrate actively downwards.
+
+These experiments have also a bearing upon the problem of the inheritance
+of instincts.  The character which is transmitted in this case is not the
+tendency to migrate periodically upwards and downwards, but the positive
+heliotropism.  The tendency to migrate is the outcome of the fact that
+periodically varying external conditions induce a periodic change in the
+sense and intensity of the heliotropism of these animals.  It is of course
+immaterial for the result, whether the carbon-dioxide or any other acid
+diffuse into the animal from the outside or whether they are produced
+inside in the tissue cells of the animals.  Davenport and Cannon found that
+Daphniae, which at the beginning of the experiment, react sluggishly to
+light react much more quickly after they have been made to go to the light
+a few times.  The writer is inclined to attribute this result to the effect
+of acids, e.g. carbon-dioxide, produced in the animals themselves in
+consequence of their motion.  A similar effect of the acids was shown by
+A.D. Waller in the case of the response of nerve to stimuli.
+
+The writer observed many years ago that winged male and female ants are
+positively helioptropic and that their heliotropic sensitiveness increases
+and reaches its maximum towards the period of nuptial flight.  Since the
+workers show no heliotropism it looks as if an internal secretion from the
+sexual glands were the cause of their heliotropic sensitiveness.  V.
+Kellogg has observed that bees also become intensely positively heliotropic
+at the period of their wedding flight, in fact so much so that by letting
+light fall into the observation hive from above, the bees are prevented
+from leaving the hive through the exit at the lower end.
+
+We notice also the reverse phenomenon, namely, that chemical changes
+produced in the animal destroy its heliotropism.  The caterpillars of
+Porthesia chrysorrhoea are very strongly positively heliotropic when they
+are first aroused from their winter sleep.  This heliotropic sensitiveness
+lasts only as long as they are not fed.  If they are kept permanently
+without food they remain permanently positively heliotropic until they die
+from starvation.  It is to be inferred that as soon as these animals take
+up food, a substance or substances are formed in their bodies which
+diminish or annihilate their heliotropic sensitiveness.
+
+The heliotropism of animals is identical with the heliotropism of plants. 
+The writer has shown that the experiments on the effect of acids on the
+heliotropism of copepods can be repeated with the same result in Volvox. 
+It is therefore erroneous to try to explain these heliotropic reactions of
+animals on the basis of peculiarities (e.g. vision) which are not found in
+plants.
+
+We may briefly discuss the question of the transmission through the sex
+cells of such instincts as are based upon heliotropism.  This problem
+reduces itself simply to that of the method whereby the gametes transmit
+heliotropism to the larvae or to the adult.  The writer has expressed the
+idea that all that is necessary for this transmission is the presence in
+the eyes (or in the skin) of the animal of a photo-sensitive substance. 
+For the transmission of this the gametes need not contain anything more
+than a catalyser or ferment for the synthesis of the photo-sensitive
+substance in the body of the animal.  What has been said in regard to
+animal heliotropism might, if space permitted, be extended, mutatis
+mutandis, to geotropism and stereotropism.
+
+(c)  THE TROPIC REACTIONS OF CERTAIN TISSUE-CELLS AND THE MORPHOGENETIC
+EFFECTS OF THESE REACTIONS.
+
+Since plant-cells show heliotropic reactions identical with those of
+animals, it is not surprising that certain tissue-cells also show reactions
+which belong to the class of tropisms.  These reactions of tissue-cells are
+of special interest by reason of their bearing upon the inheritance of
+morphological characters.  An example of this is found in the tiger-like
+marking of the yolk-sac of the embryo of Fundulus and in the marking of the
+young fish itself.  The writer found that the former is entirely, and the
+latter at least in part, due to the creeping of the chromatophores upon the
+blood-vessels.  The chromatophores are at first scattered irregularly over
+the yolk-sac and show their characteristic ramifications.  There is at that
+time no definite relation between blood-vessels and chromatophores.  As
+soon as a ramification of a chromatophore comes in contact with a blood-
+vessel the whole mass of the chromatophore creeps gradually on the blood-
+vessel and forms a complete sheath around the vessel, until finally all the
+chromatophores form a sheath around the vessels and no more pigment cells
+are found in the meshes between the vessels.  Nobody who has not actually
+watched the process of the creeping of the chromatophores upon the blood-
+vessels would anticipate that the tiger-like colouration of the yolk-sac in
+the later stages of the development was brought about in this way.  Similar
+facts can be observed in regard to the first marking of the embryo itself. 
+The writer is inclined to believe that we are here dealing with a case of
+chemotropism, and that the oxygen of the blood may be the cause of the
+spreading of the chromatophores around the blood-vessels.  Certain
+observations seem to indicate the possibility that in the adult the
+chromatophores have, in some forms at least, a more rigid structure and are
+prevented from acting in the way indicated.  It seems to the writer that
+such observations as those made on Fundulus might simplify the problem of
+the hereditary transmission of certain markings.
+
+Driesch has found that a tropism underlies the arrangement of the skeleton
+in the pluteus larvae of the sea-urchin.  The position of this skeleton is
+predetermined by the arrangement of the mesenchyme cells, and Driesch has
+shown that these cells migrate actively to the place of their destination,
+possibly led there under the influence of certain chemical substances. 
+When Driesch scattered these cells mechanically before their migration,
+they nevertheless reached their destination.
+
+In the developing eggs of insects the nuclei, together with some cytoplasm,
+migrate to the periphery of the egg.  Herbst pointed out that this might be
+a case of chemotropism, caused by the oxygen surrounding the egg.  The
+writer has expressed the opinion that the formation of the blastula may be
+caused generally by a tropic reaction of the blastomeres, the latter being
+forced by an outside influence to creep to the surface of the egg.
+
+These examples may suffice to indicate that the arrangement of definite
+groups of cells and the morphological effects resulting therefrom may be
+determined by forces lying outside the cells.  Since these forces are
+ubiquitous and constant it appears as if we were dealing exclusively with
+the influence of a gamete; while in reality all that it is necessary for
+the gamete to transmit is a certain form of irritability.
+
+(d)  FACTORS WHICH DETERMINE PLACE AND TIME FOR THE DEPOSITION OF EGGS.
+
+For the preservation of species the instinct of animals to lay their eggs
+in places in which the young larvae find their food and can develop is of
+paramount importance.  A simple example of this instinct is the fact that
+the common fly lays its eggs on putrid material which serves as food for
+the young larvae.  When a piece of meat and of fat of the same animal are
+placed side by side, the fly will deposit its eggs upon the meat on which
+the larvae can grow, and not upon the fat, on which they would starve. 
+Here we are dealing with the effect of a volatile nitrogenous substance
+which reflexly causes the peristaltic motions for the laying of the egg in
+the female fly.
+
+Kammerer has investigated the conditions for the laying of eggs in two
+forms of salamanders, e.g. Salamandra atra and S. maculosa.  In both forms
+the eggs are fertilised in the body and begin to develop in the uterus. 
+Since there is room only for a few larvae in the uterus, a large number of
+eggs perish and this number is the greater the longer the period of
+gestation.  It thus happens that when the animals retain their eggs a long
+time, very few young ones are born; and these are in a rather advanced
+stage of development, owing to the long time which elapsed since they were
+fertilised.  When the animal lays its eggs comparatively soon after
+copulation, many eggs (from 12 to 72) are produced and the larvae are of
+course in an early stage of development.  In the early stage the larvae
+possess gills and can therefore live in water, while in later stages they
+have no gills and breathe through their lungs.  Kammerer showed that both
+forms of Salamandra can be induced to lay their eggs early or late,
+according to the physical conditions surrounding them.  If they are kept in
+water or in proximity to water and in a moist atmosphere they have a
+tendency to lay their eggs earlier and a comparatively high temperature
+enhances the tendency to shorten the period of gestation.  If the
+salamanders are kept in comparative dryness they show a tendency to lay
+their eggs rather late and a low temperature enhances this tendency.
+
+Since Salamandra atra is found in rather dry alpine regions with a
+relatively low temperature and Salamandra maculosa in lower regions with
+plenty of water and a higher temperature, the fact that S. atra bears young
+which are already developed and beyond the stage of aquatic life, while S.
+maculosa bears young ones in an earlier stage, has been termed adaptation. 
+Kammerer's experiments, however, show that we are dealing with the direct
+effects of definite outside forces.  While we may speak of adaptation when
+all or some of the variables which determine a reaction are unknown, it is
+obviously in the interest of further scientific progress to connect cause
+and effect directly whenever our knowledge allows us to do so.
+
+VII.  CONCLUDING REMARKS.
+
+The discovery of De Vries, that new species may arise by mutation and the
+wide if not universal applicability of Mendel's Law to phenomena of
+heredity, as shown especially by Bateson and his pupils, must, for the time
+being, if not permanently, serve as a basis for theories of evolution. 
+These discoveries place before the experimental biologist the definite task
+of producing mutations by physico-chemical means.  It is true that certain
+authors claim to have succeeded in this, but the writer wishes to apologise
+to these authors for his inability to convince himself of the validity of
+their claims at the present moment.  He thinks that only continued breeding
+of these apparent mutants through several generations can afford convincing
+evidence that we are here dealing with mutants rather than with merely
+pathological variations.
+
+What was said in regard to the production of new species by physico-
+chemical means may be repeated with still more justification in regard to
+the second problem of transformation, namely the making of living from
+inanimate matter.  The purely morphological imitations of bacteria or cells
+which physicists have now and then proclaimed as artificially produced
+living beings; or the plays on words by which, e.g. the regeneration of
+broken crystals and the regeneration of lost limbs by a crustacean were
+declared identical, will not appeal to the biologist.  We know that growth
+and development in animals and plants are determined by definite although
+complicated series of catenary chemical reactions, which result in the
+synthesis of a DEFINITE compound or group of compounds, namely, NUCLEINS.
+
+The nucleins have the peculiarity of acting as ferments or enzymes for
+their own synthesis.  Thus a given type of nucleus will continue to
+synthesise other nuclein of its own kind.  This determines the continuity
+of a species; since each species has, probably, its own specific nuclein or
+nuclear material.  But it also shows us that whoever claims to have
+succeeded in making living matter from inanimate will have to prove that he
+has succeeded in producing nuclein material which acts as a ferment for its
+own synthesis and thus reproduces itself.  Nobody has thus far succeeded in
+this, although nothing warrants us in taking it for granted that this task
+is beyond the power of science.
+
+XV.  THE VALUE OF COLOUR IN THE STRUGGLE FOR LIFE.
+
+By E.B. POULTON.
+Hope Professor of Zoology in the University of Oxford.
+
+INTRODUCTION.
+
+The following pages have been written almost entirely from the historical
+stand-point.  Their principal object has been to give some account of the
+impressions produced on the mind of Darwin and his great compeer Wallace by
+various difficult problems suggested by the colours of living nature.  In
+order to render the brief summary of Darwin's thoughts and opinions on the
+subject in any way complete, it was found necessary to say again much that
+has often been said before.  No attempt has been made to display as a whole
+the vast contribution of Wallace; but certain of its features are
+incidentally revealed in passages quoted from Darwin's letters.  It is
+assumed that the reader is familiar with the well-known theories of
+Protective Resemblance, Warning Colours, and Mimicry both Batesian and
+Mullerian.  It would have been superfluous to explain these on the present
+occasion; for a far more detailed account than could have been attempted in
+these pages has recently appeared.  (Poulton, "Essays on Evolution" Oxford,
+1908, pages 293-382.)  Among the older records I have made a point of
+bringing together the principal observations scattered through the note-
+books and collections of W.J. Burchell.  These have never hitherto found a
+place in any memoir dealing with the significance of the colours of
+animals.
+
+INCIDENTAL COLOURS.
+
+Darwin fully recognised that the colours of living beings are not
+necessarily of value as colours, but that they may be an incidental result
+of chemical or physical structure.  Thus he wrote to T. Meehan, Oct. 9,
+1874:  "I am glad that you are attending to the colours of dioecious
+flowers; but it is well to remember that their colours may be as
+unimportant to them as those of a gall, or, indeed, as the colour of an
+amethyst or ruby is to these gems."  ("More Letters of Charles Darwin",
+Vol. I. pages 354, 355.  See also the admirable account of incidental
+colours in "Descent of Man" (2nd edition), 1874, pages 261, 262.)
+
+Incidental colours remain as available assets of the organism ready to be
+turned to account by natural selection.  It is a probable speculation that
+all pigmentary colours were originally incidental; but now and for immense
+periods of time the visible tints of animals have been modified and
+arranged so as to assist in the struggle with other organisms or in
+courtship.  The dominant colouring of plants, on the other hand, is an
+essential element in the paramount physiological activity of chlorophyll. 
+In exceptional instances, however, the shapes and visible colours of plants
+may be modified in order to promote concealment.
+
+TELEOLOGY AND ADAPTATION.
+
+In the department of Biology which forms the subject of this essay, the
+adaptation of means to an end is probably more evident than in any other;
+and it is therefore of interest to compare, in a brief introductory
+section, the older with the newer teleological views.
+
+The distinctive feature of Natural Selection as contrasted with other
+attempts to explain the process of Evolution is the part played by the
+struggle for existence.  All naturalists in all ages must have known
+something of the operations of "Nature red in tooth and claw"; but it was
+left for this great theory to suggest that vast extermination is a
+necessary condition of progress, and even of maintaining the ground already
+gained.
+
+Realising that fitness is the outcome of this fierce struggle, thus turned
+to account for the first time, we are sometimes led to associate the
+recognition of adaptation itself too exclusively with Natural Selection. 
+Adaptation had been studied with the warmest enthusiasm nearly forty years
+before this great theory was given to the scientific world, and it is
+difficult now to realise the impetus which the works of Paley gave to the
+study of Natural History.  That they did inspire the naturalists of the
+early part of the last century is clearly shown in the following passages.
+
+In the year 1824 the Ashmolean Museum at Oxford was intrusted to the care
+of J.S. Duncan of New College.  He was succeeded in this office by his
+brother, P.B. Duncan, of the same College, author of a History of the
+Museum, which shows very clearly the influence of Paley upon the study of
+nature, and the dominant position given to his teachings:  "Happily at this
+time (1824) a taste for the study of natural history had been excited in
+the University by Dr Paley's very interesting work on Natural Theology, and
+the very popular lectures of Dr Kidd on Comparative Anatomy, and Dr
+Buckland on Geology."  In the arrangement of the contents of the Museum the
+illustration of Paley's work was given the foremost place by J.S. Duncan: 
+"The first division proposes to familiarize the eye to those relations of
+all natural objects which form the basis of argument in Dr Paley's Natural
+Theology; to induce a mental habit of associating the view of natural
+phenomena with the conviction that they are the media of Divine
+manifestation; and by such association to give proper dignity to every
+branch of natural science."  ((From "History and Arrangement of the
+Ashmolean Museum" by P.B. Duncan:  see pages vi, vii of "A Catalogue of the
+Ashmolean Museum", Oxford, 1836.)
+
+The great naturalist, W.J. Burchell, in his classical work shows the same
+recognition of adaptation in nature at a still earlier date.  Upon the
+subject of collections he wrote ("Travels in the Interior of Southern
+Africa", London, Vol. I. 1822, page 505.  The references to Burchell's
+observations in the present essay are adapted from the author's article in
+"Report of the British and South African Associations", 1905, Vol. III.
+pages 57-110.):  "It must not be supposed that these charms (the pleasures
+of Nature) are produced by the mere discovery of new objects:  it is the
+harmony with which they have been adapted by the Creator to each other, and
+to the situations in which they are found, which delights the observer in
+countries where Art has not yet introduced her discords."  The remainder of
+the passage is so admirable that I venture to quote it:  "To him who is
+satisfied with amassing collections of curious objects, simply for the
+pleasure of possessing them, such objects can afford, at best, but a
+childish gratification, faint and fleeting; while he who extends his view
+beyond the narrow field of nomenclature, beholds a boundless expanse, the
+exploring of which is worthy of the philosopher, and of the best talents of
+a reasonable being."
+
+On September 14, 1811, Burchell was at Zand Valley (Vlei), or Sand Pool, a
+few miles south-west of the site of Prieska, on the Orange River.  Here he
+found a Mesembryanthemum (M. turbiniforme, now M. truncatum) and also a
+"Gryllus" (Acridian), closely resembling the pebbles with which their
+locality was strewn.  He says of both of these, "The intention of Nature,
+in these instances, seems to have been the same as when she gave to the
+Chameleon the power of accommodating its color, in a certain degree, to
+that of the object nearest to it, in order to compensate for the deficiency
+of its locomotive powers.  By their form and colour, this insect may pass
+unobserved by those birds, which otherwise would soon extirpate a species
+so little able to elude its pursuers, and this juicy little
+Mesembryanthemum may generally escape the notice of cattle and wild
+animals."  (Loc. cit. pages 310, 311.  See Sir William Thiselton-Dyer
+"Morphological Notes", XI.; "Protective Adaptations", I.; "Annals of
+Botany", Vol. XX. page 124.  In plates VII., VIII. and IX. accompanying
+this article the author represents the species observed by Burchell,
+together with others in which analogous adaptations exist.  He writes: 
+"Burchell was clearly on the track on which Darwin reached the goal.  But
+the time had not come for emancipation from the old teleology.  This,
+however, in no respect detracts from the merit or value of his work.  For,
+as Huxley has pointed out ("Life and Letters of Thomas Henry Huxley",
+London, 1900, I. page 457), the facts of the old teleology are immediately
+transferable to Darwinism, which simply supplies them with a natural in
+place of a supernatural explanation.")  Burchell here seems to miss, at
+least in part, the meaning of the relationship between the quiescence of
+the Acridian and its cryptic colouring.  Quiescence is an essential element
+in the protective resemblance to a stone--probably even more indispensable
+than the details of the form and colouring.  Although Burchell appears to
+overlook this point he fully recognised the community between protection by
+concealment and more aggressive modes of defence; for, in the passage of
+which a part is quoted above, he specially refers to some earlier remarks
+on page 226 of his Vol. I.  We here find that even when the oxen were
+resting by the Juk rivier (Yoke river), on July 19, 1811, Burchell observed
+"Geranium spinosum, with a fleshy stem and large white flowers...; and a
+succulent species of Pelargonium...so defended by the old panicles, grown
+to hard woody thorns, that no cattle could browze upon it."  He goes on to
+say, "In this arid country, where every juicy vegetable would soon be eaten
+up by the wild animals, the Great Creating Power, with all-provident
+wisdom, has given to such plants either an acrid or poisonous juice, or
+sharp thorns, to preserve the species from annihilation..."  All these
+modes of defence, especially adapted to a desert environment, have since
+been generally recognised, and it is very interesting to place beside
+Burchell's statement the following passage from a letter written by Darwin,
+Aug. 7, 1868, to G.H. Lewes;  "That Natural Selection would tend to produce
+the most formidable thorns will be admitted by every one who has observed
+the distribution in South America and Africa (vide Livingstone) of thorn-
+bearing plants, for they always appear where the bushes grow isolated and
+are exposed to the attacks of mammals.  Even in England it has been noticed
+that all spine-bearing and sting-bearing plants are palatable to
+quadrupeds, when the thorns are crushed."  ("More Letters", I. page 308.)
+
+ADAPTATION AND NATURAL SELECTION.
+
+I have preferred to show the influence of the older teleology upon Natural
+History by quotations from a single great and insufficiently appreciated
+naturalist.  It might have been seen equally well in the pages of Kirby and
+Spence and those of many other writers.  If the older naturalists who
+thought and spoke with Burchell of "the intention of Nature" and the
+adaptation of beings "to each other, and to the situations in which they
+are found," could have conceived the possibility of evolution, they must
+have been led, as Darwin was, by the same considerations to Natural
+Selection.  This was impossible for them, because the philosophy which they
+followed contemplated the phenomena of adaptation as part of a static
+immutable system.  Darwin, convinced that the system is dynamic and
+mutable, was prevented by these very phenomena from accepting anything
+short of the crowning interpretation offered by Natural Selection.  ("I had
+always been much struck by such adaptations (e.g. woodpecker and tree-frog
+for climbing, seeds for dispersal), and until these could be explained it
+seemed to me almost useless to endeavour to prove by indirect evidence that
+species have been modified."  "Autobiography" in "Life and Letters of
+Charles Darwin", Vol. I. page 82.  The same thought is repeated again and
+again in Darwin's letters to his friends.  It is forcibly urged in the
+Introduction to the "Origin" (1859), page 3.)  And the birth of Darwin's
+unalterable conviction that adaptation is of dominant importance in the
+organic world,--a conviction confirmed and ever again confirmed by his
+experience as a naturalist--may probably be traced to the influence of the
+great theologian.  Thus Darwin, speaking of his Undergraduate days, tells
+us in his "Autobiography" that the logic of Paley's "Evidences of
+Christianity" and "Moral Philosophy" gave him as much delight as did
+Euclid.
+
+"The careful study of these works, without attempting to learn any part by
+rote, was the only part of the academical course which, as I then felt and
+as I still believe, was of the least use to me in the education of my mind.
+I did not at that time trouble myself about Paley's premises; and taking
+these on trust, I was charmed and convinced by the long line of
+argumentation."  ("Life and Letters", I. page 47.)
+
+When Darwin came to write the "Origin" he quoted in relation to Natural
+Selection one of Paley's conclusions.  "No organ will be formed, as Paley
+has remarked, for the purpose of causing pain or for doing an injury to its
+possessor."  ("Origin of Species" (1st edition) 1859, page 201.)
+
+The study of adaptation always had for Darwin, as it has for many, a
+peculiar charm.  His words, written Nov. 28, 1880, to Sir W. Thiselton-
+Dyer, are by no means inapplicable to-day:  "Many of the Germans are very
+contemptuous about making out use of organs; but they may sneer the souls
+out of their bodies, and I for one shall think it the most interesting part
+of natural history."  ("More Letters" II. page 428.)
+
+PROTECTIVE AND AGGRESSIVE RESEMBLANCE:  PROCRYPTIC AND ANTICRYPTIC
+COLOURING.
+
+Colouring for the purpose of concealment is sometimes included under the
+head Mimicry, a classification adopted by H.W. Bates in his classical
+paper.  Such an arrangement is inconvenient, and I have followed Wallace in
+keeping the two categories distinct.
+
+The visible colours of animals are far more commonly adapted for Protective
+Resemblance than for any other purpose.  The concealment of animals by
+their colours, shapes and attitudes, must have been well known from the
+period at which human beings first began to take an intelligent interest in
+Nature.  An interesting early record is that of Samuel Felton, who (Dec. 2,
+1763) figured and gave some account of an Acridian (Phyllotettix) from
+Jamaica.  Of this insect he says "THE THORAX is like a leaf that is raised
+perpendicularly from the body."  ("Phil. Trans. Roy. Soc." Vol. LIV. Tab.
+VI. page 55.)
+
+Both Protective and Aggressive Resemblances were appreciated and clearly
+explained by Erasmus Darwin in 1794:  "The colours of many animals seem
+adapted to their purposes of concealing themselves either to avoid danger,
+or to spring upon their prey."  ("Zoonomia", Vol. I. page 509, London,
+1794.)
+
+Protective Resemblance of a very marked and beautiful kind is found in
+certain plants, inhabitants of desert areas.  Examples observed by Burchell
+almost exactly a hundred years ago have already been mentioned.  In
+addition to the resemblance to stones Burchell observed, although he did
+not publish the fact, a South African plant concealed by its likeness to
+the dung of birds.  (Sir William Thiselton-Dyer has suggested the same
+method of concealment ("Annals of Botany", Vol. XX. page 123).  Referring
+to Anacampseros papyracea, figured on plate IX., the author says of its
+adaptive resemblance:  "At the risk of suggesting one perhaps somewhat far-
+fetched, I must confess that the aspect of the plant always calls to my
+mind the dejecta of some bird, and the more so owing to the whitening of
+the branches towards the tips" (loc. cit. page 126).  The student of
+insects, who is so familiar with this very form of protective resemblance
+in larvae, and even perfect insects, will not be inclined to consider the
+suggestion far-fetched.)  The observation is recorded in one of the
+manuscript journals kept by the great explorer during his journey.  I owe
+the opportunity of studying it to the kindness of Mr Francis A. Burchell of
+the Rhodes University College, Grahamstown.  The following account is given
+under the date July 5, 1812, when Burchell was at the Makkwarin River,
+about half-way between the Kuruman River and Litakun the old capital of the
+Bachapins (Bechuanas):  "I found a curious little Crassula (not in flower)
+so snow white, that I should never has (have) distinguished it from the
+white limestones...It was an inch high and a little branchy,...and was at
+first mistaken for the dung of birds of the passerine order.  I have often
+had occasion to remark that in stony place(s) there grow many small
+succulent plants and abound insects (chiefly Grylli) which have exactly the
+same colour as the ground and must for ever escape observation unless a
+person sit on the ground and observe very attentively."
+
+The cryptic resemblances of animals impressed Darwin and Wallace in very
+different degrees, probably in part due to the fact that Wallace's tropical
+experiences were so largely derived from the insect world, in part to the
+importance assigned by Darwin to Sexual Selection "a subject which had
+always greatly interested me," as he says in his "Autobiography", ("Life
+and Letters", Vol. I. page 94.)  There is no reference to Cryptic
+Resemblance in Darwin's section of the Joint Essay, although he gives an
+excellent short account of Sexual Selection (see page 295).  Wallace's
+section on the other hand contains the following statement:  "Even the
+peculiar colours of many animals, especially insects, so closely resembling
+the soil or the leaves or the trunks on which they habitually reside, are
+explained on the same principle; for though in the course of ages varieties
+of many tints may have occurred, YET THOSE RACES HAVING COLOURS BEST
+ADAPTED TO CONCEALMENT FROM THEIR ENEMIES WOULD INEVITABLY SURVIVE THE
+LONGEST."  ("Journ. Proc. Linn. Soc." Vol. III. 1859, page 61.  The italics
+are Wallace's.)
+
+It would occupy too much space to attempt any discussion of the difference
+between the views of these two naturalists, but it is clear that Darwin,
+although fully believing in the efficiency of protective resemblance and
+replying to St George Mivart's contention that Natural Selection was
+incompetent to produce it ("Origin" (6th edition) London, 1872, pages 181,
+182; see also page 66.), never entirely agreed with Wallace's estimate of
+its importance.  Thus the following extract from a letter to Sir Joseph
+Hooker, May 21, 1868, refers to Wallace:  "I find I must (and I always
+distrust myself when I differ from him) separate rather widely from him all
+about birds' nests and protection; he is riding that hobby to death." 
+("More Letters", I. page 304.)  It is clear from the account given in "The
+Descent of Man", (London, 1874, pages 452-458.  See also "Life and
+Letters", III. pages 123-125, and "More Letters", II. pages 59-63, 72-74,
+76-78, 84-90, 92, 93.), that the divergence was due to the fact that Darwin
+ascribed more importance to Sexual Selection than did Wallace, and Wallace
+more importance to Protective Resemblance than Darwin.  Thus Darwin wrote
+to Wallace, Oct. 12 and 13, 1867:  "By the way, I cannot but think that you
+push protection too far in some cases, as with the stripes on the tiger." 
+("More Letters", I. page 283.)  Here too Darwin was preferring the
+explanation offered by Sexual Selection ("Descent of Man" (2nd edition)
+1874, pages 545, 546.), a preference which, considering the relation of the
+colouring of the lion and tiger to their respective environments, few
+naturalists will be found to share.  It is also shown that Darwin
+contemplated the possibility of cryptic colours such as those of Patagonian
+animals being due to sexual selection influenced by the aspect of
+surrounding nature.
+
+Nearly a year later Darwin in his letter of May 5, 1868?, expressed his
+agreement with Wallace's views:  "Expect that I should put sexual selection
+as an equal, or perhaps as even a more important agent in giving colour
+than Natural Selection for protection."  ("More Letters", II. pages 77,
+78.)  The conclusion expressed in the above quoted passage is opposed by
+the extraordinary development of Protective Resemblance in the immature
+stages of animals, especially insects.
+
+It must not be supposed, however, that Darwin ascribed an unimportant role
+to Cryptic Resemblances, and as observations accumulated he came to
+recognise their efficiency in fresh groups of the animal kingdom.  Thus he
+wrote to Wallace, May 5, 1867:  "Haeckel has recently well shown that the
+transparency and absence of colour in the lower oceanic animals, belonging
+to the most different classes, may be well accounted for on the principle
+of protection."  ("More Letters", II. page 62.  See also "Descent of Man",
+page 261.)  Darwin also admitted the justice of Professor E.S. Morse's
+contention that the shells of molluscs are often adaptively coloured. 
+("More Letters", II. page 95.)  But he looked upon cryptic colouring and
+also mimicry as more especially Wallace's departments, and sent to him and
+to Professor Meldola observations and notes bearing upon these subjects. 
+Thus the following letter given to me by Dr A.R. Wallace and now, by kind
+permission, published for the first time, accompanied a photograph of the
+chrysalis of Papilio sarpedon choredon, Feld., suspended from a leaf of its
+food-plant:
+
+July 9th,
+Down, Beckenham, Kent.
+
+My Dear Wallace,
+
+Dr G. Krefft has sent me the enclosed from Sydney.  A nurseryman saw a
+caterpillar feeding on a plant and covered the whole up, but when he
+searched for the cocoon (pupa), was long before he could find it, so good
+was its imitation in colour and form to the leaf to which it was attached.
+I hope that the world goes well with you.  Do not trouble yourself by
+acknowledging this.
+
+Ever yours
+
+Ch. Darwin.
+
+Another deeply interesting letter of Darwin's bearing upon protective
+resemblance, has only recently been shown to me by my friend Professor E.B.
+Wilson, the great American Cytologist.  With his kind consent and that of
+Mr Francis Darwin, this letter, written four months before Darwin's death
+on April 19, 1882, is reproduced here (The letter is addressed:  "Edmund B.
+Wilson, Esq., Assistant in Biology, John Hopkins University, Baltimore Md,
+U. States.":
+
+December 21, 1881.
+
+Dear Sir,
+
+I thank you much for having taken so much trouble in describing fully your
+interesting and curious case of mimickry.
+
+I am in the habit of looking through many scientific Journals, and though
+my memory is now not nearly so good as it was, I feel pretty sure that no
+such case as yours has been described (amongst the nudibranch) molluscs. 
+You perhaps know the case of a fish allied to Hippocampus, (described some
+years ago by Dr Gunther in "Proc. Zoolog. Socy.") which clings by its tail
+to sea-weeds, and is covered with waving filaments so as itself to look
+like a piece of the same sea-weed.  The parallelism between your and Dr
+Gunther's case makes both of them the more interesting; considering how far
+a fish and a mollusc stand apart.  It would be difficult for anyone to
+explain such cases by the direct action of the environment.--I am glad that
+you intend to make further observations on this mollusc, and I hope that
+you will give a figure and if possible a coloured figure.
+
+With all good wishes from an old brother naturalist,
+
+I remain, Dear Sir,
+
+Yours faithfully,
+
+Charles Darwin.
+
+Professor E.B. Wilson has kindly given the following account of the
+circumstances under which he had written to Darwin:  "The case to which
+Darwin's letter refers is that of the nudibranch mollusc Scyllaea, which
+lives on the floating Sargassum and shows a really astonishing resemblance
+to the plant, having leaf-shaped processes very closely similar to the
+fronds of the sea-weed both in shape and in colour.  The concealment of the
+animal may be judged from the fact that we found the animal quite by
+accident on a piece of Sargassum that had been in a glass jar in the
+laboratory for some time and had been closely examined in the search for
+hydroids and the like without disclosing the presence upon it of two large
+specimens of the Scyllaea (the animal, as I recall it, is about two inches
+long).  It was first detected by its movements alone, by someone (I think a
+casual visitor to the laboratory) who was looking closely at the Sargassum
+and exclaimed 'Why, the sea-weed is moving its leaves'!  We found the
+example in the summer of 1880 or 1881 at Beaufort, N.C., where the Johns
+Hopkins laboratory was located for the time being.  It must have been seen
+by many others, before or since.
+
+"I wrote and sent to Darwin a short description of the case at the
+suggestion of Brooks, with whom I was at the time a student.  I was, of
+course, entirely unknown to Darwin (or to anyone else) and to me the
+principal interest of Darwin's letter is the evidence that it gives of his
+extraordinary kindness and friendliness towards an obscure youngster who
+had of course absolutely no claim upon his time or attention.  The little
+incident made an indelible impression upon my memory and taught me a lesson
+that was worth learning."
+
+VARIABLE PROTECTIVE RESEMBLANCE.
+
+The wonderful power of rapid colour adjustment possessed by the cuttle-fish
+was observed by Darwin in 1832 at St Jago, Cape de Verd Islands, the first
+place visited during the voyage of the "Beagle".  From Rio he wrote to
+Henslow, giving the following account of his observations, May 18, 1832: 
+"I took several specimens of an Octopus which possessed a most marvellous
+power of changing its colours, equalling any chameleon, and evidently
+accommodating the changes to the colour of the ground which it passed over.
+Yellowish green, dark brown, and red, were the prevailing colours; this
+fact appears to be new, as far as I can find out."  ("Life and Letters", I.
+pages 235, 236.  See also Darwin's "Journal of Researches", 1876, pages 6-
+8, where a far more detailed account is given together with a reference to
+"Encycl. of Anat. and Physiol.")
+
+Darwin was well aware of the power of individual colour adjustment, now
+known to be possessed by large numbers of lepidopterous pupae and larvae. 
+An excellent example was brought to his notice by C.V. Riley ("More
+Letters" II, pages 385, 386.), while the most striking of the early results
+obtained with the pupae of butterflies--those of Mrs M.E. Barber upon
+Papilio nireus--was communicated by him to the Entomological Society of
+London.  ("Trans. Ent. Soc. Lond." 1874, page 519.  See also "More
+Letters", II. page 403.)
+
+It is also necessary to direct attention to C.W. Beebe's ("Zoologica:  N.Y.
+Zool. Soc." Vol. I. No. 1, Sept. 25, 1907: "Geographic variation in birds
+with especial reference to the effects of humidity".) recent discovery that
+the pigmentation of the plumage of certain birds is increased by
+confinement in a superhumid atmosphere.  In Scardafella inca, on which the
+most complete series of experiments was made, the changes took place only
+at the moults, whether normal and annual or artificially induced at shorter
+periods.  There was a corresponding increase in the choroidal pigment of
+the eye.  At a certain advanced stage of feather pigmentation a brilliant
+iridescent bronze or green tint made its appearance on those areas where
+iridescence most often occurs in allied genera.  Thus in birds no less than
+in insects, characters previously regarded as of taxonomic value, can be
+evoked or withheld by the forces of the environment.
+
+WARNING OR APOSEMATIC COLOURS.
+
+From Darwin's description of the colours and habits it is evident that he
+observed, in 1833, an excellent example of warning colouring in a little
+South American toad (Phryniscus nigricans).  He described it in a letter to
+Henslow, written from Monte Video, Nov. 24, 1832:  "As for one little toad,
+I hope it may be new, that it may be christened 'diabolicus.'  Milton must
+allude to this very individual when he talks of 'squat like a toad'; its
+colours are by Werner ("Nomenclature of Colours", 1821) ink black,
+vermilion red and buff orange."  ("More Letters", I. page 12.)  In the
+"Journal of Researches" (1876, page 97.) its colours are described as
+follows:  "If we imagine, first, that it had been steeped in the blackest
+ink, and then, when dry, allowed to crawl over a board, freshly painted
+with the brightest vermilion, so as to colour the soles of its feet and
+parts of its stomach, a good idea of its appearance will be gained." 
+"Instead of being nocturnal in its habits, as other toads are, and living
+in damp obscure recesses, it crawls during the heat of the day about the
+dry sand-hillocks and arid plains,..."  The appearance and habits recall T.
+Belt's well-known description of the conspicuous little Nicaraguan frog
+which he found to be distasteful to a duck.  ("The Naturalist in Nicaragua"
+(2nd edition) London, 1888, page 321.)
+
+The recognition of the Warning Colours of caterpillars is due in the first
+instance to Darwin, who, reflecting on Sexual Selection, was puzzled by the
+splendid colours of sexually immature organisms.  He applied to Wallace
+"who has an innate genius for solving difficulties."  ("Descent of Man",
+page 325.  On this and the following page an excellent account of the
+discovery will be found, as well as in Wallace's "Natural Selection",
+London, 1875, pages 117-122.)  Darwin's original letter exists ("Life and
+Letters", III. pages 93, 94.), and in it we are told that he had taken the
+advice given by Bates:  "You had better ask Wallace."  After some
+consideration Wallace replied that he believed the colours of conspicuous
+caterpillars and perfect insects were a warning of distastefulness and that
+such forms would be refused by birds.  Darwin's reply ("Life and Letters",
+III. pages 94, 95.) is extremely interesting both for its enthusiasm at the
+brilliancy of the hypothesis and its caution in acceptance without full
+confirmation:
+
+"Bates was quite right; you are the man to apply to in a difficulty.  I
+never heard anything more ingenious than your suggestion, and I hope you
+may be able to prove it true.  That is a splendid fact about the white
+moths (A single white moth which was rejected by young turkeys, while other
+moths were greedily devoured:  "Natural Selection", 1875, page 78.); it
+warms one's very blood to see a theory thus almost proved to be true."
+
+Two years later the hypothesis was proved to hold for caterpillars of many
+kinds by J. Jenner Weir and A.G. Butler, whose observations have since been
+abundantly confirmed by many naturalists.  Darwin wrote to Weir, May 13,
+1869:  "Your verification of Wallace's suggestion seems to me to amount to
+quite a discovery."  ("More Letters", II. page 71 (footnote).)
+
+RECOGNITION OR EPISEMATIC CHARACTERS.
+
+This principle does not appear to have been in any way foreseen by Darwin,
+although he draws special attention to several elements of pattern which
+would now be interpreted by many naturalists as epismes.  He believed that
+the markings in question interfered with the cryptic effect, and came to
+the conclusion that, even when common to both sexes, they "are the result
+of sexual selection primarily applied to the male."  ("Descent of Man",
+page 544.)  The most familiar of all recognition characters was carefully
+explained by him, although here too explained as an ornamental feature now
+equally transmitted to both sexes:  "The hare on her form is a familiar
+instance of concealment through colour; yet this principle partly fails in
+a closely-allied species, the rabbit, for when running to its burrow, it is
+made conspicuous to the sportsman, and no doubt to all beasts of prey, by
+its upturned white tail."  ("Descent of Man", page 542.)
+
+The analogous episematic use of the bright colours of flowers to attract
+insects for effecting cross-fertilisation and of fruits to attract
+vertebrates for effecting dispersal is very clearly explained in the
+"Origin".  (Edition 1872, page 161.  For a good example of Darwin's caution
+in dealing with exceptions see the allusion to brightly coloured fruit in
+"More Letters", II. page 348.)
+
+It is not, at this point, necessary to treat sematic characters at any
+greater length.  They will form the subject of a large part of the
+following section, where the models of Batesian (Pseudaposematic) mimicry
+are considered as well as the Mullerian (Synaposematic) combinations of
+Warning Colours.
+
+MIMICRY,--BATESIAN OR PSEUDAPOSEMATIC, MULLERIAN OR SYNAPOSEMATIC.
+
+The existence of superficial resemblances between animals of various
+degrees of affinity must have been observed for hundreds of years.  Among
+the early examples, the best known to me have been found in the manuscript
+note-books and collections of W.J. Burchell, the great traveller in Africa
+(1810-15) and Brazil (1825-30).  The most interesting of his records on
+this subject are brought together in the following paragraphs.
+
+Conspicuous among well-defended insects are the dark steely or iridescent
+greenish blue fossorial wasps or sand-wasps, Sphex and the allied genera. 
+Many Longicorn beetles mimic these in colour, slender shape of body and
+limbs, rapid movements, and the readiness with which they take to flight. 
+On Dec. 21, 1812, Burchell captured one such beetle (Promeces viridis) at
+Kosi Fountain on the journey from the source of the Kuruman River to
+Klaarwater.  It is correctly placed among the Longicorns in his catalogue,
+but opposite to its number is the comment "Sphex! totus purpureus."
+
+In our own country the black-and-yellow colouring of many stinging insects,
+especially the ordinary wasps, affords perhaps the commonest model for
+mimicry.  It is reproduced with more or less accuracy on moths, flies and
+beetles.  Among the latter it is again a Longicorn which offers one of the
+best-known, although by no means one of the most perfect, examples.  The
+appearance of the well-known "wasp-beetle" (Clytus arietis) in the living
+state is sufficiently suggestive to prevent the great majority of people
+from touching it.  In Burchell's Brazilian collection there is a nearly
+allied species (Neoclytus curvatus) which appears to be somewhat less wasp-
+like than the British beetle.  The specimen bears the number "1188," and
+the date March 27, 1827, when Burchell was collecting in the neighbourhood
+of San Paulo.  Turning to the corresponding number in the Brazilian note-
+book we find this record:  "It runs rapidly like an ichneumon or wasp, of
+which it has the appearance."
+
+The formidable, well-defended ants are as freely mimicked by other insects
+as the sand-wasps, ordinary wasps and bees.  Thus on February 17, 1901, Guy
+A.K. Marshall captured, near Salisbury, Mashonaland, three similar species
+of ants (Hymenoptera) with a bug (Hemiptera) and a Locustid (Orthoptera),
+the two latter mimicking the former.  All the insects, seven in number,
+were caught on a single plant, a small bushy vetch.  ("Trans. Ent. Soc.
+Lond." 1902, page 535, plate XIX. figs. 53-59.)
+
+This is an interesting recent example from South Africa, and large numbers
+of others might be added--the observations of many naturalists in many
+lands; but nearly all of them known since that general awakening of
+interest in the subject which was inspired by the great hypotheses of H.W.
+Bates and Fritz Muller.  We find, however, that Burchell had more than once
+recorded the mimetic resemblance to ants.  An extremely ant-like bug (the
+larva of a species of Alydus) in his Brazilian collection is labelled
+"1141," with the date December 8, 1826, when Burchell was at the Rio das
+Pedras, Cubatao, near Santos.  In the note-book the record is as follows: 
+"1141 Cimex.  I collected this for a Formica."
+
+Some of the chief mimics of ants are the active little hunting spiders
+belonging to the family Attidae.  Examples have been brought forward during
+many recent years, especially by my friends Dr and Mrs Peckham, of
+Milwaukee, the great authorities on this group of Araneae.  Here too we
+find an observation of the mimetic resemblance recorded by Burchell, and
+one which adds in the most interesting manner to our knowledge of the
+subject.  A fragment, all that is now left, of an Attid spider, captured on
+June 30, 1828, at Goyaz, Brazil, bears the following note, in this case on
+the specimen and not in the note-book:  "Black...runs and seems like an ant
+with large extended jaws."  My friend Mr R.I. Pocock, to whom I have
+submitted the specimen, tells me that it is not one of the group of species
+hitherto regarded as ant-like, and he adds, "It is most interesting that
+Burchell should have noticed the resemblance to an ant in its movements. 
+This suggests that the perfect imitation in shape, as well as in movement,
+seen in many species was started in forms of an appropriate size and colour
+by the mimicry of movement alone."  Up to the present time Burchell is the
+only naturalist who has observed an example which still exhibits this
+ancestral stage in the evolution of mimetic likeness.
+
+Following the teachings of his day, Burchell was driven to believe that it
+was part of the fixed and inexorable scheme of things that these strange
+superficial resemblances existed.  Thus, when he found other examples of
+Hemipterous mimics, including one (Luteva macrophthalma) with "exactly the
+manners of a Mantis," he added the sentence, "In the genus Cimex (Linn.)
+are to be found the outward resemblances of insects of many other genera
+and orders" (February 15, 1829).  Of another Brazilian bug, which is not to
+be found in his collection, and cannot therefore be precisely identified,
+he wrote:  "Cimex...Nature seems to have intended it to imitate a Sphex,
+both in colour and the rapid palpitating and movement of the antennae"
+(November 15, 1826).  At the same time it is impossible not to feel the
+conviction that Burchell felt the advantage of a likeness to stinging
+insects and to aggressive ants, just as he recognised the benefits
+conferred on desert plants by spines and by concealment.  Such an
+interpretation of mimicry was perfectly consistent with the theological
+doctrines of his day.  (See Kirby and Spence, "An Introduction to
+Entomology" (1st edition), London, Vol. II. 1817, page 223.)
+
+The last note I have selected from Burchell's manuscript refers to one of
+the chief mimics of the highly protected Lycid beetles.  The whole
+assemblage of African insects with a Lycoid colouring forms a most
+important combination and one which has an interesting bearing upon the
+theories of Bates and Fritz Muller.  This most wonderful set of mimetic
+forms, described in 1902 by Guy A.K. Marshall, is composed of flower-
+haunting beetles belonging to the family Lycidae, and the heterogeneous
+group of varied insects which mimic their conspicuous and simple scheme of
+colouring.  The Lycid beetles, forming the centre or "models" of the whole
+company, are orange-brown in front for about two-thirds of the exposed
+surface, black behind for the remaining third.  They are undoubtedly
+protected by qualities which make them excessively unpalatable to the bulk
+of insect-eating animals.  Some experimental proof of this has been
+obtained by Mr Guy Marshall.  What are the forms which surround them? 
+According to the hypothesis of Bates they would be, at any rate mainly,
+palatable hard-pressed insects which only hold their own in the struggle
+for life by a fraudulent imitation of the trade-mark of the successful and
+powerful Lycidae.  According to Fritz Muller's hypothesis we should expect
+that the mimickers would be highly protected, successful and abundant
+species, which (metaphorically speaking) have found it to their advantage
+to possess an advertisement, a danger-signal, in common with each other,
+and in common with the beetles in the centre of the group.
+
+How far does the constitution of this wonderful combination--the largest
+and most complicated as yet known in all the world--convey to us the idea
+of mimicry working along the lines supposed by Bates or those suggested by
+Muller?  Figures 1 to 52 of Mr Marshall's coloured plate ("Trans. Ent. Soc.
+Lond." 1902, plate XVIII.  See also page 517, where the group is analysed.)
+represent a set of forty-two or forty-three species or forms of insects
+captured in Mashonaland, and all except two in the neighbourhood of
+Salisbury.  The combination includes six species of Lycidae; nine beetles
+of five groups all specially protected by nauseous qualities, Telephoridae,
+Melyridae, Phytophaga, Lagriidae, Cantharidae; six Longicorn beetles; one
+Coprid beetle; eight stinging Hymenoptera; three or four parasitic
+Hymenoptera (Braconidae, a group much mimicked and shown by some
+experiments to be distasteful); five bugs (Hemiptera, a largely unpalatable
+group); three moths (Arctiidae and Zygaenidae, distasteful families); one
+fly.  In fact the whole combination, except perhaps one Phytophagous, one
+Coprid and the Longicorn beetles, and the fly, fall under the hypothesis of
+Muller and not under that of Bates.  And it is very doubtful whether these
+exceptions will be sustained:  indeed the suspicion of unpalatability
+already besets the Longicorns and is always on the heels,--I should say the
+hind tarsi--of a Phytophagous beetle.
+
+This most remarkable group which illustrates so well the problem of mimicry
+and the alternative hypotheses proposed for its solution, was, as I have
+said, first described in 1902.  Among the most perfect of the mimetic
+resemblances in it is that between the Longicorn beetle, Amphidesmus
+analis, and the Lycidae.  It was with the utmost astonishment and pleasure
+that I found this very resemblance had almost certainly been observed by
+Burchell.  A specimen of the Amphidesmus exists in his collection and it
+bears "651."  Turning to the same number in the African Catalogue we find
+that the beetle is correctly placed among the Longicorns, that it was
+captured at Uitenhage on Nov. 18, 1813, and that it was found associated
+with Lycid beetles in flowers ("consocians cum Lycis 78-87 in floribus"). 
+Looking up Nos. 78-87 in the collection and catalogue, three species of
+Lycidae are found, all captured on Nov. 18, 1813, at Uitenhage.  Burchell
+recognised the wide difference in affinity, shown by the distance between
+the respective numbers; for his catalogue is arranged to represent
+relationships.  He observed, what students of mimicry are only just
+beginning to note and record, the coincidence between model and mimic in
+time and space and in habits.  We are justified in concluding that he
+observed the close superficial likeness although he does not in this case
+expressly allude to it.
+
+One of the most interesting among the early observations of superficial
+resemblance between forms remote in the scale of classification was made by
+Darwin himself, as described in the following passage from his letter to
+Henslow, written from Monte Video, Aug. 15, 1832:  "Amongst the lower
+animals nothing has so much interested me as finding two species of
+elegantly coloured true Planaria inhabiting the dewy forest!  The false
+relation they bear to snails is the most extraordinary thing of the kind I
+have ever seen."  ("More Letters", I. page 9.)
+
+Many years later, in 1867, he wrote to Fritz Muller suggesting that the
+resemblance of a soberly coloured British Planarian to a slug might be due
+to mimicry.  ("Life and Letters", III. page 71.)
+
+The most interesting copy of Bates's classical memoir on Mimicry
+("Contributions to an Insect Fauna of the Amazon Valley".  "Trans. Linn.
+Soc."  Vol. XXIII. 1862, page 495.), read before the Linnean Society in
+1861, is that given by him to the man who has done most to support and
+extend the theory.  My kind friend has given that copy to me; it bears the
+inscription:
+
+"Mr A.R. Wallace from his old travelling companion the Author."
+
+Only a year and a half after the publication of the "Origin", we find that
+Darwin wrote to Bates on the subject which was to provide such striking
+evidence of the truth of Natural Selection:  "I am glad to hear that you
+have specially attended to 'mimetic' analogies--a most curious subject; I
+hope you publish on it.  I have for a long time wished to know whether what
+Dr Collingwood asserts is true--that the most striking cases generally
+occur between insects inhabiting the same country."  (The letter is dated
+April 4, 1861.  "More Letters", I. page 183.)
+
+The next letter, written about six months later, reveals the remarkable
+fact that the illustrious naturalist who had anticipated Edward Forbes in
+the explanation of arctic forms on alpine heights ("I was forestalled in
+only one important point, which my vanity has always made me regret,
+namely, the explanation by means of the Glacial period of the presence of
+the same species of plants and of some few animals on distant mountain
+summits and in the arctic regions.  This view pleased me so much that I
+wrote it out in extenso, and I believe that it was read by Hooker some
+years before E. Forbes published his celebrated memoir on the subject.  In
+the very few points in which we differed, I still think that I was in the
+right.  I have never, of course, alluded in print to my having
+independently worked out this view."  "Autobiography, Life and Letters", I.
+page 88.), had also anticipated H.W. Bates in the theory of Mimicry:  "What
+a capital paper yours will be on mimetic resemblances!  You will make quite
+a new subject of it.  I had thought of such cases as a difficulty; and
+once, when corresponding with Dr Collingwood, I thought of your
+explanation; but I drove it from my mind, for I felt that I had not
+knowledge to judge one way or the other."  (The letter is dated Sept. 25,
+1861:  "More Letters", I. page 197.)
+
+Bates read his paper before the Linnean Society, Nov. 21, 1861, and
+Darwin's impressions on hearing it were conveyed in a letter to the author
+dated Dec. 3:  "Under a general point of view, I am quite convinced (Hooker
+and Huxley took the same view some months ago) that a philosophic view of
+nature can solely be driven into naturalists by treating special subjects
+as you have done.  Under a special point of view, I think you have solved
+one of the most perplexing problems which could be given to solve."  ("Life
+and Letters", II. page 378.)  The memoir appeared in the following year,
+and after reading it Darwin wrote as follows, Nov. 20, 1862:  "...In my
+opinion it is one of the most remarkable and admirable papers I ever read
+in my life...I am rejoiced that I passed over the whole subject in the
+"Origin", for I should have made a precious mess of it.  You have most
+clearly stated and solved a wonderful problem...Your paper is too good to
+be largely appreciated by the mob of naturalists without souls; but, rely
+on it, that it will have LASTING value, and I cordially congratulate you on
+your first great work.  You will find, I should think, that Wallace will
+fully appreciate it."  ("Life and Letters", II. pages 391-393.)  Four days
+later, Nov. 24, Darwin wrote to Hooker on the same subject:  "I have now
+finished his paper...' it seems to me admirable.  To my mind the act of
+segregation of varieties into species was never so plainly brought forward,
+and there are heaps of capital miscellaneous observations."  ("More
+Letters", I. page 214.)
+
+Darwin was here referring to the tendency of similar varieties of the same
+species to pair together, and on Nov. 25 he wrote to Bates asking for
+fuller information on this subject.  ("More Letters", I. page 215.  See
+also parts of Darwin's letter to Bates in "Life and Letters", II. page
+392.)  If Bates's opinion were well founded, sexual selection would bear a
+most important part in the establishment of such species.  (See Poulton,
+"Essays on Evolution", 1908, pages 65, 85-88.)  It must be admitted,
+however, that the evidence is as yet quite insufficient to establish this
+conclusion.  It is interesting to observe how Darwin at once fixed on the
+part of Bates's memoir which seemed to bear upon sexual selection.  A
+review of Bates's theory of Mimicry was contributed by Darwin to the
+"Natural History Review" (New Ser. Vol. III. 1863, page 219.) and an
+account of it is to be found in the "Origin" (Edition 1872, pages 375-378.)
+and in "The Descent of Man".  (Edition 1874, pages 323-325.)
+
+Darwin continually writes of the value of hypothesis as the inspiration of
+inquiry.  We find an example in his letter to Bates, Nov. 22, 1860:  "I
+have an old belief that a good observer really means a good theorist, and I
+fully expect to find your observations most valuable."  ("More Letters", I.
+page 176.)  Darwin's letter refers to many problems upon which Bates had
+theorised and observed, but as regards Mimicry itself the hypothesis was
+thought out after the return of the letter from the Amazons, when he no
+longer had the opportunity of testing it by the observation of living
+Nature.  It is by no means improbable that, had he been able to apply this
+test, Bates would have recognised that his division of butterfly
+resemblances into two classes,--one due to the theory of mimicry, the other
+to the influence of local conditions,--could not be sustained.
+
+Fritz Muller's contributions to the problem of Mimicry were all made in
+S.E. Brazil, and numbers of them were communicated, with other observations
+on natural history, to Darwin, and by him sent to Professor R. Meldola who
+published many of the facts.  Darwin's letters to Meldola (Poulton,
+"Charles Darwin and the theory of Natural Selection", London, 1896, pages
+199-218.) contain abundant proofs of his interest in Muller's work upon
+Mimicry.  One deeply interesting letter (Loc. cit. pages 201, 202.) dated
+Jan. 23, 1872, proves that Fritz Muller before he originated the theory of
+Common Warning Colours (Synaposematic Resemblance or Mullerian Mimicry),
+which will ever be associated with his name, had conceived the idea of the
+production of mimetic likeness by sexual selection.
+
+Darwin's letter to Meldola shows that he was by no means inclined to
+dismiss the suggestion as worthless, although he considered it daring. 
+"You will also see in this letter a strange speculation, which I should not
+dare to publish, about the appreciation of certain colours being developed
+in those species which frequently behold other forms similarly ornamented. 
+I do not feel at all sure that this view is as incredible as it may at
+first appear.  Similar ideas have passed through my mind when considering
+the dull colours of all the organisms which inhabit dull-coloured regions,
+such as Patagonia and the Galapagos Is."  A little later, on April 5, he
+wrote to Professor August Weismann on the same subject:  "It may be
+suspected that even the habit of viewing differently coloured surrounding
+objects would influence their taste, and Fritz Muller even goes so far as
+to believe that the sight of gaudy butterflies might influence the taste of
+distinct species."  ("Life and Letters", III. page 157.)
+
+This remarkable suggestion affords interesting evidence that F. Muller was
+not satisfied with the sufficiency of Bates's theory.  Nor is this
+surprising when we think of the numbers of abundant conspicuous butterflies
+which he saw exhibiting mimetic likenesses.  The common instances in his
+locality, and indeed everywhere in tropical America, were anything but the
+hard-pressed struggling forms assumed by the theory of Bates.  They
+belonged to the groups which were themselves mimicked by other butterflies.
+Fritz Muller's suggestion also shows that he did not accept Bates's
+alternative explanation of a superficial likeness between models
+themselves, based on some unknown influence of local physico-chemical
+forces.  At the same time Muller's own suggestion was subject to this
+apparently fatal objection, that the sexual selection he invoked would tend
+to produce resemblances in the males rather than the females, while it is
+well known that when the sexes differ the females are almost invariably
+more perfectly mimetic than the males and in a high proportion of cases are
+mimetic while the males are non-mimetic.
+
+The difficulty was met several years later by Fritz Muller's well-known
+theory, published in 1879 ("Kosmos", May 1879, page 100.), and immediately
+translated by Meldola and brought before the Entomological Society. 
+("Proc. Ent. Soc. Lond." 1879, page xx.)  Darwin's letter to Meldola dated
+June 6, 1879, shows "that the first introduction of this new and most
+suggestive hypothesis into this country was due to the direct influence of
+Darwin himself, who brought it before the notice of the one man who was
+likely to appreciate it at its true value and to find the means for its
+presentation to English naturalists."  ("Charles Darwin and the Theory of
+Natural Selection", page 214.)  Of the hypothesis itself Darwin wrote "F.
+Muller's view of the mutual protection was quite new to me."  (Ibid. page
+213.)  The hypothesis of Mullerian mimicry was at first strongly opposed. 
+Bates himself could never make up his mind to accept it.  As the Fellows
+were walking out of the meeting at which Professor Meldola explained the
+hypothesis, an eminent entomologist, now deceased, was heard to say to
+Bates:  "It's a case of save me from my friends!"  The new ideas
+encountered and still encounter to a great extent the difficulty that the
+theory of Bates had so completely penetrated the literature of natural
+history.  The present writer has observed that naturalists who have not
+thoroughly absorbed the older hypothesis are usually far more impressed by
+the newer one than are those whose allegiance has already been rendered. 
+The acceptance of Natural Selection itself was at first hindered by similar
+causes, as Darwin clearly recognised:  "If you argue about the non-
+acceptance of Natural Selection, it seems to me a very striking fact that
+the Newtonian theory of gravitation, which seems to every one now so
+certain and plain, was rejected by a man so extraordinarily able as
+Leibnitz.  The truth will not penetrate a preoccupied mind."  (To Sir J.
+Hooker, July 28, 1868, "More Letters", I. page 305.  See also the letter to
+A.R. Wallace, April 30, 1868, in "More Letters" II. page 77, lines 6-8 from
+top.)
+
+There are many naturalists, especially students of insects, who appear to
+entertain an inveterate hostility to any theory of mimicry.  Some of them
+are eager investigators in the fascinating field of geographical
+distribution, so essential for the study of Mimicry itself.  The changes of
+pattern undergone by a species of Erebia as we follow it over different
+parts of the mountain ranges of Europe is indeed a most interesting
+inquiry, but not more so than the differences between e.g. the Acraea
+johnstoni of S.E. Rhodesia and of Kilimanjaro.  A naturalist who is
+interested by the Erebia should be equally interested by the Acraea; and so
+he would be if the student of mimicry did not also record that the
+characteristics which distinguish the northern from the southern
+individuals of the African species correspond with the presence, in the
+north but not in the south, of certain entirely different butterflies. 
+That this additional information should so greatly weaken, in certain
+minds, the appeal of a favourite study, is a psychological problem of no
+little interest.  This curious antagonism is I believe confined to a few
+students of insects.  Those naturalists who, standing rather farther off,
+are able to see the bearings of the subject more clearly, will usually
+admit the general support yielded by an ever-growing mass of observations
+to the theories of Mimicry propounded by H.W. Bates and Fritz Muller.  In
+like manner natural selection itself was in the early days often best
+understood and most readily accepted by those who were not naturalists. 
+Thus Darwin wrote to D.T. Ansted, Oct. 27, 1860:  "I am often in despair in
+making the generality of NATURALISTS even comprehend me.  Intelligent men
+who are not naturalists and have not a bigoted idea of the term species,
+show more clearness of mind."  ("More Letters", I. page 175.)
+
+Even before the "Origin" appeared Darwin anticipated the first results upon
+the mind of naturalists.  He wrote to Asa Gray, Dec. 21, 1859:  "I have
+made up my mind to be well abused; but I think it of importance that my
+notions should be read by intelligent men, accustomed to scientific
+argument, though NOT naturalists.  It may seem absurd, but I think such men
+will drag after them those naturalists who have too firmly fixed in their
+heads that a species is an entity."  ("Life and Letters" II. page 245.)
+
+Mimicry was not only one of the first great departments of zoological
+knowledge to be studied under the inspiration of natural Selection, it is
+still and will always remain one of the most interesting and important of
+subjects in relation to this theory as well as to evolution.  In mimicry we
+investigate the effect of environment in its simplest form:  we trace the
+effects of the pattern of a single species upon that of another far removed
+from it in the scale of classification.  When there is reason to believe
+that the model is an invader from another region and has only recently
+become an element in the environment of the species native to its second
+home, the problem gains a special interest and fascination.  Although we
+are chiefly dealing with the fleeting and changeable element of colour we
+expect to find and we do find evidence of a comparatively rapid evolution. 
+The invasion of a fresh model is for certain species an unusually sudden
+change in the forces of the environment and in some instances we have
+grounds for the belief that the mimetic response has not been long delayed.
+
+MIMICRY AND SEX.
+
+Ever since Wallace's classical memoir on mimicry in the Malayan Swallowtail
+butterflies, those naturalists who have written on the subject have
+followed his interpretation of the marked prevalence of mimetic resemblance
+in the female sex as compared with the male.  They have believed with
+Wallace that the greater dangers of the female, with slower flight and
+often alighting for oviposition, have been in part met by the high
+development of this special mode of protection.  The fact cannot be
+doubted.  It is extremely common for a non-mimetic male to be accompanied
+by a beautifully mimetic female and often by two or three different forms
+of female, each mimicking a different model.  The male of a polymorphic
+mimetic female is, in fact, usually non-mimetic (e.g. Papilio dardanus =
+merope), or if a mimic (e.g. the Nymphaline genus Euripus), resembles a
+very different model.  On the other hand a non-mimetic female accompanied
+by a mimetic male is excessively rare.  An example is afforded by the
+Oriental Nymphaline, Cethosia, in which the males of some species are rough
+mimics of the brown Danaines.  In some of the orb-weaving spiders the males
+mimic ants, while the much larger females are non-mimetic.  When both sexes
+mimic, it is very common in butterflies and is also known in moths, for the
+females to be better and often far better mimics than the males.
+
+Although still believing that Wallace's hypothesis in large part accounts
+for the facts briefly summarised above, the present writer has recently
+been led to doubt whether it offers a complete explanation.  Mimicry in the
+male, even though less beneficial to the species than mimicry in the
+female, would still surely be advantageous.  Why then is it so often
+entirely restricted to the female?  While the attempt to find an answer to
+this question was haunting me, I re-read a letter written by Darwin to
+Wallace, April 15, 1868, containing the following sentences:  "When female
+butterflies are more brilliant than their males you believe that they have
+in most cases, or in all cases, been rendered brilliant so as to mimic some
+other species, and thus escape danger.  But can you account for the males
+not having been rendered equally brilliant and equally protected?  Although
+it may be most for the welfare of the species that the female should be
+protected, yet it would be some advantage, certainly no disadvantage, for
+the unfortunate male to enjoy an equal immunity from danger.  For my part,
+I should say that the female alone had happened to vary in the right
+manner, and that the beneficial variations had been transmitted to the same
+sex alone.  Believing in this, I can see no improbability (but from analogy
+of domestic animals a strong probability) that variations leading to beauty
+must often have occurred in the males alone, and been transmitted to that
+sex alone.  Thus I should account in many cases for the greater beauty of
+the male over the female, without the need of the protective principle." 
+("More Letters", II. pages 73, 74.  On the same subject--"the gay-coloured
+females of Pieris" (Perrhybris (Mylothris) pyrrha of Brazil), Darwin wrote
+to Wallace, May 5, 1868, as follows:  "I believe I quite follow you in
+believing that the colours are wholly due to mimicry; and I further believe
+that the male is not brilliant from not having received through inheritance
+colour from the female, and from not himself having varied; in short, that
+he has not been influenced by selection."  It should be noted that the male
+of this species does exhibit a mimetic pattern on the under surface.  "More
+Letters" II. page 78.)
+
+The consideration of the facts of mimicry thus led Darwin to the conclusion
+that the female happens to vary in the right manner more commonly than the
+male, while the secondary sexual characters of males supported the
+conviction "that from some unknown cause such characters (viz. new
+characters arising in one sex and transmitted to it alone) apparently
+appear oftener in the male than in the female."  (Letter from Darwin to
+Wallace, May 5, 1867, "More Letters", II. Page 61.)
+
+Comparing these conflicting arguments we are led to believe that the first
+is the stronger.  Mimicry in the male would be no disadvantage but an
+advantage, and when it appears would be and is taken advantage of by
+selection.  The secondary sexual characters of males would be no advantage
+but a disadvantage to females, and, as Wallace thinks, are withheld from
+this sex by selection.  It is indeed possible that mimicry has been
+hindered and often prevented from passing to the males by sexual selection.
+We know that Darwin was much impressed ("Descent of Man", page 325.) by
+Thomas Belt's daring and brilliant suggestion that the white patches which
+exist, although ordinarily concealed, on the wings of mimetic males of
+certain Pierinae (Dismorphia), have been preserved by preferential mating.
+He supposed this result to have been brought about by the females
+exhibiting a deep-seated preference for males that displayed the chief
+ancestral colour, inherited from periods before any mimetic pattern had
+been evolved in the species.  But it has always appeared to me that Belt's
+deeply interesting suggestion requires much solid evidence and repeated
+confirmation before it can be accepted as a valid interpretation of the
+facts.  In the present state of our knowledge, at any rate of insects and
+especially of Lepidoptera, it is probable that the female is more apt to
+vary than the male and that an important element in the interpretation of
+prevalent female mimicry is provided by this fact.
+
+In order adequately to discuss the question of mimicry and sex it would be
+necessary to analyse the whole of the facts, so far as they are known in
+butterflies.  On the present occasion it is only possible to state the
+inferences which have been drawn from general impressions,--inferences
+which it is believed will be sustained by future inquiry.
+
+(1)  Mimicry may occasionally arise in one sex because the differences
+which distinguish it from the other sex happen to be such as to afford a
+starting-point for the resemblance.  Here the male is at no disadvantage as
+compared with the female, and the rarity of mimicry in the male alone (e.g.
+Cethosia) is evidence that the great predominance of female mimicry is not
+to be thus explained.
+
+(2)  The tendency of the female to dimorphism and polymorphism has been of
+great importance in determining this predominance.  Thus if the female
+appear in two different forms and the male in only one it will be twice as
+probable that she will happen to possess a sufficient foundation for the
+evolution of mimicry.
+
+(3)  The appearance of melanic or partially melanic forms in the female has
+been of very great service, providing as it does a change of ground-colour.
+Thus the mimicry of the black generally red-marked American "Aristolochia
+swallowtails" (Pharmacophagus) by the females of Papilio swallowtails was
+probably begun in this way.
+
+(4)  It is probably incorrect to assume with Haase that mimicry always
+arose in the female and was later acquired by the male.  Both sexes of the
+third section of swallowtails (Cosmodesmus) mimic Pharmacophagus in
+America, far more perfectly than do the females of Papilio.  But this is
+not due to Cosmodesmus presenting us with a later stage of history begun in
+Papilio; for in Africa Cosmodesmus is still mimetic (of Danainae) in both
+sexes although the resemblances attained are imperfect, while many African
+species of Papilio have non-mimetic males with beautifully mimetic females.
+The explanation is probably to be sought in the fact that the females of
+Papilio are more variable and more often tend to become dimorphic than
+those of Cosmodesmus, while the latter group has more often happened to
+possess a sufficient foundation for the origin of the resemblance in
+patterns which, from the start, were common to male and female.
+
+(5)  In very variable species with sexes alike, mimicry can be rapidly
+evolved in both sexes out of very small beginnings.  Thus the reddish marks
+which are common in many individuals of Limenitis arthemis were almost
+certainly the starting-point for the evolution of the beautifully mimetic
+L. archippus.  Nevertheless in such cases, although there is no reason to
+suspect any greater variability, the female is commonly a somewhat better
+mimic than the male and often a very much better mimic.  Wallace's
+principle seems here to supply the obvious interpretation.
+
+(6)  When the difference between the patterns of the model and presumed
+ancestor of the mimic is very great, the female is often alone mimetic;
+when the difference is comparatively small, both sexes are commonly
+mimetic.  The Nymphaline genus Hypolimnas is a good example.  In Hypolimnas
+itself the females mimic Danainae with patterns very different from those
+preserved by the non-mimetic males:  in the sub-genus Euralia, both sexes
+resemble the black and white Ethiopian Danaines with patterns not very
+dissimilar from that which we infer to have existed in the non-mimetic
+ancestor.
+
+(7)  Although a melanic form or other large variation may be of the utmost
+importance in facilitating the start of a mimetic likeness, it is
+impossible to explain the evolution of any detailed resemblance in this
+manner.  And even the large colour variation itself may well be the
+expression of a minute and "continuous" change in the chemical and physical
+constitution of pigments.
+
+SEXUAL SELECTION (EPIGAMIC CHARACTERS).
+
+We do not know the date at which the idea of Sexual Selection arose in
+Darwin's mind, but it was probably not many years after the sudden flash of
+insight which, in October 1838, gave to him the theory of Natural
+Selection.  An excellent account of Sexual Selection occupies the
+concluding paragraph of Part I. of Darwin's Section of the Joint Essay on
+Natural Selection, read July 1st, 1858, before the Linnean Society. 
+("Journ. Proc. Linn. Soc." Vol. III. 1859, page 50.)  The principles are so
+clearly and sufficiently stated in these brief sentences that it is
+appropriate to quote the whole:  "Besides this natural means of selection,
+by which those individuals are preserved, whether in their egg, or larval,
+or mature state, which are best adapted to the place they fill in nature,
+there is a second agency at work in most unisexual animals, tending to
+produce the same effect, namely, the struggle of the males for the females. 
+These struggles are generally decided by the law of battle, but in the case
+of birds, apparently, by the charms of their song, by their beauty or their
+power of courtship, as in the dancing rock-thrush of Guiana.  The most
+vigorous and healthy males, implying perfect adaptation, must generally
+gain the victory in their contests.  This kind of selection, however, is
+less rigorous than the other; it does not require the death of the less
+successful, but gives to them fewer descendants.  The struggle falls,
+moreover, at a time of year when food is generally abundant, and perhaps
+the effect chiefly produced would be the modification of the secondary
+sexual characters, which are not related to the power of obtaining food, or
+to defence from enemies, but to fighting with or rivalling other males. 
+The result of this struggle amongst the males may be compared in some
+respects to that produced by those agriculturists who pay less attention to
+the careful selection of all their young animals, and more to the
+occasional use of a choice mate."
+
+A full exposition of Sexual Selection appeared in the "The Descent of Man"
+in 1871, and in the greatly augmented second edition, in 1874.  It has been
+remarked that the two subjects, "The Descent of Man and Selection in
+Relation to Sex", seem to fuse somewhat imperfectly into the single work of
+which they form the title.  The reason for their association is clearly
+shown in a letter to Wallace, dated May 28, 1864:  "...I suspect that a
+sort of sexual selection has been the most powerful means of changing the
+races of man."  ("More Letters", II. page 33.)
+
+Darwin, as we know from his Autobiography ("Life and Letters", I. page
+94.), was always greatly interested in this hypothesis, and it has been
+shown in the preceding pages that he was inclined to look favourably upon
+it as an interpretation of many appearances usually explained by Natural
+Selection.  Hence Sexual Selection, incidentally discussed in other
+sections of the present essay, need not be considered at any length, in the
+section specially allotted to it.
+
+Although so interested in the subject and notwithstanding his conviction
+that the hypothesis was sound, Darwin was quite aware that it was probably
+the most vulnerable part of the "Origin".  Thus he wrote to H.W. Bates,
+April 4, 1861:  "If I had to cut up myself in a review I would have
+(worried?) and quizzed sexual selection; therefore, though I am fully
+convinced that it is largely true, you may imagine how pleased I am at what
+you say on your belief."  ("More Letters", I. page 183.)
+
+The existence of sound-producing organs in the males of insects was, Darwin
+considered, the strongest evidence in favour of the operation of sexual
+selection in this group.  ("Life and Letters", III. pages 94, 138.)  Such a
+conclusion has received strong support in recent years by the numerous
+careful observations of Dr F.A. Dixey ("Proc. Ent. Soc. Lond." 1904, page
+lvi; 1905, pages xxxvii, liv; 1906, page ii.) and Dr G.B. Longstaff ("Proc.
+Ent. Soc. Lond." 1905, page xxxv; "Trans. Ent. Soc. Lond." 1905, page 136;
+1908, page 607.) on the scents of male butterflies.  The experience of
+these naturalists abundantly confirms and extends the account given by
+Fritz Muller ("Jen. Zeit." Vol. XI. 1877, page 99; "Trans. Ent. Soc. Lond."
+1878, page 211.) of the scents of certain Brazilian butterflies.  It is a
+remarkable fact that the apparently epigamic scents of male butterflies
+should be pleasing to man while the apparently aposematic scents in both
+sexes of species with warning colours should be displeasing to him.  But
+the former is far more surprising than the latter.  It is not perhaps
+astonishing that a scent which is ex hypothesi unpleasant to an insect-
+eating Vertebrate should be displeasing to the human sense; but it is
+certainly wonderful that an odour which is ex hypothesi agreeable to a
+female butterfly should also be agreeable to man.
+
+Entirely new light upon the seasonal appearance of epigamic characters is
+shed by the recent researches of C.W. Beebe ("The American Naturalist",
+Vol. XLII. No. 493, Jan. 1908, page 34.), who caused the scarlet tanager
+(Piranga erythromelas) and the bobolink (Dolichonyx oryzivorus) to retain
+their breeding plumage through the whole year by means of fattening food,
+dim illumination, and reduced activity.  Gradual restoration to the light
+and the addition of meal-worms to the diet invariably brought back the
+spring song, even in the middle of winter.  A sudden alteration of
+temperature, either higher or lower, caused the birds nearly to stop
+feeding, and one tanager lost weight rapidly and in two weeks moulted into
+the olive-green winter plumage.  After a year, and at the beginning of the
+normal breeding season, "individual tanagers and bobolinks were gradually
+brought under normal conditions and activities," and in every case moulted
+from nuptial plumage to nuptial plumage.  "The dull colours of the winter
+season had been skipped."  The author justly claims to have established
+"that the sequence of plumage in these birds is not in any way predestined
+through inheritance..., but that it may be interrupted by certain factors
+in the environmental complex."
+
+
+XVI.  GEOGRAPHICAL DISTRIBUTION OF PLANTS.
+
+By SIR WILLIAM THISELTON-DYER, K.C.M.G., C.I.E. Sc.D., F.R.S.
+
+The publication of "The Origin of Species" placed the study of Botanical
+Geography on an entirely new basis.  It is only necessary to study the
+monumental "Geographie Botanique raisonnee" of Alphonse De Candolle,
+published four years earlier (1855), to realise how profound and far-
+reaching was the change.  After a masterly and exhaustive discussion of all
+available data De Candolle in his final conclusions could only arrive at a
+deadlock.  It is sufficient to quote a few sentences:--
+
+"L'opinion de Lamarck est aujourd'hui abandonee par tous les naturalistes
+qui ont etudie sagement les modifications possibles des etres organises...
+
+"Et si l'on s'ecarte des exagerations de Lamarck, si l'on suppose un
+premier type de chaque genre, de chaque famille tout au moins, on se trouve
+encore a l'egard de l'origine de ces types en presence de la grande
+question de la creation.
+
+"Le seul parti a prendre est donc d'envisager les etres organises comme
+existant depuis certaines epoques, avec leurs qualites particulieres." 
+(Vol. II. page 1107.)
+
+Reviewing the position fourteen years afterwards, Bentham remarked:--"These
+views, generally received by the great majority of naturalists at the time
+De Candolle wrote, and still maintained by a few, must, if adhered to,
+check all further enquiry into any connection of facts with causes," and he
+added, "there is little doubt but that if De Candolle were to revise his
+work, he would follow the example of so many other eminent naturalists,
+and...insist that the present geographical distribution of plants was in
+most instances a derivative one, altered from a very different former
+distribution."  ("Pres. Addr." (1869) "Proc. Linn. Soc." 1868-69, page
+lxviii.)
+
+Writing to Asa Gray in 1856, Darwin gave a brief preliminary account of his
+ideas as to the origin of species, and said that geographical distribution
+must be one of the tests of their validity.  ("Life and Letters", II. page
+78.)  What is of supreme interest is that it was also their starting-point. 
+He tells us:--"When I visited, during the voyage of H.M.S. "Beagle", the
+Galapagos Archipelago,...I fancied myself brought near to the very act of
+creation.  I often asked myself how these many peculiar animals and plants
+had been produced:  the simplest answer seemed to be that the inhabitants
+of the several islands had descended from each other, undergoing
+modification in the course of their descent."  ("The Variation of Animals
+and Plants" (2nd edition), 1890, I. pages 9, 10.)  We need not be surprised
+then, that in writing in 1845 to Sir Joseph Hooker, he speaks of "that
+grand subject, that almost keystone of the laws of creation, Geographical
+Distribution."  ("Life and Letters", I. page 336.)
+
+Yet De Candolle was, as Bentham saw, unconsciously feeling his way, like
+Lyell, towards evolution, without being able to grasp it.  They both strove
+to explain phenomena by means of agencies which they saw actually at work. 
+If De Candolle gave up the ultimate problem as insoluble:--"La creation ou
+premiere formation des etres organises echappe, par sa nature et par son
+anciennete, a nos moyens d'observation" (Loc. cit. page 1106.), he steadily
+endeavoured to minimise its scope.  At least half of his great work is
+devoted to the researches by which he extricated himself from a belief in
+species having had a multiple origin, the view which had been held by
+successive naturalists from Gmelin to Agassiz.  To account for the obvious
+fact that species constantly occupy dissevered areas, De Candolle made a
+minute study of their means of transport.  This was found to dispose of the
+vast majority of cases, and the remainder he accounted for by geographical
+change.  (Loc. cit. page 1116.)
+
+But Darwin strenuously objected to invoking geographical change as a
+solution of every difficulty.  He had apparently long satisfied himself as
+to the "permanence of continents and great oceans."  Dana, he tells us
+"was, I believe, the first man who maintained" this ("Life and Letters",
+III. page 247.  Dana says:--"The continents and oceans had their general
+outline or form defined in earliest time," "Manual of Geology", revised
+edition.  Philadelphia, 1869, page 732.  I have no access to an earlier
+edition.), but he had himself probably arrived at it independently.  Modern
+physical research tends to confirm it.  The earth's centre of gravity, as
+pointed out by Pratt from the existence of the Pacific Ocean, does not
+coincide with its centre of figure, and it has been conjectured that the
+Pacific Ocean dates its origin from the separation of the moon from the
+earth.
+
+The conjecture appears to be unnecessary.  Love shows that "the force that
+keeps the Pacific Ocean on one side of the earth is gravity, directed more
+towards the centre of gravity than the centre of the figure."  ("Report of
+the 77th Meeting of the British Association" (Leicester, 1907), London,
+1908, page 431.)  I can only summarise the conclusions of a technical but
+masterly discussion.  "The broad general features of the distribution of
+continent and ocean can be regarded as the consequences of simple causes of
+a dynamical character," and finally, "As regards the contour of the great
+ocean basins, we seem to be justified in saying that the earth is
+approximately an oblate spheroid, but more nearly an ellipsoid with three
+unequal axes, having its surface furrowed according to the formula for a
+certain spherical harmonic of the third degree" (Ibid. page 436.), and he
+shows that this furrowed surface must be produced "if the density is
+greater in one hemispheroid than in the other, so that the position of the
+centre of gravity is eccentric."  (Ibid. page 431.)  Such a modelling of
+the earth's surface can only be referred to a primitive period of
+plasticity.  If the furrows account for the great ocean basins, the
+disposition of the continents seems equally to follow.  Sir George Darwin
+has pointed out that they necessarily "arise from a supposed primitive
+viscosity or plasticity of the earth's mass.  For during this course of
+evolution the earth's mass must have suffered a screwing motion, so that
+the polar regions have travelled a little from west to east relatively to
+the equator.  This affords a possible explanation of the north and south
+trend of our great continents."  ("Encycl. Brit." (9th edition), Vol.
+XXIII. "Tides", page 379.)
+
+It would be trespassing on the province of the geologist to pursue the
+subject at any length.  But as Wallace ("Island Life" (2nd edition), 1895,
+page 103.), who has admirably vindicated Darwin's position, points out, the
+"question of the permanence of our continents...lies at the root of all our
+inquiries into the great changes of the earth and its inhabitants."  But he
+proceeds:  "The very same evidence which has been adduced to prove the
+GENERAL stability and permanence of our continental areas also goes to
+prove that they have been subjected to wonderful and repeated changes in
+DETAIL."  (Loc. cit. page 101.)  Darwin of course would have admitted this,
+for with a happy expression he insisted to Lyell (1856) that "the
+skeletons, at least, of our continents are ancient."  ("More Letters", II.
+page 135.)  It is impossible not to admire the courage and tenacity with
+which he carried on the conflict single-handed.  But he failed to convince
+Lyell.  For we still find him maintaining in the last edition of the
+"Principles":  "Continents therefore, although permanent for whole
+geological epochs, shift their positions entirely in the course of ages." 
+(Lyell's "Principles of Geology" (11th edition), London, 1872, I. page
+258.)
+
+Evidence, however, steadily accumulates in Darwin's support.  His position
+still remains inexpugnable that it is not permissible to invoke
+geographical change to explain difficulties in distribution without valid
+geological and physical support.  Writing to Mellard Reade, who in 1878 had
+said, "While believing that the ocean-depths are of enormous age, it is
+impossible to reject other evidences that they have once been land," he
+pointed out "the statement from the 'Challenger' that all sediment is
+deposited within one or two hundred miles from the shores."  ("More
+Letters", II. page 146.)  The following year Sir Archibald Geikie
+("Geographical Evolution", "Proc. R. Geogr. Soc." 1879, page 427.) informed
+the Royal Geographical Society that "No part of the results obtained by the
+'Challenger' expedition has a profounder interest for geologists and
+geographers than the proof which they furnish that the floor of the ocean
+basins has no real analogy among the sedimentary formations which form most
+of the framework of the land."
+
+Nor has Darwin's earlier argument ever been upset.  "The fact which I
+pointed out many years ago, that all oceanic islands are volcanic (except
+St Paul's, and now that is viewed by some as the nucleus of an ancient
+volcano), seem to me a strong argument that no continent ever occupied the
+great oceans."  ("More Letters", II. page 146.)
+
+Dr Guppy, who devoted several years to geological and botanical
+investigations in the Pacific, found himself forced to similar conclusions.
+"It may be at once observed," he says, "that my belief in the general
+principle that islands have always been islands has not been shaken," and
+he entirely rejects "the hypothesis of a Pacific continent."  He comes
+back, in full view of the problems on the spot, to the position from which,
+as has been seen, Darwin started:  "If the distribution of a particular
+group of plants or animals does not seem to accord with the present
+arrangement of the land, it is by far the safest plan, even after
+exhausting all likely modes of explanation, not to invoke the intervention
+of geographical changes; and I scarcely think that our knowledge of any one
+group of organisms is ever sufficiently precise to justify a recourse to
+hypothetical alterations in the present relations of land and sea." 
+("Observations of a Naturalist in the Pacific between 1896 and 1899",
+London, 1903, I. page 380.)  Wallace clinches the matter when he finds
+"almost the whole of the vast areas of the Atlantic, Pacific, Indian, and
+Southern Oceans, without a solitary relic of the great islands or
+continents supposed to have sunk beneath their waves."  ("Island Life",
+page 105.)
+
+Writing to Wallace (1876), Darwin warmly approves the former's "protest
+against sinking imaginary continents in a quite reckless manner, as was
+stated by Forbes, followed, alas, by Hooker, and caricatured by Wollaston
+and (Andrew) Murray."  ("Life and Letters", III. page 230.)  The transport
+question thus became of enormously enhanced importance.  We need not be
+surprised then at his writing to Lyell in 1856:--"I cannot avoid thinking
+that Forbes's 'Atlantis' was an ill-service to science, as checking a close
+study of means of dissemination" (Ibid. II. page 78.), and Darwin spared no
+pains to extend our knowledge of them.  He implores Hooker, ten years
+later, to "admit how little is known on the subject," and summarises with
+some satisfaction what he had himself achieved:--"Remember how recently you
+and others thought that salt water would soon kill seeds...Remember that no
+one knew that seeds would remain for many hours in the crops of birds and
+retain their vitality; that fish eat seeds, and that when the fish are
+devoured by birds the seeds can germinate, etc.  Remember that every year
+many birds are blown to Madeira and to the Bermudas.  Remember that dust is
+blown 1000 miles across the Atlantic."  ("More Letters", I. page 483.)
+
+It has always been the fashion to minimise Darwin's conclusions, and these
+have not escaped objection.  The advocatus diaboli has a useful function in
+science.  But in attacking Darwin his brief is generally found to be
+founded on a slender basis of facts.  Thus Winge and Knud Andersen have
+examined many thousands of migratory birds and found "that their crops and
+stomachs were always empty.  They never observed any seeds adhering to the
+feathers, beaks or feet of the birds."  (R.F. Scharff, "European Animals",
+page 64, London, 1907.)  The most considerable investigation of the problem
+of Plant Dispersal since Darwin is that of Guppy.  He gives a striking
+illustration of how easily an observer may be led into error by relying on
+negative evidence.
+
+"When Ekstam published, in 1895, the results of his observations on the
+plants of Nova Zembla, he observed that he possessed no data to show
+whether swimming and wading birds fed on berries; and he attached all
+importance to dispersal by winds.  On subsequently visiting Spitzbergen he
+must have been at first inclined, therefore, to the opinion of Nathorst,
+who, having found only a solitary species of bird (a snow-sparrow) in that
+region, naturally concluded that birds had been of no importance as agents
+in the plant-stocking.  However, Ekstam's opportunities were greater, and
+he tells us that in the craws of six specimens of Lagopus hyperboreus shot
+in Spitzbergen in August he found represented almost 25 per cent. of the
+usual phanerogamic flora of that region in the form of fruits, seeds,
+bulbils, flower-buds, leaf-buds, etc..."
+
+"The result of Ekstam's observations in Spitzbergen was to lead him to
+attach a very considerable importance in plant dispersal to the agency of
+birds; and when in explanation of the Scandinavian elements in the
+Spitzbergen flora he had to choose between a former land connection and the
+agency of birds, he preferred the bird."  (Guppy, op. cit. II. pages 511,
+512.)
+
+Darwin objected to "continental extensions" on geological grounds, but he
+also objected to Lyell that they do not "account for all the phenomena of
+distribution on islands" ("Life and Letters", II. page 77.), such for
+example as the absence of Acacias and Banksias in New Zealand.  He agreed
+with De Candolle that "it is poor work putting together the merely POSSIBLE
+means of distribution."  But he also agreed with him that they were the
+only practicable door of escape from multiple origins.  If they would not
+work then "every one who believes in single centres will have to admit
+continental extensions" (Ibid. II. page 82.), and that he regarded as a
+mere counsel of despair:--"to make continents, as easily as a cook does
+pancakes."  (Ibid. II. page 74.)
+
+The question of multiple origins however presented itself in another shape
+where the solution was much more difficult.  The problem, as stated by
+Darwin, is this:--"The identity of many plants and animals, on mountain-
+summits, separated from each other by hundreds of miles of
+lowlands...without the apparent possibility of their having migrated from
+one point to the other."  He continues, "even as long ago as 1747, such
+facts led Gmelin to conclude that the same species must have been
+independently created at several distinct points; and we might have
+remained in this same belief, had not Agassiz and others called vivid
+attention to the Glacial period, which affords...a simple explanation of
+the facts."  ("Origin of Species" (6th edition) page 330.)
+
+The "simple explanation" was substantially given by E. Forbes in 1846.  It
+is scarcely too much to say that it belongs to the same class of fertile
+and far-reaching ideas as "natural selection" itself.  It is an
+extraordinary instance, if one were wanted at all, of Darwin's magnanimity
+and intense modesty that though he had arrived at the theory himself, he
+acquiesced in Forbes receiving the well-merited credit.  "I have never," he
+says, "of course alluded in print to my having independently worked out
+this view."  But he would have been more than human if he had not added:--
+"I was forestalled in...one important point, which my vanity has always
+made me regret."  ("Life and Letters", I. page 88.)
+
+Darwin, however, by applying the theory to trans-tropical migration, went
+far beyond Forbes.  The first enunciation to this is apparently contained
+in a letter to Asa Gray in 1858.  The whole is too long to quote, but the
+pith is contained in one paragraph.  "There is a considerable body of
+geological evidence that during the Glacial epoch the whole world was
+colder; I inferred that,...from erratic boulder phenomena carefully
+observed by me on both the east and west coast of South America.  Now I am
+so bold as to believe that at the height of the Glacial epoch, AND WHEN ALL
+TROPICAL PRODUCTIONS MUST HAVE BEEN CONSIDERABLY DISTRESSED, several
+temperate forms slowly travelled into the heart of the Tropics, and even
+reached the southern hemisphere; and some few southern forms penetrated in
+a reverse direction northward."  ("Life and Letters", II. page 136.)  Here
+again it is clear that though he credits Agassiz with having called vivid
+attention to the Glacial period, he had himself much earlier grasped the
+idea of periods of refrigeration.
+
+Putting aside the fact, which has only been made known to us since Darwin's
+death, that he had anticipated Forbes, it is clear that he gave the theory
+a generality of which the latter had no conception.  This is pointed out by
+Hooker in his classical paper "On the Distribution of Arctic Plants"
+(1860).  "The theory of a southern migration of northern types being due to
+the cold epochs preceding and during the glacial, originated, I believe,
+with the late Edward Forbes; the extended one, of the trans-tropical
+migration, is Mr Darwin's."  ("Linn. Trans." XXIII. page 253.  The attempt
+appears to have been made to claim for Heer priority in what I may term for
+short the arctic-alpine theory (Scharff, "European Animals", page 128).  I
+find no suggestion of his having hit upon it in his correspondence with
+Darwin or Hooker.  Nor am I aware of any reference to his having done so in
+his later publications.  I am indebted to his biographer, Professor
+Schroter, of Zurich, for an examination of his earlier papers with an
+equally negative result.)  Assuming that local races have derived from a
+common ancestor, Hooker's great paper placed the fact of the migration on
+an impregnable basis.  And, as he pointed out, Darwin has shown that "such
+an explanation meets the difficulty of accounting for the restriction of so
+many American and Asiatic arctic types to their own peculiar longitudinal
+zones, and for what is a far greater difficulty, the representation of the
+same arctic genera by most closely allied species in different longitudes."
+
+The facts of botanical geography were vital to Darwin's argument.  He had
+to show that they admitted of explanation without assuming multiple origins
+for species, which would be fatal to the theory of Descent.  He had
+therefore to strengthen and extend De Candolle's work as to means of
+transport.  He refused to supplement them by hypothetical geographical
+changes for which there was no independent evidence:  this was simply to
+attempt to explain ignotum per ignotius.  He found a real and, as it has
+turned out, a far-reaching solution in climatic change due to cosmical
+causes which compelled the migration of species as a condition of their
+existence.  The logical force of the argument consists in dispensing with
+any violent assumption, and in showing that the principle of descent is
+adequate to explain the ascertained facts.
+
+It does not, I think, detract from the merit of Darwin's conclusions that
+the tendency of modern research has been to show that the effects of the
+Glacial period were less simple, more localised and less general than he
+perhaps supposed.  He admitted that "equatorial refrigeration...must have
+been small."  ("More Letters", I. page 177.)  It may prove possible to
+dispense with it altogether.  One cannot but regret that as he wrote to
+Bates:--"the sketch in the 'Origin' gives a very meagre account of my
+fuller MS. essay on this subject."  (Loc. cit.)  Wallace fully accepted
+"the effect of the Glacial epoch in bringing about the present distribution
+of Alpine and Arctic plants in the NORTHERN HEMISPHERE," but rejected "the
+lowering of the temperature of the tropical regions during the Glacial
+period" in order to account for their presence in the SOUTHERN hemisphere. 
+("More Letters", II. page 25 (footnote 1).)  The divergence however does
+not lie very deep.  Wallace attaches more importance to ordinary means of
+transport.  "If plants can pass in considerable numbers and variety over
+wide seas and oceans, it must be yet more easy for them to traverse
+continuous areas of land, wherever mountain-chains offer suitable
+stations."  ("Island Life" (2nd edition), London, 1895, page 512.)  And he
+argues that such periodical changes of climate, of which the Glacial period
+may be taken as a type, would facilitate if not stimulate the process. 
+(Loc. cit. page 518.)
+
+It is interesting to remark that Darwin drew from the facts of plant
+distribution one of his most ingenious arguments in support of this theory. 
+(See "More Letters", I. page 424.)  He tells us, "I was led to anticipate
+that the species of the larger genera in each country would oftener present
+varieties, than the species of the smaller genera."  ("Origin", page 44.) 
+He argues "where, if we may use the expression, the manufactory of species
+has been active, we ought generally to find the manufactory still in
+action."  (Ibid. page 45.)  This proved to be the case.  But the labour
+imposed upon him in the study was immense.  He tabulated local floras
+"belting the whole northern hemisphere" ("More Letters", I. page 107.),
+besides voluminous works such as De Candolle's "Prodromus".  The results
+scarcely fill a couple of pages.  This is a good illustration of the
+enormous pains which he took to base any statement on a secure foundation
+of evidence, and for this the world, till the publication of his letters,
+could not do him justice.  He was a great admirer of Herbert Spencer, whose
+"prodigality of original thought" astonished him.  "But," he says, "the
+reflection constantly recurred to me that each suggestion, to be of real
+value to service, would require years of work."  (Ibid. II. page 235.)
+
+At last the ground was cleared and we are led to the final conclusion.  "If
+the difficulties be not insuperable in admitting that in the long course of
+time all the individuals of the same species belonging to the same genus,
+have proceeded from some one source; then all the grand leading facts of
+geographical distribution are explicable on the theory of migration,
+together with subsequent modification and the multiplication of new forms."
+("Origin", page 360.)  In this single sentence Darwin has stated a theory
+which, as his son F. Darwin has said with justice, has "revolutionized
+botanical geography."  ("The Botanical Work of Darwin", "Ann. Bot." 1899, 
+page xi.)  It explains how physical barriers separate and form botanical
+regions; how allied species become concentrated in the same areas; how,
+under similar physical conditions, plants may be essentially dissimilar,
+showing that descent and not the surroundings is the controlling factor;
+how insular floras have acquired their peculiarities; in short how the most
+various and apparently uncorrelated problems fall easily and inevitably
+into line.
+
+The argument from plant distribution was in fact irresistible.  A proof, if
+one were wanted, was the immediate conversion of what Hooker called "the
+stern keen intellect" ("More Letters", I. page 134.) of Bentham, by general
+consent the leading botanical systematist at the time.  It is a striking
+historical fact that a paper of his own had been set down for reading at
+the Linnean Society on the same day as Darwin's, but had to give way.  In
+this he advocated the fixity of species.  He withdrew it after hearing
+Darwin's.  We can hardly realise now the momentous effect on the scientific
+thought of the day of the announcement of the new theory.  Years afterwards
+(1882) Bentham, notwithstanding his habitual restraint, could not write of
+it without emotion.  "I was forced, however reluctantly, to give up my
+long-cherished convictions, the results of much labour and study."  The
+revelation came without preparation.  Darwin, he wrote, "never made any
+communications to me in relation to his views and labours."  But, he adds,
+I...fully adopted his theories and conclusions, notwithstanding the severe
+pain and disappointment they at first occasioned me."  ("Life and Letters",
+II. page 294.)  Scientific history can have few incidents more worthy.  I
+do not know what is most striking in the story, the pathos or the moral
+dignity of Bentham's attitude.
+
+Darwin necessarily restricted himself in the "Origin" to establishing the
+general principles which would account for the facts of distribution, as a
+part of his larger argument, without attempting to illustrate them in
+particular cases.  This he appears to have contemplated doing in a separate
+work.  But writing to Hooker in 1868 he said:--"I shall to the day of my
+death keep up my full interest in Geographical Distribution, but I doubt
+whether I shall ever have strength to come in any fuller detail than in the
+"Origin" to this grand subject."  ("More Letters", II. page 7.)  This must
+be always a matter for regret.  But we may gather some indication of his
+later speculations from the letters, the careful publication of which by F.
+Darwin has rendered a service to science, the value of which it is
+difficult to exaggerate.  They admit us to the workshop, where we see a
+great theory, as it were, in the making.  The later ideas that they contain
+were not it is true public property at the time.  But they were
+communicated to the leading biologists of the day and indirectly have had a
+large influence.
+
+If Darwin laid the foundation, the present fabric of Botanical Geography
+must be credited to Hooker.  It was a happy partnership.  The far-seeing,
+generalising power of the one was supplied with data and checked in
+conclusions by the vast detailed knowledge of the other.  It may be
+permitted to quote Darwin's generous acknowledgment when writing the
+"Origin":--"I never did pick any one's pocket, but whilst writing my
+present chapter I keep on feeling (even when differing most from you) just
+as if I were stealing from you, so much do I owe to your writings and
+conversation, so much more than mere acknowledgements show."  ("Life and
+Letters", II. page 148 (footnote).)  Fourteen years before he had written
+to Hooker:  "I know I shall live to see you the first authority in Europe
+on...Geographical Distribution."  (Ibid. I. page 336.)  We owe it to Hooker
+that no one now undertakes the flora of a country without indicating the
+range of the species it contains.  Bentham tells us:  "After De Candolle,
+independently of the great works of Darwin...the first important addition
+to the science of geographical botany was that made by Hooker in his
+"Introductory Essay to the Flora of Tasmania", which, though
+contemporaneous only with the "Origin of Species", was drawn up with a
+general knowledge of his friend's observations and views."  (Pres. Addr.
+(1869), "Proc. Linn. Soc." 1868-69, page lxxiv.)  It cannot be doubted that
+this and the great memoir on the "Distribution of Arctic Plants" were only
+less epoch-making than the "Origin" itself, and must have supplied a
+powerful support to the general theory of organic evolution.
+
+Darwin always asserted his "entire ignorance of Botany."  ("More Letters",
+I. page 400.)  But this was only part of his constant half-humorous self-
+depreciation.  He had been a pupil of Henslow, and it is evident that he
+had a good working knowledge of systematic botany.  He could find his way
+about in the literature and always cites the names of plants with
+scrupulous accuracy.  It was because he felt the want of such a work for
+his own researches that he urged the preparation of the "Index Kewensis",
+and undertook to defray the expense.  It has been thought singular that he
+should have been elected a "correspondant" of the Academie des Sciences in
+the section of Botany, but it is not surprising that his work in
+Geographical Botany made the botanists anxious to claim him.  His heart
+went with them.  "It has always pleased me," he tells us, "to exalt plants
+in the scale of organised beings."  ("Life and Letters", I. page 98.)  And
+he declares that he finds "any proposition more easily tested in botanical
+works (Ibid. II. page 99.) than in zoological."
+
+In the "Introductory Essay" Hooker dwelt on the "continuous current of
+vegetation from Scandinavia to Tasmania" ("Introductory Essay to the Flora
+of Tasmania", London, 1859.  Reprinted from the "Botany of the Antarctic
+Expedition", Part III., "Flora of Tasmania", Vol I. page ciii.), but finds
+little evidence of one in the reverse direction.  "In the New World,
+Arctic, Scandinavian, and North American genera and species are
+continuously extended from the north to the south temperate and even
+Antarctic zones; but scarcely one Antarctic species, or even genus advances
+north beyond the Gulf of Mexico" (page civ.).  Hooker considered that this
+negatived "the idea that the Southern and Northern Floras have had common
+origin within comparatively modern geological epochs."  (Loc. cit.)  This
+is no doubt a correct conclusion.  But it is difficult to explain on
+Darwin's view alone, of alternating cold in the two hemispheres, the
+preponderant migration from the north to the south.  He suggests,
+therefore, that it "is due to the greater extent of land in the north and
+to the northern forms...having...been advanced through natural selection
+and competition to a higher stage of perfection or dominating power." 
+("Origin of Species" (6th edition), page 340; cf. also "Life and Letters",
+II. page 142.)  The present state of the Flora of New Zealand affords a
+striking illustration of the correctness of this view.  It is poor in
+species, numbering only some 1400, of which three-fourths are endemic. 
+They seem however quite unable to resist the invasion of new comers and
+already 600 species of foreign origin have succeeded in establishing
+themselves.
+
+If we accept the general configuration of the earth's surface as permanent
+a continuous and progressive dispersal of species from the centre to the
+circumference, i.e. southwards, seems inevitable.  If an observer were
+placed above a point in St George's Channel from which one half of the
+globe was visible he would see the greatest possible quantity of land
+spread out in a sort of stellate figure.  The maritime supremacy of the
+English race has perhaps flowed from the central position of its home. 
+That such a disposition would facilitate a centrifugal migration of land
+organisms is at any rate obvious, and fluctuating conditions of climate
+operating from the pole would supply an effective means of propulsion.  As
+these became more rigorous animals at any rate would move southwards to
+escape them.  It would be equally the case with plants if no insuperable
+obstacle interposed.  This implies a mobility in plants, notwithstanding
+what we know of means of transport which is at first sight paradoxical. 
+Bentham has stated this in a striking way:  "Fixed and immovable as is the
+individual plant, there is no class in which the race is endowed with
+greater facilities for the widest dispersion...Plants cast away their
+offspring in a dormant state, ready to be carried to any distance by those
+external agencies which we may deem fortuitous, but without which many a
+race might perish from the exhaustion of the limited spot of soil in which
+it is rooted."  (Pres. Addr.(1869), "Proc. Linn. Soc." 1868-69, pages lxvi,
+lxvii.)
+
+I have quoted this passage from Bentham because it emphasises a point which
+Darwin for his purpose did not find it necessary to dwell upon, though he
+no doubt assumed it.  Dispersal to a distance is, so to speak, an
+accidental incident in the life of a species.  Lepidium Draba, a native of
+South-eastern Europe, owes its prevalence in the Isle of Thanet to the
+disastrous Walcheren expedition; the straw-stuffing of the mattresses of
+the fever-stricken soldiers who were landed there was used by a farmer for
+manure.  Sir Joseph Hooker ("Royal Institution Lecture", April 12, 1878.)
+tells us that landing on Lord Auckland's Island, which was uninhabited,
+"the first evidence I met with of its having been previously visited by man
+was the English chickweed; and this I traced to a mound that marked the
+grave of a British sailor, and that was covered with the plant, doubtless
+the offspring of seed that had adhered to the spade or mattock with which
+the grave had been dug."
+
+Some migration from the spot where the individuals of a species have
+germinated is an essential provision against extinction.  Their descendants
+otherwise would be liable to suppression by more vigorous competitors.  But
+they would eventually be extinguished inevitably, as pointed out by
+Bentham, by the exhaustion of at any rate some one necessary constituent of
+the soil.  Gilbert showed by actual analysis that the production of a
+"fairy ring" is simply due to the using up by the fungi of the available
+nitrogen in the enclosed area which continually enlarges as they seek a
+fresh supply on the outside margin.  Anyone who cultivates a garden can
+easily verify the fact that every plant has some adaptation for varying
+degrees of seed-dispersal.  It cannot be doubted that slow but persistent
+terrestrial migration has played an enormous part in bringing about
+existing plant-distribution, or that climatic changes would intensify the
+effect because they would force the abandonment of a former area and the
+occupation of a new one.  We are compelled to admit that as an incident of
+the Glacial period a whole flora may have moved down and up a mountain
+side, while only some of its constituent species would be able to take
+advantage of means of long-distance transport.
+
+I have dwelt on the importance of what I may call short-distance dispersal
+as a necessary condition of plant life, because I think it suggests the
+solution of a difficulty which leads Guppy to a conclusion with which I am
+unable to agree.  But the work which he has done taken as a whole appears
+to me so admirable that I do so with the utmost respect.  He points out, as
+Bentham had already done, that long-distance dispersal is fortuitous.  And
+being so it cannot have been provided for by previous adaptation.  He says
+(Guppy, op. cit. II. page 99.):  "It is not conceivable that an organism
+can be adapted to conditions outside its environment."  To this we must
+agree; but, it may be asked, do the general means of plant dispersal
+violate so obvious a principle?  He proceeds:  "The great variety of the
+modes of dispersal of seeds is in itself an indication that the dispersing
+agencies avail themselves in a hap-hazard fashion of characters and
+capacities that have been developed in other connections."  (Loc. cit. page
+102.)  "Their utility in these respects is an accident in the plant's
+life."  (Loc. cit. page 100.)  He attributes this utility to a "determining
+agency," an influence which constantly reappears in various shapes in the
+literature of Evolution and is ultra-scientific in the sense that it bars
+the way to the search for material causes.  He goes so far as to doubt
+whether fleshy fruits are an adaptation for the dispersal of their
+contained seeds.  (Loc. cit. page 102.)  Writing as I am from a hillside
+which is covered by hawthorn bushes sown by birds, I confess I can feel
+little doubt on the subject myself.  The essential fact which Guppy brings
+out is that long-distance unlike short-distance dispersal is not universal
+and purposeful, but selective and in that sense accidental.  But it is not
+difficult to see how under favouring conditions one must merge into the
+other.
+
+Guppy has raised one novel point which can only be briefly referred to but
+which is of extreme interest.  There are grounds for thinking that flowers
+and insects have mutually reacted upon one another in their evolution. 
+Guppy suggests that something of the same kind may be true of birds.  I
+must content myself with the quotation of a single sentence.  "With the
+secular drying of the globe and the consequent differentiation of climate
+is to be connected the suspension to a great extent of the agency of birds
+as plant dispersers in later ages, not only in the Pacific Islands but all
+over the tropics.  The changes of climate, birds and plants have gone on
+together, the range of the bird being controlled by the climate, and the
+distribution of the plant being largely dependent on the bird."  (Loc.cit.
+II. page 221.)
+
+Darwin was clearly prepared to go further than Hooker in accounting for the
+southern flora by dispersion from the north.  Thus he says:  "We must, I
+suppose, admit that every yard of land has been successively covered with a
+beech-forest between the Caucasus and Japan."  ("More Letters", II. page
+9.)  Hooker accounted for the dissevered condition of the southern flora by
+geographical change, but this Darwin could not admit.  He suggested to
+Hooker that the Australian and Cape floras might have had a point of
+connection through Abyssinia (Ibid. I. page 447.), an idea which was
+promptly snuffed out.  Similarly he remarked to Bentham (1869):  "I suppose
+you think that the Restiaceae, Proteaceae, etc., etc. once extended over
+the whole world, leaving fragments in the south."  (Ibid. I. page 380.) 
+Eventually he conjectured "that there must have been a Tertiary Antarctic
+continent, from which various forms radiated to the southern extremities of
+our present continents."  ("Life and Letters", III. page 231.)  But
+characteristically he could not admit any land connections and trusted to
+"floating ice for transporting seed."  ("More Letters", I. page 116.)  I am
+far from saying that this theory is not deserving of serious attention,
+though there seems to be no positive evidence to support it, and it
+immediately raises the difficulty how did such a continent come to be
+stocked?
+
+We must, however, agree with Hooker that the common origin of the northern
+and southern floras must be referred to a remote past.  That Darwin had
+this in his mind at the time of the publication of the "Origin" is clear
+from a letter to Hooker.  "The view which I should have looked at as
+perhaps most probable (though it hardly differs from yours) is that the
+whole world during the Secondary ages was inhabited by marsupials,
+araucarias (Mem.--Fossil wood of this nature in South America), Banksia,
+etc.; and that these were supplanted and exterminated in the greater area
+of the north, but were left alive in the south."  (Ibid. I. page 453.) 
+Remembering that Araucaria, unlike Banksia, belongs to the earlier Jurassic
+not to the angiospermous flora, this view is a germinal idea of the widest
+generality.
+
+The extraordinary congestion in species of the peninsulas of the Old World
+points to the long-continued action of a migration southwards.  Each is in
+fact a cul-de-sac into which they have poured and from which there is no
+escape.  On the other hand the high degree of specialisation in the
+southern floras and the little power the species possess of holding their
+own in competition or in adaptation to new conditions point to long-
+continued isolation.  "An island...will prevent free immigration and
+competition, hence a greater number of ancient forms will survive."  (Ibid.
+I. page 481.)  But variability is itself subject to variation.  The nemesis
+of a high degree of protected specialisation is the loss of adaptability. 
+(See Lyell, "The Geological Evidences of the Antiquity of Man", London,
+1863, page 446.)  It is probable that many elements of the southern flora
+are doomed:  there is, for example, reason to think that the singular
+Stapelieae of S. Africa are a disappearing group.  The tree Lobelias which
+linger in the mountains of Central Africa, in Tropical America and in the
+Sandwich Islands have the aspect of extreme antiquity.  I may add a further
+striking illustration from Professor Seward:  "The tall, graceful fronds of
+Matonia pectinata, forming miniature forests on the slopes of Mount Ophir
+and other districts in the Malay Peninsula in association with Dipteris
+conjugata and Dipteris lobbiana, represent a phase of Mesozoic life which
+survives 
+
+'Like a dim picture of the drowned past.'" ("Report of the 73rd Meeting of
+the British Assoc."  (Southport, 1903), London, 1904, page 844.)
+
+The Matonineae are ferns with an unusually complex vascular system and were
+abundant "in the northern hemisphere during the earlier part of the
+Mesozoic era."
+
+It was fortunate for science that Wallace took up the task which his
+colleague had abandoned.  Writing to him on the publication of his
+"Geographical Distribution of Animals" Darwin said:  "I feel sure that you
+have laid a broad and safe foundation for all future work on Distribution.
+How interesting it will be to see hereafter plants treated in strict
+relation to your views."  ("More Letters", II. page 12.)  This hope was
+fulfilled in "Island Life".  I may quote a passage from it which admirably
+summarises the contrast between the northern and the southern floras.
+
+"Instead of the enormous northern area, in which highly organised and
+dominant groups of plants have been developed gifted with great colonising
+and aggressive powers, we have in the south three comparatively small and
+detached areas, in which rich floras have been developed with SPECIAL
+adaptations to soil, climate, and organic environment, but comparatively
+impotent and inferior beyond their own domain."  (Wallace, "Island Life",
+pages 527, 528.)
+
+It will be noticed that in the summary I have attempted to give of the
+history of the subject, efforts have been concentrated on bringing into
+relation the temperate floras of the northern and southern hemispheres, but
+no account has been taken of the rich tropical vegetation which belts the
+world and little to account for the original starting-point of existing
+vegetation generally.  It must be remembered on the one hand that our
+detailed knowledge of the floras of the tropics is still very incomplete
+and far inferior to that of temperate regions; on the other hand
+palaeontological discoveries have put the problem in an entirely new light. 
+Well might Darwin, writing to Heer in 1875, say:  "Many as have been the
+wonderful discoveries in Geology during the last half-century, I think none
+have exceeded in interest your results with respect to the plants which
+formerly existed in the arctic regions."  ("More Letters", II. page 240.)
+
+As early as 1848 Debey had described from the Upper Cretaceous rocks of
+Aix-la-Chapelle Flowering plants of as high a degree of development as
+those now existing.  The fact was commented upon by Hooker ("Introd. Essay
+to the Flora of Tasmania", page xx.), but its full significance seems to
+have been scarcely appreciated.  For it implied not merely that their
+evolution must have taken place but the foundations of existing
+distribution must have been laid in a preceding age.  We now know from the
+discoveries of the last fifty years that the remains of the Neocomian flora
+occur over an area extending through 30 deg of latitude.  The conclusion is
+irresistible that within this was its centre of distribution and probably
+of origin.
+
+Darwin was immensely impressed with the outburst on the world of a fully
+fledged angiospermous vegetation.  He warmly approved the brilliant theory
+of Saporta that this happened "as soon (as) flower-frequenting insects were
+developed and favoured intercrossing."  ("More Letters", II. page 21.) 
+Writing to him in 1877 he says:  "Your idea that dicotyledonous plants were
+not developed in force until sucking insects had been evolved seems to me a
+splendid one.  I am surprised that the idea never occurred to me, but this
+is always the case when one first hears a new and simple explanation of
+some mysterious phenomenon."  ("Life and Letters", III. page 285. 
+Substantially the same idea had occurred earlier to F.W.A. Miquel. 
+Remarking that "sucking insects (Haustellata)...perform in nature the
+important duty of maintaining the existence of the vegetable kingdom, at
+least as far as the higher orders are concerned," he points our that "the
+appearance in great numbers of haustellate insects occurs at and after the
+Cretaceous epoch, when the plants with pollen and closed carpels
+(Angiosperms) are found, and acquire little by little the preponderance in
+the vegetable kingdom."  "Archives Neerlandaises", III. (1868).  English
+translation in "Journ. of Bot." 1869, page 101.)
+
+Even with this help the abruptness still remains an almost insoluble
+problem, though a forecast of floral structure is now recognised in some
+Jurassic and Lower Cretaceous plants.  But the gap between this and the
+structural complexity and diversity of angiosperms is enormous.  Darwin
+thought that the evolution might have been accomplished during a period of
+prolonged isolation.  Writing to Hooker (1881) he says:  "Nothing is more
+extraordinary in the history of the Vegetable Kingdom, as it seems to me,
+than the APPARENTLY very sudden or abrupt development of the higher plants.
+I have sometimes speculated whether there did not exist somewhere during
+long ages an extremely isolated continent, perhaps near the South Pole." 
+("Life and Letters", III. page 248.)
+
+The present trend of evidence is, however, all in favour of a northern
+origin for flowering plants, and we can only appeal to the imperfection of
+the geological record as a last resource to extricate us from the
+difficulty of tracing the process.  But Darwin's instinct that at some time
+or other the southern hemisphere had played an important part in the
+evolution of the vegetable kingdom did not mislead him.  Nothing probably
+would have given him greater satisfaction than the masterly summary in
+which Seward has brought together the evidence for the origin of the
+Glossopteris flora in Gondwana land.
+
+"A vast continental area, of which remnants are preserved in Australia,
+South Africa and South America...A tract of enormous extent occupying an
+area, part of which has since given place to a southern ocean, while
+detached masses persist as portions of more modern continents, which have
+enabled us to read in their fossil plants and ice-scratched boulders the
+records of a lost continent, in which the Mesozoic vegetation of the
+northern continent had its birth."  ("Encycl. Brit." (10th edition 1902),
+Vol. XXXI. ("Palaeobotany; Mesozoic"), page 422.)  Darwin would probably
+have demurred on physical grounds to the extent of the continent, and
+preferred to account for the transoceanic distribution of its flora by the
+same means which must have accomplished it on land.
+
+It must in fairness be added that Guppy's later views give some support to
+the conjectural existence of the "lost continent."  "The distribution of
+the genus Dammara" (Agathis) led him to modify his earlier conclusions.  He
+tells us:--"In my volume on the geology of Vanua Levu it was shown that the
+Tertiary period was an age of submergence in the Western Pacific, and a
+disbelief in any previous continental condition was expressed.  My later
+view is more in accordance with that of Wichmann, who, on geological
+grounds, contended that the islands of the Western Pacific were in a
+continental condition during the Palaeozoic and Mesozoic periods, and that
+their submergence and subsequent emergence took place in Tertiary times." 
+(Guppy, op. cit. II. page 304.)
+
+The weight of the geological evidence I am unable to scrutinise.  But
+though I must admit the possibility of some unconscious bias in my own mind
+on the subject, I am impressed with the fact that the known distribution of
+the Glossopteris flora in the southern hemisphere is precisely paralleled
+by that of Proteaceae and Restiaceae in it at the present time.  It is not
+unreasonable to suppose that both phenomena, so similar, may admit of the
+same explanation.  I confess it would not surprise me if fresh discoveries
+in the distribution of the Glossopteris flora were to point to the
+possibility of its also having migrated southwards from a centre of origin
+in the northern hemisphere.
+
+Darwin, however, remained sceptical "about the travelling of plants from
+the north EXCEPT DURING THE TERTIARY PERIOD."  But he added, "such
+speculations seem to me hardly scientific, seeing how little we know of the
+old floras."  ("Life and Letters", III. page 247.)  That in later
+geological times the south has been the grave of the weakened offspring of
+the aggressive north can hardly be doubted.  But if we look to the
+Glossopteris flora for the ancestry of Angiosperms during the Secondary
+period, Darwin's prevision might be justified, though he has given us no
+clue as to how he arrived at it.
+
+It may be true that technically Darwin was not a botanist.  But in two
+pages of the "Origin" he has given us a masterly explanation of "the
+relationship, with very little identity, between the productions of North
+America and Europe."  (Pages 333, 334.)  He showed that this could be
+accounted for by their migration southwards from a common area, and he told
+Wallace that he "doubted much whether the now called Palaearctic and
+Neartic regions ought to be separated."  ("Life and Letters", III. page
+230.)  Catkin-bearing deciduous trees had long been seen to justify
+Darwin's doubt:  oaks, chestnuts, beeches, hazels, hornbeams, birches,
+alders, willows and poplars are common both to the Old and New World. 
+Newton found that the separate regions could not be sustained for birds,
+and he is now usually followed in uniting them as the Holartic.  One feels
+inclined to say in reading the two pages, as Lord Kelvin did to a
+correspondent who asked for some further development of one of his papers,
+It is all there.  We have only to apply the principle to previous
+geological ages to understand why the flora of the Southern United States
+preserves a Cretaceous facies.  Applying it still further we can understand
+why, when the northern hemisphere gradually cooled through the Tertiary
+period, the plants of the Eocene "suggest a comparison of the climate and
+forests with those of the Malay Archipelago and Tropical America." 
+(Clement Reid, "Encycl. Brit." (10th edition), Vol. XXXI.  ("Palaeobotany;
+Tertiary"), page 435.)  Writing to Asa Gray in 1856 with respect to the
+United States flora, Darwin said that "nothing has surprised me more than
+the greater generic and specific affinity with East Asia than with West
+America."  ("More Letters", I. page 434.)  The recent discoveries of a
+Tulip tree and a Sassafras in China afford fresh illustrations.  A few
+years later Asa Gray found the explanation in both areas being centres of
+preservation of the Cretaceous flora from a common origin.  It is
+interesting to note that the paper in which this was enunciated at once
+established his reputation.
+
+In Europe the latitudinal range of the great mountain chains gave the
+Miocene flora no chance of escape during the Glacial period, and the
+Mediterranean appears to have equally intercepted the flow of alpine plants
+to the Atlas.  (John Ball in Appendix G, page 438, in "Journal of a Tour in
+Morocco and the Great Atlas", J.D. Hooker and J. Ball, London, 1878.)  In
+Southern Europe the myrtle, the laurel, the fig and the dwarf-palm are the
+sole representatives of as many great tropical families.  Another great
+tropical family, the Gesneraceae has left single representatives from the
+Pyrenees to the Balkans; and in the former a diminutive yam still lingers.
+These are only illustrations of the evidence which constantly accumulates
+and which finds no rational explanation except that which Darwin has given
+to it.
+
+The theory of southward migration is the key to the interpretation of the
+geographical distribution of plants.  It derived enormous support from the
+researches of Heer and has now become an accepted commonplace.  Saporta in
+1888 described the vegetable kingdom as "emigrant pour suivre une direction
+determinee et marcher du nord au sud, a la recherche de regions et de
+stations plus favorables, mieux appropriees aux adaptations acquises, a
+meme que la temperature terrestre perd ses conditions premieres." 
+("Origine Paleontologique des arbres", Paris, 1888, page 28.)  If, as is so
+often the case, the theory now seems to be a priori inevitable, the
+historian of science will not omit to record that the first germ sprang
+from the brain of Darwin.
+
+In attempting this sketch of Darwin's influence on Geographical
+Distribution, I have found it impossible to treat it from an external point
+of view.  His interest in it was unflagging; all I could say became
+necessarily a record of that interest and could not be detached from it. 
+He was in more or less intimate touch with everyone who was working at it.
+In reading the letters we move amongst great names.  With an extraordinary
+charm of persuasive correspondence he was constantly suggesting,
+criticising and stimulating.  It is hardly an exaggeration to say that from
+the quiet of his study at Down he was founding and directing a wide-world
+school.
+
+POSTSCRIPTUM.
+
+Since this essay was put in type Dr Ernst's striking account of the "New
+Flora of the Volcanic Island of Krakatau" (Cambridge, 1909.) has reached
+me.  All botanists must feel a debt of gratitude to Prof. Seward for his
+admirable translation of a memoir which in its original form is practically
+unprocurable and to the liberality of the Cambridge University Press for
+its publication.  In the preceding pages I have traced the laborious
+research by which the methods of Plant Dispersal were established by
+Darwin.  In the island of Krakatau nature has supplied a crucial experiment
+which, if it had occurred earlier, would have at once secured conviction of
+their efficiency.  A quarter of a century ago every trace of organic life
+in the island was "destroyed and buried under a thick covering of glowing
+stones."  Now, it is "again covered with a mantle of green, the growth
+being in places so luxuriant that it is necessary to cut one's way
+laboriously through the vegetation."  (Op. cit. page 4.)  Ernst traces
+minutely how this has been brought about by the combined action of wind,
+birds and sea currents, as means of transport.  The process will continue,
+and he concludes:--"At last after a long interval the vegetation on the
+desolated island will again acquire that wealth of variety and luxuriance
+which we see in the fullest development which Nature has reached in the
+primaeval forest in the tropics."  (Op. cit. page 72.)  The possibility of
+such a result revealed itself to the insight of Darwin with little
+encouragement or support from contemporary opinion.
+
+One of the most remarkable facts established by Ernst is that this has not
+been accomplished by the transport of seeds alone.  "Tree stems and
+branches played an important part in the colonisation of Krakatau by plants
+and animals.  Large piles of floating trees, stems, branches and bamboos
+are met with everywhere on the beach above high-water mark and often
+carried a considerable distance inland.  Some of the animals on the island,
+such as the fat Iguana (Varanus salvator) which suns itself in the beds of
+streams, may have travelled on floating wood, possibly also the ancestors
+of the numerous ants, but certainly plants."  (Op. cit. page 56.)  Darwin
+actually had a prevision of this.  Writing to Hooker he says:--"Would it
+not be a prodigy if an unstocked island did not in the course of ages
+receive colonists from coasts whence the currents flow, trees are drifted
+and birds are driven by gales?"  ("More Letters", I. page 483.)  And ten
+years earlier:--"I must believe in the...whole plant or branch being washed
+into the sea; with floods and slips and earthquakes; this must continually
+be happening."  ("Life and Letters", II. pages 56, 57.)  If we give to
+"continually" a cosmic measure, can the fact be doubted?  All this, in the
+light of our present knowledge, is too obvious to us to admit of
+discussion.  But it seems to me nothing less than pathetic to see how in
+the teeth of the obsession as to continental extension, Darwin fought
+single-handed for what we now know to be the truth.
+
+Guppy's heart failed him when he had to deal with the isolated case of
+Agathis which alone seemed inexplicable by known means of transport.  But
+when we remember that it is a relic of the pre-Angiospermous flora, and is
+of Araucarian ancestry, it cannot be said that the impossibility, in so
+prolonged a history, of the bodily transference of cone-bearing branches or
+even of trees, compels us as a last resort to fall back on continental
+extension to account for its existing distribution.
+
+When Darwin was in the Galapagos Archipelago, he tells us that he fancied
+himself "brought near to the very act of creation."  He saw how new species
+might arise from a common stock.  Krakatau shows us an earlier stage and
+how by simple agencies, continually at work, that stock might be supplied.
+It also shows us how the mixed and casual elements of a new colony enter
+into competition for the ground and become mutually adjusted.  The study of
+Plant Distribution from a Darwinian standpoint has opened up a new field of
+research in Ecology.  The means of transport supply the materials for a
+flora, but their ultimate fate depends on their equipment for the "struggle
+for existence."  The whole subject can no longer be regarded as a mere
+statistical inquiry which has seemed doubtless to many of somewhat arid
+interest.  The fate of every element of the earth's vegetation has sooner
+or later depended on its ability to travel and to hold its own under new
+conditions.  And the means by which it has secured success is an each case
+a biological problem which demands and will reward the most attentive
+study.  This is the lesson which Darwin has bequeathed to us.  It is summed
+up in the concluding paragraph of the "Origin" ("Origin of Species" (6th
+edition), page 429.):--"It is interesting to contemplate a tangled bank,
+clothed with many plants of many kinds, with birds singing on the bushes,
+with various insects flitting about, and with worms crawling through the
+damp earth, and to reflect that these elaborately constructed forms, so
+different from each other, and dependent upon each other in so complex a
+manner, have all been produced by laws acting around us."
+
+
+XVII.  GEOGRAPHICAL DISTRIBUTION OF ANIMALS.
+
+By HANS GADOW, M.A., Ph.D., F.R.S.
+Strickland Curator and Lecturer on Zoology in the University of Cambridge.
+
+The first general ideas about geographical distribution may be found in
+some of the brilliant speculations contained in Buffon's "Histoire
+Naturelle".  The first special treatise on the subject was however written
+in 1777 by E.A.W. Zimmermann, Professor of Natural Science at Brunswick,
+whose large volume, "Specimen Zoologiae Geographicae Quadrupedum"..., deals
+in a statistical way with the mammals; important features of the large
+accompanying map of the world are the ranges of mountains and the names of
+hundreds of genera indicating their geographical range.  In a second work
+he laid special stress on domesticated animals with reference to the
+spreading of the various races of Mankind.
+
+In the following year appeared the "Philosophia Entomologica" by J.C.
+Fabricius, who was the first to divide the world into eight regions.  In
+1803 G.R. Treviranus ("Biologie oder Philosophie der lebenden Natur", Vol.
+II. Gottingen, 1803.) devoted a long chapter of his great work on
+"Biologie" to a philosophical and coherent treatment of the distribution of
+the whole animal kingdom.  Remarkable progress was made in 1810 by F.
+Tiedemann ("Anatomie und Naturgeschichte der Vogel".  Heidelberg, 1810.) of
+Heidelberg.  Few, if any, of the many subsequent Ornithologists seem to
+have appreciated, or known of, the ingenious way in which Tiedemann
+marshalled his statistics in order to arrive at general conclusions.  There
+are, for instance, long lists of birds arranged in accordance with their
+occurrence in one or more continents:  by correlating the distribution of
+the birds with their food he concludes "that the countries of the East
+Indian flora have no vegetable feeders in common with America," and "that
+it is probably due to the great peculiarity of the African flora that
+Africa has few phytophagous kinds in common with other countries, whilst
+zoophagous birds have a far more independent, often cosmopolitan,
+distribution."  There are also remarkable chapters on the influence of
+environment, distribution, and migration, upon the structure of the Birds! 
+In short, this anatomist dealt with some of the fundamental causes of
+distribution.
+
+Whilst Tiedemann restricted himself to Birds, A. Desmoulins in 1822 wrote a
+short but most suggestive paper on the Vertebrata, omitting the birds; he
+combated the view recently proposed by the entomologist Latreille that
+temperature was the main factor in distribution.  Some of his ten main
+conclusions show a peculiar mixture of evolutionary ideas coupled with the
+conception of the stability of species:  whilst each species must have
+started from but one creative centre, there may be several "analogous
+centres of creation" so far as genera and families are concerned. 
+Countries with different faunas, but lying within the same climatic zones,
+are proof of the effective and permanent existence of barriers preventing
+an exchange between the original creative centres.
+
+The first book dealing with the "geography and classification" of the whole
+animal kingdom was written by W. Swainson ("A Treatise on the Geography and
+Classification of Animals", Lardner's "Cabinet Cyclopaedia" London, 1835.)
+in 1835.  He saw in the five races of Man the clue to the mapping of the
+world into as many "true zoological divisions," and he reconciled the five
+continents with his mystical quinary circles.
+
+Lyell's "Principles of Geology" should have marked a new epoch, since in
+his "Elements" he treats of the past history of the globe and the
+distribution of animals in time, and in his "Principles" of their
+distribution in space in connection with the actual changes undergone by
+the surface of the world.  But as the sub-title of his great work "Modern
+changes of the Earth and its inhabitants" indicates, he restricted himself
+to comparatively minor changes, and, emphatically believing in the
+permanency of the great oceans, his numerous and careful interpretations of
+the effect of the geological changes upon the dispersal of animals did
+after all advance the problem but little.
+
+Hitherto the marine faunas had been neglected.  This was remedied by E.
+Forbes, who established nine homozoic zones, based mainly on the study of
+the mollusca, the determining factors being to a great extent the isotherms
+of the sea, whilst the 25 provinces were given by the configuration of the
+land.  He was followed by J.D. Dana, who, taking principally the Crustacea
+as a basis, and as leading factors the mean temperatures of the coldest and
+of the warmest months, established five latitudinal zones.  By using these
+as divisors into an American, Afro-European, Oriental, Arctic and Antarctic
+realm, most of which were limited by an eastern and western land-boundary,
+he arrived at about threescore provinces.
+
+In 1853 appeared L.K. Schmarda's ("Die geographische Verbreitung der
+Thiere", Wien, 1853.) two volumes, embracing the whole subject.  Various
+centres of creation being, according to him, still traceable, he formed the
+hypothesis that these centres were originally islands, which later became
+enlarged and joined together to form the great continents, so that the
+original faunas could overlap and mix whilst still remaining pure at their
+respective centres.  After devoting many chapters to the possible physical
+causes and modes of dispersal, he divided the land into 21 realms which he
+shortly characterises, e.g. Australia as the only country inhabited by
+marsupials, monotremes and meliphagous birds.  Ten main marine divisions
+were diagnosed in a similar way.  Although some of these realms were not
+badly selected from the point of view of being applicable to more than one
+class of animals, they were obviously too numerous for general purposes,
+and this drawback was overcome, in 1857, by P.L. Sclater.  ("On the general
+Geographical Distribution of the members of the class Aves", "Proc. Linn.
+Soc." (Zoology II. 1858, pages 130-145.)  Starting with the idea, that
+"each species must have been created within and over the geographical area,
+which it now occupies," he concluded "that the most natural primary
+ontological divisions of the Earth's surface" were those six regions, which
+since their adoption by Wallace in his epoch-making work, have become
+classical.  Broadly speaking, these six regions are equivalent to the great
+masses of land; they are convenient terms for geographical facts,
+especially since the Palaearctic region expresses the unity of Europe with
+the bulk of Asia.  Sclater further brigaded the regions of the Old World as
+Palaeogaea and the two Americas as Neogaea, a fundamental mistake,
+justifiable to a certain extent only since he based his regions mainly upon
+the present distribution of the Passerine birds.
+
+Unfortunately these six regions are not of equal value.  The Indian
+countries and the Ethiopian region (Africa south of the Sahara) are
+obviously nothing but the tropical, southern continuations or appendages of
+one greater complex.  Further, the great eastern mass of land is so
+intimately connected with North America that this continent has much more
+in common with Europe and Asia than with South America.  Therefore, instead
+of dividing the world longitudinally as Sclater had done, Huxley, in 1868
+("On the classification and distribution of the Alectoromorphae and
+Heteromorphae", "Proc. Zool. Soc." 1868, page 294.), gave weighty reasons
+for dividing it transversely.  Accordingly he established two primary
+divisions, Arctogaea or the North world in a wider sense, comprising
+Sclater's Indian, African, Palaearctic and Neartic regions; and Notogaea,
+the Southern world, which he divided into (1) Austro-Columbia (an
+unfortunate substitute for the neotropical region), (2) Australasia, and
+(3) New Zealand, the number of big regions thus being reduced to three but
+for the separation of New Zealand upon rather negative characters.  Sclater
+was the first to accept these four great regions and showed, in 1874 ("The
+geographical distribution of Mammals", "Manchester Science Lectures",
+1874.), that they were well borne out by the present distribution of the
+Mammals.
+
+Although applicable to various other groups of animals, for instance to the
+tailless Amphibia and to Birds (Huxley himself had been led to found his
+two fundamental divisions on the distribution of the Gallinaceous birds),
+the combination of South America with Australia was gradually found to be
+too sweeping a measure.  The obvious and satisfactory solution was provided
+by W.T. Blanford (Anniversary address (Geological Society, 1889), "Proc.
+Geol. Soc." 1889-90, page 67; "Quart. Journ." XLVI 1890.), who in 1890
+recognised three main divisions, namely Australian, South American, and the
+rest, for which the already existing terms (although used partly in a new
+sense, as proposed by an anonymous writer in "Natural Science", III. page
+289) "Notogaea," "Neogaea" and "Arctogaea" have been gladly accepted by a
+number of English writers.
+
+After this historical survey of the search for larger and largest or
+fundamental centres of animal creation, which resulted in the mapping of
+the world into zoological regions and realms of after all doubtful value,
+we have to return to the year 1858.  The eleventh and twelfth chapters of
+"The Origin of Species" (1859), dealing with "Geographical Distribution,"
+are based upon a great amount of observation, experiment and reading.  As
+Darwin's main problem was the origin of species, nature's way of making
+species by gradual changes from others previously existing, he had to
+dispose of the view, held universally, of the independent creation of each
+species and at the same time to insist upon a single centre of creation for
+each species; and in order to emphasise his main point, the theory of
+descent, he had to disallow convergent, or as they were then called,
+analogous forms.  To appreciate the difficulty of his position we have to
+take the standpoint of fifty years ago, when the immutability of the
+species was an axiom and each was supposed to have been created within or
+over the geographical area which it now occupies.  If he once admitted that
+a species could arise from many individuals instead of from one pair, there
+was no way of shutting the door against the possibility that these
+individuals may have been so numerous that they occupied a very large
+district, even so large that it had become as discontinuous as the
+distribution of many a species actually is.  Such a concession would at
+once be taken as an admission of multiple, independent, origin instead of
+descent in Darwin's sense.
+
+For the so-called multiple, independently repeated creation of species as
+an explanation of their very wide and often quite discontinuous
+distribution, he substituted colonisation from the nearest and readiest
+source together with subsequent modification and better adaptation to their
+new home.
+
+He was the first seriously to call attention to the many accidental means,
+"which more properly should be called occasional means of distribution,"
+especially to oceanic islands.  His specific, even individual, centres of
+creation made migrations all the more necessary, but their extent was sadly
+baulked by the prevailing dogma of the permanency of the oceans.  Any
+number of small changes ("many islands having existed as halting places, of
+which not a wreck now remains" ("The Origin of Species" (1st edition), page
+396.).) were conceded freely, but few, if any, great enough to permit
+migration of truly terrestrial creatures.  The only means of getting across
+the gaps was by the principle of the "flotsam and jetsam," a theory which
+Darwin took over from Lyell and further elaborated so as to make it
+applicable to many kinds of plants and animals, but sadly deficient, often
+grotesque, in the case of most terrestrial creatures.
+
+Another very fertile source was Darwin's strong insistence upon the great
+influence which the last glacial epoch must have had upon the distribution
+of animals and plants.  Why was the migration of northern creatures
+southwards of far-reaching and most significant importance?  More
+northerners have established themselves in southern lands than vice versa,
+because there is such a great mass of land in the north and greater
+continents imply greater intensity of selection.  "The productions of real
+islands have everywhere largely yielded to continental forms."  (Ibid. page
+380.)..."The Alpine forms have almost everywhere largely yielded to the
+more dominant forms generated in the larger areas and more efficient
+workshops of the North."
+
+Let us now pass in rapid survey the influence of the publication of "The
+Origin of Species" upon the study of Geographical Distribution in its wider
+sense.
+
+Hitherto the following thought ran through the minds of most writers: 
+Wherever we examine two or more widely separated countries their respective
+faunas are very different, but where two faunas can come into contact with
+each other, they intermingle.  Consequently these faunas represent centres
+of creation, whence the component creatures have spread peripherally so far
+as existing boundaries allowed them to do so.  This is of course the
+fundamental idea of "regions."  There is not one of the numerous writers
+who considered the possibility that these intermediate belts might
+represent not a mixture of species but transitional forms, the result of
+changes undergone by the most peripheral migrants in adaptation to their
+new surroundings.  The usual standpoint was also that of Pucheran ("Note
+sur l'equateur zoologique", "Rev. et Mag. de Zoologie", 1855; also several
+other papers, ibid. 1865, 1866, and 1867.) in 1855.  But what a change
+within the next ten years!  Pucheran explains the agreement in coloration
+between the desert and its fauna as "une harmonie post-etablie"; the
+Sahara, formerly a marine basin, was peopled by immigrants from the
+neighbouring countries, and these new animals adapted themselves to the new
+environment.  He also discusses, among other similar questions, the Isthmus
+of Panama with regard to its having once been a strait.  From the same
+author may be quoted the following passage as a strong proof of the new
+influence:  "By the radiation of the contemporaneous faunas, each from one
+centre, whence as the various parts of the world successively were formed
+and became habitable, they spread and became modified according to the
+local physical conditions."
+
+The "multiple" origin of each species as advocated by Sclater and Murray,
+although giving the species a broader basis, suffered from the same
+difficulties.  There was only one alternative to the old orthodox view of
+independent creation, namely the bold acceptance of land-connections to an
+extent for which geological and palaeontological science was not yet ripe.
+Those who shrank from either view, gave up the problem as mysterious and
+beyond the human intellect.  This was the expressed opinion of men like
+Swainson, Lyell and Humboldt.  Only Darwin had the courage to say that the
+problem was not insoluble.  If we admit "that in the long course of time
+the individuals of the same species, and likewise of allied species, have
+proceeded from some one source; then I think all the grand leading facts of
+geographical distribution are explicable on the theory of
+migration...together with subsequent modification and the multiplication of
+new forms."  We can thus understand how it is that in some countries the
+inhabitants "are linked to the extinct beings which formerly inhabited the
+same continent."  We can see why two areas, having nearly the same physical
+conditions, should often be inhabited by very different forms of
+life,...and "we can see why in two areas, however distant from each other,
+there should be a correlation, in the presence of identical species...and
+of distinct but representative species."  ("The Origin of Species" (1st
+edition), pages 408, 409.)
+
+Darwin's reluctance to assume great geological changes, such as a land-
+connection of Europe with North America, is easily explained by the fact
+that he restricted himself to the distribution of the present and
+comparatively recent species.  "I do not believe that it will ever be
+proved that within the recent period continents which are now quite
+separate, have been continuously, or almost continuously, united with each
+other, and with the many existing oceanic islands."  (Ibid. page 357.) 
+Again, "believing...that our continents have long remained in nearly the
+same relative position, though subjected to large, but partial oscillations
+of level," that means to say within the period of existing species, or
+"within the recent period."  (Ibid. page. 370.)  The difficulty was to a
+great extent one of his own making.  Whilst almost everybody else believed
+in the immutability of the species, which implies an enormous age,
+logically since the dawn of creation, to him the actually existing species
+as the latest results of evolution, were necessarily something very new, so
+young that only the very latest of the geological epochs could have
+affected them.  It has since come to our knowledge that a great number of
+terrestrial "recent" species, even those of the higher classes of
+Vertebrates, date much farther back than had been thought possible.  Many
+of them reach well into the Miocene, a time since which the world seems to
+have assumed the main outlines of the present continents.
+
+In the year 1866 appeared A. Murray's work on the "Geographical
+Distribution of Mammals", a book which has perhaps received less
+recognition than it deserves.  His treatment of the general introductory
+questions marks a considerable advance of our problem, although, and partly
+because, he did not entirely agree with Darwin's views as laid down in the
+first edition of "The Origin of Species", which after all was the great
+impulse given to Murray's work.  Like Forbes he did not shrink from
+assuming enormous changes in the configuration of the continents and oceans
+because the theory of descent, with its necessary postulate of great
+migrations, required them.  He stated, for instance, "that a Miocene
+Atlantis sufficiently explains the common distribution of animals and
+plants in Europe and America up to the glacial epoch."  And next he
+considers how, and by what changes, the rehabilitation and distribution of
+these lands themselves were effected subsequent to that period.  Further,
+he deserves credit for having cleared up a misunderstanding of the idea of
+specific centres of creation.  Whilst for instance Schmarda assumed without
+hesitation that the same species, if occurring at places separated by great
+distances, or apparently insurmountable barriers, had been there created
+independently (multiple centres), Lyell and Darwin held that each species
+had only one single centre, and with this view most of us agree, but their
+starting point was to them represented by one individual, or rather one
+single pair.  According to Murray, on the other hand, this centre of a
+species is formed by all the individuals of a species, all of which equally
+undergo those changes which new conditions may impose upon them.  In this
+respect a new species has a multiple origin, but this in a sense very
+different from that which was upheld by L. Agassiz.  As Murray himself puts
+it:  "To my multiple origin, communication and direct derivation is
+essential.  The species is compounded of many influences brought together
+through many individuals, and distilled by Nature into one species; and,
+being once established it may roam and spread wherever it finds the
+conditions of life not materially different from those of its original
+centre."  (Murray, "The Geographical Distribution of Mammals", page 14. 
+London, 1866.)  This declaration fairly agrees with more modern views, and
+it must be borne in mind that the application of the single-centre
+principle to the genera, families and larger groups in the search for
+descent inevitably leads to one creative centre for the whole animal
+kingdom, a condition as unwarrantable as the myth of Adam and Eve being the
+first representatives of Mankind.
+
+It looks as if it had required almost ten years for "The Origin of Species"
+to show its full effect, since the year 1868 marks the publication of
+Haeckel's "Naturliche Schoepfungsgeschichte" in addition to other great
+works.  The terms "Oecology" (the relation of organisms to their
+environment) and "Chorology" (their distribution in space) had been given
+us in his "Generelle Morphologie" in 1866.  The fourteenth chapter of the
+"History of Creation" is devoted to the distribution of organisms, their
+chorology, with the emphatic assertion that "not until Darwin can chorology
+be spoken of as a separate science, since he supplied the acting causes for
+the elucidation of the hitherto accumulated mass of facts."  A map (a
+"hypothetical sketch") shows the monophyletic origin and the routes of
+distribution of Man.
+
+Natural Selection may be all-mighty, all-sufficient, but it requires time,
+so much that the countless aeons required for the evolution of the present
+fauna were soon felt to be one of the most serious drawbacks of the theory. 
+Therefore every help to ease and shorten this process should have been
+welcomed.  In 1868 M. Wagner (The first to formulate clearly the
+fundamental idea of a theory of migration and its importance in the origin
+of new species was L. von Buch, who in his "Physikalische Beschreibung der
+Canarischen Inseln", written in 1825, wrote as follows:  "Upon the
+continents the individuals of the genera by spreading far, form, through
+differences of the locality, food and soil, varieties which finally become
+constant as new species, since owing to the distances they could never be
+crossed with other varieties and thus be brought back to the main type. 
+Next they may again, perhaps upon different roads, return to the old home
+where they find the old type likewise changed, both having become so
+different that they can interbreed no longer.  Not so upon islands, where
+the individuals shut up in narrow valleys or within narrow districts, can
+always meet one another and thereby destroy every new attempt towards the
+fixing of a new variety."  Clearly von Buch explains here why island types
+remain fixed, and why these types themselves have become so different from
+their continental congeners.--Actually von Buch is aware of a most
+important point, the difference in the process of development which exists
+between a new species b, which is the result of an ancestral species a
+having itself changed into b and thereby vanished itself, and a new species
+c which arose through separation out of the same ancestral a, which itself
+persists as such unaltered.  Von Buch's prophetic view seems to have
+escaped Lyell's and even Wagner's notice.) came to the rescue with his
+"Darwin'sche Theorie und das Migrations-Gesetz der Organismen".  (Leipzig,
+1868.)  He shows that migration, i.e. change of locality, implies new
+environmental conditions (never mind whether these be new stimuli to
+variation, or only acting as their selectors or censors), and moreover
+secures separation from the original stock and thus eliminates or lessens
+the reactionary dangers of panmixia.  Darwin accepted Wagner's theory as
+"advantageous."  Through the heated polemics of the more ardent
+selectionists Wagner's theory came to grow into an alternative instead of a
+help to the theory of selectional evolution.  Separation is now rightly
+considered a most important factor by modern students of geographical
+distribution.
+
+For the same year, 1868, we have to mention Huxley, whose Arctogaea and
+Notogaea are nothing less than the reconstructed main masses of land of the
+Mesozoic period.  Beyond doubt the configuration of land at that remote
+period has left recognisable traces in the present continents, but whether
+they can account for the distribution of such a much later group as the
+Gallinaceous birds is more than questionable.  In any case he took for his
+text a large natural group of birds, cosmopolitan as a whole, but with a
+striking distribution.  The Peristeropodes, or pigeon-footed division, are
+restricted to the Australian and Neotropical regions, in distinction to the
+Alectoropodes (with the hallux inserted at a level above the front toes)
+which inhabit the whole of the Arctogaea, only a few members having spread
+into the South World.  Further, as Asia alone has its Pheasants and allies,
+so is Africa characterised by its Guinea-fowls and relations, America has
+the Turkey as an endemic genus, and the Grouse tribe in a wider sense has
+its centre in the holarctic region:  a splendid object lesson of descent,
+world-wide spreading and subsequent differentiation.  Huxley, by the way,
+was the first--at least in private talk--to state that it will be for the
+morphologist, the well-trained anatomist, to give the casting vote in
+questions of geographical distribution, since he alone can determine
+whether we have to deal with homologous, or analogous, convergent,
+representative forms.
+
+It seems late to introduce Wallace's name in 1876, the year of the
+publication of his standard work.  ("The Geographical Distribution of
+Animals", 2 vols.  London, 1876.)  We cannot do better than quote the
+author's own words, expressing the hope that his "book should bear a
+similar relation to the eleventh and twelfth chapters of the "Origin of
+Species" as Darwin's "Animals and Plants under Domestication" does to the
+first chapter of that work," and to add that he has amply succeeded. 
+Pleading for a few primary centres he accepts Sclater's six regions and
+does not follow Huxley's courageous changes which Sclater himself had
+accepted in 1874.  Holding the view of the permanence of the oceans he
+accounts for the colonisation of outlying islands by further elaborating
+the views of Lyell and Darwin, especially in his fascinating "Island Life",
+with remarkable chapters on the Ice Age, Climate and Time and other
+fundamental factors.  His method of arriving at the degree of relationship
+of the faunas of the various regions is eminently statistical.  Long lists
+of genera determine by their numbers the affinity and hence the source of
+colonisation.  In order to make sure of his material he performed the
+laborious task of evolving a new classification of the host of Passerine
+birds.  This statistical method has been followed by many authors, who,
+relying more upon quantity than quality, have obscured the fact that the
+key to the present distribution lies in the past changes of the earth's
+surface.  However, with Wallace begins the modern study of the geographical
+distribution of animals and the sudden interest taken in this subject by an
+ever widening circle of enthusiasts far beyond the professional
+brotherhood.
+
+A considerable literature has since grown up, almost bewildering in its
+range, diversity of aims and style of procedure.  It is a chaos, with many
+paths leading into the maze, but as yet very few take us to a position
+commanding a view of the whole intricate terrain with its impenetrable
+tangle and pitfalls.
+
+One line of research, not initiated but greatly influenced by Wallace's
+works, became so prominent as to almost constitute a period which may be
+characterised as that of the search by specialists for either the
+justification or the amending of his regions.  As class after class of
+animals was brought up to reveal the secret of the true regions, some
+authors saw in their different results nothing but the faultiness of
+previously established regions; others looked upon eventual agreements as
+their final corroboration, especially when for instance such diverse groups
+as mammals and scorpions could, with some ingenuity, be made to harmonise. 
+But the obvious result of all these efforts was the growing knowledge that
+almost every class seemed to follow principles of its own.  The regions
+tallied neither in extent nor in numbers, although most of them gravitated
+more and more towards three centres, namely Australia, South America and
+the rest of the world.  Still zoologists persisted in the search, and the
+various modes and capabilities of dispersal of the respective groups were
+thought sufficient explanation of the divergent results in trying to bring
+the mapping of the world under one scheme.
+
+Contemporary literature is full of devices for the mechanical dispersal of
+animals.  Marine currents, warm and cold, were favoured all the more since
+they showed the probable original homes of the creatures in question.  If
+these could not stand sea-water, they floated upon logs or icebergs, or
+they were blown across by storms; fishes were lifted over barriers by
+waterspouts, and there is on record even an hypothetical land tortoise,
+full of eggs, which colonised an oceanic island after a perilous sea voyage
+upon a tree trunk.  Accidents will happen, and beyond doubt many freaks of
+discontinuous distribution have to be accounted for by some such means. 
+But whilst sufficient for the scanty settlers of true oceanic islands, they
+cannot be held seriously to account for the rich fauna of a large
+continent, over which palaeontology shows us that the immigrants have
+passed like waves.  It should also be borne in mind that there is a great
+difference between flotsam and jetsam.  A current is an extension of the
+same medium and the animals in it may suffer no change during even a long
+voyage, since they may be brought from one litoral to another where they
+will still be in the same or but slightly altered environment.  But the
+jetsam is in the position of a passenger who has been carried off by the
+wrong train.  Almost every year some American land birds arrive at our
+western coasts and none of them have gained a permanent footing although
+such visits must have taken place since prehistoric times.  It was
+therefore argued that only those groups of animals should be used for
+locating and defining regions which were absolutely bound to the soil. 
+This method likewise gave results not reconcilable with each other, even
+when the distribution of fossils was taken into account, but it pointed to
+the absolute necessity of searching for former land-connections regardless
+of their extent and the present depths to which they may have sunk.
+
+That the key to the present distribution lies in the past had been felt
+long ago, but at last it was appreciated that the various classes of
+animals and plants have appeared in successive geological epochs and also
+at many places remote from each other.  The key to the distribution of any
+group lies in the configuration of land and water of that epoch in which it
+made its first appearance.  Although this sounds like a platitude, it has
+frequently been ignored.  If, for argument's sake, Amphibia were evolved
+somewhere upon the great southern land-mass of Carboniferous times
+(supposed by some to have stretched from South America across Africa to
+Australia), the distribution of this developing class must have proceeded
+upon lines altogether different from that of the mammals which dated
+perhaps from lower Triassic times, when the old south continental belt was
+already broken up.  The broad lines of this distribution could never
+coincide with that of the other, older class, no matter whether the
+original mammalian centre was in the Afro-Indian, Australian, or Brazilian
+portion.  If all the various groups of animals had come into existence at
+the same time and at the same place, then it would be possible, with
+sufficient geological data, to construct a map showing the generalised
+results applicable to the whole animal kingdom.  But the premises are
+wrong.  Whatever regions we may seek to establish applicable to all
+classes, we are necessarily mixing up several principles, namely
+geological, historical, i.e. evolutionary, with present day statistical
+facts.  We might as well attempt one compound picture representing a
+chick's growth into an adult bird and a child's growth into manhood.
+
+In short there are no general regions, not even for each class separately,
+unless this class be one which is confined to a comparatively short
+geological period.  Most of the great classes have far too long a history
+and have evolved many successive main groups.  Let us take the mammals. 
+Marsupials live now in Australia and in both Americas, because they already
+existed in Mesozoic times; Ungulata existed at one time or other all over
+the world except in Australia, because they are post-Cretaceous;
+Insectivores, although as old as any Placentalia, are cosmopolitan
+excepting South America and Australia; Stags and Bears, as examples of
+comparatively recent Arctogaeans, are found everywhere with the exception
+of Ethiopia and Australia.  Each of these groups teaches a valuable
+historical lesson, but when these are combined into the establishment of a
+few mammalian "realms," they mean nothing but statistical majorities.  If
+there is one at all, Australia is such a realm backed against the rest of
+the world, but as certainly it is not a mammalian creative centre!
+
+Well then, if the idea of generally applicable regions is a mare's nest, as
+was the search for the Holy Grail, what is the object of the study of
+geographical distribution?  It is nothing less than the history of the
+evolution of life in space and time in the widest sense.  The attempt to
+account for the present distribution of any group of organisms involves the
+aid of every branch of science.  It bids fair to become a history of the
+world.  It started in a mild, statistical way, restricting itself to the
+present fauna and flora and to the present configuration of land and water. 
+Next came Oceanography concerned with the depths of the seas, their
+currents and temperatures; then enquiries into climatic changes,
+culminating in irreconcilable astronomical hypotheses as to glacial epochs;
+theories about changes of the level of the seas, mainly from the point of
+view of the physicist and astronomer.  Then came more and more to the front
+the importance of the geological record, hand in hand with the
+palaeontological data and the search for the natural affinities, the
+genetic system of the organisms.  Now and then it almost seems as if the
+biologists had done their share by supplying the problems and that the
+physicists and geologists would settle them, but in reality it is not so. 
+The biologists not only set the problems, they alone can check the offered
+solutions.  The mere fact of palms having flourished in Miocene Spitzbergen
+led to an hypothetical shifting of the axis of the world rather than to the
+assumption, by way of explanation, that the palms themselves might have
+changed their nature.  One of the most valuable aids in geological
+research, often the only means for reconstructing the face of the earth in
+by-gone periods, is afforded by fossils, but only the morphologist can
+pronounce as to their trustworthiness as witnesses, because of the danger
+of mistaking analogous for homologous forms.  This difficulty applies
+equally to living groups, and it is so important that a few instances may
+not be amiss.
+
+There is undeniable similarity between the faunas of Madagascar and South
+America.  This was supported by the Centetidae and Dendrobatidae, two
+entire "families," as also by other facts.  The value of the Insectivores,
+Solenodon in Cuba, Centetes in Madagascar, has been much lessened by their
+recognition as an extremely ancient group and as a case of convergence, but
+if they are no longer put into the same family, this amendment is really to
+a great extent due to their widely discontinuous distribution.  The only
+systematic difference of the Dendrobatidae from the Ranidae is the absence
+of teeth, morphologically a very unimportant character, and it is now
+agreed, on the strength of their distribution, that these little arboreal,
+conspicuously coloured frogs, Dendrobates in South America, Mantella in
+Madagascar, do not form a natural group, although a third genus,
+Cardioglossa in West Africa, seems also to belong to them.  If these
+creatures lived all on the same continent, we should unhesitatingly look
+upon them as forming a well-defined, natural little group.  On the other
+hand the Aglossa, with their three very divergent genera, namely Pipa in
+South America, Xenopus and Hymenochirus in Africa, are so well
+characterised as one ancient group that we use their distribution
+unhesitatingly as a hint of a former connection between the two continents. 
+We are indeed arguing in vicious circles.  The Ratitae as such are
+absolutely worthless since they are a most heterogeneous assembly, and
+there are untold groups, of the artificiality of which many a zoo-
+geographer had not the slightest suspicion when he took his statistical
+material, the genera and families, from some systematic catalogues or
+similar lists.  A lamentable instance is that of certain flightless Rails,
+recently extinct or sub-fossil, on the isalnds of Mauritius, Rodriguez and
+Chatham.  Being flightless they have been used in support of a former huge
+Antarctic continent, instead of ruling them out of court as Rails which,
+each in its island, have lost the power of flight, a process which must
+have taken place so recently that it is difficult, upon morphological
+grounds, to justify their separation into Aphanapteryx in Mauritius,
+Erythromachus in Rodriguez and Diaphorapteryx on Chatham Island. 
+Morphologically they may well form but one genus, since they have sprung
+from the same stock and have developed upon the same lines; they are
+therefore monogenetic:  but since we know that they have become what they
+are independently of each other (now unlike any other Rails), they are
+polygenetic and therefore could not form one genus in the old Darwinian
+sense.  Further, they are not a case of convergence, since their ancestry
+is not divergent but leads into the same stratum.
+
+THE RECONSTRUCTION OF THE GEOGRAPHY OF SUCCESSIVE EPOCHS.
+
+A promising method is the study by the specialist of a large, widely
+distributed group of animals from an evolutionary point of view.  Good
+examples of this method are afforded by A.E. Ortmann's ("The geographical
+distribution of Freshwater Decapods and its bearing upon ancient
+geography", "Proc. Amer. Phil. Soc." Vol. 41, 1902.) exhaustive paper and
+by A.W. Grabau's "Phylogeny of Fusus and its Allies" ("Smithsonian Misc.
+Coll." 44, 1904.)  After many important groups of animals have been treated
+in this way--as yet sparingly attempted--the results as to hypothetical
+land-connections etc. are sure to be corrective and supplementary, and
+their problems will be solved, since they are not imaginary.
+
+The same problems are attacked, in the reverse way, by starting with the
+whole fauna of a country and thence, so to speak, letting the research
+radiate.  Some groups will be considered as autochthonous, others as
+immigrants, and the directions followed by them will be inquired into; the
+search may lead far and in various directions, and by comparison of
+results, by making compound maps, certain routes will assume definite
+shape, and if they lead across straits and seas they are warrants to search
+for land-connections in the past.  (A fair sample of this method is C.H.
+Eigenmann's "The Freshwater Fishes of South and Middle America", "Popular
+Science Monthly", Vol. 68, 1906.)  There are now not a few maps purporting
+to show the outlines of land and water at various epochs.  Many of these
+attempts do not tally with each other, owing to the lamentable deficiencies
+of geological and fossil data, but the bolder the hypothetical outlines are
+drawn, the better, and this is preferable to the insertion of bays and
+similar detail which give such maps a fallacious look of certainty where
+none exists.  Moreover it must be borne in mind that, when we draw a broad
+continental belt across an ocean, this belt need never have existed in its
+entirety at any one time.  The features of dispersal, intended to be
+explained by it, would be accomplished just as well by an unknown number of
+islands which have joined into larger complexes while elsewhere they
+subsided again:  like pontoon-bridges which may be opened anywhere, or like
+a series of superimposed dissolving views of land and sea-scapes.  Hence
+the reconstructed maps of Europe, the only continent tolerably known, show
+a considerable number of islands in puzzling changes, while elsewhere, e.g.
+in Asia, we have to be satisfied with sweeping generalisations.
+
+At present about half-a-dozen big connections are engaging our attention,
+leaving as comparatively settled the extent and the duration of such minor
+"bridges" as that between Africa and Madagascar, Tasmania and Australia,
+the Antilles and Central America, Europe and North Africa.  (Not a few of
+those who are fascinated by, and satisfied with, the statistical aspect of
+distribution still have a strong dislike to the use of "bridges" if these
+lead over deep seas, and they get over present discontinuous occurrences by
+a former "universal or sub-universal distribution" of their groups.  This
+is indeed an easy method of cutting the knot, but in reality they shunt the
+question only a stage or two back, never troubling to explain how their
+groups managed to attain to that sub-universal range; or do they still
+suppose that the whole world was originally one paradise where everything
+lived side by side, until sin and strife and glacial epochs left nothing
+but scattered survivors?
+
+The permanence of the great ocean-basins had become a dogma since it was
+found that a universal elevation of the land to the extent of 100 fathoms
+would produce but little changes, and when it was shown that even the 1000
+fathom-line followed the great masses of land rather closely, and still
+leaving the great basins (although transgression of the sea to the same
+extent would change the map of the world beyond recognition), by general
+consent one mile was allowed as the utmost speculative limit of subsidence.
+Naturally two or three miles, the average depth of the oceans, seems
+enormous, and yet such a difference in level is as nothing in comparison
+with the size of the Earth.  On a clay model globe ten feet in diameter an
+ocean bed three miles deep would scarcely be detected, and the highest
+mountains would be smaller than the unavoidable grains in the glazed
+surface of our model.  There are but few countries which have not be
+submerged at some time or other.)
+
+CONNECTION OF SOUTH EASTERN ASIA WITH AUSTRALIA.  Neumayr's Sino-Australian
+continent during mid-Mesozoic times was probably a much changing
+Archipelago, with final separations subsequent to the Cretaceous period. 
+Henceforth Australasia was left to its own fate, but for a possible
+connection with the antarctic continent.
+
+AFRICA, MADAGASCAR, INDIA.  The "Lemuria" of Sclater and Haeckel cannot
+have been more than a broad bridge in Jurassic times; whether it was ever
+available for the Lemurs themselves must depend upon the time of its
+duration, the more recent the better, but it is difficult to show that it
+lasted into the Miocene.
+
+AFRICA AND SOUTH AMERICA.  Since the opposite coasts show an entire absence
+of marine fossils and deposits during the Mesozoic period, whilst further
+north and south such are known to exist and are mostly identical on either
+side, Neumayr suggested the existence of a great Afro-Son American mass of
+land during the Jurassic epoch.  Such land is almost a necessity and is
+supported by many facts; it would easily explain the distribution of
+numerous groups of terrestrial creatures.  Moreover to the north of this
+hypothetical land, somewhere across from the Antilles and Guiana to North
+Africa and South Western Europe, existed an almost identical fauna of
+Corals and Molluscs, indicating either a coast-line or a series of islands
+interrupted by shallow seas, just as one would expect if, and when, a
+Brazil-Ethiopian mass of land were breaking up.  Lastly from Central
+America to the Mediterranean stretches one of the Tertiary tectonic lines
+of the geologists.  Here also the great question is how long this continent
+lasted.  Apparently the South Atlantic began to encroach from the south so
+that by the later Cretaceous epoch the land was reduced to a comparatively
+narrow Brazil-West Africa, remnants of which persisted certainly into the
+early Tertiary, until the South Atlantic joined across the equator with the
+Atlantic portion of the "Thetys," leaving what remained of South America
+isolated from the rest of the world.
+
+ANTARCTIC CONNECTIONS.  Patagonia and Argentina seem to have joined
+Antartica during the Cretaceous epoch, and this South Georgian bridge had
+broken down again by mid-Tertiary times when South America became
+consolidated.  The Antarctic continent, presuming that it existed, seems
+also to have been joined, by way of Tasmania, with Australia, also during
+the Cretaceous epoch, and it is assumed that the great Australia-Antarctic-
+Patagonian land was severed first to the south of Tasmania and then at the
+South Georgian bridge.  No connection, and this is important, is indicated
+between Antarctica and either Africa or Madagascar.
+
+So far we have followed what may be called the vicissitudes of the great
+Permo-Carboniferous Gondwana land in its fullest imaginary extent, an
+enormous equatorial and south temperate belt from South America to Africa,
+South India and Australia, which seems to have provided the foundation of
+the present Southern continents, two of which temporarily joined
+Antarctica, of which however we know nothing except that it exists now.
+
+Let us next consider the Arctic and periarctic lands.  Unfortunately very
+little is known about the region within the arctic circle.  If it was all
+land, or more likely great changing archipelagoes, faunistic exchange
+between North America, Europe and Siberia would present no difficulties,
+but there is one connection which engages much attention, namely a land
+where now lies the North temperate and Northern part of the Atlantic ocean. 
+How far south did it ever extend and what is the latest date of a direct
+practicable communication, say from North Western Europe to Greenland? 
+Connections, perhaps often interrupted, e.g. between Greenland and
+Labrador, at another time between Greenland and Scandinavia, seem to have
+existed at least since the Permo-Carboniferous epoch.  If they existed also
+in late Cretaceous and in Tertiary times, they would of course easily
+explain exchanges which we know to have repeatedly taken place between
+America and Europe, but they are not proved thereby, since most of these
+exchanges can almost as easily have occurred across the polar regions, and
+others still more easily by repeated junction of Siberia with Alaska.
+
+Let us now describe a hypothetical case based on the supposition of
+connecting bridges.  Not to work in a circle, we select an important group
+which has not served as a basis for the reconstruction of bridges; and it
+must be a group which we feel justified in assuming to be old enough to
+have availed itself of ancient land-connections.
+
+The occurrence of one species of Peripatus in the whole of Australia,
+Tasmania and New Zealand (the latter being joined to Australia by way of
+New Britain in Cretaceous times but not later) puts the genus back into
+this epoch, no unsatisfactory assumption to the morphologist.  The apparent
+absence of Peripatus in Madagascar indicates that it did not come from the
+east into Africa, that it was neither Afro-Indian, nor Afro-Australian; nor
+can it have started in South America.  We therefore assume as its creative
+centre Australia or Malaya in the Cretaceous epoch, whence its occurrence
+in Sumatra, Malay Peninsula, New Britain, New Zealand and Australia is
+easily explained.  Then extension across Antarctica to Patagonia and Chile,
+whence it could spread into the rest of South America as this became
+consolidated in early Tertiary times.  For getting to the Antilles and into
+Mexico it would have to wait until the Miocene, but long before that time
+it could arrive in Africa, there surviving as a Congolese and a Cape
+species.  This story is unsupported by a single fossil.  Peripatus may have
+been "sub-universal" all over greater Gondwana land in Carboniferous times,
+and then its absence from Madagascar would be difficult to explain, but the
+migrations suggested above amount to little considering that the distance
+from Tasmania to South America could be covered in far less time than that
+represented by the whole of the Eocene epoch alone.
+
+There is yet another field, essentially the domain of geographical
+distribution, the cultivation of which promises fair to throw much light
+upon Nature's way of making species.  This is the study of the organisms
+with regard to their environment.  Instead of revealing pedigrees or of
+showing how and when the creatures got to a certain locality, it
+investigates how they behaved to meet the ever changing conditions of their
+habitats.  There is a facies, characteristic of, and often peculiar to, the
+fauna of tropical moist forests, another of deserts, of high mountains, of
+underground life and so forth; these same facies are stamped upon whole
+associations of animals and plants, although these may be--and in widely
+separated countries generally are--drawn from totally different families of
+their respective orders.  It does not go to the root of the matter to say
+that these facies have been brought about by the extermination of all the
+others which did not happen to fit into their particular environment.  One
+might almost say that tropical moist forests must have arboreal frogs and
+that these are made out of whatever suitable material happened to be
+available; in Australia and South America Hylidae, in Africa Ranidae, since
+there Hylas are absent.  The deserts must have lizards capable of standing
+the glare, the great changes of temperature, of running over or burrowing
+into the loose sand.  When as in America Iguanids are available, some of
+these are thus modified, while in Africa and Asia the Agamids are drawn
+upon.  Both in the Damara and in the Transcaspian deserts, a Gecko has been
+turned into a runner upon sand!
+
+We cannot assume that at various epochs deserts, and at others moist
+forests were continuous all over the world.  The different facies and
+associations were developed at various times and places.  Are we to suppose
+that, wherever tropical forests came into existence, amongst the stock of
+humivagous lizards were always some which presented those nascent
+variations which made them keep step with the similarly nascent forests,
+the overwhelming rest being eliminated?  This principle would imply that
+the same stratum of lizards always had variations ready to fit any changed
+environment, forests and deserts, rocks and swamps.  The study of Ecology
+indicates a different procedure, a great, almost boundless plasticity of
+the organism, not in the sense of an exuberant moulding force, but of a
+readiness to be moulded, and of this the "variations" are the visible
+outcome.  In most cases identical facies are produced by heterogeneous
+convergences and these may seem to be but superficial, affecting only what
+some authors are pleased to call the physiological characters; but
+environment presumably affects first those parts by which the organism
+comes into contact with it most directly, and if the internal structures
+remain unchanged, it is not because these are less easily modified but
+because they are not directly affected.  When they are affected, they too
+change deeply enough.
+
+That the plasticity should react so quickly--indeed this very quickness
+seems to have initiated our mistaking the variations called forth for
+something performed--and to the point, is itself the outcome of the long
+training which protoplasm has undergone since its creation.
+
+In Nature's workshop he does not succeed who has ready an arsenal of tools
+for every conceivable emergency, but he who can make a tool at the spur of
+the moment.  The ordeal of the practical test is Charles Darwin's glorious
+conception of Natural Selection.
+
+
+XVIII.  DARWIN AND GEOLOGY.
+
+By J.W. JUDD, C.B., LL.D., F.R.S.
+
+(Mr Francis Darwin has related how his father occasionally came up from
+Down to spend a few days with his brother Erasmus in London, and, after his
+brother's death, with his daughter, Mrs Litchfield.  On these occasions, it
+was his habit to arrange meetings with Huxley, to talk over zoological
+questions, with Hooker, to discuss botanical problems, and with Lyell to
+hold conversations on geology.  After the death of Lyell, Darwin, knowing
+my close intimacy with his friend during his later years, used to ask me to
+meet him when he came to town, and "talk geology."  The "talks" took place
+sometimes at Jermyn Street Museum, at other times in the Royal College of
+Science, South Kensington; but more frequently, after having lunch with
+him, at his brother's or his daughter's house.  On several occasions,
+however, I had the pleasure of visiting him at Down.  In the postscript of
+a letter (of April 15, 1880) arranging one of these visits, he writes: 
+"Since poor, dear Lyell's death, I rarely have the pleasure of geological
+talk with anyone.")
+
+In one of the very interesting conversations which I had with Charles
+Darwin during the last seven years of his life, he asked me in a very
+pointed manner if I were able to recall the circumstances, accidental or
+otherwise, which had led me to devote myself to geological studies.  He
+informed me that he was making similar inquiries of other friends, and I
+gathered from what he said that he contemplated at that time a study of the
+causes producing SCIENTIFIC BIAS in individual minds.  I have no means of
+knowing how far this project ever assumed anything like concrete form, but
+certain it is that Darwin himself often indulged in the processes of mental
+introspection and analysis; and he has thus fortunately left us--in his
+fragments of autobiography and in his correspondence--the materials from
+which may be reconstructed a fairly complete history of his own mental
+development.
+
+There are two perfectly distinct inquiries which we have to undertake in
+connection with the development of Darwin's ideas on the subject of
+evolution:
+
+FIRST.  How, when, and under what conditions was Darwin led to a conviction
+that species were not immutable, but were derived from pre-existing forms?
+
+SECONDLY.  By what lines of reasoning and research was he brought to regard
+"natural selection" as a vera causa in the process of evolution?
+
+It is the first of these inquiries which specially interests the geologist;
+though geology undoubtedly played a part--and by no means an insignificant
+part--in respect to the second inquiry.
+
+When, indeed, the history comes to be written of that great revolution of
+thought in the nineteenth century, by which the doctrine of evolution, from
+being the dream of poets and visionaries, gradually grew to be the accepted
+creed of naturalists, the paramount influence exerted by the infant science
+of geology--and especially that resulting from the publication of Lyell's
+epoch-making work, the "Principles of Geology"--cannot fail to be regarded
+as one of the leading factors.  Herbert Spencer in his "Autobiography"
+bears testimony to the effect produced on his mind by the recently
+published "Principles", when, at the age of twenty, he had already begun to
+speculate on the subject of evolution (Herbert Spencer's "Autobiography",
+London, 1904, Vol. I. pages 175-177.); and Alfred Russel Wallace is
+scarcely less emphatic concerning the part played by Lyell's teaching in
+his scientific education.  (See "My Life; a record of Events and Opinions",
+London, 1905, Vol. I. page 355, etc.  Also his review of Lyell's
+"Principles" in "Quarterly Review" (Vol. 126), 1869, pages 359-394.  See
+also "The Darwin-Wallace Celebration by the Linnean Society" (1909), page
+118.)  Huxley wrote in 1887 "I owe more than I can tell to the careful
+study of the "Principles of Geology" in my young days."  ("Science and
+Pseudo Science"; "Collected Essays", London, 1902, Vol. V. page 101.)  As
+for Charles Darwin, he never tired--either in his published writings, his
+private correspondence or his most intimate conversations--of ascribing the
+awakening of his enthusiasm and the direction of his energies towards the
+elucidation of the problem of development to the "Principles of Geology"
+and the personal influence of its author.  Huxley has well expressed what
+the author of the "Origin of Species" so constantly insisted upon, in the
+statements "Darwin's greatest work is the outcome of the unflinching
+application to Biology of the leading idea and the method applied in the
+"Principles" to Geology ("Proc. Roy. Soc." Vol. XLIV. (1888), page viii.;
+"Collected Essays" II. page 268, 1902.), and "Lyell, for others, as for
+myself, was the chief agent in smoothing the road for Darwin."  ("Life and
+Letters of Charles Darwin" II. page 190.)
+
+We propose therefore to consider, first, what Darwin owed to geology and
+its cultivators, and in the second place how he was able in the end so
+fully to pay a great debt which he never failed to acknowledge.  Thanks to
+the invaluable materials contained in the "Life and Letters of Charles
+Darwin" (3 vols.) published by Mr Francis Darwin in 1887; and to "More
+Letters of Charles Darwin" (2 vols.) issued by the same author, in
+conjunction with Professor A.C. Seward, in 1903, we are permitted to follow
+the various movements in Darwin's mind, and are able to record the story
+almost entirely in his own words.  (The first of these works is indicated
+in the following pages by the letters "L.L."; the second by "M.L.")
+
+From the point of view of the geologist, Darwin's life naturally divides
+itself into four periods.  In the first, covering twenty-two years, various
+influences were at work militating, now for and now against, his adoption
+of a geological career; in the second period--the five memorable years of
+the voyage of the "Beagle"--the ardent sportsman with some natural-history
+tastes, gradually became the most enthusiastic and enlightened of
+geologists; in the third period, lasting ten years, the valuable geological
+recruit devoted nearly all his energies and time to geological study and
+discussion and to preparing for publication the numerous observations made
+by him during the voyage; the fourth period, which covers the latter half
+of his life, found Darwin gradually drawn more and more from geological to
+biological studies, though always retaining the deepest interest in the
+progress and fortunes of his "old love."  But geologists gladly recognise
+the fact that Darwin immeasurably better served their science by this
+biological work, than he could possibly have done by confining himself to
+purely geological questions.
+
+From his earliest childhood, Darwin was a collector, though up to the time
+when, at eight years of age, he went to a preparatory school, seals, franks
+and similar trifles appear to have been the only objects of his quest.  But
+a stone, which one of his schoolfellows at that time gave to him, seems to
+have attracted his attention and set him seeking for pebbles and minerals;
+as the result of this newly acquired taste, he says (writing in 1838) "I
+distinctly recollect the desire I had of being able to know something about
+every pebble in front of the hall door--it was my earliest and only
+geological aspiration at that time."  ("M.L." I. page 3.)  He further
+suspects that while at Mr Case's school "I do not remember any mental
+pursuits except those of collecting stones," etc..."I was born a
+naturalist."  ("M.L." I. page 4.)
+
+The court-yard in front of the hall door at the Mount House, Darwin's
+birthplace and the home of his childhood, is surrounded by beds or
+rockeries on which lie a number of pebbles.  Some of these pebbles (in
+quite recent times as I am informed) have been collected to form a
+"cobbled" space in front of the gate in the outer wall, which fronts the
+hall door; and a similar "cobbled area," there is reason to believe, may
+have existed in Darwin's childhood before the door itself.  The pebbles,
+which were obtained from a neighbouring gravel-pit, being derived from the
+glacial drift, exhibit very striking differences in colour and form.  It
+was probably this circumstance which awakened in the child his love of
+observation and speculation.  It is certainly remarkable that "aspirations"
+of the kind should have arisen in the mind of a child of 9 or 10!
+
+When he went to Shrewsbury School, he relates "I continued collecting
+minerals with much zeal, but quite unscientifically,--all that I cared
+about was a new-NAMED mineral, and I hardly attempted to classify them." 
+("L.L." I. page 34.)
+
+There has stood from very early times in Darwin's native town of
+Shrewsbury, a very notable boulder which has probably marked a boundary and
+is known as the "Bell-stone"--giving its name to a house and street. 
+Darwin tells us in his "Autobiography" that while he was at Shrewsbury
+School at the age of 13 or 14 "an old Mr Cotton in Shropshire, who knew a
+good deal about rocks" pointed out to me "...the 'bell-stone'; he told me
+that there was no rock of the same kind nearer than Cumberland or Scotland,
+and he solemnly assured me that the world would come to an end before
+anyone would be able to explain how this stone came where it now lay"! 
+Darwin adds "This produced a deep impression on me, and I meditated over
+this wonderful stone."  ("L.L." I. page 41.)
+
+The "bell-stone" has now, owing to the necessities of building, been
+removed a short distance from its original site, and is carefully preserved
+within the walls of a bank.  It is a block of irregular shape 3 feet long
+and 2 feet wide, and about 1 foot thick, weighing probably not less than
+one-third of a ton.  By the courtesy of the directors of the National
+Provincial Bank of England, I have been able to make a minute examination
+of it, and Professors Bonney and Watts, with Mr Harker and Mr Fearnsides
+have given me their valuable assistance.  The rock is a much altered
+andesite and was probably derived from the Arenig district in North Wales,
+or possibly from a point nearer the Welsh Border.  (I am greatly indebted
+to the Managers of the Bank at Shrewsbury for kind assistance in the
+examination of this interesting memorial:  and Mr H.T. Beddoes, the Curator
+of the Shrewsbury Museum, has given me some archaeological information
+concerning the stone.  Mr Richard Cotton was a good local naturalist, a
+Fellow both of the Geological and Linnean Societies; and to the officers of
+these societies I am indebted for information concerning him.  He died in
+1839, and although he does not appear to have published any scientific
+papers, he did far more for science by influencing the career of the school
+boy!"  It was of course brought to where Shrewsbury now stands by the
+agency of a glacier--as Darwin afterwards learnt.
+
+We can well believe from the perusal of these reminiscences that, at this
+time, Darwin's mind was, as he himself says, "prepared for a philosophical
+treatment of the subject" of Geology.  ("L.L." I. page 41.)  When at the
+age of 16, however, he was entered as a medical student at Edinburgh
+University, he not only did not get any encouragement of his scientific
+tastes, but was positively repelled by the ordinary instruction given
+there.  Dr Hope's lectures on Chemistry, it is true, interested the boy,
+who with his brother Erasmus had made a laboratory in the toolhouse, and
+was nicknamed "Gas" by his schoolfellows, while undergoing solemn and
+public reprimand from Dr Butler at Shrewsbury School for thus wasting his
+time.  ("L.L." I. page 35.)  But most of the other Edinburgh lectures were
+"intolerably dull," "as dull as the professors" themselves, "something
+fearful to remember."  In after life the memory of these lectures was like
+a nightmare to him.  He speaks in 1840 of Jameson's lectures as something
+"I...for my sins experienced!"  ("L.L." I. page 340.)  Darwin especially
+signalises these lectures on Geology and Zoology, which he attended in his
+second year, as being worst of all "incredibly dull.  The sole effect they
+produced on me was the determination never so long as I lived to read a
+book on Geology, or in any way to study the science!"  ("L.L." I. page 41.)
+
+The misfortune was that Edinburgh at that time had become the cockpit in
+which the barren conflict between "Neptunism" and Plutonism" was being
+waged with blind fury and theological bitterness.  Jameson and his pupils,
+on the one hand, and the friends and disciples of Hutton, on the other,
+went to the wildest extremes in opposing each other's peculiar tenets. 
+Darwin tells us that he actually heard Jameson "in a field lecture at
+Salisbury Craigs, discoursing on a trap-dyke, with amygdaloidal margins and
+the strata indurated on each side, with volcanic rocks all around us, say
+that it was a fissure filled with sediment from above, adding with a sneer
+that there were men who maintained that it had been injected from beneath
+in a molten condition."  ("L.L." I. pages 41-42.)  "When I think of this
+lecture," added Darwin, "I do not wonder that I determined never to attend
+to Geology."  (This was written in 1876 and Darwin had in the summer of
+1839 revisited and carefully studied the locality ("L.L." I. page 290.)  It
+is probable that most of Jameson's teaching was of the same controversial
+and unilluminating character as this field-lecture at Salisbury Craigs.
+
+There can be no doubt that, while at Edinburgh, Darwin must have become
+acquainted with the doctrines of the Huttonian School.  Though so young, he
+mixed freely with the scientific society of the city, Macgillivray, Grant,
+Leonard Horner, Coldstream, Ainsworth and others being among his
+acquaintances, while he attended and even read papers at the local
+scientific societies.  It is to be feared, however, that what Darwin would
+hear most of, as characteristic of the Huttonian teaching, would be
+assertions that chalk-flints were intrusions of molten silica, that fossil
+wood and other petrifactions had been impregnated with fused materials,
+that heat--but never water--was always the agent by which the induration
+and crystallisation of rock-materials (even siliceous conglomerate,
+limestone and rock-salt) had been effected!  These extravagant "anti-
+Wernerian" views the young student might well regard as not one whit less
+absurd and repellant than the doctrine of the "aqueous precipitation" of
+basalt.  There is no evidence that Darwin, even if he ever heard of them,
+was in any way impressed, in his early career, by the suggestive passages
+in Hutton and Playfair, to which Lyell afterwards called attention, and
+which foreshadowed the main principles of Uniformitarianism.
+
+As a matter of fact, I believe that the influence of Hutton and Playfair in
+the development of a philosophical theory of geology has been very greatly
+exaggerated by later writers on the subject.  Just as Wells and Matthew
+anticipated the views of Darwin on Natural Selection, but without producing
+any real influence on the course of biological thought, so Hutton and
+Playfair adumbrated doctrines which only became the basis of vivifying
+theory in the hands of Lyell.  Alfred Russel Wallace has very justly
+remarked that when Lyell wrote the "Principles of Geology", "the doctrines
+of Hutton and Playfair, so much in advance of their age, seemed to be
+utterly forgotten."  ("Quarterly Review", Vol. CXXVI. (1869), page 363.) 
+In proof of this it is only necessary to point to the works of the great
+masters of English geology, who preceded Lyell, in which the works of
+Hutton and his followers are scarcely ever mentioned.  This is true even of
+the "Researches in Theoretical Geology" and the other works of the
+sagacious De la Beche.  (Of the strength and persistence of the prejudice
+felt against Lyell's views by his contemporaries, I had a striking
+illustration some little time after Lyell's death.  One of the old
+geologists who in the early years of the century had done really good work
+in connection with the Geological Society expressed a hope that I was not
+"one of those who had been carried away by poor Lyell's fads."  My surprise
+was indeed great when further conversation showed me that the whole of the
+"Principles" were included in the "fads"!)  Darwin himself possessed a copy
+of Playfair's "Illustrations of the Huttonian Theory", and occasionally
+quotes it; but I have met with only one reference to Hutton, and that a
+somewhat enigmatical one, in all Darwin's writings.  In a letter to Lyell
+in 1841, when his mind was much exercised concerning glacial questions, he
+says "What a grand new feature all this ice work is in Geology!  How old
+Hutton would have stared!"  ("M.L." II. page 149.)
+
+As a consequence of the influences brought to bear on his mind during his
+two years' residence in Edinburgh, Darwin, who had entered that University
+with strong geological aspirations, left it and proceeded to Cambridge with
+a pronounced distaste for the whole subject.  The result of this was that,
+during his career as an under-graduate, he neglected all the opportunities
+for geological study.  During that important period of life, when he was
+between eighteen and twenty years of age, Darwin spent his time in riding,
+shooting and beetle-hunting, pursuits which were undoubtedly an admirable
+preparation for his future work as an explorer; but in none of his letters
+of this period does he even mention geology.  He says, however, "I was so
+sickened with lectures at Edinburgh that I did not even attend Sedgwick's
+eloquent and interesting lectures."  ("L.L." I. page 48.)
+
+It was only after passing his examination, and when he went up to spend two
+extra terms at Cambridge, that geology again began to attract his
+attention.  The reading of Sir John Herschel's "Introduction to the Study
+of Natural Philosophy", and of Humboldt's "Personal Narrative", a copy of
+which last had been given to him by his good friend and mentor Henslow,
+roused his dormant enthusiasm for science, and awakened in his mind a
+passionate desire for travel.  And it was from Henslow, whom he had
+accompanied in his excursions, but without imbibing any marked taste, at
+that time, for botany, that the advice came to think of and to "begin the
+study of geology."  ("L.L." I. page 56.)  This was in 1831, and in the
+summer vacation of that year we find him back again at Shrewsbury "working
+like a tiger" at geology and endeavouring to make a map and section of
+Shropshire--work which he says was not "as easy as I expected."  ("L.L." I.
+page 189.)  No better field for geological studies could possibly be found
+than Darwin's native county.
+
+Writing to Henslow at this time, and referring to a form of the instrument
+devised by his friend, Darwin says:  "I am very glad to say I think the
+clinometer will answer admirably.  I put all the tables in my bedroom at
+every conceivable angle and direction.  I will venture to say that I have
+measured them as accurately as any geologist going could do."  But he adds: 
+"I have been working at so many things that I have not got on much with
+geology.  I suspect the first expedition I take, clinometer and hammer in
+hand, will send me back very little wiser and a good deal more puzzled than
+when I started."  ("L.L." I. page 189.)  Valuable aid was, however, at
+hand, for at this time Sedgwick, to whom Darwin had been introduced by the
+ever-helpful Henslow, was making one of his expeditions into Wales, and
+consented to accept the young student as his companion during the
+geological tour.  ("L.L." I. page 56.)  We find Darwin looking forward to
+this privilege with the keenest interest.  ("L.L." I. page 189.)
+
+When at the beginning of August (1831), Sedgwick arrived at his father's
+house in Shrewsbury, where he spent a night, Darwin began to receive his
+first and only instruction as a field-geologist.  The journey they took
+together led them through Llangollen, Conway, Bangor, and Capel Curig, at
+which latter place they parted after spending many hours in examining the
+rocks at Cwm Idwal with extreme care, seeking for fossils but without
+success.  Sedgwick's mode of instruction was admirable--he from time to
+time sent the pupil off on a line parallel to his own, "telling me to bring
+back specimens of the rocks and to mark the stratification on a map." 
+("L.L." I. page 57.)  On his return to Shrewsbury, Darwin wrote to Henslow,
+"My trip with Sedgwick answered most perfectly," ("L.L." I. page 195.), and
+in the following year he wrote again from South America to the same friend,
+"Tell Professor Sedgwick he does not know how much I am indebted to him for
+the Welsh expedition; it has given me an interest in Geology which I would
+not give up for any consideration.  I do not think I ever spent a more
+delightful three weeks than pounding the north-west mountains."  ("L.L." I.
+pages 237-8.)
+
+It would be a mistake, however, to suppose that at this time Darwin had
+acquired anything like the affection for geological study, which he
+afterwards developed.  After parting with Sedgwick, he walked in a straight
+line by compass and map across the mountains to Barmouth to visit a reading
+party there, but taking care to return to Shropshire before September 1st,
+in order to be ready for the shooting.  For as he candidly tells us, "I
+should have thought myself mad to give up the first days of partridge-
+shooting for geology or any other science!"  ("L.L." I. page 58.)
+
+Any regret we may be disposed to feel that Darwin did not use his
+opportunities at Edinburgh and Cambridge to obtain systematic and practical
+instruction in mineralogy and geology, will be mitigated, however, when we
+reflect on the danger which he would run of being indoctrinated with the
+crude "catastrophic" views of geology, which were at that time prevalent in
+all the centres of learning.
+
+Writing to Henslow in the summer of 1831, Darwin says "As yet I have only
+indulged in hypotheses, but they are such powerful ones that I suppose, if
+they were put into action but for one day, the world would come to an end."
+("L.L." I. page 189.)
+
+May we not read in this passage an indication that the self-taught
+geologist had, even at this early stage, begun to feel a distrust for the
+prevalent catastrophism, and that his mind was becoming a field in which
+the seeds which Lyell was afterwards to sow would "fall on good ground"?
+
+The second period of Darwin's geological career--the five years spent by
+him on board the "Beagle"--was the one in which by far the most important
+stage in his mental development was accomplished.  He left England a
+healthy, vigorous and enthusiastic collector; he returned five years later
+with unique experiences, the germs of great ideas, and a knowledge which
+placed him at once in the foremost ranks of the geologists of that day. 
+Huxley has well said that "Darwin found on board the "Beagle" that which
+neither the pedagogues of Shrewsbury, nor the professoriate of Edinburgh,
+nor the tutors of Cambridge had managed to give him."  ("Proc. Roy. Soc."
+Vol. XLIV. (1888), page IX.)  Darwin himself wrote, referring to the date
+at which the voyage was expected to begin:  "My second life will then
+commence, and it shall be as a birthday for the rest of my life."  ("L.L."
+I. page 214.); and looking back on the voyage after forty years, he wrote;
+"The voyage of the 'Beagle' has been by far the most important event in my
+life, and has determined my whole career;...I have always felt that I owe
+to the voyage the first real training or education of my mind; I was led to
+attend closely to several branches of natural history, and thus my powers
+of observation were improved, though they were always fairly developed." 
+("L.L." I. page 61.)
+
+Referring to these general studies in natural history, however, Darwin adds
+a very significant remark:  "The investigation of the geology of the places
+visited was far more important, as reasoning here comes into play.  On
+first examining a new district nothing can appear more hopeless than the
+chaos of rocks; but by recording the stratification and nature of the rocks
+and fossils at many points, always reasoning and predicting what will be
+found elsewhere, light soon begins to dawn on the district, and the
+structure of the whole becomes more or less intelligible."  ("L.L." I. page
+62.)
+
+The famous voyage began amid doubts, discouragements and disappointments. 
+Fearful of heart-disease, sad at parting from home and friends, depressed
+by sea-sickness, the young explorer, after being twice driven back by
+baffling winds, reached the great object of his ambition, the island of
+Teneriffe, only to find that, owing to quarantine regulations, landing was
+out of the question.
+
+But soon this inauspicious opening of the voyage was forgotten.  Henslow
+had advised his pupil to take with him the first volume of Lyell's
+"Principles of Geology", then just published--but cautioned him (as nearly
+all the leaders in geological science at that day would certainly have
+done) "on no account to accept the views therein advocated."  ("L.L." I.
+page 73.)  It is probable that the days of waiting, discomfort and sea-
+sickness at the beginning of the voyage were relieved by the reading of
+this volume.  For he says that when he landed, three weeks after setting
+sail from Plymouth, in St Jago, the largest of the Cape de Verde Islands,
+the volume had already been "studied attentively; and the book was of the
+highest service to me in many ways..."  His first original geological work,
+he declares, "showed me clearly the wonderful superiority of Lyell's manner
+of treating geology, compared with that of any other author, whose works I
+had with me or ever afterwards read."  ("L.L." I. page 62.)
+
+At St Jago Darwin first experienced the joy of making new discoveries, and
+his delight was unbounded.  Writing to his father he says, "Geologising in
+a volcanic country is most delightful; besides the interest attached to
+itself, it leads you into most beautiful and retired spots."  ("L.L." I.
+page 228.)  To Henslow he wrote of St Jago:  "Here we spent three most
+delightful weeks...St Jago is singularly barren, and produces few plants or
+insects, so that my hammer was my usual companion, and in its company most
+delightful hours I spent."  "The geology was pre-eminently interesting, and
+I believe quite new; there are some facts on a large scale of upraised
+coast (which is an excellent epoch for all the volcanic rocks to date
+from), that would interest Mr Lyell."  ("L.L." I. page 235.)  After more
+than forty years the memory of this, his first geological work, seems as
+fresh as ever, and he wrote in 1876, "The geology of St Jago is very
+striking, yet simple:  a stream of lava formerly flowed over the bed of the
+sea, formed of triturated recent shells and corals, which it has baked into
+a hard white rock.  Since then the whole island has been upheaved.  But the
+line of white rock revealed to me a new and important fact, namely, that
+there had been afterwards subsidence round the craters, which had since
+been in action, and had poured forth lava."  ("L.L." I. page 65.)
+
+It was at this time, probably, that Darwin made his first attempt at
+drawing a sketch-map and section to illustrate the observations he had made
+(see his "Volcanic Islands", pages 1 and 9).  His first important
+geological discovery, that of the subsidence of strata around volcanic
+vents (which has since been confirmed by Mr Heaphy in New Zealand and other
+authors) awakened an intense enthusiasm, and he writes:  "It then first
+dawned on me that I might perhaps write a book on the geology of the
+various countries visited, and this made me thrill with delight.  That was
+a memorable hour to me, and how distinctly I can call to mind the low cliff
+of lava beneath which I rested, with the sun glaring hot, a few strange
+desert plants growing near, and with living corals in the tidal pools at my
+feet."  ("L.L." I. page 66.)
+
+But it was when the "Beagle", after touching at St Paul's rock and Tristan
+d'Acunha (for a sufficient time only to collect specimens), reached the
+shores of South America, that Darwin's real work began; and he was able,
+while the marine surveys were in progress, to make many extensive journeys
+on land.  His letters at this time show that geology had become his chief
+delight, and such exclamations as "Geology carries the day," "I find in
+Geology a never failing interest," etc. abound in his correspondence.
+
+Darwin's time was divided between the study of the great deposits of red
+mud--the Pampean formation--with its interesting fossil bones and shells
+affording proofs of slow and constant movements of the land, and the
+underlying masses of metamorphic and plutonic rocks.  Writing to Henslow in
+March, 1834, he says:  "I am quite charmed with Geology, but, like the wise
+animal between two bundles of hay, I do not know which to like best; the
+old crystalline groups of rocks, or the softer and fossiliferous beds. 
+When puzzling about stratification, etc., I feel inclined to cry 'a fig for
+your big oysters, and your bigger megatheriums.'  But then when digging out
+some fine bones, I wonder how any man can tire his arms with hammering
+granite."  ("L.L." I. page 249.)  We are told by Darwin that he loved to
+reason about and attempt to predict the nature of the rocks in each new
+district before he arrived at it.
+
+This love of guessing as to the geology of a district he was about to visit
+is amusingly expressed by him in a letter (of May, 1832) to his cousin and
+old college-friend, Fox.  After alluding to the beetles he had been
+collecting--a taste his friend had in common with himself--he writes of
+geology that "It is like the pleasure of gambling.  Speculating on first
+arriving, what the rocks may be, I often mentally cry out 3 to 1 tertiary
+against primitive; but the latter have hitherto won all the bets."  ("L.L."
+I. page 233.)
+
+Not the least important of the educational results of the voyage to Darwin
+was the acquirement by him of those habits of industry and method which
+enabled him in after life to accomplish so much--in spite of constant
+failures of health.  From the outset, he daily undertook and resolutely
+accomplished, in spite of sea-sickness and other distractions, four
+important tasks.  In the first place he regularly wrote up the pages of his
+Journal, in which, paying great attention to literary style and
+composition, he recorded only matters that would be of general interest,
+such as remarks on scenery and vegetation, on the peculiarities and habits
+of animals, and on the characters, avocations and political institutions of
+the various races of men with whom he was brought in contact.  It was the
+freshness of these observations that gave his "Narrative" so much charm. 
+Only in those cases in which his ideas had become fully crystallised, did
+he attempt to deal with scientific matters in this journal.  His second
+task was to write in voluminous note-books facts concerning animals and
+plants, collected on sea or land, which could not be well made out from
+specimens preserved in spirit; but he tells us that, owing to want of skill
+in dissecting and drawing, much of the time spent in this work was entirely
+thrown away, "a great pile of MS. which I made during the voyage has proved
+almost useless." ("L.L." I. page 62.)  Huxley confirmed this judgment on
+his biological work, declaring that "all his zeal and industry resulted,
+for the most part, in a vast accumulation of useless manuscript."  ("Proc.
+Roy. Soc." Vol. XLIV. (1888), page IX.)  Darwin's third task was of a very
+different character and of infinitely greater value.  It consisted in
+writing notes of his journeys on land--the notes being devoted to the
+geology of the districts visited by him.  These formed the basis, not only
+of a number of geological papers published on his return, but also of the
+three important volumes forming "The Geology of the voyage of the
+'Beagle'".  On July 24th, 1834, when little more than half of the voyage
+had been completed, Darwin wrote to Henslow, "My notes are becoming bulky. 
+I have about 600 small quarto pages full; about half of this is Geology." 
+("M.L." I. page 14.)  The last, and certainly not the least important of
+all his duties, consisted in numbering, cataloguing, and packing his
+specimens for despatch to Henslow, who had undertaken the care of them.  In
+his letters he often expresses the greatest solicitude lest the value of
+these specimens should be impaired by the removal of the numbers
+corresponding to his manuscript lists.  Science owes much to Henslow's
+patient care of the collections sent to him by Darwin.  The latter wrote in
+Henslow's biography, "During the five years' voyage, he regularly
+corresponded with me and guided my efforts; he received, opened, and took
+care of all the specimens sent home in many large boxes."  ("Life of
+Henslow", by L. Jenyns (Blomefield), London, 1862, page 53.)
+
+Darwin's geological specimens are now very appropriately lodged for the
+most part in the Sedgwick Museum, Cambridge, his original Catalogue with
+subsequent annotations being preserved with them.  From an examination of
+these catalogues and specimens we are able to form a fair notion of the
+work done by Darwin in his little cabin in the "Beagle", in the intervals
+between his land journeys.
+
+Besides writing up his notes, it is evident that he was able to accomplish
+a considerable amount of study of his specimens, before they were packed up
+for despatch to Henslow.  Besides hand-magnifiers and a microscope, Darwin
+had an equipment for blowpipe-analysis, a contact-goniometer and magnet;
+and these were in constant use by him.  His small library of reference (now
+included in the Collection of books placed by Mr F. Darwin in the Botany
+School at Cambridge ("Catalogue of the Library of Charles Darwin now in the
+Botany School, Cambridge".  Compiled by H.W. Rutherford; with an
+introduction by Francis Darwin.  Cambridge, 1908.)) appears to have been
+admirably selected, and in all probability contained (in addition to a good
+many works relating to South America) a fair number of excellent books of
+reference.  Among those relating to mineralogy, he possessed the manuals of
+Phillips, Alexander Brongniart, Beudant, von Kobell and Jameson:  all the
+"Cristallographie" of Brochant de Villers and, for blowpipe work, Dr
+Children's translation of the book of Berzelius on the subject.  In
+addition to these, he had Henry's "Experimental Chemistry" and Ure's
+"Dictionary" (of Chemistry).  A work, he evidently often employed, was P.
+Syme's book on "Werner's Nomenclature of Colours"; while, for Petrology, he
+used Macculloch's "Geological Classification of Rocks".  How diligently and
+well he employed his instruments and books is shown by the valuable
+observations recorded in the annotated Catalogues drawn up on board ship.
+
+These catalogues have on the right-hand pages numbers and descriptions of
+the specimens, and on the opposite pages notes on the specimens--the result
+of experiments made at the time and written in a very small hand.  Of the
+subsequently made pencil notes, I shall have to speak later.  (I am greatly
+indebted to my friend Mr A. Harker, F.R.S., for his assistance in examining
+these specimens and catalogues.  He has also arranged the specimens in the
+Sedgwick Museum, so as to make reference to them easy.  The specimens from
+Ascension and a few others are however in the Museum at Jermyn Street.)
+
+It is a question of great interest to determine the period and the occasion
+of Darwin's first awakening to the great problem of the transmutation of
+species.  He tells us himself that his grandfather's "Zoonomia" had been
+read by him "but without producing any effect," and that his friend Grant's
+rhapsodies on Lamarck and his views on evolution only gave rise to
+"astonishment."  ("L.L." I. page 38.)
+
+Huxley, who had probably never seen the privately printed volume of letters
+to Henslow, expressed the opinion that Darwin could not have perceived the
+important bearing of his discovery of bones in the Pampean Formation, until
+they had been studied in England, and their analogies pronounced upon by
+competent comparative anatomists.  And this seemed to be confirmed by
+Darwin's own entry in his pocket-book for 1837, "In July opened first
+notebook on Transmutation of Species.  Had been greatly struck from about
+the month of previous March on character of South American fossils..."
+("L.L." I. page 276.)
+
+The second volume of Lyell's "Principles of Geology" was published in
+January, 1832, and Darwin's copy (like that of the other two volumes, in a
+sadly dilapidated condition from constant use) has in it the inscription,
+"Charles Darwin, Monte Video.  Nov. 1832."  As everyone knows, Darwin in
+dedicating the second edition of his Journal of the Voyage to Lyell
+declared, "the chief part of whatever scientific merit this journal and the
+other works of the author may possess, has been derived from studying the
+well-known and admirable "Principles of Geology".
+
+In the first chapter of this second volume of the "Principles", Lyell
+insists on the importance of the species question to the geologist, but
+goes on to point out the difficulty of accepting the only serious attempt
+at a transmutation theory which had up to that time appeared--that of
+Lamarck.  In subsequent chapters he discusses the questions of the
+modification and variability of species, of hybridity, and of the
+geographical distribution of plants and animals.  He then gives vivid
+pictures of the struggle for existence, ever going on between various
+species, and of the causes which lead to their extinction--not by
+overwhelming catastrophes, but by the silent and almost unobserved action
+of natural causes.  This leads him to consider theories with regard to the
+introduction of new species, and, rejecting the fanciful notions of
+"centres or foci of creation," he argues strongly in favour of the view, as
+most reconcileable with observed facts, that "each species may have had its
+origin in a single pair, or individual, where an individual was sufficient,
+and species may have been created in succession at such times and in such
+places as to enable them to multiply and endure for an appointed period,
+and occupy an appointed space on the globe."  ("Principles of Geology",
+Vol. II. (1st edition 1832), page 124.  We now know, as has been so well
+pointed out by Huxley, that Lyell, as early as 1827, was prepared to accept
+the doctrine of the transmutation of species.  In that year he wrote to
+Mantell, "What changes species may really undergo!  How impossible will it
+be to distinguish and lay down a line, beyond which some of the so-called
+extinct species may have never passed into recent ones" (Lyell's "Life and
+Letters" Vol. I. page 168).  To Sir John Herschel in 1836, he wrote, "In
+regard to the origination of new species, I am very glad to find that you
+think it probable that it may be carried on through the intervention of
+intermediate causes.  I left this rather to be inferred, not thinking it
+worth while to offend a certain class of persons by embodying in words what
+would only be a speculation" (Ibid. page 467).  He expressed the same views
+to Whewell in 1837 (Ibid. Vol. II. page 5.), and to Sedgwick (Ibid. Vol.
+II. page 36) to whom he says, of "the theory, that the creation of new
+species is going on at the present day"--"I really entertain it," but "I
+have studiously avoided laying the doctrine down dogmatically as capable of
+proof" (see Huxley in "L.L." II. pages 190-195.))
+
+After pointing out how impossible it would be for a naturalist to prove
+that a newly DISCOVERED species was really newly CREATED (Mr F. Darwin has
+pointed out that his father (like Lyell) often used the term "Creation" in
+speaking of the origin of new species ("L.L." II. chapter 1.)), Lyell
+argued that no satisfactory evidence OF THE WAY in which these new forms
+were created, had as yet been discovered, but that he entertained the hope
+of a possible solution of the problem being found in the study of the
+geological record.
+
+It is not difficult, in reading these chapters of Lyell's great work, to
+realise what an effect they would have on the mind of Darwin, as new facts
+were collected and fresh observations concerning extinct and recent forms
+were made in his travels.  We are not surprised to find him writing home,
+"I am become a zealous disciple of Mr Lyell's views, as known in his
+admirable book.  Geologising in South America, I am tempted to carry parts
+to a greater extent even than he does."  ("L.L." I. page 263.)
+
+Lyell's anticipation that the study of the geological record might afford a
+clue to the discovery of how new species originate was remarkably
+fulfilled, within a few months, by Darwin's discovery of fossil bones in
+the red Pampean mud.
+
+It is very true that, as Huxley remarked, Darwin's knowledge of comparative
+anatomy must have been, at that time, slight; but that he recognised the
+remarkable resemblances between the extinct and existing mammals of South
+America is proved beyond all question by a passage in his letter to
+Henslow, written November 24th, 1832:  "I have been very lucky with fossil
+bones; I have fragments of at least six distinct animals...I found a large
+surface of osseous polygonal plates...Immediately I saw them I thought they
+must belong to an enormous armadillo, living species of which genus are so
+abundant here," and he goes on to say that he has "the lower jaw of some
+large animal which, from the molar teeth, I should think belonged to the
+Edentata."  ("M.L." I. pages 11, 12.  See "Extracts of Letters addressed to
+Prof. Henslow by C. Darwin" (1835), page 7.)
+
+Having found this important clue, Darwin followed it up with characteristic
+perseverance.  In his quest for more fossil bones he was indefatigable.  Mr
+Francis Darwin tells us, "I have often heard him speak of the despair with
+which he had to break off the projecting extremity of a huge, partly
+excavated bone, when the boat waiting for him would wait no longer." 
+("L.L." I. page 276 (footnote).)  Writing to Haeckel in 1864, Darwin says: 
+"I shall never forget my astonishment when I dug out a gigantic piece of
+armour, like that of the living armadillo."  (Haeckel, "History of
+Creation", Vol. I. page 134, London, 1876.)
+
+In a letter to Henslow in 1834 Darwin says:  "I have just got scent of some
+fossil bones...what they may be I do not know, but if gold or galloping
+will get them they shall be mine."  ("M.L." I. page 15.)
+
+Darwin also showed his sense of the importance of the discovery of these
+bones by his solicitude about their safe arrival and custody.  From the
+Falkland Isles (March, 1834), he writes to Henslow:  "I have been alarmed
+by your expression 'cleaning all the bones' as I am afraid the printed
+numbers will be lost:  the reason I am so anxious they should not be, is,
+that a part were found in a gravel with recent shells, but others in a very
+different bed.  Now with these latter there were bones of an Agouti, a
+genus of animals, I believe, peculiar to America, and it would be curious
+to prove that some one of the genus co-existed with the Megatherium:  such
+and many other points depend on the numbers being carefully preserved." 
+("Extracts from Letters etc.", pages 13-14.)  In the abstract of the notes
+read to the Geological Society in 1835, we read:  "In the gravel of
+Patagonia he (Darwin) also found many bones of the Megatherium and of five
+or six other species of quadrupeds, among which he has detected the bones
+of a species of Agouti.  He also met with several examples of the polygonal
+plates, etc."  ("Proc. Geol. Soc." Vol. II. pages 211-212.)
+
+Darwin's own recollections entirely bear out the conclusion that he fully
+recognised, WHILE IN SOUTH AMERICA, the wonderful significance of the
+resemblances between the extinct and recent mammalian faunas.  He wrote in
+his "Autobiography":  "During the voyage of the 'Beagle' I had been deeply
+impressed by discovering in the Pampean formation great fossil animals
+covered with armour like that on the existing armadillos."  ("L.L." I. page
+82.)
+
+The impression made on Darwin's mind by the discovery of these fossil
+bones, was doubtless deepened as, in his progress southward from Brazil to
+Patagonia, he found similar species of Edentate animals everywhere
+replacing one another among the living forms, while, whenever fossils
+occurred, they also were seen to belong to the same remarkable group of
+animals.  (While Darwin was making these observations in South America, a
+similar generalisation to that at which he arrived was being reached, quite
+independently and almost simultaneously, with respect to the fossil and
+recent mammals of Australia.  In the year 1831, Clift gave to Jameson a
+list of bones occurring in the caves and breccias of Australia, and in
+publishing this list the latter referred to the fact that the forms
+belonged to marsupials, similar to those of the existing Australian fauna. 
+But he also stated that, as a skull had been identified (doubtless
+erroneously) as having belonged to a hippopotamus, other mammals than
+marsupials must have spread over the island in late Tertiary times.  It is
+not necessary to point out that this paper was quite unknown to Darwin
+while in South America.  Lyell first noticed it in the third edition of his
+"Principles", which was published in May, 1834 (see "Edinb. New Phil.
+Journ." Vol. X. (1831), pages 394-6, and Lyell's "Principles" (3rd
+edition), Vol. III. page 421).  Darwin referred to this discovery in 1839
+(see his "Journal", page 210.)
+
+That the passage in Darwin's pocket-book for 1837 can only refer to an
+AWAKENING of Darwin's interest in the subject--probably resulting from a
+sight of the bones when they were being unpacked--I think there cannot be
+the smallest doubt; AND WE MAY THEREFORE CONFIDENTLY FIX UPON NOVEMBER,
+1832, AS THE DATE AT WHICH DARWIN COMMENCED THAT LONG SERIES OF
+OBSERVATIONS AND REASONINGS WHICH EVENTUALLY CULMINATED IN THE PREPARATION
+OF THE "ORIGIN OF SPECIES".  Equally certain is it, that it was his
+geological work that led Darwin into those paths of research which in the
+end conducted him to his great discoveries.  I quite agree with the view
+expressed by Mr F. Darwin and Professor Seward, that Darwin, like Lyell,
+"thought it 'almost useless' to try to prove the truth of evolution until
+the cause of change was discovered" ("M.L." I. page 38.), and that possibly
+he may at times have vacillated in his opinions, but I believe there is
+evidence that, from the date mentioned, the "species question" was always
+more or less present in Darwin's mind.  (Although we admit with Huxley that
+Darwin's training in comparative anatomy was very small, yet it may be
+remembered that he was a medical student for two years, and, if he hated
+the lectures, he enjoyed the society of naturalists.  He had with him in
+the little "Beagle" library a fair number of zoological books, including
+works on Osteology by Cuvier, Desmarest and Lesson, as well as two French
+Encyclopaedias of Natural History.  As a sportsman, he would obtain
+specimens of recent mammals in South America, and would thus have
+opportunities of studying their teeth and general anatomy.  Keen observer,
+as he undoubtedly was, we need not then be surprised that he was able to
+make out the resemblances between the recent and fossil forms.)
+
+It is clear that, as time went on, Darwin became more and more absorbed in
+his geological work.  One very significant fact was that the once ardent
+sportsman, when he found that shooting the necessary game and zoological
+specimens interfered with his work with the hammer, gave up his gun to his
+servant.  ("L.L." I. page 63.)  There is clear evidence that Darwin
+gradually became aware how futile were his attempts to add to zoological
+knowledge by dissection and drawing, while he felt ever increasing
+satisfaction with his geological work.
+
+The voyage fortunately extended to a much longer period (five years) than
+the two originally intended, but after being absent nearly three years,
+Darwin wrote to his sister in November, 1834, "Hurrah! hurrah! it is fixed
+that the 'Beagle' shall not go one mile south of Cape Tres Montes (about
+200 miles south of Chiloe), and from that point to Valparaiso will be
+finished in about five months.  We shall examine the Chonos Archipelago,
+entirely unknown, and the curious inland sea behind Chiloe.  For me it is
+glorious.  Cape Tres Montes is the most southern point where there is much
+geological interest, as there the modern beds end.  The Captain then talks
+of crossing the Pacific; but I think we shall persuade him to finish the
+coast of Peru, where the climate is delightful, the country hideously
+sterile, but abounding with the highest interest to the geologist...I have
+long been grieved and most sorry at the interminable length of the voyage
+(though I never would have quitted it)...I could not make up my mind to
+return.  I could not give up all the geological castles in the air I had
+been building up for the last two years."  ("L.L." I. pages 257-58.)
+
+In April, 1835, he wrote to another sister:  "I returned a week ago from my
+excursion across the Andes to Mendoza.  Since leaving England I have never
+made so successful a journey...how deeply I have enjoyed it; it was
+something more than enjoyment; I cannot express the delight which I felt at
+such a famous winding-up of all my geology in South America.  I literally
+could hardly sleep at nights for thinking over my day's work.  The scenery
+was so new, and so majestic; everything at an elevation of 12,000 feet
+bears so different an aspect from that in the lower country...To a
+geologist, also, there are such manifest proofs of excessive violence; the
+strata of the highest pinnacles are tossed about like the crust of a broken
+pie."  ("L.L." I. pages 259-60.)
+
+Darwin anticipated with intense pleasure his visit to the Galapagos
+Islands.  On July 12th, 1835, he wrote to Henslow:  "In a few days' time
+the "Beagle" will sail for the Galapagos Islands.  I look forward with joy
+and interest to this, both as being somewhat nearer to England and for the
+sake of having a good look at an active volcano.  Although we have seen
+lava in abundance, I have never yet beheld the crater."  ("M.L." I. page
+26.)  He could little anticipate, as he wrote these lines, the important
+aid in the solution of the "species question" that would ever after make
+his visit to the Galapagos Islands so memorable.  In 1832, as we have seen,
+the great discovery of the relations of living to extinct mammals in the
+same area had dawned upon his mind; in 1835 he was to find a second key for
+opening up the great mystery, by recognising the variations of similar
+types in adjoining islands among the Galapagos.
+
+The final chapter in the second volume of the "Principles" had aroused in
+Darwin's mind a desire to study coral-reefs, which was gratified during his
+voyage across the Pacific and Indian Oceans.  His theory on the subject was
+suggested about the end of 1834 or the beginning of 1835, as he himself
+tells us, before he had seen a coral-reef, and resulted from his work
+during two years in which he had "been incessantly attending to the effects
+on the shores of South America of the intermittent elevation of the land,
+together with denudation and the deposition of sediment."  ("L.L." I. page
+70.)
+
+On arriving at the Cape of Good Hope in July, 1836, Darwin was greatly
+gratified by hearing that Sedgwick had spoken to his father in high terms
+of praise concerning the work done by him in South America.  Referring to
+the news from home, when he reached Bahia once more, on the return voyage
+(August, 1836), he says:  "The desert, volcanic rocks, and wild sea of
+Ascension...suddenly wore a pleasing aspect, and I set to work with a good-
+will at my old work of Geology."  ("L.L." I. page 265.)  Writing fifty
+years later, he says:  "I clambered over the mountains of Ascension with a
+bounding step and made the volcanic rocks resound under my geological
+hammer!"  ("L.L." I. page 66.)
+
+That his determination was now fixed to devote his own labours to the task
+of working out the geological results of the voyage, and that he was
+prepared to leave to more practised hands the study of his biological
+collections, is clear from the letters he sent home at this time.  From St
+Helena he wrote to Henslow asking that he would propose him as a Fellow of
+the Geological Society; and his Certificate, in Henslow's handwriting, is
+dated September 8th, 1836, being signed from personal knowledge by Henslow
+and Sedgwick.  He was proposed on November 2nd and elected November 30th,
+being formally admitted to the Society by Lyell, who was then President, on
+January 4th, 1837, on which date he also read his first paper.  Darwin did
+not become a Fellow of the Linnean Society till eighteen years later (in
+1854).
+
+An estimate of the value and importance of Darwin's geological discoveries
+during the voyage of the "Beagle" can best be made when considering the
+various memoirs and books in which the author described them.  He was too
+cautious to allow himself to write his first impressions in his Journal,
+and wisely waited till he could study his specimens under better conditions
+and with help from others on his return.  The extracts published from his
+correspondence with Henslow and others, while he was still abroad, showed,
+nevertheless, how great was the mass of observation, how suggestive and
+pregnant with results were the reasonings of the young geologist.
+
+Two sets of these extracts from Darwin's letters to Henslow were printed
+while he was still abroad.  The first of these was the series of
+"Geological Notes made during a survey of the East and West Coasts of South
+America, in the years 1832, 1833, 1834 and 1835, with an account of a
+transverse section of the Cordilleras of the Andes between Valparaiso and
+Mendoza".  Professor Sedgwick, who read these notes to the Geological
+Society on November 18th, 1835, stated that "they were extracted from a
+series of letters (addressed to Professor Henslow), containing a great mass
+of information connected with almost every branch of natural history," and
+that he (Sedgwick) had made a selection of the remarks which he thought
+would be more especially interesting to the Geological Society.  An
+abstract of three pages was published in the "Proceedings of the Geological
+Society" (Vol. II. pages 210-12.), but so unknown was the author at this
+time that he was described as F. Darwin, Esq., of St John's College,
+Cambridge"!  Almost simultaneously (on November 16th, 1835) a second set of
+extracts from these letters--this time of a general character--were read to
+the Philosophical Society at Cambridge, and these excited so much interest
+that they were privately printed in pamphlet form for circulation among the
+members.
+
+Many expeditions and "scientific missions" have been despatched to various
+parts of the world since the return of the "Beagle" in 1836, but it is
+doubtful whether any, even the most richly endowed of them, has brought
+back such stores of new information and fresh discoveries as did that
+little "ten-gun brig"--certainly no cabin or laboratory was the birth-place
+of ideas of such fruitful character as was that narrow end of a chart-room,
+where the solitary naturalist could climb into his hammock and indulge in
+meditation.
+
+The third and most active portion of Darwin's career as a geologist was the
+period which followed his return to England at the end of 1836.  His
+immediate admission to the Geological Society, at the beginning of 1837,
+coincided with an important crisis in the history of geological science.
+
+The band of enthusiasts who nearly thirty years before had inaugurated the
+Geological Society--weary of the fruitless conflicts between "Neptunists"
+and "Plutonists"--had determined to eschew theory and confine their labours
+to the collection of facts, their publications to the careful record of
+observations.  Greenough, the actual founder of the Society, was an ardent
+Wernerian, and nearly all his fellow-workers had come, more or less
+directly, under the Wernerian teaching.  Macculloch alone gave valuable
+support to the Huttonian doctrines, so far as they related to the influence
+of igneous activity--but the most important portion of the now celebrated
+"Theory of the Earth"--that dealing with the competency of existing
+agencies to account for changes in past geological times--was ignored by
+all alike.  Macculloch's influence on the development of geology, which
+might have had far-reaching effects, was to a great extent neutralised by
+his peculiarities of mind and temper; and, after a stormy and troublous
+career, he retired from the society in 1832.  In all the writings of the
+great pioneers in English geology, Hutton and his splendid generalisation
+are scarcely ever referred to.  The great doctrines of Uniformitarianism,
+which he had foreshadowed, were completely ignored, and only his
+extravagances of "anti-Wernerianism" seem to have been remembered.
+
+When between 1830 and 1832, Lyell, taking up the almost forgotten ideas of
+Hutton, von Hoff and Prevost, published that bold challenge to the
+Catastrophists--the "Principles of Geology"--he was met with the strongest
+opposition, not only from the outside world, which was amused by his
+"absurdities" and shocked by his "impiety"--but not less from his fellow-
+workers and friends in the Geological Society.  For Lyell's numerous
+original observations, and his diligent collection of facts his
+contemporaries had nothing but admiration, and they cheerfully admitted him
+to the highest offices in the society, but they met his reasonings on
+geological theory with vehement opposition and his conclusions with
+coldness and contempt.
+
+There is, indeed, a very striking parallelism between the reception of the
+"Principles of Geology" by Lyell's contemporaries and the manner in which
+the "Origin of Species" was met a quarter of a century later, as is so
+vividly described by Huxley.  ("L.L." II. pages 179-204.)  Among Lyell's
+fellow-geologists, two only--G. Poulett Scrope and John Herschel (Both
+Lyell and Darwin fully realised the value of the support of these two
+friends.  Scrope in his appreciative reviews of the "Principles" justly
+pointed out what was the weakest point, the inadequate recognition of sub-
+aerial as compared with marine denudation.  Darwin also admitted that
+Scrope had to a great extent forestalled him in his theory of Foliation. 
+Herschel from the first insisted that the leading idea of the "Principles"
+must be applied to organic as well as to inorganic nature and must explain
+the appearance of new species (see Lyell's "Life and Letters", Vol. I. page
+467).  Darwin tells us that Herschel's "Introduction to the Study of
+Natural Philosophy" with Humboldt's "Personal Narrative" "stirred up in me
+a burning zeal" in his undergraduate days.  I once heard Lyell exclaim with
+fervour "If ever there was a heaven-born genius it was John Herschel!")--
+declared themselves from the first his strong supporters. Scrope in two
+luminous articles in the "Quarterly Review" did for Lyell what Huxley
+accomplished for Darwin in his famous review in the "Times"; but Scrope
+unfortunately was at that time immersed in the stormy sea of politics, and
+devoted his great powers of exposition to the preparation of fugitive
+pamphlets.  Herschel, like Scrope, was unable to support Lyell at the
+Geological Society, owing to his absence on the important astronomical
+mission to the Cape.
+
+It thus came about that, in the frequent conflicts of opinion within the
+walls of the Geological Society, Lyell had to bear the brunt of battle for
+Uniformitarianism quite alone, and it is to be feared that he found himself
+sadly overmatched when opposed by the eloquence of Sedgwick, the sarcasm of
+Buckland, and the dead weight of incredulity on the part of Greenough,
+Conybeare, Murchison and other members of the band of pioneer workers.  As
+time went on there is evidence that the opposition of De la Beche and
+Whewell somewhat relaxed; the brilliant "Paddy" Fitton (as his friends
+called him) was sometimes found in alliance with Lyell, but was
+characteristically apt to turn his weapon, as occasion served, on friend or
+foe alike; the amiable John Phillips "sat upon the fence."  Only when a new
+generation arose--including Jukes, Ramsay, Forbes and Hooker--did Lyell
+find his teachings received with anything like favour.
+
+We can well understand, then, how Lyell would welcome such a recruit as
+young Darwin--a man who had declared himself more Lyellian than Lyell, and
+who brought to his support facts and observations gleaned from so wide a
+field.
+
+The first meeting of Lyell and Darwin was characteristic of the two men. 
+Darwin at once explained to Lyell that, with respect to the origin of
+coral-reefs, he had arrived at views directly opposed to those published by
+"his master."  To give up his own theory, cost Lyell, as he told Herschel,
+a "pang at first," but he was at once convinced of the immeasurable
+superiority of Darwin's theory.  I have heard members of Lyell's family
+tell of the state of wild excitement and sustained enthusiasm, which lasted
+for days with Lyell after this interview, and his letters to Herschel,
+Whewell and others show his pleasure at the new light thrown upon the
+subject and his impatience to have the matter laid before the Geological
+Society.
+
+Writing forty years afterwards, Darwin, speaking of the time of the return
+of the "Beagle", says:  "I saw a great deal of Lyell.  One of his chief
+characteristics was his sympathy with the work of others, and I was as much
+astonished as delighted at the interest which he showed when, on my return
+to England, I explained to him my views on coral-reefs.  This encouraged me
+greatly, and his advice and example had much influence on me."  ("L.L." I.
+page 68.)  Darwin further states that he saw more of Lyell at this time
+than of any other scientific man, and at his request sent his first
+communication to the Geological Society.  ("L.L." I. page 67.)
+
+"Mr Lonsdale" (the able curator of the Geological Society), Darwin wrote to
+Henslow, "with whom I had much interesting conversation," "gave me a most
+cordial reception," and he adds, "If I was not much more inclined for
+geology than the other branches of Natural History, I am sure Mr Lyell's
+and Lonsdale's kindness ought to fix me.  You cannot conceive anything more
+thoroughly good-natured than the heart-and-soul manner in which he put
+himself in my place and thought what would be best to do."  ("L.L." I. page
+275.)
+
+Within a few days of Darwin's arrival in London we find Lyell writing to
+Owen as follows:
+
+"Mrs Lyell and I expect a few friends here on Saturday next, 29th
+(October), to an early tea party at eight o'clock, and it will give us
+great pleasure if you can join it.  Among others you will meet Mr Charles
+Darwin, whom I believe you have seen, just returned from South America,
+where he has laboured for zoologists as well as for hammer-bearers.  I have
+also asked your friend Broderip."  ("The Life of Richard Owen", London,
+1894, Vol. I. page 102.)  It would probably be on this occasion that the
+services of Owen were secured for the work on the fossil bones sent home by
+Darwin.
+
+On November 2nd, we find Lyell introducing Darwin as his guest at the
+Geological Society Club; on December 14th, Lyell and Stokes proposed Darwin
+as a member of the Club; between that date and May 3rd of the following
+year, when his election to the Club took place, he was several times dining
+as a guest.
+
+On January 4th, 1837, as we have already seen, Darwin was formally admitted
+to the Geological Society, and on the same evening he read his first paper
+(I have already pointed out that the notes read at the Geological Society
+on Nov. 18, 1835 were extracts made by Sedgwick from letters sent to
+Henslow, and not a paper sent home for publication by Darwin.) before the
+Society, "Observations of proofs of recent elevation on the coast of Chili,
+made during the Survey of H.M.S. "Beagle", commanded by Captain FitzRoy,
+R.N."  By C. Darwin, F.G.S.  This paper was preceded by one on the same
+subject by Mr A. Caldcleugh, and the reading of a letter and other
+communications from the Foreign Office also relating to the earthquakes in
+Chili.
+
+At the meeting of the Council of the Geological Society on February 1st,
+Darwin was nominated as a member of the new Council, and he was elected on
+February 17th.
+
+The meeting of the Geological Society on April 19th was devoted to the
+reading by Owen of his paper on Toxodon, perhaps the most remarkable of the
+fossil mammals found by Darwin in South America; and at the next meeting,
+on May 3rd, Darwin himself read "A Sketch of the Deposits containing
+extinct Mammalia in the neighbourhood of the Plata".  The next following
+meeting, on May 17th, was devoted to Darwin's Coral-reef paper, entitled
+"On certain areas of elevation and subsidence in the Pacific and Indian
+Oceans, as deduced from the study of Coral Formations".  Neither of these
+three early papers of Darwin were published in the Transactions of the
+Geological Society, but the minutes of the Council show that they were
+"withdrawn by the author by permission of the Council."
+
+Darwin's activity during this session led to some rather alarming effects
+upon his health, and he was induced to take a holiday in Staffordshire and
+the Isle of Wight.  He was not idle, however, for a remark of his uncle, Mr
+Wedgwood, led him to make those interesting observations on the work done
+by earthworms, that resulted in his preparing a short memoir on the
+subject, and this paper, "On the Formation of Mould", was read at the
+Society on November 1st, 1837, being the first of Darwin's papers published
+in full; it appeared in Vol. V. of the "Geological Transactions", pages
+505-510.)
+
+During this session, Darwin attended nearly all the Council meetings, and
+took such an active part in the work of the Society that it is not
+surprising to find that he was now requested to accept the position of
+Secretary.  After some hesitation, in which he urged his inexperience and
+want of knowledge of foreign languages, he consented to accept the
+appointment.  ("L.L." I. page 285.)
+
+At the anniversary meeting on February 16th, 1838, the Wollaston Medal was
+given to Owen in recognition of his services in describing the fossil
+mammals sent home by Darwin.  In his address, the President, Professor
+Whewell, dwelt at length on the great value of the papers which Darwin had
+laid before the Society during the preceding session.
+
+On March 7th, Darwin read before the Society the most important perhaps of
+all his geological papers, "On the Connexion of certain Volcanic Phenomena
+in South America, and on the Formation of Mountain-Chains and Volcanoes as
+the effect of Continental Elevations".  In this paper he boldly attacked
+the tenets of the Catastrophists.  It is evident that Darwin at this time,
+taking advantage of the temporary improvement in his health, was throwing
+himself into the breach of Uniformitarianism with the greatest ardour. 
+Lyell wrote to Sedgwick on April 21st, 1837, "Darwin is a glorious addition
+to any society of geologists, and is working hard and making way, both in
+his book and in our discussions."  ("The Life and Letters of the Reverend
+Adam Sedgwick", Vol. I. page 484, Cambridge, 1890.)
+
+We have unfortunately few records of the animated debates which took place
+at this time between the old and new schools of geologists.  I have often
+heard Lyell tell how Lockhart would bring down a party of friends from the
+Athenaeum Club to Somerset House on Geological nights, not, as he carefully
+explained, that "he cared for geology, but because he liked to while the
+fellows fight."  But it fortunately happens that a few days after this last
+of Darwin's great field-days, at the Geological Society, Lyell, in a
+friendly letter to his father-in-law, Leonard Horner, wrote a very lively
+account of the proceedings while his impressions were still fresh; and this
+gives us an excellent idea of the character of these discussions.
+
+Neither Sedgwick nor Buckland were present on this occasion, but we can
+imagine how they would have chastised their two "erring pupils"--more in
+sorrow than in anger--had they been there.  Greenough, too, was absent--
+possibly unwilling to countenance even by his presence such outrageous
+doctrines.
+
+Darwin, after describing the great earthquakes which he had experienced in
+South America, and the evidence of their connection with volcanic
+outbursts, proceeded to show that earthquakes originated in fractures,
+gradually formed in the earth's crust, and were accompanied by movements of
+the land on either side of the fracture.  In conclusion he boldly advanced
+the view "that continental elevations, and the action of volcanoes, are
+phenomena now in progress, caused by some great but slow change in the
+interior of the earth; and, therefore, that it might be anticipated, that
+the formation of mountain chains is likewise in progress:  and at a rate
+which may be judged of by either actions, but most clearly by the growth of
+volcanoes."  ("Proc. Geol. Soc." Vol. II. pages 654-60.)
+
+Lyell's account ("Life, Letters and Journals of Sir Charles Lyell, Bart.",
+edited by his sister-in-law, Mrs Lyell, Vol. II. pages 40, 41 (Letter to
+Leonard Horner, 1838), 2 vols.  London, 1881.) of the discussion was as
+follows:  "In support of my heretical notions," Darwin "opened upon De la
+Beche, Phillips and others his whole battery of the earthquakes and
+volcanoes of the Andes, and argued that spaces at least a thousand miles
+long were simultaneously subject to earthquakes and volcanic eruptions, and
+that the elevation of the Pampas, Patagonia, etc., all depended on a common
+cause; also that the greater the contortions of strata in a mountain chain,
+the smaller must have been each separate and individual movement of that
+long series which was necessary to upheave the chain.  Had they been more
+violent, he contended that the subterraneous fluid matter would have gushed
+out and overflowed, and the strata would have been blown up and
+annihilated.  (It is interesting to compare this with what Darwin wrote to
+Henslow seven years earlier.)  He therefore introduces a cooling of one
+small underground injection, and then the pumping in of other lava, or
+porphyry, or granite, into the previously consolidated and first-formed
+mass of igneous rock.  (Ideas somewhat similar to this suggestion have
+recently been revived by Dr See ("Proc. Am. Phil. Soc." Vol. XLVII. 1908,
+page 262.).)  When he had done his description of the reiterated strokes of
+his volcanic pump, De la Beche gave us a long oration about the
+impossibility of strata of the Alps, etc., remaining flexible for such a
+time as they must have done, if they were to be tilted, convoluted, or
+overturned by gradual small shoves.  He never, however, explained his
+theory of original flexibility, and therefore I am as unable as ever to
+comprehend why flexiblility is a quality so limited in time.
+
+"Phillips then got up and pronounced a panegyric upon the "Principles of
+Geology", and although he still differed, thought the actual cause doctrine
+had been so well put, that it had advanced the science and formed a date or
+era, and that for centuries the two opposite doctrines would divide
+geologists, some contending for greater pristine forces, others satisfied,
+like Lyell and Darwin, with the same intensity as nature now employs.
+
+"Fitton quizzed Phillips a little for the warmth of his eulogy, saying that
+he (Fitton) and others, who had Mr Lyell always with them, were in the
+habit of admiring and quarrelling with him every day, as one might do with
+a sister or cousin, whom one would only kiss and embrace fervently after a
+long absence.  This seemed to be Mr Phillips' case, coming up occasionally
+from the provinces.  Fitton then finished this drollery by charging me with
+not having done justice to Hutton, who he said was for gradual elevation.
+
+"I replied, that most of the critics had attacked me for overrating Hutton,
+and that Playfair understood him as I did.
+
+"Whewell concluded by considering Hopkins' mathematical calculations, to
+which Darwin had often referred.  He also said that we ought not to try and
+make out what Hutton would have taught and thought, if he had known the
+facts which we now know."
+
+It may be necessary to point out, in explanation of the above narrative,
+that while it was perfectly clear from Hutton's rather obscure and involved
+writings that he advocated slow and gradual change on the earth's surface,
+his frequent references to violent action and earthquakes led many--
+including Playfair, Lyell and Whewell--to believe that he held the changes
+going on in the earth's interior to be of a catastrophic nature.  Fitton,
+however, maintained that Hutton was consistently uniformitarian.  Before
+the idea of the actual "flowing" of solid bodies under intense pressure had
+been grasped by geologists, De la Beche, like Playfair before him,
+maintained that the bending and folding of rocks must have been effected
+before their complete consolidation.
+
+In concluding his account of this memorable discussion, Lyell adds:  "I was
+much struck with the different tone in which my gradual causes was treated
+by all, even including De la Beche, from that which they experienced in the
+same room four years ago, when Buckland, De la Beche(?), Sedgwick, Whewell,
+and some others treated them with as much ridicule as was consistent with
+politeness in my presence."
+
+This important paper was, in spite of its theoretical character, published
+in full in the "Transactions of the Geological Society" (Ser. 2, Vol. V.
+pages 601-630).  It did not however appear till 1840, and possibly some
+changes may have been made in it during the long interval between reading
+and printing.  During the year 1839, Darwin continued his regular
+attendance at the Council meetings, but there is no record of any
+discussions in which he may have taken part, and he contributed no papers
+himself to the Society.  At the beginning of 1840, he was re-elected for
+the third time as Secretary, but the results of failing health are
+indicated by the circumstance that, only at one meeting early in the
+session, was he able to attend the Council.  At the beginning of the next
+session (Feb. 1841) Bunbury succeeded him as Secretary, Darwin still
+remaining on the Council.  It may be regarded as a striking indication of
+the esteem in which he was held by his fellow geologists, that Darwin
+remained on the Council for 14 consecutive years down to 1849, though his
+attendances were in some years very few.  In 1843 and 1844 he was a Vice-
+president, but after his retirement at the beginning of 1850, he never
+again accepted re-nomination.  He continued, however, to contribute papers
+to the Society, as we shall see, down to the end of 1862.
+
+Although Darwin early became a member of the Geological Dining Club, it is
+to be feared that he scarcely found himself in a congenial atmosphere at
+those somewhat hilarious gatherings, where the hardy wielders of the hammer
+not only drank port--and plenty of it--but wound up their meal with a
+mixture of Scotch ale and soda water, a drink which, as reminiscent of the
+"field," was regarded as especially appropriate to geologists.  Even after
+the meetings, which followed the dinners, they reassembled for suppers, at
+which geological dainties, like "pterodactyle pie" figured in the bill of
+fare, and fines of bumpers were inflicted on those who talked the
+"ologies."
+
+After being present at a fair number of meetings in 1837 and 1838, Darwin's
+attendances at the Club fell off to two in 1839, and by 1841 he had ceased
+to be a member.  In a letter to Lyell on Dec. 2nd, 1841, Leonard Horner
+wrote that the day before "At the Council, I had the satisfaction of seeing
+Darwin again in his place and looking well.  He tried the last evening
+meeting, but found it too much, but I hope before the end of the season he
+will find himself equal to that also.  I hail Darwin's recovery as a vast
+gain to science."  Darwin's probably last attendance, this time as a guest,
+was in 1851, when Horner again wrote to Lyell, "Charles Darwin was at the
+Geological Society's Club yesterday, where he had not been for ten years--
+remarkably well, and grown quite stout."  ("Memoirs of Leonard Horner"
+(privately printed), Vol. II. pages 39 and 195.)
+
+It may be interesting to note that at the somewhat less lively dining Club-
+-the Philosophical--in the founding of which his friends Lyell and Hooker
+had taken so active a part, Darwin found himself more at home, and he was a
+frequent attendant--in spite of his residence being at Down--from 1853 to
+1864.  He even made contributions on scientific questions after these
+dinners.  In a letter to Hooker he states that he was deeply interested in
+the reforms of the Royal Society, which the Club was founded to promote. 
+He says also that he had arranged to come to town every Club day "and then
+my head, I think, will allow me on an average to go to every other meeting. 
+But it is grievous how often any change knocks me up."  ("L.L." II. pages
+42, 43.)
+
+Of the years 1837 and 1838 Darwin himself says they were "the most active
+ones which I ever spent, though I was occasionally unwell, and so lost some
+time...I also went a little into society."  ("L.L." I. pages 67, 68.)  But
+of the four years from 1839 to 1842 he has to confess sadly "I did less
+scientific work, though I worked as hard as I could, than during any other
+equal length of time in my life.  This was owing to frequently recurring
+unwellness, and to one long and serious illness."  ("L.L." I. page 69.)
+
+Darwin's work at the Geological Society did not by any means engage the
+whole of his energies, during the active years 1837 and 1838.  In June of
+the latter year, leaving town in somewhat bad health, he found himself at
+Edinburgh again, and engaged in examining the Salisbury Craigs, in a very
+different spirit to that excited by Jameson's discourse.  ("L.L." I. page
+290.)  Proceeding to the Highlands he then had eight days of hard work at
+the famous "Parallel Roads of Glen Roy", being favoured with glorious
+weather.
+
+He says of the writing of the paper on the subject--the only memoir
+contributed by Darwin to the Royal Society, to which he had been recently
+elected--that it was "one of the most difficult and instructive tasks I was
+ever engaged on."  The paper extends to 40 quarto pages and is illustrated
+by two plates.  Though it is full of the records of careful observation and
+acute reasoning, yet the theory of marine beaches which he propounded was,
+as he candidly admitted in after years ("M.L." II page 188.), altogether
+wrong.  The alternative lake-theory he found himself unable to accept at
+the time, for he could not understand how barriers could be formed at
+successive levels across the valleys; and until the following year, when
+the existence of great glaciers in the district was proved by the
+researches of Agassiz, Buckland and others, the difficulty appeared to him
+an insuperable one.  Although Darwin said of this paper in after years that
+it "was a great failure and I am ashamed of it"--yet he retained his
+interest in the question ever afterwards, and he says "my error has been a
+good lesson to me never to trust in science to the principle of exclusion."
+("M.L." II. pages 171-93.)
+
+Although Darwin had not realised in 1838 that large parts of the British
+Islands had been occupied by great glaciers, he had by no means failed
+while in South America to recognise the importance of ice-action.  His
+observations, as recorded in his Journal, on glaciers coming down to the
+sea-level, on the west coast of South America, in a latitude corresponding
+to a much lower one than that of the British Islands, profoundly interested
+geologists; and the same work contains many valuable notes on the boulders
+and unstratified beds in South America in which they were included.
+
+But in 1840 Agassiz read his startling paper on the evidence of the former
+existence of glaciers in the British Islands, and this was followed by
+Buckland's memoir on the same subject.  On April 14, 1841, Darwin
+contributed to the Geological Society his important paper "On the
+Distribution of Erratic Boulders and the Contemporaneous Unstratified
+Deposits of South America", a paper full of suggestiveness for those
+studying the glacial deposits of this country.  It was published in the
+"Transactions" in 1842.
+
+The description of traces of glacial action in North Wales, by Buckland,
+appears to have greatly excited the interest of Darwin.  With Sedgwick he
+had, in 1831, worked at the stratigraphy of that district, but neither of
+them had noticed the very interesting surface features.  ("L.L." I. page
+58.)  Darwin was able to make a journey to North Wales in June, 1842 (alas!
+it was his last effort in field-geology) and as a result he published his
+most able and convincing paper on the subject in the September number of
+the "Philosophical Magazine" for 1842.  Thus the mystery of the bell-stone
+was at last solved and Darwin, writing many years afterwards, said "I felt
+the keenest delight when I first read of the action of icebergs in
+transporting boulders, and I gloried in the progress of Geology."  ("L.L."
+I. page 41.)  To the "Geographical Journal" he had sent in 1839 a note "On
+a Rock seen on an Iceberg in 16 deg S. Latitude."  For the subject of ice-
+action, indeed, Darwin retained the greatest interest to the end of his
+life.  ("M.L." II. pages 148-71.)
+
+In 1846, Darwin read two papers to the Geological Society "On the dust
+which falls on vessels in the Atlantic, and On the Geology of the Falkland
+Islands"; in 1848 he contributed a note on the transport of boulders from
+lower to higher levels; and in 1862 another note on the thickness of the
+Pampean formation, as shown by recent borings at Buenos Ayres.  An account
+of the "British Fossil Lepadidae" read in 1850, was withdrawn by him.
+
+At the end of 1836 Darwin had settled himself in lodgings in Fitzwilliam
+Street, Cambridge, and devoted three months to the work of unpacking his
+specimens and studying his collection of rocks.  The pencilled notes on the
+Manuscript Catalogue in the Sedgwick Museum enable us to realise his mode
+of work, and the diligence with which it was carried on.  The letters M and
+H, indicate the assistance he received from time to time from Professor
+Miller, the crystallographer, and from his friend Henslow.  Miller not only
+measured many of the crystals submitted to him, but evidently taught Darwin
+to use the reflecting goniometer himself with considerable success.  The
+"book of measurements" in which the records were kept, appears to have been
+lost, but the pencilled notes in the catalogue show how thoroughly the work
+was done.  The letter R attached to some of the numbers in the catalogue
+evidently refers to the fact that they were submitted to Mr Trenham Reeks
+(who analysed some of his specimens) at the Geological Survey quarters in
+Craig's Court.  This was at a later date when Darwin was writing the
+"Volcanic Islands" and "South America".
+
+It was about the month of March, 1837, that Darwin completed this work upon
+his rocks, and also the unpacking and distribution of his fossil bones and
+other specimens.  We have seen that November, 1832, must certainly be
+regarded as the date when he FIRST realised the important fact that the
+fossil mammals of the Pampean formation were all closely related to the
+existing forms in South America; while October, 1835, was, as undoubtedly,
+the date when the study of the birds and other forms of life in the several
+islands of the Galapagos Islands gave him his SECOND impulse towards
+abandoning the prevalent view of the immutability of species.  When then in
+his pocket-book for 1837 Darwin wrote the often quoted passage:  "In July
+opened first note-book on Transmutation of Species.  Had been greatly
+struck from about the month of previous March on character of South
+American fossils, and species on Galapagos Archipelago.  These facts
+(especially latter), origin of all my views" ("L.L." I. page 276.), it is
+clear that he must refer, not to his first inception of the idea of
+evolution, but to the flood of recollections, the reawakening of his
+interest in the subject, which could not fail to result from the sight of
+his specimens and the reference to his notes.
+
+Except during the summer vacation, when he was visiting his father and
+uncle, and with the latter making his first observations upon the work of
+earthworms, Darwin was busy with his arrangements for the publication of
+the five volumes of the "Zoology of the 'Beagle'" and in getting the
+necessary financial aid from the government for the preparation of the
+plates.  He was at the same time preparing his "Journal" for publication. 
+During the years 1837 to 1843, Darwin worked intermittently on the volumes
+of Zoology, all of which he edited, while he wrote introductions to those
+by Owen and Waterhouse and supplied notes to the others.
+
+Although Darwin says of his Journal that the preparation of the book "was
+not hard work, as my MS. Journal had been written with care."  Yet from the
+time that he settled at 36, Great Marlborough Street in March, 1837, to the
+following November he was occupied with this book.  He tells us that the
+account of his scientific observations was added at this time.  The work
+was not published till March, 1839, when it appeared as the third volume of
+the "Narrative of the Surveying Voyages of H.M. Ships 'Adventure' and
+'Beagle' between the years 1826 and 1836".  The book was probably a long
+time in the press, for there are no less than 20 pages of addenda in small
+print.  Even in this, its first form, the work is remarkable for its
+freshness and charm, and excited a great amount of attention and interest. 
+In addition to matters treated of in greater detail in his other works,
+there are many geological notes of extreme value in this volume, such as
+his account of lightning tubes, of the organisms found in dust, and of the
+obsidian bombs of Australia.
+
+Having thus got out of hand a number of preliminary duties, Darwin was
+ready to set to work upon the three volumes which were designed by him to
+constitute "The Geology of the Voyage of the 'Beagle'".  The first of these
+was to be on "The Structure and Distribution of Coral-reefs".  He commenced
+the writing of the book on October 5, 1838, and the last proof was
+corrected on May 6, 1842.  Allowing for the frequent interruptions through
+illness, Darwin estimated that it cost him twenty months of hard work.
+
+Darwin has related how his theory of Coral-reefs which was begun in a more
+"deductive spirit" than any of his other work, for in 1834 or 1835 it "was
+thought out on the west coast of South America, before I had seen a true
+coral-reef."  ("L.L." I. page 70.)  The final chapter in Lyell's second
+volume of the "Principles" was devoted to the subject of Coral-reefs, and a
+theory was suggested to account for the peculiar phenomena of "atolls."
+Darwin at once saw the difficulty of accepting the view that the numerous
+and diverse atolls all represent submerged volcanic craters.  His own work
+had for two years been devoted to the evidence of land movements over great
+areas in South America, and thus he was led to announce his theory of
+subsidence to account for barrier and encircling reefs as well as atolls.
+
+Fortunately, during his voyage across the Pacific and Indian Oceans, in his
+visit to Australia and his twelve days' hard work at Keeling Island, he had
+opportunities for putting his theory to the test of observation.
+
+On his return to England, Darwin appears to have been greatly surprised at
+the amount of interest that his new theory excited.  Urged by Lyell, he
+read to the Geological Society a paper on the subject, as we have seen,
+with as little delay as possible, but this paper was "withdrawn by
+permission of the Council."  An abstract of three pages however appeared in
+the "Proceedings of the Geological Society".  (Vol. II. pages 552-554 (May
+31, 1837).)  A full account of the observations and the theory was given in
+the "Journal" (1839) in the 40 pages devoted to Keeling Island in
+particular and to Coral formations generally.  ("Journal (1st edition),
+pages 439-69.)
+
+It will be readily understood what an amount of labour the book on Coral
+reefs cost Darwin when we reflect on the number of charts, sailing
+directions, narratives of voyages and other works which, with the friendly
+assistance of the authorities at the Admiralty, he had to consult before he
+could draw up his sketch of the nature and distribution of the reefs, and
+this was necessary before the theory, in all its important bearings, could
+be clearly enunciated.  Very pleasing is it to read how Darwin, although
+arriving at a different conclusion to Lyell, shows, by quoting a very
+suggestive passage in the "Principles" (1st edition Vol. II. page 296.),
+how the latter only just missed the true solution.  This passage is cited,
+both in the "Journal" and the volume on Coral-reefs.  Lyell, as we have
+seen, received the new theory not merely ungrudgingly, but with the utmost
+enthusiasm.
+
+In 1849 Darwin was gratified by receiving the support of Dana, after his
+prolonged investigation in connection with the U.S. Exploring Expedition
+("M.L." II. pages 226-8.), and in 1874 he prepared a second edition of his
+book, in which some objections which had been raised to the theory were
+answered.  A third edition, edited by Professor Bonney, appeared in 1880,
+and a fourth (a reprint of the first edition, with introduction by myself)
+in 1890.
+
+Although Professor Semper, in his account of the Pelew Islands, had
+suggested difficulties in the acceptance of Darwin's theory, it was not
+till after the return of the "Challenger" expedition in 1875 that a rival
+theory was propounded, and somewhat heated discussions were raised as to
+the respective merits of the two theories.  While geologists have, nearly
+without exception, strongly supported Darwin's views, the notes of dissent
+have come almost entirely from zoologists.  At the height of the
+controversy unfounded charges of unfairness were made against Darwin's
+supporters and the authorities of the Geological Society, but this
+unpleasant subject has been disposed of, once for all, by Huxley.  ("Essays
+upon some Controverted Questions", London, 1892, pages 314-328 and 623-
+625.)
+
+Darwin's final and very characteristic utterance on the coral-reef
+controversy is found in a letter which he wrote to Professor Alexander
+Agassiz, May 5th, 1881:  less than a year before his death:  "If I am
+wrong, the sooner I am knocked on the head and annihilated so much the
+better.  It still seems to me a marvellous thing that there should not have
+been much, and long-continued, subsidence in the beds of the great oceans.
+I wish that some doubly rich millionaire would take it into his head to
+have borings made in some of the Pacific and Indian atolls, and bring home
+cores for slicing from a depth of 500 or 600 feet."  ("L.L." III. page
+184.)
+
+Though the "doubly rich millionaire" has not been forthcoming, the energy,
+in England, of Professor Sollas, and in New South Wales of Professor
+Anderson Stuart served to set on foot a project, which, aided at first by
+the British Association for the Advancement of Science, and afterwards
+taken up jointly by the Royal Society, the New South Wales Government, and
+the Admiralty, has led to the most definite and conclusive results.
+
+The Committee appointed by the Royal Society to carry out the undertaking
+included representatives of all the views that had been put forward on the
+subject.  The place for the experiment was, with the consent of every
+member of the Committee, selected by the late Admiral Sir W.J. Wharton--who
+was not himself an adherent of Darwin's views--and no one has ventured to
+suggest that his selection, the splendid atoll of Funafuti, was not a most
+judicious one.
+
+By the pluck and perseverance of Professor Sollas in the preliminary
+expedition, and of Professor T. Edgeworth David and his pupils, in
+subsequent investigations of the island, the rather difficult piece of work
+was brought to a highly satisfactory conclusion.  The New South Wales
+Government lent boring apparatus and workmen, and the Admiralty carried the
+expedition to its destination in a surveying ship which, under Captain (now
+Admiral) A. Mostyn Field, made the most complete survey of the atoll and
+its surrounding seas that has ever been undertaken in the case of a coral
+formation.
+
+After some failures and many interruptions, the boring was carried to the
+depth of 1114 feet, and the cores obtained were sent to England.  Here the
+examination of the materials was fortunately undertaken by a zoologist of
+the highest repute, Dr G.J. Hinde--who has a wide experience in the study
+of organisms by sections--and he was aided at all points by specialists in
+the British Museum of Natural History and by other naturalists.  Nor were
+the chemical and other problems neglected.
+
+The verdict arrived at, after this most exhaustive study of a series of
+cores obtained from depths twice as great as that thought necessary by
+Darwin, was as follows:--"The whole of the cores are found to be built up
+of those organisms which are seen forming coral-reefs near the surface of
+the ocean--many of them evidently in situ; and not the slightest indication
+could be detected, by chemical or microscopic means, which suggested the
+proximity of non-calcareous rocks, even in the lowest portions brought up."
+
+But this was not all.  Professor David succeeded in obtaining the aid of a
+very skilful engineer from Australia, while the Admiralty allowed Commander
+F.C.D. Sturdee to take a surveying ship into the lagoon for further
+investigations.  By very ingenious methods, and with great perseverance,
+two borings were put down in the midst of the lagoon to the depth of nearly
+200 feet.  The bottom of the lagoon, at the depth of 101 1/2 feet from sea-
+level, was found to be covered with remains of the calcareous, green sea-
+weed Halimeda, mingled with many foraminifera; but at a depth of 163 feet
+from the surface of the lagoon the boring tools encountered great masses of
+coral, which were proved from the fragments brought up to belong to species
+that live within AT MOST 120 feet from the surface of the ocean, as
+admitted by all zoologists.  ("The Atoll of Funafuti; Report of the Coral
+Reef Committee of the Royal Society", London, 1904.)
+
+Darwin's theory, as is well known, is based on the fact that the
+temperature of the ocean at any considerable depth does not permit of the
+existence and luxuriant growth of the organisms that form the reefs.  He
+himself estimated this limit of depth to be from 120 to 130 feet; Dana, as
+an extreme, 150 feet; while the recent very prolonged and successful
+investigations of Professor Alexander Agassiz in the Pacific and Indian
+Oceans lead him also to assign a limiting depth of 150 feet; the EFFECTIVE,
+REEF-FORMING CORALS, however, flourishing at a much smaller depth.  Mr
+Stanley Gardiner gives for the most important reef-forming corals depths
+between 30 and 90 feet, while a few are found as low as 120 feet or even
+180 feet.
+
+It will thus be seen that the verdict of Funafuti is clearly and
+unmistakeably in favour of Darwin's theory.  It is true that some
+zoologists find a difficulty in realising a slow sinking of parts of the
+ocean floor, and have suggested new and alternative explanations:  but
+geologists generally, accepting the proofs of slow upheaval in some areas--
+as shown by the admirable researches of Alexander Agassiz--consider that it
+is absolutely necessary to admit that this elevation is balanced by
+subsidence in other areas.  If atolls and barrier-reefs did not exist we
+should indeed be at a great loss to frame a theory to account for their
+absence.
+
+After finishing his book on Coral-reefs, Darwin made his summer excursion
+to North Wales, and prepared his important memoir on the glaciers of that
+district:  but by October (1842) we find him fairly settled at work upon
+the second volume of his "Geology of the 'Beagle'--Geological Observations
+on the Volcanic Islands, visited during the Voyage of H.M.S. 'Beagle'". 
+The whole of the year 1843 was devoted to this work, but he tells his
+friend Fox that he could "manage only a couple of hours per day, and that
+not very regularly."  ("L.L." I. page 321.)  Darwin's work on the various
+volcanic islands examined by him had given him the most intense pleasure,
+but the work of writing the book by the aid of his notes and specimens he
+found "uphill work," especially as he feared the book would not be read,
+"even by geologists."  (Loc. cit.)
+
+As a matter of fact the work is full of the most interesting observations
+and valuable suggestions, and the three editions (or reprints) which have
+appeared have proved a most valuable addition to geological literature.  It
+is not necessary to refer to the novel and often very striking discoveries
+described in this well-known work.  The subsidence beneath volcanic vents,
+the enormous denudation of volcanic cones reducing them to "basal wrecks,"
+the effects of solfatarric action and the formation of various minerals in
+the cavities of rocks--all of these subjects find admirable illustration
+from his graphic descriptions.  One of the most important discussions in
+this volume is that dealing with the "lamination" of lavas as especially
+well seen in the rocks of Ascension.  Like Scrope, Darwin recognised the
+close analogy between the structure of these rocks and those of metamorphic
+origin--a subject which he followed out in the volume "Geological
+Observations on South America".
+
+Of course in these days, since the application of the microscope to the
+study of rocks in thin sections, Darwin's nomenclature and descriptions of
+the petrological characters of the lavas appear to us somewhat crude.  But
+it happened that the "Challenger" visited most of the volcanic islands
+described by Darwin, and the specimens brought home were examined by the
+eminent petrologist Professor Renard.  Renard was so struck with the work
+done by Darwin, under disadvantageous conditions, that he undertook a
+translation of Darwin's work into French, and I cannot better indicate the
+manner in which the book is regarded by geologists than by quoting a
+passage from Renard's preface.  Referring to his own work in studying the
+rocks brought home by the "Challenger" (Renard's descriptions of these
+rocks are contained in the "Challenger Reports".  Mr Harker is
+supplementing these descriptions by a series of petrological memoirs on
+Darwin's specimens, the first of which appeared in the "Geological
+Magazine" for March, 1907.), he says:
+
+"Je dus, en me livrant a ces recherches, suivre ligne par ligne les divers
+chapitres des "Observations geologiques" consacrees aux iles de
+l'Atlantique, oblige que j'etais de comparer d'une maniere suivie les
+resultats auxquels j'etais conduit avec ceux de Darwin, qui servaient de
+controle a mes constatations.  Je ne tardai pas a eprouver une vive
+admiration pour ce chercheur qui, sans autre appareil que la loupe, sans
+autre reaction que quelques essais pyrognostiques, plus rarement quelques
+mesures au goniometre, parvenait a discerner la nature des agregats
+mineralogiques les plue complexes et les plus varies.  Ce coup d'oeil qui
+savait embrasser de si vastes horizons, penetre ici profondement tous les
+details lithologiques.  Avec quelle surete et quelle exactitude la
+structure et la composition des roches ne sont'elles pas determinees,
+l'origne de ces masses minerales deduite et confirmee par l'etude comparee
+des manifestations volcaniques d'autres regions; avec quelle science les
+relations entre les faits qu'il decouvre et ceux signales ailleurs par ses
+devanciers ne sont'elles pas etablies, et comme voici ebranlees les
+hypotheses regnantes, admises sans preuves, celles, par exemple, des
+crateres de soulevement et de la differenciation radicale des phenomenes
+plutoniques et volcaniques!  Ce qui acheve de donner a ce livre un
+incomparable merite, ce sont les idees nouvelles qui s'y trouvent en germe
+et jetees la comme au hasard ainsi qu'un superflu d'abondance
+intellectuelle inepuisable."  ("Observations Geologiques sur les Iles
+Volcaniques...", Paris, 1902, pages vi., vii.)
+
+While engaged in his study of banded lavas, Darwin was struck with the
+analogy of their structure with that of glacier ice, and a note on the
+subject, in the form of a letter addressed to Professor J.D. Forbes, was
+published in the "Proceedings of the Royal Society of Edinburgh".  (Vol.
+II. (1844-5), pages 17, 18.)
+
+From April, 1832, to September, 1835, Darwin had been occupied in examining
+the coast or making inland journeys in the interior of the South American
+continent.  Thus while eighteen months were devoted, at the beginning and
+end of the voyage to the study of volcanic islands and coral-reefs, no less
+than three and a half years were given to South American geology.  The
+heavy task of dealing with the notes and specimens accumulated during that
+long period was left by Darwin to the last.  Finishing the "Volcanic
+Islands" on February 14th, 1844, he, in July of the same year, commenced
+the preparation of two important works which engaged him till near the end
+of the year 1846.  The first was his "Geological Observations on South
+America", the second a recast of his "Journal", published under the short
+title of "A Naturalist's Voyage round the World".
+
+The first of these works contains an immense amount of information
+collected by the author under great difficulties and not unfrequently at
+considerable risk to life and health.  No sooner had Darwin landed in South
+America than two sets of phenomena powerfully arrested his attention.  The
+first of these was the occurrence of great masses of red mud containing
+bones and shells, which afforded striking evidence that the whole continent
+had shared in a series of slow and gradual but often interrupted movements.
+The second related to the great masses of crystalline rocks which,
+underlying the muds, cover so great a part of the continent.  Darwin,
+almost as soon as he landed, was struck by the circumstance that the
+direction, as shown by his compass, of the prominent features of these
+great crystalline rock-masses--their cleavage, master-joints, foliation and
+pegmatite veins--was the same as the orientation described by Humboldt
+(whose works he had so carefully studied) on the west of the same great
+continent.
+
+The first five chapters of the book on South America were devoted to
+formations of recent date and to the evidence collected on the east and
+west coasts of the continent in regard to those grand earth-movements, some
+of which could be shown to have been accompanied by earthquake-shocks.  The
+fossil bones, which had given him the first hint concerning the mutability
+of species, had by this time been studied and described by comparative
+anatomists, and Darwin was able to elaborate much more fully the important
+conclusion that the existing fauna of South America has a close analogy
+with that of the period immediately preceding our own.
+
+The remaining three chapters of the book dealt with the metamorphic and
+plutonic rocks, and in them Darwin announced his important conclusions
+concerning the relations of cleavage and foliation, and on the close
+analogy of the latter structure with the banding found in rock-masses of
+igneous origin.  With respect to the first of these conclusions, he
+received the powerful support of Daniel Sharpe, who in the years 1852 and
+1854 published two papers on the structure of the Scottish Highlands,
+supplying striking confirmation of the correctness of Darwin's views. 
+Although Darwin's and Sharpe's conclusions were contested by Murchison and
+other geologists, they are now universally accepted.  In his theory
+concerning the origin of foliation, Darwin had been to some extent
+anticipated by Scrope, but he supplied many facts and illustrations leading
+to the gradual acceptance of a doctrine which, when first enunciated, was
+treated with neglect, if not with contempt.
+
+The whole of this volume on South American geology is crowded with the
+records of patient observations and suggestions of the greatest value; but,
+as Darwin himself saw, it was a book for the working geologist and "caviare
+to the general."  Its author, indeed, frequently expressed his sense of the
+"dryness" of the book; he even says "I long hesitated whether I would
+publish it or not," and he wrote to Leonard Horner "I am astonished that
+you should have had the courage to go right through my book."  ("M.L." II.
+page 221.)
+
+Fortunately the second book, on which Darwin was engaged at this time, was
+of a very different character.  His "Journal", almost as he had written it
+on board ship, with facts and observations fresh in his mind, had been
+published in 1839 and attracted much attention.  In 1845, he says, "I took
+much pains in correcting a new edition," and the work which was commenced
+in April, 1845, was not finished till August of that year.  The volume
+contains a history of the voyage with "a sketch of those observations in
+Natural History and Geology, which I think will possess some interest for
+the general reader."  It is not necessary to speak of the merits of this
+scientific classic.  It became a great favourite with the general public--
+having passed through many editions--it was, moreover, translated into a
+number of different languages.  Darwin was much gratified by these
+evidences of popularity, and naively remarks in his "Autobiography", "The
+success of this my first literary child tickles my vanity more than that of
+any of my other books" ("L.L." I. page 80.)--and this was written after the
+"Origin of Species" had become famous!
+
+In Darwin's letters there are many evidences that his labours during these
+ten years devoted to the working out of the geological results of the
+voyage often made many demands on his patience and indomitable courage. 
+Most geologists have experience of the contrast between the pleasures felt
+when wielding the hammer in the field, and the duller labour of plying the
+pen in the study.  But in Darwin's case, innumerable interruptions from
+sickness and other causes, and the oft-deferred hope of reaching the end of
+his task were not the only causes operating to make the work irksome.  The
+great project, which was destined to become the crowning achievement of his
+life, was now gradually assuming more definite shape, and absorbing more of
+his time and energies.
+
+Nevertheless, during all this period, Darwin so far regarded his geological
+pursuits as his PROPER "work," that attention to other matters was always
+spoken of by him as "indulging in idleness."  If at the end of this period
+the world had sustained the great misfortune of losing Darwin by death
+before the age of forty--and several times that event seemed only too
+probable--he might have been remembered only as a very able geologist of
+most advanced views, and a traveller who had written a scientific narrative
+of more than ordinary excellence!
+
+The completion of the "Geology of the 'Beagle'" and the preparation of a
+revised narrative of the voyage mark the termination of that period of
+fifteen years of Darwin's life during which geological studies were his
+principal occupation.  Henceforth, though his interest in geological
+questions remained ever keen, biological problems engaged more and more of
+his attention to the partial exclusion of geology.
+
+The eight years from October, 1846, to October, 1854, were mainly devoted
+to the preparation of his two important monographs on the recent and fossil
+Cirripedia.  Apart from the value of his description of the fossil forms,
+this work of Darwin's had an important influence on the progress of
+geological science.  Up to that time a practice had prevailed for the
+student of a particular geological formation to take up the description of
+the plant and animal remains in it--often without having anything more than
+a rudimentary knowledge of the living forms corresponding to them.  Darwin
+in his monograph gave a very admirable illustration of the enormous
+advantage to be gained--alike for biology and geology--by undertaking the
+study of the living and fossil forms of a natural group of organisms in
+connection with one another.  Of the advantage of these eight years of work
+to Darwin himself, in preparing for the great task lying before him, Huxley
+has expressed a very strong opinion indeed.  ("L.L." II. pages 247-48.)
+
+But during these eight years of "species work," Darwin found opportunities
+for not a few excursions into the field of geology.  He occasionally
+attended the Geological Society, and, as we have already seen, read several
+papers there during this period.  His friend, Dr Hooker, then acting as
+botanist to the Geological Survey, was engaged in studying the
+Carboniferous flora, and many discussions on Palaezoic plants and on the
+origin of coal took place at this period.  On this last subject he felt the
+deepest interest and told Hooker, "I shall never rest easy in Down
+churchyard without the problem be solved by some one before I die." 
+("M.L." I. pages 63, 64.)
+
+As at all times, conversations and letters with Lyell on every branch of
+geological science continued with unabated vigour, and in spite of the
+absorbing character of the work on the Cirripedes, time was found for all. 
+In 1849 his friend Herschel induced him to supply a chapter of forty pages
+on Geology to the Admiralty "Manual of Scientific Inquiry" which he was
+editing.  This is Darwin's single contribution to books of an "educational"
+kind.  It is remarkable for its clearness and simplicity and attention to
+minute details.  It may be read by the student of Darwin's life with much
+interest, for the directions he gives to an explorer are without doubt
+those which he, as a self-taught geologist, proved to be serviceable during
+his life on the "Beagle".
+
+On the completion of the Cirripede volumes, in 1854, Darwin was able to
+grapple with the immense pile of MS. notes which he had accumulated on the
+species question.  The first sketch of 35 pages (1842), had been enlarged
+in 1844 into one of 230 pages ([The first draft of the "Origin" is being
+prepared for Press by Mr Francis Darwin and will be published by the
+Cambridge University Press this year (1909).  A.C.S.]); but in 1856 was
+commenced the work (never to be completed) which was designed on a scale
+three or four times more extensive than that on which the "Origin of
+Species" was in the end written.
+
+In drawing up those two masterly chapters of the "Origin", "On the
+Imperfection of the Geological Record," and "On the Geological Succession
+of Organic Beings", Darwin had need of all the experience and knowledge he
+had been gathering during thirty years, the first half of which had been
+almost wholly devoted to geological study.  The most enlightened geologists
+of the day found much that was new, and still more that was startling from
+the manner of its presentation, in these wonderful essays.  Of Darwin's own
+sense of the importance of the geological evidence in any presentation of
+his theory a striking proof will be found in a passage of the touching
+letter to his wife, enjoining the publication of his sketch of 1844.  "In
+case of my sudden death," he wrote, "...the editor must be a geologist as
+well as a naturalist."  ("L.L." II. pages 16, 17.)
+
+In spite of the numerous and valuable palaeontological discoveries made
+since the publication of "The Origin of Species", the importance of the
+first of these two geological chapters is as great as ever.  It still
+remains true that "Those who believe that the geological record is in any
+degree perfect, will at once reject the theory"--as indeed they must reject
+any theory of evolution.  The striking passage with which Darwin concludes
+this chapter--in which he compares the record of the rocks to the much
+mutilated volumes of a human history--remains as apt an illustration as it
+did when first written.
+
+And the second geological chapter, on the Succession of Organic Beings--
+though it has been strengthened in a thousand ways, by the discoveries
+concerning the pedigrees of the horse, the elephant and many other aberrant
+types, though new light has been thrown even on the origin of great groups
+like the mammals, and the gymnosperms, though not a few fresh links have
+been discovered in the chains of evidence, concerning the order of
+appearance of new forms of life--we would not wish to have re-written. 
+Only the same line of argument could be adopted, though with innumerable
+fresh illustrations.  Those who reject the reasonings of this chapter,
+neither would they be persuaded if a long and complete succession of
+"ancestral forms" could rise from the dead and pass in procession before
+them.
+
+Among the geological discussions, which so frequently occupied Darwin's
+attention during the later years of his life, there was one concerning
+which his attitude seemed somewhat remarkable--I allude to his views on
+"the permanence of Continents and Ocean-basins."  In a letter to Mr Mellard
+Reade, written at the end of 1880, he wrote:  "On the whole, I lean to the
+side that the continents have since Cambrian times occupied approximately
+their present positions.  But, as I have said, the question seems a
+difficult one, and the more it is discussed the better."  ("M.L." II. page
+147.)  Since this was written, the important contribution to the subject by
+the late Dr W.T. Blanford (himself, like Darwin, a naturalist and
+geologist) has appeared in an address to the Geological Society in 1890;
+and many discoveries, like that of Dr Woolnough in Fiji, have led to
+considerable qualifications of the generalisation that all the islands in
+the great ocean are wholly of volcanic or coral origin.
+
+I remember once expressing surprise to Darwin that, after the views which
+he had originated concerning the existence of areas of elevation and others
+of subsidence in the Pacific Ocean, and in face of the admitted difficulty
+of accounting for the distribution of certain terrestrial animals and
+plants, if the land and sea areas had been permanent in position, he still
+maintained that theory.  Looking at me with a whimsical smile, he said:  "I
+have seen many of my old friends make fools of themselves, by putting
+forward new theoretical views or revising old ones, AFTER THEY WERE SIXTY
+YEARS OF AGE; so, long ago, I determined that on reaching that age I would
+write nothing more of a speculative character."
+
+Though Darwin's letters and conversations on geology during these later
+years were the chief manifestations of the interest he preserved in his
+"old love," as he continued to call it, yet in the sunset of that active
+life a gleam of the old enthusiasm for geology broke forth once more. 
+There can be no doubt that Darwin's inability to occupy himself with field-
+work proved an insuperable difficulty to any attempt on his part to resume
+active geological research.  But, as is shown by the series of charming
+volumes on plant-life, Darwin had found compensation in making patient and
+persevering experiment take the place of enterprising and exact
+observation; and there was one direction in which he could indulge the "old
+love" by employment of the new faculty.
+
+We have seen that the earliest memoir written by Darwin, which was
+published in full, was a paper "On the Formation of Mould" which was read
+at the Geological Society on November 1st, 1837, but did not appear in the
+"Transactions" of the Society till 1840, where it occupied four and a half
+quarto pages, including some supplementary matter, obtained later, and a
+woodcut.  This little paper was confined to observations made in his
+uncle's fields in Staffordshire, where burnt clay, cinders, and sand were
+found to be buried under a layer of black earth, evidently brought from
+below by earthworms, and to a recital of similar facts from Scotland
+obtained through the agency of Lyell.  The subsequent history of Darwin's
+work on this question affords a striking example of the tenacity of purpose
+with which he continued his enquiries on any subject that interested him.
+
+In 1842, as soon as he was settled at Down, he began a series of
+observations on a foot-path and in his fields, that continued with
+intermissions during his whole life, and he extended his enquiries from
+time to time to the neighbouring parks of Knole and Holwood.  In 1844 we
+find him making a communication to the "Gardener's Chronicle" on the
+subject.  About 1870, his attention to the question was stimulated by the
+circumstance that his niece (Miss L. Wedgwood) undertook to collect and
+weigh the worm-casts thrown up, during a whole year, on measured squares
+selected for the purpose, at Leith Hill Place.  He also obtained
+information from Professor Ramsay concerning observations made by him on a
+pavement near his house in 1871.  Darwin at this time began to realise the
+great importance of the action of worms to the archaeologist.  At an
+earlier date he appears to have obtained some information concerning
+articles found buried on the battle-field of Shrewsbury, and the old Roman
+town of Uriconium, near his early home; between 1871 and 1878 Mr
+(afterwards Lord) Farrer carried on a series of investigations at the Roman
+Villa discovered on his land at Abinger; Darwin's son William examined for
+his father the evidence at Beaulieu Abbey, Brading, Stonehenge and other
+localities in the neighbourhood of his home; his sons Francis and Horace
+were enlisted to make similar enquiries at Chideock and Silchester; while
+Francis Galton contributed facts noticed in his walks in Hyde Park.  By
+correspondence with Fritz Muller and Dr Ernst, Darwin obtained information
+concerning the worm-casts found in South America; from Dr Kreft those of
+Australia; and from Mr Scott and Dr (afterwards Sir George) King, those of
+India; the last-named correspondent also supplied him with much valuable
+information obtained in the South of Europe.  Help too was obtained from
+the memoirs on Earthworms published by Perrier in 1874 and van Hensen in
+1877, while Professor Ray Lankester supplied important facts with regard to
+their anatomy.
+
+When therefore the series of interesting monographs on plant-life had been
+completed, Darwin set to work in bringing the information that he had
+gradually accumulated during forty-four years to bear on the subject of his
+early paper.  He also utilised the skill and ingenuity he had acquired in
+botanical work to aid in the elucidation of many of the difficulties that
+presented themselves.  I well remember a visit which I paid to Down at this
+period.  At the side of the little study stood flower-pots containing earth
+with worms, and, without interrupting our conversation, Darwin would from
+time to time lift the glass plate covering a pot to watch what was going
+on.  Occasionally, with a humorous smile, he would murmur something about a
+book in another room, and slip away; returning shortly, without the book
+but with unmistakeable signs of having visited the snuff-jar outside. 
+After working about a year at the worms, he was able at the end of 1881 to
+publish the charming little book--"The Formation of Vegetable Mould through
+the Action of Worms, with Observations on their Habits".  This was the last
+of his books, and its reception by reviewers and the public alike afforded
+the patient old worker no little gratification.  Darwin's scientific
+career, which had begun with geological research, most appropriately ended
+with a return to it.
+
+It has been impossible to sketch the origin and influence of Darwin's
+geological work without, at almost every step, referring to the part played
+by Lyell and the "Principles of Geology".  Haeckel, in the chapters on
+Lyell and Darwin in his "History of Creation", and Huxley in his striking
+essay "On the Reception of the Origin of Species" ("L.L." II. pages 179-
+204.) have both strongly insisted on the fact that the "Origin" of Darwin
+was a necessary corollary to the "Principles" of Lyell.
+
+It is true that, in an earlier essay, Huxley had spoken of the doctrine of
+Uniformitarianism as being, in a certain sense, opposed to that of
+Evolution (Huxley's Address to the Geological Society, 1869.  "Collected
+Essays", Vol. VIII. page 305, London, 1896.); but in his later years he
+took up a very different and more logical position, and maintained that
+"Consistent uniformitarianism postulates evolution as much in the organic
+as in the inorganic world.  The origin of a new species by other than
+ordinary agencies would be a vastly greater 'catastrophe' than any of those
+which Lyell success fully eliminated from sober geological speculation." 
+("L.L." II. page 190.)
+
+Huxley's admiration for the "Principles of Geology", and his conviction of
+the greatness of the revolution of thought brought about by Lyell, was
+almost as marked as in the case of Darwin himself.  (See his Essay on
+"Science and Pseudo Science".  "Collected Essays", Vol. V. page 90, London,
+1902.)  He felt, however, as many others have done, that in one respect the
+very success of Lyell's masterpiece has been the reason why its originality
+and influence have not been so fully recognised as they deserved to be. 
+Written as the book was before its author had arrived at the age of thirty,
+no less than eleven editions of the "Principles" were called for in his
+lifetime.  With the most scrupulous care, Lyell, devoting all his time and
+energies to the task of collecting and sifting all evidence bearing on the
+subjects of his work, revised and re-revised it; and as in each edition,
+eliminations, modifications, corrections, and additions were made, the
+book, while it increased in value as a storehouse of facts, lost much of
+its freshness, vigour and charm as a piece of connected reasoning.
+
+Darwin undoubtedly realised this when he wrote concerning the "Principles",
+"the first edition, my old true love, which I never deserted for the later
+editions."  ("M.L." II. page 222.)  Huxley once told me that when, in later
+life, he read the first edition, he was both surprised and delighted,
+feeling as if it were a new book to him.  (I have before me a letter which
+illustrates this feeling on Huxley's part.  He had lamented to me that he
+did not possess a copy of the first edition of the "Principles", when,
+shortly afterwards, I picked up a dilapidated copy on a bookstall; this I
+had bound and sent to my old teacher and colleague.  His reply is
+characteristic:
+
+October 8, 1884.
+
+My Dear Judd,
+
+You could not have made me a more agreeable present than the copy of the
+first edition of Lyell, which I find on my table.  I have never been able
+to meet with the book, and your copy is, as the old woman said of her
+Bible, "the best of books in the best of bindings."
+
+Ever yours sincerely,
+
+T.H. Huxley.
+
+I cannot refrain from relating an incident which very strikingly
+exemplifies the affection for one another felt by Lyell and Huxley.  In his
+last illness, when confined to his bed, Lyell heard that Huxley was to
+lecture at the Royal Institution on the "Results of the 'Challenger'
+expedition":  he begged me to attend the lecture and bring him an account
+of it.  Happening to mention this to Huxley, he at once undertook to go to
+Lyell in my place, and he did so on the morning following his lecture.  I
+shall never forget the look of gratitude on the face of the invalid when he
+told me, shortly afterwards, how Huxley had sat by his bedside and
+"repeated the whole lecture to him.")
+
+Darwin's generous nature seems often to have made him experience a fear
+lest he should do less than justice to his "dear old master," and to the
+influence that the "Principles of Geology" had in moulding his mind.  In
+1845 he wrote to Lyell, "I have long wished, not so much for your sake, as
+for my own feelings of honesty, to acknowledge more plainly than by mere
+reference, how much I geologically owe you.  Those authors, however, who
+like you, educate people's minds as well as teach them special facts, can
+never, I should think, have full justice done them except by posterity, for
+the mind thus insensibly improved can hardly perceive its own upward
+ascent."  ("L.L." I. pages 337-8.)  In another letter, to Leonard Horner,
+he says:  "I always feel as if my books came half out of Lyell's brain, and
+that I never acknowledge this sufficiently."  ("M.L." II. page 117.) 
+Darwin's own most favourite book, the "Narrative of the Voyage", was
+dedicated to Lyell in glowing terms; and in the "Origin of Species" he
+wrote of "Lyell's grand work on the "Principles of Geology", which the
+future historian will recognise as having produced a revolution in Natural
+Science."  "What glorious good that work has done" he fervently exclaims on
+another occasion.  ("L.L." I. page 342.)
+
+To the very end of his life, as all who were in the habit of talking with
+Darwin can testify, this sense of his indebtedness to Lyell remained with
+him.  In his "Autobiography", written in 1876, the year after Lyell's
+death, he spoke in the warmest terms of the value to him of the
+"Principles" while on the voyage and of the aid afforded to him by Lyell on
+his return to England.  ("L.L." I. page 62.)  But the year before his own
+death, Darwin felt constrained to return to the subject and to place on
+record a final appreciation--one as honourable to the writer as it is to
+his lost friend:
+
+"I saw more of Lyell than of any other man, both before and after my
+marriage.  His mind was characterised, as it appeared to me, by clearness,
+caution, sound judgment, and a good deal of originality.  When I made any
+remark to him on Geology, he never rested until he saw the whole case
+clearly, and often made me see it more clearly than I had done before.  He
+would advance all possible objections to my suggestion, and even after
+these were exhausted would remain long dubious.  A second characteristic
+was his hearty sympathy with the work of other scientific men...His delight
+in science was ardent, and he felt the keenest interest in the future
+progress of mankind.  He was very kind-hearted...His candour was highly
+remarkable.  He exhibited this by becoming a convert to the Descent theory,
+though he had gained much fame by opposing Lamarck's views, and this after
+he had grown old."
+
+"THE SCIENCE OF GEOLOGY IS ENORMOUSLY INDEBTED TO LYELL--MORE SO, AS I
+BELIEVE, THAN TO ANY OTHER MAN WHO EVER LIVED."  ("L.L." I. pages 71-2 (the
+italics are mine.)
+
+Those who knew Lyell intimately will recognise the truth of the portrait
+drawn by his dearest friend, and I believe that posterity will endorse
+Darwin's deliberate verdict concerning the value of his labours.
+
+It was my own good fortune, to be brought into close contact with these two
+great men during the later years of their life, and I may perhaps be
+permitted to put on record the impressions made upon me during friendly
+intercourse with both.
+
+In some respects, there was an extraordinary resemblance in their modes and
+habits of thought, between Lyell and Darwin; and this likeness was also
+seen in their modesty, their deference to the opinion of younger men, their
+enthusiasm for science, their freedom from petty jealousies and their
+righteous indignation for what was mean and unworthy in others.  But yet
+there was a difference.  Both Lyell and Darwin were cautious, but perhaps
+Lyell carried his caution to the verge of timidity.  I think Darwin
+possessed, and Lyell lacked, what I can only describe by the theological
+term, "faith--the substance of things hoped for, the evidence of things not
+seen."  Both had been constrained to feel that the immutability of species
+could not be maintained.  Both, too, recognised the fact that it would be
+useless to proclaim this conviction, unless prepared with a satisfactory
+alternative to what Huxley called "the Miltonic hypothesis."  But Darwin's
+conviction was so far vital and operative that it sustained him while
+working unceasingly for twenty-two years in collecting evidence bearing on
+the question, till at last he was in the position of being able to justify
+that conviction to others.
+
+And yet Lyell's attitude--and that of Hooker, which was very similar--
+proved of inestimable service to science, as Darwin often acknowledged. 
+One of the greatest merits of the "Origin of Species" is that so many
+difficulties and objections are anticipated and fairly met; and this was to
+a great extent the result of the persistent and very candid--if always
+friendly--criticism of Lyell and Hooker.
+
+I think the divergence of mental attitude in Lyell and Darwin must be
+attributed to a difference in temperament, the evidence of which sometimes
+appears in a very striking manner in their correspondence.  Thus in 1838,
+while they were in the thick of the fight with the Catastrophists of the
+Geological Society, Lyell wrote characteristically:  "I really find, when
+bringing up my Preliminary Essays in "Principles" to the science of the
+present day, so far as I know it, that the great outline, and even most of
+the details, stand so uninjured, and in many cases they are so much
+strengthened by new discoveries, especially by yours, that we may begin to
+hope that the great principles there insisted on will stand the test of new
+discoveries."  (Lyell's "Life, Letters and Journals", Vol. II. page 44.) 
+To which the more youthful and impetuous Darwin replies:  "BEGIN TO HOPE: 
+why the POSSIBILITY of a doubt has never crossed my mind for many a day. 
+This may be very unphilosophical, but my geological salvation is staked on
+it...it makes me quite indignant that you should talk of HOPING."  ("L.L."
+I. page 296.)
+
+It was not only Darwin's "geological salvation" that was at stake, when he
+surrendered himself to his enthusiasm for an idea.  To his firm faith in
+the doctrine of continuity we owe the "Origin of Species"; and while Darwin
+became the "Paul" of evolution, Lyell long remained the "doubting Thomas."
+
+Many must have felt like H.C. Watson when he wrote:  "How could Sir C.
+Lyell...for thirty years read, write, and think, on the subject of species
+AND THEIR SUCCESSION, and yet constantly look down the wrong road!" ("L.L."
+II. page 227.)  Huxley attributed this hesitation of Lyell to his "profound
+antipathy" to the doctrine of the "pithecoid origin of man."  ("L.L." II.
+page 193.)  Without denying that this had considerable influence (and those
+who knew Lyell and his great devotion to his wife and her memory, are aware
+that he and she felt much stronger convictions concerning such subjects as
+the immortality of the soul than Darwin was able to confess to) yet I think
+Darwin had divined the real characteristics of his friend's mind, when he
+wrote:  "He would advance all possible objections...AND EVEN AFTER THESE
+WERE EXHAUSTED, WOULD REMAIN LONG DUBIOUS."
+
+Very touching indeed was the friendship maintained to the end between these
+two leaders of thought--free as their intercourse was from any smallest
+trace of self-seeking or jealousy.  When in 1874 I spent some time with
+Lyell in his Forfarshire home, a communication from Darwin was always an
+event which made a "red-letter day," as Lyell used to say; and he gave me
+many indications in his conversation of how strongly he relied upon the
+opinion of Darwin--more indeed than on the judgment of any other man--this
+confidence not being confined to questions of science, but extending to
+those of morals, politics, and religion.
+
+I have heard those who knew Lyell only slightly, speak of his manners as
+cold and reserved.  His complete absorption in his scientific work, coupled
+with extreme short-sightedness, almost in the end amounting to blindness,
+may have permitted those having but a casual acquaintance with him to
+accept such a view.  But those privileged to know him intimately recognised
+the nobleness of his character and can realise the justice and force of
+Hooker's words when he heard of his death:  "My loved, my best friend, for
+well nigh forty years of my life.  The most generous sharer of my own and
+my family's hopes, joys and sorrows, whose affection for me was truly that
+of a father and brother combined."
+
+But the strongest of all testimonies to the grandeur of Lyell's character
+is the lifelong devotion to him of such a man as Darwin.  Before the two
+met, we find Darwin constantly writing of facts and observations that he
+thinks "will interest Mr Lyell"; and when they came together the mutual
+esteem rapidly ripened into the warmest affection.  Both having the
+advantage of a moderate independence, permitting of an entire devotion of
+their lives to scientific research, they had much in common, and the elder
+man--who had already achieved both scientific and literary distinction--was
+able to give good advice and friendly help to the younger one.  The warmth
+of their friendship comes out very strikingly in their correspondence. 
+When Darwin first conceived the idea of writing a book on the "species
+question," soon after his return from the voyage, it was "by following the
+example of Lyell in Geology" that he hoped to succeed ("L.L." I. page 83.);
+when in 1844, Darwin had finished his first sketch of the work, and,
+fearing that his life might not be spared to complete his great
+undertaking, committed the care of it in a touching letter to his wife, it
+was his friend Lyell whom he named as her adviser and the possible editor
+of the book ("L.L." II. pages 17-18.); it was Lyell who, in 1856, induced
+Darwin to lay the foundations of a treatise ("L.L." I. page 84.) for which
+the author himself selected the "Principles" as his model; and when the
+dilemma arose from the receipt of Wallace's essay, it was to Lyell jointly
+with Hooker that Darwin turned, not in vain, for advice and help.
+
+During the later years of his life, I never heard Darwin allude to his lost
+friend--and he did so very often--without coupling his name with some term
+of affection.  For a brief period, it is true, Lyell's excessive caution
+when the "Origin" was published, seemed to try even the patience of Darwin;
+but when "the master" was at last able to declare himself fully convinced,
+he was the occasion of more rejoicing on the part of Darwin, than any other
+convert to his views.  The latter was never tired of talking of Lyell's
+"magnanimity" and asserted that, "To have maintained in the position of a
+master, one side of a question for thirty years, and then deliberately give
+it up, is a fact to which I much doubt whether the records of science offer
+a parallel."  ("L.L." II. pages 229-30.)
+
+Of Darwin himself, I can safely affirm that I never knew anyone who had met
+him, even for the briefest period, who was not charmed by his personality.
+Who could forget the hearty hand-grip at meeting, the gentle and lingering
+pressure of the palm at parting, and above all that winning smile which
+transformed his countenance--so as to make portraits, and even photographs,
+seem ever afterwards unsatisfying!  Looking back, one is indeed tempted to
+forget the profoundness of the philosopher, in recollection of the
+loveableness of the man.
+
+
+XIX.  DARWIN'S WORK ON THE MOVEMENTS OF PLANTS.
+
+By FRANCIS DARWIN,
+Honorary Fellow of Christ's College, Cambridge.
+
+My father's interest in plants was of two kinds, which may be roughly
+distinguished as EVOLUTIONARY and PHYSIOLOGICAL.  Thus in his purely
+evolutionary work, for instance in "The Origin of Species" and in his book
+on "Variation under Domestication", plants as well as animals served as
+material for his generalisations.  He was largely dependent on the work of
+others for the facts used in the evolutionary work, and despised himself
+for belonging to the "blessed gang" of compilers.  And he correspondingly
+rejoiced in the employment of his wonderful power of observation in the
+physiological problems which occupied so much of his later life.  But
+inasmuch as he felt evolution to be his life's work, he regarded himself as
+something of an idler in observing climbing plants, insectivorous plants,
+orchids, etc.  In this physiological work he was to a large extent urged on
+by his passionate desire to understand the machinery of all living things. 
+But though it is true that he worked at physiological problems in the
+naturalist's spirit of curiosity, yet there was always present to him the
+bearing of his facts on the problem of evolution.  His interests,
+physiological and evolutionary, were indeed so interwoven that they cannot
+be sharply separated.  Thus his original interest in the fertilisation of
+flowers was evolutionary.  "I was led" ("Life and Letters", I. page 90.),
+he says, "to attend to the cross-fertilisation of flowers by the aid of
+insects, from having come to the conclusion in my speculations on the
+origin of species, that crossing played an important part in keeping
+specific forms constant."  In the same way the value of his experimental
+work on heterostyled plants crystalised out in his mind into the conclusion
+that the product of illegitimate unions are equivalent to hybrids--a
+conclusion of the greatest interest from an evolutionary point of view. 
+And again his work "Cross and Self Fertilisation" may be condensed to a
+point of view of great importance in reference to the meaning and origin of
+sexual reproduction.  (See Professor Goebel's article in the present
+volume.)
+
+The whole of his physiological work may be looked at as an illustration of
+the potency of his theory as an "instrument for the extension of the realm
+of natural knowledge."  (Huxley in Darwin's "Life and Letters." II. page
+204.)
+
+His doctrine of natural selection gave, as is well known, an impulse to the
+investigation of the use of organs--and thus created the great school of
+what is known in Germany as Biology--a department of science for which no
+English word exists except the rather vague term Natural History.  This was
+especially the case in floral biology, and it is interesting to see with
+what hesitation he at first expressed the value of his book on Orchids
+("Life and Letters", III. page 254.), "It will perhaps serve to illustrate
+how Natural History may be worked under the belief of the modification of
+species" (1861).  And in 1862 he speaks (Loc. cit.) more definitely of the
+relation of his work to natural selection:  "I can show the meaning of some
+of the apparently meaningless ridges (and) horns; who will now venture to
+say that this or that structure is useless?"  It is the fashion now to
+minimise the value of this class of work, and we even find it said by a
+modern writer that to inquire into the ends subserved by organs is not a
+scientific problem.  Those who take this view surely forget that the
+structure of all living things is, as a whole, adaptive, and that a
+knowledge of how the present forms come to be what they are includes a
+knowledge of why they survived.  They forget that the SUMMATION of
+variations on which divergence depends is under the rule of the environment
+considered as a selective force.  They forget that the scientific study of
+the interdependence of organisms is only possible through a knowledge of
+the machinery of the units.  And that, therefore, the investigation of such
+widely interesting subjects as extinction and distribution must include a
+knowledge of function.  It is only those who follow this line of work who
+get to see the importance of minute points of structure and understand as
+my father did even in 1842, as shown in his sketch of the "Origin" (Now
+being prepared for publication.), that every grain of sand counts for
+something in the balance.  Much that is confidently stated about the
+uselessness of different organs would never have been written if the
+naturalist spirit were commoner nowadays.  This spirit is strikingly shown
+in my father's work on the movements of plants.  The circumstance that
+botanists had not, as a class, realised the interest of the subject
+accounts for the fact that he was able to gather such a rich harvest of
+results from such a familiar object as a twining plant.  The subject had
+been investigated by H. von Mohl, Palm, and Dutrochet, but they failed not
+only to master the problem but (which here concerns us) to give the
+absorbing interest of Darwin's book to what they discovered.
+
+His work on climbing plants was his first sustained piece of work on the
+physiology of movement, and he remarks in 1864:  "This has been new sort of
+work for me."  ("Life and Letters", III. page 315.  He had, however, made a
+beginning on the movements of Drosera.)  He goes on to remark with
+something of surprise, "I have been pleased to find what a capital guide
+for observations a full conviction of the change of species is."
+
+It was this point of view that enabled him to develop a broad conception of
+the power of climbing as an adaptation by means of which plants are enabled
+to reach the light.  Instead of being compelled to construct a stem of
+sufficient strength to stand alone, they succeed in the struggle by making
+use of other plants as supports.  He showed that the great class of
+tendril- and root-climbers which do not depend on twining round a pole,
+like a scarlet-runner, but on attaching themselves as they grow upwards,
+effect an economy.  Thus a Phaseolus has to manufacture a stem three feet
+in length to reach a height of two feet above the ground, whereas a pea
+"which had ascended to the same height by the aid of its tendrils, was but
+little longer than the height reached."  ("Climbing Plants" (2nd edition
+1875), page 193.)
+
+Thus he was led on to the belief that TWINING is the more ancient form of
+climbing, and that tendril-climbers have been developed from twiners.  In
+accordance with this view we find LEAF-CLIMBERS, which may be looked on as
+incipient tendril-bearers, occurring in the same genera with simple
+twiners.  (Loc. cit. page 195.)  He called attention to the case of
+Maurandia semperflorens in which the young flower-stalks revolve
+spontaneously and are sensitive to a touch, but neither of these qualities
+is of any perceptible value to the species.  This forced him to believe
+that in other young plants the rudiments of the faculty needed for twining
+would be found--a prophecy which he made good in his "Power of Movement"
+many years later.
+
+In "Climbing Plants" he did little more than point out the remarkable fact
+that the habit of climbing is widely scattered through the vegetable
+kingdom.  Thus climbers are to be found in 35 out of the 59 Phanerogamic
+Alliances of Lindley, so that "the conclusion is forced on our minds that
+the capacity of revolving (If a twining plant, e.g. a hop, is observed
+before it has begun to ascend a pole, it will be noticed that, owing to the
+curvature of the stem, the tip is not vertical but hangs over in a roughly
+horizontal position.  If such a shoot is watched it will be found that if,
+for instance, it points to the north at a given hour, it will be found
+after a short interval pointing north-east, then east, and after about two
+hours it will once more be looking northward.  The curvature of the stem
+depends on one side growing quicker than the opposite side, and the
+revolving movement, i.e. circumnutation, depends on the region of quickest
+growth creeping gradually round the stem from south through west to south
+again.  Other plants, e.g. Phaseolus, revolve in the opposite direction.),
+on which most climbers depend, is inherent, though undeveloped, in almost
+every plant in the vegetable kingdom."  ("Climbing Plants", page 205.)
+
+In the "Origin" (Edition I. page 427, Edition VI. page 374.) Darwin speaks
+of the "apparent paradox, that the very same characters are analogical when
+one class or order is compared with another, but give true affinities when
+the members of the same class or order are compared one with another."  In
+this way we might perhaps say that the climbing of an ivy and a hop are
+analogical; the resemblance depending on the adaptive result rather than on
+community of blood; whereas the relation between a leaf-climber and a true
+tendril-bearer reveals descent.  This particular resemblance was one in
+which my father took especial delight.  He has described an interesting
+case occurring in the Fumariaceae.  ("Climbing Plants", page 195.)  "The
+terminal leaflets of the leaf-climbing Fumaria officinalis are not smaller
+than the other leaflets; those of the leaf-climbing Adlumia cirrhosa are
+greatly reduced; those of Corydalis claviculata (a plant which may be
+indifferently called a leaf-climber or a tendril-bearer) are either reduced
+to microscopical dimensions or have their blades wholly aborted, so that
+this plant is actually in a state of transition; and finally in the
+Dicentra the tendrils are perfectly characterized."
+
+It is a remarkable fact that the quality which, broadly speaking, forms the
+basis of the climbing habit (namely revolving nutation, otherwise known as
+circumnutation) subserves two distinct ends.  One of these is the finding
+of a support, and this is common to twiners and tendrils.  Here the value
+ends as far as tendril-climbers are concerned, but in twiners Darwin
+believed that the act of climbing round a support is a continuation of the
+revolving movement (circumnutation).  If we imagine a man swinging a rope
+round his head and if we suppose the rope to strike a vertical post, the
+free end will twine round it.  This may serve as a rough model of twining
+as explained in the "Movements and Habits of Climbing Plants".  It is on
+these points--the nature of revolving nutation and the mechanism of
+twining--that modern physiologists differ from Darwin.  (See the discussion
+in Pfeffer's "The Physiology of Plants" Eng. Tr. (Oxford, 1906), III. page
+34, where the literature is given.  Also Jost, "Vorlesungen uber
+Pflanzenphysiologie", page 562, Jena, 1904.)
+
+Their criticism originated in observations made on a revolving shoot which
+is removed from the action of gravity by keeping the plant slowly rotating
+about a horizontal axis by means of the instrument known as a klinostat. 
+Under these conditions circumnutation becomes irregular or ceases
+altogether.  When the same experiment is made with a plant which has twined
+spirally up a stick, the process of climbing is checked and the last few
+turns become loosened or actually untwisted.  From this it has been argued
+that Darwin was wrong in his description of circumnutation as an automatic
+change in the region of quickest growth.  When the free end of a revolving
+shoot points towards the north there is no doubt that the south side has
+been elongating more than the north; after a time it is plain from the
+shoot hanging over to the east that the west side of the plant has grown
+most, and so on.  This rhythmic change of the position of the region of
+greatest growth Darwin ascribes to an unknown internal regulating power. 
+Some modern physiologists, however, attempt to explain the revolving
+movement as due to a particular form of sensitiveness to gravitation which
+it is not necessary to discuss in detail in this place.  It is sufficient
+for my purpose to point out that Darwin's explanation of circumnutation is
+not universally accepted.  Personally I believe that circumnutation is
+automatic--is primarily due to internal stimuli.  It is however in some way
+connected with gravitational sensitiveness, since the movement normally
+occurs round a vertical line.  It is not unnatural that, when the plant has
+no external stimulus by which the vertical can be recognised, the revolving
+movement should be upset.
+
+Very much the same may be said of the act of twining, namely that most
+physiologists refuse to accept Darwin's view (above referred to) that
+twining is the direct result of circumnutation.  Everyone must allow that
+the two phenomena are in some way connected, since a plant which
+circumnutates clockwise, i.e. with the sun, twines in the same direction,
+and vice versa.  It must also be granted that geotropism has a bearing on
+the problem, since all plants twine upwards, and cannot twine along a
+horizontal support.  But how these two factors are combined, and whether
+any (and if so what) other factors contribute, we cannot say.  If we give
+up Darwin's explanation, we must at the same time say with Pfeffer that
+"the causes of twining are...unknown."  ("The Physiology of Plants", Eng.
+Tr. (Oxford, 1906), III. page 37.)
+
+Let us leave this difficult question and consider some other points made
+out in the progress of the work on climbing plants.  One result of what he
+called his "niggling" ("Life and Letters", III. page 312.) work on tendrils
+was the discovery of the delicacy of their sense of touch, and the rapidity
+of their movement.  Thus in a passion-flower tendril, a bit of platinum
+wire weighing 1.2 mg. produced curvature ("Climbing Plants", page 171.), as
+did a loop of cotton weighing 2 mg.  Pfeffer ("Untersuchungen a.d. Bot.
+Inst. z. Tubingen", Bd. I. 1881-85, page 506.), however, subsequently found
+much greater sensitiveness:  thus the tendril of Sicyos angulatus reacted
+to 0.00025 mg., but this only occurred when the delicate rider of
+cottonwool fibre was disturbed by the wind.  The same author expanded and
+explained in a most interesting way the meaning of Darwin's observation
+that tendrils are not stimulated to movement by drops of water resting on
+them.  Pfeffer showed that DIRTY water containing minute particles of clay
+in suspension acts as a stimulus.  He also showed that gelatine acts like
+pure water; if a smooth glass rod is coated with a 10 per cent solution of
+gelatine and is then applied to a tendril, no movement occurs in spite of
+the fact that the gelatine is solid when cold.  Pfeffer ("Physiology", Eng.
+Tr. III. page 52.  Pfeffer has pointed out the resemblance between the
+contact irritability of plants and the human sense of touch.  Our skin is
+not sensitive to uniform pressure such as is produced when the finger is
+dipped into mercury (Tubingen "Untersuchungen", I. page 504.) generalises
+the result in the statement that the tendril has a special form of
+irritability and only reacts to "differences of pressure or variations of
+pressure in contiguous...regions."  Darwin was especially interested in
+such cases of specialised irritability.  For instance in May, 1864, he
+wrote to Asa Gray ("Life and Letters", III. page 314.) describing the
+tendrils of Bignonia capreolata, which "abhor a simple stick, do not much
+relish rough bark, but delight in wool or moss."  He received, from Gray,
+information as to the natural habitat of the species, and finally concluded
+that the tendrils "are specially adapted to climb trees clothed with
+lichens, mosses, or other such productions."  ("Climbing Plants", page
+102.)
+
+Tendrils were not the only instance discovered by Darwin of delicacy of
+touch in plants.  In 1860 he had already begun to observe Sundew (Drosera),
+and was full of astonishment at its behaviour.  He wrote to Sir Joseph
+Hooker ("Life and Letters", III. page 319.):  "I have been working like a
+madman at Drosera.  Here is a fact for you which is certain as you stand
+where you are, though you won't believe it, that a bit of hair 1/78000 of
+one grain in weight placed on gland, will cause ONE of the gland-bearing
+hairs of Drosera to curve inwards."  Here again Pfeffer (Pfeffer in
+"Untersuchungen a. d. Bot. Inst. z. Tubingen", I. page 491.) has, as in so
+many cases, added important facts to my father's observations.  He showed
+that if the leaf of Drosera is entirely freed from such vibrations as would
+reach it if observed on an ordinary table, it does not react to small
+weights, so that in fact it was the vibration of the minute fragment of
+hair on the gland that produced movement.  We may fancifully see an
+adaptation to the capture of insects--to the dancing of a gnat's foot on
+the sensitive surface.
+
+Darwin was fond of telling how when he demonstrated the sensitiveness of
+Drosera to Mr Huxley and (I think) to Sir John Burdon Sanderson, he could
+perceive (in spite of their courtesy) that they thought the whole thing a
+delusion.  And the story ended with his triumph when Mr Huxley cried out,
+"It IS moving."
+
+Darwin's work on tendrils has led to some interesting investigations on the
+mechanisms by which plants perceive stimuli.  Thus Pfeffer (Tubingen
+"Untersuchungen" I. page 524.) showed that certain epidermic cells
+occurring in tendrils are probably organs of touch.  In these cells the
+protoplasm burrows as it were into cavities in the thickness of the
+external cell-walls and thus comes close to the surface, being separated
+from an object touching the tendril merely by a very thin layer of cell-
+wall substance.  Haberlandt ("Physiologische Pflanzenanatomie", Edition
+III. Leipzig, 1904.  "Sinnesorgane im Pflanzenreich", Leipzig, 1901, and
+other publications.) has greatly extended our knowledge of vegetable
+structure in relation to mechanical stimulation.  He defines a sense-organ
+as a contrivance by which the DEFORMATION or forcible change of form in the
+protoplasm--on which mechanical stimulation depends--is rendered rapid and
+considerable in amplitude ("Sinnesorgane", page 10).  He has shown that in
+certain papillose and bristle-like contrivances, plants possess such sense-
+organs; and moreover that these contrivances show a remarkable similarity
+to corresponding sense-organs in animals.
+
+Haberlandt and Nemec ("Ber. d. Deutschen bot. Gesellschaft", XVIII. 1900. 
+See F. Darwin, Presidential Address to Section K, British Association,
+1904.) published independently and simultaneously a theory of the mechanism
+by which plants are orientated in relation to gravitation.  And here again
+we find an arrangement identical in principle with that by which certain
+animals recognise the vertical, namely the pressure of free particles on
+the irritable wall of a cavity.  In the higher plants, Nemec and Haberlandt
+believe that special loose and freely movable starch-grains play the part
+of the otoliths or statoliths of the crustacea, while the protoplasm lining
+the cells in which they are contained corresponds to the sensitive membrane
+lining the otocyst of the animal.  What is of special interest in our
+present connection is that according to this ingenious theory (The original
+conception was due to Noll ("Heterogene Induction", Leipzig, 1892), but his
+view differed in essential points from those here given.) the sense of
+verticality in a plant is a form of contact-irritability.  The vertical
+position is distinguished from the horizontal by the fact that, in the
+latter case, the loose starch-grains rest on the lateral walls of the cells
+instead of on the terminal walls as occurs in the normal upright position. 
+It should be added that the statolith theory is still sub judice;
+personally I cannot doubt that it is in the main a satisfactory explanation
+of the facts.
+
+With regard to the RAPIDITY of the reaction of tendrils, Darwin records
+("Climbing Plants", page 155.  Others have observed movement after about
+6".) that a Passion-Flower tendril moved distinctly within 25 seconds of
+stimulation.  It was this fact, more than any other, that made him doubt
+the current explanation, viz. that the movement is due to unequal growth on
+the two sides of the tendril.  The interesting work of Fitting
+(Pringsheim's "Jahrb." XXXVIII. 1903, page 545.) has shown, however, that
+the primary cause is not (as Darwin supposed) contraction on the concave,
+but an astonishingly rapid increase in growth-rate on the convex side.
+
+On the last page of "Climbing Plants" Darwin wrote:  "It has often been
+vaguely asserted that plants are distinguished from animals by not having
+the power of movement.  It should rather be said that plants acquire and
+display this power only when it is of some advantage to them."
+
+He gradually came to realise the vividness and variety of vegetable life,
+and that a plant like an animal has capacities of behaving in different
+ways under different circumstances, in a manner that may be compared to the
+instinctive movements of animals.  This point of view is expressed in well-
+known passages in the "Power of Movement".  ("The Power of Movement in
+Plants", 1880, pages 571-3.)  "It is impossible not to be struck with the
+resemblance between the...movements of plants and many of the actions
+performed unconsciously by the lower animals."  And again, "It is hardly an
+exaggeration to say that the tip of the radicle...having the power of
+directing the movements of the adjoining parts, acts like the brain of one
+of the lower animals; the brain being seated within the anterior end of the
+body, receiving impressions from the sense-organs, and directing the
+several movements."
+
+The conception of a region of perception distinct from a region of movement
+is perhaps the most fruitful outcome of his work on the movements of
+plants.  But many years before its publication, viz. in 1861, he had made
+out the wonderful fact that in the Orchid Catasetum ("Life and Letters",
+III. page 268.) the projecting organs or antennae are sensitive to a touch,
+and transmit an influence "for more than one inch INSTANTANEOUSLY," which
+leads to the explosion or violent ejection of the pollinia.  And as we have
+already seen a similar transmission of a stimulus was discovered by him in
+Sundew in 1860, so that in 1862 he could write to Hooker ("Life and
+Letters", III. page 321.):  "I cannot avoid the conclusion, that Drosera
+possesses matter at least in some degree analogous in constitution and
+function to nervous matter."  I propose in what follows to give some
+account of the observations on the transmission of stimuli given in the
+"Power of Movement".  It is impossible within the space at my command to
+give anything like a complete account of the matter, and I must necessarily
+omit all mention of much interesting work.  One well-known experiment
+consisted in putting opaque caps on the tips of seedling grasses (e.g. oat
+and canary-grass) and then exposing them to light from one side.  The
+difference, in the amount of curvature towards the light, between the
+blinded and unblinded specimens, was so great that it was concluded that
+the light-sensitiveness resided exclusively in the tip.  The experiment
+undoubtedly proves that the sensitiveness is much greater in the tip than
+elsewhere, and that there is a transmission of stimulus from the tip to the
+region of curvature.  But Rothert (Rothert, Cohn's "Beitrage", VII. 1894.)
+has conclusively proved that the basal part where the curvature occurs is
+also DIRECTLY sensitive to light.  He has shown, however, that in other
+grasses (Setaria, Panicum) the cotyledon is the only part which is
+sensitive, while the hypocotyl, where the movement occurs, is not directly
+sensitive.
+
+It was however the question of the localisation of the gravitational sense
+in the tip of the seedling root or radicle that aroused most attention, and
+it was on this question that a controversy arose which has continued to the
+present day.
+
+The experiment on which Darwin's conclusion was based consisted simply in
+cutting off the tip, and then comparing the behaviour of roots so treated
+with that of normal specimens.  An uninjured root when placed horizontally
+regains the vertical by means of a sharp downward curve; not so a
+decapitated root which continues to grow more or less horizontally.  It was
+argued that this depends on the loss of an organ specialised for the
+perception of gravity, and residing in the tip of the root; and the
+experiment (together with certain important variants) was claimed as
+evidence of the existence of such an organ.
+
+It was at once objected that the amputation of the tip might check
+curvature by interfering with longitudinal growth, on the distribution of
+which curvature depends.  This objection was met by showing that an injury,
+e.g. splitting the root longitudinally (See F. Darwin, "Linnean Soc.
+Journal (Bot)." XIX. 1882, page 218.), which does not remove the tip, but
+seriously checks growth, does not prevent geotropism.  This was of some
+interest in another and more general way, in showing that curvature and
+longitudinal growth must be placed in different categories as regards the
+conditions on which they depend.
+
+Another objection of a much more serious kind was that the amputation of
+the tip acts as a shock.  It was shown by Rothert (See his excellent
+summary of the subject in "Flora" 1894 (Erganzungsband), page 199.) that
+the removal of a small part of the cotyledon of Setaria prevents the plant
+curving towards the light, and here there is no question of removing the
+sense-organ since the greater part of the sensitive cotyledon is intact. 
+In view of this result it was impossible to rely on the amputations
+performed on roots as above described.
+
+At this juncture a new and brilliant method originated in Pfeffer's
+laboratory.  (See Pfeffer, "Annals of Botany", VIII. 1894, page 317, and
+Czapek, Pringsheim's "Jahrb." XXVII. 1895, page 243.)  Pfeffer and Czapek
+showed that it is possible to bend the root of a lupine so that, for
+instance, the supposed sense-organ at the tip is vertical while the motile
+region is horizontal.  If the motile region is directly sensitive to
+gravity the root ought to curve downwards, but this did not occur:  on the
+contrary it continued to grow horizontally.  This is precisely what should
+happen if Darwin's theory is the right one:  for if the tip is kept
+vertical, the sense-organ is in its normal position and receives no
+stimulus from gravitation, and therefore can obviously transmit none to the
+region of curvature.  Unfortunately this method did not convince the
+botanical world because some of those who repeated Czapek's experiment
+failed to get his results.
+
+Czapek ("Berichte d. Deutsch. bot. Ges." XV. 1897, page 516, and numerous
+subsequent papers.  English readers should consult Czapek in the "Annals of
+Botany", XIX. 1905, page 75.) has devised another interesting method which
+throws light on the problem.  He shows that roots, which have been placed
+in a horizontal position and have therefore been geotropically stimulated,
+can be distinguished by a chemical test from vertical, i.e. unstimulated
+roots.  The chemical change in the root can be detected before any
+curvature has occurred and must therefore be a symptom of stimulation, not
+of movement.  It is particularly interesting to find that the change in the
+root, on which Czapek's test depends, takes place in the tip, i.e. in the
+region which Darwin held to be the centre for gravitational sensitiveness.
+
+In 1899 I devised a method (F. Darwin, "Annals of Botany", XIII. 1899, page
+567.) by which I sought to prove that the cotyledon of Setaria is not only
+the organ for light-perception, but also for gravitation.  If a seedling is
+supported horizontally by pushing the apical part (cotyledon) into a
+horizontal tube, the cotyledon will, according to my supposition, be
+stimulated gravitationally and a stimulus will be transmitted to the basal
+part of the stem (hypocotyl) causing it to bend.  But this curvature merely
+raises the basal end of the seedling, the sensitive cotyledon remains
+horizontal, imprisoned in its tube; it will therefore be continually
+stimulated and will continue to transmit influences to the bending region,
+which should therefore curl up into a helix or corkscrew-like form,--and
+this is precisely what occurred.
+
+I have referred to this work principally because the same method was
+applied to roots by Massart (Massart, "Mem. Couronnes Acad. R. Belg." LXII.
+1902.) and myself (F. Darwin, "Linnean Soc. Journ." XXXV. 1902, page 266.)
+with a similar though less striking result.  Although these researches
+confirmed Darwin's work on roots, much stress cannot be laid on them as
+there are several objections to them, and they are not easily repeated.
+
+The method which--as far as we can judge at present--seems likely to solve
+the problem of the root-tip is most ingenious and is due to Piccard. 
+(Pringsheim's "Jahrb." XL. 1904, page 94.)
+
+Andrew Knight's celebrated experiment showed that roots react to
+centrifugal force precisely as they do to gravity.  So that if a bean root
+is fixed to a wheel revolving rapidly on a horizontal axis, it tends to
+curve away from the centre in the line of a radius of the wheel.  In
+ordinary demonstrations of Knight's experiment the seed is generally fixed
+so that the root is at right angles to a radius, and as far as convenient
+from the centre of rotation.  Piccard's experiment is arranged differently. 
+(A seed is depicted below a horizontal dotted line AA, projecting a root
+upwards.)  The root is oblique to the axis of rotation, and the extreme tip
+projects beyond that axis.  Line AA represents the axis of rotation, T is
+the tip of the root just above the line AA, and B is the region just below
+line AA in which curvature takes place.  If the motile region B is directly
+sensitive to gravitation (and is the only part which is sensitive) the root
+will curve (down and away from the vertical) away from the axis of
+rotation, just as in Knight's experiment.  But if the tip T is alone
+sensitive to gravitation the result will be exactly reversed, the stimulus
+originating in T and conveyed to B will produce curvature (up towards the
+vertical).  We may think of the line AA as a plane dividing two worlds.  In
+the lower one gravity is of the earthly type and is shown by bodies falling
+and roots curving downwards:  in the upper world bodies fall upwards and
+roots curve in the same direction.  The seedling is in the lower world, but
+its tip containing the supposed sense-organ is in the strange world where
+roots curve upwards.  By observing whether the root bends up or down we can
+decide whether the impulse to bend originates in the tip or in the motile
+region.
+
+Piccard's results showed that both curvatures occurred and he concluded
+that the sensitive region is not confined to the tip.  (Czapek
+(Pringsheim's "Jahrb." XXXV. 1900, page 362) had previously given reasons
+for believing that, in the root, there is no sharp line of separation
+between the regions of perception and movement.)
+
+Haberlandt (Pringsheim's "Jahrb." XLV. 1908, page 575.) has recently
+repeated the experiment with the advantage of better apparatus and more
+experience in dealing with plants, and has found as Piccard did that both
+the tip and the curving region are sensitive to gravity, but with the
+important addition that the sensitiveness of the tip is much greater than
+that of the motile region.  The case is in fact similar to that of the oat
+and canary-grass.  In both instances my father and I were wrong in assuming
+that the sensitiveness is confined to the tip, yet there is a concentration
+of irritability in that region and transmission of stimulus is as true for
+geotropism as it is for heliotropism.  Thus after nearly thirty years the
+controversy of the root-tip has apparently ended somewhat after the fashion
+of the quarrels at the "Rainbow" in "Silas Marner"--"you're both right and
+you're both wrong."  But the "brain-function" of the root-tip at which
+eminent people laughed in early days turns out to be an important part of
+the truth.  (By using Piccard's method I have succeeded in showing that the
+gravitational sensitiveness of the cotyledon of Sorghum is certainly much
+greater than the sensitiveness of the hypocotyl--if indeed any such
+sensitiveness exists.  See Wiesner's "Festschrift", Vienna, 1908.)
+
+Another observation of Darwin's has given rise to much controversy. 
+("Power of Movement", page 133.)  If a minute piece of card is fixed
+obliquely to the tip of a root some influence is transmitted to the region
+of curvature and the root bends away from the side to which the card was
+attached.  It was thought at the time that this proved the root-tip to be
+sensitive to contact, but this is not necessarily the case.  It seems
+possible that the curvature is a reaction to the injury caused by the
+alcoholic solution of shellac with which the cards were cemented to the
+tip.  This agrees with the fact given in the "Power of Movement" that
+injuring the root-tip on one side, by cutting or burning it, induced a
+similar curvature.  On the other hand it was shown that curvature could be
+produced in roots by cementing cards, not to the naked surface of the root-
+tip, but to pieces of gold-beaters skin applied to the root; gold-beaters
+skin being by itself almost without effect.  But it must be allowed that,
+as regards touch, it is not clear how the addition of shellac and card can
+increase the degree of contact.  There is however some evidence that very
+close contact from a solid body, such as a curved fragment of glass,
+produces curvature:  and this may conceivably be the explanation of the
+effect of gold-beaters skin covered with shellac.  But on the whole it is
+perhaps safer to classify the shellac experiments with the results of
+undoubted injury rather than with those of contact.
+
+Another subject on which a good deal of labour was expended is the sleep of
+leaves, or as Darwin called it their NYCTITROPIC movement.  He showed for
+the first time how widely spread this phenomenon is, and attempted to give
+an explanation of the use to the plant of the power of sleeping.  His
+theory was that by becoming more or less vertical at night the leaves
+escape the chilling effect of radiation.  Our method of testing this view
+was to fix some of the leaves of a sleeping plant so that they remained
+horizontal at night and therefore fully exposed to radiation, while their
+fellows were partly protected by assuming the nocturnal position.  The
+experiments showed clearly that the horizontal leaves were more injured
+than the sleeping, i.e. more or less vertical, ones.  It may be objected
+that the danger from cold is very slight in warm countries where sleeping
+plants abound.  But it is quite possible that a lowering of the temperature
+which produces no visible injury may nevertheless be hurtful by checking
+the nutritive processes (e.g. translocation of carbohydrates), which go on
+at night.  Stahl ("Bot. Zeitung", 1897, page 81.) however has ingeniously
+suggested that the exposure of the leaves to radiation is not DIRECTLY
+hurtful because it lowers the temperature of the leaf, but INDIRECTLY
+because it leads to the deposition of dew on the leaf-surface.  He gives
+reasons for believing that dew-covered leaves are unable to transpire
+efficiently, and that the absorption of mineral food-material is
+correspondingly checked.  Stahl's theory is in no way destructive of
+Darwin's, and it is possible that nyctitropic leaves are adapted to avoid
+the indirect as well as the direct results of cooling by radiation.
+
+In what has been said I have attempted to give an idea of some of the
+discoveries brought before the world in the "Power of Movement" (In 1881
+Professor Wiesner published his "Das Bewegungsvermogen der Pflanzen", a
+book devoted to the criticism of "The Power of Movement in Plants".  A
+letter to Wiesner, published in "Life and Letters", III. page 336, shows
+Darwin's warm appreciation of his critic's work, and of the spirit in which
+it is written.) and of the subsequent history of the problems.  We must now
+pass on to a consideration of the central thesis of the book,--the relation
+of circumnutation to the adaptive curvatures of plants.
+
+Darwin's view is plainly stated on pages 3-4 of the "Power of Movement". 
+Speaking of circumnutation he says, "In this universally present movement
+we have the basis or groundwork for the acquirement, according to the
+requirements of the plant, of the most diversified movements."  He then
+points out that curvatures such as those towards the light or towards the
+centre of the earth can be shown to be exaggerations of circumnutation in
+the given directions.  He finally points out that the difficulty of
+conceiving how the capacities of bending in definite directions were
+acquired is diminished by his conception.  "We know that there is always
+movement in progress, and its amplitude, or direction, or both, have only
+to be modified for the good of the plant in relation with internal or
+external stimuli."
+
+It may at once be allowed that the view here given has not been accepted by
+physiologists.  The bare fact that circumnutation is a general property of
+plants (other than climbing species) is not generally rejected.  But the
+botanical world is no nearer to believing in the theory of reaction built
+on it.
+
+If we compare the movements of plants with those of the lower animals we
+find a certain resemblance between the two.  According to Jennings (H.S.
+Jennings, "The Behavior of the Lower Animals".  Columbia U. Press, N.Y.
+1906.) a Paramoecium constantly tends to swerve towards the aboral side of
+its body owing to certain peculiarities in the set and power of its cilia.
+But the tendency to swim in a circle, thus produced, is neutralised by the
+rotation of the creature about its longitudinal axis.  Thus the direction
+of the swerves IN RELATION TO THE PATH of the organism is always changing,
+with the result that the creature moves in what approximates to a straight
+line, being however actually a spiral about the general line of progress. 
+This method of motion is strikingly like the circumnutation of a plant, the
+apex of which also describes a spiral about the general line of growth.  A
+rooted plant obviously cannot rotate on its axis, but the regular series of
+curvatures of which its growth consists correspond to the aberrations of
+Paramoecium distributed regularly about its course by means of rotation. 
+(In my address to the Biological Section of the British Association at
+Cardiff (1891) I have attempted to show the connection between
+circumnutation and RECTIPETALITY, i.e. the innate capacity of growing in a
+straight line.)  Just as a plant changes its direction of growth by an
+exaggeration of one of the curvature-elements of which circumnutation
+consists, so does a Paramoecium change its course by the accentuation of
+one of the deviations of which its path is built.  Jennings has shown that
+the infusoria, etc., react to stimuli by what is known as the "method of
+trial."  If an organism swims into a region where the temperature is too
+high or where an injurious substance is present, it changes its course.  It
+then moves forward again, and if it is fortunate enough to escape the
+influence, it continues to swim in the given direction.  If however its
+change of direction leads it further into the heated or poisonous region it
+repeats the movement until it emerges from its difficulties.  Jennings
+finds in the movements of the lower organisms an analogue with what is
+known as pain in conscious organisms.  There is certainly this much
+resemblance that a number of quite different sub-injurious agencies produce
+in the lower organisms a form of reaction by the help of which they, in a
+partly fortuitous way, escape from the threatening element in their
+environment.  The higher animals are stimulated in a parallel manner to
+vague and originally purposeless movements, one of which removes the
+discomfort under which they suffer, and the organism finally learns to
+perform the appropriate movement without going through the tentative series
+of actions.
+
+I am tempted to recognise in circumnutation a similar groundwork of
+tentative movements out of which the adaptive ones were originally selected
+by a process rudely representative of learning by experience.
+
+It is, however, simpler to confine ourselves to the assumption that those
+plants have survived which have acquired through unknown causes the power
+of reacting in appropriate ways to the external stimuli of light, gravity,
+etc.  It is quite possible to conceive this occurring in plants which have
+no power of circumnutating--and, as already pointed out, physiologists do
+as a fact neglect circumnutation as a factor in the evolution of movements.
+Whatever may be the fate of Darwin's theory of circumnutation there is no
+doubt that the research he carried out in support of, and by the light of,
+this hypothesis has had a powerful influence in guiding the modern theories
+of the behaviour of plants.  Pfeffer ("The Physiology of Plants", Eng. Tr.
+III. page 11.), who more than any one man has impressed on the world a
+rational view of the reactions of plants, has acknowledged in generous
+words the great value of Darwin's work in the same direction.  The older
+view was that, for instance, curvature towards the light is the direct
+mechanical result of the difference of illumination on the lighted and
+shaded surfaces of the plant.  This has been proved to be an incorrect
+explanation of the fact, and Darwin by his work on the transmission of
+stimuli has greatly contributed to the current belief that stimuli act
+indirectly.  Thus we now believe that in a root and a stem the mechanism
+for the perception of gravitation is identical, but the resulting movements
+are different because the motor-irritabilities are dissimilar in the two
+cases.  We must come back, in fact, to Darwin's comparison of plants to
+animals.  In both there is perceptive machinery by which they are made
+delicately alive to their environment, in both the existing survivors are
+those whose internal constitution has enabled them to respond in a
+beneficial way to the disturbance originating in their sense-organs.
+
+
+XX.  THE BIOLOGY OF FLOWERS.
+
+By K. GOEBEL, Ph.D.
+Professor of Botany in the University of Munich.
+
+There is scarcely any subject to which Darwin devoted so much time and work
+as to his researches into the biology of flowers, or, in other words, to
+the consideration of the question to what extent the structural and
+physiological characters of flowers are correlated with their function of
+producing fruits and seeds.  We know from his own words what fascination
+these studies possessed for him.  We repeatedly find, for example, in his
+letters expressions such as this:--"Nothing in my life has ever interested
+me more than the fertilisation of such plants as Primula and Lythrum, or
+again Anacamptis or Listera."  ("More Letters of Charles Darwin", Vol. II.
+page 419.)
+
+Expressions of this kind coming from a man whose theories exerted an epoch-
+making influence, would be unintelligible if his researches into the
+biology of flowers had been concerned only with records of isolated facts,
+however interesting these might be.  We may at once take it for granted
+that the investigations were undertaken with the view of following up
+important problems of general interest, problems which are briefly dealt
+with in this essay.
+
+Darwin published the results of his researches in several papers and in
+three larger works, (i) "On the various contrivances by which British and
+Foreign Orchids are fertilised by insects" (First edition, London, 1862;
+second edition, 1877; popular edition, 1904.)  (ii)  "The effects of Cross
+and Self fertilisation in the vegetable kingdom" (First edition, 1876;
+second edition, 1878).  (iii)  "The different forms of Flowers on plants of
+the same species" (First edition, 1877; second edition, 1880).
+
+Although the influence of his work is considered later, we may here point
+out that it was almost without a parallel; not only does it include a mass
+of purely scientific observations, but it awakened interest in very wide
+circles, as is shown by the fact that we find the results of Darwin's
+investigations in floral biology universally quoted in school books; they
+are even willingly accepted by those who, as regards other questions, are
+opposed to Darwin's views.
+
+The works which we have mentioned are, however, not only of special
+interest because of the facts they contribute, but because of the MANNER in
+which the facts are expressed.  A superficial reader seeking merely for
+catch-words will, for instance, probably find the book on cross and self-
+fertilisation rather dry because of the numerous details which it contains: 
+it is, indeed, not easy to compress into a few words the general
+conclusions of this volume.  But on closer examination, we cannot be
+sufficiently grateful to the author for the exactness and objectivity with
+which he enables us to participate in the scheme of his researches.  He
+never tries to persuade us, but only to convince us that his conclusions
+are based on facts; he always gives prominence to such facts as appear to
+be in opposition to his opinions,--a feature of his work in accordance with
+a maxim which he laid down:--"It is a golden rule, which I try to follow,
+to put every fact which is opposed to one's preconceived opinion in the
+strongest light."  ("More Letters", Vol. II. page 324.)
+
+The result of this method of presentation is that the works mentioned above
+represent a collection of most valuable documents even for those who feel
+impelled to draw from the data other conclusions than those of the author.
+Each investigation is the outcome of a definite question, a "preconceived
+opinion," which is either supported by the facts or must be abandoned. 
+"How odd it is that anyone should not see that all observation must be for
+or against some view if it is to be of any service!"  (Ibid. Vol. I. page
+195.)
+
+The points of view which Darwin had before him were principally the
+following.  In the first place the proof that a large number of the
+peculiarities in the structure of flowers are not useless, but of the
+greatest significance in pollination must be of considerable importance for
+the interpretation of adaptations; "The use of each trifling detail of
+structure is far from a barren search to those who believe in natural
+selection."  ("Fertilisation of Orchids" (1st edition), page 351; (2nd
+edition 1904) page 286.)  Further, if these structural relations are shown
+to be useful, they may have been acquired because from the many variations
+which have occurred along different lines, those have been preserved by
+natural selection "which are beneficial to the organism under the complex
+and ever-varying conditions of life."  (Ibid. page 351.)  But in the case
+of flowers there is not only the question of adaptation to fertilisation to
+be considered.  Darwin, indeed, soon formed the opinion which he has
+expressed in the following sentence,--"From my own observations on plants,
+guided to a certain extent by the experience of the breeders of animals, I
+became convinced many years ago that it is a general law of nature that
+flowers are adapted to be crossed, at least occasionally, by pollen from a
+distinct plant."  ("Cross and Self fertilisation" (1st edition), page 6.)
+
+The experience of animal breeders pointed to the conclusion that continual
+in-breeding is injurious.  If this is correct, it raises the question
+whether the same conclusion holds for plants.  As most flowers are
+hermaphrodite, plants afford much more favourable material than animals for
+an experimental solution of the question, what results follow from the
+union of nearly related sexual cells as compared with those obtained by the
+introduction of new blood.  The answer to this question must, moreover,
+possess the greatest significance for the correct understanding of sexual
+reproduction in general.
+
+We see, therefore, that the problems which Darwin had before him in his
+researches into the biology of flowers were of the greatest importance, and
+at the same time that the point of view from which he attacked the problems
+was essentially a teleological one.
+
+We may next inquire in what condition he found the biology of flowers at
+the time of his first researches, which were undertaken about the year
+1838.  In his autobiography he writes,--"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 speculations on the origin of species, that crossing
+played an important part in keeping specific forms constant."  ("The Life
+and Letters of Charles Darwin", Vol. I. page 90, London, 1888.)  In 1841 he
+became acquainted with Sprengel's work:  his researches into the biology of
+flowers were thus continued for about forty years.
+
+It is obvious that there could only be a biology of flowers after it had
+been demonstrated that the formation of seeds and fruit in the flower is
+dependent on pollination and subsequent fertilisation.  This proof was
+supplied at the end of the seventeenth century by R.J. Camerarius (1665-
+1721).  He showed that normally seeds and fruits are developed only when
+the pollen reaches the stigma.  The manner in which this happens was first
+thoroughly investigated by J.G. Kolreuter (1733-1806 (Kolreuter,
+"Vorlaufige Nachricht von einigen das Geschlecht der Planzen betreffenden
+Versuchen und Beobachtungen", Leipzig, 1761; with three supplements, 1763-
+66.  Also, "Mem. de l'acad. St Petersbourg", Vol. XV. 1809.)), the same
+observer to whom we owe the earliest experiments in hybridisation of real
+scientific interest. Kolreuter mentioned that pollen may be carried from
+one flower to another partly by wind and partly by insects.  But he held
+the view, and that was, indeed, the natural assumption, that self-
+fertilisation usually occurs in a flower, in other words that the pollen of
+a flower reaches the stigma of the same flower.  He demonstrated, however,
+certain cases in which cross-pollination occurs, that is in which the
+pollen of another flower of the same species is conveyed to the stigma.  He
+was familiar with the phenomenon, exhibited by numerous flowers, to which
+Sprengel afterwards applied the term Dichogamy, expressing the fact that
+the anthers and stigmas of a flower often ripen at different times, a
+peculiarity which is now recognised as one of the commonest means of
+ensuring cross-pollination.
+
+With far greater thoroughness and with astonishing power of observation
+C.K. Sprengel (1750-1816) investigated the conditions of pollination of
+flowers.  Darwin was introduced by that eminent botanist Robert Brown to
+Sprengel's then but little appreciated work,--"Das entdeckte Geheimniss der
+Natur im Bau und in der Befruchtung der Blumen" (Berlin, 1793); this is by
+no means the least service to Botany rendered by Robert Brown.
+
+Sprengel proceeded from a naive teleological point of view.  He firmly
+believed "that the wise Author of nature had not created a single hair
+without a definite purpose."  He succeeded in demonstrating a number of
+beautiful adaptations in flowers for ensuring pollination; but his work
+exercised but little influence on his contemporaries and indeed for a long
+time after his death.  It was through Darwin that Sprengel's work first
+achieved a well deserved though belated fame.  Even such botanists as
+concerned themselves with researches into the biology of flowers appear to
+have formerly attached much less value to Sprengel's work than it has
+received since Darwin's time.  In illustration of this we may quote C.F.
+Gartner whose name is rightly held in the highest esteem as that of one of
+the most eminent hybridologists.  In his work "Versuche und Beobachtungen
+uder die Befruchtungsorgane der vollkommeneren Gewachse und uber die
+naturliche und kunstliche Befruchtung durch den eigenen Pollen" he also
+deals with flower-pollination.  He recognised the action of the wind, but
+he believed, in spite of the fact that he both knew and quoted Kolreuter
+and Sprengel, that while insects assist pollination, they do so only
+occasionally, and he held that insects are responsible for the conveyance
+of pollen; thorough investigations would show "that a very small proportion
+of the plants included in this category require this assistance in their
+native habitat." (Gartner, "Versucher und Beobachtungen...", page 335,
+Stuttgart, 1844.)  In the majority of plants self-pollination occurs.
+
+Seeing that even investigators who had worked for several decades at
+fertilisation-phenomena had not advanced the biology of flowers beyond the
+initial stage, we cannot be surprised that other botanists followed to even
+a less extent the lines laid down by Kolreuter and Sprengel.  This was in
+part the result of Sprengel's supernatural teleology and in part due to the
+fact that his book appeared at a time when other lines of inquiry exerted a
+dominating influence.
+
+At the hands of Linnaeus systematic botany reached a vigorous development,
+and at the beginning of the nineteenth century the anatomy and physiology
+of plants grew from small beginnings to a flourishing branch of science. 
+Those who concerned themselves with flowers endeavoured to investigate
+their development and structure or the most minute phenomena connected with
+fertilisation and the formation of the embryo.  No room was left for the
+extension of the biology of flowers on the lines marked out by Kolreuter
+and Sprengel.  Darwin was the first to give new life and a deeper
+significance to this subject, chiefly because he took as his starting-point
+the above-mentioned problems, the importance of which is at once admitted
+by all naturalists.
+
+The further development of floral biology by Darwin is in the first place
+closely connected with the book on the fertilisation of Orchids.  It is
+noteworthy that the title includes the sentence,--"and on the good effects
+of intercrossing."
+
+The purpose of the book is clearly stated in the introduction:--"The object
+of the following work is to show that the contrivances by which Orchids are
+fertilised, are as varied and almost as perfect as any of the most
+beautiful adaptations in the animal kingdom; and, secondly, to show that
+these contrivances have for their main object the fertilisation of each
+flower by the pollen of another flower."  ("Fertilisation of Orchids", page
+1.)  Orchids constituted a particularly suitable family for such
+researches.  Their flowers exhibit a striking wealth of forms; the
+question, therefore, whether the great variety in floral structure bears
+any relation to fertilisation (In the older botanical literature the word
+fertilisation is usually employed in cases where POLLINATION is really in
+question:  as Darwin used it in this sense it is so used here.) must in
+this case possess special interest.
+
+Darwin succeeded in showing that in most of the orchids examined self-
+fertilisation is either an impossibility, or, under natural conditions,
+occurs only exceptionally.  On the other hand these plants present a series
+of extraordinarily beautiful and remarkable adaptations which ensure the
+transference of pollen by insects from one flower to another.  It is
+impossible to describe adequately in a few words the wealth of facts
+contained in the Orchid book.  A few examples may, however, be quoted in
+illustration of the delicacy of the observations and of the perspicuity
+employed in interpreting the facts.
+
+The majority of orchids differ from other seed plants (with the exception
+of the Asclepiads) in having no dust-like pollen.  The pollen, or more
+correctly, the pollen-tetrads, remain fastened together as club-shaped
+pollinia usually borne on a slender pedicel.  At the base of the pedicel is
+a small viscid disc by which the pollinium is attached to the head or
+proboscis of one of the insects which visit the flower.  Darwin
+demonstrated that in Orchis and other flowers the pedicel of the pollinium,
+after its removal from the anther, undergoes a curving movement.  If the
+pollinium was originally vertical, after a time it assumed a horizontal
+position.  In the latter position, if the insect visited another flower,
+the pollinium would exactly hit the sticky stigmatic surface and thus
+effect fertilisation.  The relation between the behaviour of the viscid
+disc and the secretion of nectar by the flower is especially remarkable. 
+The flowers possess a spur which in some species (e.g. Gymnadenia conopsea,
+Platanthera bifolia, etc.) contains honey (nectar), which serves as an
+attractive bait for insects, but in others (e.g. our native species of
+Orchis) the spur is empty.  Darwin held the opinion, confirmed by later
+investigations, that in the case of flowers without honey the insects must
+penetrate the wall of the nectarless spurs in order to obtain a nectar-like
+substance.  The glands behave differently in the nectar-bearing and in the
+nectarless flowers.  In the former they are so sticky that they at once
+adhere to the body of the insect; in the nectarless flowers firm adherence
+only occurs after the viscid disc has hardened.  It is, therefore,
+adaptively of value that the insects should be detained longer in the
+nectarless flowers (by having to bore into the spur),--than in flowers in
+which the nectar is freely exposed.  "If this relation, on the one hand,
+between the viscid matter requiring some little time to set hard, and the
+nectar being so lodged that moths are delayed in getting it; and, on the
+other hand, between the viscid matter being at first as viscid as ever it
+will become, and the nectar lying all ready for rapid suction, be
+accidental, it is a fortunate accident for the plant.  If not accidental,
+and I cannot believe it to be accidental, what a singular case of
+adaptation!"  ("Fertilisation of Orchids" (1st edition), page 53.)
+
+Among exotic orchids Catasetum is particularly remarkable.  One and the
+same species bears different forms of flowers.  The species known as
+Catasetum tridentatum has pollinia with very large viscid discs; on
+touching one of the two filaments (antennae) which occur on the gynostemium
+of the flower the pollinia are shot out to a fairly long distance (as far
+as 1 metre) and in such manner that they alight on the back of the insect,
+where they are held.  The antennae have, moreover, acquired an importance,
+from the point of view of the physiology of stimulation, as stimulus-
+perceiving organs.  Darwin had shown that it is only a touch on the
+antennae that causes the explosion, while contact, blows, wounding, etc. on
+other places produce no effect.  This form of flower proved to be the male.
+The second form, formerly regarded as a distinct species and named
+Monachanthus viridis, is shown to be the female flower.  The anthers have
+only rudimentary pollinia and do not open; there are no antennae, but on
+the other hand numerous seeds are produced.  Another type of flower, known
+as Myanthus barbatus, was regarded by Darwin as a third form:  this was
+afterwards recognised by Rolfe (Rolfe, R.A. "On the sexual forms of
+Catasetum with special reference to the researches of Darwin and others,"
+"Journ. Linn. Soc." Vol. XXVII. (Botany), 1891, pages 206-225.) as the male
+flower of another species, Catasetum barbatum Link, an identification in
+accordance with the discovery made by Cruger in Trinidad that it always
+remains sterile.
+
+Darwin had noticed that the flowers of Catasetum do not secrete nectar, and
+he conjectured that in place of it the insects gnaw a tissue in the cavity
+of the labellum which has a "slightly sweet, pleasant and nutritious
+taste."  This conjecture as well as other conclusions drawn by Darwin from
+Catasetum have been confirmed by Cruger--assuredly the best proof of the
+acumen with which the wonderful floral structure of this "most remarkable
+of the Orchids" was interpretated far from its native habitat.
+
+As is shown by what we have said about Catasetum, other problems in
+addition to those concerned with fertilisation are dealt with in the Orchid
+book.  This is especially the case in regard to flower morphology.  The
+scope of flower morphology cannot be more clearly and better expressed than
+by these words:  "He will see how curiously a flower may be moulded out of
+many separate organs--how perfect the cohesion of primordially distinct
+parts may become,--how organs may be used for purposes widely different
+from their proper function,--how other organs may be entirely suppressed,
+or leave mere useless emblems of their former existence."  ("Fertilisation
+of Orchids", page 289.)
+
+In attempting, from this point of view, to refer the floral structure of
+orchids to their original form, Darwin employed a much more thorough method
+than that of Robert Brown and others.  The result of this was the
+production of a considerable literature, especially in France, along the
+lines suggested by Darwin's work.  This is the so-called anatomical method,
+which seeks to draw conclusions as to the morphology of the flower from the
+course of the vascular bundles in the several parts.  (He wrote in one of
+his letters, "...the destiny of the whole human race is as nothing to the
+course of vessels of orchids" ("More Letters", Vol. II. page 275.) 
+Although the interpretation of the orchid flower given by Darwin has not
+proved satisfactory in one particular point--the composition of the
+labellum--the general results have received universal assent, namely "that
+all Orchids owe what they have in common to descent from some
+monocotyledonous plant, which, like so many other plants of the same
+division, possessed fifteen organs arranged alternately three within three
+in five whorls."  ("Fertilisation of Orchids" (1st edition), page 307.) 
+The alterations which their original form has undergone have persisted so
+far as they were found to be of use.
+
+We see also that the remarkable adaptations of which we have given some
+examples are directed towards cross-fertilisation.  In only a few of the
+orchids investigated by Darwin--other similar cases have since been
+described--was self-fertilisation found to occur regularly or usually.  The
+former is the case in the Bee Ophrys (Ophrys apifera), the mechanism of
+which greatly surprised Darwin.  He once remarked to a friend that one of
+the things that made him wish to live a few thousand years was his desire
+to see the extinction of the Bee Ophrys, an end to which he believed its
+self-fertilising habit was leading.  ("Life and Letters", Vol. III. page
+276 (footnote).)  But, he wrote, "the safest conclusion, as it seems to me,
+is, that under certain unknown circumstances, and perhaps at very long
+intervals of time, one individual of the Bee Ophrys is crossed by another."
+("Fertilisation of Orchids" page 71.)
+
+If, on the one hand, we remember how much more sure self-fertilisation
+would be than cross-fertilisation, and, on the other hand, if we call to
+mind the numerous contrivances for cross-fertilisation, the conclusion is
+naturally reached that "it is an astonishing fact that self-fertilisation
+should not have been an habitual occurrence.  It apparently demonstrates to
+us that there must be something injurious in the process.  Nature thus
+tells us, in the most emphatic manner, that she abhors perpetual self-
+fertilisation...For may we not further infer as probable, in accordance
+with the belief of the vast majority of the breeders of our domestic
+productions, that marriage between near relations is likewise in some way
+injurious, that some unknown great good is derived from the union of
+individuals which have been kept distinct for many generations?"  (Ibid.,
+page 359.)
+
+This view was supported by observations on plants of other families, e.g.
+Papilionaceae; it could, however, in the absence of experimental proof, be
+regarded only as a "working hypothesis."
+
+All adaptations to cross-pollination might also be of use simply because
+they made pollination possible when for any reason self-pollination had
+become difficult or impossible.  Cross-pollination would, therefore, be of
+use, not as such, but merely as a means of pollination in general; it would
+to some extent serve as a remedy for a method unsuitable in itself, such as
+a modification standing in the way of self-pollination, and on the other
+hand as a means of increasing the chance of pollination in the case of
+flowers in which self-pollination was possible, but which might, in
+accidental circumstances, be prevented.  It was, therefore, very important
+to obtain experimental proof of the conclusion to which Darwin was led by
+the belief of the majority of breeders and by the evidence of the
+widespread occurrence of cross-pollination and of the remarkable
+adaptations thereto.
+
+This was supplied by the researches which are described in the two other
+works named above.  The researches on which the conclusions rest had, in
+part at least, been previously published in separate papers:  this is the
+case as regards the heterostyled plants.  The discoveries which Darwin made
+in the course of his investigations of these plants belong to the most
+brilliant in biological science.
+
+The case of Primula is now well known.  C.K. Sprengel and others were
+familiar with the remarkable fact that different individuals of the
+European species of Primula bear differently constructed flowers; some
+plants possess flowers in which the styles project beyond the stamens
+attached to the corolla-tube (long-styled form), while in others the
+stamens are inserted above the stigma which is borne on a short style
+(short-styled form).  It has been shown by Breitenbach that both forms of
+flower may occur on the same plant, though this happens very rarely.  An
+analogous case is occasionally met with in hybrids, which bear flowers of
+different colour on the same plant (e.g. Dianthus caryophyllus).  Darwin
+showed that the external differences are correlated with others in the
+structure of the stigma and in the nature of the pollen.  The long-styled
+flowers have a spherical stigma provided with large stigmatic papillae; the
+pollen grains are oblong and smaller than those of the short-styled
+flowers.  The number of the seeds produced is smaller and the ovules
+larger, probably also fewer in number.  The short-styled flowers have a
+smooth compressed stigma and a corolla of somewhat different form; they
+produce a greater number of seeds.
+
+These different forms of flowers were regarded as merely a case of
+variation, until Darwin showed "that these heterostyled plants are adapted
+for reciprocal fertilisation; so that the two or three forms, though all
+are hermaphrodites, are related to one another almost like the males and
+females of ordinary unisexual animals."  ("Forms of Flowers" (1st edition),
+page 2.)  We have here an example of hermaphrodite flowers which are
+sexually different.  There are essential differences in the manner in which
+fertilisation occurs.  This may be effected in four different ways; there
+are two legitimate and two illegitimate types of fertilisation.  The
+fertilisation is legitimate if pollen from the long-styled flowers reaches
+the stigma of the short-styled form or if pollen of the short-styled
+flowers is brought to the stigma of the long-styled flower, that is the
+organs of the same length of the two different kinds of flower react on one
+another.  Illegitimate fertilisation is represented by the two kinds of
+self-fertilisation, also by cross-fertilisation, in which the pollen of the
+long-styled form reaches the stigma of the same type of flower and,
+similarly, by cross-pollination in the case of the short-styled flowers.
+
+The applicability of the terms legitimate and illegitimate depends, on the
+one hand, upon the fact that insects which visit the different forms of
+flowers pollinate them in the manner suggested; the pollen of the short-
+styled flowers adhere to that part of the insect's body which touches the
+stigma of the long-styled flower and vice versa.  On the other hand, it is
+based also on the fact that experiment shows that artificial pollination
+produces a very different result according as this is legitimate or
+illegitimate; only the legitimate union ensures complete fertility, the
+plants thus produced being stronger than those which are produced
+illegitimately.
+
+If we take 100 as the number of flowers which produce seeds as the result
+of legitimate fertilisation, we obtain the following numbers from
+illegitimate fertilisation:
+
+Primula officinalis (P. veris) (Cowslip)  ...  69
+Primula elatior (Oxlip)  ....................  27
+Primula acaulis (P. vulgaris) (Primrose)  ...  60
+
+Further, the plants produced by the illegitimate method of fertilisation
+showed, e.g. in P. officinalis, a decrease in fertility in later
+generations, sterile pollen and in the open a feebler growth.  (Under very
+favourable conditions (in a greenhouse) the fertility of the plants of the
+fourth generation increases--a point, which in view of various theoretical
+questions, deserves further investigation.)  They behave in fact precisely
+in the same way as hybrids between species of different genera.  This
+result is important, "for we thus learn that the difficulty in sexually
+uniting two organic forms and the sterility of their offspring, afford no
+sure criterion of so-called specific distinctness" ("Forms of Flowers",
+page 242):  the relative or absolute sterility of the illegitimate unions
+and that of their illegitimate descendants depend exclusively on the nature
+of the sexual elements and on their inability to combine in a particular
+manner.  This functional difference of sexual cells is characteristic of
+the behaviour of hybrids as of the illegitimate unions of heterostyled
+plants.  The agreement becomes even closer if we regard the Primula plants
+bearing different forms of flowers not as belonging to a systematic entity
+or "species," but as including several elementary species.  The
+legitimately produced plants are thus true hybrids (When Darwin wrote in
+reference to the different forms of heterostyled plants, "which all belong
+to the same species as certainly as do the two sexes of the same species"
+("Cross and Self fertilisation", page 466), he adopted the term species in
+a comprehensive sense.  The recent researches of Bateson and Gregory ("On
+the inheritance of Heterostylism in Primula"; "Proc. Roy. Soc." Ser. B,
+Vol. LXXVI. 1905, page 581) appear to me also to support the view that the
+results of illegitimate crossing of heterostyled Primulas correspond with
+those of hybridisation.  The fact that legitimate pollen effects
+fertilisation, even if illegitimate pollen reaches the stigma a short time
+previously, also points to this conclusion.  Self-pollination in the case
+of the short-styled form, for example, is not excluded.  In spite of this,
+the numerical proportion of the two forms obtained in the open remains
+approximately the same as when the pollination was exclusively legitimate,
+presumably because legitimate pollen is prepotent.), with which their
+behaviour in other respects, as Darwin showed, presents so close an
+agreement.  This view receives support also from the fact that descendants
+of a flower fertilised illegitimately by pollen from another plant with the
+same form of flower belong, with few exceptions, to the same type as that
+of their parents.  The two forms of flower, however, behave differently in
+this respect.  Among 162 seedlings of the long-styled illegitimately
+pollinated plants of Primula officinalis, including five generations, there
+were 156 long-styled and only six short-styled forms, while as the result
+of legitimate fertilisation nearly half of the offspring were long-styled
+and half short-styled.  The short-styled illegitimately pollinated form
+gave five long-styled and nine short-styled; the cause of this difference
+requires further explanation.  The significance of heterostyly, whether or
+not we now regard it as an arrangement for the normal production of
+hybrids, is comprehensively expressed by Darwin:  "We may feel sure that
+plants have been rendered heterostyled to ensure cross-fertilisation, for
+we now know that a cross between the distinct individuals of the same
+species is highly important for the vigour and fertility of the offspring." 
+("Forms of Flowers", page 258.)  If we remember how important the
+interpretation of heterostyly has become in all general problems as, for
+example, those connected with the conditions of the formation of hybrids, a
+fact which was formerly overlooked, we can appreciate how Darwin was able
+to say in his autobiography:  "I do not think anything in my scientific
+life has given me so much satisfaction as making out the meaning of the
+structure of these plants."  ("Life and Letters", Vol. I. page 91.)
+
+The remarkable conditions represented in plants with three kinds of
+flowers, such as Lythrum and Oxalis, agree in essentials with those in
+Primula.  These cannot be considered in detail here; it need only be noted
+that the investigation of these cases was still more laborious.  In order
+to establish the relative fertility of the different unions in Lythrum
+salicaria 223 different fertilisations were made, each flower being
+deprived of its male organs and then dusted with the appropriate pollen.
+
+In the book containing the account of heterostyled plants other species are
+dealt with which, in addition to flowers opening normally (chasmogamous),
+also possess flowers which remain closed but are capable of producing
+fruit.  These cleistogamous flowers afford a striking example of habitual
+self-pollination, and H. von Mohl drew special attention to them as such
+shortly after the appearance of Darwin's Orchid book.  If it were only a
+question of producing seed in the simplest way, cleistogamous flowers would
+be the most conveniently constructed.  The corolla and frequently other
+parts of the flower are reduced; the development of the seed may,
+therefore, be accomplished with a smaller expenditure of building material
+than in chasmogamous flowers; there is also no loss of pollen, and thus a
+smaller amount suffices for fertilisation.
+
+Almost all these plants, as Darwin pointed out, have also chasmogamous
+flowers which render cross-fertilisation possible.  His view that
+cleistogamous flowers are derived from originally chasmogamous flowers has
+been confirmed by more recent researches.  Conditions of nutrition in the
+broader sense are the factors which determine whether chasmogamous or
+cleistogamous flowers are produced, assuming, of course, that the plants in
+question have the power of developing both forms of flower.  The former may
+fail to appear for some time, but are eventually developed under favourable
+conditions of nourishment.  The belief of many authors that there are
+plants with only cleistogamous flowers cannot therefore be accepted as
+authoritative without thorough experimental proof, as we are concerned with
+extra-european plants for which it is often difficult to provide
+appropriate conditions in cultivation.
+
+Darwin sees in cleistogamous flowers an adaptation to a good supply of
+seeds with a small expenditure of material, while chasmogamous flowers of
+the same species are usually cross-fertilised and "their offspring will
+thus be invigorated, as we may infer from a wide-spread analogy."  ("Forms
+of Flowers" (1st edition), page 341.)  Direct proof in support of this has
+hitherto been supplied in a few cases only; we shall often find that the
+example set by Darwin in solving such problems as these by laborious
+experiment has unfortunately been little imitated.
+
+Another chapter of this book treats of the distribution of the sexes in
+polygamous, dioecious, and gyno-dioecious plants (the last term, now in
+common use, we owe to Darwin).  It contains a number of important facts and
+discussions and has inspired the experimental researches of Correns and
+others.
+
+The most important of Darwin's work on floral biology is, however, that on
+cross and self-fertilisation, chiefly because it states the results of
+experimental investigations extending over many years.  Only such
+experiments, as we have pointed out, could determine whether cross-
+fertilisation is in itself beneficial, and self-fertilisation on the other
+hand injurious; a conclusion which a merely comparative examination of
+pollination-mechanisms renders in the highest degree probable.  Later
+floral biologists have unfortunately almost entirely confined themselves to
+observations on floral mechanisms.  But there is little more to be gained
+by this kind of work than an assumption long ago made by C.K. Sprengel that
+"very many flowers have the sexes separate and probably at least as many
+hermaphrodite flowers are dichogamous; it would thus appear that Nature was
+unwilling that any flower should be fertilised by its own pollen."
+
+It was an accidental observation which inspired Darwin's experiments on the
+effect of cross and self-fertilisation.  Plants of Linaria vulgaris were
+grown in two adjacent beds; in the one were plants produced by cross-
+fertilisation, that is, from seeds obtained after fertilisation by pollen
+of another plant of the same species; in the other grew plants produced by
+self-fertilisation, that is from seed produced as the result of pollination
+of the same flower.  The first were obviously superior to the latter.
+
+Darwin was surprised by this observation, as he had expected a prejudicial
+influence of self-fertilisation to manifest itself after a series of
+generations:  "I always supposed until lately that no evil effects would be
+visible until after several generations of self-fertilisation, but now I
+see that one generation sometimes suffices and the existence of dimorphic
+plants and all the wonderful contrivances of orchids are quite intelligible
+to me."  ("More Letters", Vol. II. page 373.)
+
+The observations on Linaria and the investigations of the results of
+legitimate and illegitimate fertilisation in heterostyled plants were
+apparently the beginning of a long series of experiments.  These were
+concerned with plants of different families and led to results which are of
+fundamental importance for a true explanation of sexual reproduction.
+
+The experiments were so arranged that plants were shielded from insect-
+visits by a net.  Some flowers were then pollinated with their own pollen,
+others with pollen from another plant of the same species.  The seeds were
+germinated on moist sand; two seedlings of the same age, one from a cross
+and the other from a self-fertilised flower, were selected and planted on
+opposite sides of the same pot.  They grew therefore under identical
+external conditions; it was thus possible to compare their peculiarities
+such as height, weight, fruiting capacity, etc.  In other cases the
+seedlings were placed near to one another in the open and in this way their
+capacity of resisting unfavourable external conditions was tested.  The
+experiments were in some cases continued to the tenth generation and the
+flowers were crossed in different ways.  We see, therefore, that this book
+also represents an enormous amount of most careful and patient original
+work.
+
+The general result obtained is that plants produced as the result of cross-
+fertilisation are superior, in the majority of cases, to those produced as
+the result of self-fertilisation, in height, resistance to external
+injurious influences, and in seed-production.
+
+Ipomoea purpurea may be quoted as an example.  If we express the result of
+cross-fertilisation by 100, we obtain the following numbers for the
+fertilised plants.
+
+Generation.   Height.    Number of seeds.
+
+1             100 : 76   100 : 64
+2             100 : 79   -    
+3             100 : 68   100 : 94
+4             100 : 86   100 : 94
+5             100 : 75   100 : 89
+6             100 : 72   -
+7             100 : 81   -
+8             100 : 85   -
+9             100 : 79   100 : 26 (Number of capsules)
+10            100 : 54   -
+
+Taking the average, the ratio as regards growth is 100:77.  The
+considerable superiority of the crossed plants is apparent in the first
+generation and is not increased in the following generations; but there is
+some fluctuation about the average ratio.  The numbers representing the
+fertility of crossed and self-fertilised plants are more difficult to
+compare with accuracy; the superiority of the crossed plants is chiefly
+explained by the fact that they produce a much larger number of capsules,
+not because there are on the average more seeds in each capsule.  The ratio
+of the capsules was, e.g. in the third generation, 100:38, that of the
+seeds in the capsules 100:94.  It is also especially noteworthy that in the
+self-fertilised plants the anthers were smaller and contained a smaller
+amount of pollen, and in the eighth generation the reduced fertility showed
+itself in a form which is often found in hybrids, that is the first flowers
+were sterile.  (Complete sterility was not found in any of the plants
+investigated by Darwin.  Others appear to be more sensitive; Cluer found
+Zea Mais "almost sterile" after three generations of self-fertilisation.  
+(Cf. Fruwirth, "Die Zuchtung der Landwirtschaftlichen Kulturpflanzen",
+Berlin, 1904, II. page 6.)
+
+The superiority of crossed individuals is not exhibited in the same way in
+all plants.  For example in Eschscholzia californica the crossed seedlings
+do not exceed the self-fertilised in height and vigour, but the crossing
+considerably increases the plant's capacity for flower-production, and the
+seedlings from such a mother-plant are more fertile.
+
+The conception implied by the term crossing requires a closer analysis.  As
+in the majority of plants, a large number of flowers are in bloom at the
+same time on one and the same plant, it follows that insects visiting the
+flowers often carry pollen from one flower to another of the same stock. 
+Has this method, which is spoken of as Geitonogamy, the same influence as
+crossing with pollen from another plant?  The results of Darwin's
+experiments with different plants (Ipomoea purpurea, Digitalis purpurea,
+Mimulus luteus, Pelargonium, Origanum) were not in complete agreement; but
+on the whole they pointed to the conclusion that Geitonogamy shows no
+superiority over self-fertilisation (Autogamy).  (Similarly crossing in the
+case of flowers of Pelargonium zonale, which belong to plants raised from
+cuttings from the same parent, shows no superiority over self-
+fertilisation.)  Darwin, however, considered it possible that this may
+sometimes be the case.  "The sexual elements in the flowers on the same
+plant can rarely have been differentiated, though this is possible, as
+flower-buds are in one sense distinct individuals, sometimes varying and
+differing from one another in structure or constitution."  ("Cross and Self
+fertilisation" (1st edition), page 444.)
+
+As regards the importance of this question from the point of view of the
+significance of cross-fertilisation in general, it may be noted that later
+observers have definitely discovered a difference between the results of
+autogamy and geitonogamy.  Gilley and Fruwirth found that in Brassica
+Napus, the length and weight of the fruits as also the total weight of the
+seeds in a single fruit were less in the case of autogamy than in
+geitonogamy.  With Sinapis alba a better crop of seeds was obtained after
+geitonogamy, and in the Sugar Beet the average weight of a fruit in the
+case of a self-fertilised plant was 0.009 gr., from geitonogamy 0.012 gr.,
+and on cross-fertilisation 0.013 gr.
+
+On the whole, however, the results of geitonogamy show that the favourable
+effects of cross-fertilisation do not depend simply on the fact that the
+pollen of one flower is conveyed to the stigma of another.  But the plants
+which are crossed must in some way be different.  If plants of Ipomoea
+purpurea (and Mimulus luteus) which have been self-fertilised for seven
+generations and grown under the same conditions of cultivation are crossed
+together, the plants so crossed would not be superior to the self-
+fertilised; on the other hand crossing with a fresh stock at once proves
+very advantageous.  The favourable effect of crossing is only apparent,
+therefore, if the parent plants are grown under different conditions or if
+they belong to different varieties.  "It is really wonderful what an effect
+pollen from a distinct seedling plant, which has been exposed to different
+conditions of life, has on the offspring in comparison with pollen from the
+same flower or from a distinct individual, but which has been long
+subjected to the same conditions.  The subject bears on the very principle
+of life, which seems almost to require changes in the conditions."  ("More
+Letters", Vol. II. page 406.)
+
+The fertility--measured by the number or weight of the seeds produced by an
+equal number of plants--noticed under different conditions of fertilisation
+may be quoted in illustration.
+
+                                On crossing   On crossing    On self-
+                                with a fresh  plants of the  fertilisation
+                                stock         same stock
+Mimuleus luteus
+ (First and ninth generation)       100             4              3
+
+Eschscholzia californica
+ (second generation)                100            45             40
+
+Dianthus caryophyllus
+ (third and fourth generation)      100            45             33
+
+Petunia violacea                    100            54             46
+
+Crossing under very similar conditions shows, therefore, that the
+difference between the sexual cells is smaller and thus the result of
+crossing is only slightly superior to that given by self-fertilisation. 
+Is, then, the favourable result of crossing with a foreign stock to be
+attributed to the fact that this belongs to another systematic entity or to
+the fact that the plants, though belonging to the same entity were exposed
+to different conditions?  This is a point on which further researches must
+be taken into account, especially since the analysis of the systematic
+entities has been much more thorough than formerly.  (In the case of garden
+plants, as Darwin to a large extent claimed, it is not easy to say whether
+two individuals really belong to the same variety, as they are usually of
+hybrid origin.  In some instances (Petunia, Iberis) the fresh stock
+employed by Darwin possessed flowers differing in colour from those of the
+plant crossed with it.)  We know that most of Linneaus's species are
+compound species, frequently consisting of a very large number of smaller
+or elementary species formerly included under the comprehensive term
+varieties.  Hybridisation has in most cases affected our garden and
+cultivated plants so that they do not represent pure species but a mixture
+of species.
+
+But this consideration has no essential bearing on Darwin's point of view,
+according to which the nature of the sexual cells is influenced by external
+conditions.  Even individuals growing close to one another are only
+apparently exposed to identical conditions.  Their sexual cells may
+therefore be differently influenced and thus give favourable results on
+crossing, as "the benefits which so generally follow from a cross between
+two plants apparently depend on the two differing somewhat in constitution
+or character."  As a matter of fact we are familiar with a large number of
+cases in which the condition of the reproductive organs is influenced by
+external conditions.  Darwin has himself demonstrated this for self-sterile
+plants, that is plants in which self-fertilisation produces no result. 
+This self-sterility is affected by climatic conditions:  thus in Brazil
+Eschscholzia californica is absolutely sterile to the pollen of its own
+flowers; the descendants of Brazilian plants in Darwin's cultures were
+partially self-fertile in one generation and in a second generation still
+more so.  If one has any doubt in this case whether it is a question of the
+condition of the style and stigma, which possibly prevents the entrance of
+the pollen-tube or even its development, rather than that of the actual
+sexual cells, in other cases there is no doubt that an influence is exerted
+on the latter.
+
+Janczewski (Janczewski, "Sur les antheres steriles des Groseilliers",
+"Bull. de l'acad. des sciences de Cracovie", June, 1908.) has recently
+shown that species of Ribes cultivated under unnatural conditions
+frequently produce a mixed (i.e. partly useless) or completely sterile
+pollen, precisely as happens with hybrids.  There are, therefore,
+substantial reasons for the conclusion that conditions of life exert an
+influence on the sexual cells.  "Thus the proposition that the benefit from
+cross-fertilisation depends on the plants which are crossed having been
+subjected during previous generations to somewhat different conditions, or
+to their having varied from some unknown cause as if they had been thus
+subjected, is securely fortified on all sides."  ("Cross and Self
+fertilisation" (1st edition), page 444.)
+
+We thus obtain an insight into the significance of sexuality.  If an
+occasional and slight alteration in the conditions under which plants and
+animals live is beneficial (Reasons for this are given by Darwin in
+"Variation under Domestication" (2nd edition), Vol. II. page 127.),
+crossing between organisms which have been exposed to different conditions
+becomes still more advantageous.  The entire constitution is in this way
+influenced from the beginning, at a time when the whole organisation is in
+a highly plastic state.  The total life-energy, so to speak, is increased,
+a gain which is not produced by asexual reproduction or by the union of
+sexual cells of plants which have lived under the same or only slightly
+different conditions.  All the wonderful arrangements for cross-
+fertilisation now appear to be useful adaptations.  Darwin was, however,
+far from giving undue prominence to this point of view, though this has
+been to some extent done by others.  He particularly emphasised the
+following consideration:--"But we should always keep in mind that two
+somewhat opposed ends have to be gained; the first and more important one
+being the production of seeds by any means, and the second, cross-
+fertilisation."  ("Cross and Self fertilisation" (1st edition), page 371.) 
+Just as in some orchids and cleistogamic flowers self-pollination regularly
+occurs, so it may also occur in other cases.  Darwin showed that Pisum
+sativum and Lathyrus odoratus belong to plants in which self-pollination is
+regularly effected, and that this accounts for the constancy of certain
+sorts of these plants, while a variety of form is produced by crossing. 
+Indeed among his culture plants were some which derived no benefit from
+crossing.  Thus in the sixth self-fertilised generation of his Ipomoea
+cultures the "Hero" made its appearance, a form slightly exceeding its
+crossed companion in height; this was in the highest degree self-fertile
+and handed on its characteristics to both children and grandchildren. 
+Similar forms were found in Mimulus luteus and Nicotiana (In Pisum sativum
+also the crossing of two individuals of the same variety produced no
+advantage; Darwin attributed this to the fact that the plants had for
+several generations been self-fertilised and in each generation cultivated
+under almost the same conditions.  Tschermak ("Ueber kunstliche Kreuzung an
+Pisum sativum") afterwards recorded the same result; but he found on
+crossing different varieties that usually there was no superiority as
+regards height over the products of self-fertilisation, while Darwin found
+a greater height represented by the ratios 100:75 and 100:60.), types
+which, after self-fertilisation, have an enhanced power of seed-production
+and of attaining a greater height than the plants of the corresponding
+generation which are crossed together and self-fertilised and grown under
+the same conditions.  "Some observations made on other plants lead me to
+suspect that self-fertilisation is in some respects beneficial; although
+the benefit thus derived is as a rule very small compared with that from a
+cross with a distinct plant."  ("Cross and Self fertilisation", page 350.) 
+We are as ignorant of the reason why plants behave differently when crossed
+and self-fertilised as we are in regard to the nature of the
+differentiation of the sexual cells, which determines whether a union of
+the sexual cells will prove favourable or unfavourable.
+
+It is impossible to discuss the different results of cross-fertilisation;
+one point must, however, be emphasised, because Darwin attached
+considerable importance to it.  It is inevitable that pollen of different
+kinds must reach the stigma.  It was known that pollen of the same
+"species" is dominant over the pollen of another species, that, in other
+words, it is prepotent.  Even if the pollen of the same species reaches the
+stigma rather later than that of another species, the latter does not
+effect fertilisation.
+
+Darwin showed that the fertilising power of the pollen of another variety
+or of another individual is greater than that of the plant's own pollen. 
+("Cross and Self fertilisation", page 391.)  This has been demonstrated in
+the case of Mimulus luteus (for the fixed white-flowering variety) and
+Iberis umbellata with pollen of another variety, and observations on
+cultivated plants, such as cabbage, horseradish, etc. gave similar results. 
+It is, however, especially remarkable that pollen of another individual of
+the same variety may be prepotent over the plant's own pollen.  This
+results from the superiority of plants crossed in this manner over self-
+fertilised plants.  "Scarcely any result from my experiments has surprised
+me so much as this of the prepotency of pollen from a distinct individual
+over each plant's own pollen, as proved by the greater constitutional
+vigour of the crossed seedlings."  (Ibid. page 397.)  Similarly, in self-
+fertile plants the flowers of which have not been deprived of the male
+organs, pollen brought to the stigma by the wind or by insects from another
+plant effects fertilisation, even if the plant's own pollen has reached the
+stigma somewhat earlier.
+
+Have the results of his experimental investigations modified the point of
+view from which Darwin entered on his researches, or not?  In the first
+place the question is, whether or not the opinion expressed in the Orchid
+book that there is "Something injurious" connected with self-fertilisation,
+has been confirmed.  We can, at all events, affirm that Darwin adhered in
+essentials to his original position; but self-fertilisation afterwards
+assumed a greater importance than it formerly possessed.  Darwin emphasised
+the fact that "the difference between the self-fertilised and crossed
+plants raised by me cannot be attributed to the superiority of the crossed,
+but to the inferiority of the self-fertilised seedlings, due to the
+injurious effects of self-fertilisation."  (Ibid. page 437.)  But he had no
+doubt that in favourable circumstances self-fertilised plants were able to
+persist for several generations without crossing.  An occasional crossing
+appears to be useful but not indispensable in all cases; its sporadic
+occurrence in plants in which self-pollination habitually occurs is not
+excluded.  Self-fertilisation is for the most part relatively and not
+absolutely injurious and always better than no fertilisation.  "Nature
+abhors perpetual self-fertilisation" (It is incorrect to say, as a writer
+has lately said, that the aphorism expressed by Darwin in 1859 and 1862,
+"Nature abhors perpetual self-fertilisation," is not repeated in his later
+works.  The sentence is repeated in "Cross and Self fertilisation" (page
+8), with the addition, "If the word perpetual had been omitted, the
+aphorism would have been false.  As it stands, I believe that it is true,
+though perhaps rather too strongly expressed.") is, however, a pregnant
+expression of the fact that cross-fertilisation is exceedingly widespread
+and has been shown in the majority of cases to be beneficial, and that in
+those plants in which we find self-pollination regularly occurring cross-
+pollination may occasionally take place.
+
+An attempt has been made to express in brief the main results of Darwin's
+work on the biology of flowers.  We have seen that his object was to
+elucidate important general questions, particularly the question of the
+significance of sexual reproduction.
+
+It remains to consider what influence his work has had on botanical
+science.  That this influence has been very considerable, is shown by a
+glance at the literature on the biology of flowers published since Darwin
+wrote.  Before the book on orchids was published there was nothing but the
+old and almost forgotten works of Kolreuter and Sprengel with the exception
+of a few scattered references.  Darwin's investigations gave the first
+stimulus to the development of an extensive literature on floral biology. 
+In Knuth's "Handbuch der Blutenbiologie" ("Handbook of Flower Pollination",
+Oxford, 1906) as many as 3792 papers on this subject are enumerated as
+having been published before January 1, 1904.  These describe not only the
+different mechanisms of flowers, but deal also with a series of remarkable
+adaptations in the pollinating insects.  As a fertilising rain quickly
+calls into existence the most varied assortment of plants on a barren
+steppe, so activity now reigns in a field which men formerly left deserted. 
+This development of the biology of flowers is of importance not only on
+theoretical grounds but also from a practical point of view.  The rational
+breeding of plants is possible only if the flower-biology of the plants in
+question (i.e. the question of the possibility of self-pollination, self-
+sterility, etc.) is accurately known.  And it is also essential for plant-
+breeders that they should have "the power of fixing each fleeting variety
+of colour, if they will fertilise the flowers of the desired kind with
+their own pollen for half-a-dozen generations, and grow the seedlings under
+the same conditions."  ("Cross and Self fertilisation" (1st edition), page
+460.)
+
+But the influence of Darwin on floral biology was not confined to the
+development of this branch of Botany.  Darwin's activity in this domain has
+brought about (as Asa Gray correctly pointed out) the revival of teleology
+in Botany and Zoology.  Attempts were now made to determine, not only in
+the case of flowers but also in vegetative organs, in what relation the
+form and function of organs stand to one another and to what extent their
+morphological characters exhibit adaptation to environment.  A branch of
+Botany, which has since been called Ecology (not a very happy term) has
+been stimulated to vigorous growth by floral biology.
+
+While the influence of the work on the biology of flowers was
+extraordinarily great, it could not fail to elicit opinions at variance
+with Darwin's conclusions.  The opposition was based partly on reasons
+valueless as counterarguments, partly on problems which have still to be
+solved; to some extent also on that tendency against teleological
+conceptions which has recently become current.  This opposing trend of
+thought is due to the fact that many biologists are content with
+teleological explanations, unsupported by proof; it is also closely
+connected with the fact that many authors estimate the importance of
+natural selection less highly than Darwin did.  We may describe the
+objections which are based on the widespread occurrence of self-
+fertilisation and geitonogamy as of little importance.  Darwin did not deny
+the occurrence of self-fertilisation, even for a long series of
+generations; his law states only that "Nature abhors PERPETUAL self-
+fertilisation."  (It is impossible (as has been attempted) to express
+Darwin's point of view in a single sentence, such as H. Muller's statement
+of the "Knight-Darwin law."  The conditions of life in organisms are so
+various and complex that laws, such as are formulated in physics and
+chemistry, can hardly be conceived.)  An exception to this rule would
+therefore occur only in the case of plants in which the possibility of
+cross-pollination is excluded.  Some of the plants with cleistogamous
+flowers might afford examples of such cases.  We have already seen,
+however, that such a case has not as yet been shown to occur.  Burck
+believed that he had found an instance in certain tropical plants
+(Anonaceae, Myrmecodia) of the complete exclusion of cross-fertilisation. 
+The flowers of these plants, in which, however,--in contrast to the
+cleistogamous flowers--the corolla is well developed, remain closed and
+fruit is produced.
+
+Loew (E. Loew, "Bemerkungen zu Burck...", "Biolog. Centralbl." XXVI.
+(1906).) has shown that cases occur in which cross-fertilisation may be
+effected even in these "cleistopetalous" flowers:  humming birds visit the
+permanently closed flowers of certain species of Nidularium and transport
+the pollen.  The fact that the formation of hybrids may occur as the result
+of this shows that pollination may be accomplished.
+
+The existence of plants for which self-pollination is of greater importance
+than it is for others is by no means contradictory to Darwin's view.  Self-
+fertilisation is, for example, of greater importance for annuals than for
+perennials as without it seeds might fail to be produced.  Even in the case
+of annual plants with small inconspicuous flowers in which self-
+fertilisation usually occurs, such as Senecio vulgaris, Capsella bursa-
+pastoris and Stellaria media, A. Bateson (Anna Bateson, "The effects of
+cross-fertilisation on inconspicuous flowers", "Annals of Botany", Vol. I. 
+1888, page 255.) found that cross-fertilisation gave a beneficial result,
+although only in a slight degree.  If the favourable effects of sexual
+reproduction, according to Darwin's view, are correlated with change of
+environment, it is quite possible that this is of less importance in plants
+which die after ripening their seeds ("hapaxanthic") and which in any case
+constantly change their situation.  Objections which are based on the proof
+of the prevalence of self-fertilisation are not, therefore, pertinent.  At
+first sight another point of view, which has been more recently urged,
+appears to have more weight.
+
+W. Burck (Burck, "Darwin's Kreuzeungsgesetz...", "Biol. Centralbl". XXVIII.
+1908, page 177.) has expressed the opinion that the beneficial results of
+cross-fertilisation demonstrated by Darwin concern only hybrid plants. 
+These alone become weaker by self-pollination; while pure species derive no
+advantage from crossing and no disadvantage from self-fertilisation.  It is
+certain that some of the plants used by Darwin were of hybrid origin.  (It
+is questionable if this was always the case.)  This is evident from his
+statements, which are models of clearness and precision; he says that his
+Ipomoea plants "were probably the offspring of a cross."  ("Cross and Self
+fertilisation" (1st edition), page 55.)  The fixed forms of this plant,
+such as Hero, which was produced by self-fertilisation, and a form of
+Mimulus with white flowers spotted with red probably resulted from
+splitting of the hybrids.  It is true that the phenomena observed in self-
+pollination, e.g. in Ipomoea, agree with those which are often noticed in
+hybrids; Darwin himself drew attention to this.
+
+Let us next call to mind some of the peculiarities connected with
+hybridisation.  We know that hybrids are often characterized by their large
+size, rapidity of growth, earlier production of flowers, wealth of flower-
+production and a longer life; hybrids, if crossed with one of the two
+parent forms, are usually more fertile than when they are crossed together
+or with another hybrid.  But the characters which hybrids exhibit on self-
+fertilisation are rather variable.  The following instance may be quoted
+from Gartner:  "There are many hybrids which retain the self-fertility of
+the first generation during the second and later generations, but very
+often in a less degree; a considerable number, however, become sterile." 
+But the hybrid varieties may be more fertile in the second generation than
+in the first, and in some hybrids the fertility with their own pollen
+increases in the second, third, and following generations.  (K.F. Gartner,
+"Versuche uber die Bastarderzeugung", Stuttgart, 1849, page 149.)  As yet
+it is impossible to lay down rules of general application for the self-
+fertility of hybrids.  That the beneficial influence of crossing with a
+fresh stock rests on the same ground--a union of sexual cells possessing
+somewhat different characters--as the fact that many hybrids are
+distinguished by greater luxuriance, wealth of flowers, etc. corresponds
+entirely with Darwin's conclusions.  It seems to me to follow clearly from
+his investigations that there is no essential difference between cross-
+fertilisation and hybridisation.  The heterostyled plants are normally
+dependent on a process corresponding to hybridisation.  The view that
+specifically distinct species could at best produce sterile hybrids was
+always opposed by Darwin.  But if the good results of crossing were
+EXCLUSIVELY dependent on the fact that we are concerned with hybrids, there
+must then be a demonstration of two distinct things.  First, that crossing
+with a fresh stock belonging to the same systematic entity or to the same
+hybrid, but cultivated for a considerable time under different conditions,
+shows no superiority over self-fertilisation, and that in pure species
+crossing gives no better results than self-pollination.  If this were the
+case, we should be better able to understand why in one plant crossing is
+advantageous while in others, such as Darwin's Hero and the forms of
+Mimulus and Nicotiana no advantage is gained; these would then be pure
+species.  But such a proof has not been supplied; the inference drawn from
+cleistogamous and cleistopetalous plants is not supported by evidence, and
+the experiments on geitonogamy and on the advantage of cross-fertilisation
+in species which are usually self-fertilised are opposed to this view. 
+There are still but few researches on this point; Darwin found that in
+Ononis minutissima, which produces cleistogamous as well as self-fertile
+chasmogamous flowers, the crossed and self-fertilised capsules produced
+seed in the proportion of 100:65 and that the average bore the proportion
+100:86.  Facts previously mentioned are also applicable to this case. 
+Further, it is certain that the self-sterility exhibited by many plants has
+nothing to do with hybridisation.  Between self-sterility and reduced
+fertility as the result of self-fertilisation there is probably no
+fundamental difference.
+
+It is certain that so difficult a problem as that of the significance of
+sexual reproduction requires much more investigation.  Darwin was anything
+but dogmatic and always ready to alter an opinion when it was not based on
+definite proof:  he wrote, "But the veil of secrecy is as yet far from
+lifted; nor will it be, until we can say why it is beneficial that the
+sexual elements should be differentiated to a certain extent, and why, if
+the differentiation be carried still further, injury follows."  He has also
+shown us the way along which to follow up this problem; it is that of
+carefully planned and exact experimental research.  It may be that
+eventually many things will be viewed in a different light, but Darwin's
+investigations will always form the foundation of Floral Biology on which
+the future may continue to build.
+
+
+XXI.  MENTAL FACTORS IN EVOLUTION.
+
+By C. LLOYD MORGAN, LL.D., F.R.S.
+
+In developing his conception of organic evolution Charles Darwin was of
+necessity brought into contact with some of the problems of mental
+evolution.  In "The Origin of Species" he devoted a chapter to "the
+diversities of instinct and of the other mental faculties in animals of the
+same class."  ("Origin of Species" (6th edition), page 205.)  When he
+passed to the detailed consideration of "The Descent of Man", it was part
+of his object to show "that there is no fundamental difference between man
+and the higher mammals in their mental faculties."  ("Descent of Man" (2nd
+edition 1888), Vol. I. page 99; Popular edition page 99.)  "If no organic
+being excepting man," he said, "had possessed any mental power, or if his
+powers had been of a wholly different nature from those of the lower
+animals, then we should never have been able to convince ourselves that our
+high faculties had been gradually developed."  (Ibid. page 99.)  In his
+discussion of "The Expression of the Emotions" it was important for his
+purpose "fully to recognise that actions readily become associated with
+other actions and with various states of the mind."  ("The Expression of
+the Emotions" (2nd edition), page 32.)  His hypothesis of sexual selection
+is largely dependent upon the exercise of choice on the part of the female
+and her preference for "not only the more attractive but at the same time
+the more vigorous and victorious males."  ("Descent of Man", Vol. II. page
+435.)  Mental processes and physiological processes were for Darwin closely
+correlated; and he accepted the conclusion "that the nervous system not
+only regulates most of the existing functions of the body, but has
+indirectly influenced the progressive development of various bodily
+structures and of certain mental qualities."  (Ibid. pages 437, 438.)
+
+Throughout his treatment, mental evolution was for Darwin incidental to and
+contributory to organic evolution.  For specialised research in comparative
+and genetic psychology, as an independent field of investigation, he had
+neither the time nor the requisite training.  None the less his writings
+and the spirit of his work have exercised a profound influence on this
+department of evolutionary thought.  And, for those who follow Darwin's
+lead, mental evolution is still in a measure subservient to organic
+evolution.  Mental processes are the accompaniments or concomitants of the
+functional activity of specially differentiated parts of the organism. 
+They are in some way dependent on physiological and physical conditions. 
+But though they are not physical in their nature, and though it is
+difficult or impossible to conceive that they are physical in their origin,
+they are, for Darwin and his followers, factors in the evolutionary process
+in its physical or organic aspect.  By the physiologist within his special
+and well-defined universe of discourse they may be properly regarded as
+epiphenomena; but by the naturalist in his more catholic survey of nature
+they cannot be so regarded, and were not so regarded by Darwin. 
+Intelligence has contributed to evolution of which it is in a sense a
+product.
+
+The facts of observation or of inference which Darwin accepted are these: 
+Conscious experience accompanies some of the modes of animal behaviour; it
+is concomitant with certain physiological processes; these processes are
+the outcome of development in the individual and evolution in the race; the
+accompanying mental processes undergo a like development.  Into the subtle
+philosophical questions which arise out of the naive acceptance of such a
+creed it was not Darwin's province to enter; "I have nothing to do," he
+said ("Origin of Species" (6th edition), page 205.), "with the origin of
+the mental powers, any more than I have with that of life itself."  He
+dealt with the natural history of organisms, including not only their
+structure but their modes of behaviour; with the natural history of the
+states of consciousness which accompany some of their actions; and with the
+relation of behaviour to experience.  We will endeavour to follow Darwin in
+his modesty and candour in making no pretence to give ultimate
+explanations.  But we must note one of the implications of this self-
+denying ordinance of science.  Development and evolution imply continuity. 
+For Darwin and his followers the continuity is organic through physical
+heredity.  Apart from speculative hypothesis, legitimate enough in its
+proper place but here out of court, we know nothing of continuity of mental
+evolution as such:  consciousness appears afresh in each succeeding
+generation.  Hence it is that for those who follow Darwin's lead, mental
+evolution is and must ever be, within his universe of discourse,
+subservient to organic evolution.  Only in so far as conscious experience,
+or its neural correlate, effects some changes in organic structure can it
+influence the course of heredity; and conversely only in so far as changes
+in organic structure are transmitted through heredity, is mental evolution
+rendered possible.  Such is the logical outcome of Darwin's teaching.
+
+Those who abide by the cardinal results of this teaching are bound to
+regard all behaviour as the expression of the functional activities of the
+living tissues of the organism, and all conscious experience as correlated
+with such activities.  For the purposes of scientific treatment, mental
+processes are one mode of expression of the same changes of which the
+physiological processes accompanying behaviour are another mode of
+expression.  This is simply accepted as a fact which others may seek to
+explain.  The behaviour itself is the adaptive application of the energies
+of the organism; it is called forth by some form of presentation or
+stimulation brought to bear on the organism by the environment.  This
+presentation is always an individual or personal matter.  But in order that
+the organism may be fitted to respond to the presentation of the
+environment it must have undergone in some way a suitable preparation. 
+According to the theory of evolution this preparation is primarily racial
+and is transmitted through heredity.  Darwin's main thesis was that the
+method of preparation is predominantly by natural selection.  Subordinate
+to racial preparation, and always dependent thereon, is individual or
+personal preparation through some kind of acquisition; of which the
+guidance of behaviour through individually won experience is a typical
+example.  We here introduce the mental factor because the facts seem to
+justify the inference.  Thus there are some modes of behaviour which are
+wholly and solely dependent upon inherited racial preparation; there are
+other modes of behaviour which are also dependent, in part at least, on
+individual preparation.  In the former case the behaviour is adaptive on
+the first occurrence of the appropriate presentation; in the latter case
+accommodation to circumstances is only reached after a greater or less
+amount of acquired organic modification of structure, often accompanied (as
+we assume) in the higher animals by acquired experience.  Logically and
+biologically the two classes of behaviour are clearly distinguishable:  but
+the analysis of complex cases of behaviour where the two factors cooperate,
+is difficult and requires careful and critical study of life-history.
+
+The foundations of the mental life are laid in the conscious experience
+that accompanies those modes of behaviour, dependent entirely on racial
+preparation, which may broadly be described as instinctive.  In the eighth
+chapter of "The Origin of Species" Darwin says ("Origin of Species" (6th
+edition), page 205.), "I will not attempt any definition of
+instinct...Every one understands what is meant, when it is said that
+instinct impels the cuckoo to migrate and to lay her eggs in other birds'
+nests.  An action, which we ourselves require experience to enable us to
+perform, when performed by an animal, more especially by a very young one,
+without experience, and when performed by many individuals in the same way,
+without their knowing for what purpose it is performed, is usually said to
+be instinctive."  And in the summary at the close of the chapter he says
+("Origin of Species" (6th edition), page 233.), "I have endeavoured briefly
+to show that the mental qualities of our domestic animals vary, and that
+the variations are inherited.  Still more briefly I have attempted to show
+that instincts vary slightly in a state of nature.  No one will dispute
+that instincts are of the highest importance to each animal.  Therefore
+there is no real difficulty, under changing conditions of life, in natural
+selection accumulating to any extent slight modifications of instinct which
+are in any way useful.  In many cases habit or use and disuse have probably
+come into play."
+
+Into the details of Darwin's treatment there is neither space nor need to
+enter.  There are some ambiguous passages; but it may be said that for him,
+as for his followers to-day, instinctive behaviour is wholly the result of
+racial preparation transmitted through organic heredity.  For the
+performance of the instinctive act no individual preparation under the
+guidance of personal experience is necessary.  It is true that Darwin
+quotes with approval Huber's saying that "a little dose of judgment or
+reason often comes into play, even with animals low in the scale of
+nature."  (Ibid. page 205.)  But we may fairly interpret his meaning to be
+that in behaviour, which is commonly called instinctive, some element of
+intelligent guidance is often combined.  If this be conceded the strictly
+instinctive performance (or part of the performance) is the outcome of
+heredity and due to the direct transmission of parental or ancestral
+aptitudes.  Hence the instinctive response as such depends entirely on how
+the nervous mechanism has been built up through heredity; while intelligent
+behaviour, or the intelligent factor in behaviour, depends also on how the
+nervous mechanism has been modified and moulded by use during its
+development and concurrently with the growth of individual experience in
+the customary situations of daily life.  Of course it is essential to the
+Darwinian thesis that what Sir E. Ray Lankester has termed "educability,"
+not less than instinct, is hereditary.  But it is also essential to the
+understanding of this thesis that the differentiae of the hereditary
+factors should be clearly grasped.
+
+For Darwin there were two modes of racial preparation, (1) natural
+selection, and (2) the establishment of individually acquired habit.  He
+showed that instincts are subject to hereditary variation; he saw that
+instincts are also subject to modification through acquisition in the
+course of individual life.  He believed that not only the variations but
+also, to some extent, the modifications are inherited.  He therefore held
+that some instincts (the greater number) are due to natural selection but
+that others (less numerous) are due, or partly due, to the inheritance of
+acquired habits.  The latter involve Lamarckian inheritance, which of late
+years has been the centre of so much controversy.  It is noteworthy however
+that Darwin laid especial emphasis on the fact that many of the most
+typical and also the most complex instincts--those of neuter insects--do
+not admit of such an interpretation.  "I am surprised," he says ("Origin of
+Species" (6th edition), page 233.), "that no one has hitherto advanced this
+demonstrative case of neuter insects, against the well-known doctrine of
+inherited habit, as advanced by Lamarck."  None the less Darwin admitted
+this doctrine as supplementary to that which was more distinctively his
+own--for example in the case of the instincts of domesticated animals. 
+Still, even in such cases, "it may be doubted," he says (Ibid. pages 210,
+211.), "whether any one would have thought of training a dog to point, had
+not some one dog naturally shown a tendency in this line...so that habit
+and some degree of selection have probably concurred in civilising by
+inheritance our dogs."  But in the interpretation of the instincts of
+domesticated animals, a more recently suggested hypothesis, that of organic
+selection (Independently suggested, on somewhat different lines, by Profs.
+J. Mark Baldwin, Henry F. Osborn and the writer.), may be helpful. 
+According to this hypothesis any intelligent modification of behaviour
+which is subject to selection is probably coincident in direction with an
+inherited tendency to behave in this fashion.  Hence in such behaviour
+there are two factors:  (1) an incipient variation in the line of such
+behaviour, and (2) an acquired modification by which the behaviour is
+carried further along the same line.  Under natural selection those
+organisms in which the two factors cooperate are likely to survive.  Under
+artificial selection they are deliberately chosen out from among the rest.
+
+Organic selection has been termed a compromise between the more strictly
+Darwinian and the Lamarckian principles of interpretation.  But it is not
+in any sense a compromise.  The principle of interpretation of that which
+is instinctive and hereditary is wholly Darwinian.  It is true that some of
+the facts of observation relied upon by Lamarckians are introduced.  For
+Lamarckians however the modifications which are admittedly factors in
+survival, are regarded as the parents of inherited variations; for
+believers in organic selection they are only the foster parents or nurses.
+It is because organic selection is the direct outcome of and a natural
+extension of Darwin's cardinal thesis that some reference to it here is
+justifiable.  The matter may be put with the utmost brevity as follows. 
+(1) Variations (V) occur, some of which are in the direction of increased
+adaptation (+), others in the direction of decreased adaptation (-).  (2)
+Acquired modifications (M) also occur.  Some of these are in the direction
+of increased accommodation to circumstances (+), while others are in the
+direction of diminished accommodation (-).  Four major combinations are 
+
+(a)  + V with + M,
+(b)  + V with - M,
+(c)  - V with + M,
+(d)  - V with - M.
+
+Of these (d) must inevitably be eliminated while (a) are selected.  The
+predominant survival of (a) entails the survival of the adaptive variations
+which are inherited.  The contributory acquisitions (+M) are not inherited;
+but they are none the less factors in determining the survival of the
+coincident variations.  It is surely abundantly clear that this is
+Darwinism and has no tincture of Lamarck's essential principle, the
+inheritance of acquired characters.
+
+Whether Darwin himself would have accepted this interpretation of some at
+least of the evidence put forward by Lamarckians is unfortunately a matter
+of conjecture.  The fact remains that in his interpretation of instinct and
+in allied questions he accepted the inheritance of individually acquired
+modifications of behaviour and structure.
+
+Darwin was chiefly concerned with instinct from the biological rather than
+from the psychological point of view.  Indeed it must be confessed that,
+from the latter standpoint, his conception of instinct as a "mental
+faculty" which "impels" an animal to the performance of certain actions,
+scarcely affords a satisfactory basis for genetic treatment.  To carry out
+the spirit of Darwin's teaching it is necessary to link more closely
+biological and psychological evolution.  The first step towards this is to
+interpret the phenomena of instinctive behaviour in terms of stimulation
+and response.  It may be well to take a particular case.  Swimming on the
+part of a duckling is, from the biological point of view, a typical example
+of instinctive behaviour.  Gently lower a recently hatched bird into water: 
+coordinated movements of the limbs follow in rhythmical sequence.  The
+behaviour is new to the individual though it is no doubt closely related to
+that of walking, which is no less instinctive.  There is a group of stimuli
+afforded by the "presentation" which results from partial immersion:  upon
+this there follows as a complex response an application of the functional
+activities in swimming; the sequence of adaptive application on the
+appropriate presentation is determined by racial preparation.  We know, it
+is true, but little of the physiological details of what takes place in the
+central nervous system; but in broad outline the nature of the organic
+mechanism and the manner of its functioning may at least be provisionally
+conjectured in the present state of physiological knowledge.  Similarly in
+the case of the pecking of newly-hatched chicks; there is a visual
+presentation, there is probably a cooperating group of stimuli from the
+alimentary tract in need of food, there is an adaptive application of the
+activities in a definite mode of behaviour.  Like data are afforded in a
+great number of cases of instinctive procedure, sometimes occurring very
+early in life, not infrequently deferred until the organism is more fully
+developed, but all of them dependent upon racial preparation.  No doubt
+there is some range of variation in the behaviour, just such variation as
+the theory of natural selection demands.  But there can be no question that
+the higher animals inherit a bodily organisation and a nervous system, the
+functional working of which gives rise to those inherited modes of
+behaviour which are termed instinctive.
+
+It is to be noted that the term "instinctive" is here employed in the
+adjectival form as a descriptive heading under which may be grouped many
+and various modes of behaviour due to racial preparation.  We speak of
+these as inherited; but in strictness what is transmitted through heredity
+is the complex of anatomical and physiological conditions under which, in
+appropriate circumstances, the organism so behaves.  So far the term
+"instinctive" has a restricted biological connotation in terms of
+behaviour.  But the connecting link between biological evolution and
+psychological evolution is to be sought,--as Darwin fully realised,--in the
+phenomena of instinct, broadly considered.  The term "instinctive" has also
+a psychological connotation.  What is that connotation?
+
+Let us take the case of the swimming duckling or the pecking chick, and fix
+our attention on the first instinctive performance.  Grant that just as
+there is, strictly speaking, no inherited behaviour, but only the
+conditions which render such behaviour under appropriate circumstances
+possible; so too there is no inherited experience, but only the conditions
+which render such experience possible; then the cerebral conditions in both
+cases are the same.  The biological behaviour-complex, including the total
+stimulation and the total response with the intervening or resultant
+processes in the sensorium, is accompanied by an experience-complex
+including the initial stimulation-consciousness and resulting response-
+consciousness.  In the experience-complex are comprised data which in
+psychological analysis are grouped under the headings of cognition,
+affective tone and conation.  But the complex is probably experienced as an
+unanalysed whole.  If then we use the term "instinctive" so as to comprise
+all congenital modes of behaviour which contribute to experience, we are in
+a position to grasp the view that the net result in consciousness
+constitutes what we may term the primary tissue of experience.  To the
+development of this experience each instinctive act contributes.  The
+nature and manner of organisation of this primary tissue of experience are
+dependent on inherited biological aptitudes; but they are from the outset
+onwards subject to secondary development dependent on acquired aptitudes. 
+Biological values are supplemented by psychological values in terms of
+satisfaction or the reverse.
+
+In our study of instinct we have to select some particular phase of animal
+behaviour and isolate it so far as is possible from the life of which it is
+a part.  But the animal is a going concern, restlessly active in many ways. 
+Many instinctive performances, as Darwin pointed out ("Origin of Species"
+(6th edition), page 206.), are serial in their nature.  But the whole of
+active life is a serial and coordinated business.  The particular
+instinctive performance is only an episode in a life-history, and every
+mode of behaviour is more or less closely correlated with other modes. 
+This coordination of behaviour is accompanied by a correlation of the modes
+of primary experience.  We may classify the instinctive modes of behaviour
+and their accompanying modes of instinctive experience under as many heads
+as may be convenient for our purposes of interpretation, and label them
+instincts of self-preservation, of pugnacity, of acquisition, the
+reproductive instincts, the parental instincts, and so forth.  An instinct,
+in this sense of the term (for example the parental instinct), may be
+described as a specialised part of the primary tissue of experience
+differentiated in relation to some definite biological end.  Under such an
+instinct will fall a large number of particular and often well-defined
+modes of behaviour, each with its own peculiar mode of experience.
+
+It is no doubt exceedingly difficult as a matter of observation and of
+inference securely based thereon to distinguish what is primary from what
+is in part due to secondary acquisition--a fact which Darwin fully
+appreciated.  Animals are educable in different degrees; but where they are
+educable they begin to profit by experience from the first.  Only,
+therefore, on the occasion of the first instinctive act of a given type can
+the experience gained be weighed as WHOLLY primary; all subsequent
+performance is liable to be in some degree, sometimes more, sometimes less,
+modified by the acquired disposition which the initial behaviour engenders. 
+But the early stages of acquisition are always along the lines
+predetermined by instinctive differentiation.  It is the task of
+comparative psychology to distinguish the primary tissue of experience from
+its secondary and acquired modifications.  We cannot follow up the matter
+in further detail.  It must here suffice to suggest that this conception of
+instinct as a primary form of experience lends itself better to natural
+history treatment than Darwin's conception of an impelling force, and that
+it is in line with the main trend of Darwin's thought.
+
+In a characteristic work,--characteristic in wealth of detail, in closeness
+and fidelity of observation, in breadth of outlook, in candour and
+modesty,--Darwin dealt with "The Expression of the Emotions in Man and
+Animals".  Sir Charles Bell in his "Anatomy of Expression" had contended
+that many of man's facial muscles had been specially created for the sole
+purpose of being instrumental in the expression of his emotions.  Darwin
+claimed that a natural explanation, consistent with the doctrine of
+evolution, could in many cases be given and would in other cases be
+afforded by an extension of the principles he advocated.  "No doubt," he
+said ("Expression of the Emotions", page 13.  The passage is here somewhat
+condensed.), "as long as man and all other animals are viewed as
+independent creations, an effectual stop is put to our natural desire to
+investigate as far as possible the causes of Expression.  By this doctrine,
+anything and everything can be equally well explained...With mankind, some
+expressions...can hardly be understood, except on the belief that man once
+existed in a much lower and animal-like condition.  The community of
+certain expressions in distinct though allied species...is rendered
+somewhat more intelligible, if we believe in their descent from a common
+progenitor.  He who admits on general grounds that the structure and habits
+of all animals have been gradually evolved, will look at the whole subject
+of Expression in a new and interesting light."
+
+Darwin relied on three principles of explanation.  "The first of these
+principles is, that movements which are serviceable in gratifying some
+desire, or in relieving some sensation, if often repeated, become so
+habitual that they are performed, whether or not of any service, whenever
+the same desire or sensation is felt, even in a very weak degree."  (Ibid.
+page 368.)  The modes of expression which fall under this head have become
+instinctive through the hereditary transmission of acquired habit.  "As far
+as we can judge, only a few expressive movements are learnt by each
+individual; that is, were consciously and voluntarily performed during the
+early years of life for some definite object, or in imitation of others,
+and then became habitual.  The far greater number of the movements of
+expression, and all the more important ones, are innate or inherited; and
+such cannot be said to depend on the will of the individual.  Nevertheless,
+all those included under our first principle were at first voluntarily
+performed for a definite object,--namely, to escape some danger, to relieve
+some distress, or to gratify some desire."  (Ibid. pages 373, 374.)
+
+"Our second principle is that of antithesis.  The habit of voluntarily
+performing opposite movements under opposite impulses has become firmly
+established in us by the practice of our whole lives.  Hence, if certain
+actions have been regularly performed, in accordance with our first
+principle, under a certain frame of mind, there will be a strong and
+involuntary tendency to the performance of directly opposite actions,
+whether or not these are of any use, under the excitement of an opposite
+frame of mind."  ("Expression of the Emotions", page 368.)  This principle
+of antithesis has not been widely accepted.  Nor is Darwin's own position
+easy to grasp.
+
+"Our third principle," he says (Ibid. page 369.), "is the direct action of
+the excited nervous system on the body, independently of the will, and
+independently, in large part, of habit.  Experience shows that nerve-force
+is generated and set free whenever the cerebro-spinal system is excited. 
+The direction which this nerve-force follows is necessarily determined by
+the lines of connection between the nerve-cells, with each other and with
+various parts of the body."
+
+Lack of space prevents our following up the details of Darwin's treatment
+of expression.  Whether we accept or do not accept his three principles of
+explanation we must regard his work as a masterpiece of descriptive
+analysis, packed full of observations possessing lasting value.  For a
+further development of the subject it is essential that the instinctive
+factors in expression should be more fully distinguished from those which
+are individually acquired--a difficult task--and that the instinctive
+factors should be rediscussed in the light of modern doctrines of heredity,
+with a view to determining whether Lamarckian inheritance, on which Darwin
+so largely relied, is necessary for an interpretation of the facts.
+
+The whole subject as Darwin realised is very complex.  Even the term
+"expression" has a certain amount of ambiguity.  When the emotion is in
+full flood the animal fights, flees, or faints.  Is this full-tide effect
+to be regarded as expression; or are we to restrict the term to the
+premonitory or residual effects--the bared canine when the fighting mood is
+being roused, the ruffled fur when reminiscent representations of the
+object inducing anger cross the mind?  Broadly considered both should be
+included.  The activity of premonitory expression as a means of
+communication was recognised by Darwin; he might, perhaps, have emphasised
+it more strongly in dealing with the lower animals.  Man so largely relies
+on a special means of communication, that of language, that he sometimes
+fails to realise that for animals with their keen powers of perception, and
+dependent as they are on such means of communication, the more strictly
+biological means of expression are full of subtle suggestiveness.  Many
+modes of expression, otherwise useless, are signs of behaviour that may be
+anticipated,--signs which stimulate the appropriate attitude of response. 
+This would not, however, serve to account for the utility of the organic
+accompaniments--heart-affection, respiratory changes, vaso-motor effects
+and so forth, together with heightened muscular tone,--on all of which
+Darwin lays stress ("Expression of the Emotions", pages 65 ff.) under his
+third principle.  The biological value of all this is, however, of great
+importance, though Darwin was hardly in a position to take it fully into
+account.
+
+Having regard to the instinctive and hereditary factors of emotional
+expression we may ask whether Darwin's third principle does not alone
+suffice as an explanation.  Whether we admit or reject Lamarckian
+inheritance it would appear that all hereditary expression must be due to
+pre-established connections within the central nervous system and to a
+transmitted provision for coordinated response under the appropriate
+stimulation.  If this be so, Darwin's first and second principles are
+subordinate and ancillary to the third, an expression, so far as it is
+instinctive or hereditary, being "the direct result of the constitution of
+the nervous system."
+
+Darwin accepted the emotions themselves as hereditary or acquired states of
+mind and devoted his attention to their expression.  But these emotions
+themselves are genetic products and as such dependent on organic
+conditions.  It remained, therefore, for psychologists who accepted
+evolution and sought to build on biological foundations to trace the
+genesis of these modes of animal and human experience.  The subject has
+been independently developed by Professors Lange and James (Cf. William
+James, "Principles of Psychology", Vol. II. Chap. XXV, London, 1890.); and
+some modification of their view is regarded by many evolutionists as
+affording the best explanation of the facts.  We must fix our attention on
+the lower emotions, such as anger or fear, and on their first occurrence in
+the life of the individual organism.  It is a matter of observation that if
+a group of young birds which have been hatched in an incubator are
+frightened by an appropriate presentation, auditory or visual, they
+instinctively respond in special ways.  If we speak of this response as the
+expression, we find that there are many factors.  There are certain visible
+modes of behaviour, crouching at once, scattering and then crouching,
+remaining motionless, the braced muscles sustaining an attitude of arrest,
+and so forth.  There are also certain visceral or organic effects, such as
+affections of the heart and respiration.  These can be readily observed by
+taking the young bird in the hand.  Other effects cannot be readily
+observed; vaso-motor changes, affections of the alimentary canal, the skin
+and so forth.  Now the essence of the James-Lange view, as applied to these
+congenital effects, is that though we are justified in speaking of them as
+effects of the stimulation, we are not justified, without further evidence,
+in speaking of them as effects of the emotional state.  May it not rather
+be that the emotion as a primary mode of experience is the concomitant of
+the net result of the organic situation--the initial presentation, the
+instinctive mode of behaviour, the visceral disturbances?  According to
+this interpretation the primary tissue of experience of the emotional
+order, felt as an unanalysed complex, is generated by the stimulation of
+the sensorium by afferent or incoming physiological impulses from the
+special senses, from the organs concerned in the responsive behaviour, from
+the viscera and vaso-motor system.
+
+Some psychologists, however, contend that the emotional experience is
+generated in the sensorium prior to, and not subsequent to, the behaviour-
+response and the visceral disturbances.  It is a direct and not an indirect
+outcome of the presentation to the special senses.  Be this as it may,
+there is a growing tendency to bring into the closest possible relation, or
+even to identify, instinct and emotion in their primary genesis.  The
+central core of all such interpretations is that instinctive behaviour and
+experience, its emotional accompaniments, and its expression, are but
+different aspects of the outcome of the same organic occurrences.  Such
+emotions are, therefore, only a distinguishable aspect of the primary
+tissue of experience and exhibit a like differentiation.  Here again a
+biological foundation is laid for a psychological doctrine of the mental
+development of the individual.
+
+The intimate relation between emotion as a psychological mode of experience
+and expression as a group of organic conditions has an important bearing on
+biological interpretation.  The emotion, as the psychological accompaniment
+of orderly disturbances in the central nervous system profoundly influences
+behaviour and often renders it more vigorous and more effective.  The
+utility of the emotions in the struggle for existence can, therefore,
+scarcely be over-estimated.  Just as keenness of perception has survival-
+value; just as it is obviously subject to variation; just as it must be
+enhanced under natural selection, whether individually acquired increments
+are inherited or not; and just as its value lies not only in this or that
+special perceptive act but in its importance for life as a whole; so the
+vigorous effectiveness of activity has survival-value; it is subject to
+variation; it must be enhanced under natural selection; and its importance
+lies not only in particular modes of behaviour but in its value for life as
+a whole.  If emotion and its expression as a congenital endowment are but
+different aspects of the same biological occurrence; and if this is a
+powerful supplement to vigour effectiveness and persistency of behaviour,
+it must on Darwin's principles be subject to natural selection.
+
+If we include under the expression of the emotions not only the premonitory
+symptoms of the initial phases of the organic and mental state, not only
+the signs or conditions of half-tide emotion, but the full-tide
+manifestation of an emotion which dominates the situation, we are naturally
+led on to the consideration of many of the phenomena which are discussed
+under the head of sexual selection.  The subject is difficult and complex,
+and it was treated by Darwin with all the strength he could summon to the
+task.  It can only be dealt with here from a special point of view--that
+which may serve to illustrate the influence of certain mental factors on
+the course of evolution.  From this point of view too much stress can
+scarcely be laid on the dominance of emotion during the period of courtship
+and pairing in the more highly organised animals.  It is a period of
+maximum vigour, maximum activity, and, correlated with special modes of
+behaviour and special organic and visceral accompaniments, a period also of
+maximum emotional excitement.  The combats of males, their dances and
+aerial evolutions, their elaborate behaviour and display, or the flood of
+song in birds, are emotional expressions which are at any rate coincident
+in time with sexual periodicity.  From the combat of the males there
+follows on Darwin's principles the elimination of those which are deficient
+in bodily vigour, deficient in special structures, offensive or protective,
+which contribute to success, deficient in the emotional supplement of which
+persistent and whole-hearted fighting is the expression, and deficient in
+alertness and skill which are the outcome of the psychological development
+of the powers of perception.  Few biologists question that we have here a
+mode of selection of much importance, though its influence on psychological
+evolution often fails to receive its due emphasis.  Mr Wallace
+("Darwinism", pages 282, 283, London, 1889.) regards it as "a form of
+natural selection"; "to it," he says, "we must impute the development of
+the exceptional strength, size, and activity of the male, together with the
+possession of special offensive and defensive weapons, and of all other
+characters which arise from the development of these or are correlated with
+them."  So far there is little disagreement among the followers of Darwin--
+for Mr Wallace, with fine magnanimity, has always preferred to be ranked as
+such, notwithstanding his right, on which a smaller man would have
+constantly insisted, to the claim of independent originator of the doctrine
+of natural selection.  So far with regard to sexual selection Darwin and Mr
+Wallace are agreed; so far and no farther.  For Darwin, says Mr Wallace
+(Ibid. page 283.), "has extended the principle into a totally different
+field of action, which has none of that character of constancy and of
+inevitable result that attaches to natural selection, including male
+rivalry; for by far the larger portion of the phenomena, which he
+endeavours to explain by the direct action of sexual selection, can only be
+so explained on the hypothesis that the immediate agency is female choice
+or preference.  It is to this that he imputes the origin of all secondary
+sexual characters other than weapons of offence and defence...In this
+extension of sexual selection to include the action of female choice or
+preference, and in the attempt to give to that choice such wide-reaching
+effects, I am unable to follow him more than a very little way."
+
+Into the details of Mr Wallace's criticisms it is impossible to enter here.
+We cannot discuss either the mode of origin of the variations in structure
+which have rendered secondary sexual characters possible or the modes of
+selection other than sexual which have rendered them, within narrow limits,
+specifically constant.  Mendelism and mutation theories may have something
+to say on the subject when these theories have been more fully correlated
+with the basal principles of selection.  It is noteworthy that Mr Wallace
+says ("Darwinism", pages 283, 284.):  "Besides the acquisition of weapons
+by the male for the purpose of fighting with other males, there are some
+other sexual characters which may have been produced by natural selection.
+Such are the various sounds and odours which are peculiar to the male, and
+which serve as a call to the female or as an indication of his presence. 
+These are evidently a valuable addition to the means of recognition of the
+two sexes, and are a further indication that the pairing season has
+arrived; and the production, intensification, and differentiation of these
+sounds and odours are clearly within the power of natural selection.  The
+same remark will apply to the peculiar calls of birds, and even to the
+singing of the males."  Why the same remark should not apply to their
+colours and adornments is not obvious.  What is obvious is that "means of
+recognition" and "indication that the pairing season has arrived" are
+dependent on the perceptive powers of the female who recognises and for
+whom the indication has meaning.  The hypothesis of female preference,
+stripped of the aesthetic surplusage which is psychologically both
+unnecessary and unproven, is really only different in degree from that
+which Mr Wallace admits in principle when he says that it is probable that
+the female is pleased or excited by the display.
+
+Let us for our present purpose leave on one side and regard as sub judice
+the question whether the specific details of secondary sexual characters
+are the outcome of female choice.  For us the question is whether certain
+psychological accompaniments of the pairing situation have influenced the
+course of evolution and whether these psychological accompaniments are
+themselves the outcome of evolution.  As a matter of observation, specially
+differentiated modes of behaviour, often very elaborate, frequently
+requiring highly developed skill, and apparently highly charged with
+emotional tone, are the precursors of pairing.  They are generally confined
+to the males, whose fierce combats during the period of sexual activity are
+part of the emotional manifestation.  It is inconceivable that they have no
+biological meaning; and it is difficult to conceive that they have any
+other biological end than to evoke in the generally more passive female the
+pairing impulse.  They are based on instinctive foundations ingrained in
+the nervous constitution through natural (or may we not say sexual?)
+selection in virtue of their profound utility.  They are called into play
+by a specialised presentation such as the sight or the scent of the female
+at, or a little in advance of, a critical period of the physiological
+rhythm.  There is no necessity that the male should have any knowledge of
+the end to which his strenuous activity leads up.  In presence of the
+female there is an elaborate application of all the energies of behaviour,
+just because ages of racial preparation have made him biologically and
+emotionally what he is--a functionally sexual male that must dance or sing
+or go through hereditary movements of display, when the appropriate
+stimulation comes.  Of course after the first successful courtship his
+future behaviour will be in some degree modified by his previous
+experience.  No doubt during his first courtship he is gaining the primary
+data of a peculiarly rich experience, instinctive and emotional.  But the
+biological foundations of the behaviour of courtship are laid in the
+hereditary coordinations.  It would seem that in some cases, not indeed in
+all, but perhaps especially in those cases in which secondary sexual
+behaviour is most highly evolved,--correlative with the ardour of the male
+is a certain amount of reluctance in the female.  The pairing act on her
+part only takes place after prolonged stimulation, for affording which the
+behaviour of male courtship is the requisite presentation.  The most
+vigorous, defiant and mettlesome male is preferred just because he alone
+affords a contributory stimulation adequate to evoke the pairing impulse
+with its attendant emotional tone.
+
+It is true that this places female preference or choice on a much lower
+psychological plane than Darwin in some passages seems to contemplate
+where, for example, he says that the female appreciates the display of the
+male and places to her credit a taste for the beautiful.  But Darwin
+himself distinctly states ("Descent of Man" (2nd edition), Vol. II. pages
+136, 137; (Popular edition), pages 642, 643.) that "it is not probable that
+she consciously deliberates; but she is most excited or attracted by the
+most beautiful, or melodious, or gallant males."  The view here put
+forward, which has been developed by Prof. Groos ("The Play of Animals",
+page 244, London, 1898.), therefore seems to have Darwin's own sanction. 
+The phenomena are not only biological; there are psychological elements as
+well.  One can hardly suppose that the female is unconscious of the male's
+presence; the final yielding must surely be accompanied by heightened
+emotional tone.  Whether we call it choice or not is merely a matter of
+definition of terms.  The behaviour is in part determined by supplementary
+psychological values.  Prof. Groos regards the coyness of females as "a
+most efficient means of preventing the too early and too frequent yielding
+to the sexual impulse."  (Ibid. page 283.)  Be that as it may, it is, in
+any case, if we grant the facts, a means through which male sexual
+behaviour with all its biological and psychological implications, is raised
+to a level otherwise perhaps unattainable by natural means, while in the
+female it affords opportunities for the development in the individual and
+evolution in the race of what we may follow Darwin in calling appreciation,
+if we empty this word of the aesthetic implications which have gathered
+round it in the mental life of man.
+
+Regarded from this standpoint sexual selection, broadly considered, has
+probably been of great importance.  The psychological accompaniments of the
+pairing situation have profoundly influenced the course of biological
+evolution and are themselves the outcome of that evolution.
+
+Darwin makes only passing reference to those modes of behaviour in animals
+which go by the name of play.  "Nothing," he says ("Descent of Man", Vol.
+II. page 60; (Popular edition), page 566.), "is more common than for
+animals to take pleasure in practising whatever instinct they follow at
+other times for some real good."  This is one of the very numerous cases in
+which a hint of the master has served to stimulate research in his
+disciples.  It was left to Prof. Groos to develop this subject on
+evolutionary lines and to elaborate in a masterly manner Darwin's
+suggestion.  "The utility of play," he says ("The Play of Animals", page
+76.), "is incalculable.  This utility consists in the practice and exercise
+it affords for some of the more important duties of life,"--that is to say,
+for the performance of activities which will in adult life be essential to
+survival.  He urges (Ibid. page 75.) that "the play of young animals has
+its origin in the fact that certain very important instincts appear at a
+time when the animal does not seriously need them."  It is, however,
+questionable whether any instincts appear at a time when they are not
+needed.  And it is questionable whether the instinctive and emotional
+attitude of the play-fight, to take one example, can be identified with
+those which accompany fighting in earnest, though no doubt they are closely
+related and have some common factors.  It is probable that play, as
+preparatory behaviour, differs in biological detail (as it almost certainly
+does in emotional attributes) from the earnest of after-life and that it
+has been evolved through differentiation and integration of the primary
+tissue of experience, as a preparation through which certain essential
+modes of skill may be acquired--those animals in which the preparatory
+play-propensity was not inherited in due force and requisite amount being
+subsequently eliminated in the struggle for existence.  In any case there
+is little question that Prof. Groos is right in basing the play-propensity
+on instinctive foundations.  ("The Play of Animals" page 24.)  None the
+less, as he contends, the essential biological value of play is that it is
+a means of training the educable nerve-tissue, of developing that part of
+the brain which is modified by experience and which thus acquires new
+characters, of elaborating the secondary tissue of experience on the
+predetermined lines of instinctive differentiation and thus furthering the
+psychological activities which are included under the comprehensive term
+"intelligent."
+
+In "The Descent of Man" Darwin dealt at some length with intelligence and
+the higher mental faculties.  ("Descent of Man" (1st edition), Chapters II,
+III, V; (2nd edition), Chapters III, IV, V.)  His object, he says, is to
+show that there is no fundamental difference between man and the higher
+mammals in their mental faculties; that these faculties are variable and
+the variations tend to be inherited; and that under natural selection
+beneficial variations of all kinds will have been preserved and injurious
+ones eliminated.
+
+Darwin was too good an observer and too honest a man to minimise the
+"enormous difference" between the level of mental attainment of civilised
+man and that reached by any animal.  His contention was that the
+difference, great as it is, is one of degree and not of kind.  He realised
+that, in the development of the mental faculties of man, new factors in
+evolution have supervened--factors which play but a subordinate and
+subsidiary part in animal intelligence.  Intercommunication by means of
+language, approbation and blame, and all that arises out of reflective
+thought, are but foreshadowed in the mental life of animals.  Still he
+contends that these may be explained on the doctrine of evolution.  He
+urges (Ibid. Vol. I. pages 70, 71; (Popular edition), pages 70, 71.)" that
+man is variable in body and mind; and that the variations are induced,
+either directly or indirectly, by the same general causes, and obey the
+same general laws, as with the lower animals."  He correlates mental
+development with the evolution of the brain.  (Ibid. page 81.)  "As the
+various mental faculties gradually developed themselves, the brain would
+almost certainly become larger.  No one, I presume, doubts that the large
+proportion which the size of man's brain bears to his body, compared to the
+same proportion in the gorilla or orang, is closely connected with his
+higher mental powers."  "With respect to the lower animals," he says
+("Descent of Man" (Popular edition), page 82.), "M.E. Lartet ("Comptes
+Rendus des Sciences", June 1, 1868.), by comparing the crania of tertiary
+and recent mammals belonging to the same groups, has come to the remarkable
+conclusion that the brain is generally larger and the convolutions are more
+complex in the more recent form."
+
+Sir E. Ray Lankester has sought to express in the simplest terms the
+implications of the increase in size of the cerebrum.  "In what," he asks,
+"does the advantage of a larger cerebral mass consist?"  "Man," he replies
+"is born with fewer ready-made tricks of the nerve-centres--these
+performances of an inherited nervous mechanism so often called by the ill-
+defined term 'instincts'--than are the monkeys or any other animal. 
+Correlated with the absence of inherited ready-made mechanism, man has a
+greater capacity of developing in the course of his individual growth
+similar nervous mechanisms (similar to but not identical with those of
+'instinct') than any other animal...The power of being educated--
+'educability' as we may term it--is what man possesses in excess as
+compared with the apes.  I think we are justified in forming the hypothesis
+that it is this 'educability' which is the correlative of the increased
+size of the cerebrum."  There has been natural selection of the more
+educable animals, for "the character which we describe as 'educability' can
+be transmitted, it is a congenital character.  But the RESULTS of education
+can NOT be transmitted.  In each generation they have to be acquired
+afresh, and with increased 'educability' they are more readily acquired and
+a larger variety of them...The fact is that there is no community between
+the mechanisms of instinct and the mechanisms of intelligence, and that the
+latter are later in the history of the evolution of the brain than the
+former and can only develop in proportion as the former become feeble and
+defective."  ("Nature", Vol. LXI. pages 624, 625 (1900).)
+
+In this statement we have a good example of the further development of
+views which Darwin foreshadowed but did not thoroughly work out.  It states
+the biological case clearly and tersely.  Plasticity of behaviour in
+special accommodation to special circumstances is of survival value; it
+depends upon acquired characters; it is correlated with increase in size
+and complexity of the cerebrum; under natural selection therefore the
+larger and more complex cerebrum as the organ of plastic behaviour has been
+the outcome of natural selection.  We have thus the biological foundations
+for a further development of genetic psychology.
+
+There are diversities of opinion, as Darwin showed, with regard to the
+range of instinct in man and the higher animals as contrasted with lower
+types.  Darwin himself said ("Descent of Man", Vol. I. page 100.) that
+"Man, perhaps, has somewhat fewer instincts than those possessed by the
+animals which come next to him in the series."  On the other hand, Prof.
+Wm. James says ("Principles of Psychology," Vol. II. page 289.) that man is
+probably the animal with most instincts.  The true position is that man and
+the higher animals have fewer complete and self-sufficing instincts than
+those which stand lower in the scale of mental evolution, but that they
+have an equally large or perhaps larger mass of instinctive raw material
+which may furnish the stuff to be elaborated by intelligent processes. 
+There is, perhaps, a greater abundance of the primary tissue of experience
+to be refashioned and integrated by secondary modification; there is
+probably the same differentiation in relation to the determining biological
+ends, but there is at the outset less differentiation of the particular and
+specific modes of behaviour.  The specialised instinctive performances and
+their concomitant experience-complexes are at the outset more indefinite. 
+Only through acquired connections, correlated with experience, do they
+become definitely organised.
+
+The full working-out of the delicate and subtle relationship of instinct
+and educability--that is, of the hereditary and the acquired factors in the
+mental life--is the task which lies before genetic and comparative
+psychology.  They interact throughout the whole of life, and their
+interactions are very complex.  No one can read the chapters of "The
+Descent of Man" which Darwin devotes to a consideration of the mental
+characters of man and animals without noticing, on the one hand, how
+sedulous he is in his search for hereditary foundations, and, on the other
+hand, how fully he realises the importance of acquired habits of mind.  The
+fact that educability itself has innate tendencies--is in fact a partially
+differentiated educability--renders the unravelling of the factors of
+mental progress all the more difficult.
+
+In his comparison of the mental powers of men and animals it was essential
+that Darwin should lay stress on points of similarity rather than on points
+of difference.  Seeking to establish a doctrine of evolution, with its
+basal concept of continuity of process and community of character, he was
+bound to render clear and to emphasise the contention that the difference
+in mind between man and the higher animals, great as it is, is one of
+degree and not of kind.  To this end Darwin not only recorded a large
+number of valuable observations of his own, and collected a considerable
+body of information from reliable sources, he presented the whole subject
+in a new light and showed that a natural history of mind might be written
+and that this method of study offered a wide and rich field for
+investigation.  Of course those who regarded the study of mind only as a
+branch of metaphysics smiled at the philosophical ineptitude of the mere
+man of science.  But the investigation, on natural history lines, has been
+prosecuted with a large measure of success.  Much indeed still remains to
+be done; for special training is required, and the workers are still few. 
+Promise for the future is however afforded by the fact that investigation
+is prosecuted on experimental lines and that something like organised
+methods of research are taking form.  There is now but little reliance on
+casual observations recorded by those who have not undergone the necessary
+discipline in these methods.  There is also some change of emphasis in
+formulating conclusions.  Now that the general evolutionary thesis is fully
+and freely accepted by those who carry on such researches, more stress is
+laid on the differentiation of the stages of evolutionary advance than on
+the fact of their underlying community of nature.  The conceptual
+intelligence which is especially characteristic of the higher mental
+procedure of man is more firmly distinguished from the perceptual
+intelligence which he shares with the lower animals--distinguished now as a
+higher product of evolution, no longer as differing in origin or different
+in kind.  Some progress has been made, on the one hand in rendering an
+account of intelligent profiting by experience under the guidance of
+pleasure and pain in the perceptual field, on lines predetermined by
+instinctive differentiation for biological ends, and on the other hand in
+elucidating the method of conceptual thought employed, for example, by the
+investigator himself in interpreting the perceptual experience of the lower
+animals.
+
+Thus there is a growing tendency to realise more fully that there are two
+orders of educability--first an educability of the perceptual intelligence
+based on the biological foundation of instinct, and secondly an educability
+of the conceptual intelligence which refashions and rearranges the data
+afforded by previous inheritance and acquisition.  It is in relation to
+this second and higher order of educability that the cerebrum of man shows
+so large an increase of mass and a yet larger increase of effective surface
+through its rich convolutions.  It is through educability of this order
+that the human child is brought intellectually and affectively into touch
+with the ideal constructions by means of which man has endeavoured, with
+more or less success, to reach an interpretation of nature, and to guide
+the course of the further evolution of his race--ideal constructions which
+form part of man's environment.
+
+It formed no part of Darwin's purpose to consider, save in broad outline,
+the methods, or to discuss in any fulness of detail the results of the
+process by which a differentiation of the mental faculties of man from
+those of the lower animals has been brought about--a differentiation the
+existence of which he again and again acknowledges.  His purpose was rather
+to show that, notwithstanding this differentiation, there is basal
+community in kind.  This must be remembered in considering his treatment of
+the biological foundations on which man's systems of ethics are built.  He
+definitely stated that he approached the subject "exclusively from the side
+of natural history."  ("Descent of Man", Vol. I. page 149.)  His general
+conclusion is that the moral sense is fundamentally identical with the
+social instincts, which have been developed for the good of the community;
+and he suggests that the concept which thus enables us to interpret the
+biological ground-plan of morals also enables us to frame a rational ideal
+of the moral end.  "As the social instincts," he says (Ibid. page 185.),
+"both of man and the lower animals have no doubt been developed by nearly
+the same steps, it would be advisable, if found practicable, to use the
+same definition in both cases, and to take as the standard of morality, the
+general good or welfare of the community, rather than the general
+happiness."  But the kind of community for the good of which the social
+instincts of animals and primitive men were biologically developed may be
+different from that which is the product of civilisation, as Darwin no
+doubt realised.  Darwin's contention was that conscience is a social
+instinct and has been evolved because it is useful to the tribe in the
+struggle for existence against other tribes.  On the other hand, J.S. Mill
+urged that the moral feelings are not innate but acquired, and Bain held
+the same view, believing that the moral sense is acquired by each
+individual during his life-time.  Darwin, who notes (Ibid. page 150
+(footnote).) their opinion with his usual candour, adds that "on the
+general theory of evolution this is at least extremely improbable.  It is
+impossible to enter into the question here:  much turns on the exact
+connotation of the terms "conscience" and "moral sense," and on the meaning
+we attach to the statement that the moral sense is fundamentally identical
+with the social instincts.
+
+Presumably the majority of those who approach the subjects discussed in the
+third, fourth and fifth chapters of "The Descent of Man" in the full
+conviction that mental phenomena, not less than organic phenomena, have a
+natural genesis, would, without hesitation, admit that the intellectual and
+moral systems of civilised man are ideal constructions, the products of
+conceptual thought, and that as such they are, in their developed form,
+acquired.  The moral sentiments are the emotional analogues of highly
+developed concepts.  This does not however imply that they are outside the
+range of natural history treatment.  Even though it may be desirable to
+differentiate the moral conduct of men from the social behaviour of animals
+(to which some such term as "pre-moral" or "quasi-moral" may be applied),
+still the fact remains that, as Darwin showed, there is abundant evidence
+of the occurrence of such social behaviour--social behaviour which, even
+granted that it is in large part intelligently acquired, and is itself so
+far a product of educability, is of survival value.  It makes for that
+integration without which no social group could hold together and escape
+elimination.  Furthermore, even if we grant that such behaviour is
+intelligently acquired, that is to say arises through the modification of
+hereditary instincts and emotions, the fact remains that only through these
+instinctive and emotional data is afforded the primary tissue of the
+experience which is susceptible of such modification.
+
+Darwin sought to show, and succeeded in showing, that for the intellectual
+and moral life there are instinctive foundations which a biological
+treatment alone can disclose.  It is true that he did not in all cases
+analytically distinguish the foundations from the superstructure.  Even to-
+day we are scarcely in a position to do so adequately.  But his treatment
+was of great value in giving an impetus to further research.  This value
+indeed can scarcely be overestimated.  And when the natural history of the
+mental operations shall have been written, the cardinal fact will stand
+forth, that the instinctive and emotional foundations are the outcome of
+biological evolution and have been ingrained in the race through natural
+selection.  We shall more clearly realise that educability itself is a
+product of natural selection, though the specific results acquired through
+cerebral modifications are not transmitted through heredity.  It will,
+perhaps, also be realised that the instinctive foundations of social
+behaviour are, for us, somewhat out of date and have undergone but little
+change throughout the progress of civilisation, because natural selection
+has long since ceased to be the dominant factor in human progress.  The
+history of human progress has been mainly the history of man's higher
+educability, the products of which he has projected on to his environment. 
+This educability remains on the average what it was a dozen generations
+ago; but the thought-woven tapestry of his surroundings is refashioned and
+improved by each succeeding generation.  Few men have in greater measure
+enriched the thought-environment with which it is the aim of education to
+bring educable human beings into vital contact, than has Charles Darwin. 
+His special field of work was the wide province of biology; but he did much
+to help us realise that mental factors have contributed to organic
+evolution and that in man, the highest product of Evolution, they have
+reached a position of unquestioned supremacy.
+
+
+XXII.  THE INFLUENCE OF THE CONCEPTION OF EVOLUTION ON MODERN PHILOSOPHY.
+
+By H. HOFFDING.
+Professor of Philosophy in the University of Copenhagen.
+
+I.
+
+It is difficult to draw a sharp line between philosophy and natural
+science.  The naturalist who introduces a new principle, or demonstrates a
+fact which throws a new light on existence, not only renders an important
+service to philosophy but is himself a philosopher in the broader sense of
+the word.  The aim of philosophy in the stricter sense is to attain points
+of view from which the fundamental phenomena and the principles of the
+special sciences can be seen in their relative importance and connection. 
+But philosophy in this stricter sense has always been influenced by
+philosophy in the broader sense.  Greek philosophy came under the influence
+of logic and mathematics, modern philosophy under the influence of natural
+science.  The name of Charles Darwin stands with those of Galileo, Newton,
+and Robert Mayer--names which denote new problems and great alterations in
+our conception of the universe.
+
+First of all we must lay stress on Darwin's own personality.  His deep love
+of truth, his indefatigable inquiry, his wide horizon, and his steady self-
+criticism make him a scientific model, even if his results and theories
+should eventually come to possess mainly an historical interest.  In the
+intellectual domain the primary object is to reach high summits from which
+wide surveys are possible, to reach them toiling honestly upwards by way of
+experience, and then not to turn dizzy when a summit is gained.  Darwinians
+have sometimes turned dizzy, but Darwin never.  He saw from the first the
+great importance of his hypothesis, not only because of its solution of the
+old problem as to the value of the concept of species, not only because of
+the grand picture of natural evolution which it unrolls, but also because
+of the life and inspiration its method would impart to the study of
+comparative anatomy, of instinct and of heredity, and finally because of
+the influence it would exert on the whole conception of existence.  He
+wrote in his note-book in the year 1837:  "My theory would give zest to
+recent and fossil comparative anatomy; it would lead to the study of
+instinct, heredity, and mind-heredity, whole (of) metaphysics."  ("Life and
+Letters of Charles Darwin", Vol. I. page 8.)
+
+We can distinguish four main points in which Darwin's investigations
+possess philosophical importance.
+
+The evolution hypothesis is much older than Darwin; it is, indeed, one of
+the oldest guessings of human thought.  In the eighteenth century it was
+put forward by Diderot and Lamettrie and suggested by Kant (1786).  As we
+shall see later, it was held also by several philosophers in the first half
+of the nineteenth century.  In his preface to "The Origin of Species",
+Darwin mentions the naturalists who were his forerunners.  But he has set
+forth the hypothesis of evolution in so energetic and thorough a manner
+that it perforce attracts the attention of all thoughtful men in a much
+higher degree than it did before the publication of the "Origin".
+
+And further, the importance of his teaching rests on the fact that he, much
+more than his predecessors, even than Lamarck, sought a foundation for his
+hypothesis in definite facts.  Modern science began by demanding--with
+Kepler and Newton--evidence of verae causae; this demand Darwin
+industriously set himself to satisfy--hence the wealth of material which he
+collected by his observations and his experiments.  He not only revived an
+old hypothesis, but he saw the necessity of verifying it by facts.  Whether
+the special cause on which he founded the explanation of the origin of
+species--Natural Selection--is sufficient, is now a subject of discussion. 
+He himself had some doubt in regard to this question, and the criticisms
+which are directed against his hypothesis hit Darwinism rather than Darwin. 
+In his indefatigable search for empirical evidence he is a model even for
+his antagonists:  he has compelled them to approach the problems of life
+along other lines than those which were formerly followed.
+
+Whether the special cause to which Darwin appealed is sufficient or not, at
+least to it is probably due the greater part of the influence which he has
+exerted on the general trend of thought.  "Struggle for existence" and
+"natural selection" are principles which have been applied, more or less,
+in every department of thought.  Recent research, it is true, has
+discovered greater empirical discontinuity--leaps, "mutations"--whereas
+Darwin believed in the importance of small variations slowly accumulated. 
+It has also been shown by the experimental method, which in recent
+biological work has succeeded Darwin's more historical method, that types
+once constituted possess great permanence, the fluctuations being
+restricted within clearly defined boundaries.  The problem has become more
+precise, both as to variation and as to heredity.  The inner conditions of
+life have in both respects shown a greater independence than Darwin had
+supposed in his theory, though he always admitted that the cause of
+variation was to him a great enigma, "a most perplexing problem," and that
+the struggle for life could only occur where variation existed.  But, at
+any rate, it was of the greatest importance that Darwin gave a living
+impression of the struggle for life which is everywhere going on, and to
+which even the highest forms of existence must be amenable.  The
+philosophical importance of these ideas does not stand or fall with the
+answer to the question, whether natural selection is a sufficient
+explanation of the origin of species or not:  it has an independent,
+positive value for everyone who will observe life and reality with an
+unbiassed mind.
+
+In accentuating the struggle for life Darwin stands as a characteristically
+English thinker:  he continues a train of ideas which Hobbes and Malthus
+had already begun.  Moreover in his critical views as to the conception of
+species he had English forerunners; in the middle ages Occam and Duns
+Scotus, in the eighteenth century Berkeley and Hume.  In his moral
+philosophy, as we shall see later, he is an adherent of the school which is
+represented by Hutcheson, Hume and Adam Smith.  Because he is no
+philosopher in the stricter sense of the term, it is of great interest to
+see that his attitude of mind is that of the great thinkers of his nation.
+
+In considering Darwin's influence on philosophy we will begin with an
+examination of the attitude of philosophy to the conception of evolution at
+the time when "The Origin of Species" appeared.  We will then examine the
+effects which the theory of evolution, and especially the idea of the
+struggle for life, has had, and naturally must have, on the discussion of
+philosophical problems.
+
+II.
+
+When "The Origin of Species" appeared fifty years ago Romantic speculation,
+Schelling's and Hegel's philosophy, still reigned on the continent, while
+in England Positivism, the philosophy of Comte and Stuart Mill, represented
+the most important trend of thought.  German speculation had much to say on
+evolution, it even pretended to be a philosophy of evolution.  But then the
+word "evolution" was to be taken in an ideal, not in a real, sense.  To
+speculative thought the forms and types of nature formed a system of ideas,
+within which any form could lead us by continuous transitions to any other.
+It was a classificatory system which was regarded as a divine world of
+thought or images, within which metamorphoses could go on--a condition
+comparable with that in the mind of the poet when one image follows another
+with imperceptible changes.  Goethe's ideas of evolution, as expressed in
+his "Metamorphosen der Pflanzen und der Thiere", belong to this category;
+it is, therefore, incorrect to call him a forerunner of Darwin.  Schelling
+and Hegel held the same idea; Hegel expressly rejected the conception of a
+real evolution in time as coarse and materialistic.  "Nature," he says, "is
+to be considered as a SYSTEM OF STAGES, the one necessarily arising from
+the other, and being the nearest truth of that from which it proceeds; but
+not in such a way that the one is NATURALLY generated by the other; on the
+contrary (their connection lies) in the inner idea which is the ground of
+nature.  The METAMORPHOSIS can be ascribed only to the notion as such,
+because it alone is evolution...It has been a clumsy idea in the older as
+well as in the newer philosophy of nature, to regard the transformation and
+the transition from one natural form and sphere to a higher as an outward
+and actual production."  ("Encyclopaedie der philosophischen
+Wissenschaften" (4th edition), Berlin, 1845, paragraph 249.)
+
+The only one of the philosophers of Romanticism who believed in a real,
+historical evolution, a real production of new species, was Oken. 
+("Lehrbuch der Naturphilosophie", Jena, 1809.)  Danish philosophers, such
+as Treschow (1812) and Sibbern (1846), have also broached the idea of an
+historical evolution of all living beings from the lowest to the highest. 
+Schopenhauer's philosophy has a more realistic character than that of
+Schelling's and Hegel's, his diametrical opposites, though he also belongs
+to the romantic school of thought.  His philosophical and psychological
+views were greatly influenced by French naturalists and philosophers,
+especially by Cabanis and Lamarck.  He praises the "ever memorable
+Lamarck," because he laid so much stress on the "will to live."  But he
+repudiates as a "wonderful error" the idea that the organs of animals
+should have reached their present perfection through a development in time,
+during the course of innumerable generations.  It was, he said, a
+consequence of the low standard of contemporary French philosophy, that
+Lamarck came to the idea of the construction of living beings in time
+through succession!  ("Ueber den Willen in der Natur" (2nd edition),
+Frankfurt a. M., 1854, pages 41-43.)
+
+The positivistic stream of thought was not more in favour of a real
+evolution than was the Romantic school.  Its aim was to adhere to positive
+facts:  it looked with suspicion on far-reaching speculation.  Comte laid
+great stress on the discontinuity found between the different kingdoms of
+nature, as well as within each single kingdom.  As he regarded as
+unscientific every attempt to reduce the number of physical forces, so he
+rejected entirely the hypothesis of Lamarck concerning the evolution of
+species; the idea of species would in his eyes absolutely lose its
+importance if a transition from species to species under the influence of
+conditions of life were admitted.  His disciples (Littre, Robin) continued
+to direct against Darwin the polemics which their master had employed
+against Lamarck.  Stuart Mill, who, in the theory of knowledge, represented
+the empirical or positivistic movement in philosophy--like his English
+forerunners from Locke to Hume--founded his theory of knowledge and morals
+on the experience of the single individual.  He sympathised with the theory
+of the original likeness of all individuals and derived their differences,
+on which he practically and theoretically laid much stress, from the
+influence both of experience and education, and, generally, of physical and
+social causes.  He admitted an individual evolution, and, in the human
+species, an evolution based on social progress; but no physiological
+evolution of species.  He was afraid that the hypothesis of heredity would
+carry us back to the old theory of "innate" ideas.
+
+Darwin was more empirical than Comte and Mill; experience disclosed to him
+a deeper continuity than they could find; closer than before the nature and
+fate of the single individual were shown to be interwoven in the great web
+binding the life of the species with nature as a whole.  And the continuity
+which so many idealistic philosophers could find only in the world of
+thought, he showed to be present in the world of reality.
+
+III.
+
+Darwin's energetic renewal of the old idea of evolution had its chief
+importance in strengthening the conviction of this real continuity in the
+world, of continuity in the series of form and events.  It was a great
+support for all those who were prepared to base their conception of life on
+scientific grounds.  Together with the recently discovered law of the
+conservation of energy, it helped to produce the great realistic movement
+which characterises the last third of the nineteenth century.  After the
+decline of the Romantic movement people wished to have firmer ground under
+their feet and reality now asserted itself in a more emphatic manner than
+in the period of Romanticism.  It was easy for Hegel to proclaim that "the
+real" was "the rational," and that "the rational" was "the real":  reality
+itself existed for him only in the interpretation of ideal reason, and if
+there was anything which could not be merged in the higher unity of
+thought, then it was only an example of the "impotence of nature to hold to
+the idea."  But now concepts are to be founded on nature and not on any
+system of categories too confidently deduced a priori.  The new devotion to
+nature had its recompense in itself, because the new points of view made us
+see that nature could indeed "hold to ideas," though perhaps not to those
+which we had cogitated beforehand.
+
+A most important question for philosophers to answer was whether the new
+views were compatible with an idealistic conception of life and existence.
+Some proclaimed that we have now no need of any philosophy beyond the
+principles of the conservation of matter and energy and the principle of
+natural evolution:  existence should and could be definitely and completely
+explained by the laws of material nature.  But abler thinkers saw that the
+thing was not so simple.  They were prepared to give the new views their
+just place and to examine what alterations the old views must undergo in
+order to be brought into harmony with the new data.
+
+The realistic character of Darwin's theory was shown not only in the idea
+of natural continuity, but also, and not least, in the idea of the cause
+whereby organic life advances step by step.  This idea--the idea of the
+struggle for life--implied that nothing could persist, if it had no power
+to maintain itself under the given conditions.  Inner value alone does not
+decide.  Idealism was here put to its hardest trial.  In continuous
+evolution it could perhaps still find an analogy to the inner evolution of
+ideas in the mind; but in the demand for power in order to struggle with
+outward conditions Realism seemed to announce itself in its most brutal
+form.  Every form of Idealism had to ask itself seriously how it was going
+to "struggle for life" with this new Realism.
+
+We will now give a short account of the position which leading thinkers in
+different countries have taken up in regard to this question.
+
+I.  Herbert Spencer was the philosopher whose mind was best prepared by his
+own previous thinking to admit the theory of Darwin to a place in his
+conception of the world.  His criticism of the arguments which had been put
+forward against the hypothesis of Lamarck, showed that Spencer, as a young
+man, was an adherent to the evolution idea.  In his "Social Statics" (1850)
+he applied this idea to human life and moral civilisation.  In 1852 he
+wrote an essay on "The Development Hypothesis", in which he definitely
+stated his belief that the differentiation of species, like the
+differentiation within a single organism, was the result of development. 
+In the first edition of his "Psychology" (1855) he took a step which put
+him in opposition to the older English school (from Locke to Mill):  he
+acknowledged "innate ideas" so far as to admit the tendency of acquired
+habits to be inherited in the course of generations, so that the nature and
+functions of the individual are only to be understood through its
+connection with the life of the species.  In 1857, in his essay on
+"Progress", he propounded the law of differentiation as a general law of
+evolution, verified by examples from all regions of experience, the
+evolution of species being only one of these examples.  On the effect which
+the appearance of "The Origin of Species" had on his mind he writes in his
+"Autobiography":  "Up to that time...I held that the sole cause of organic
+evolution is the inheritance of functionally-produced modifications.  The
+"Origin of Species" made it clear to me that I was wrong, and that the
+larger part of the facts cannot be due to any such cause...To have the
+theory of organic evolution justified was of course to get further support
+for that theory of evolution at large with which...all my conceptions were
+bound up."  (Spencer, "Autobiography", Vol. II. page 50, London, 1904.) 
+Instead of the metaphorical expression "natural selection," Spencer
+introduced the term "survival of the fittest," which found favour with
+Darwin as well as with Wallace.
+
+In working out his ideas of evolution, Spencer found that differentiation
+was not the only form of evolution.  In its simplest form evolution is
+mainly a concentration, previously scattered elements being integrated and
+losing independent movement.  Differentiation is only forthcoming when
+minor wholes arise within a greater whole.  And the highest form of
+evolution is reached when there is a harmony between concentration and
+differentiation, a harmony which Spencer calls equilibration and which he
+defines as a moving equilibrium.  At the same time this definition enables
+him to illustrate the expression "survival of the fittest."  "Every living
+organism exhibits such a moving equilibrium--a balanced set of functions
+constituting its life; and the overthrow of this balanced set of functions
+or moving equilibrium is what we call death.  Some individuals in a species
+are so constituted that their moving equilibria are less easily overthrown
+than those of other individuals; and these are the fittest which survive,
+or, in Mr Darwin's language, they are the select which nature preserves." 
+(Ibid. page 100.)  Not only in the domain of organic life, but in all
+domains, the summit of evolution is, according to Spencer, characterised by
+such a harmony--by a moving equilibrium.
+
+Spencer's analysis of the concept of evolution, based on a great variety of
+examples, has made this concept clearer and more definite than before.  It
+contains the three elements; integration, differentiation and
+equilibration.  It is true that a concept which is to be valid for all
+domains of experience must have an abstract character, and between the
+several domains there is, strictly speaking, only a relation of analogy. 
+So there is only analogy between psychical and physical evolution.  But
+this is no serious objection, because general concepts do not express more
+than analogies between the phenomena which they represent.  Spencer takes
+his leading terms from the material world in defining evolution (in the
+simplest form) as integration of matter and dissipation of movement; but as
+he--not always quite consistently (Cf. my letter to him, 1876, now printed
+in Duncan's "Life and Letters of Herbert Spencer", page 178, London,
+1908.)--assumed a correspondence of mind and matter, he could very well
+give these terms an indirect importance for psychical evolution.  Spencer
+has always, in my opinion with full right, repudiated the ascription of
+materialism.  He is no more a materialist than Spinoza.  In his "Principles
+of Psychology" (paragraph 63) he expressed himself very clearly:  "Though
+it seems easier to translate so-called matter into so-called spirit, than
+to translate so-called spirit into so-called matter--which latter is indeed
+wholly impossible--yet no translation can carry us beyond our symbols." 
+These words lead us naturally to a group of thinkers whose starting-point
+was psychical evolution.  But we have still one aspect of Spencer's
+philosophy to mention.
+
+Spencer founded his "laws of evolution" on an inductive basis, but he was
+convinced that they could be deduced from the law of the conservation of
+energy.  Such a deduction is, perhaps, possible for the more elementary
+forms of evolution, integration and differentiation; but it is not possible
+for the highest form, the equilibration, which is a harmony of integration
+and differentiation.  Spencer can no more deduce the necessity for the
+eventual appearance of "moving equilibria" of harmonious totalities than
+Hegel could guarantee the "higher unities" in which all contradictions
+should be reconciled.  In Spencer's hands the theory of evolution acquired
+a more decidedly optimistic character than in Darwin's; but I shall deal
+later with the relation of Darwin's hypothesis to the opposition of
+optimism and pessimism.
+
+II.  While the starting-point of Spencer was biological or cosmological,
+psychical evolution being conceived as in analogy with physical, a group of
+eminent thinkers--in Germany Wundt, in France Fouillee, in Italy Ardigo--
+took, each in his own manner, their starting-point in psychical evolution
+as an original fact and as a type of all evolution, the hypothesis of
+Darwin coming in as a corroboration and as a special example.  They
+maintain the continuity of evolution; they find this character most
+prominent in psychical evolution, and this is for them a motive to demand a
+corresponding continuity in the material, especially in the organic domain.
+
+To Wundt and Fouillee the concept of will is prominent.  They see the type
+of all evolution in the transformation of the life of will from blind
+impulse to conscious choice; the theories of Lamarck and Darwin are used to
+support the view that there is in nature a tendency to evolution in steady
+reciprocity with external conditions.  The struggle for life is here only a
+secondary fact.  Its apparent prominence is explained by the circumstance
+that the influence of external conditions is easily made out, while inner
+conditions can be verified only through their effects.  For Ardigo the
+evolution of thought was the starting-point and the type:  in the evolution
+of a scientific hypothesis we see a progress from the indefinite
+(indistinto) to the definite (distinto), and this is a characteristic of
+all evolution, as Ardigo has pointed out in a series of works.  The
+opposition between indistinto and distinto corresponds to Spencer's
+opposition between homogeneity and heterogeneity.  The hypothesis of the
+origin of differences of species from more simple forms is a special
+example of the general law of evolution.
+
+In the views of Wundt and Fouillee we find the fundamental idea of
+idealism:  psychical phenomena as expressions of the innermost nature of
+existence.  They differ from the older Idealism in the great stress which
+they lay on evolution as a real, historical process which is going on
+through steady conflict with external conditions.  The Romantic dread of
+reality is broken.  It is beyond doubt that Darwin's emphasis on the
+struggle for life as a necessary condition of evolution has been a very
+important factor in carrying philosophy back to reality from the heaven of
+pure ideas.  The philosophy of Ardigo, on the other side, appears more as a
+continuation and deepening of positivism, though the Italian thinker
+arrived at his point of view independently of French-English positivism. 
+The idea of continuous evolution is here maintained in opposition to
+Comte's and Mill's philosophy of discontinuity.  From Wundt and Fouillee
+Ardigo differs in conceiving psychical evolution not as an immediate
+revelation of the innermost nature of existence, but only as a single,
+though the most accessible example, of evolution.
+
+III.  To the French philosophers Boutroux and Bergson, evolution proper is
+continuous and qualitative, while outer experience and physical science
+give us fragments only, sporadic processes and mechanical combinations.  To
+Bergson, in his recent work "L'Evolution Creatrice", evolution consists in
+an elan de vie which to our fragmentary observation and analytic reflexion
+appears as broken into a manifold of elements and processes.  The concept
+of matter in its scientific form is the result of this breaking asunder,
+essential for all scientific reflexion.  In these conceptions the strongest
+opposition between inner and outer conditions of evolution is expressed: 
+in the domain of internal conditions spontaneous development of qualitative
+forms--in the domain of external conditions discontinuity and mechanical
+combination.
+
+We see, then, that the theory of evolution has influenced philosophy in a
+variety of forms.  It has made idealistic thinkers revise their relation to
+the real world; it has led positivistic thinkers to find a closer
+connection between the facts on which they based their views; it has made
+us all open our eyes for new possibilities to arise through the prima facie
+inexplicable "spontaneous" variations which are the condition of all
+evolution.  This last point is one of peculiar interest.  Deeper than
+speculative philosophy and mechanical science saw in the days of their
+triumph, we catch sight of new streams, whose sources and laws we have
+still to discover.  Most sharply does this appear in the theory of
+mutation, which is only a stronger accentuation of a main point in
+Darwinism.  It is interesting to see that an analogous problem comes into
+the foreground in physics through the discovery of radioactive phenomena,
+and in psychology through the assumption of psychical new formations (as
+held by Boutroux, William James and Bergson).  From this side, Darwin's
+ideas, as well as the analogous ideas in other domains, incite us to
+renewed examination of our first principles, their rationality and their
+value.  On the other hand, his theory of the struggle for existence
+challenges us to examine the conditions and discuss the outlook as to the
+persistence of human life and society and of the values that belong to
+them.  It is not enough to hope (or fear?) the rising of new forms; we have
+also to investigate the possibility of upholding the forms and ideals which
+have hitherto been the bases of human life.  Darwin has here given his age
+the most earnest and most impressive lesson.  This side of Darwin's theory
+is of peculiar interest to some special philosophical problems to which I
+now pass.
+
+IV.
+
+Among philosophical problems the problem of knowledge has in the last
+century occupied a foremost place.  It is natural, then, to ask how Darwin
+and the hypothesis whose most eminent representative he is, stand to this
+problem.
+
+Darwin started an hypothesis.  But every hypothesis is won by inference
+from certain presuppositions, and every inference is based on the general
+principles of human thought.  The evolution hypothesis presupposes, then,
+human thought and its principles.  And not only the abstract logical
+principles are thus presupposed.  The evolution hypothesis purports to be
+not only a formal arrangement of phenomena, but to express also the law of
+a real process.  It supposes, then, that the real data--all that in our
+knowledge which we do not produce ourselves, but which we in the main
+simply receive--are subjected to laws which are at least analogous to the
+logical relations of our thoughts; in other words, it assumes the validity
+of the principle of causality.  If organic species could arise without
+cause there would be no use in framing hypotheses.  Only if we assume the
+principle of causality, is there a problem to solve.
+
+Though Darwinism has had a great influence on philosophy considered as a
+striving after a scientific view of the world, yet here is a point of view
+--the epistemological--where philosophy is not only independent but reaches
+beyond any result of natural science.  Perhaps it will be said:  the powers
+and functions of organic beings only persist (perhaps also only arise) when
+they correspond sufficiently to the conditions under which the struggle of
+life is to go on.  Human thought itself is, then, a variation (or a
+mutation) which has been able to persist and to survive.  Is not, then, the
+problem of knowledge solved by the evolution hypothesis?  Spencer had given
+an affirmative answer to this question before the appearance of "The Origin
+of Species".  For the individual, he said, there is an a priori, original,
+basis (or Anlage) for all mental life; but in the species all powers have
+developed in reciprocity with external conditions.  Knowledge is here
+considered from the practical point of view, as a weapon in the struggle
+for life, as an "organon" which has been continuously in use for
+generations.  In recent years the economic or pragmatic epistemology, as
+developed by Avenarius and Mach in Germany, and by James in America, points
+in the same direction.  Science, it is said, only maintains those
+principles and presuppositions which are necessary to the simplest and
+clearest orientation in the world of experience.  All assumptions which
+cannot be applied to experience and to practical work, will successively be
+eliminated.
+
+In these views a striking and important application is made of the idea of
+struggle for life to the development of human thought.  Thought must, as
+all other things in the world, struggle for life.  But this whole
+consideration belongs to psychology, not to the theory of knowledge
+(epistemology), which is concerned only with the validity of knowledge, not
+with its historical origin.  Every hypothesis to explain the origin of
+knowledge must submit to cross-examination by the theory of knowledge,
+because it works with the fundamental forms and principles of human
+thought.  We cannot go further back than these forms and principles, which
+it is the aim of epistemology to ascertain and for which no further reason
+can be given.  (The present writer, many years ago, in his "Psychology"
+(Copenhagen, 1882; English translation London, 1891), criticised the
+evolutionistic treatment of the problem of knowledge from the Kantian point
+of view.)
+
+But there is another side of the problem which is, perhaps, of more
+importance and which epistemology generally overlooks.  If new variations
+can arise, not only in organic but perhaps also in inorganic nature, new
+tasks are placed before the human mind.  The question is, then, if it has
+forms in which there is room for the new matter?  We are here touching a
+possibility which the great master of epistemology did not bring to light.
+Kant supposed confidently that no other matter of knowledge could stream
+forth from the dark source which he called "the thing-in-itself," than such
+as could be synthesised in our existing forms of knowledge.  He mentions
+the possibility of other forms than the human, and warns us against the
+dogmatic assumption that the human conception of existence should be
+absolutely adequate.  But he seems to be quite sure that the thing-in-
+itself works constantly, and consequently always gives us only what our
+powers can master.  This assumption was a consequence of Kant's
+rationalistic tendency, but one for which no warrant can be given. 
+Evolutionism and systematism are opposing tendencies which can never be
+absolutely harmonised one with the other.  Evolution may at any time break
+some form which the system-monger regards as finally established.  Darwin
+himself felt a great difference in looking at variation as an evolutionist
+and as a systematist.  When he was working at his evolution theory, he was
+very glad to find variations; but they were a hindrance to him when he
+worked as a systematist, in preparing his work on Cirripedia.  He says in a
+letter:  "I had thought the same parts of the same species more resemble
+(than they do anyhow in Cirripedia) objects cast in the same mould. 
+Systematic work would be easy were it not for this confounded variation,
+which, however, is pleasant to me as a speculatist, though odious to me as
+a systematist."  ("Life and Letters", Vol. II. page 37.)  He could indeed
+be angry with variations even as an evolutionist; but then only because he
+could not explain them, not because he could not classify them.  "If, as I
+must think, external conditions produce little DIRECT effect, what the
+devil determines each particular variation?"  (Ibid. page 232.)  What
+Darwin experienced in his particular domain holds good of all knowledge. 
+All knowledge is systematic, in so far as it strives to put phenomena in
+quite definite relations, one to another.  But the systematisation can
+never be complete.  And here Darwin has contributed much to widen the world
+for us.  He has shown us forces and tendencies in nature which make
+absolute systems impossible, at the same time that they give us new objects
+and problems.  There is still a place for what Lessing called "the
+unceasing striving after truth," while "absolute truth" (in the sense of a
+closed system) is unattainable so long as life and experience are going on.
+
+There is here a special remark to be made.  As we have seen above, recent
+research has shown that natural selection or struggle for life is no
+explanation of variations.  Hugo de Vries distinguishes between partial and
+embryonal variations, or between variations and mutations, only the last-
+named being heritable, and therefore of importance for the origin of new
+species.  But the existence of variations is not only of interest for the
+problem of the origin of species; it has also a more general interest.  An
+individual does not lose its importance for knowledge, because its
+qualities are not heritable.  On the contrary, in higher beings at least,
+individual peculiarities will become more and more independent objects of
+interest.  Knowledge takes account of the biographies not only of species,
+but also of individuals:  it seeks to find the law of development of the
+single individual.  (The new science of Ecology occupies an intermediate
+position between the biography of species and the biography of individuals.
+Compare "Congress of Arts and Science", St Louis, Vol. V. 1906 (the Reports
+of Drude and Robinson) and the work of my colleague E. Warming.)  As
+Leibniz said long ago, individuality consists in the law of the changes of
+a being.  "La loi du changement fait l'individualite de chaque substance." 
+Here is a world which is almost new for science, which till now has mainly
+occupied itself with general laws and forms.  But these are ultimately only
+means to understand the individual phenomena, in whose nature and history a
+manifold of laws and forms always cooperate.  The importance of this remark
+will appear in the sequel.
+
+V.
+
+To many people the Darwinian theory of natural selection or struggle for
+existence seemed to change the whole conception of life, and particularly
+all the conditions on which the validity of ethical ideas depends.  If only
+that has persistence which can be adapted to a given condition, what will
+then be the fate of our ideals, of our standards of good and evil?  Blind
+force seems to reign, and the only thing that counts seems to be the most
+heedless use of power.  Darwinism, it was said, has proclaimed brutality. 
+No other difference seems permanent save that between the sound, powerful
+and happy on the one side, the sick, feeble and unhappy on the other; and
+every attempt to alleviate this difference seems to lead to general
+enervation.  Some of those who interpreted Darwinism in this manner felt an
+aesthetic delight in contemplating the heedlessness and energy of the great
+struggle for existence and anticipated the realisation of a higher human
+type as the outcome of it:  so Nietzsche and his followers.  Others
+recognising the same consequences in Darwinism regarded these as one of the
+strongest objections against it; so Duhring and Kropotkin (in his earlier
+works).
+
+This interpretation of Darwinism was frequent in the interval between the
+two main works of Darwin--"The Origin of Species" and "The Descent of Man". 
+But even during this interval it was evident to an attentive reader that
+Darwin himself did not found his standard of good and evil on the features
+of the life of nature he had emphasised so strongly.  He did not justify
+the ways along which nature reached its ends; he only pointed them out. 
+The "real" was not to him, as to Hegel, one with the "rational."  Darwin
+has, indeed, by his whole conception of nature, rendered a great service to
+ethics in making the difference between the life of nature and the ethical
+life appear in so strong a light.  The ethical problem could now be stated
+in a sharper form than before.  But this was not the first time that the
+idea of the struggle for life was put in relation to the ethical problem. 
+In the seventeenth century Thomas Hobbes gave the first impulse to the
+whole modern discussion of ethical principles in his theory of bellum
+omnium contra omnes.  Men, he taught, are in the state of nature enemies
+one of another, and they live either in fright or in the glory of power. 
+But it was not the opinion of Hobbes that this made ethics impossible.  On
+the contrary, he found a standard for virtue and vice in the fact that some
+qualities and actions have a tendency to bring us out of the state of war
+and to secure peace, while other qualities have a contrary tendency.  In
+the eighteenth century even Immanuel Kant's ideal ethics had--so far as can
+be seen--a similar origin.  Shortly before the foundation of his definitive
+ethics, Kant wrote his "Idee zu einer allgemeinen Weltgeschichte" (1784),
+where--in a way which reminds us of Hobbes, and is prophetic of Darwin--he
+describes the forward-driving power of struggle in the human world.  It is
+here as with the struggle of the trees for light and air, through which
+they compete with one another in height.  Anxiety about war can only be
+allayed by an ordinance which gives everyone his full liberty under
+acknowledgment of the equal liberty of others.  And such ordinance and
+acknowledgment are also attributes of the content of the moral law, as Kant
+proclaimed it in the year after the publication of his essay (1785)  (Cf.
+my "History of Modern Philosophy" (English translation London, 1900), I.
+pages 76-79.)  Kant really came to his ethics by the way of evolution,
+though he afterwards disavowed it.  Similarly the same line of thought may
+be traced in Hegel though it has been disguised in the form of speculative
+dialectics.  ("Herrschaft und Knechtschaft", "Phanomenologie des Geistes",
+IV. A., Leiden, 1907.)  And in Schopenhauer's theory of the blind will to
+live and its abrogation by the ethical feeling, which is founded on
+universal sympathy, we have a more individualistic form of the same idea.
+
+It was, then, not entirely a foreign point of view which Darwin introduced
+into ethical thought, even if we take no account of the poetical character
+of the word "struggle" and of the more direct adaptation, through the use
+and non-use of power, which Darwin also emphasised.  In "The Descent of
+Man" he has devoted a special chapter ("The Descent of Man", Vol. I. Ch.
+iii.) to a discussion of the origin of the ethical consciousness.  The
+characteristic expression of this consciousness he found, just as Kant did,
+in the idea of "ought"; it was the origin of this new idea which should be
+explained.  His hypothesis was that the ethical "ought" has its origin in
+the social and parental instincts, which, as well as other instincts (e.g.
+the instinct of self-preservation), lie deeper than pleasure and pain.  In
+many species, not least in the human species, these instincts are fostered
+by natural selection; and when the powers of memory and comparison are
+developed, so that single acts can be valued according to the claims of the
+deep social instinct, then consciousness of duty and remorse are possible. 
+Blind instinct has developed to conscious ethical will.
+
+As already stated, Darwin, as a moral philosopher belongs to the school
+that was founded by Shaftesbury, and was afterwards represented by
+Hutcheson, Hume, Adam Smith, Comte and Spencer.  His merit is, first, that
+he has given this tendency of thought a biological foundation, and that he
+has stamped on it a doughty character in showing that ethical ideas and
+sentiments, rightly conceived, are forces which are at work in the struggle
+for life.
+
+There are still many questions to solve.  Not only does the ethical
+development within the human species contain features still unexplained
+(The works of Westermarck and Hobhouse throw new light on many of these
+features.); but we are confronted by the great problem whether after all a
+genetic historical theory can be of decisive importance here.  To every
+consequent ethical consciousness there is a standard of value, a primordial
+value which determines the single ethical judgments as their last
+presupposition, and the "rightness" of this basis, the "value" of this
+value can as little be discussed as the "rationality" of our logical
+principles.  There is here revealed a possibility of ethical scepticism
+which evolutionistic ethics (as well as intuitive or rationalistic ethics)
+has overlooked.  No demonstration can show that the results of the ethical
+development are definitive and universal.  We meet here again with the
+important opposition of systematisation and evolution.  There will, I
+think, always be an open question here, though comparative ethics, of which
+we have so far only the first attempts, can do much to throw light on it.
+
+It would carry us too far to discuss all the philosophical works on ethics,
+which have been influenced directly or indirectly by evolutionism.  I may,
+however, here refer to the book of C.M. Williams, "A Review of the Systems
+of Ethics founded on the Theory of Evolution" (New York and London, 1893.),
+in which, besides Darwin, the following authors are reviewed:  Wallace,
+Haeckel, Spencer, Fiske, Rolph, Barratt, Stephen, Carneri, Hoffding,
+Gizycki, Alexander, Ree.  As works which criticise evolutionistic ethics
+from an intuitive point of view and in an instructive way, may be cited: 
+Guyau "La morale anglaise contemporaine" (Paris, 1879.), and Sorley,
+"Ethics of Naturalism".  I will only mention some interesting contributions
+to ethical discussion which can be found in Darwinism besides the idea of
+struggle for life.
+
+The attention which Darwin has directed to variations has opened our eyes
+to the differences in human nature as well as in nature generally.  There
+is here a fact of great importance for ethical thought, no matter from what
+ultimate premiss it starts.  Only from a very abstract point of view can
+different individuals be treated in the same manner.  The most eminent
+ethical thinkers, men such as Jeremy Bentham and Immanuel Kant, who
+discussed ethical questions from very opposite standpoints, agreed in
+regarding all men as equal in respect of ethical endowment.  In regard to
+Bentham, Leslie Stephen remarks:  "He is determined to be thoroughly
+empirical, to take men as he found them.  But his utilitarianism supposed
+that men's views of happiness and utility were uniform and clear, and that
+all that was wanted was to show them the means by which their ends could be
+reached."  ("English literature and society in the eighteenth century",
+London, 1904, page 187.)  And Kant supposed that every man would find the
+"categorical imperative" in his consciousness, when he came to sober
+reflexion, and that all would have the same qualifications to follow it. 
+But if continual variations, great or small, are going on in human nature,
+it is the duty of ethics to make allowance for them, both in making claims,
+and in valuing what is done.  A new set of ethical problems have their
+origin here.  (Cf. my paper, "The law of relativity in Ethics,"
+"International Journal of Ethics", Vol. I. 1891, pages 37-62.)  It is an
+interesting fact that Stuart Mill's book "On Liberty" appeared in the same
+year as "The Origin of Species".  Though Mill agreed with Bentham about the
+original equality of all men's endowments, he regarded individual
+differences as a necessary result of physical and social influences, and he
+claimed that free play shall be allowed to differences of character so far
+as is possible without injury to other men.  It is a condition of
+individual and social progress that a man's mode of action should be
+determined by his own character and not by tradition and custom, nor by
+abstract rules.  This view was to be corroborated by the theory of Darwin.
+
+But here we have reached a point of view from which the criticism, which in
+recent years has often been directed against Darwin--that small variations
+are of no importance in the struggle for life--is of no weight.  From an
+ethical standpoint, and particularly from the ethical standpoint of Darwin
+himself, it is a duty to foster individual differences that can be
+valuable, even though they can neither be of service for physical
+preservation nor be physically inherited.  The distinction between
+variation and mutation is here without importance.  It is quite natural
+that biologists should be particularly interested in such variations as can
+be inherited and produce new species.  But in the human world there is not
+only a physical, but also a mental and social heredity.  When an ideal
+human character has taken form, then there is shaped a type, which through
+imitation and influence can become an important factor in subsequent
+development, even if it cannot form a species in the biological sense of
+the word.  Spiritually strong men often succumb in the physical struggle
+for life; but they can nevertheless be victorious through the typical
+influence they exert, perhaps on very distant generations, if the
+remembrance of them is kept alive, be it in legendary or in historical
+form.  Their very failure can show that a type has taken form which is
+maintained at all risks, a standard of life which is adhered to in spite of
+the strongest opposition.  The question "to be or not to be" can be put
+from very different levels of being:  it has too often been considered a
+consequence of Darwinism that this question is only to be put from the
+lowest level.  When a stage is reached, where ideal (ethical, intellectual,
+aesthetic) interests are concerned, the struggle for life is a struggle for
+the preservation of this stage.  The giving up of a higher standard of life
+is a sort of death; for there is not only a physical, there is also a
+spiritual, death.
+
+VI.
+
+The Socratic character of Darwin's mind appears in his wariness in drawing
+the last consequences of his doctrine, in contrast both with the audacious
+theories of so many of his followers and with the consequences which his
+antagonists were busy in drawing.  Though he, as we have seen, saw from the
+beginning that his hypothesis would occasion "a whole of metaphysics," he
+was himself very reserved as to the ultimate questions, and his answers to
+such questions were extorted from him.
+
+As to the question of optimism and pessimism, Darwin held that though pain
+and suffering were very often the ways by which animals were led to pursue
+that course of action which is most beneficial to the species, yet
+pleasurable feelings were the most habitual guides.  "We see this in the
+pleasure from exertion, even occasionally from great exertion of the body
+or mind, in the pleasure of our daily meals, and especially in the pleasure
+derived from sociability, and from loving our families."  But there was to
+him so much suffering in the world that it was a strong argument against
+the existence of an intelligent First Cause.  ("Life and Letters" Vol. I.
+page 310.)
+
+It seems to me that Darwin was not so clear on another question, that of
+the relation between improvement and adaptation.  He wrote to Lyell:  "When
+you contrast natural selection and 'improvement,' you seem always to
+overlook...that every step in the natural selection of each species implies
+improvement in that species IN RELATION TO ITS CONDITION OF
+LIFE...Improvement implies, I suppose, EACH FORM OBTAINING MANY PARTS OR
+ORGANS, all excellently adapted for their functions."  "All this," he adds,
+"seems to me quite compatible with certain forms fitted for simple
+conditions, remaining unaltered, or being degraded."  (Ibid. Vol. II. page
+177.)  But the great question is, if the conditions of life will in the
+long run favour "improvement" in the sense of differentiation (or harmony
+of differentiation and integration).  Many beings are best adapted to their
+conditions of life if they have few organs and few necessities.  Pessimism
+would not only be the consequence, if suffering outweighed happiness, but
+also if the most elementary forms of happiness were predominant, or if
+there were a tendency to reduce the standard of life to the simplest
+possible, the contentment of inertia or stable equilibrium.  There are
+animals which are very highly differentiated and active in their young
+state, but later lose their complex organisation and concentrate themselves
+on the one function of nutrition.  In the human world analogies to this
+sort of adaptation are not wanting.  Young "idealists" very often end as
+old "Philistines."  Adaptation and progress are not the same.
+
+Another question of great importance in respect to human evolution is,
+whether there will be always a possibility for the existence of an impulse
+to progress, an impulse to make great claims on life, to be active and to
+alter the conditions of life instead of adapting to them in a passive
+manner.  Many people do not develop because they have too few necessities,
+and because they have no power to imagine other conditions of life than
+those under which they live.  In his remarks on "the pleasure from
+exertion" Darwin has a point of contact with the practical idealism of
+former times--with the ideas of Lessing and Goethe, of Condorcet and
+Fichte.  The continual striving which was the condition of salvation to
+Faust's soul, is also the condition of salvation to mankind.  There is a
+holy fire which we ought to keep burning, if adaptation is really to be
+improvement.  If, as I have tried to show in my "Philosophy of Religion",
+the innermost core of all religion is faith in the persistence of value in
+the world, and if the highest values express themselves in the cry
+"Excelsior!" then the capital point is, that this cry should always be
+heard and followed.  We have here a corollary of the theory of evolution in
+its application to human life.
+
+Darwin declared himself an agnostic, not only because he could not
+harmonise the large amount of suffering in the world with the idea of a God
+as its first cause, but also because he "was aware that if we admit a first
+cause, the mind still craves to know whence it came and how it arose." 
+("Life and Letters", Vol. I. page 306.)  He saw, as Kant had seen before
+him and expressed in his "Kritik der Urtheilskraft", that we cannot accept
+either of the only two possibilities which we are able to conceive:  chance
+(or brute force) and design.  Neither mechanism nor teleology can give an
+absolute answer to ultimate questions.  The universe, and especially the
+organic life in it, can neither be explained as a mere combination of
+absolute elements nor as the effect of a constructing thought.  Darwin
+concluded, as Kant, and before him Spinoza, that the oppositions and
+distinctions which our experience presents, cannot safely be regarded as
+valid for existence in itself.  And, with Kant and Fichte, he found his
+stronghold in the conviction that man has something to do, even if he
+cannot solve all enigmas.  "The safest conclusion seems to me that the
+whole subject is beyond the scope of man's intellect; but man can do his
+duty."  (Ibid. page 307.)
+
+Is this the last word of human thought?  Does not the possibility, that man
+can do his duty, suppose that the conditions of life allow of continuous
+ethical striving, so that there is a certain harmony between cosmic order
+and human ideals?  Darwin himself has shown how the consciousness of duty
+can arise as a natural result of evolution.  Moreover there are lines of
+evolution which have their end in ethical idealism, in a kingdom of values,
+which must struggle for life as all things in the world must do, but a
+kingdom which has its firm foundation in reality.
+
+
+XXIII.  DARWINISM AND SOCIOLOGY.
+
+By C. BOUGLE.
+Professor of Social Philosophy in the University of Toulouse and Deputy-
+Professor at the Sorbonne, Paris.
+
+How has our conception of social phenomena, and of their history, been
+affected by Darwin's conception of Nature and the laws of its
+transformations?  To what extent and in what particular respects have the
+discoveries and hypotheses of the author of "The Origin of Species" aided
+the efforts of those who have sought to construct a science of society?
+
+To such a question it is certainly not easy to give any brief or precise
+answer.  We find traces of Darwinism almost everywhere.  Sociological
+systems differing widely from each other have laid claim to its authority;
+while, on the other hand, its influence has often made itself felt only in
+combination with other influences.  The Darwinian thread is worked into a
+hundred patterns along with other threads.
+
+To deal with the problem, we must, it seems, first of all distinguish the
+more general conclusions in regard to the evolution of living beings, which
+are the outcome of Darwinism, from the particular explanations it offers of
+the ways and means by which that evolution is effected.  That is to say, we
+must, as far as possible, estimate separately the influence of Darwin as an
+evolutionist and Darwin as a selectionist.
+
+The nineteenth century, said Cournot, has witnessed a mighty effort to
+"reintegrer l'homme dans la nature."  From divers quarters there has been a
+methodical reaction against the persistent dualism of the Cartesian
+tradition, which was itself the unconscious heir of the Christian
+tradition.  Even the philosophy of the eighteenth century, materialistic as
+were for the most part the tendencies of its leaders, seemed to revere man
+as a being apart, concerning whom laws might be formulated a priori.  To
+bring him down from his pedestal there was needed the marked predominance
+of positive researches wherein no account was taken of the "pride of man." 
+There can be no doubt that Darwin has done much to familiarise us with this
+attitude.  Take for instance the first part of "The Descent of Man":  it is
+an accumulation of typical facts, all tending to diminish the distance
+between us and our brothers, the lower animals.  One might say that the
+naturalist had here taken as his motto, "Whosoever shall exalt himself
+shall be abased; and he that shall humble himself shall be exalted." 
+Homologous structures, the survival in man of certain organs of animals,
+the rudiments in the animal of certain human faculties, a multitude of
+facts of this sort, led Darwin to the conclusion that there is no ground
+for supposing that the "king of the universe" is exempt from universal
+laws.  Thus belief in the imperium in imperio has been, as it were,
+whittled away by the progress of the naturalistic spirit, itself
+continually strengthened by the conquests of the natural sciences.  The
+tendency may, indeed, drag the social sciences into overstrained analogies,
+such, for instance, as the assimilation of societies to organisms.  But it
+will, at least, have had the merit of helping sociology to shake off the
+pre-conception that the groups formed by men are artificial, and that
+history is completely at the mercy of chance.  Some years before the
+appearance of "The Origin of Species", Auguste Comte had pointed out the
+importance, as regards the unification of positive knowledge, of the
+conviction that the social world, the last refuge of spiritualism, is
+itself subject to determininism.  It cannot be doubted that the movement of
+thought which Darwin's discoveries promoted contributed to the spread of
+this conviction, by breaking down the traditional barrier which cut man off
+from Nature.
+
+But Nature, according to modern naturalists, is no immutable thing:  it is
+rather perpetual movement, continual progression.  Their discoveries batter
+a breach directly into the Aristotelian notion of species; they refuse to
+see in the animal world a collection of immutable types, distinct from all
+eternity, and corresponding, as Cuvier said, to so many particular thoughts
+of the Creator.  Darwin especially congratulated himself upon having been
+able to deal this doctrine the coup de grace:  immutability is, he says,
+his chief enemy; and he is concerned to show--therein following up Lyell's
+work--that everything in the organic world, as in the inorganic, is
+explained by insensible but incessant transformations.  "Nature makes no
+leaps"--"Nature knows no gaps":  these two dicta form, as it were, the two
+landmarks between which Darwin's idea of transformation is worked out. 
+That is to say, the development of Darwinism is calculated to further the
+application of the philosophy of Becoming to the study of human
+institutions.
+
+The progress of the natural sciences thus brings unexpected reinforcements
+to the revolution which the progress of historical discipline had begun. 
+The first attempt to constitute an actual science of social phenomena--
+that, namely, of the economists--had resulted in laws which were called
+natural, and which were believed to be eternal and universal, valid for all
+times and all places.  But this perpetuality, brother, as Knies said, of
+the immutability of the old zoology, did not long hold out against the ever
+swelling tide of the historical movement.  Knowledge of the transformations
+that had taken place in language, of the early phases of the family, of
+religion, of property, had all favoured the revival of the Heraclitean
+view:  panta rei.  As to the categories of political economy, it was soon
+to be recognised, as by Lassalle, that they too are only historical.  The
+philosophy of history, moreover, gave expression under various forms to the
+same tendency.  Hegel declares that "all that is real is rational," but at
+the same time he shows that all that is real is ephemeral, and that for
+history there is nothing fixed beneath the sun.  It is this sense of
+universal evolution that Darwin came with fresh authority to enlarge.  It
+was in the name of biological facts themselves that he taught us to see
+only slow metamorphoses in the history of institutions, and to be always on
+the outlook for survivals side by side with rudimentary forms.  Anyone who
+reads "Primitive Culture", by Tylor,--a writer closely connected with
+Darwin--will be able to estimate the services which these cardinal ideas
+were to render to the social sciences when the age of comparative research
+had succeeded to that of a priori construction.
+
+Let us note, moreover, that the philosophy of Becoming in passing through
+the Darwinian biology became, as it were, filtered:  it got rid of those
+traces of finalism, which, under different forms, it had preserved through
+all the systems of German Romanticism.  Even in Herbert Spencer, it has
+been plausibly argued, one can detect something of that sort of mystic
+confidence in forces spontaneously directing life, which forms the very
+essence of those systems.  But Darwin's observations were precisely
+calculated to render such an hypothesis futile.  At first people may have
+failed to see this; and we call to mind the ponderous sarcasms of Flourens
+when he objected to the theory of Natural Selection that it attributed to
+nature a power of free choice.  "Nature endowed with will!  That was the
+final error of last century; but the nineteenth no longer deals in
+personifications."  (P. Flourens, "Examen du Livre de M. Darwin sur
+l'Origine des Especes", page 53, Paris, 1864.  See also Huxley, "Criticisms
+on the 'Origin of Species'", "Collected Essays", Vol. II, page 102, London,
+1902.)  In fact Darwin himself put his readers on their guard against the
+metaphors he was obliged to use.  The processes by which he explains the
+survival of the fittest are far from affording any indication of the design
+of some transcendent breeder.  Nor, if we look closely, do they even imply
+immanent effort in the animal; the sorting out can be brought about
+mechanically, simply by the action of the environment.  In this connection
+Huxley could with good reason maintain that Darwin's originality consisted
+in showing how harmonies which hitherto had been taken to imply the agency
+of intelligence and will could be explained without any such intervention. 
+So, when later on, objective sociology declares that, even when social
+phenomena are in question, all finalist preconceptions must be distrusted
+if a science is to be constituted, it is to Darwin that its thanks are due;
+he had long been clearing paths for it which lay well away from the old
+familiar road trodden by so many theories of evolution.
+
+This anti-finalist doctrine, when fully worked out, was, moreover,
+calculated to aid in the needful dissociation of two notions:  that of
+evolution and that of progress.  In application to society these had long
+been confounded; and, as a consequence, the general idea seemed to be that
+only one type of evolution was here possible.  Do we not detect such a view
+in Comte's sociology, and perhaps even in Herbert Spencer's?  Whoever,
+indeed, assumes an end for evolution is naturally inclined to think that
+only one road leads to that end.  But those whose minds the Darwinian
+theory has enlightened are aware that the transformations of living beings
+depend primarily upon their conditions, and that it is these conditions
+which are the agents of selection from among individual variations.  Hence,
+it immediately follows that transformations are not necessarily
+improvements.  Here, Darwin's thought hesitated.  Logically his theory
+proves, as Ray Lankester pointed out, that the struggle for existence may
+have as its outcome degeneration as well as amelioration:  evolution may be
+regressive as well as progressive.  Then, too--and this is especially to be
+borne in mind--each species takes its good where it finds it, seeks its own
+path and survives as best it can.  Apply this notion to society and you
+arrive at the theory of multilinear evolution.  Divergencies will no longer
+surprise you.  You will be forewarned not to apply to all civilisations the
+same measure of progress, and you will recognise that types of evolution
+may differ just as social species themselves differ.  Have we not here one
+of the conceptions which mark off sociology proper from the old philosophy
+of history?
+
+But if we are to estimate the influence of Darwinism upon sociological
+conceptions, we must not dwell only upon the way in which Darwin impressed
+the general notion of evolution upon the minds of thinkers.  We must go
+into details.  We must consider the influence of the particular theories by
+which he explained the mechanism of this evolution.  The name of the author
+of "The Origin of Species" has been especially attached, as everyone knows,
+to the doctrines of "natural selection" and of "struggle for existence,"
+completed by the notion of "individual variation."  These doctrines were
+turned to account by very different schools of social philosophy. 
+Pessimistic and optimistic, aristocratic and democratic, individualistic
+and socialistic systems were to war with each other for years by casting
+scraps of Darwinism at each other's heads.
+
+It was the spectacle of human contrivance that suggested to Darwin his
+conception of natural selection.  It was in studying the methods of pigeon
+breeders that he divined the processes by which nature, in the absence of
+design, obtains analogous results in the differentiation of types.  As soon
+as the importance of artificial selection in the transformation of species
+of animals was understood, reflection naturally turned to the human
+species, and the question arose, How far do men observe, in connection with
+themselves, those laws of which they make practical application in the case
+of animals?  Here we come upon one of the ideas which guided the researches
+of Galton, Darwin's cousin.  The author of "Inquiries into Human Faculty
+and its Development" ("Inquiries into Human Faculty", pages 1, 2, 3 sq.,
+London, 1883.), has often expressed his surprise that, considering all the
+precautions taken, for example, in the breeding of horses, none whatever
+are taken in the breeding of the human species.  It seems to be forgotten
+that the species suffers when the "fittest" are not able to perpetuate
+their type.  Ritchie, in his "Darwinism and Politics" ("Darwinism and
+Politics" pages 9, 22, London, 1889.) reminds us of Darwin's remark that
+the institution of the peerage might be defended on the ground that peers,
+owing to the prestige they enjoy, are enabled to select as wives "the most
+beautiful and charming women out of the lower ranks."  ("Life and Letters
+of Charles Darwin", II. page 385.)  But, says Galton, it is as often as not
+"heiresses" that they pick out, and birth statistics seem to show that
+these are either less robust or less fecund than others.  The truth is that
+considerations continue to preside over marriage which are entirely foreign
+to the improvement of type, much as this is a condition of general
+progress.  Hence the importance of completing Odin's and De Candolle's
+statistics which are designed to show how characters are incorporated in
+organisms, how they are transmitted, how lost, and according to what law
+eugenic elements depart from the mean or return to it.
+
+But thinkers do not always content themselves with undertaking merely the
+minute researches which the idea of Selection suggests.  They are eager to
+defend this or that thesis.  In the name of this idea certain social
+anthropologists have recast the conception of the process of civilisation,
+and have affirmed that Social Selection generally works against the trend
+of Natural Selection.  Vacher de Lapouge--following up an observation by
+Broca on the point--enumerates the various institutions, or customs, such
+as the celibacy of priests and military conscription, which cause
+elimination or sterilisation of the bearers of certain superior qualities,
+intellectual or physical.  In a more general way he attacks the democratic
+movement, a movement, as P. Bourget says, which is "anti-physical" and
+contrary to the natural laws of progress; though it has been inspired "by
+the dreams of that most visionary of all centuries, the eighteenth."  (V.
+de Lapouge, "Les Selections sociales", page 259, Paris, 1896.)  The
+"Equality" which levels down and mixes (justly condemned, he holds, by the
+Comte de Gobineau), prevents the aristocracy of the blond dolichocephales
+from holding the position and playing the part which, in the interests of
+all, should belong to them.  Otto Ammon, in his "Natural Selection in Man",
+and in "The Social Order and its Natural Bases" ("Die naturliche Auslese
+beim Menschen", Jena, 1893; "Die Gesellschaftsordnung und ihre naturlichen
+Grundlagen".  "Entwurf einer Sozialanthropologie", Jena, 1896.), defended
+analogous doctrines in Germany; setting the curve representing frequency of
+talent over against that of income, he attempted to show that all
+democratic measures which aim at promoting the rise in the social scale of
+the talented are useless, if not dangerous; that they only increase the
+panmixia, to the great detriment of the species and of society.
+
+Among the aristocratic theories which Darwinism has thus inspired we must
+reckon that of Nietzsche.  It is well known that in order to complete his
+philosophy he added biological studies to his philological; and more than
+once in his remarks upon the "Wille zur Macht" he definitely alludes to
+Darwin; though it must be confessed that it is generally in order to
+proclaim the in sufficiency of the processes by which Darwin seeks to
+explain the genesis of species.  Nevertheless, Nietzsche's mind is
+completely possessed by an ideal of Selection.  He, too, has a horror of
+panmixia.  The naturalists' conception of "the fittest" is joined by him to
+that of the "hero" of romance to furnish a basis for his doctrine of the
+Superman.  Let us hasten to add, moreover, that at the very moment when
+support was being sought in the theory of Selection for the various forms
+of the aristocratic doctrine, those same forms were being battered down on
+another side by means of that very theory.  Attention was drawn to the fact
+that by virtue of the laws which Darwin himself had discovered isolation
+leads to etiolation.  There is a risk that the privilege which withdraws
+the privileged elements of Society from competition will cause them to
+degenerate.  In fact, Jacoby in his "Studies in Selection, in connexion
+with Heredity in Man", ("Etudes sur la Selection dans ses rapports avec
+l'heredite chez l'homme", Paris, page 481, 1881.), concludes that
+"sterility, mental debility, premature death and, finally, the extinction
+of the stock were not specially and exclusively the fate of sovereign
+dynasties; all privileged classes, all families in exclusively elevated
+positions share the fate of reigning families, although in a minor degree
+and in direct proportion to the loftiness of their social standing.  From
+the mass of human beings spring individuals, families, races, which tend to
+raise themselves above the common level; painfully they climb the rugged
+heights, attain the summits of power, of wealth, of intelligence, of
+talent, and then, no sooner are they there than they topple down and
+disappear in gulfs of mental and physical degeneracy."  The demographical
+researches of Hansen ("Die drei Bevolkerungsstufen", Munich, 1889.)
+(following up and completing Dumont's) tended, indeed, to show that urban
+as well as feudal aristocracies, burgher classes as well as noble castes,
+were liable to become effete.  Hence it might well be concluded that the
+democratic movement, operating as it does to break down class barriers, was
+promoting instead of impeding human selection.
+
+So we see that, according to the point of view, very different conclusions
+have been drawn from the application of the Darwinian idea of Selection to
+human society.  Darwin's other central idea, closely bound up with this,
+that, namely, of the "struggle for existence" also has been diversely
+utilised.  But discussion has chiefly centered upon its signification.  And
+while some endeavour to extend its application to everything, we find
+others trying to limit its range.  The conception of a "struggle for
+existence" has in the present day been taken up into the social sciences
+from natural science, and adopted.  But originally it descended from social
+science to natural.  Darwin's law is, as he himself said, only Malthus' law
+generalised and extended to the animal world:  a growing disproportion
+between the supply of food and the number of the living is the fatal order
+whence arises the necessity of universal struggle, a struggle which, to the
+great advantage of the species, allows only the best equipped individuals
+to survive.  Nature is regarded by Huxley as an immense arena where all
+living beings are gladiators.  ("Evolution and Ethics", page 200;
+"Collected Essays", Vol. IX, London, 1894.)
+
+Such a generalisation was well adapted to feed the stream of pessimistic
+thought; and it furnished to the apologists of war, in particular, new
+arguments, weighted with all the authority which in these days attaches to
+scientific deliverances.  If people no longer say, as Bonald did, and
+Moltke after him, that war is a providential fact, they yet lay stress on
+the point that it is a natural fact.  To the peace party Dragomirov's
+objection is urged that its attempts are contrary to the fundamental laws
+of nature, and that no sea wall can hold against breakers that come with
+such gathered force.
+
+But in yet another quarter Darwinism was represented as opposed to
+philanthropic intervention.  The defenders of the orthodox political
+economy found in it support for their tenets.  Since in the organic world
+universal struggle is the condition of progress, it seemed obvious that
+free competition must be allowed to reign unchecked in the economic world.
+Attempts to curb it were in the highest degree imprudent.  The spirit of
+Liberalism here seemed in conformity with the trend of nature:  in this
+respect, at least, contemporary naturalism, offspring of the discoveries of
+the nineteenth century, brought reinforcements to the individualist
+doctrine, begotten of the speculations of the eighteenth:  but only, it
+appeared, to turn mankind away for ever from humanitarian dreams.  Would
+those whom such conclusions repelled be content to oppose to nature's
+imperatives only the protests of the heart?  There were some who declared,
+like Brunetiere, that the laws in question, valid though they might be for
+the animal kingdom, were not applicable to the human.  And so a return was
+made to the classic dualism.  This indeed seems to be the line that Huxley
+took, when, for instance, he opposed to the cosmic process an ethical
+process which was its reverse.
+
+But the number of thinkers whom this antithesis does not satisfy grows
+daily.  Although the pessimism which claims authorisation from Darwin's
+doctrines is repugnant to them, they still are unable to accept the dualism
+which leaves a gulf between man and nature.  And their endeavour is to link
+the two by showing that while Darwin's laws obtain in both kingdoms, the
+conditions of their application are not the same:  their forms, and,
+consequently, their results, vary with the varying mediums in which the
+struggle of living beings takes place, with the means these beings have at
+disposal, with the ends even which they propose to themselves.
+
+Here we have the explanation of the fact that among determined opponents of
+war partisans of the "struggle for existence" can be found:  there are
+disciples of Darwin in the peace party.  Novicow, for example, admits the
+"combat universel" of which Le Dantec ("Les Luttes entre Societies humaines
+et leurs phases successives", Paris, 1893,) speaks; but he remarks that at
+different stages of evolution, at different stages of life the same weapons
+are not necessarily employed.  Struggles of brute force, armed hand to hand
+conflicts, may have been a necessity in the early phases of human
+societies.  Nowadays, although competition may remain inevitable and
+indispensable, it can assume milder forms.  Economic rivalries, struggles
+between intellectual influences, suffice to stimulate progress:  the
+processes which these admit are, in the actual state of civilisation, the
+only ones which attain their end without waste, the only ones logical. 
+From one end to the other of the ladder of life, struggle is the order of
+the day; but more and more as the higher rungs are reached, it takes on
+characters which are proportionately more "humane."
+
+Reflections of this kind permit the introduction into the economic order of
+limitations to the doctrine of "laisser faire, laisser passer."  This
+appeals, it is said, to the example of nature where creatures, left to
+themselves, struggle without truce and without mercy; but the fact is
+forgotten that upon industrial battlefields the conditions are different.
+The competitors here are not left simply to their natural energies:  they
+are variously handicapped.  A rich store of artificial resources exists in
+which some participate and others do not.  The sides then are unequal; and
+as a consequence the result of the struggle is falsified.  "In the animal
+world," said De Laveleye ("Le socialisme contemporain", page 384 (6th
+edition), Paris, 1891.), criticising Spencer, "the fate of each creature is
+determined by its individual qualities; whereas in civilised societies a
+man may obtain the highest position and the most beautiful wife because he
+is rich and well-born, although he may be ugly, idle or improvident; and
+then it is he who will perpetuate the species.  The wealthy man, ill
+constituted, incapable, sickly, enjoys his riches and establishes his stock
+under the protection of the laws."  Haycraft in England and Jentsch in
+Germany have strongly emphasised these "anomalies," which nevertheless are
+the rule.  That is to say that even from a Darwinian point of view all
+social reforms can readily be justified which aim at diminishing, as
+Wallace said, inequalities at the start.
+
+But we can go further still.  Whence comes the idea that all measures
+inspired by the sentiment of solidarity are contrary to Nature's trend? 
+Observe her carefully, and she will not give lessons only in individualism.
+Side by side with the struggle for existence do we not find in operation
+what Lanessan calls "association for existence."  Long ago, Espinas had
+drawn attention to "societies of animals," temporary or permanent, and to
+the kind of morality that arose in them.  Since then, naturalists have
+often insisted upon the importance of various forms of symbiosis. 
+Kropotkin in "Mutual Aid" has chosen to enumerate many examples of altruism
+furnished by animals to mankind.  Geddes and Thomson went so far as to
+maintain that "Each of the greater steps of progress is in fact associated
+with an increased measure of subordination of individual competition to
+reproductive or social ends, and of interspecific competition to co-
+operative association."  (Geddes and Thomson, "The Evolution of Sex", page
+311, London, 1889.)  Experience shows, according to Geddes, that the types
+which are fittest to surmount great obstacles are not so much those who
+engage in the fiercest competitive struggle for existence, as those who
+contrive to temper it.  From all these observations there resulted, along
+with a limitation of Darwinian pessimism, some encouragement for the
+aspirations of the collectivists.
+
+And Darwin himself would, doubtless, have subscribed to these
+rectifications.  He never insisted, like his rival, Wallace, upon the
+necessity of the solitary struggle of creatures in a state of nature, each
+for himself and against all.  On the contrary, in "The Descent of Man", he
+pointed out the serviceableness of the social instincts, and corroborated
+Bagehot's statements when the latter, applying laws of physics to politics,
+showed the great advantage societies derived from intercourse and
+communion.  Again, the theory of sexual evolution which makes the evolution
+of types depend increasingly upon preferences, judgments, mental factors,
+surely offers something to qualify what seems hard and brutal in the theory
+of natural selection.
+
+But, as often happens with disciples, the Darwinians had out-Darwined
+Darwin.  The extravagancies of social Darwinism provoked a useful reaction;
+and thus people were led to seek, even in the animal kingdom, for facts of
+solidarity which would serve to justify humane effort.
+
+On quite another line, however, an attempt has been made to connect
+socialist tendencies with Darwinian principles.  Marx and Darwin have been
+confronted; and writers have undertaken to show that the work of the German
+philosopher fell readily into line with that of the English naturalist and
+was a development of it.  Such has been the endeavour of Ferri in Italy and
+of Woltmann in Germany, not to mention others.  The founders of "scientific
+socialism" had, moreover, themselves thought of this reconciliation.  They
+make more than one allusion to Darwin in works which appeared after 1859. 
+And sometimes they use his theory to define by contrast their own ideal. 
+They remark that the capitalist system, by giving free course to individual
+competition, ends indeed in a bellum omnium contra omnes; and they make it
+clear that Darwinism, thus understood, is as repugnant to them as to
+Duhring.
+
+But it is at the scientific and not at the moral point of view that they
+place themselves when they connect their economic history with Darwin's
+work.  Thanks to this unifying hypothesis, they claim to have constructed--
+as Marx does in his preface to "Das Kapital"--a veritable natural history
+of social evolution.  Engels speaks in praise of his friend Marx as having
+discovered the true mainspring of history hidden under the veil of idealism
+and sentimentalism, and as having proclaimed in the primum vivere the
+inevitableness of the struggle for existence.  Marx himself, in "Das
+Kapital", indicated another analogy when he dwelt upon the importance of a
+general technology for the explanation of this psychology:--a history of
+tools which would be to social organs what Darwinism is to the organs of
+animal species.  And the very importance they attach to tools, to
+apparatus, to machines, abundantly proves that neither Marx nor Engels were
+likely to forget the special characters which mark off the human world from
+the animal.  The former always remains to a great extent an artificial
+world.  Inventions change the face of its institutions.  New modes of
+production revolutionise not only modes of government, but modes even of
+collective thought.  Therefore it is that the evolution of society is
+controlled by laws special to it, of which the spectacle of nature offers
+no suggestion.
+
+If, however, even in this special sphere, it can still be urged that the
+evolution of the material conditions of society is in accord with Darwin's
+theory, it is because the influence of the methods of production is itself
+to be explained by the incessant strife of the various classes with each
+other.  So that in the end Marx, like Darwin, finds the source of all
+progress in struggle.  Both are grandsons of Heraclitus:--polemos pater
+panton.  It sometimes happens, in these days, that the doctrine of
+revolutionary socialism is contrasted as rude and healthy with what may
+seem to be the enervating tendency of "solidarist" philanthropy:  the
+apologists of the doctrine then pride themselves above all upon their
+faithfulness to Darwinian principles.
+
+So far we have been mainly concerned to show the use that social
+philosophies have made of the Darwinian laws for practical purposes:  in
+order to orientate society towards their ideals each school tries to show
+that the authority of natural science is on its side.  But even in the most
+objective of theories, those which systematically make abstraction of all
+political tendencies in order to study the social reality in itself, traces
+of Darwinism are readily to be found.
+
+Let us take for example Durkheim's theory of Division of Labour ("De la
+Division du Travail social", Paris, 1893.)  The conclusions he derives from
+it are that whenever professional specialisation causes multiplication of
+distinct branches of activity, we get organic solidarity--implying
+differences--substituted for mechanical solidarity, based upon likenesses. 
+The umbilical cord, as Marx said, which connects the individual
+consciousness with the collective consciousness is cut.  The personality
+becomes more and more emancipated.  But on what does this phenomenon, so
+big with consequences, itself depend?  The author goes to social morphology
+for the answer:  it is, he says, the growing density of population which
+brings with it this increasing differentiation of activities.  But, again,
+why?  Because the greater density, in thrusting men up against each other,
+augments the intensity of their competition for the means of existence; and
+for the problems which society thus has to face differentiation of
+functions presents itself as the gentlest solution.
+
+Here one sees that the writer borrows directly from Darwin.  Competition is
+at its maximum between similars, Darwin had declared; different species,
+not laying claim to the same food, could more easily coexist.  Here lay the
+explanation of the fact that upon the same oak hundreds of different
+insects might be found.  Other things being equal, the same applies to
+society.  He who finds some unadopted speciality possesses a means of his
+own for getting a living.  It is by this division of their manifold tasks
+that men contrive not to crush each other.  Here we obviously have a
+Darwinian law serving as intermediary in the explanation of that progress
+of division of labour which itself explains so much in the social
+evolution.
+
+And we might take another example, at the other end of the series of
+sociological systems.  G. Tarde is a sociologist with the most pronounced
+anti-naturalistic views.  He has attempted to show that all application of
+the laws of natural science to society is misleading.  In his "Opposition
+Universelle" he has directly combatted all forms of sociological Darwinism.
+According to him the idea that the evolution of society can be traced on
+the same plan as the evolution of species is chimerical.  Social evolution
+is at the mercy of all kinds of inventions, which by virtue of the laws of
+imitation modify, through individual to individual, through neighbourhood
+to neighbourhood, the general state of those beliefs and desires which are
+the only "quantities" whose variation matters to the sociologist.  But, it
+may be rejoined, that however psychical the forces may be, they are none
+the less subject to Darwinian laws.  They compete with each other; they
+struggle for the mastery of minds.  Between types of ideas, as between
+organic forms, selection operates.  And though it may be that these types
+are ushered into the arena by unexpected discoveries, we yet recognise in
+the psychological accidents, which Tarde places at the base of everything,
+near relatives of those small accidental variations upon which Darwin
+builds.  Thus, accepting Tarde's own representations, it is quite possible
+to express in Darwinian terms, with the necessary transpositions, one of
+the most idealistic sociologies that have ever been constructed.
+
+These few examples suffice.  They enable us to estimate the extent of the
+field of influence of Darwinism.  It affects sociology not only through the
+agency of its advocates but through that of its opponents.  The
+questionings to which it has given rise have proved no less fruitful than
+the solutions it has suggested.  In short, few doctrines, in the history of
+social philosophy, will have produced on their passage a finer outcrop of
+ideas.
+
+
+XXIV.  THE INFLUENCE OF DARWIN UPON RELIGIOUS THOUGHT.
+
+By P.N. WAGGETT, M.A., S.S.J.E.
+
+I.
+
+The object of this paper is first to point out certain elements of the
+Darwinian influence upon Religious thought, and then to show reason for the
+conclusion that it has been, from a Christian point of view, satisfactory. 
+I shall not proceed further to urge that the Christian apologetic in
+relation to biology has been successful.  A variety of opinions may be held
+on this question, without disturbing the conclusion that the movements of
+readjustment have been beneficial to those who remain Christians, and this
+by making them more Christian and not only more liberal.  The theologians
+may sometimes have retreated, but there has been an advance of theology.  I
+know that this account incurs the charge of optimism.  It is not the worst
+that could be made.  The influence has been limited in personal range,
+unequal, even divergent, in operation, and accompanied by the appearance of
+waste and mischievous products.  The estimate which follows requires for
+due balance a full development of many qualifying considerations.  For this
+I lack space, but I must at least distinguish my view from the popular one
+that our difficulties about religion and natural science have come to an
+end.
+
+Concerning the older questions about origins--the origin of the world, of
+species, of man, of reason, conscience, religion--a large measure of
+understanding has been reached by some thoughtful men.  But meanwhile new
+questions have arisen, questions about conduct, regarding both the reality
+of morals and the rule of right action for individuals and societies.  And
+these problems, still far from solution, may also be traced to the
+influence of Darwin.  For they arise from the renewed attention to
+heredity, brought about by the search for the causes of variation, without
+which the study of the selection of variations has no sufficient basis.
+
+Even the existing understanding about origins is very far from universal. 
+On these points there were always thoughtful men who denied the necessity
+of conflict, and there are still thoughtful men who deny the possibility of
+a truce.
+
+It must further be remembered that the earlier discussion now, as I hope to
+show, producing favourable results, created also for a time grave damage,
+not only in the disturbance of faith and the loss of men--a loss not
+repaired by a change in the currents of debate--but in what I believe to be
+a still more serious respect.  I mean the introduction of a habit of facile
+and untested hypothesis in religious as in other departments of thought.
+
+Darwin is not responsible for this, but he is in part the cause of it. 
+Great ideas are dangerous guests in narrow minds; and thus it has happened
+that Darwin--the most patient of scientific workers, in whom hypothesis
+waited upon research, or if it provisionally outstepped it did so only with
+the most scrupulously careful acknowledgment--has led smaller and less
+conscientious men in natural science, in history, and in theology to an
+over-eager confidence in probable conjecture and a loose grip upon the
+facts of experience.  It is not too much to say that in many quarters the
+age of materialism was the least matter-of-fact age conceivable, and the
+age of science the age which showed least of the patient temper of inquiry.
+
+I have indicated, as shortly as I could, some losses and dangers which in a
+balanced account of Darwin's influence would be discussed at length.
+
+One other loss must be mentioned.  It is a defect in our thought which, in
+some quarters, has by itself almost cancelled all the advantages secured. 
+I mean the exaggerated emphasis on uniformity or continuity; the
+unwillingness to rest any part of faith or of our practical expectation
+upon anything that from any point of view can be called exceptional.  The
+high degree of success reached by naturalists in tracing, or reasonably
+conjecturing, the small beginnings of great differences, has led the
+inconsiderate to believe that anything may in time become anything else.
+
+It is true that this exaggeration of the belief in uniformity has produced
+in turn its own perilous reaction.  From refusing to believe whatever can
+be called exceptional, some have come to believe whatever can be called
+wonderful.
+
+But, on the whole, the discontinuous or highly various character of
+experience received for many years too little deliberate attention.  The
+conception of uniformity which is a necessity of scientific description has
+been taken for the substance of history.  We have accepted a postulate of
+scientific method as if it were a conclusion of scientific demonstration. 
+In the name of a generalisation which, however just on the lines of a
+particular method, is the prize of a difficult exploit of reflexion, we
+have discarded the direct impressions of experience; or, perhaps it is more
+true to say, we have used for the criticism of alleged experiences a
+doctrine of uniformity which is only valid in the region of abstract
+science.  For every science depends for its advance upon limitation of
+attention, upon the selection out of the whole content of consciousness of
+that part or aspect which is measurable by the method of the science. 
+Accordingly there is a science of life which rightly displays the unity
+underlying all its manifestations.  But there is another view of life,
+equally valid, and practically sometimes more important, which recognises
+the immediate and lasting effect of crisis, difference, and revolution. 
+Our ardour for the demonstration of uniformity of process and of minute
+continuous change needs to be balanced by a recognition of the catastrophic
+element in experience, and also by a recognition of the exceptional
+significance for us of events which may be perfectly regular from an
+impersonal point of view.
+
+An exorbitant jealousy of miracle, revelation, and ultimate moral
+distinctions has been imported from evolutionary science into religious
+thought.  And it has been a damaging influence, because it has taken men's
+attention from facts, and fixed them upon theories.
+
+II.
+
+With this acknowledgment of important drawbacks, requiring many words for
+their proper description, I proceed to indicate certain results of Darwin's
+doctrine which I believe to be in the long run wholly beneficial to
+Christian thought.  These are:
+
+The encouragement in theology of that evolutionary method of observation
+and study, which has shaped all modern research:
+
+The recoil of Christian apologetics towards the ground of religious
+experience, a recoil produced by the pressure of scientific criticism upon
+other supports of faith:
+
+The restatement, or the recovery of ancient forms of statement, of the
+doctrines of Creation and of divine Design in Nature, consequent upon the
+discussion of evolution and of natural selection as its guiding factor.
+
+(1)  The first of these is quite possibly the most important of all.  It
+was well defined in a notable paper read by Dr Gore, now Bishop of
+Birmingham, to the Church Congress at Shrewsbury in 1896.  We have learnt a
+new caution both in ascribing and in denying significance to items of
+evidence, in utterance or in event.  There has been, as in art, a study of
+values, which secures perspective and solidity in our representation of
+facts.  On the one hand, a given utterance or event cannot be drawn into
+evidence as if all items were of equal consequence, like sovereigns in a
+bag.  The question whence and whither must be asked, and the particular
+thing measured as part of a series.  Thus measured it is not less truly
+important, but it may be important in a lower degree.  On the other hand,
+and for exactly the same reason, nothing that is real is unimportant.  The
+"failures" are not mere mistakes.  We see them, in St Augustine's words, as
+"scholar's faults which men praise in hope of fruit."
+
+We cannot safely trace the origin of the evolutionistic method to the
+influence of natural science.  The view is tenable that theology led the
+way.  Probably this is a case of alternate and reciprocal debt.  Quite
+certainly the evolutionist method in theology, in Christian history, and in
+the estimate of scripture, has received vast reinforcement from biology, in
+which evolution has been the ever present and ever victorious conception.
+
+(2)  The second effect named is the new willingness of Christian thinkers
+to take definite account of religious experience.  This is related to
+Darwin through the general pressure upon religious faith of scientific
+criticism.  The great advance of our knowledge of organisms has been an
+important element in the general advance of science.  It has acted, by the
+varied requirements of the theory of organisms, upon all other branches of
+natural inquiry, and it held for a long time that leading place in public
+attention which is now occupied by speculative physics.  Consequently it
+contributed largely to our present estimation of science as the supreme
+judge in all matters of inquiry (F.R. Tennant:  "The Being of God in the
+light of Physical Science", in "Essays on some theological questions of the
+day".  London, 1905.), to the supposed destruction of mystery and the
+disparagement of metaphysic which marked the last age, as well as to the
+just recommendation of scientific method in branches of learning where the
+direct acquisitions of natural science had no place.
+
+Besides this, the new application of the idea of law and mechanical
+regularity to the organic world seemed to rob faith of a kind of refuge. 
+The romantics had, as Berthelot ("Evolutionisme et Platonisme", pages 45,
+46, 47.  Paris, 1908.) shows, appealed to life to redress the judgments
+drawn from mechanism.  Now, in Spencer, evolution gave us a vitalist
+mechanic or mechanical vitalism, and the appeal seemed cut off.  We may
+return to this point later when we consider evolution; at present I only
+endeavour to indicate that general pressure of scientific criticism which
+drove men of faith to seek the grounds of reassurance in a science of their
+own; in a method of experiment, of observation, of hypothesis checked by
+known facts.  It is impossible for me to do more than glance across the
+threshold of this subject.  But it is necessary to say that the method is
+in an elementary stage of revival.  The imposing success that belongs to
+natural science is absent:  we fall short of the unchallengeable unanimity
+of the Biologists on fundamentals.  The experimental method with its sure
+repetitions cannot be applied to our subject-matter.  But we have something
+like the observational method of palaeontology and geographical
+distribution; and in biology there are still men who think that the large
+examination of varieties by way of geography and the search of strata is as
+truly scientific, uses as genuinely the logical method of difference, and
+is as fruitful in sure conclusions as the quasi-chemical analysis of
+Mendelian laboratory work, of which last I desire to express my humble
+admiration.  Religion also has its observational work in the larger and
+possibly more arduous manner.
+
+But the scientific work in religion makes its way through difficulties and
+dangers.  We are far from having found the formula of its combination with
+the historical elements of our apologetic.  It is exposed, therefore, to a
+damaging fire not only from unspiritualist psychology and pathology but
+also from the side of scholastic dogma.  It is hard to admit on equal terms
+a partner to the old undivided rule of books and learning.  With Charles
+Lamb, we cry in some distress, "must knowledge come to me, if it come at
+all, by some awkward experiment of intuition, and no longer by this
+familiar process of reading?"  ("Essays of Elia", "New Year's Eve", page
+41; Ainger's edition.  London, 1899.) and we are answered that the old
+process has an imperishable value, only we have not yet made clear its
+connection with other contributions.  And all the work is young, liable to
+be drawn into unprofitable excursions, side-tracked by self-deceit and
+pretence; and it fatally attracts, like the older mysticism, the curiosity
+and the expository powers of those least in sympathy with it, ready writers
+who, with all the air of extended research, have been content with narrow
+grounds for induction.  There is a danger, besides, which accompanies even
+the most genuine work of this science and must be provided against by all
+its serious students.  I mean the danger of unbalanced introspection both
+for individuals and for societies; of a preoccupation comparable to our
+modern social preoccupation with bodily health; of reflection upon mental
+states not accompanied by exercise and growth of the mental powers; the
+danger of contemplating will and neglecting work, of analysing conviction
+and not criticising evidence.
+
+Still, in spite of dangers and mistakes, the work remains full of hopeful
+indications, and, in the best examples (Such an example is given in Baron
+F. von Hugel's recently finished book, the result of thirty years'
+research:  "The Mystical Element of Religion, as studied in Saint Catherine
+of Genoa and her Friends".  London, 1908.), it is truly scientific in its
+determination to know the very truth, to tell what we think, not what we
+think we ought to think.  (G. Tyrrell, in "Mediaevalism", has a chapter
+which is full of the important MORAL element in a scientific attitude. 
+"The only infallible guardian of truth is the spirit of truthfulness." 
+"Mediaevalism" page 182, London, 1908.), truly scientific in its employment
+of hypothesis and verification, and in growing conviction of the reality of
+its subject-matter through the repeated victories of a mastery which
+advances, like science, in the Baconian road of obedience.  It is
+reasonable to hope that progress in this respect will be more rapid and
+sure when religious study enlists more men affected by scientific desire
+and endowed with scientific capacity.
+
+The class of investigating minds is a small one, possibly even smaller than
+that of reflecting minds.  Very few persons at any period are able to find
+out anything whatever.  There are few observers, few discoverers, few who
+even wish to discover truth.  In how many societies the problems of
+philology which face every person who speaks English are left unattempted!
+And if the inquiring or the successfully inquiring class of minds is small,
+much smaller, of course, is the class of those possessing the scientific
+aptitude in an eminent degree.  During the last age this most distinguished
+class was to a very great extent absorbed in the study of phenomena, a
+study which had fallen into arrears.  For we stood possessed, in rudiment,
+of means of observation, means for travelling and acquisition, qualifying
+men for a larger knowledge than had yet been attempted.  These were now to
+be directed with new accuracy and ardour upon the fabric and behaviour of
+the world of sense.  Our debt to the great masters in physical science who
+overtook and almost out-stripped the task cannot be measured; and, under
+the honourable leadership of Ruskin, we may all well do penance if we have
+failed "in the respect due to their great powers of thought, or in the
+admiration due to the far scope of their discovery."  ("Queen of the Air",
+Preface, page vii.  London, 1906.)  With what miraculous mental energy and
+divine good fortune--as Romans said of their soldiers--did our men of
+curiosity face the apparently impenetrable mysteries of nature!  And how
+natural it was that immense accessions of knowledge, unrelated to the
+spiritual facts of life, should discredit Christian faith, by the apparent
+superiority of the new work to the feeble and unprogressive knowledge of
+Christian believers!  The day is coming when men of this mental character
+and rank, of this curiosity, this energy and this good fortune in
+investigation, will be employed in opening mysteries of a spiritual nature. 
+They will silence with masterful witness the over-confident denials of
+naturalism.  They will be in danger of the widespread recognition which
+thirty years ago accompanied every utterance of Huxley, Tyndall, Spencer. 
+They will contribute, in spite of adulation, to the advance of sober
+religious and moral science.
+
+And this result will be due to Darwin, first because by raising the dignity
+of natural science, he encouraged the development of the scientific mind;
+secondly because he gave to religious students the example of patient and
+ardent investigation; and thirdly because by the pressure of naturalistic
+criticism the religious have been driven to ascertain the causes of their
+own convictions, a work in which they were not without the sympathy of men
+of science.  (The scientific rank of its writer justifies the insertion of
+the following letter from the late Sir John Burdon-Sanderson to me.  In the
+lecture referred to I had described the methods of Professor Moseley in
+teaching Biology as affording a suggestion of the scientific treatment of
+religion.
+
+Oxford, April 30, 1902.
+
+Dear Sir,
+
+I feel that I must express to you my thanks for the discourse which I had
+the pleasure of listening to yesterday afternoon.
+
+I do not mean to say that I was able to follow all that you said as to the
+identity of Method in the two fields of Science and Religion, but I
+recognise that the "mysticism" of which you spoke gives us the only way by
+which the two fields can be brought into relation.
+
+Among much that was memorable, nothing interested me more than what you
+said of Moseley.
+
+No one, I am sure, knew better than you the value of his teaching and in
+what that value consisted.
+
+Yours faithfully
+
+J. Burdon-Sanderson.
+31-2.)
+
+In leaving the subject of scientific religious inquiry, I will only add
+that I do not believe it receives any important help--and certainly it
+suffers incidentally much damaging interruption--from the study of abnormal
+manifestations or abnormal conditions of personality.
+
+(3)  Both of the above effects seem to me of high, perhaps the very
+highest, importance to faith and to thought.  But, under the third head, I
+name two which are more directly traceable to the personal work of Darwin,
+and more definitely characteristic of the age in which his influence was
+paramount:  viz. the influence of the two conceptions of evolution and
+natural selection upon the doctrine of creation and of design respectively.
+
+It is impossible here, though it is necessary for a complete sketch of the
+matter, to distinguish the different elements and channels of this
+Darwinian influence; in Darwin's own writings, in the vigorous polemic of
+Huxley, and strangely enough, but very actually for popular thought, in the
+teaching of the definitely anti-Darwinian evolutionist Spencer.
+
+Under the head of the directly and purely Darwinian elements I should class
+as preeminent the work of Wallace and of Bates; for no two sets of facts
+have done more to fix in ordinary intelligent minds a belief in organic
+evolution and in natural selection as its guiding factor than the facts of
+geographical distribution and of protective colour and mimicry.  The facts
+of geology were difficult to grasp and the public and theologians heard
+more often of the imperfection than of the extent of the geological record.
+The witness of embryology, depending to a great extent upon microscopic
+work, was and is beyond the appreciation of persons occupied in fields of
+work other than biology.
+
+III.
+
+From the influence in religion of scientific modes of thought we pass to
+the influence of particular biological conceptions.  The former effect
+comes by way of analogy, example, encouragement and challenge; inspiring or
+provoking kindred or similar modes of thought in the field of theology; the
+latter by a collision of opinions upon matters of fact or conjecture which
+seem to concern both science and religion.
+
+In the case of Darwinism the story of this collision is familiar, and falls
+under the heads of evolution and natural selection, the doctrine of descent
+with modification, and the doctrine of its guidance or determination by the
+struggle for existence between related varieties.  These doctrines, though
+associated and interdependent, and in popular thought not only combined but
+confused, must be considered separately.  It is true that the ancient
+doctrine of Evolution, in spite of the ingenuity and ardour of Lamarck,
+remained a dream tantalising the intellectual ambition of naturalists,
+until the day when Darwin made it conceivable by suggesting the machinery
+of its guidance.  And, further, the idea of natural selection has so
+effectively opened the door of research and stimulated observation in a
+score of principal directions that, even if the Darwinian explanation
+became one day much less convincing than, in spite of recent criticism, it
+now is, yet its passing, supposing it to pass, would leave the doctrine of
+Evolution immeasurably and permanently strengthened.  For in the interests
+of the theory of selection, "Fur Darwin," as Muller wrote, facts have been
+collected which remain in any case evidence of the reality of descent with
+modification.
+
+But still, though thus united in the modern history of convictions, though
+united and confused in the collision of biological and traditional opinion,
+yet evolution and natural selection must be separated in theological no
+less than in biological estimation.  Evolution seemed inconsistent with
+Creation; natural selection with Providence and Divine design.
+
+Discussion was maintained about these points for many years and with much
+dark heat.  It ranged over many particular topics and engaged minds
+different in tone, in quality, and in accomplishment.  There was at most
+times a degree of misconception.  Some naturalists attributed to
+theologians in general a poverty of thought which belonged really to men of
+a particular temper or training.  The "timid theism" discerned in Darwin by
+so cautious a theologian as Liddon (H.P. Liddon, "The Recovery of S.
+Thomas"; a sermon preached in St Paul's, London, on April 23rd, 1882 (the
+Sunday after Darwin's death).) was supposed by many biologists to be the
+necessary foundation of an honest Christianity.  It was really more
+characteristic of devout NATURALISTS like Philip Henry Gosse, than of
+religious believers as such.  (Dr Pusey ("Unscience not Science adverse to
+Faith" 1878) writes:  "The questions as to 'species,' of what variations
+the animal world is capable, whether the species be more or fewer, whether
+accidental variations may become hereditary...and the like, naturally fall
+under the province of science.  In all these questions Mr Darwin's careful
+observations gained for him a deserved approbation and confidence.")  The
+study of theologians more considerable and even more typically conservative
+than Liddon does not confirm the description of religious intolerance given
+in good faith, but in serious ignorance, by a disputant so acute, so
+observant and so candid as Huxley.  Something hid from each other's
+knowledge the devoted pilgrims in two great ways of thought.  The truth may
+be, that naturalists took their view of what creation was from Christian
+men of science who naturally looked in their own special studies for the
+supports and illustrations of their religious belief.  Of almost every
+laborious student it may be said "Hic ab arte sua non recessit."  And both
+the believing and the denying naturalists, confining habitual attention to
+a part of experience, are apt to affirm and deny with trenchant vigour and
+something of a narrow clearness "Qui respiciunt ad pauca, de facili
+pronunciant."  (Aristotle, in Bacon, quoted by Newman in his "Idea of a
+University", page 78.  London, 1873.)
+
+Newman says of some secular teachers that "they persuade the world of what
+is false by urging upon it what is true."  Of some early opponents of
+Darwin it might be said by a candid friend that, in all sincerity of
+devotion to truth, they tried to persuade the world of what is true by
+urging upon it what is false.  If naturalists took their version of
+orthodoxy from amateurs in theology, some conservative Christians, instead
+of learning what evolution meant to its regular exponents, took their view
+of it from celebrated persons, not of the front rank in theology or in
+thought, but eager to take account of public movements and able to arrest
+public attention.
+
+Cleverness and eloquence on both sides certainly had their share in
+producing the very great and general disturbance of men's minds in the
+early days of Darwinian teaching.  But by far the greater part of that
+disturbance was due to the practical novelty and the profound importance of
+the teaching itself, and to the fact that the controversy about evolution
+quickly became much more public than any controversy of equal seriousness
+had been for many generations.
+
+We must not think lightly of that great disturbance because it has, in some
+real sense, done its work, and because it is impossible in days of more
+coolness and light, to recover a full sense of its very real difficulties.
+
+Those who would know them better should add to the calm records of Darwin
+("Life and Letters" and "More Letters of Charles Darwin".) and to the story
+of Huxley's impassioned championship, all that they can learn of George
+Romanes.  ("Life and Letters", London, 1896.  "Thoughts on Religion",
+London, 1895.  "Candid Examination of Theism", London, 1878.)  For his life
+was absorbed in this very struggle and reproduced its stages.  It began in
+a certain assured simplicity of biblical interpretation; it went on,
+through the glories and adventures of a paladin in Darwin's train, to the
+darkness and dismay of a man who saw all his most cherished beliefs
+rendered, as he thought, incredible.  ("Never in the history of man has so
+terrific a calamity befallen the race as that which all who look may now
+(viz. in consequence of the scientific victory of Darwin) behold advancing
+as a deluge, black with destruction, resistless in might, uprooting our
+most cherished hopes, engulphing our most precious creed, and burying our
+highest life in mindless destruction."--"A Candid Examination of Theism",
+page 51.)  He lived to find the freer faith for which process and purpose
+are not irreconcilable, but necessary to one another.  His development,
+scientific, intellectual and moral, was itself of high significance; and
+its record is of unique value to our own generation, so near the age of
+that doubt and yet so far from it; certainly still much in need of the
+caution and courage by which past endurance prepares men for new
+emergencies.  We have little enough reason to be sure that in the
+discussions awaiting us we shall do as well as our predecessors in theirs. 
+Remembering their endurance of mental pain, their ardour in mental labour,
+the heroic temper and the high sincerity of controversialists on either
+side, we may well speak of our fathers in such words of modesty and self-
+judgment as Drayton used when he sang the victors of Agincourt.  The
+progress of biblical study, in the departments of Introduction and
+Exegesis, resulting in the recovery of a point of view anciently tolerated
+if not prevalent, has altered some of the conditions of that discussion. 
+In the years near 1858, the witness of Scripture was adduced both by
+Christian advocates and their critics as if unmistakeably irreconcilable
+with Evolution.
+
+Huxley ("Science and Christian Tradition".  London, 1904.) found the path
+of the blameless naturalist everywhere blocked by "Moses":  the believer in
+revelation was generally held to be forced to a choice between revealed
+cosmogony and the scientific account of origins.  It is not clear how far
+the change in Biblical interpretation is due to natural science, and how
+far to the vital movements of theological study which have been quite
+independent of the controversy about species.  It belongs to a general
+renewal of Christian movement, the recovery of a heritage.  "Special
+Creation"--really a biological rather than a theological conception,--seems
+in its rigid form to have been a recent element even in English biblical
+orthodoxy.
+
+The Middle Ages had no suspicion that religious faith forbad inquiry into
+the natural origination of the different forms of life.  Bartholomaeus
+Anglicus, an English Franciscan of the thirteenth century, was a
+mutationist in his way, as Aristotle, "the Philosopher" of the Christian
+Schoolmen, had been in his.  So late as the seventeenth century, as we
+learn not only from early proceedings of the Royal Society, but from a
+writer so homely and so regularly pious as Walton, the variation of species
+and "spontaneous" generations had no theological bearing, except as
+instances of that various wonder of the world which in devout minds is food
+for devotion.
+
+It was in the eighteenth century that the harder statement took shape. 
+Something in the preciseness of that age, its exaltation of law, its cold
+passion for a stable and measured universe, its cold denial, its cold
+affirmation of the power of God, a God of ice, is the occasion of that
+rigidity of religious thought about the living world which Darwin by
+accident challenged, or rather by one of those movements of genius which,
+Goethe ("No productiveness of the highest kind...is in the power of
+anyone."--"Conversations of Goethe with Eckermann and Soret".  London,
+1850.) declares, are "elevated above all earthly control."
+
+If religious thought in the eighteenth century was aimed at a fixed and
+nearly finite world of spirit, it followed in all these respects the
+secular and critical lead.  ("La philosophie reformatrice du XVIIIe siecle
+(Berthelot, "Evolutionisme et Platonisme", Paris, 1908, page 45.) ramenait
+la nature et la societe a des mecanismes que la pensee reflechie peut
+concevoir et recomposer."  In fact, religion in a mechanical age is
+condemned if it takes any but a mechanical tone.  Butler's thought was too
+moving, too vital, too evolutionary, for the sceptics of his time.  In a
+rationalist, encyclopaedic period, religion also must give hard outline to
+its facts, it must be able to display its secret to any sensible man in the
+language used by all sensible men.  Milton's prophetic genius furnished the
+eighteenth century, out of the depth of the passionate age before it, with
+the theological tone it was to need.  In spite of the austere magnificence
+of his devotion, he gives to smaller souls a dangerous lead.  The rigidity
+of Scripture exegesis belonged to this stately but imperfectly sensitive
+mode of thought.  It passed away with the influence of the older
+rationalists whose precise denials matched the precise and limited
+affirmations of the static orthodoxy.
+
+I shall, then, leave the specially biblical aspect of the debate--
+interesting as it is and even useful, as in Huxley's correspondence with
+the Duke of Argyll and others in 1892 ("Times", 1892, passim.)--in order to
+consider without complication the permanent elements of Christian thought
+brought into question by the teaching of evolution.
+
+Such permanent elements are the doctrine of God as Creator of the universe,
+and the doctrine of man as spiritual and unique.  Upon both the doctrine of
+evolution seemed to fall with crushing force.
+
+With regard to Man I leave out, acknowledging a grave omission, the
+doctrine of the Fall and of Sin.  And I do so because these have not yet,
+as I believe, been adequately treated:  here the fruitful reaction to the
+stimulus of evolution is yet to come.  The doctrine of sin, indeed, falls
+principally within the scope of that discussion which has followed or
+displaced the Darwinian; and without it the Fall cannot be usefully
+considered.  For the question about the Fall is a question not merely of
+origins, but of the interpretation of moral facts whose moral reality must
+first be established.
+
+I confine myself therefore to Creation and the dignity of man.
+
+The meaning of evolution, in the most general terms, is that the
+differentiation of forms is not essentially separate from their behaviour
+and use; that if these are within the scope of study, that is also; that
+the world has taken the form we see by movements not unlike those we now
+see in progress; that what may be called proximate origins are continuous
+in the way of force and matter, continuous in the way of life, with actual
+occurrences and actual characteristics.  All this has no revolutionary
+bearing upon the question of ultimate origins.  The whole is a statement
+about process.  It says nothing to metaphysicians about cause.  It simply
+brings within the scope of observation or conjecture that series of changes
+which has given their special characters to the different parts of the
+world we see.  In particular, evolutionary science aspires to the discovery
+of the process or order of the appearance of life itself:  if it were to
+achieve its aim it could say nothing of the cause of this or indeed of the
+most familiar occurrences.  We should have become spectators or convinced
+historians of an event which, in respect of its cause and ultimate meaning,
+would be still impenetrable.
+
+With regard to the origin of species, supposing life already established,
+biological science has the well founded hopes and the measure of success
+with which we are all familiar.  All this has, it would seem, little chance
+of collision with a consistent theism, a doctrine which has its own
+difficulties unconnected with any particular view of order or process.  But
+when it was stated that species had arisen by processes through which new
+species were still being made, evolutionism came into collision with a
+statement, traditionally religious, that species were formed and fixed once
+for all and long ago.
+
+What is the theological import of such a statement when it is regarded as
+essential to belief in God?  Simply that God's activity, with respect to
+the formation of living creatures, ceased at some point in past time.
+
+"God rested" is made the touchstone of orthodoxy.  And when, under the
+pressure of the evidences, we found ourselves obliged to acknowledge and
+assert the present and persistent power of God, in the maintenance and in
+the continued formation of "types," what happened was the abolition of a
+time-limit.  We were forced only to a bolder claim, to a theistic language
+less halting, more consistent, more thorough in its own line, as well as
+better qualified to assimilate and modify such schemes as Von Hartmann's
+philosophy of the unconscious--a philosophy, by the way, quite intolerant
+of a merely mechanical evolution.  (See Von Hartmann's "Wahrheit und
+Irrthum in Darwinismus".  Berlin, 1875.)
+
+Here was not the retrenchment of an extravagant assertion, but the
+expansion of one which was faltering and inadequate.  The traditional
+statement did not need paring down so as to pass the meshes of a new and
+exacting criticism.  It was itself a net meant to surround and enclose
+experience; and we must increase its size and close its mesh to hold newly
+disclosed facts of life.  The world, which had seemed a fixed picture or
+model, gained first perspective and then solidity and movement.  We had a
+glimpse of organic HISTORY; and Christian thought became more living and
+more assured as it met the larger view of life.
+
+However unsatisfactory the new attitude might be to our critics, to
+Christians the reform was positive.  What was discarded was a limitation, a
+negation.  The movement was essentially conservative, even actually
+reconstructive.  For the language disused was a language inconsistent with
+the definitions of orthodoxy; it set bounds to the infinite, and by
+implication withdrew from the creative rule all such processes as could be
+brought within the descriptions of research.  It ascribed fixity and
+finality to that "creature" in which an apostle taught us to recognise the
+birth-struggles of an unexhausted progress.  It tended to banish mystery
+from the world we see, and to confine it to a remote first age.
+
+In the reformed, the restored, language of religion, Creation became again
+not a link in a rational series to complete a circle of the sciences, but
+the mysterious and permanent relation between the infinite and the finite,
+between the moving changes we know in part, and the Power, after the
+fashion of that observation, unknown, which is itself "unmoved all motion's
+source." (Hymn of the Church--
+  Rerum Deus tenax vigor,
+  Immotus in te permanens.)
+
+With regard to man it is hardly necessary, even were it possible, to
+illustrate the application of this bolder faith.  When the record of his
+high extraction fell under dispute, we were driven to a contemplation of
+the whole of his life, rather than of a part and that part out of sight. 
+We remembered again, out of Aristotle, that the result of a process
+interprets its beginnings.  We were obliged to read the title of such
+dignity as we may claim, in results and still more in aspirations.
+
+Some men still measure the value of great present facts in life--reason and
+virtue and sacrifice--by what a self-disparaged reason can collect of the
+meaner rudiments of these noble gifts.  Mr Balfour has admirably displayed
+the discrepancy, in this view, between the alleged origin and the alleged
+authority of reason.  Such an argument ought to be used not to discredit
+the confident reason, but to illuminate and dignify its dark beginnings,
+and to show that at every step in the long course of growth a Power was at
+work which is not included in any term or in all the terms of the series.
+
+I submit that the more men know of actual Christian teaching, its fidelity
+to the past, and its sincerity in face of discovery, the more certainly
+they will judge that the stimulus of the doctrine of evolution has produced
+in the long run vigour as well as flexibility in the doctrine of Creation
+and of man.
+
+I pass from Evolution in general to Natural Selection.
+
+The character in religious language which I have for short called
+mechanical was not absent in the argument from design as stated before
+Darwin.  It seemed to have reference to a world conceived as fixed.  It
+pointed, not to the plastic capacity and energy of living matter, but to
+the fixed adaptation of this and that organ to an unchanging place or
+function.
+
+Mr Hobhouse has given us the valuable phrase "a niche of organic
+opportunity."  Such a phrase would have borne a different sense in non-
+evolutionary thought.  In that thought, the opportunity was an opportunity
+for the Creative Power, and Design appeared in the preparation of the
+organism to fit the niche.  The idea of the niche and its occupant growing
+together from simpler to more complex mutual adjustment was unwelcome to
+this teleology.  If the adaptation was traced to the influence, through
+competition, of the environment, the old teleology lost an illustration and
+a proof.  For the cogency of the proof in every instance depended upon the
+absence of explanation.  Where the process of adaptation was discerned, the
+evidence of Purpose or Design was weak.  It was strong only when the
+natural antecedents were not discovered, strongest when they could be
+declared undiscoverable.
+
+Paley's favourite word is "Contrivance"; and for him contrivance is most
+certain where production is most obscure.  He points out the physiological
+advantage of the valvulae conniventes to man, and the advantage for
+teleology of the fact that they cannot have been formed by "action and
+pressure."  What is not due to pressure may be attributed to design, and
+when a "mechanical" process more subtle than pressure was suggested, the
+case for design was so far weakened.  The cumulative proof from the
+multitude of instances began to disappear when, in selection, a natural
+sequence was suggested in which all the adaptations might be reached by the
+motive power of life, and especially when, as in Darwin's teaching, there
+was full recognition of the reactions of life to the stimulus of
+circumstance.  "The organism fits the niche," said the teleologist,
+"because the Creator formed it so as to fit."  "The organism fits the
+niche," said the naturalist, "because unless it fitted it could not exist." 
+"It was fitted to survive," said the theologian.  "It survives because it
+fits," said the selectionist.  The two forms of statement are not
+incompatible; but the new statement, by provision of an ideally universal
+explanation of process, was hostile to a doctrine of purpose which relied
+upon evidences always exceptional however numerous.  Science persistently
+presses on to find the universal machinery of adaptation in this planet;
+and whether this be found in selection, or in direct-effect, or in vital
+reactions resulting in large changes, or in a combination of these and
+other factors, it must always be opposed to the conception of a Divine
+Power here and there but not everywhere active.
+
+For science, the Divine must be constant, operative everywhere and in every
+quality and power, in environment and in organism, in stimulus and in
+reaction, in variation and in struggle, in hereditary equilibrium, and in
+"the unstable state of species"; equally present on both sides of every
+strain, in all pressures and in all resistances, in short in the general
+wonder of life and the world.  And this is exactly what the Divine Power
+must be for religious faith.
+
+The point I wish once more to make is that the necessary readjustment of
+teleology, so as to make it depend upon the contemplation of the whole
+instead of a part, is advantageous quite as much to theology as to science.
+For the older view failed in courage.  Here again our theism was not
+sufficiently theistic.
+
+Where results seemed inevitable, it dared not claim them as God-given.  In
+the argument from Design it spoke not of God in the sense of theology, but
+of a Contriver, immensely, not infinitely wise and good, working within a
+world, the scene, rather than the ever dependent outcome, of His Wisdom;
+working in such emergencies and opportunities as occurred, by forces not
+altogether within His control, towards an end beyond Himself.  It gave us,
+instead of the awful reverence due to the Cause of all substance and form,
+all love and wisdom, a dangerously detached appreciation of an ingenuity
+and benevolence meritorious in aim and often surprisingly successful in
+contrivance.
+
+The old teleology was more useful to science than to religion, and the
+design-naturalists ought to be gratefully remembered by Biologists.  Their
+search for evidences led them to an eager study of adaptations and of
+minute forms, a study such as we have now an incentive to in the theory of
+Natural Selection.  One hardly meets with the same ardour in microscopical
+research until we come to modern workers.  But the argument from Design was
+never of great importance to faith.  Still, to rid it of this character was
+worth all the stress and anxiety of the gallant old war.  If Darwin had
+done nothing else for us, we are to-day deeply in his debt for this.  The
+world is not less venerable to us now, not less eloquent of the causing
+mind, rather much more eloquent and sacred.  But our wonder is not that
+"the underjaw of the swine works under the ground" or in any or all of
+those particular adaptations which Paley collected with so much skill, but
+that a purpose transcending, though resembling, our own purposes, is
+everywhere manifest; that what we live in is a whole, mutually sustaining,
+eventful and beautiful, where the "dead" forces feed the energies of life,
+and life sustains a stranger existence, able in some real measure to
+contemplate the whole, of which, mechanically considered, it is a minor
+product and a rare ingredient.  Here, again, the change was altogether
+positive.  It was not the escape of a vessel in a storm with loss of spars
+and rigging, not a shortening of sail to save the masts and make a port of
+refuge.  It was rather the emergence from narrow channels to an open sea. 
+We had propelled the great ship, finding purchase here and there for slow
+and uncertain movement.  Now, in deep water, we spread large canvas to a
+favouring breeze.
+
+The scattered traces of design might be forgotten or obliterated.  But the
+broad impression of Order became plainer when seen at due distance and in
+sufficient range of effect, and the evidence of love and wisdom in the
+universe could be trusted more securely for the loss of the particular
+calculation of their machinery.
+
+Many other topics of faith are affected by modern biology.  In some of
+these we have learnt at present only a wise caution, a wise uncertainty. 
+We stand before the newly unfolded spectacle of suffering, silenced; with
+faith not scientifically reassured but still holding fast certain other
+clues of conviction.  In many important topics we are at a loss.  But in
+others, and among them those I have mentioned, we have passed beyond this
+negative state and find faith positively strengthened and more fully
+expressed.
+
+We have gained also a language and a habit of thought more fit for the
+great and dark problems that remain, less liable to damaging conflicts,
+equipped for more rapid assimilation of knowledge.  And by this change
+biology itself is a gainer.  For, relieved of fruitless encounters with
+popular religion, it may advance with surer aim along the path of really
+scientific life-study which was reopened for modern men by the publication
+of "The Origin of Species".
+
+Charles Darwin regretted that, in following science, he had not done "more
+direct good" ("Life and Letters", Vol. III. page 359.) to his fellow-
+creatures.  He has, in fact, rendered substantial service to interests
+bound up with the daily conduct and hopes of common men; for his work has
+led to improvements in the preaching of the Christian faith.
+
+
+XXV.  THE INFLUENCE OF DARWINISM ON THE STUDY OF RELIGIONS.
+
+By JANE ELLEN HARRISON.
+Hon. D.Litt. (Durham), Hon. LL.D. (Aberdeen), Staff Lecturer and sometime
+Fellow of Newnham College, Cambridge.  Corresponding member of the German
+Archaeological Institute.
+
+The title of my paper might well have been "the creation by Darwinism of
+the scientific study of Religions," but that I feared to mar my tribute to
+a great name by any shadow of exaggeration.  Before the publication of "The
+Origin of Species" and "The Descent of Man", even in the eighteenth
+century, isolated thinkers, notably Hume and Herder, had conjectured that
+the orthodox beliefs of their own day were developments from the cruder
+superstitions of the past.  These were however only particular speculations
+of individual sceptics.  Religion was not yet generally regarded as a
+proper subject for scientific study, with facts to be collected and
+theories to be deduced.  A Congress of Religions such as that recently held
+at Oxford would have savoured of impiety.
+
+In the brief space allotted me I can attempt only two things; first, and
+very briefly, I shall try to indicate the normal attitude towards religion
+in the early part of the last century; second, and in more detail, I shall
+try to make clear what is the outlook of advanced thinkers to-day.  (To be
+accurate I ought to add "in Europe."  I advisedly omit from consideration
+the whole immense field of Oriental mysticism, because it has remained
+practically untouched by the influence of Darwinism.)  From this second
+inquiry it will, I hope, be abundantly manifest that it is the doctrine of
+evolution that has made this outlook possible and even necessary.
+
+The ultimate and unchallenged presupposition of the old view was that
+religion was a DOCTRINE, a body of supposed truths.  It was in fact what we
+should now call Theology, and what the ancients called Mythology.  Ritual
+was scarcely considered at all, and, when considered, it was held to be a
+form in which beliefs, already defined and fixed as dogma, found a natural
+mode of expression.  This, it will be later shown, is a profound error or
+rather a most misleading half-truth.  Creeds, doctrines, theology and the
+like are only a part, and at first the least important part, of religion.
+
+Further, and the fact is important, this DOGMA, thus supposed to be the
+essential content of the "true" religion, was a teleological scheme
+complete and unalterable, which had been revealed to man once and for all
+by a highly anthropomorphic God, whose existence was assumed.  The duty of
+man towards this revelation was to accept its doctrines and obey its
+precepts.  The notion that this revelation had grown bit by bit out of
+man's consciousness and that his business was to better it would have
+seemed rank blasphemy.  Religion, so conceived, left no place for
+development.  "The Truth" might be learnt, but never critically examined;
+being thus avowedly complete and final, it was doomed to stagnation.
+
+The details of this supposed revelation seem almost too naive for
+enumeration.  As Hume observed, "popular theology has a positive appetite
+for absurdity."  It is sufficient to recall that "revelation" included such
+items as the Creation (It is interesting to note that the very word
+"Creator" has nowadays almost passed into the region of mythology.  Instead
+we have "L'Evolution Creatrice".) of the world out of nothing in six days;
+the making of Eve from one of Adam's ribs; the Temptation by a talking
+snake; the confusion of tongues at the tower of Babel; the doctrine of
+Original Sin; a scheme of salvation which demanded the Virgin Birth,
+Vicarious Atonement, and the Resurrection of the material body.  The scheme
+was unfolded in an infallible Book, or, for one section of Christians,
+guarded by the tradition of an infallible Church, and on the acceptance or
+refusal of this scheme depended an eternity of weal or woe.  There is not
+one of these doctrines that has not now been recast, softened down,
+mysticised, allegorised into something more conformable with modern
+thinking.  It is hard for the present generation, unless their breeding has
+been singularly archaic, to realise that these amazing doctrines were
+literally held and believed to constitute the very essence of religion; to
+doubt them was a moral delinquency.
+
+It had not, however, escaped the notice of travellers and missionaries that
+savages carried on some sort of practices that seemed to be religious, and
+believed in some sort of spirits or demons.  Hence, beyond the confines
+illuminated by revealed truth, a vague region was assigned to NATURAL
+Religion.  The original revelation had been kept intact only by one chosen
+people, the Jews, by them to be handed on to Christianity.  Outside the
+borders of this Goshen the world had sunk into the darkness of Egypt. 
+Where analogies between savage cults and the Christian religions were
+observed, they were explained as degradations; the heathen had somehow
+wilfully "lost the light."  Our business was not to study but, exclusively,
+to convert them, to root out superstition and carry the torch of revelation
+to "Souls in heathen darkness lying."  To us nowadays it is a commonplace
+of anthropological research that we must seek for the beginnings of
+religion in the religions of primitive peoples, but in the last century the
+orthodox mind was convinced that it possessed a complete and luminous
+ready-made revelation; the study of what was held to be a mere degradation
+seemed idle and superfluous.
+
+But, it may be asked, if, to the orthodox, revealed religion was sacrosanct
+and savage religion a thing beneath consideration, why did not the sceptics
+show a more liberal spirit, and pursue to their logical issue the
+conjectures they had individually hazarded?  The reason is simple and
+significant.  The sceptics too had not worked free from the presupposition
+that the essence of religion is dogma.  Their intellectualism, expressive
+of the whole eighteenth century, was probably in England strengthened by
+the Protestant doctrine of an infallible Book.  Hume undoubtedly confused
+religion with dogmatic theology.  The attention of orthodox and sceptics
+alike was focussed on the truth or falsity of certain propositions.  Only a
+few minds of rare quality were able dimly to conceive that religion might
+be a necessary step in the evolution of human thought.
+
+It is not a little interesting to note that Darwin, who was leader and
+intellectual king of his generation, was also in this matter to some extent
+its child.  His attitude towards religion is stated clearly, in Chapter
+VIII. of the "Life and Letters".  (Vol. I. page 304.  For Darwin's
+religious views see also "Descent of Man", 1871, Vol. I. page 65; 2nd
+edition. Vol. I. page 142.)  On board the "Beagle" he was simply orthodox
+and was laughed at by several of the officers for quoting the Bible as an
+unanswerable authority on some point of morality.  By 1839 he had come to
+see that the Old Testament was no more to be trusted than the sacred books
+of the Hindoos.  Next went the belief in miracles, and next Paley's
+"argument from design" broke down before the law of natural selection; the
+suffering so manifest in nature is seen to be compatible rather with
+Natural Selection than with the goodness and omnipotence of God.  Darwin
+felt to the full all the ignorance that lay hidden under specious phrases
+like "the plan of creation" and "Unity of design."  Finally, he tells us
+"the mystery of the beginning of all things is insoluble by us; and I for
+one must be content to remain an Agnostic."
+
+The word Agnostic is significant not only of the humility of the man
+himself but also of the attitude of his age.  Religion, it is clear, is
+still conceived as something to be KNOWN, a matter of true or false
+OPINION. Orthodox religion was to Darwin a series of erroneous hypotheses
+to be bit by bit discarded when shown to be untenable.  The ACTS of
+religion which may result from such convictions, i.e. devotion in all its
+forms, prayer, praise, sacraments, are left unmentioned.  It is clear that
+they are not, as now to us, sociological survivals of great interest and
+importance, but rather matters too private, too personal, for discussion.
+
+Huxley, writing in the "Contemporary Review" (1871.), says, "In a dozen
+years "The Origin of Species" has worked as complete a revolution in
+biological science as the "Principia" did in astronomy."  It has done so
+because, in the words of Helmholtz, it contained "an essentially new
+creative thought," that of the continuity of life, the absence of breaks. 
+In the two most conservative subjects, Religion and Classics, this creative
+ferment was slow indeed to work.  Darwin himself felt strongly "that a man
+should not publish on a subject to which he has not given special and
+continuous thought," and hence wrote little on religion and with manifest
+reluctance, though, as already seen, in answer to pertinacious inquiry he
+gave an outline of his own views.  But none the less he foresaw that his
+doctrine must have, for the history of man's mental evolution, issues wider
+than those with which he was prepared personally to deal.  He writes, in
+"The Origin of Species" (6th edition, page 428.), "In the future I see open
+fields for far more important researches.  Psychology will be securely
+based on the foundation already well laid by Mr Herbert Spencer, that of
+the necessary acquirement of each mental power and capacity by gradation."
+
+Nowhere, it is true, does Darwin definitely say that he regarded religion
+as a set of phenomena, the development of which may be studied from the
+psychological standpoint.  Rather we infer from his PIETY--in the beautiful
+Roman sense--towards tradition and association, that religion was to him in
+some way sacrosanct.  But it is delightful to see how his heart went out
+towards the new method in religious study which he had himself, if half-
+unconsciously, inaugurated.  Writing in 1871 to Dr Tylor, on the
+publication of his "Primitive Culture", he says ("Life and Letters", Vol.
+III. page 151.), "It is wonderful how you trace animism from the lower
+races up the religious belief of the highest races.  It will make me for
+the future look at religion--a belief in the soul, etc.--from a new point
+of view."
+
+Psychology was henceforth to be based on "the necessary acquirement of each
+mental capacity by gradation."  With these memorable words the door closes
+on the old and opens on the new horizon.  The mental focus henceforth is
+not on the maintaining or refuting of an orthodoxy but on the genesis and
+evolution of a capacity, not on perfection but on process.  Continuous
+evolution leaves no gap for revelation sudden and complete.  We have
+henceforth to ask, not when was religion revealed or what was the
+revelation, but how did religious phenomena arise and develop.  For an
+answer to this we turn with new and reverent eyes to study "the heathen in
+his blindness" and the child "born in sin."  We still indeed send out
+missionaries to convert the heathen, but here at least in Cambridge before
+they start they attend lectures on anthropology and comparative religion. 
+The "decadence" theory is dead and should be buried.
+
+The study of primitive religions then has been made possible and even
+inevitable by the theory of Evolution.  We have now to ask what new facts
+and theories have resulted from that study.  This brings us to our second
+point, the advanced outlook on religion to-day.
+
+The view I am about to state is no mere personal opinion of my own.  To my
+present standpoint I have been led by the investigations of such masters as
+Drs Wundt, Lehmann, Preuss, Bergson, Beck and in our own country Drs Tylor
+and Frazer.  (I can only name here the books that have specially influenced
+my own views.  They are W. Wundt, "Volkerpsychologie", Leipzig, 1900, P.
+Beck, "Die Nachahmung", Leipzig, 1904, and "Erkenntnisstheorie des
+primitiven Denkens" in "Zeitschrift f. Philos. und Philos. Kritik", 1903,
+page 172, and 1904, page 9.  Henri Bergson, "L'Evolution Creatrice" and
+"Matiere et Memoire", 1908, K. Th. Preuss, various articles published in
+the "Globus" (see page 507, note 1), and in the "Archiv. f.
+Religionswissenschaft", and for the subject of magic, MM. Hubert et Mauss,
+"Theorie generale de la Magie", in "L'Annee Sociologique", VII.)
+
+Religion always contains two factors.  First, a theoretical factor, what a
+man THINKS about the unseen--his theology, or, if we prefer so to call it,
+his mythology.  Second, what he DOES in relation to this unseen--his
+ritual.  These factors rarely if ever occur in complete separation; they
+are blended in very varying proportions.  Religion we have seen was in the
+last century regarded mainly in its theoretical aspect as a doctrine. 
+Greek religion for example meant to most educated persons Greek mythology.
+Yet even a cursory examination shows that neither Greek nor Roman had any
+creed or dogma, any hard and fast formulation of belief.  In the Greek
+Mysteries (See my "Prolegomena to the Study of Greek Religion", page 155,
+Cambridge, 1903.) only we find what we should call a Confiteor; and this is
+not a confession of faith, but an avowal of rites performed.  When the
+religion of primitive peoples came to be examined it was speedily seen that
+though vague beliefs necessarily abound, definite creeds are practically
+non-existent.  Ritual is dominant and imperative.
+
+This predominance and priority of ritual over definite creed was first
+forced upon our notice by the study of savages, but it promptly and happily
+joined hands with modern psychology.  Popular belief says, I think,
+therefore I act; modern scientific psychology says, I act (or rather, REact
+to outside stimulus), and so I come to think.  Thus there is set going a
+recurrent series:  act and thought become in their turn stimuli to fresh
+acts and thoughts.  In examining religion as envisaged to-day it would
+therefore be more correct to begin with the practice of religion, i.e.
+ritual, and then pass to its theory, theology or mythology.  But it will be
+more convenient to adopt the reverse method.  The theoretical content of
+religion is to those of us who are Protestants far more familiar and we
+shall thus proceed from the known to the comparatively unknown.
+
+I shall avoid all attempt at rigid definition.  The problem before the
+modern investigator is, not to determine the essence and definition of
+religion but to inquire how religious phenomena, religious ideas and
+practices arose.  Now the theoretical content of religion, the domain of
+theology or mythology, is broadly familiar to all.  It is the world of the
+unseen, the supersensuous; it is the world of what we call the soul and the
+supposed objects of the soul's perception, sprites, demons, ghosts and
+gods.  How did this world grow up?
+
+We turn to our savages.  Intelligent missionaries of bygone days used to
+ply savages with questions such as these:  Had they any belief in God?  Did
+they believe in the immortality of the soul?  Taking their own clear-cut
+conceptions, discriminated by a developed terminology, these missionaries
+tried to translate them into languages that had neither the words nor the
+thoughts, only a vague, inchoate, tangled substratum, out of which these
+thoughts and words later differentiated themselves.  Let us examine this
+substratum.
+
+Nowadays we popularly distinguish between objective and subjective; and
+further, we regard the two worlds as in some sense opposed.  To the
+objective world we commonly attribute some reality independent of
+consciousness, while we think of the subjective as dependent for its
+existence on the mind.  The objective world consists of perceptible things,
+or of the ultimate constituents to which matter is reduced by physical
+speculation.  The subjective world is the world of beliefs, hallucinations,
+dreams, abstract ideas, imaginations and the like.  Psychology of course
+knows that the objective and subjective worlds are interdependent,
+inextricably intertwined, but for practical purposes the distinction is
+convenient.
+
+But primitive man has not yet drawn the distinction between objective and
+subjective.  Nay, more, it is foreign to almost the whole of ancient
+philosophy.  Plato's Ideas (I owe this psychological analysis of the
+elements of the primitive supersensuous world mainly to Dr Beck,
+"Erkenntnisstheorie des primitiven Denkens", see page 498, note 1.), his
+Goodness, Truth, Beauty, his class-names, horse, table, are it is true
+dematerialised as far as possible, but they have outside existence, apart
+from the mind of the thinker, they have in some shadowy way spatial
+extension.  Yet ancient philosophies and primitive man alike needed and
+possessed for practical purposes a distinction which served as well as our
+subjective and objective.  To the primitive savage all his thoughts, every
+object of which he was conscious, whether by perception or conception, had
+reality, that is, it had existence outside himself, but it might have
+reality of various kinds or different degrees.
+
+It is not hard to see how this would happen.  A man's senses may mislead
+him.  He sees the reflection of a bird in a pond.  To his eyes it is a real
+bird.  He touches it, HE PUTS IT TO THE TOUCH, and to his touch it is not a
+bird at all.  It is real then, but surely not quite so real as a bird that
+you can touch.  Again, he sees smoke.  It is real to his eyes.  He tries to
+grasp it, it vanishes.  The wind touches him, but he cannot see it, which
+makes him feel uncanny.  The most real thing is that which affects most
+senses and especially what affects the sense of touch.  Apparently touch is
+the deepest down, most primitive, of senses.  The rest are specialisations
+and complications.  Primitive man has no formal rubric "optical delusion,"
+but he learns practically to distinguish between things that affect only
+one sense and things that affect two or more--if he did not he would not
+survive.  But both classes of things are real to him.  Percipi est esse.
+
+So far, primitive man has made a real observation; there are things that
+appeal to one sense only.  But very soon creeps in confusion fraught with
+disaster.  He passes naturally enough, being economical of any mental
+effort, from what he really sees but cannot feel to what he thinks he sees,
+and gives to it the same secondary reality.  He has dreams, visions,
+hallucinations, nightmares.  He dreams that an enemy is beating him, and he
+wakes rubbing his head.  Then further he remembers things; that is, for
+him, he sees them.  A great chief died the other day and they buried him,
+but he sees him still in his mind, sees him in his war-paint, splendid,
+victorious.  So the image of the past goes together with his dreams and
+visions to the making of this other less real, but still real world, his
+other-world of the supersensuous, the supernatural, a world, the outside
+existence of which, independent of himself, he never questions.
+
+And, naturally enough, the future joins the past in this supersensuous
+world.  He can hope, he can imagine, he can prophesy.  And again the images
+of his hope are real; he sees them with that mind's eye which as yet he has
+not distinguished from his bodily eye.  And so the supersensuous world
+grows and grows big with the invisible present, and big also with the past
+and the future, crowded with the ghosts of the dead and shadowed with
+oracles and portents.  It is this supersensuous, supernatural world which
+is the eternity, the other-world, of primitive religion, not an endlessness
+of time, but a state removed from full sensuous reality, a world in which
+anything and everything may happen, a world peopled by demonic ancestors
+and liable to a splendid vagueness, to a "once upon a time-ness" denied to
+the present.  It not unfrequently happens that people who know that the
+world nowadays obeys fixed laws have no difficulty in believing that six
+thousand years ago man was made direct from a lump of clay, and woman was
+made from one of man's superfluous ribs.
+
+The fashioning of the supersensuous world comes out very clearly in
+primitive man's views about the soul and life after death.  Herbert Spencer
+noted long ago the influence of dreams in forming a belief in immortality,
+but being very rational himself, he extended to primitive man a quite alien
+quality of rationality.  Herbert Spencer argued that when a savage has a
+dream he seeks to account for it, and in so doing invents a spirit world. 
+The mistake here lies in the "seeks to account for it."  (Primitive man, as
+Dr Beck observes, is not impelled by an Erkenntnisstrieb.  Dr Beck says he
+has counted upwards of 30 of these mythological Triebe (tendencies) with
+which primitive man has been endowed.)  Man is at first too busy LIVING to
+have any time for disinterested THINKING.  He dreams a dream and it is real
+for him.  He does not seek to account for it any more than for his hands
+and feet.  He cannot distinguish between a CONception and a PERception,
+that is all.  He remembers his ancestors or they appear to him in a dream;
+therefore they are alive still, but only as a rule to about the third
+generation.  Then he remembers them no more and they cease to be.
+
+Next as regards his own soul.  He feels something within him, his life-
+power, his will to live, his power to act, his personality--whatever we
+like to call it.  He cannot touch this thing that is himself, but it is
+real.  His friend too is alive and one day he is dead; he cannot move, he
+cannot act.  Well, something has gone that was his friend's self.  He has
+stopped breathing.  Was it his breath? or he is bleeding; is it his blood? 
+This life-power IS something; does it live in his heart or his lungs or his
+midriff?  He did not see it go; perhaps it is like wind, an anima, a Geist,
+a ghost.  But again it comes back in a dream, only looking shadowy; it is
+not the man's life, it is a thin copy of the man; it is an "image"
+(eidolon).  It is like that shifting distorted thing that dogs the living
+man's footsteps in the sunshine; it is a "shade" (skia).  (The two
+conceptions of the soul, as a life-essence, inseparable from the body, and
+as a separable phantom seem to occur in most primitive systems.  They are
+distinct conceptions but are inextricably blended in savage thought.  The
+two notions Korperseele and Psyche have been very fully discussed in
+Wundt's "Volkerpsychologie" II. pages 1-142, Leipzig, 1900.)
+
+Ghosts and sprites, ancestor worship, the soul, oracles, prophecy; all
+these elements of the primitive supersensuous world we willingly admit to
+be the proper material of religion; but other elements are more surprising;
+such are class-names, abstract ideas, numbers, geometrical figures.  We do
+not nowadays think of these as of religious content, but to primitive men
+they were all part of the furniture of his supernatural world.
+
+With respect to class-names, Dr Tylor ("Primitive Culture", Vol. II. page
+245 (4th edition), 1903.) has shown how instructive are the first attempts
+of the savage to get at the idea of a class.  Things in which similarity is
+observed, things indeed which can be related at all are to the savage
+KINDRED.  A species is a family or a number of individuals with a common
+god to look after them.  Such for example is the Finn doctrine of the
+haltia.  Every object has its haltia, but the haltiat were not tied to the
+individual, they interested themselves in every member of the species. 
+Each stone had its haltia, but that haltia was interested in other stones;
+the individuals disappeared, the haltia remained.
+
+Nor was it only class-names that belonged to the supersensuous world.  A
+man's own proper-name is a sort of spiritual essence of him, a kind of soul
+to be carefully concealed.  By pronouncing a name you bring the thing
+itself into being.  When Elohim would create Day "he called out to the
+Light 'Day,' and to the Darkness he called out 'Night'"; the great magician
+pronounced the magic Names and the Things came into being.  "In the
+beginning was the Word" is literally true, and this reflects the fact that
+our CONCEPTUAL world comes into being by the mental process of naming. (For
+a full discussion of this point see Beck, "Nachahmung" page 41, "Die
+Sprache".)  In old times people went further; they thought that by naming
+events they could bring them to be, and custom even to-day keeps up the
+inveterate magical habit of wishing people "Good Morning" and a "Happy
+Christmas."
+
+Number, too, is part of the supersensuous world that is thoroughly
+religious.  We can see and touch seven apples, but seven itself, that
+wonderful thing that shifts from object to object, giving it its SEVENness,
+that living thing, for it begets itself anew in multiplication--surely
+seven is a fit denizen of the upper-world.  Originally all numbers dwelt
+there, and a certain supersensuous sanctity still clings to seven and
+three.  We still say "Holy, Holy, Holy," and in some mystic way feel the
+holier.
+
+The soul and the supersensuous world get thinner and thinner, rarer and
+more rarified, but they always trail behind them clouds of smoke and vapour
+from the world of sense and space whence they have come.  It is difficult
+for us even nowadays to use the word "soul" without lapsing into a sensuous
+mythology.  The Cartesians' sharp distinction between res extensa non
+cogitans and res cogitans non extansa is remote.
+
+So far then man, through the processes of his thinking, has provided
+himself with a supersensuous world, the world of sense-delusion, of smoke
+and cloud, of dream and phantom, of imagination, of name and number and
+image.  The natural course would now seem to be that this supersensuous
+world should develop into the religious world as we know it, that out of a
+vague animism with ghosts of ancestors, demons, and the like, there should
+develop in due order momentary gods (Augenblicks-Gotter), tribal gods,
+polytheism, and finally a pure monotheism.
+
+This course of development is usually assumed, but it is not I think quite
+what really happens.  The supersensuous world as we have got it so far is
+too theoretic to be complete material of religion.  It is indeed only one
+factor, or rather it is as it were a lifeless body that waits for a living
+spirit to possess and inform it.  Had the theoretic factor remained
+uninformed it would eventually have separated off into its constituent
+elements of error and truth, the error dying down as a belated metaphysic,
+the truth developing into a correct and scientific psychology of the
+subjective.  But man has ritual as well as mythology; that is, he feels and
+acts as well as thinks; nay more he probably feels and acts long before he
+definitely thinks.  This contradicts all our preconceived notions of
+theology.  Man, we imagine, believes in a god or gods and then worships. 
+The real order seems to be that, in a sense presently to be explained, he
+worships, he feels and acts, and out of his feeling and action, projected
+into his confused thinking, he develops a god.  We pass therefore to our
+second factor in religion:--ritual.
+
+The word "ritual" brings to our modern minds the notion of a church with a
+priesthood and organised services.  Instinctively we think of a
+congregation meeting to confess sins, to receive absolution, to pray, to
+praise, to listen to sermons, and possibly to partake of sacraments.  Were
+we to examine these fully developed phenomena we should hardly get further
+in the analysis of our religious conceptions than the notion of a highly
+anthropomorphic god approached by purely human methods of personal entreaty
+and adulation.
+
+Further, when we first come to the study of primitive religions we expect a
+priori to find the same elements, though in a ruder form.  We expect to see
+"The heathen in his blindness bow down to wood and stone," but the facts
+that actually confront us are startlingly dissimilar.  Bowing down to wood
+and stone is an occupation that exists mainly in the minds of hymn-writers. 
+The real savage is more actively engaged.  Instead of asking a god to do
+what he wants done, he does it or tries to do it himself; instead of
+prayers he utters spells.  In a word he is busy practising magic, and above
+all he is strenuously engaged in dancing magical dances.  When the savage
+wants rain or wind or sunshine, he does not go to church; he summons his
+tribe and they dance a rain-dance or wind-dance or sun-dance.  When a
+savage goes to war we must not picture his wife on her knees at home
+praying for the absent; instead we must picture her dancing the whole night
+long; not for mere joy of heart or to pass the weary hours; she is dancing
+his war-dance to bring him victory.
+
+Magic is nowadays condemned alike by science and by religion; it is both
+useless and impious.  It is obsolete, and only practised by malign
+sorcerers in obscure holes and corners.  Undoubtedly magic is neither
+religion nor science, but in all probability it is the spiritual protoplasm
+from which religion and science ultimately differentiated.  As such the
+doctrine of evolution bids us scan it closely.  Magic may be malign and
+private; nowadays it is apt to be both.  But in early days magic was as
+much for good as for evil; it was publicly practised for the common weal.
+
+The gist of magic comes out most clearly in magical dances.  We think of
+dancing as a light form of recreation, practised by the young from sheer
+joie de vivre and unsuitable for the mature.  But among the Tarahumares
+(Carl Lumholtz, "Unknown Mexico", page 330, London, 1903.) in Mexico the
+word for dancing, nolavoa, means "to work."  Old men will reproach young
+men saying "Why do you not go to work?" meaning why do you not dance
+instead of only looking on.  The chief religious sin of which the
+Tarahumare is conscious is that he has not danced enough and not made
+enough tesvino, his cereal intoxicant.
+
+Dancing then is to the savage WORKING, DOING, and the dance is in its
+origin an imitation or perhaps rather an intensification of processes of
+work. (Karl Bucher, "Arbeit und Rhythmus", Leipzig (3rd edition), 1902,
+passim.)  Repetition, regular and frequent, constitutes rhythm and rhythm
+heightens the sense of will power in action.  Rhythmical action may even,
+as seen in the dances of Dervishes, produce a condition of ecstasy. 
+Ecstasy among primitive peoples is a condition much valued; it is often,
+though not always, enhanced by the use of intoxicants.  Psychologically the
+savage starts from the sense of his own will power, he stimulates it by
+every means at his command.  Feeling his will strongly and knowing nothing
+of natural law he recognises no limits to his own power; he feels himself a
+magician, a god; he does not pray, he WILLS.  Moreover he wills
+collectively (The subject of collective hallucination as an element in
+magic has been fully worked out by MM. Hubert and Mauss.  "Theorie generale
+de la Magie", In "L'Annee Sociologique", 1902--3, page 140.), reinforced by
+the will and action of his whole tribe.  Truly of him it may be said "La
+vie deborde l'intelligence, l'intelligence c'est un retrecissement." 
+(Henri Bergson, "L'Evolution Creatrice", page 50.)
+
+The magical extension and heightening of personality come out very clearly
+in what are rather unfortunately known as MIMETIC dances.  Animal dances
+occur very frequently among primitive peoples.  The dancers dress up as
+birds, beasts, or fishes, and reproduce the characteristic movements and
+habits of the animals impersonated.  So characteristic is this
+impersonation in magical dancing that among the Mexicans the word for
+magic, navali, means "disguise."  K. Th. Preuss, "Archiv f. 
+Religionswissenschaft", 1906, page 97.)  A very common animal dance is the
+frog-dance.  When it rains the frogs croak.  If you desire rain you dress
+up like a frog and croak and jump.  We think of such a performance as a
+conscious imitation.  The man, we think, is more or less LIKE a frog.  That
+is not how primitive man thinks; indeed, he scarcely thinks at all; what HE
+wants done the frog can do by croaking and jumping, so he croaks and jumps
+and, for all he can, BECOMES a frog.  "L'intelligence animale JOUE sans
+doute les representations plutot qu'elle ne les pense."  (Bergson,
+"L'Evolution Creatrice", page 205.)
+
+We shall best understand this primitive state of mind if we study the child
+"born in sin."  If a child is "playing at lions" he does not IMITATE a
+lion, i.e. he does not consciously try to be a thing more or less like a
+lion, he BECOMES one.  His reaction, his terror, is the same as if the real
+lion were there.  It is this childlike power of utter impersonation, of
+BEING the thing we act or even see acted, this extension and
+intensification of our own personality that lives deep down in all of us
+and is the very seat and secret of our joy in the drama.
+
+A child's mind is indeed throughout the best clue to the understanding of
+savage magic.  A young and vital child knows no limit to his own will, and
+it is the only reality to him.  It is not that he wants at the outset to
+fight other wills, but that they simply do not exist for him.  Like the
+artist he goes forth to the work of creation, gloriously alone.  His
+attitude towards other recalcitrant wills is "they simply must."  Let even
+a grown man be intoxicated, be in love, or subject to an intense
+excitement, the limitations of personality again fall away.  Like the
+omnipotent child he is again a god, and to him all things are possible. 
+Only when he is old and weary does he cease to command fate.
+
+The Iroquois (Hewitt, "American Anthropologist", IV. I. page 32, 1902,
+N.S.) of North America have a word, orenda, the meaning of which is easier
+to describe than to define, but it seems to express the very soul of magic. 
+This orenda is your power to do things, your force, sometimes almost your
+personality.  A man who hunts well has much and good orenda; the shy bird
+who escapes his snares has a fine orenda.  The orenda of the rabbit
+controls the snow and fixes the depth to which it will fall.  When a storm
+is brewing the magician is said to be making its orenda.  When you yourself
+are in a rage, great is your orenda.  The notes of birds are utterances of
+their orenda.  When the maize is ripening, the Iroquois know it is the
+sun's heat that ripens it, but they know more; it is the cigala makes the
+sun to shine and he does it by chirping, by uttering his orenda.  This
+orenda is sometimes very like the Greek thumos, your bodily life, your
+vigour, your passion, your power, the virtue that is in you to feel and do.
+This notion of orenda, a sort of pan-vitalism, is more fluid than animism,
+and probably precedes it.  It is the projection of man's inner experience,
+vague and unanalysed, into the outer world.
+
+The mana of the Melanesians (Codrington, "The Melanesians", pages 118, 119,
+192, Oxford, 1891.) is somewhat more specialised--all men do not possess
+mana--but substantially it is the same idea.  Mana is not only a force, it
+is also an action, a quality, a state, at once a substantive, an adjective,
+and a verb.  It is very closely neighboured by the idea of sanctity. 
+Things that have mana are tabu.  Like orenda it manifests itself in noises,
+but specially mysterious ones, it is mana that is rustling in the trees. 
+Mana is highly contagious, it can pass from a holy stone to a man or even
+to his shadow if it cross the stone.  "All Melanesian religion," Dr
+Codrington says, "consists in getting mana for oneself or getting it used
+for one's benefit."  (Codrington, "The Melanesians", page 120, Oxford,
+1891.)
+
+Specially instructive is a word in use among the Omaka (See Prof. Haddon,
+"Magic and Fetishism", page 60, London, 1906.  Dr Vierkandt ("Globus",
+July, 1907, page 41) thinks that "Fernzauber" is a later development from
+Nahzauber.), wazhin-dhedhe, "directive energy, to send."  This word means
+roughly what we should call telepathy, sending out your thought or will-
+power to influence another and affect his action.  Here we seem to get
+light on what has always been a puzzle, the belief in magic exercised at a
+distance. For the savage will, distance is practically non-existent, his
+intense desire feels itself as non-spatial.  (This notion of mana, orenda,
+wazhin-dhedhe and the like lives on among civilised peoples in such words
+as the Vedic brahman in the neuter, familiar to us in its masculine form
+Brahman.  The neuter, brahman, means magic power of a rite, a rite itself,
+formula, charm, also first principle, essence of the universe.  It is own
+cousin to the Greek dunamis and phusis.  See MM. Hubert et Mauss, "Theorie
+generale de la Magie", page 117, in "L'Annee Sociologique", VII.)
+
+Through the examination of primitive ritual we have at last got at one
+tangible, substantial factor in religion, a real live experience, the
+sense, that is, of will, desire, power actually experienced in person by
+the individual, and by him projected, extended into the rest of the world.
+
+At this stage it may fairly be asked, though the question cannot with any
+certainty be answered, "at what point in the evolution of man does this
+religious experience come in?"
+
+So long as an organism reacts immediately to outside stimulus, with a
+certainty and conformity that is almost chemical, there is, it would seem,
+no place, no possibility for magical experience.  But when the germ appears
+of an intellect that can foresee an end not immediately realised, or rather
+when a desire arises that we feel and recognise as not satisfied, then
+comes in the sense of will and the impulse magically to intensify that
+will.  The animal it would seem is preserved by instinct from drawing into
+his horizon things which do not immediately subserve the conservation of
+his species.  But the moment man's life-power began to make on the outside
+world demands not immediately and inevitably realised in action (I owe this
+observation to Dr K. Th. Preuss.  He writes ("Archiv f. Relig." 1906, page
+98), "Die Betonung des Willens in den Zauberakten ist der richtige Kern. 
+In der Tat muss der Mensch den Willen haben, sich selbst und seiner
+Umgebung besondere Fahigkeiten zuzuschreiben, und den Willen hat er, sobald
+sein Verstand ihn befahigt, EINE UBER DEN INSTINKT HINAUSGEHEN DER FURSORGE
+fur sich zu zeigen.  SO LANGE IHN DER INSTINKT ALLEIN LEITET, KONNEN
+ZAUBERHANDLUNGEN NICHT ENSTEHEN."  For more detailed analysis of the origin
+of magic, see Dr Preuss "Ursprung der Religion und Kunst", "Globus",
+LXXXVI. and LXXXVII.), then a door was opened to magic, and in the train of
+magic followed errors innumerable, but also religion, philosophy, science
+and art.
+
+The world of mana, orenda, brahman is a world of feeling, desiring,
+willing, acting.  What element of thinking there may be in it is not yet
+differentiated out.  But we have already seen that a supersensuous world of
+thought grew up very early in answer to other needs, a world of sense-
+illusions, shadows, dreams, souls, ghosts, ancestors, names, numbers,
+images, a world only wanting as it were the impulse of mana to live as a
+religion.  Which of the two worlds, the world of thinking or the world of
+doing, developed first it is probably idle to inquire.  (If external
+stimuli leave on organisms a trace or record such as is known as an Engram,
+this physical basis of memory and hence of thought is almost coincident
+with reaction of the most elementary kind.  See Mr Francis Darwin's
+Presidential Address to the British Association, Dublin, 1908, page 8, and
+again Bergson places memory at the very root of conscious existence, see
+"L'Evolution Creatrice", page 18, "le fond meme de notre existence
+consciente est memoire, c'est a dire prolongation du passee dans le
+present," and again "la duree mord dans le temps et y laisse l'enpreint de
+son dent," and again, "l'Evolution implique une continuation reelle du
+passee par le present.")
+
+It is more important to ask, Why do these two worlds join?  Because, it
+would seem, mana, the egomaniac or megalomaniac element, cannot get
+satisfied with real things, and therefore goes eagerly out to a false
+world, the supersensuous other-world whose growth we have sketched.  This
+junction of the two is fact, not fancy.  Among all primitive peoples dead
+men, ghosts, spirits of all kinds, become the chosen vehicle of mana.  Even
+to this day it is sometimes urged that religion, i.e. belief in the
+immortality of the soul, is true "because it satisfies the deepest craving
+of human nature."  The two worlds, of mana and magic on the one hand, of
+ghosts and other-world on the other, combine so easily because they have
+the same laws, or rather the same comparative absence of law.  As in the
+world of dreams and ghosts, so in the world of mana, space and time offer
+no obstacles; with magic all things are possible.  In the one world what
+you imagine is real; in the other what you desire is ipso facto
+accomplished.  Both worlds are egocentric, megalomaniac, filled to the full
+with unbridled human will and desire.
+
+We are all of us born in sin, in that sin which is to science "the seventh
+and deadliest," anthropomorphism, we are egocentric, ego-projective.  Hence
+necessarily we make our gods in our own image.  Anthropomorphism is often
+spoken of in books on religion and mythology as if it were a last climax, a
+splendid final achievement in religious thought.  First, we are told, we
+have the lifeless object as god (fetichism), then the plant or animal
+(phytomorphism, theriomorphism), and last God is incarnate in the human
+form divine.  This way of putting things is misleading.  Anthropomorphism
+lies at the very beginning of our consciousness.  Man's first achievement
+in thought is to realise that there is anything at all not himself, any
+object to his subject.  When he has achieved however dimly this
+distinction, still for long, for very long he can only think of those other
+things in terms of himself; plants and animals are people with ways of
+their own, stronger or weaker than himself but to all intents and purposes
+human.
+
+Again the child helps us to understand our own primitive selves.  To
+children animals are always people.  You promise to take a child for a
+drive.  The child comes up beaming with a furry bear in her arms.  You say
+the bear cannot go.  The child bursts into tears.  You think it is because
+the child cannot endure to be separated from a toy.  It is no such thing. 
+It is the intolerable hurt done to the bear's human heart--a hurt not to be
+healed by any proffer of buns.  He wanted to go, but he was a shy, proud
+bear, and he would not say so.
+
+The relation of magic to religion has been much disputed.  According to one
+school religion develops out of magic, according to another, though they
+ultimately blend, they are at the outset diametrically opposed, magic being
+a sort of rudimentary and mistaken science (This view held by Dr Frazer is
+fully set forth in his "Golden Bough" (2nd edition), pages 73-79, London,
+1900.  It is criticised by Mr R.R. Marett in "From Spell to Prayer", "Folk-
+Lore" XI. 1900, page 132, also very fully by MM. Hubert and Mauss, "Theorie
+generale de la Magie", in "L'Annee Sociologique", VII. page 1, with Mr
+Marett's view and with that of MM. Hubert and Mauss I am in substantial
+agreement.), religion having to do from the outset with spirits.
+
+But, setting controversy aside, at the present stage of our inquiry their
+relation becomes, I think, fairly clear.  Magic is, if my view (This view
+as explained above is, I believe, my own most serious contribution to the
+subject.  In thinking it out I was much helped by Prof. Gilbert Murray.) be
+correct, the active element which informs a supersensuous world fashioned
+to meet other needs.  This blend of theory and practice it is convenient to
+call religion.  In practice the transition from magic to religion, from
+Spell to Prayer, has always been found easy.  So long as mana remains
+impersonal you order it about; when it is personified and bulks to the
+shape of an overgrown man, you drop the imperative and cringe before it. 
+"My will be done" is magic, "Thy Will be done" is the last word in
+religion.  The moral discipline involved in the second is momentous, the
+intellectual advance not striking.
+
+I have spoken of magical ritual as though it were the informing life-spirit
+without which religion was left as an empty shell.  Yet the word ritual
+does not, as normally used, convey to our minds this notion of intense
+vitalism.  Rather we associate ritual with something cut and dried, a
+matter of prescribed form and monotonous repetition.  The association is
+correct; ritual tends to become less and less informed by the life-impulse,
+more and more externalised.  Dr Beck ("Die Nachahmung und ihre Bedeutung
+fur Psychologie und Volkerkunde", Leipzig, 1904.) in his brilliant
+monograph on "Imitation" has laid stress on the almost boundless influence
+of the imitation of one man by another in the evolution of civilisation. 
+Imitation is one of the chief spurs to action.  Imitation begets custom,
+custom begets sanctity.  At first all custom is sacred.  To the savage it
+is as much a religious duty to tattoo himself as to sacrifice to his gods.
+But certain customs naturally survive, because they are really useful; they
+actually have good effects, and so need no social sanction.  Others are
+really useless; but man is too conservative and imitative to abandon them. 
+These become ritual.  Custom is cautious, but la vie est aleatoire. 
+(Bergson, op. cit. page 143.)
+
+Dr Beck's remarks on ritual are I think profoundly true and suggestive, but
+with this reservation--they are true of ritual only when uninformed by
+personal experience.  The very elements in ritual on which Dr Beck lays
+such stress, imitation, repetition, uniformity and social collectivity,
+have been found by the experience of all time to have a twofold influence--
+they inhibit the intellect, they stimulate and suggest emotion, ecstasy,
+trance.  The Church of Rome knows what she is about when she prescribes the
+telling of the rosary.  Mystery-cults and sacraments, the lineal
+descendants of magic, all contain rites charged with suggestion, with
+symbols, with gestures, with half-understood formularies, with all the
+apparatus of appeal to emotion and will--the more unintelligible they are
+the better they serve their purpose of inhibiting thought.  Thus ritual
+deadens the intellect and stimulates will, desire, emotion.  "Les
+operations magiques...sont le resultat d'une science et d'une habitude qui
+exaltent la volonte humaine au-dessus de ses limites habituelles." 
+(Eliphas Levi, "Dogme et Rituel de la haute Magie", II. page 32, Paris,
+1861, and "A defence of Magic", by Evelyn Underhill, "Fortnightly Review",
+1907.)  It is this personal EXPERIENCE, this exaltation, this sense of
+immediate, non-intellectual revelation, of mystical oneness with all
+things, that again and again rehabilitates a ritual otherwise moribund.
+
+To resume.  The outcome of our examination of ORIGINES seems to be that
+religious phenomena result from two delusive processes--a delusion of the
+non-critical intellect, a delusion of the over-confident will.  Is religion
+then entirely a delusion?  I think not.  (I am deeply conscious that what I
+say here is a merely personal opinion or sentiment, unsupported and perhaps
+unsupportable by reason, and very possibly quite worthless, but for fear of
+misunderstanding I prefer to state it.)  Every dogma religion has hitherto
+produced is probably false, but for all that the religious or mystical
+spirit may be the only way of apprehending some things and these of
+enormous importance.  It may also be that the contents of this mystical
+apprehension cannot be put into language without being falsified and
+misstated, that they have rather to be felt and lived than uttered and
+intellectually analysed, and thus do not properly fall under the category
+of true or false, in the sense in which these words are applied to
+propositions; yet they may be something for which "true" is our nearest
+existing word and are often, if not necessary at least highly advantageous
+to life.  That is why man through a series of more or less grossly
+anthropomorphic mythologies and theologies with their concomitant rituals
+tries to restate them.  Meantime we need not despair.  Serious psychology
+is yet young and has only just joined hands with physiology.  Religious
+students are still hampered by mediaevalisms such as Body and Soul, and by
+the perhaps scarcely less mythological segregations of Intellect, Emotion,
+Will.  But new facts (See the "Proceedings" of the Society for Psychical
+Research, London, passim, and especially Vols. VII.-XV.  For a valuable
+collection of the phenomena of mysticism, see William James, "Varieties of
+Religious Experience", Edinburgh, 1901-2.) are accumulating, facts about
+the formation and flux of personality, and the relations between the
+conscious and the sub-conscious.  Any moment some great imagination may
+leap out into the dark, touch the secret places of life, lay bare the
+cardinal mystery of the marriage of the spatial with the non-spatial.  It
+is, I venture to think, towards the apprehension of such mysteries, not by
+reason only, but by man's whole personality, that the religious spirit in
+the course of its evolution through ancient magic and modern mysticism is
+ever blindly yet persistently moving.
+
+Be this as it may, it is by thinking of religion in the light of evolution,
+not as a revelation given, not as a realite faite but as a process, and it
+is so only, I think, that we attain to a spirit of real patience and
+tolerance.  We have ourselves perhaps learnt laboriously something of the
+working of natural law, something of the limitations of our human will, and
+we have therefore renounced the practice of magic.  Yet we are bidden by
+those in high places to pray "Sanctify this water to the mystical washing
+away of sin."  Mystical in this connection spells magical, and we have no
+place for a god-magician:  the prayer is to us unmeaning, irreverent.  Or
+again, after much toil we have ceased, or hope we have ceased, to think
+anthropomorphically.  Yet we are invited to offer formal thanks to God for
+a meal of flesh whose sanctity is the last survival of that sacrifice of
+bulls and goats he has renounced.  Such a ritual confuses our intellect and
+fails to stir our emotion.  But to others this ritual, magical or
+anthropomorphic as it is, is charged with emotional impulse, and others, a
+still larger number, think that they act by reason when really they are
+hypnotised by suggestion and tradition; their fathers did this or that and
+at all costs they must do it.  It was good that primitive man in his youth
+should bear the yoke of conservative custom; from each man's neck that yoke
+will fall, when and because he has outgrown it.  Science teaches us to
+await that moment with her own inward and abiding patience.  Such a
+patience, such a gentleness we may well seek to practise in the spirit and
+in the memory of Darwin.
+
+
+XXVI.  EVOLUTION AND THE SCIENCE OF LANGUAGE.
+
+By P. GILES, M.A., LL.D. (Aberdeen),
+Reader in Comparative Philology in the University of Cambridge.
+
+In no study has the historical method had a more salutary influence than in
+the Science of Language.  Even the earliest records show that the meaning
+of the names of persons, places, and common objects was then, as it has
+always been since, a matter of interest to mankind.  And in every age the
+common man has regarded himself as competent without special training to
+explain by inspection (if one may use a mathematical phrase) the meaning of
+any words that attracted his attention.  Out of this amateur etymologising
+has sprung a great amount of false history, a kind of historical mythology
+invented to explain familiar names.  A single example will illustrate the
+tendency.  According to the local legend the ancestor of the Earl of
+Erroll--a husbandman who stayed the flight of his countrymen in the battle
+of Luncarty and won the victory over the Danes by the help of the yoke of
+his oxen--exhausted with the fray uttered the exclamation "Hoch heigh!" 
+The grateful king about to ennoble the victorious ploughman at once
+replied:
+
+"Hoch heigh! said ye
+And Hay shall ye be."
+
+The Norman origin of the name Hay is well-known, and the battle of Luncarty
+long preceded the appearance of Normans in Scotland, but the legend
+nevertheless persists.
+
+Though the earliest European treatise on philological questions which is
+now extant--the "Cratylus" of Plato,--as might be expected from its
+authorship, contains some acute thinking and some shrewd guesses, yet the
+work as a whole is infantine in its handling of language, and it has been
+doubted whether Plato was more than half serious in some of the suggestions
+which he puts forward.  (For an account of the "Cratylus" with references
+to other literature see Sandys' "History of Classical Scholarship", I. page
+92 ff., Cambridge, 1903.)  In the hands of the Romans things were worse
+even than they had been in the hands of Plato and his Greek successors. 
+The lack of success on the part of Varro and later Roman writers may have
+been partly due to the fact that, from the etymological point of view,
+Latin is a much more difficult language than Greek; it is by no means so
+closely connected with Greek as the ancients imagined, and they had no
+knowledge of the Celtic languages from which, on some sides at least, much
+greater light on the history of the Latin language might have been
+obtained.  Roman civilisation was a late development compared with Greek,
+and its records dating earlier than 300 B.C.--a period when the best of
+Greek literature was already in existence--are very few and scanty.  Varro
+it is true was much more of an antiquary than Plato, but his extant works
+seem to show that he was rather a "dungeon of learning" than an original
+thinker.
+
+A scientific knowledge of language can be obtained only by comparison of
+different languages of the same family and the contrasting of their
+characteristics with those of another family or other families.  It never
+occurred to the Greeks that any foreign language was worthy of serious
+study.  Herodotus and other travellers and antiquaries indeed picked up
+individual words from various languages, either as being necessary in
+communication with the inhabitants of the countries where they sojourned,
+or because of some point which interested them personally.  Plato and
+others noticed the similarity of some Phrygian words to Greek, but no
+systematic comparison seems ever to have been instituted.
+
+In the Middle Ages the treatment of language was in a sense more
+historical.  The Middle Ages started with the hypothesis, derived from the
+book of Genesis, that in the early world all men were of one language and
+of one speech.  Though on the same authority they believed that the plain
+of Shinar has seen that confusion of tongues whence sprang all the
+languages upon earth, they seem to have considered that the words of each
+separate language were nevertheless derived from this original tongue.  And
+as Hebrew was the language of the Chosen People, it was naturally assumed
+that this original tongue was Hebrew.  Hence we find Dante declaring in his
+treatise on the Vulgar Tongue (Dante "de Vulgari Eloquio", I. 4.) that the
+first word man uttered in Paradise must have been "El," the Hebrew name of
+his Maker, while as a result of the fall of Adam, the first utterance of
+every child now born into this world of sin and misery is "heu," Alas! 
+After the splendidly engraved bronze plates containing, as we now know,
+ritual regulations for certain cults, were discovered in 1444 at the town
+of Gubbio, in Umbria, they were declared, by some authorities, to be
+written in excellent Hebrew.  The study of them has been the fascination
+and the despair of many a philologist.  Thanks to the devoted labours of
+numerous scholars, mainly in the last sixty years, the general drift of
+these inscriptions is now known.  They are the only important records of
+the ancient Umbrian language, which was related closely to that of the
+Samnites and, though not so closely, to that of the Romans on the other
+side of the Apennines.  Yet less than twenty years ago a book was published
+in Germany, which boasts itself the home of Comparative Philology, wherein
+the German origin of the Umbrian language was no less solemnly demonstrated
+than had been its Celtic origin by Sir William Betham in 1842.
+
+It is good that the study of language should be historical, but the first
+requisite is that the history should be sound.  How little had been learnt
+of the true history of language a century ago may be seen from a little
+book by Stephen Weston first published in 1802 and several times reprinted,
+where accidental assonance is considered sufficient to establish
+connection.  Is there not a word "bad" in English and a word "bad" in
+Persian which mean the same thing?  Clearly therefore Persian and English
+must be connected.  The conclusion is true, but it is drawn from erroneous
+premises.  As stated, this identity has no more value than the similar
+assonance between the English "cover" and the Hebrew "kophar", where the
+history of "cover" as coming through French from a Latin "co-operire" was
+even in 1802 well-known to many.  To this day, in spite of recent elaborate
+attempts (Most recently in H. Moller's "Semitisch und Indogermanisch",
+Erster Teil, Kopenhagen, 1907.) to establish connection between the Indo-
+Germanic and the Semitic families of languages, there is no satisfactory
+evidence of such relation between these families.  This is not to deny the
+possibility of such a connection at a very early period; it is merely to
+say that through the lapse of long ages all trustworthy record of such
+relationship, if it ever existed, has been, so far as present knowledge
+extends, obliterated.
+
+But while Stephen Weston was publishing, with much public approval, his
+collection of amusing similarities between languages--similarities which
+proved nothing--the key to the historical study of at least one family of
+languages had already been found by a learned Englishman in a distant land. 
+In 1783 Sir William Jones had been sent out as a judge in the supreme court
+of judicature in Bengal.  While still a young man at Oxford he was noted as
+a linguist; his reputation as a Persian scholar had preceded him to the
+East.  In the intervals of his professional duties he made a careful study
+of the language which was held sacred by the natives of the country in
+which he was living.  He was mainly instrumental in establishing a society
+for the investigation of language and related subjects.  He was himself the
+first president of the society, and in the "third anniversary discourse"
+delivered on February 2, 1786, he made the following observations:  "The
+Sanscrit language, whatever be its antiquity, is of a wonderful structure;
+more perfect than the GREEK, more copious than the LATIN, and more
+exquisitely refined than either, yet bearing to both of them a stronger
+affinity, both in the roots of verbs and in the forms of grammar, than
+could possibly have been produced by accident; so strong indeed, that no
+philologer could examine them all three, without believing them to have
+sprung from some common source, which, perhaps, no longer exists:  there is
+a similar reason, though not quite so forcible, for supposing that both the
+Gothick and the Celtick, though blended with a very different idiom, had
+the same origin with the Sanscrit; and the old Persian might be added to
+the same family, if this was the place for discussing any question
+concerning the antiquities of Persia."  ("Asiatic Researches", I. page 422,
+"Works of Sir W. Jones", I. page 26, London, 1799.)
+
+No such epoch-making discovery was probably ever announced with less
+flourish of trumpets.  Though Sir William Jones lived for eight years more
+and delivered other anniversary discourses, he added nothing of importance
+to this utterance.  He had neither the time nor the health that was needed
+for the prosecution of so arduous an undertaking.
+
+But the good seed did not fall upon stony ground.  The news was speedily
+conveyed to Europe.  By a happy chance, the sudden renewal of war between
+France and England in 1803 gave Friedrich Schlegel the opportunity of
+learning Sanscrit from Alexander Hamilton, an Englishman who, like many
+others, was confined in Paris during the long struggle with Napoleon.  The
+influence of Schlegel was not altogether for good in the history of this
+research, but he was inspiring.  Not upon him but upon Franz Bopp, a
+struggling German student who spent some time in Paris and London a dozen
+years later, fell the mantle of Sir William Jones.  In Bopp's Comparative
+Grammar of the Indo-Germanic languages which appeared in 1833, three-
+quarters of a century ago, the foundations of Comparative Philology were
+laid.  Since that day the literature of the subject has grown till it is
+almost, if not altogether, beyond the power of any single man to cope with
+it.  But long as the discourse may be, it is but the elaboration of the
+text that Sir William Jones supplied.
+
+With the publication of Bopp's Comparative Grammar the historical study of
+language was put upon a stable footing.  Needless to say much remained to
+be done, much still remains to be done.  More than once there has been
+danger of the study following erroneous paths.  Its terminology and its
+point of view have in some degree changed.  But nothing can shake the truth
+of the statement that the Indo-Germanic languages constitute in themselves
+a family sprung from the same source, marked by the same characteristics,
+and differentiated from all other languages by formation, by vocabulary,
+and by syntax.  The historical method was applied to language long before
+it reached biology.  Nearly a quarter of a century before Charles Darwin
+was born, Sir William Jones had made the first suggestion of a comparative
+study of languages.  Bopp's Comparative Grammar began to be published nine
+years before the first draft of Darwin's treatise on the Origin of Species
+was put on paper in 1842.
+
+It is not therefore on the history of Comparative Philology in general that
+the ideas of Darwin have had most influence.  Unfortunately, as Jowett has
+said in the introduction to his translation of Plato's "Republic", most men
+live in a corner.  The specialisation of knowledge has many advantages, but
+it has also disadvantages, none worse perhaps than that it tends to narrow
+the specialist's horizon and to make it more difficult for one worker to
+follow the advances that are being made by workers in other departments. 
+No longer is it possible as in earlier days for an intellectual prophet to
+survey from a Pisgah height all the Promised Land. And the case of
+linguistic research has been specially hard.  This study has, if the
+metaphor may be allowed, a very extended frontier.  On one side it touches
+the domain of literature, on other sides it is conterminous with history,
+with ethnology and anthropology, with physiology in so far as language is
+the production of the brain and tissues of a living being, with physics in
+questions of pitch and stress accent, with mental science in so far as the
+principles of similarity, contrast, and contiguity affect the forms and the
+meanings of words through association of ideas.  The territory of
+linguistic study is immense, and it has much to supply which might be
+useful to the neighbours who border on that territory.  But they have not
+regarded her even with that interest which is called benevolent because it
+is not actively maleficent.  As Horne Tooke remarked a century ago, Locke
+had found a whole philosophy in language.  What have the philosophers done
+for language since?  The disciples of Kant and of Wilhelm von Humboldt
+supplied her plentifully with the sour grapes of metaphysics; otherwise her
+neighbours have left her severely alone save for an occasional "Ausflug,"
+on which it was clear they had sadly lost their bearings.  Some articles in
+Psychological Journals, Wundt's great work on "Volkerpsychologie" (Erster
+Band:  "Die Sprache", Leipzig, 1900.  New edition, 1904.  This work has
+been fertile in producing both opponents and supporters.  Delbruck,
+"Grundfragen der Sprachforschung", Strassburg, 1901, with a rejoinder by
+Wundt, "Sprachgeschichte" and "Sprachpsychologie", Leipzig, 1901; L.
+Sutterlin, "Das Wesen der Sprachgebilde", Heidelberg, 1902; von
+Rozwadowski, "Wortbildung und Wortbedeutung", Heidelberg, 1904; O.
+Dittrich, "Grundzuge der Sprachpsychologie", Halle, 1904, Ch. A. Sechehaye,
+"Programme et methodes de la linguistique theorique", Paris, 1908.), and
+Mauthner's brilliantly written "Beitrage zu einer Kritik der Sprache" (In
+three parts:  (i) "Sprache und Psychologie, (ii) "Zur Sprachwissenschaft",
+both Stuttgart 1901, (iii) "Zur Grammatic und Logik" (with index to all
+three volumes), Stuttgart and Berlin, 1902.) give some reason to hope that,
+on one side at least, the future may be better than the past.
+
+Where Charles Darwin's special studies came in contact with the Science of
+Language was over the problem of the origin and development of language. 
+It is curious to observe that, where so many fields of linguistic research
+have still to be reclaimed--many as yet can hardly be said to be mapped
+out,--the least accessible field of all--that of the Origin of Language--
+has never wanted assiduous tillers.  Unfortunately it is a field beyond
+most others where it may be said that
+
+"Wilding oats and luckless darnel grow."
+
+If Comparative Philology is to work to purpose here, it must be on results
+derived from careful study of individual languages and groups of languages.
+But as yet the group which Sir William Jones first mapped out and which
+Bopp organised is the only one where much has been achieved.  Investigation
+of the Semitic group, in some respects of no less moment in the history of
+civilisation and religion, where perhaps the labour of comparison is not so
+difficult, as the languages differ less among themselves, has for some
+reason strangely lagged behind.  Some years ago in the "American Journal of
+Philology" Paul Haupt pointed out that if advance was to be made, it must
+be made according to the principles which had guided the investigation of
+the Indo-Germanic languages to success, and at last a Comparative Grammar
+of an elaborate kind is in progress also for the Semitic languages. 
+(Brockelmann, "Vergleichende Grammatik der semitischen Sprachen", Berlin,
+1907 ff.  Brockelmann and Zimmern had earlier produced two small hand-
+books.  The only large work was William Wright's "Lectures on the
+Comparative Grammar of the Semitic Languages", Cambridge, 1890.)  For the
+great group which includes Finnish, Hungarian, Turkish and many languages
+of northern Asia, a beginning, but only a beginning has been made.  It may
+be presumed from the great discoveries which are in progress in Turkestan
+that presently much more will be achieved in this field.  But for a certain
+utterance to be given by Comparative Philology on the question of the
+origin of language it is necessary that not merely for these languages but
+also for those in other quarters of the globe, the facts should be
+collected, sifted and tabulated.  England rules an empire which contains a
+greater variety of languages by far than were ever held under one sway
+before.  The Government of India is engaged in producing, under the
+editorship of Dr Grierson, a linguistic survey of India, a remarkable
+undertaking and, so far as it has gone, a remarkable achievement.  Is it
+too much to ask that, with the support of the self-governing colonies, a
+similar survey should be undertaken for the whole of the British Empire?
+
+Notwithstanding the great number of books that have been written on the
+origin of language in the last three and twenty centuries, the results of
+the investigation which can be described as certain are very meagre.  The
+question originally raised was whether language came into being thesei or
+phusei, by convention or by nature.  The first alternative, in its baldest
+form at least, has passed from out the field of controversy.  No one now
+claims that names were given to living things or objects or activities by
+formal agreement among the members of an early community, or that the first
+father of mankind passed in review every living thing and gave it its name.
+Even if the record of Adam's action were to be taken literally there would
+still remain the question, whence had he this power?  Did he develop it
+himself or was it a miraculous gift with which he was endowed at his
+creation?  If the latter, then as Wundt says ("Volkerpsychologie", I. 2,
+page 585.), "the miracle of language is subsumed in the miracle of
+creation."  If Adam developed language of himself, we are carried over to
+the alternative origin of phusei.  On this hypothesis we must assume that
+the natural growth which modern theories of development regard as the
+painful progress of multitudinous generations was contracted into the
+experience of a single individual.
+
+But even if the origin of language is admitted to be NATURAL there may
+still be much variety of signification attached to the word:  NATURE, like
+most words which are used by philosophers, has accumulated many meanings,
+and as research into the natural world proceeds, is accumulating more.
+
+Forty years ago an animated controversy raged among the supporters of the
+theories which were named for short the bow-wow, the pooh-pooh and the
+ding-dong theories of the origin of language.  The third, which was the
+least tenacious of life, was made known to the English-speaking world by
+the late Professor Max Muller who, however, when questioned, repudiated it
+as his own belief.  ("Science of Thought", London, 1887, page 211.)  It was
+taken by him from Heyse's lectures on language which were published
+posthumously by Steinthal.  Put shortly the theory is that "everything
+which is struck, rings.  Each substance has its peculiar ring.  We can tell
+the more or less perfect structure of metals by their vibrations, by the
+answer which they give.  Gold rings differently from tin, wood rings
+differently from stone; and different sounds are produced according to the
+nature of each percussion.  It may be the same with man, the most highly
+organised of nature's work."  (Max Muller as above, translating from
+Heyse.)  Max Muller's repudiation of this theory was, however, not very
+whole-hearted for he proceeds later in the same argument:  "Heyse's theory,
+which I neither adopted nor rejected, but which, as will be seen, is by no
+means incompatible with that which for many years has been gaining on me,
+and which of late has been so clearly formulated by Professor Noire, has
+been assailed with ridicule and torn to pieces, often by persons who did
+not even suspect how much truth was hidden behind its paradoxical
+appearance.  We are still very far from being able to identify roots with
+nervous vibrations, but if it should appear hereafter that sensuous
+vibrations supply at least the raw material of roots, it is quite possible
+that the theory, proposed by Oken and Heyse, will retain its place in the
+history of the various attempts at solving the problem of the origin of
+language, when other theories, which in our own days were received with
+popular applause, will be completely forgotten."  ("Science of Thought",
+page 212.)
+
+Like a good deal else that has been written on the origin of language, this
+statement perhaps is not likely to be altogether clear to the plain man,
+who may feel that even the "raw material of roots" is some distance removed
+from nervous vibrations, though obviously without the existence of afferent
+and efferent nerves articulate speech would be impossible.  But Heyse's
+theory undoubtedly was that every thought or idea which occurred to the
+mind of man for the first time had its own special phonetic expression, and
+that this responsive faculty, when its object was thus fulfilled, became
+extinct.  Apart from the philosophical question whether the mind acts
+without external stimulus, into which it is not necessary to enter here, it
+is clear that this theory can neither be proved nor disproved, because it
+postulates that this faculty existed only when language first began, and
+later altogether disappeared.  As we have already seen, it is impossible
+for us to know what happened at the first beginnings of language, because
+we have no information from any period even approximately so remote; nor
+are we likely to attain it.  Even in their earliest stages the great
+families of language which possess a history extending over many centuries
+--the Indo-Germanic and the Semitic--have very little in common.  With the
+exception of Chinese, the languages which are apparently of a simpler or
+more primitive formation have either a history which, compared with that of
+the families mentioned, is very short, or, as in the case of the vast
+majority, have no history beyond the time extending only over a few years
+or, at most, a few centuries when they have been observed by competent
+scholars of European origin.  But, if we may judge by the history of
+geology and other studies, it is well to be cautious in assuming for the
+first stages of development forces which do not operate in the later,
+unless we have direct evidence of their existence.
+
+It is unnecessary here to enter into a prolonged discussion of the other
+views christened by Max Muller, not without energetic protest from their
+supporters, the bow-wow and pooh-pooh theories of language.  Suffice it to
+say that the former recognises as a source of language the imitation of the
+sounds made by animals, the fall of bodies into water or on to solid
+substances and the like, while the latter, also called the interjectional
+theory, looks to the natural ejaculations produced by particular forms of
+effort for the first beginnings of speech.  It would be futile to deny that
+some words in most languages come from imitation, and that others, probably
+fewer in number, can be traced to ejaculations.  But if either of these
+sources alone or both in combination gave rise to primitive speech, it
+clearly must have been a simple form of language and very limited in
+amount.  There is no reason to think that it was otherwise.  Presumably in
+its earliest stages language only indicated the most elementary ideas,
+demands for food or the gratification of other appetites, indications of
+danger, useful animals and plants.  Some of these, such as animals or
+indications of danger, could often be easily represented by imitative
+sounds:  the need for food and the like could be indicated by gesture and
+natural cries.  Both sources are verae causae; to them Noire, supported by
+Max Muller, has added another which has sometimes been called the Yo-heave-
+ho theory.  Noire contends that the real crux in the early stages of
+language is for primitive man to make other primitive men understand what
+he means.  The vocal signs which commend themselves to one may not have
+occurred to another, and may therefore be unintelligible.  It may be
+admitted that this difficulty exists, but it is not insuperable.  The old
+story of the European in China who, sitting down to a meal and being
+doubtful what the meat in the dish might be, addressed an interrogative
+Quack-quack? to the waiter and was promptly answered by Bow-wow,
+illustrates a simple situation where mutual understanding was easy.  But
+obviously many situations would be more complex than this, and to grapple
+with them Noire has introduced his theory of communal action.  "It was
+common effort directed to a common object, it was the most primitive
+(uralteste) labour of our ancestors, from which sprang language and the
+life of reason."  (Noire "Der Ursprung der Sprache", page 331, Mainz,
+1877.)  As illustrations of such common effort he cites battle cries, the
+rescue of a ship running on shore (a situation not likely to occur very
+early in the history of man), and others.  Like Max Muller he holds that
+language is the utterance and the organ of thought for mankind, the one
+characteristic which separates man from the brute.  "In common action the
+word was first produced; for long it was inseparably connected with action;
+through long-continued connection it gradually became the firm,
+intelligible symbol of action, and then in its development indicated also
+things of the external world in so far as the action affected them and
+finally the sound began to enter into a connexion with them also."  (Op.
+cit. page 339.)  In so far as this theory recognises language as a social
+institution it is undoubtedly correct.  Darwin some years before Noire had
+pointed to the same social origin of language in the fourth chapter of his
+work on "The Expression of the Emotions in Man and Animals".  "Naturalists
+have remarked, I believe with truth, that social animals, from habitually
+using their vocal organs as a means of intercommunication, use them on
+other occasions much more freely than other animals...The principle, also,
+of association, which is so widely extended in its power, has likewise
+played its part.  Hence it allows that the voice, from having been employed
+as a serviceable aid under certain conditions, inducing pleasure, pain,
+rage, etc., is commonly used whenever the same sensations or emotions are
+excited, under quite different conditions, or in a lesser degree."  ("The
+Expression of the Emotions", page 84 (Popular Edition, 1904).
+
+Darwin's own views on language which are set forth most fully in "The
+Descent of Man" (page 131 ff. (Popular Edition, 1906).) are characterised
+by great modesty and caution.  He did not profess to be a philologist and
+the facts are naturally taken from the best known works of the day (1871).
+In the notes added to the second edition he remarks on Max Muller's denial
+of thought without words, "what a strange definition must here be given to
+the word thought!"  (Op. cit. page 135, footnote 63.)  He naturally finds
+the origin of language in "the imitation and modification of various
+natural sounds, the voices of other animals, and man's own instinctive
+cries aided by signs and gestures (op. cit. page 132.)...As the voice was
+used more and more, the vocal organs would have been strengthened and
+perfected through the principle of the inherited effects of use; and this
+would have reacted on the power of speech."  (Op. cit. page 133.)  On man's
+own instinctive cries, he has more to say in "The Expression of the
+Emotions".  (Page 93 (Popular Edition, 1904) and elsewhere.)  These remarks
+have been utilised by Prof. Jespersen of Copenhagen in propounding an
+ingenious theory of his own to the effect that speech develops out of
+singing.  ("Progress in Language", page 361, London, 1894.)
+
+For many years and in many books Max Muller argued against Darwin's views
+on evolution on the one ground that thought is impossible without speech;
+consequently as speech is confined to the human race, there is a gulf which
+cannot be bridged between man and all other creatures.  (Some interesting
+comments on the theory will be found in a lecture on "Thought and Language"
+in Samuel Butler's "Essays on Life, Art and Science", London, 1908.)  On
+the title-page of his "Science of Thought" he put the two sentences "No
+Reason without Language:  No Language without Reason."  It may be readily
+admitted that the second dictum is true, that no language properly so-
+called can exist without reason.  Various birds can learn to repeat words
+or sentences used by their masters or mistresses.  In most cases probably
+the birds do not attach their proper meaning to the words they have learnt;
+they repeat them in season and out of season, sometimes apparently for
+their own amusement, generally in the expectation, raised by past
+experience, of being rewarded for their proficiency.  But even here it is
+difficult to prove a universal negative, and most possessors of such pets
+would repudiate indignantly the statement that the bird did not understand
+what was said to it, and would also contend that in many cases the words
+which it used were employed in their ordinary meaning.  The first dictum
+seems to be inconsistent with fact.  The case of deaf mutes, such as Laura
+Bridgeman, who became well educated, or the still more extraordinary case
+of Helen Keller, deaf, dumb, and blind, who in spite of these disadvantages
+has learnt not only to reason but to reason better than the average of
+persons possessed of all their senses, goes to show that language and
+reason are not necessarily always in combination.  Reason is but the
+conscious adaptation of means to ends, and so defined is a faculty which
+cannot be denied to many of the lower animals.  In these days when so many
+books on Animal Intelligence are issued from the press, it seems
+unnecessary to labour the point.  Yet none of these animals, except by
+parrot-imitation, makes use of speech, because man alone possesses in a
+sufficient degree of development the centres of nervous energy which are
+required for the working of articulation in speech.  On this subject much
+investigation was carried on during the last years of Darwin's life and
+much more in the period since his death.  As early as 1861 Broca, following
+up observations made by earlier French writers, located the centre of
+articulate speech in the third left frontal convolution of the brain.  In
+1876 he more definitely fixed the organ of speech in "the posterior two-
+fifths of the third frontal convolution" (Macnamara, "Human Speech", page
+197, London, 1908.), both sides and not merely the left being concerned in
+speech production.  Owing however to the greater use by most human beings
+of the right side of the body, the left side of the brain, which is the
+motor centre for the right side of the body, is more highly developed than
+its right side, which moves the left side of the body.  The investigations
+of Professors Ferrier, Sherrington and Grunbaum have still more precisely
+defined the relations between brain areas and certain groups of muscles. 
+One form of aphasia is the result of injury to or disease in the third
+frontal convolution because the motor centre is no longer equal to the task
+of setting the necessary muscles in motion.  In the brain of idiots who are
+unable to speak, the centre for speech is not developed.  (Op. cit. page
+226.)  In the anthropoid apes the brain is similarly defective, though it
+has been demonstrated by Professors Cunningham and Marchand "that there is
+a tendency, especially in the gorilla's brain, for the third frontal
+convolution to assume the human form...But if they possessed a centre for
+speech, those parts of the hemispheres of their brains which form the
+mechanism by which intelligence is elaborated are so ill-developed, as
+compared with the rest of their bodies, that we can not conceive, even with
+more perfect frontal convolutions, that these animals could formulate ideas
+expressible in intelligent speech."  (Op. cit. page 223.)
+
+While Max Muller's theory is Shelley's
+
+"He gave man speech, and speech created thought,
+Which is the measure of the universe" ("Prometheus Unbound" II. 4.),
+
+it seems more probable that the development was just the opposite--that the
+development of new activities originated new thoughts which required new
+symbols to express them, symbols which may at first have been, even to a
+greater extent than with some of the lower races at present, sign language
+as much as articulation.  When once the faculty of articulation was
+developed, which, though we cannot trace the process, was probably a very
+gradual growth, there is no reason to suppose that words developed in any
+other way then they do at present.  An erroneous notion of the development
+of language has become widely spread through the adoption of the
+metaphorical term "roots" for the irreducible elements of human speech. 
+Men never talked in roots; they talked in words.  Many words of kindred
+meaning have a part in common, and a root is nothing but that common part
+stripped of all additions.  In some cases it is obvious that one word is
+derived from another by the addition of a fresh element; in other cases it
+is impossible to say which of two kindred words is the more primitive.  A
+root is merely a convenient term for an abstraction.  The simplest word may
+be called a root, but it is nevertheless a word.  How are new words added
+to a language in the present day?  Some communities, like the Germans,
+prefer to construct new words for new ideas out of the old material
+existing in the language; others, like the English, prefer to go to the
+ancient languages of Greece and Rome for terms to express new ideas.  The
+same chemical element is described in the two languages as sour stuff
+(Sauerstoff) and as oxygen.  Both terms mean the same thing etymologically
+as well as in fact.  On behalf of the German method, it may be contended
+that the new idea is more closely attached to already existing ideas, by
+being expressed in elements of the language which are intelligible even to
+the meanest capacity.  For the English practice it may be argued that, if
+we coin a new word which means one thing, and one thing only, the idea
+which it expresses is more clearly defined than if it were expressed in
+popularly intelligible elements like "sour stuff."  If the etymological
+value of words were always present in the minds of their users, "oxygen"
+would undoubtedly have an advantage over "sour stuff" as a technical term. 
+But the tendency in language is to put two words of this kind which express
+but one idea under a single accent, and when this has taken place, no one
+but the student of language any longer observes what the elements really
+mean.  When the ordinary man talks of a "blackbird" it is certainly not
+present to his consciousness that he is talking of a black bird, unless for
+some reason conversation has been dwelling upon the colour rather than
+other characteristics of the species.
+
+But, it may be said, words like "oxygen" are introduced by learned men, and
+do not represent the action of the man in the street, who, after all, is
+the author of most additions to the stock of human language.  We may go
+back therefore some four centuries to a period, when scientific study was
+only in its infancy, and see what process was followed.  With the discovery
+of America new products never seen before reached Europe, and these
+required names.  Three of the most characteristic were tobacco, the potato,
+and the turkey.  How did these come to be so named?  The first people to
+import these products into Europe were naturally the Spanish discoverers. 
+The first of these words--tobacco--appears in forms which differ only
+slightly in the languages of all civilised countries:  Spanish tabaco,
+Italian tabacco, French tabac, Dutch and German tabak, Swedish tobak, etc. 
+The word in the native dialect of Hayti is said to have been tabaco, but to
+have meant not the plant (According to William Barclay, "Nepenthes, or the
+Virtue of Tobacco", Edinburgh, 1614, "the countrey which God hath honoured
+and blessed with this happie and holy herbe doth call it in their native
+language 'Petum'.") but the pipe in which it was smoked.  It thus
+illustrates a frequent feature of borrowing--that the word is not borrowed
+in its proper signification, but in some sense closely allied thereto,
+which a foreigner, understanding the language with difficulty, might
+readily mistake for the real meaning.  Thus the Hindu practice of burning a
+wife upon the funeral pyre of her husband is called in English "suttee",
+this word being in fact but the phonetic spelling of the Sanskrit "sati",
+"a virtuous woman," and passing into its English meaning because formerly
+the practice of self-immolation by a wife was regarded as the highest
+virtue.
+
+The name of the potato exhibits greater variety.  The English name was
+borrowed from the Spanish "patata", which was itself borrowed from a native
+word for the "yam" in the dialect of Hayti.  The potato appeared early in
+Italy, for the mariners of Genoa actively followed the footsteps of their
+countryman Columbus in exploring America.  In Italian generally the form
+"patata" has survived.  The tubers, however, also suggested a resemblance
+to truffles, so that the Italian word "tartufolo", a diminutive of the
+Italian modification of the Latin "terrae tuber" was applied to them.  In
+the language of the Rhaetian Alps this word appears as "tartufel".  From
+there it seems to have passed into Germany where potatoes were not
+cultivated extensively till the eighteenth century, and "tartufel" has in
+later times through some popular etymology been metamorphosed into
+"Kartoffel".  In France the shape of the tubers suggested the name of
+earth-apple (pomme de terre), a name also adopted in Dutch (aard-appel),
+while dialectically in German a form "Grumbire" appears, which is a
+corruption of "Grund-birne", "ground pear".  (Kluge "Etymologisches
+Worterbuch der deutschen Sprache" (Strassburg), s.v. "Kartoffel".)  Here
+half the languages have adopted the original American word for an allied
+plant, while others have adopted a name originating in some more or less
+fanciful resemblance discovered in the tubers; the Germans alone in Western
+Europe, failing to see any meaning in their borrowed name, have modified it
+almost beyond recognition.  To this English supplies an exact parallel in
+"parsnep" which, though representing the Latin "pastinaca" through the Old
+French "pastenaque", was first assimilated in the last syllable to the
+"nep" of "turnep" ("pasneppe" in Elizabethan English), and later had an "r"
+introduced into the first syllable, apparently on the analogy of "parsley".
+
+The turkey on the other hand seems never to be found with its original
+American name.  In England, as the name implies, the turkey cock was
+regarded as having come from the land of the Turks.  The bird no doubt
+spread over Europe from the Italian seaports.  The mistake, therefore, was
+not unnatural, seeing that these towns conducted a great trade with the
+Levant, while the fact that America when first discovered was identified
+with India helped to increase the confusion.  Thus in French the "coq
+d'Inde" was abbreviated to "d'Inde" much as "turkey cock" was to "turkey";
+the next stage was to identify "dinde" as a feminine word and create a new
+"dindon" on the analogy of "chapon" as the masculine.  In Italian the name
+"gallo d'India" besides survives, while in German the name "Truthahn" seems
+to be derived onomatopoetically from the bird's cry, though a dialectic
+"Calecutischer Hahn" specifies erroneously an origin for the bird from the
+Indian Calicut.  In the Spanish "pavo", on the other hand, there is a
+curious confusion with the peacock.  Thus in these names for objects of
+common knowledge, the introduction of which into Europe can be dated with
+tolerable definiteness, we see evinced the methods by which in remoter ages
+objects were named.  The words were borrowed from the community whence came
+the new object, or the real or fancied resemblance to some known object
+gave the name, or again popular etymology might convert the unknown term
+into something that at least approached in sound a well-known word.
+
+"The Origin of Species" had not long been published when the parallelism of
+development in natural species and in languages struck investigators.  At
+the time, one of the foremost German philologists was August Schleicher,
+Professor at Jena.  He was himself keenly interested in the natural
+sciences, and amongst his colleagues was Ernst Haeckel, the protagonist in
+Germany of the Darwinian theory.  How the new ideas struck Schleicher may
+be seen from the following sentences by his colleague Haeckel.  "Speech is
+a physiological function of the human organism, and has been developed
+simultaneously with its organs, the larynx and tongue, and with the
+functions of the brain.  Hence it will be quite natural to find in the
+evolution and classification of languages the same features as in the
+evolution and classification of organic species.  The various groups of
+languages that are distinguished in philology as primitive, fundamental,
+parent, and daughter languages, dialects, etc., correspond entirely in
+their development to the different categories which we classify in zoology
+and botany as stems, classes, orders, families, genera, species and
+varieties.  The relation of these groups, partly coordinate and partly
+subordinate, in the general scheme is just the same in both cases; and the
+evolution follows the same lines in both."  (Haeckel, "The Evolution of
+Man", page 485, London, 1905.  This represents Schleicher's own words:  Was
+die Naturforscher als Gattung bezeichnen wurden, heisst bei den Glottikern
+Sprachstamm, auch Sprachsippe; naher verwandte Gattungen bezeichnen sie
+wohl auch als Sprachfamilien einer Sippe oder eines Sprachstammes...Die
+Arten einer Gattung nennen wir Sprachen eines Stammes; die Unterarten einer
+Art sind bei uns die Dialekte oder Mundarten einer Sprache; den Varietaten
+und Spielarten entsprechen die Untermundarten oder Nebenmundarten und
+endlich den einzelnen Individuen die Sprechweise der einzelnen die Sprachen
+redenden Menschen.  "Die Darwinische Theorie und die Sprachwissenschaft",
+Weimar, 1863, page 12 f.  Darwin makes a more cautious statement about the
+classification of languages in "The Origin of Species", page 578, (Popular
+Edition, 1900).)  These views were set forth in an open letter addressed to
+Haeckel in 1863 by Schleicher entitled, "The Darwinian theory and the
+science of language".  Unfortunately Schleicher's views went a good deal
+farther than is indicated in the extract given above.  He appended to the
+pamphlet a genealogical tree of the Indo-Germanic languages which, though
+to a large extent confirmed by later research, by the dichotomy of each
+branch into two other branches, led the unwary reader to suppose their
+phylogeny (to use Professor Haeckel's term) was more regular than our
+evidence warrants.
+
+Without qualification Schleicher declared languages to be "natural
+organisms which originated unconditioned by the human will, developed
+according to definite laws, grow old and die; they also are characterised
+by that series of phenomena which we designate by the term 'Life.' 
+Consequently Glottic, the science of language, is a natural science; its
+method is in general the same as that of the other natural sciences." 
+("Die Darwinische Theorie", page 6 f.)  In accordance with this view he
+declared (op. cit. page 23.) that the root in language might be compared
+with the simple cell in physiology, the linguistic simple cell or root
+being as yet not differentiated into special organs for the function of
+noun, verb, etc.
+
+In this probably all recent philologists admit that Schleicher went too
+far.  One of the most fertile theories in the modern science of language
+originated with him, and was further developed by his pupil, August Leskien
+("Die Declination im Slavisch-litanischen und Germanischen", Leipzig, 1876;
+Osthoff and Brugmann, "Morphologische Untersuchungen", I. (Introduction),
+1878.  The general principles of this school were formulated (1880) in a
+fuller form in H. Paul's "Prinzipien der Sprachgeschichte", Halle (3rd
+edition, 1898).  Paul and Wundt (in his "Volkerpsychologie") deal largely
+with the same matter, but begin their investigations from different points
+of view, Paul being a philologist with leanings to philosophy and Wundt a
+philosopher interested in language.), and by Leskien's colleagues and
+friends, Brugmann and Osthoff.  This was the principle that phonetic laws
+have no exceptions.  Under the influence of this generalisation much
+greater precision in etymology was insisted upon, and a new and remarkably
+active period in the study of language began.  Stated broadly in the
+fashion given above the principle is not true.  A more accurate statement
+would be that an original sound is represented in a given dialect at a
+given time and in a given environment only in one way; provided that the
+development of the original sound into its representation in the given
+dialect has not been influenced by the working of analogy.
+
+It is this proviso that is most important for the characterisation of the
+science of language.  As I have said elsewhere, it is at this point that
+this science parts company with the natural sciences.  "If the chemist
+compounds two pure simple elements, there can be but one result, and no
+power of the chemist can prevent it.  But the minds of men do act upon the
+sounds which they produce.  The result is that, when this happens, the
+phonetic law which would have acted in the case is stopped, and this
+particular form enters on the same course of development as other forms to
+which it does not belong."  (P. Giles, "Short Manual of Comparative
+Philology", 2nd edition, page 57, London, 1901.)
+
+Schleicher was wrong in defining a language to be an organism in the sense
+in which a living being is an organism.  Regarded physiologically, language
+is a function or potentiality of certain human organs; regarded from the
+point of view of the community it is of the nature of an institution. 
+(This view of language is worked out at some length by Prof. W.D. Whitney
+in an article in the "Contemporary Review" for 1875, page 713 ff.  This
+article forms part of a controversy with Max Muller, which is partly
+concerned with Darwin's views on language.  He criticises Schleicher's
+views severely in his "Oriental and Linguistic Studies", page 298 ff., New
+York, 1873.  In this volume will be found criticisms of various other views
+mentioned in this essay.)  More than most influences it conduces to the
+binding together of the elements that form a state.  That geographical or
+other causes may effectively counteract the influence of identity of
+language is obvious.  One need only read the history of ancient Greece, or
+observe the existing political separation of Germany and Austria, of Great
+Britain and the United States of America.  But however analogous to an
+organism, language is not an organism.  In a less degree Schleicher, by
+defining languages as such, committed the same mistake which Bluntschli
+made regarding the State, and which led him to declare that the State is by
+nature masculine and the Church feminine.  (Bluntschli, "Theory of the
+State", page 24, Second English Edition, Oxford, 1892.)  The views of
+Schleicher were to some extent injurious to the proper methods of
+linguistic study.  But this misfortune was much more than fully compensated
+by the inspiration which his ideas, collected and modified by his
+disciples, had upon the science.  In spite of the difference which the
+psychological element represented by analogy makes between the science of
+language and the natural sciences, we are entitled to say of it as
+Schleicher said of Darwin's theory of the origin of species, "it depends
+upon observation, and is essentially an attempt at a history of
+development."
+
+Other questions there are in connection with language and evolution which
+require investigation--the survival of one amongst several competing words
+(e.g. why German keeps only as a high poetic word "ross", which is
+identical in origin with the English work-a-day "horse", and replaces it by
+"pferd", whose congener the English "palfrey" is almost confined to poetry
+and romance), the persistence of evolution till it becomes revolution in
+languages like English or Persian which have practically ceased to be
+inflectional languages, and many other problems.  Into these Darwin did not
+enter, and they require a fuller investigation than is possible within the
+limits of the present paper.
+
+
+XXVII.  DARWINISM AND HISTORY.
+
+By J.B. BURY, Litt.D., LL.D.
+Regius Professor of Modern History in the University of Cambridge.
+
+1.  Evolution, and the principles associated with the Darwinian theory,
+could not fail to exert a considerable influence on the studies connected
+with the history of civilised man.  The speculations which are known as
+"philosophy of history," as well as the sciences of anthropology,
+ethnography, and sociology (sciences which though they stand on their own
+feet are for the historian auxiliary), have been deeply affected by these
+principles.  Historiographers, indeed, have with few exceptions made little
+attempt to apply them; but the growth of historical study in the nineteenth
+century has been determined and characterised by the same general principle
+which has underlain the simultaneous developments of the study of nature,
+namely the GENETIC idea.  The "historical" conception of nature, which has
+produced the history of the solar system, the story of the earth, the
+genealogies of telluric organisms, and has revolutionised natural science,
+belongs to the same order of thought as the conception of human history as
+a continuous, genetic, causal process--a conception which has
+revolutionised historical research and made it scientific.  Before
+proceeding to consider the application of evolutional principles, it will
+be pertinent to notice the rise of this new view.
+
+2.  With the Greeks and Romans history had been either a descriptive record
+or had been written in practical interests.  The most eminent of the
+ancient historians were pragmatical; that is, they regarded history as an
+instructress in statesmanship, or in the art of war, or in morals.  Their
+records reached back such a short way, their experience was so brief, that
+they never attained to the conception of continuous process, or realised
+the significance of time; and they never viewed the history of human
+societies as a phenomenon to be investigated for its own sake.  In the
+middle ages there was still less chance of the emergence of the ideas of
+progress and development.  Such notions were excluded by the fundamental
+doctrines of the dominant religion which bounded and bound men's minds.  As
+the course of history was held to be determined from hour to hour by the
+arbitrary will of an extra-cosmic person, there could be no self-contained
+causal development, only a dispensation imposed from without.  And as it
+was believed that the world was within no great distance from the end of
+this dispensation, there was no motive to take much interest in
+understanding the temporal, which was to be only temporary.
+
+The intellectual movements of the fifteenth and sixteenth centuries
+prepared the way for a new conception, but it did not emerge immediately.
+The historians of the Renaissance period simply reverted to the ancient
+pragmatical view.  For Machiavelli, exactly as for Thucydides and Polybius,
+the use of studying history was instruction in the art of politics.  The
+Renaissance itself was the appearance of a new culture, different from
+anything that had gone before; but at the time men were not conscious of
+this; they saw clearly that the traditions of classical antiquity had been
+lost for a long period, and they were seeking to revive them, but otherwise
+they did not perceive that the world had moved, and that their own spirit,
+culture, and conditions were entirely unlike those of the thirteenth
+century.  It was hardly till the seventeenth century that the presence of a
+new age, as different from the middle ages as from the ages of Greece and
+Rome, was fully realised.  It was then that the triple division of ancient,
+medieval, and modern was first applied to the history of western
+civilisation.  Whatever objections may be urged against this division,
+which has now become almost a category of thought, it marks a most
+significant advance in man's view of his own past.  He has become conscious
+of the immense changes in civilisation which have come about slowly in the
+course of time, and history confronts him with a new aspect.  He has to
+explain how those changes have been produced, how the transformations were
+effected.  The appearance of this problem was almost simultaneous with the
+rise of rationalism, and the great historians and thinkers of the
+eighteenth century, such as Montesquieu, Voltaire, Gibbon, attempted to
+explain the movement of civilisation by purely natural causes.  These
+brilliant writers prepared the way for the genetic history of the following
+century.  But in the spirit of the Aufklarung, that eighteenth-century
+Enlightenment to which they belonged, they were concerned to judge all
+phenomena before the tribunal of reason; and the apotheosis of "reason"
+tended to foster a certain superior a priori attitude, which was not
+favourable to objective treatment and was incompatible with a "historical
+sense."  Moreover the traditions of pragmatical historiography had by no
+means disappeared.
+
+3.  In the first quarter of the nineteenth century the meaning of genetic
+history was fully realised.  "Genetic" perhaps is as good a word as can be
+found for the conception which in this century was applied to so many
+branches of knowledge in the spheres both of nature and of mind.  It does
+not commit us to the doctrine proper of evolution, nor yet to any
+teleological hypothesis such as is implied in "progress."  For history it
+meant that the present condition of the human race is simply and strictly
+the result of a causal series (or set of causal series)--a continuous
+succession of changes, where each state arises causally out of the
+preceding; and that the business of historians is to trace this genetic
+process, to explain each change, and ultimately to grasp the complete
+development of the life of humanity.  Three influential writers, who
+appeared at this stage and helped to initiate a new period of research, may
+specially be mentioned.  Ranke in 1824 definitely repudiated the
+pragmatical view which ascribes to history the duties of an instructress,
+and with no less decision renounced the function, assumed by the historians
+of the Aufklarung, to judge the past; it was his business, he said, merely
+to show how things really happened.  Niebuhr was already working in the
+same spirit and did more than any other writer to establish the principle
+that historical transactions must be related to the ideas and conditions of
+their age.  Savigny about the same time founded the "historical school" of
+law.  He sought to show that law was not the creation of an enlightened
+will, but grew out of custom and was developed by a series of adaptations
+and rejections, thus applying the conception of evolution.  He helped to
+diffuse the notion that all the institutions of a society or a notion are
+as closely interconnected as the parts of a living organism.
+
+4.  The conception of the history of man as a causal development meant the
+elevation of historical inquiry to the dignity of a science.  Just as the
+study of bees cannot become scientific so long as the student's interest in
+them is only to procure honey or to derive moral lessons from the labours
+of "the little busy bee," so the history of human societies cannot become
+the object of pure scientific investigation so long as man estimates its
+value in pragmatical scales.  Nor can it become a science until it is
+conceived as lying entirely within a sphere in which the law of cause and
+effect has unreserved and unrestricted dominion.  On the other hand, once
+history is envisaged as a causal process, which contains within itself the
+explanation of the development of man from his primitive state to the point
+which he has reached, such a process necessarily becomes the object of
+scientific investigation and the interest in it is scientific curiosity.
+
+At the same time, the instruments were sharpened and refined.  Here Wolf, a
+philologist with historical instinct, was a pioneer.  His "Prolegomena" to
+Homer (1795) announced new modes of attack.  Historical investigation was
+soon transformed by the elaboration of new methods.
+
+5.  "Progress" involves a judgment of value, which is not involved in the
+conception of history as a genetic process.  It is also an idea distinct
+from that of evolution.  Nevertheless it is closely related to the ideas
+which revolutionised history at the beginning of the last century; it swam
+into men's ken simultaneously; and it helped effectively to establish the
+notion of history as a continuous process and to emphasise the significance
+of time.  Passing over earlier anticipations, I may point to a "Discours"
+of Turgot (1750), where history is presented as a process in which "the
+total mass of the human race" "marches continually though sometimes slowly
+to an ever increasing perfection."  That is a clear statement of the
+conception which Turgot's friend Condorcet elaborated in the famous work,
+published in 1795, "Esquisse d'un tableau historique des progres de
+l'esprit humain".  This work first treated with explicit fulness the idea
+to which a leading role was to fall in the ideology of the nineteenth
+century.  Condorcet's book reflects the triumphs of the Tiers etat, whose
+growing importance had also inspired Turgot; it was the political changes
+in the eighteenth century which led to the doctrine, emphatically
+formulated by Condorcet, that the masses are the most important element in
+the historical process.  I dwell on this because, though Condorcet had no
+idea of evolution, the pre-dominant importance of the masses was the
+assumption which made it possible to apply evolutional principles to
+history.  And it enabled Condorcet himself to maintain that the history of
+civilisation, a progress still far from being complete, was a development
+conditioned by general laws.
+
+6.  The assimilation of society to an organism, which was a governing
+notion in the school of Savigny, and the conception of progress, combined
+to produce the idea of an organic development, in which the historian has
+to determine the central principle or leading character.  This is
+illustrated by the apotheosis of democracy in Tocqueville's "Democratie en
+Amerique", where the theory is maintained that "the gradual and progressive
+development of equality is at once the past and the future of the history
+of men."  The same two principles are combined in the doctrine of Spencer
+(who held that society is an organism, though he also contemplated its
+being what he calls a "super-organic aggregate") (A society presents
+suggestive analogies with an organism, but it certainly is not an organism,
+and sociologists who draw inferences from the assumption of its organic
+nature must fall into error.  A vital organism and a society are radically
+distinguished by the fact that the individual components of the former,
+namely the cells, are morphologically as well as functionally
+differentiated, whereas the individuals which compose a society are
+morphologically homogeneous and only functionally differentiated.  The
+resemblances and the differences are worked out in E. de Majewski's
+striking book "La Science de la Civilisation", Paris, 1908.), that social
+evolution is a progressive change from militarism to industrialism.
+
+7. the idea of development assumed another form in the speculations of
+German idealism.  Hegel conceived the successive periods of history as
+corresponding to the ascending phases or ideas in the self-evolution of his
+Absolute Being.  His "Lectures on the Philosophy of History" were published
+in 1837 after his death.  His philosophy had a considerable effect, direct
+and indirect, on the treatment of history by historians, and although he
+was superficial and unscientific himself in dealing with historical
+phenomena, he contributed much towards making the idea of historical
+development familiar.  Ranke was influenced, if not by Hegel himself, at
+least by the Idealistic philosophies of which Hegel's was the greatest.  He
+was inclined to conceive the stages in the process of history as marked by
+incarnations, as it were, of ideas, and sometimes speaks as if the ideas
+were independent forces, with hands and feet.  But while Hegel determined
+his ideas by a priori logic, Ranke obtained his by induction--by a strict
+investigation of the phenomena; so that he was scientific in his method and
+work, and was influenced by Hegelian prepossessions only in the kind of
+significance which he was disposed to ascribe to his results.  It is to be
+noted that the theory of Hegel implied a judgment of value; the movement
+was a progress towards perfection.
+
+8.  In France, Comte approached the subject from a different side, and
+exercised, outside Germany, a far wider influence than Hegel.  The 4th
+volume of his "Cours de philosophie positive", which appeared in 1839,
+created sociology and treated history as a part of this new science, namely
+as "social dynamics."  Comte sought the key for unfolding historical
+development, in what he called the social-psychological point of view, and
+he worked out the two ideas which had been enunciated by Condorcet:  that
+the historian's attention should be directed not, as hitherto, principally
+to eminent individuals, but to the collective behaviour of the masses, as
+being the most important element in the process; and that, as in nature, so
+in history, there are general laws, necessary and constant, which condition
+the development.  The two points are intimately connected, for it is only
+when the masses are moved into the foreground that regularity, uniformity,
+and law can be conceived as applicable.  To determine the social-
+psychological laws which have controlled the development is, according to
+Comte, the task of sociologists and historians.
+
+9.  The hypothesis of general laws operative in history was carried further
+in a book which appeared in England twenty years later and exercised an
+influence in Europe far beyond its intrinsic merit, Buckle's "History of
+Civilisation in England" (1857-61).  Buckle owed much to Comte, and
+followed him, or rather outdid him, in regarding intellect as the most
+important factor conditioning the upward development of man, so that
+progress, according to him, consisted in the victory of the intellectual
+over the moral laws.
+
+10.  The tendency of Comte and Buckle to assimilate history to the sciences
+of nature by reducing it to general "laws," derived stimulus and
+plausibility from the vista offered by the study of statistics, in which
+the Belgian Quetelet, whose book "Sur l'homme" appeared in 1835, discerned
+endless possibilities.  The astonishing uniformities which statistical
+inquiry disclosed led to the belief that it was only a question of
+collecting a sufficient amount of statistical material, to enable us to
+predict how a given social group will act in a particular case.  Bourdeau,
+a disciple of this school, looks forward to the time when historical
+science will become entirely quantitative.  The actions of prominent
+individuals, which are generally considered to have altered or determined
+the course of things, are obviously not amenable to statistical computation
+or explicable by general laws.  Thinkers like Buckle sought to minimise
+their importance or explain them away.
+
+11.  These indications may suffice to show that the new efforts to
+interpret history which marked the first half of the nineteenth century
+were governed by conceptions closely related to those which were current in
+the field of natural science and which resulted in the doctrine of
+evolution.  The genetic principle, progressive development, general laws,
+the significance of time, the conception of society as an organic
+aggregate, the metaphysical theory of history as the self-evolution of
+spirit,--all these ideas show that historical inquiry had been advancing
+independently on somewhat parallel lines to the sciences of nature.  It was
+necessary to bring this out in order to appreciate the influence of
+Darwinism.
+
+12.  In the course of the dozen years which elapsed between the appearances
+of "The Origin of Species" (observe that the first volume of Buckle's work
+was published just two years before) and of "The Descent of Man" (1871),
+the hypothesis of Lamarck that man is the co-descendant with other species
+of some lower extinct form was admitted to have been raised to the rank of
+an established fact by most thinkers whose brains were not working under
+the constraint of theological authority.
+
+One important effect of the discovery of this fact (I am not speaking now
+of the Darwinian explanation) was to assign to history a definite place in
+the coordinated whole of knowledge, and relate it more closely to other
+sciences.  It had indeed a defined logical place in systems such as Hegel's
+and Comte's; but Darwinism certified its standing convincingly and without
+more ado.  The prevailing doctrine that man was created ex abrupto had
+placed history in an isolated position, disconnected with the sciences of
+nature.  Anthropology, which deals with the animal anthropos, now comes
+into line with zoology, and brings it into relation with history.  (It is
+to be observed that history is (not only different in scope but) not
+coextensive with anthropology IN TIME.  For it deals only with the
+development of man in societies, whereas anthropology includes in its
+definition the proto-anthropic period when anthropos was still non-social,
+whether he lived in herds like the chimpanzee, or alone like the male
+ourang-outang.  (It has been well shown by Majewski that congregations--
+herds, flocks, packs, etc.--of animals are not SOCIETIES; the
+characteristic of a society is differentiation of function.  Bee hives, ant
+hills, may be called quasi-societies; but in their case the classes which
+perform distinct functions are morphologically different.)  Man's condition
+at the present day is the result of a series of transformations, going back
+to the most primitive phase of society, which is the ideal (unattainable)
+beginning of history.  But that beginning had emerged without any breach of
+continuity from a development which carries us back to a quadrimane
+ancestor, still further back (according to Darwin's conjecture) to a marine
+animal of the ascidian type, and then through remoter periods to the lowest
+form of organism.  It is essential in this theory that though links have
+been lost there was no break in the gradual development; and this
+conception of a continuous progress in the evolution of life, resulting in
+the appearance of uncivilised Anthropos, helped to reinforce, and increase
+a belief in, the conception of the history of civilised Anthropos as itself
+also a continuous progressive development.
+
+13.  Thus the diffusion of the Darwinian theory of the origin of man, by
+emphasising the idea of continuity and breaking down the barriers between
+the human and animal kingdoms, has had an important effect in establishing
+the position of history among the sciences which deal with telluric
+development.  The perspective of history is merged in a larger perspective
+of development.  As one of the objects of biology is to find the exact
+steps in the genealogy of man from the lowest organic form, so the scope of
+history is to determine the stages in the unique causal series from the
+most rudimentary to the present state of human civilisation.
+
+It is to be observed that the interest in historical research implied by
+this conception need not be that of Comte.  In the Positive Philosophy
+history is part of sociology; the interest in it is to discover the
+sociological laws.  In the view of which I have just spoken, history is
+permitted to be an end in itself; the reconstruction of the genetic process
+is an independent interest.  For the purpose of the reconstruction,
+sociology, as well as physical geography, biology, psychology, is
+necessary; the sociologist and the historian play into each other's hands;
+but the object of the former is to establish generalisations; the aim of
+the latter is to trace in detail a singular causal sequence.
+
+14.  The success of the evolutional theory helped to discredit the
+assumption or at least the invocation of transcendent causes. 
+Philosophically of course it is compatible with theism, but historians have
+for the most part desisted from invoking the naive conception of a "god in
+history" to explain historical movements.  A historian may be a theist;
+but, so far as his work is concerned, this particular belief is otiose. 
+Otherwise indeed (as was remarked above) history could not be a science;
+for with a deus ex machina who can be brought on the stage to solve
+difficulties scientific treatment is a farce.  The transcendent element had
+appeared in a more subtle form through the influence of German philosophy. 
+I noticed how Ranke is prone to refer to ideas as if they were transcendent
+existences manifesting themselves in the successive movements of history. 
+It is intelligible to speak of certain ideas as controlling, in a given
+period,--for instance, the idea of nationality; but from the scientific
+point of view, such ideas have no existence outside the minds of
+individuals and are purely psychical forces; and a historical "idea," if it
+does not exist in this form, is merely a way of expressing a synthesis of
+the historian himself.
+
+15.  From the more general influence of Darwinism on the place of history
+in the system of human knowledge, we may turn to the influence of the
+principles and methods by which Darwin explained development.  It had been
+recognised even by ancient writers (such as Aristotle and Polybius) that
+physical circumstances (geography, climate) were factors conditioning the
+character and history of a race or society.  In the sixteenth century Bodin
+emphasised these factors, and many subsequent writers took them into
+account.  The investigations of Darwin, which brought them into the
+foreground, naturally promoted attempts to discover in them the chief key
+to the growth of civilisation.  Comte had expressly denounced the notion
+that the biological methods of Lamarck could be applied to social man. 
+Buckle had taken account of natural influences, but had relegated them to a
+secondary plane, compared with psychological factors.  But the Darwinian
+theory made it tempting to explain the development of civilisation in terms
+of "adaptation to environment," "struggle for existence," "natural
+selection," "survival of the fittest," etc. (Recently O. Seeck has applied
+these principles to the decline of Graeco-Roman civilisation in his
+"Untergang der antiken Welt", 2 volumes, Berlin, 1895, 1901.)
+
+The operation of these principles cannot be denied.  Man is still an
+animal, subject to zoological as well as mechanical laws.  The dark
+influence of heredity continues to be effective; and psychical development
+had begun in lower organic forms,--perhaps with life itself.  The organic
+and the social struggles for existence are manifestations of the same
+principle.  Environment and climatic influence must be called in to explain
+not only the differentiation of the great racial sections of humanity, but
+also the varieties within these sub-species and, it may be, the
+assimilation of distinct varieties.  Ritter's "Anthropogeography" has
+opened a useful line of research.  But on the other hand, it is urged that,
+in explaining the course of history, these principles do not take us very
+far, and that it is chiefly for the primitive ultra-prehistoric period that
+they can account for human development.  It may be said that, so far as
+concerns the actions and movements of men which are the subject of recorded
+history, physical environment has ceased to act mechanically, and in order
+to affect their actions must affect their wills first; and that this
+psychical character of the causal relations substantially alters the
+problem.  The development of human societies, it may be argued, derives a
+completely new character from the dominance of the conscious psychical
+element, creating as it does new conditions (inventions, social
+institutions, etc.) which limit and counteract the operation of natural
+selection, and control and modify the influence of physical environment. 
+Most thinkers agree now that the chief clews to the growth of civilisation
+must be sought in the psychological sphere.  Imitation, for instance, is a
+principle which is probably more significant for the explanation of human
+development than natural selection.  Darwin himself was conscious that his
+principles had only a very restricted application in this sphere, as is
+evident from his cautious and tentative remarks in the 5th chapter of his
+"Descent of Man".  He applied natural selection to the growth of the
+intellectual faculties and of the fundamental social instincts, and also to
+the differentiation of the great races or "sub-species" (Caucasian,
+African, etc.) which differ in anthropological character.  (Darwinian
+formulae may be suggestive by way of analogy.  For instance, it is
+characteristic of social advance that a multitude of inventions, schemes
+and plans are framed which are never carried out, similar to, or designed
+for the same end as, an invention or plan which is actually adopted because
+it has chanced to suit better the particular conditions of the hour (just
+as the works accomplished by an individual statesman, artist or savant are
+usually only a residue of the numerous projects conceived by his brain). 
+This process in which so much abortive production occurs is analogous to
+elimination by natural selection.)
+
+16.  But if it is admitted that the governing factors which concern the
+student of social development are of the psychical order, the preliminary
+success of natural science in explaining organic evolution by general
+principles encouraged sociologists to hope that social evolution could be
+explained on general principles also.  The idea of Condorcet, Buckle, and
+others, that history could be assimilated to the natural sciences was
+powerfully reinforced, and the notion that the actual historical process,
+and every social movement involved in it, can be accounted for by
+sociological generalisations, so-called "laws," is still entertained by
+many, in one form or another.  Dissentients from this view do not deny that
+the generalisations at which the sociologist arrives by the comparative
+method, by the analysis of social factors, and by psychological deduction
+may be an aid to the historian; but they deny that such uniformities are
+laws or contain an explanation of the phenomena.  They can point to the
+element of chance coincidence.  This element must have played a part in the
+events of organic evolution, but it has probably in a larger measure helped
+to determine events in social evolution.  The collision of two unconnected
+sequences may be fraught with great results.  The sudden death of a leader
+or a marriage without issue, to take simple cases, has again and again led
+to permanent political consequences.  More emphasis is laid on the decisive
+actions of individuals, which cannot be reduced under generalisations and
+which deflect the course of events.  If the significance of the individual
+will had been exaggerated to the neglect of the collective activity of the
+social aggregate before Condorcet, his doctrine tended to eliminate as
+unimportant the roles of prominent men, and by means of this elimination it
+was possible to found sociology.  But it may be urged that it is patent on
+the face of history that its course has constantly been shaped and modified
+by the wills of individuals (We can ignore here the metaphysical question
+of freewill and determinism.  For the character of the individual's brain
+depends in any case on ante-natal accidents and coincidences, and so it may
+be said that the role of individuals ultimately depends on chance,--the
+accidental coincidence of independent sequences.), which are by no means
+always the expression of the collective will; and that the appearance of
+such personalities at the given moments is not a necessary outcome of the
+conditions and cannot be deduced.  Nor is there any proof that, if such and
+such an individual had not been born, some one else would have arisen to do
+what he did.  In some cases there is no reason to think that what happened
+need ever have come to pass.  In other cases, it seems evident that the
+actual change was inevitable, but in default of the man who initiated and
+guided it, it might have been postponed, and, postponed or not, might have
+borne a different cachet.  I may illustrate by an instance which has just
+come under my notice.  Modern painting was founded by Giotto, and the
+Italian expedition of Charles VIII, near the close of the sixteenth
+century, introduced into France the fashion of imitating Italian painters.
+But for Giotto and Charles VIII, French painting might have been very
+different.  It may be said that "if Giotto had not appeared, some other
+great initiator would have played a role analogous to his, and that without
+Charles VIII there would have been the commerce with Italy, which in the
+long run would have sufficed to place France in relation with Italian
+artists.  But the equivalent of Giotto might have been deferred for a
+century and probably would have been different; and commercial relations
+would have required ages to produce the rayonnement imitatif of Italian art
+in France, which the expedition of the royal adventurer provoked in a few
+years."  (I have taken this example from G. Tarde's "La logique sociale" 2
+(page 403), Paris, 1904, where it is used for quite a different purpose.) 
+Instances furnished by political history are simply endless.  Can we
+conjecture how events would have moved if the son of Philip of Macedon had
+been an incompetent?  The aggressive action of Prussia which astonished
+Europe in 1740 determined the subsequent history of Germany; but that
+action was anything but inevitable; it depended entirely on the personality
+of Frederick the Great.
+
+Hence it may be argued that the action of individual wills is a determining
+and disturbing factor, too significant and effective to allow history to be
+grasped by sociological formulae.  The types and general forms of
+development which the sociologist attempts to disengage can only assist the
+historian in understanding the actual course of events.  It is in the
+special domains of economic history and Culturgeschichte which have come to
+the front in modern times that generalisation is most fruitful, but even in
+these it may be contended that it furnishes only partial explanations.
+
+17.  The truth is that Darwinism itself offers the best illustration of the
+insufficiency of general laws to account for historical development.  The
+part played by coincidence, and the part played by individuals--limited by,
+and related to, general social conditions--render it impossible to deduce
+the course of the past history of man or to predict the future.  But it is
+just the same with organic development.  Darwin (or any other zoologist)
+could not deduce the actual course of evolution from general principles. 
+Given an organism and its environment, he could not show that it must
+evolve into a more complex organism of a definite pre-determined type;
+knowing what it has evolved into, he could attempt to discover and assign
+the determining causes.  General principles do not account for a particular
+sequence; they embody necessary conditions; but there is a chapter of
+accidents too.  It is the same in the case of history.
+
+18.  Among the evolutional attempts to subsume the course of history under
+general syntheses, perhaps the most important is that of Lamprecht, whose
+"kulturhistorische Methode," which he has deduced from and applied to
+German history, exhibits the (indirect) influence of the Comtist school. 
+It is based upon psychology, which, in his view, holds among the sciences
+of mind (Geisteswissenschaften) the same place (that of a
+Grundwissenschaft) which mechanics holds among the sciences of nature. 
+History, by the same comparison, corresponds to biology, and, according to
+him, it can only become scientific if it is reduced to general concepts
+(Begriffe).  Historical movements and events are of a psychical character,
+and Lamprecht conceives a given phase of civilisation as "a collective
+psychical condition (seelischer Gesamtzustand)" controlling the period, "a
+diapason which penetrates all psychical phenomena and thereby all
+historical events of the time."  ("Die kulturhistorische Methode", Berlin,
+1900, page 26.)  He has worked out a series of such phases, "ages of
+changing psychical diapason," in his "Deutsche Geschichte" with the aim of
+showing that all the feelings and actions of each age can be explained by
+the diapason; and has attempted to prove that these diapasons are exhibited
+in other social developments, and are consequently not singular but
+typical.  He maintains further that these ages succeed each other in a
+definite order; the principle being that the collective psychical
+development begins with the homogeneity of all the individual members of a
+society and, through heightened psychical activity, advances in the form of
+a continually increasing differentiation of the individuals (this is akin
+to the Spencerian formula).  This process, evolving psychical freedom from
+psychical constraint, exhibits a series of psychical phenomena which define
+successive periods of civilisation.  The process depends on two simple
+principles, that no idea can disappear without leaving behind it an effect
+or influence, and that all psychical life, whether in a person or a
+society, means change, the acquisition of new mental contents.  It follows
+that the new have to come to terms with the old, and this leads to a
+synthesis which determines the character of a new age.  Hence the ages of
+civilisation are defined as the "highest concepts for subsuming without
+exception all psychical phenomena of the development of human societies,
+that is, of all historical events."  (Ibid. pages 28, 29.)  Lamprecht
+deduces the idea of a special historical science, which might be called
+"historical ethnology," dealing with the ages of civilisation, and bearing
+the same relation to (descriptive or narrative) history as ethnology to
+ethnography.  Such a science obviously corresponds to Comte's social
+dynamics, and the comparative method, on which Comte laid so much emphasis,
+is the principal instrument of Lamprecht.
+
+19.  I have dwelt on the fundamental ideas of Lamprecht, because they are
+not yet widely known in England, and because his system is the ablest
+product of the sociological school of historians.  It carries the more
+weight as its author himself is a historical specialist, and his historical
+syntheses deserve the most careful consideration.  But there is much in the
+process of development which on such assumptions is not explained,
+especially the initiative of individuals.  Historical development does not
+proceed in a right line, without the choice of diverging.  Again and again,
+several roads are open to it, of which it chooses one--why?  On Lamprecht's
+method, we may be able to assign the conditions which limit the psychical
+activity of men at a particular stage of evolution, but within those limits
+the individual has so many options, such a wide room for moving, that the
+definition of those conditions, the "psychical diapasons," is only part of
+the explanation of the particular development.  The heel of Achilles in all
+historical speculations of this class has been the role of the individual.
+
+The increasing prominence of economic history has tended to encourage the
+view that history can be explained in terms of general concepts or types. 
+Marx and his school based their theory of human development on the
+conditions of production, by which, according to them, all social movements
+and historical changes are entirely controlled.  The leading part which
+economic factors play in Lamprecht's system is significant, illustrating
+the fact that economic changes admit most readily this kind of treatment,
+because they have been less subject to direction or interference by
+individual pioneers.
+
+Perhaps it may be thought that the conception of SOCIAL ENVIRONMENT
+(essentially psychical), on which Lamprecht's "psychical diapasons" depend,
+is the most valuable and fertile conception that the historian owes to the
+suggestion of the science of biology--the conception of all particular
+historical actions and movements as (1) related to and conditioned by the
+social environment, and (2) gradually bringing about a transformation of
+that environment.  But no given transformation can be proved to be
+necessary (pre-determined).  And types of development do not represent
+laws; their meaning and value lie in the help they may give to the
+historian, in investigating a certain period of civilisation, to enable him
+to discover the interrelations among the diverse features which it
+presents.  They are, as some one has said, an instrument of heuretic
+method.
+
+20.  The men engaged in special historical researches--which have been
+pursued unremittingly for a century past, according to scientific methods
+of investigating evidence (initiated by Wolf, Niebuhr, Ranke)--have for the
+most part worked on the assumptions of genetic history or at least followed
+in the footsteps of those who fully grasped the genetic point of view.  But
+their aim has been to collect and sift evidence, and determine particular
+facts; comparatively few have given serious thought to the lines of
+research and the speculations which have been considered in this paper. 
+They have been reasonably shy of compromising their work by applying
+theories which are still much debated and immature.  But historiography
+cannot permanently evade the questions raised by these theories.  One may
+venture to say that no historical change or transformation will be fully
+understood until it is explained how social environment acted on the
+individual components of the society (both immediately and by heredity),
+and how the individuals reacted upon their environment.  The problem is
+psychical, but it is analogous to the main problem of the biologist.
+
+
+XXVIII.  THE GENESIS OF DOUBLE STARS.
+
+By SIR GEORGE DARWIN, K.C.B., F.R.S.
+Plumian Professor of Astronomy and Experimental Philosophy in the
+University of Cambridge.
+
+In ordinary speech a system of any sort is said to be stable when it cannot
+be upset easily, but the meaning attached to the word is usually somewhat
+vague.  It is hardly surprising that this should be the case, when it is
+only within the last thirty years, and principally through the
+investigations of M. Poincare, that the conception of stability has, even
+for physicists, assumed a definiteness and clearness in which it was
+previously lacking.  The laws which govern stability hold good in regions
+of the greatest diversity; they apply to the motion of planets round the
+sun, to the internal arrangement of those minute corpuscles of which each
+chemical atom is constructed, and to the forms of celestial bodies.  In the
+present essay I shall attempt to consider the laws of stability as relating
+to the last case, and shall discuss the succession of shapes which may be
+assumed by celestial bodies in the course of their evolution.  I believe
+further that homologous conceptions are applicable in the consideration of
+the transmutations of the various forms of animal and of vegetable life and
+in other regions of thought.  Even if some of my readers should think that
+what I shall say on this head is fanciful, yet at least the exposition will
+serve to illustrate the meaning to be attached to the laws of stability in
+the physical universe.
+
+I propose, therefore, to begin this essay by a sketch of the principles of
+stability as they are now formulated by physicists.
+
+I.
+
+If a slight impulse be imparted to a system in equilibrium one of two
+consequences must ensue; either small oscillations of the system will be
+started, or the disturbance will increase without limit and the arrangement
+of the system will be completely changed.  Thus a stick may be in
+equilibrium either when it hangs from a peg or when it is balanced on its
+point.  If in the first case the stick is touched it will swing to and fro,
+but in the second case it will topple over.  The first position is a stable
+one, the second is unstable.  But this case is too simple to illustrate all
+that is implied by stability, and we must consider cases of stable and of
+unstable motion.  Imagine a satellite and its planet, and consider each of
+them to be of indefinitely small size, in fact particles; then the
+satellite revolves round its planet in an ellipse.  A small disturbance
+imparted to the satellite will only change the ellipse to a small amount,
+and so the motion is said to be stable.  If, on the other hand, the
+disturbance were to make the satellite depart from its initial elliptic
+orbit in ever widening circuits, the motion would be unstable.  This case
+affords an example of stable motion, but I have adduced it principally with
+the object of illustrating another point not immediately connected with
+stability, but important to a proper comprehension of the theory of
+stability.
+
+The motion of a satellite about its planet is one of revolution or
+rotation.  When the satellite moves in an ellipse of any given degree of
+eccentricity, there is a certain amount of rotation in the system,
+technically called rotational momentum, and it is always the same at every
+part of the orbit.  (Moment of momentum or rotational momentum is measured
+by the momentum of the satellite multiplied by the perpendicular from the
+planet on to the direction of the path of the satellite at any instant.)
+
+Now if we consider all the possible elliptic orbits of a satellite about
+its planet which have the same amount of "rotational momentum," we find
+that the major axis of the ellipse described will be different according to
+the amount of flattening (or the eccentricity) of the ellipse described.  A
+figure titled "A 'family' of elliptic orbits with constant rotational
+momentum" (Fig. 1) illustrates for a given planet and satellite all such
+orbits with constant rotational momentum, and with all the major axes in
+the same direction.  It will be observed that there is a continuous
+transformation from one orbit to the next, and that the whole forms a
+consecutive group, called by mathematicians "a family" of orbits.  In this
+case the rotational momentum is constant and the position of any orbit in
+the family is determined by the length of the major axis of the ellipse;
+the classification is according to the major axis, but it might have been
+made according to anything else which would cause the orbit to be exactly
+determinate.
+
+I shall come later to the classification of all possible forms of ideal
+liquid stars, which have the same amount of rotational momentum, and the
+classification will then be made according to their densities, but the idea
+of orderly arrangement in a "family" is just the same.
+
+We thus arrive at the conception of a definite type of motion, with a
+constant amount of rotational momentum, and a classification of all members
+of the family, formed by all possible motions of that type, according to
+the value of some measurable quantity (this will hereafter be density)
+which determines the motion exactly.  In the particular case of the
+elliptic motion used for illustration the motion was stable, but other
+cases of motion might be adduced in which the motion would be unstable, and
+it would be found that classification in a family and specification by some
+measurable quantity would be equally applicable.
+
+A complex mechanical system may be capable of motion in several distinct
+modes or types, and the motions corresponding to each such type may be
+arranged as before in families.  For the sake of simplicity I will suppose
+that only two types are possible, so that there will only be two families;
+and the rotational momentum is to be constant.  The two types of motion
+will have certain features in common which we denote in a sort of shorthand
+by the letter A.  Similarly the two types may be described as A + a and A +
+b, so that a and b denote the specific differences which discriminate the
+families from one another.  Now following in imagination the family of the
+type A + a, let us begin with the case where the specific difference a is
+well marked.  As we cast our eyes along the series forming the family, we
+find the difference a becoming less conspicuous.  It gradually dwindles
+until it disappears; beyond this point it either becomes reversed, or else
+the type has ceased to be a possible one.  In our shorthand we have started
+with A + a, and have watched the characteristic a dwindling to zero.  When
+it vanishes we have reached a type which may be specified as A; beyond this
+point the type would be A - a or would be impossible.
+
+Following the A + b type in the same way, b is at first well marked, it
+dwindles to zero, and finally may become negative.  Hence in shorthand this
+second family may be described as A + b,...A,...A - b.
+
+In each family there is one single member which is indistinguishable from a
+member of the other family; it is called by Poincare a form of bifurcation. 
+It is this conception of a form of bifurcation which forms the important
+consideration in problems dealing with the forms of liquid or gaseous
+bodies in rotation.
+
+But to return to the general question,--thus far the stability of these
+families has not been considered, and it is the stability which renders
+this way of looking at the matter so valuable.  It may be proved that if
+before the point of bifurcation the type A + a was stable, then A + b must
+have been unstable.  Further as a and b each diminish A + a becomes less
+pronouncedly stable, and A + b less unstable.  On reaching the point of
+bifurcation A + a has just ceased to be stable, or what amounts to the same
+thing is just becoming unstable, and the converse is true of the A + b
+family.  After passing the point of bifurcation A + a has become definitely
+unstable and A + b has become stable.  Hence the point of bifurcation is
+also a point of "exchange of stabilities between the two types."  (In order
+not to complicate unnecessarily this explanation of a general principle I
+have not stated fully all the cases that may occur.  Thus:  firstly, after
+bifurcation A + a may be an impossible type and A + a will then stop at
+this point; or secondly, A + b may have been an impossible type before
+bifurcation, and will only begin to be a real one after it; or thirdly,
+both A + a and A + b may be impossible after the point of bifurcation, in
+which case they coalesce and disappear.  This last case shows that types
+arise and disappear in pairs, and that on appearance or before
+disappearance one must be stable and the other unstable.)
+
+In nature it is of course only the stable types of motion which can persist
+for more than a short time.  Thus the task of the physical evolutionist is
+to determine the forms of bifurcation, at which he must, as it were, change
+carriages in the evolutionary journey so as always to follow the stable
+route.  He must besides be able to indicate some natural process which
+shall correspond in effect to the ideal arrangement of the several types of
+motion in families with gradually changing specific differences.  Although,
+as we shall see hereafter, it may frequently or even generally be
+impossible to specify with exactness the forms of bifurcation in the
+process of evolution, yet the conception is one of fundamental importance.
+
+The ideas involved in this sketch are no doubt somewhat recondite, but I
+hope to render them clearer to the non-mathematical reader by homologous
+considerations in other fields of thought (I considered this subject in my
+Presidential address to the British Association in 1905, "Report of the
+75th Meeting of the British Assoc." (S. Africa, 1905), London, 1906, page
+3.  Some reviewers treated my speculations as fanciful, but as I believe
+that this was due generally to misapprehension, and as I hold that
+homologous considerations as to stability and instability are really
+applicable to evolution of all sorts, I have thought it well to return to
+the subject in the present paper.), and I shall pass on thence to
+illustrations which will teach us something of the evolution of stellar
+systems.
+
+States or governments are organised schemes of action amongst groups of
+men, and they belong to various types to which generic names, such as
+autocracy, aristocracy or democracy, are somewhat loosely applied.  A
+definite type of government corresponds to one of our types of motion, and
+while retaining its type it undergoes a slow change as the civilisation and
+character of the people change, and as the relationship of the nation to
+other nations changes.  In the language used before, the government belongs
+to a family, and as time advances we proceed through the successive members
+of the family.  A government possesses a certain degree of stability--
+hardly measurable in numbers however--to resist disintegrating influences
+such as may arise from wars, famines, and internal dissensions.  This
+stability gradually rises to a maximum and gradually declines.  The degree
+of stability at any epoch will depend on the fitness of some leading
+feature of the government to suit the slowly altering circumstances, and
+that feature corresponds to the characteristic denoted by a in the physical
+problem.  A time at length arrives when the stability vanishes, and the
+slightest shock will overturn the government.  At this stage we have
+reached the crisis of a point of bifurcation, and there will then be some
+circumstance, apparently quite insignificant and almost unnoticed, which is
+such as to prevent the occurrence of anarchy.  This circumstance or
+condition is what we typified as b.  Insignificant although it may seem, it
+has started the government on a new career of stability by imparting to it
+a new type.  It grows in importance, the form of government becomes
+obviously different, and its stability increases.  Then in its turn this
+newly acquired stability declines, and we pass on to a new crisis or
+revolution.  There is thus a series of "points of bifurcation" in history
+at which the continuity of political history is maintained by means of
+changes in the type of government.  These ideas seem, to me at least, to
+give a true account of the history of states, and I contend that it is no
+mere fanciful analogy but a true homology, when in both realms of thought--
+the physical and the political--we perceive the existence of forms of
+bifurcation and of exchanges of stability.
+
+Further than this, I would ask whether the same train of ideas does not
+also apply to the evolution of animals?  A species is well adapted to its
+environment when the individual can withstand the shocks of famine or the
+attacks and competition of other animals; it then possesses a high degree
+of stability.  Most of the casual variations of individuals are
+indifferent, for they do not tell much either for or against success in
+life; they are small oscillations which leave the type unchanged.  As
+circumstances change, the stability of the species may gradually dwindle
+through the insufficiency of some definite quality, on which in earlier
+times no such insistent demands were made.  The individual animals will
+then tend to fail in the struggle for life, the numbers will dwindle and
+extinction may ensue.  But it may be that some new variation, at first of
+insignificant importance, may just serve to turn the scale.  A new type may
+be formed in which the variation in question is preserved and augmented;
+its stability may increase and in time a new species may be produced.
+
+At the risk of condemnation as a wanderer beyond my province into the
+region of biological evolution, I would say that this view accords with
+what I understand to be the views of some naturalists, who recognise the
+existence of critical periods in biological history at which extinction
+occurs or which form the starting-point for the formation of new species. 
+Ought we not then to expect that long periods will elapse during which a
+type of animal will remain almost constant, followed by other periods,
+enormously long no doubt as measured in the life of man, of acute struggle
+for existence when the type will change more rapidly?  This at least is the
+view suggested by the theory of stability in the physical universe.  (I
+make no claim to extensive reading on this subject, but refer the reader
+for example to a paper by Professor A.A.W. Hubrecht on "De Vries's theory
+of Mutations", "Popular Science Monthly", July 1904, especially to page
+213.)
+
+And now I propose to apply these ideas of stability to the theory of
+stellar evolution, and finally to illustrate them by certain recent
+observations of a very remarkable character.
+
+Stars and planets are formed of materials which yield to the enormous
+forces called into play by gravity and rotation.  This is obviously true if
+they are gaseous or fluid, and even solid matter becomes plastic under
+sufficiently great stresses.  Nothing approaching a complete study of the
+equilibrium of a heterogeneous star has yet been found possible, and we are
+driven to consider only bodies of simpler construction.  I shall begin
+therefore by explaining what is known about the shapes which may be assumed
+by a mass of incompressible liquid of uniform density under the influences
+of gravity and of rotation.  Such a liquid mass may be regarded as an ideal
+star, which resembles a real star in the fact that it is formed of
+gravitating and rotating matter, and because its shape results from the
+forces to which it is subject.  It is unlike a star in that it possesses
+the attributes of incompressibility and of uniform density.  The difference
+between the real and the ideal is doubtless great, yet the similarity is
+great enough to allow us to extend many of the conclusions as to ideal
+liquid stars to the conditions which must hold good in reality.  Thus with
+the object of obtaining some insight into actuality, it is justifiable to
+discuss an avowedly ideal problem at some length.
+
+The attraction of gravity alone tends to make a mass of liquid assume the
+shape of a sphere, and the effects of rotation, summarised under the name
+of centrifugal force, are such that the liquid seeks to spread itself
+outwards from the axis of rotation.  It is a singular fact that it is
+unnecessary to take any account of the size of the mass of liquid under
+consideration, because the shape assumed is exactly the same whether the
+mass be small or large, and this renders the statement of results much
+easier than would otherwise be the case.
+
+A mass of liquid at rest will obviously assume the shape of a sphere, under
+the influence of gravitation, and it is a stable form, because any
+oscillation of the liquid which might be started would gradually die away
+under the influence of friction, however small.  If now we impart to the
+whole mass of liquid a small speed of rotation about some axis, which may
+be called the polar axis, in such a way that there are no internal currents
+and so that it spins in the same way as if it were solid, the shape will
+become slightly flattened like an orange.  Although the earth and the other
+planets are not homogeneous they behave in the same way, and are flattened
+at the poles and protuberant at the equator.  This shape may therefore
+conveniently be described as planetary.
+
+If the planetary body be slightly deformed the forces of restitution are
+slightly less than they were for the sphere; the shape is stable but
+somewhat less so than the sphere.  We have then a planetary spheroid,
+rotating slowly, slightly flattened at the poles, with a high degree of
+stability, and possessing a certain amount of rotational momentum.  Let us
+suppose this ideal liquid star to be somewhere in stellar space far removed
+from all other bodies; then it is subject to no external forces, and any
+change which ensues must come from inside.  Now the amount of rotational
+momentum existing in a system in motion can neither be created nor
+destroyed by any internal causes, and therefore, whatever happens, the
+amount of rotational momentum possessed by the star must remain absolutely
+constant.
+
+A real star radiates heat, and as it cools it shrinks.  Let us suppose then
+that our ideal star also radiates and shrinks, but let the process proceed
+so slowly that any internal currents generated in the liquid by the cooling
+are annulled so quickly by fluid friction as to be insignificant; further
+let the liquid always remain at any instant incompressible and homogeneous.
+All that we are concerned with is that, as time passes, the liquid star
+shrinks, rotates in one piece as if it were solid, and remains
+incompressible and homogeneous.  The condition is of course artificial, but
+it represents the actual processes of nature as well as may be,
+consistently with the postulated incompressibility and homogeneity. 
+(Mathematicians are accustomed to regard the density as constant and the
+rotational momentum as increasing.  But the way of looking at the matter,
+which I have adopted, is easier of comprehension, and it comes to the same
+in the end.)
+
+The shrinkage of a constant mass of matter involves an increase of its
+density, and we have therefore to trace the changes which supervene as the
+star shrinks, and as the liquid of which it is composed increases in
+density.  The shrinkage will, in ordinary parlance, bring the weights
+nearer to the axis of rotation.  Hence in order to keep up the rotational
+momentum, which as we have seen must remain constant, the mass must rotate
+quicker.  The greater speed of rotation augments the importance of
+centrifugal force compared with that of gravity, and as the flattening of
+the planetary spheroid was due to centrifugal force, that flattening is
+increased; in other words the ellipticity of the planetary spheroid
+increases.
+
+As the shrinkage and corresponding increase of density proceed, the
+planetary spheroid becomes more and more elliptic, and the succession of
+forms constitutes a family classified according to the density of the
+liquid.  The specific mark of this family is the flattening or ellipticity.
+
+Now consider the stability of the system, we have seen that the spheroid
+with a slow rotation, which forms our starting-point, was slightly less
+stable than the sphere, and as we proceed through the family of ever
+flatter ellipsoids the stability continues to diminish.  At length when it
+has assumed the shape shown in a figure titled "Planetary spheroid just
+becoming unstable" (Fig. 2.) where the equatorial and polar axes are
+proportional to the numbers 1000 and 583, the stability has just
+disappeared.  According to the general principle explained above this is a
+form of bifurcation, and corresponds to the form denoted A.  The specific
+difference a of this family must be regarded as the excess of the
+ellipticity of this figure above that of all the earlier ones, beginning
+with the slightly flattened planetary spheroid.  Accordingly the specific
+difference a of the family has gradually diminished from the beginning and
+vanishes at this stage.
+
+According to Poincare's principle the vanishing of the stability serves us
+with notice that we have reached a figure of bifurcation, and it becomes
+necessary to inquire what is the nature of the specific difference of the
+new family of figures which must be coalescent with the old one at this
+stage.  This difference is found to reside in the fact that the equator,
+which in the planetary family has hitherto been circular in section, tends
+to become elliptic.  Hitherto the rotational momentum has been kept up to
+its constant value partly by greater speed of rotation and partly by a
+symmetrical bulging of the equator.  But now while the speed of rotation
+still increases (The mathematician familiar with Jacobi's ellipsoid will
+find that this is correct, although in the usual mode of exposition,
+alluded to above in a footnote, the speed diminishes.), the equator tends
+to bulge outwards at two diametrically opposite points and to be flattened
+midway between these protuberances.  The specific difference in the new
+family, denoted in the general sketch by b, is this ellipticity of the
+equator.  If we had traced the planetary figures with circular equators
+beyond this stage A, we should have found them to have become unstable, and
+the stability has been shunted off along the A + b family of forms with
+elliptic equators.
+
+This new series of figures, generally named after the great mathematician
+Jacobi, is at first only just stable, but as the density increases the
+stability increases, reaches a maximum and then declines.  As this goes on
+the equator of these Jacobian figures becomes more and more elliptic, so
+that the shape is considerably elongated in a direction at right angles to
+the axis of rotation.
+
+At length when the longest axis of the three has become about three times
+as long as the shortest (The three axes of the ellipsoid are then
+proportional to 1000, 432, 343.), the stability of this family of figures
+vanishes, and we have reached a new form of bifurcation and must look for a
+new type of figure along which the stable development will presumably
+extend.  Two sections of this critical Jacobian figure, which is a figure
+of bifurcation, are shown by the dotted lines in a figure titled "The
+'pear-shaped figure' and the Jocobian figure from which it is derived"
+(Fig. 3.) comprising two figures, one above the other:  the upper figure is
+the equatorial section at right angles to the axis of rotation, the lower
+figure is a section through the axis.
+
+Now Poincare has proved that the new type of figure is to be derived from
+the figure of bifurcation by causing one of the ends to be prolonged into a
+snout and by bluntening the other end.  The snout forms a sort of stalk,
+and between the stalk and the axis of rotation the surface is somewhat
+flattened.  These are the characteristics of a pear, and the figure has
+therefore been called the "pear-shaped figure of equilibrium."  The firm
+line shows this new type of figure, whilst, as already explained, the
+dotted line shows the form of bifurcation from which it is derived.  The
+specific mark of this new family is the protrusion of the stalk together
+with the other corresponding smaller differences.  If we denote this
+difference by c, while A + b denotes the Jacobian figure of bifurcation
+from which it is derived, the new family may be called A + b + c, and c is
+zero initially.  According to my calculations this series of figures is
+stable (M. Liapounoff contends that for constant density the new series of
+figures, which M. Poincare discovered, has less rotational momentum than
+that of the figure of bifurcation.  If he is correct, the figure of
+bifurcation is a limit of stable figures, and none can exist with stability
+for greater rotational momentum.  My own work seems to indicate that the
+opposite is true, and, notwithstanding M. Liapounoff's deservedly great
+authority, I venture to state the conclusions in accordance with my own
+work.), but I do not know at what stage of its development it becomes
+unstable.
+
+Professor Jeans has solved a problem which is of interest as throwing light
+on the future development of the pear-shaped figure, although it is of a
+still more ideal character than the one which has been discussed.  He
+imagines an INFINITELY long circular cylinder of liquid to be in rotation
+about its central axis.  The existence is virtually postulated of a demon
+who is always occupied in keeping the axis of the cylinder straight, so
+that Jeans has only to concern himself with the stability of the form of
+the section of the cylinder, which as I have said is a circle with the axis
+of rotation at the centre.  He then supposes the liquid forming the
+cylinder to shrink in diameter, just as we have done, and finds that the
+speed of rotation must increase so as to keep up the constancy of the
+rotational momentum.  The circularity of section is at first stable, but as
+the shrinkage proceeds the stability diminishes and at length vanishes. 
+This stage in the process is a form of bifurcation, and the stability
+passes over to a new series consisting of cylinders which are elliptic in
+section.  The circular cylinders are exactly analogous with our planetary
+spheroids, and the elliptic ones with the Jacobian ellipsoids.
+
+With further shrinkage the elliptic cylinders become unstable, a new form
+of bifurcation is reached, and the stability passes over to a series of
+cylinders whose section is pear-shaped.  Thus far the analogy is complete
+between our problem and Jeans's, and in consequence of the greater
+simplicity of the conditions, he is able to carry his investigation
+further.  He finds that the stalk end of the pear-like section continues to
+protrude more and more, and the flattening between it and the axis of
+rotation becomes a constriction.  Finally the neck breaks and a satellite
+cylinder is born.  Jeans's figure for an advanced stage of development is
+shown in a figure titled "Section of a rotating cylinder of liquid" (Fig.
+4.), but his calculations do not enable him actually to draw the state of
+affairs after the rupture of the neck.
+
+There are certain difficulties in admitting the exact parallelism between
+this problem and ours, and thus the final development of our pear-shaped
+figure and the end of its stability in a form of bifurcation remain hidden
+from our view, but the successive changes as far as they have been
+definitely traced are very suggestive in the study of stellar evolution.
+
+Attempts have been made to attack this problem from the other end.  If we
+begin with a liquid satellite revolving about a liquid planet and proceed
+backwards in time, we must make the two masses expand so that their density
+will be diminished.  Various figures have been drawn exhibiting the shapes
+of two masses until their surfaces approach close to one another and even
+until they just coalesce, but the discussion of their stability is not
+easy.  At present it would seem to be impossible to reach coalescence by
+any series of stable transformations, and if this is so Professor Jeans's
+investigation has ceased to be truly analogous to our problem at some
+undetermined stage.  However this may be this line of research throws an
+instructive light on what we may expect to find in the evolution of real
+stellar systems.
+
+In the second part of this paper I shall point out the bearing which this
+investigation of the evolution of an ideal liquid star may have on the
+genesis of double stars.
+
+II.
+
+There are in the heavens many stars which shine with a variable brilliancy.
+Amongst these there is a class which exhibits special peculiarities; the
+members of this class are generally known as Algol Variables, because the
+variability of the star Beta Persei or Algol was the first of such cases to
+attract the attention of astronomers, and because it is perhaps still the
+most remarkable of the whole class.  But the circumstances which led to
+this discovery were so extraordinary that it seems worth while to pause a
+moment before entering on the subject.
+
+John Goodricke, a deaf-mute, was born in 1764; he was grandson and heir of
+Sir John Goodricke of Ribston Hall, Yorkshire.  In November 1782, he noted
+that the brilliancy of Algol waxed and waned (It is said that Georg
+Palitzch, a farmer of Prohlis near Dresden, had about 1758 already noted
+the variability of Algol with the naked eye.  "Journ. Brit. Astron. Assoc."
+Vol. XV. (1904-5), page 203.), and devoted himself to observing it on every
+fine night from the 28th December 1782 to the 12th May 1783.  He
+communicated his observations to the Royal Society, and suggested that the
+variation in brilliancy was due to periodic eclipses by a dark companion
+star, a theory now universally accepted as correct.  The Royal Society
+recognised the importance of the discovery by awarding to Goodricke, then
+only 19 years of age, their highest honour, the Copley medal.  His later
+observations of Beta Lyrae and of Delta Cephei were almost as remarkable as
+those of Algol, but unfortunately a career of such extraordinary promise
+was cut short by death, only a fortnight after his election to the Royal
+Society.  ("Dict. of National Biography"; article Goodricke (John).  The
+article is by Miss Agnes Clerke.  It is strange that she did not then seem
+to be aware that he was a deaf-mute, but she notes the fact in her
+"Problems of Astrophysics", page 337, London, 1903.)
+
+It was not until 1889 that Goodricke's theory was verified, when it was
+proved by Vogel that the star was moving in an orbit, and in such a manner
+that it was only possible to explain the rise and fall in the luminosity by
+the partial eclipse of a bright star by a dark companion.
+
+The whole mass of the system of Algol is found to be half as great again as
+that of our sun, yet the two bodies complete their orbit in the short
+period of 2d 20h 48m 55s.  The light remains constant during each period,
+except for 9h 20m when it exhibits a considerable fall in brightness
+(Clerke, "Problems of Astrophysics" page 302 and chapter XVIII.); the curve
+which represents the variation in the light is shown in a figure titled
+"The light-curve and system of Beta Lyrae" (Fig. 7.).
+
+The spectroscope has enabled astronomers to prove that many stars, although
+apparently single, really consist of two stars circling around one another
+(If a source of light is approaching with a great velocity the waves of
+light are crowded together, and conversely they are spaced out when the
+source is receding.  Thus motion in the line of sight virtually produces an
+infinitesimal change of colour.  The position of certain dark lines in the
+spectrum affords an exceedingly accurate measurement of colour.  Thus
+displacements of these spectral lines enables us to measure the velocity of
+the source of light towards or away from the observer.); they are known as
+spectroscopic binaries.  Campbell of the Lick Observatory believes that
+about one star in six is a binary ("Astrophysical Journ." Vol. XIII. page
+89, 1901.  See also A. Roberts, "Nature", Sept. 12, 1901, page 468.); thus
+there must be many thousand such stars within the reach of our
+spectroscopes.
+
+The orientation of the planes of the orbits of binary stars appears to be
+quite arbitrary, and in general the star does not vary in brightness. 
+Amongst all such orbits there must be some whose planes pass nearly through
+the sun, and in these cases the eclipse of one of the stars by the other
+becomes inevitable, and in each circuit there will occur two eclipses of
+unequal intensities.
+
+It is easy to see that in the majority of such cases the two components
+must move very close to one another.
+
+The coincidence between the spectroscopic and the photometric evidence
+permits us to feel complete confidence in the theory of eclipses.  When
+then we find a star with a light-curve of perfect regularity and with a
+characteristics of that of Algol, we are justified in extending the theory
+of eclipses to it, although it may be too faint to permit of adequate
+spectroscopic examination.  This extension of the theory secures a
+considerable multiplication of the examples available for observation, and
+some 30 have already been discovered.
+
+Dr Alexander Roberts, of Lovedale in Cape Colony, truly remarks that the
+study of Algol variables "brings us to the very threshold of the question
+of stellar evolution."  ("Proc. Roy. Soc. Edinburgh", XXIV. Part II.
+(1902), page 73.)  It is on this account that I propose to explain in some
+detail the conclusion to which he and some other observers have been led.
+
+Although these variable stars are mere points of light, it has been proved
+by means of the spectroscope that the law of gravitation holds good in the
+remotest regions of stellar space, and further it seems now to have become
+possible even to examine the shapes of stars by indirect methods, and thus
+to begin the study of their evolution.  The chain of reasoning which I
+shall explain must of necessity be open to criticism, yet the explanation
+of the facts by the theory is so perfect that it is not easy to resist the
+conviction that we are travelling along the path of truth.
+
+The brightness of a star is specified by what is called its "magnitude." 
+The average brightness of all the stars which can just be seen with the
+naked eye defines the sixth magnitude.  A star which only gives two-fifths
+as much light is said to be of the seventh magnitude; while one which gives
+2 1/2 times as much light is of the fifth magnitude, and successive
+multiplications or divisions by 2 1/2 define the lower or higher
+magnitudes.  Negative magnitudes have clearly to be contemplated; thus
+Sirius is of magnitude minus 1.4, and the sun is of magnitude minus 26.
+
+The definition of magnitude is also extended to fractions; for example, the
+lights given by two candles which are placed at 100 feet and 100 feet 6
+inches from the observer differ in brightness by one-hundredth of a
+magnitude.
+
+A great deal of thought has been devoted to the measurement of the
+brightness of stars, but I will only describe one of the methods used, that
+of the great astronomer Argelander.  In the neighbourhood of the star under
+observation some half dozen standard stars are selected of known invariable
+magnitudes, some being brighter and some fainter than the star to be
+measured; so that these stars afford a visible scale of brightness. 
+Suppose we number them in order of increasing brightness from 1 to 6; then
+the observer estimates that on a given night his star falls between stars 2
+and 3, on the next night, say between 3 and 4, and then again perhaps it
+may return to between 2 and 3, and so forth.  With practice he learns to
+evaluate the brightness down to small fractions of a magnitude, even a
+hundredth part of a magnitude is not quite negligible.
+
+For example, in observing the star RR Centauri five stars were in general
+used for comparison by Dr Roberts, and in course of three months he secured
+thereby 300 complete observations.  When the period of the cycle had been
+ascertained exactly, these 300 values were reduced to mean values which
+appertained to certain mean places in the cycle, and a mean light-curve was
+obtained in this way.  Figures titled "Light curve of RR Centauri" (Fig. 5)
+and "The light-curve and system of Beta Lyrae" (Fig. 7) show examples of
+light curves.
+
+I shall now follow out the results of the observation of RR Centauri not
+only because it affords the easiest way of explaining these investigations,
+but also because it is one of the stars which furnishes the most striking
+results in connection with the object of this essay.  (See "Monthly notices
+R.A.S." Vol. 63, 1903, page 527.)  This star has a mean magnitude of about
+7 1/2, and it is therefore invisible to the naked eye.  Its period of
+variability is 14h 32m 10s.76, the last refinement of precision being of
+course only attained in the final stages of reduction.  Twenty-nine mean
+values of the magnitude were determined, and they were nearly equally
+spaced over the whole cycle of changes.  The black dots in Fig. 5 exhibit
+the mean values determined by Dr Roberts.  The last three dots on the
+extreme right are merely the same as the first three on the extreme left,
+and are repeated to show how the next cycle would begin.  The smooth dotted
+curve will be explained hereafter, but, by reference to the scale of
+magnitudes on the margins of the figure, it may be used to note that the
+dots might be brought into a perfectly smooth curve by shifting some few of
+the dots by about a hundredth of a magnitude.
+
+This light-curve presents those characteristics which are due to successive
+eclipses, but the exact form of the curve must depend on the nature of the
+two mutually eclipsing stars.  If we are to interpret the curve with all
+possible completeness, it is necessary to make certain assumptions as to
+the stars.  It is assumed then that the stars are equally bright all over
+their disks, and secondly that they are not surrounded by an extensive
+absorptive atmosphere.  This last appears to me to be the most dangerous
+assumption involved in the whole theory.
+
+Making these assumptions, however, it is found that if each of the
+eclipsing stars were spherical it would not be possible to generate such a
+curve with the closest accuracy.  The two stars are certainly close
+together, and it is obvious that in such a case the tidal forces exercised
+by each on the other must be such as to elongate the figure of each towards
+the other.  Accordingly it is reasonable to adopt the hypothesis that the
+system consists of a pair of elongated ellipsoids, with their longest axes
+pointed towards one another.  No supposition is adopted a priori as to the
+ratio of the two masses, or as to their relative size or brightness, and
+the orbit may have any degree of eccentricity.  These last are all to be
+determined from the nature of the light-curve.
+
+In the case of RR Centauri, however, Dr Roberts finds the conditions are
+best satisfied by supposing the orbit to be circular, and the sizes and
+masses of the components to be equal, while their luminosities are to one
+another in the ratio of 4 to 3.  As to their shapes he finds them to be so
+much elongated that they overlap, as exhibited in his figure titled "The
+shape of the star RR Centauri" (Fig. 6.).  The dotted curve shows a form of
+equilibrium of rotating liquid as computed by me some years before, and it
+was added for the sake of comparison.
+
+On turning back to Fig. 5 the reader will see in the smooth dotted curve
+the light variation which would be exhibited by such a binary system as
+this.  The curve is the result of computation and it is impossible not to
+be struck by the closeness of the coincidence with the series of black dots
+which denote the observations.
+
+It is virtually certain that RR Centauri is a case of an eclipsing binary
+system, and that the two stars are close together.  It is not of course
+proved that the figures of the stars are ellipsoids, but gravitation must
+deform them into a pair of elongated bodies, and, on the assumptions that
+they are not enveloped in an absorptive atmosphere and that they are
+ellipsoidal, their shapes must be as shown in the figure.
+
+This light-curve gives an excellent illustration of what we have reason to
+believe to be a stage in the evolution of stars, when a single star is
+proceeding to separate into a binary one.
+
+As the star is faint, there is as yet no direct spectroscopic evidence of
+orbital motion.  Let us turn therefore to the case of another star, namely
+V Puppis, in which such evidence does already exist.  I give an account of
+it, because it presents a peculiarly interesting confirmation of the
+correctness of the theory.
+
+In 1895 Pickering announced in the "Harvard Circular" No. 14 that the
+spectroscopic observations at Arequipa proved V Puppis to be a double star
+with a period of 3d 2h 46m.  Now when Roberts discussed its light-curve he
+found that the period was 1d 10h 54m 27s, and on account of this serious
+discrepancy he effected the reduction only on the simple assumption that
+the two stars were spherical, and thus obtained a fairly good
+representation of the light-curve.  It appeared that the orbit was circular
+and that the two spheres were not quite in contact.  Obviously if the stars
+had been assumed to be ellipsoids they would have been found to overlap, as
+was the case for RR Centauri.  ("Astrophysical Journ." Vol. XIII. (1901),
+page 177.)  The matter rested thus for some months until the spectroscopic
+evidence was re-examined by Miss Cannon on behalf of Professor Pickering,
+and we find in the notes on page 177 of Vol. XXVIII. of the "Annals of the
+Harvard Observatory" the following:  "A.G.C. 10534.  This star, which is
+the Algol variable V Puppis, has been found to be a spectroscopic binary. 
+The period 1d.454 (i.e. 1d 10h 54m) satisfies the observations of the
+changes in light, and of the varying separation of the lines of the
+spectrum.  The spectrum has been examined on 61 plates, on 23 of which the
+lines are double."  Thus we have valuable evidence in confirmation of the
+correctness of the conclusions drawn from the light-curve.  In the
+circumstances, however, I have not thought it worth while to reproduce Dr
+Roberts's provisional figure.
+
+I now turn to the conclusions drawn a few years previously by another
+observer, where we shall find the component stars not quite in contact. 
+This is the star Beta Lyrae which was observed by Goodricke, Argelander,
+Belopolsky, Schur, Markwick and by many others.  The spectroscopic method
+has been successfully applied in this case, and the component stars are
+proved to move in an orbit about one another.  In 1897, Mr. G.W. Myers
+applied the theory of eclipses to the light-curve, on the hypothesis that
+the stars are elongated ellipsoids, and he obtained the interesting results
+exhibited in Fig. 7. ("Astrophysical Journ." Vol. VII. (1898), page 1.)
+
+The period of Beta Lyrae is relatively long, being 12d 21h 47m, the orbit
+is sensibly eccentric, and the two spheroids are not so much elongated as
+was the case with RR Centauri.  The mass of the system is enormous, one of
+the two stars being 10 times and the other 21 times as heavy as our sun.
+
+Further illustrations of this subject might be given, but enough has been
+said to explain the nature of the conclusions which have been drawn from
+this class of observation.
+
+In my account of these remarkable systems the consideration of one very
+important conclusion has been purposely deferred.  Since the light-curve is
+explicable by eclipses, it follows that the sizes of the two stars are
+determinable relatively to the distance between them.  The period of their
+orbital motion is known, being identical with the complete period of the
+variability of their light, and an easy application of Kepler's law of
+periodic times enables us to compute the sum of the masses of the two stars
+divided by the cube of the distance between their centres.  Now the sizes
+of the bodies being known, the mean density of the whole system may be
+calculated.  In every case that density has been found to be much less than
+the sun's, and indeed the average of a number of mean densities which have
+been determined only amounts to one-eighth of that of the sun.  In some
+cases the density is extremely small, and in no case is it quite so great
+as half the solar density.
+
+It would be absurd to suppose that these stars can be uniform in density
+throughout, and from all that is known of celestial bodies it is probable
+that they are gaseous in their external parts with great condensation
+towards their centres.  This conclusion is confirmed by arguments drawn
+from the theory of rotating masses of liquid.  (See J.H. Jeans, "On the
+density of Algol variables", "Astrophysical Journ." Vol. XXII. (1905), page
+97.)
+
+Although, as already explained, a good deal is known about the shapes and
+the stability of figures consisting of homogeneous incompressible liquid in
+rotation, yet comparatively little has hitherto been discovered about the
+equilibrium of rotating gaseous stars.  The figures calculated for
+homogeneous liquid can obviously only be taken to afford a general
+indication of the kind of figure which we might expect to find in the
+stellar universe.  Thus the dotted curve in Fig. 5, which exhibits one of
+the figures which I calculated, has some interest when placed alongside the
+figures of the stars in RR Centauri, as computed from the observations, but
+it must not be accepted as the calculated form of such a system.  I have
+moreover proved more recently that such a figure of homogeneous liquid is
+unstable.  Notwithstanding this instability it does not necessarily follow
+that the analogous figure for compressible fluid is also unstable, as will
+be pointed out more fully hereafter.
+
+Professor Jeans has discussed in a paper of great ability the difficult
+problems offered by the conditions of equilibrium and of stability of a
+spherical nebula.  ("Phil. Trans. R.S." Vol. CXCIX. A (1902), page 1.  See
+also A. Roberts, "S. African Assoc. Adv. Sci." Vol. I. (1903), page 6.)  In
+a later paper ("Astrophysical Journ." Vol. XXII. (1905), page 97.), in
+contrasting the conditions which must govern the fission of a star into two
+parts when the star is gaseous and compressible with the corresponding
+conditions in the case of incompressible liquid, he points out that for a
+gaseous star (the agency which effects the separation will no longer be
+rotation alone; gravitation also will tend towards separation...From
+numerical results obtained in the various papers of my own,...I have been
+led to the conclusion that a gravitational instability of the kind
+described must be regarded as the primary agent at work in the actual
+evolution of the universe, Laplace's rotation playing only the secondary
+part of separating the primary and satellite after the birth of the
+satellite."
+
+It is desirable to add a word in explanation of the expression
+"gravitational instability" in this passage.  It means that when the
+concentration of a gaseous nebula (without rotation) has proceeded to a
+certain stage, the arrangement in spherical layers of equal density becomes
+unstable, and a form of bifurcation has been reached.  For further
+concentration concentric spherical layers become unstable, and the new
+stable form involves a concentration about two centres.  The first sign of
+this change is that the spherical layers cease to be quite concentric and
+then the layers of equal density begin to assume a somewhat pear-shaped
+form analogous to that which we found to occur under rotation for an
+incompressible liquid.  Accordingly it appears that while a sphere of
+liquid is stable a sphere of gas may become unstable.  Thus the conditions
+of stability are different in these two simple cases, and it is likely that
+while certain forms of rotating liquid are unstable the analogous forms for
+gas may be stable.  This furnishes a reason why it is worth while to
+consider the unstable forms of rotating liquid.
+
+There can I think be little doubt but that Jeans is right in looking to
+gravitational instability as the primary cause of fission, but when we
+consider that a binary system, with a mass larger than the sun's, is found
+to rotate in a few hours, there seems reason to look to rotation as a
+contributory cause scarcely less important than the primary one.
+
+With the present extent of our knowledge it is only possible to reconstruct
+the processes of the evolution of stars by means of inferences drawn from
+several sources.  We have first to rely on the general principles of
+stability, according to which we are to look for a series of families of
+forms, each terminating in an unstable form, which itself becomes the
+starting-point of the next family of stable forms.  Secondly we have as a
+guide the analogy of the successive changes in the evolution of ideal
+liquid stars; and thirdly we already possess some slender knowledge as to
+the equilibrium of gaseous stars.
+
+From these data it is possible to build up in outline the probable history
+of binary stars.  Originally the star must have been single, it must have
+been widely diffused, and must have been endowed with a slow rotation.  In
+this condition the strata of equal density must have been of the planetary
+form.  As it cooled and contracted the symmetry round the axis of rotation
+must have become unstable, through the effects of gravitation, assisted
+perhaps by the increasing speed of rotation.  (I learn from Professor Jeans
+that he now (December 1908) believes that he can prove that some small
+amount of rotation is necessary to induce instability in the symmetrical
+arrangement.)  The strata of equal density must then become somewhat pear-
+shaped, and afterwards like an hour-glass, with the constriction more
+pronounced in the internal than in the external strata.  The constrictions
+of the successive strata then begin to rupture from the inside
+progressively outwards, and when at length all are ruptured we have the
+twin stars portrayed by Roberts and by others.
+
+As we have seen, the study of the forms of equilibrium of rotating liquid
+is almost complete, and Jeans has made a good beginning in the
+investigation of the equilibrium of gaseous stars, but much more remains to
+be discovered.  The field for the mathematician is a wide one, and in
+proportion as the very arduous exploration of that field is attained so
+will our knowledge of the processes of cosmical evolution increase.
+
+From the point of view of observation, improved methods in the use of the
+spectroscope and increase of accuracy in photometry will certainly lead to
+a great increase in our knowledge within the next few years.  Probably the
+observational advance will be more rapid than that of theory, for we know
+how extraordinary has been the success attained within the last few years,
+and the theory is one of extreme difficulty; but the two ought to proceed
+together hand in hand.  Human life is too short to permit us to watch the
+leisurely procedure of cosmical evolution, but the celestial museum
+contains so many exhibits that it may become possible, by the aid of
+theory, to piece together bit by bit the processes through which stars pass
+in the course of their evolution.
+
+In the sketch which I have endeavoured to give of this fascinating subject,
+I have led my reader to the very confines of our present knowledge.  It is
+not much more than a quarter of a century since this class of observation
+has claimed the close attention of astronomers; something considerable has
+been discovered already and there seems scarcely a discernible limit to
+what will be known in this field a century from now.  Some of the results
+which I have set forth may then be shown to be false, but it seems
+profoundly improbable that we are being led astray by a Will-of-the-Wisp.
+
+
+XXIX.  THE EVOLUTION OF MATTER.
+
+By W.C.D. WHETHAM, M.A., F.R.S.
+Trinity College, Cambridge.
+
+The idea of evolution in the organic world, made intelligible by the work
+of Charles Darwin, has little in common with the recent conception of
+change in certain types of matter.  The discovery that a process of
+disintegration may take place in some at least of the chemical atoms,
+previously believed to be indestructible and unalterable, has modified our
+view of the physical universe, even as Darwin's scheme of the mode of
+evolution changed the trend of thought concerning the organic world.  Both
+conceptions have in common the idea of change throughout extended realms of
+space and time, and, therefore, it is perhaps not unfitting that some
+account of the most recent physical discoveries should be included in the
+present volume.
+
+The earliest conception of the evolution of matter is found in the
+speculation of the Greeks.  Leucippus and Democritus imagined unchanging
+eternal atoms, Heracleitus held that all things were in a continual state
+of flux--Panta rei.
+
+But no one in the Ancient World--no one till quite modern times--could
+appreciate the strength of the position which the theory of the evolution
+of matter must carry before it wins the day.  Vague speculation, even by
+the acute minds of philosophers, is of little use in physical science
+before experimental facts are available.  The true problems at issue cannot
+even be formulated, much less solved, till the humble task of the observer
+and experimenter has given us a knowledge of the phenomena to be explained.
+
+It was only through the atomic theory, at first apparently diametrically
+opposed to it, that the conception of evolution in the physical world was
+to gain an established place.  For a century the atomic theory, when put
+into a modern form by Dalton, led farther and farther away from the idea of
+change in matter.  The chemical elements seemed quite unalterable, and the
+atoms, of which each element in modern view is composed, bore to Clerk
+Maxwell, writing about 1870, "the stamp of manufactured articles" exactly
+similar in kind, unchanging, eternal.
+
+Nevertheless throughout these years, on the whole so unfavourable to its
+existence, there persisted the idea of a common origin of the distinct
+kinds of matter known to chemists.  Indeed, this idea of unity in substance
+in nature seems to accord with some innate desire or intimate structure of
+the human mind.  As Mr Arthur Balfour well puts it, "There is no a priori
+reason that I know of for expecting that the material world should be a
+modification of a single medium, rather than a composite structure built
+out of sixty or seventy elementary substances, eternal and eternally
+different.  Why then should we feel content with the first hypothesis and
+not with the second?  Yet so it is.  Men of science have always been
+restive under the multiplication of entities.  They have eagerly watched
+for any sign that the different chemical elements own a common origin, and
+are all compounded out of some primordial substance.  Nor, for my part, do
+I think that such instincts should be ignored...that they exist is certain;
+that they modify the indifferent impartiality of pure empiricism can hardly
+be denied."  ("Report of the 74th Meeting of the British Association"
+(Presidential Address, Cambridge 1904), page 9, London, 1905.)
+
+When Dalton's atomic theory had been in existence some half century, it was
+noted that certain numerical relations held good between the atomic weights
+of elements chemically similar to one another.  Thus the weight (88) of an
+atom of strontium compared with that of hydrogen as unity, is about the
+mean of those of calcium (40) and barium (137).  Such relations, in this
+and other chemical groups, were illustrated by Beguyer de Chancourtois in
+1862 by the construction of a spiral diagram in which the atomic weights
+are placed in order round a cylinder and elements chemically similar are
+found to fall on vertical lines.
+
+Newlands seems to have been the first to see the significance of such a
+diagram.  In his "law of octaves," formulated in 1864, he advanced the
+hypothesis that, if arranged in order of rising atomic weight, the elements
+fell into groups, so that each eighth element was chemically similar. 
+Stated thus, the law was too definite; no room was left for newly-
+discovered elements, and some dissimilar elements were perforce grouped
+together.
+
+But in 1869 Mendeleeff developed Newland's hypothesis in a form that
+attracted at once general attention.  Placing the elements in order of
+rising atomic weight, but leaving a gap where necessary to bring similar
+elements into vertical columns, he obtained a periodic table with natural
+vacancies to be filled as new elements were discovered, and with a certain
+amount of flexibility at the ends of the horizontal lines.  From the
+position of the vacancies, the general chemical and physical properties of
+undiscovered elements could be predicted, and the success of such
+predictions gave a striking proof of the usefulness of Mendeleeff's
+generalisation.
+
+When the chemical and physical properties of the elements were known to be
+periodic functions of their atomic weights, the idea of a common origin and
+common substance became much more credible.  Differences in atomic weight
+and differences in properties alike might reasonably be explained by the
+differences in the amount of the primordial substance present in the
+various atoms; an atom of oxygen being supposed to be composed of sixteen
+times as much stuff as the atom of hydrogen, but to be made of the same
+ultimate material.  Speculations about the mode of origin of the elements
+now began to appear, and put on a certain air of reality.  Of these
+speculations perhaps the most detailed was that of Crookes, who imagined an
+initial chaos of a primordial medium he named protyle, and a process of
+periodic change in which the chemical elements successively were
+precipitated.
+
+From another side too, suggestions were put forward by Sir Norman Lockyer
+and others that the differences in spectra observed in different classes of
+stars, and produced by different conditions in the laboratory, were to be
+explained by changes in the structure of the vibrating atoms.
+
+The next step in advance gave a theoretical basis for the idea of a common
+structure of matter, and was taken in an unexpected direction.  Clerk
+Maxwell's electromagnetic theory of light, accepted in England, was driven
+home to continental minds by the confirmatory experiments of Hertz, who in
+1888 detected and measured the electromagnetic waves that Maxwell had
+described twenty years earlier.  But, if light be an electromagnetic
+phenomenon, the light waves radiated by hot bodies must take their origin
+in the vibrations of electric systems.  Hence within the atoms must exist
+electric charges capable of vibration.  On these lines Lorentz and Larmor
+have developed an electronic theory of matter, which is imagined in its
+essence to be a conglomerate of electric charges, with electro-magnetic
+inertia to explain mechanical inertia.  (Larmor, "Aether and Matter",
+Cambridge, 1900.)  The movement of electric charges would be affected by a
+magnetic field, and hence the discovery by Zeeman that the spectral lines
+of sodium were doubled by a strong magnetic force gave confirmatory
+evidence to the theory of electrons.
+
+Then came J.J. Thomson's great discovery of minute particles, much smaller
+than any chemical atom, forming a common constituent of many different
+kinds of matter.  (Thomson, "Conduction of Electricity through Gases" (2nd
+edition), Cambridge, 1906.)  If an electric discharge be passed between
+metallic terminals through a glass vessel containing air at very low
+pressure, it is found that rectilinear rays, known as cathode rays, proceed
+from the surface of the cathode or negative terminal.  Where these rays
+strike solid objects, they give rise to the Rontgen rays now so well known;
+but it is with the cathode rays themselves that we are concerned.  When
+they strike an insulated conductor, they impart to it a negative charge,
+and Thomson found that they were deflected from their path both by magnetic
+and electric forces in the direction in which negatively electrified
+particles would be deflected.  Cathode rays then were accepted as flights
+of negatively charged particles, moving with high velocities.  The electric
+and magnetic deflections give two independent measurements which may be
+made on a cathode ray, and both the deflections involve theoretically three
+unknown quantities, the mass of the particles, their electric charge and
+their velocity.  There is strong cumulative evidence that all such
+particles possess the same charge, which is identical with that associated
+with a univalent atom in electrolytic liquids.  The number of unknown
+quantities was thus reduced to two--the mass and the velocity.  The
+measurement of the magnetic and electric deflections gave two independent
+relations between the unknowns, which could therefore be determined.  The
+velocities of the cathode ray particles were found to vary round a value
+about one-tenth that of light, but the mass was found always to be the same
+within the limits of error, whatever the nature of the terminals, of the
+residual gas in the vessel, and of the conditions of the experiment.  The
+mass of a cathode ray particle, or corpuscle, as Thomson, adopting Newton's
+name, called it, is about the eight-hundredth part of the mass of a
+hydrogen atom.
+
+These corpuscles, found in so many different kinds of substance, are
+inevitably regarded as a common constituent of matter.  They are associated
+each with a unit of negative electricity.  Now electricity in motion
+possesses electromagnetic energy, and produces effects like those of
+mechanical inertia.  In other words, an electric charge possesses mass, and
+there is evidence to show that the effective mass of a corpuscle increases
+as its velocity approaches that of light in the way it would do if all its
+mass were electromagnetic.  We are led therefore to regard the corpuscle
+from one aspect as a disembodied charge of electricity, and to identify it
+with the electron of Lorentz and Larmor.
+
+Thus, on this theory, matter and electricity are identified; and a great
+simplification of our conception of the physical structure of Nature is
+reached.  Moreover, from our present point of view, a common basis for
+matter suggests or implies a common origin, and a process of development
+possibly intelligible to our minds.  The idea of the evolution of matter
+becomes much more probable.
+
+The question of the nature and physical meaning of a corpuscle or electron
+remains for consideration.  On the hypothesis of a universal luminiferous
+aether, Larmor has suggested a centre of aethereal strain "a place where
+the continuity of the medium has been broken and cemented together again
+(to use a crude but effective image) without accurately fitting the parts,
+so that there is a residual strain all round the place."  (Larmor, loc.
+cit.)  Thus he explains in quasi-mechanical terms the properties of an
+electron.  But whether we remain content for the time with our
+identification of matter and electricity, or attempt to express both of
+them in terms of hypothetical aether, we have made a great step in advance
+on the view that matter is made up of chemical atoms fundamentally distinct
+and eternally isolated.
+
+Such was the position when the phenomena of radio-activity threw a new
+light on the problem, and, for the first time in the history of science,
+gave definite experimental evidence of the transmutation of matter from one
+chemical element to another.
+
+In 1896 H. Becquerel discovered that compounds of the metal uranium
+continually emitted rays capable of penetrating opaque screens and
+affecting photographic plates.  Like cathode and Rontgen rays, the rays
+from uranium make the air through which they pass a conductor of
+electricity, and this property gives the most convenient method of
+detecting the rays and of measuring their intensity.  An electroscope may
+be made of a strip of gold-leaf attached to an insulated brass plate and
+confined in a brass vessel with glass windows.  When the gold-leaf is
+electrified, it is repelled from the similarly electrified brass plate, and
+the angle at which it stands out measures the electrification.  Such a
+system, if well insulated, holds its charge for hours, the leakage of
+electricity through the air being very slow.  But, if radio-active
+radiation reach the air within, the gold-leaf falls, and the rate of its
+fall, as watched through a microscope with a scale in the eye-piece,
+measures the intensity of the radiation.  With some form of this simple
+instrument, or with the more complicated quadrant electrometer, most radio-
+active measurements have been made.
+
+It was soon discovered that the activity of uranium compounds was
+proportional to the amount of uranium present in them.  Thus radio-activity
+is an atomic property dependent on the amount of an element and independent
+of its state of chemical combination.
+
+In a search for radio-activity in different minerals, M. and Mme Curie
+found a greater effect in pitch-blende than its contents of uranium
+warranted, and, led by the radio-active property alone, they succeeded, by
+a long series of chemical separations, in isolating compounds of a new and
+intensely radio-active substance which they named radium.
+
+Radium resembles barium in its chemical properties, and is precipitated
+with barium in the ordinary course of chemical analysis.  It is separated
+by a prolonged course of successive crystallisation, the chloride of radium
+being less soluble than that of barium, and therefore sooner separated from
+an evaporating solution.  When isolated, radium chloride has a composition,
+which, on the assumption that one atom of metal combines with two of
+chlorine as in barium chloride, indicates that the relative weight of the
+atom of radium is about 225.  As thus prepared, radium is a well-marked
+chemical element, forming a series of compounds analogous to those of
+barium and showing a characteristic line spectrum.  But, unlike most other
+chemical elements, it is intensely radio-active, and produces effects some
+two million times greater than those of uranium.
+
+In 1899 E. Rutherford, then of Montreal, discovered that the radiation from
+uranium, thorium and radium was complex.  (Rutherford, "Radio-activity"
+(2nd edition), Cambridge, 1905.)  Three types of rays were soon
+distinguished.  The first, named by Rutherford alpha-rays, are absorbed by
+thin metal foil or a few centimetres of air.  When examined by measurements
+of the deflections caused by magnetic and electric fields, the alpha-rays
+are found to behave as would positively electrified particles of the
+magnitude of helium atoms possessing a double ionic charge and travelling
+with a velocity about one-tenth that of light.  The second or beta type of
+radiation is much more penetrating.  It will pass through a considerable
+thickness of metallic foil, or many centimetres of air, and still affect
+photographic plates or discharge electroscopes.  Magnetic and electric
+forces deflect beta-rays much more than alpha-rays, indicating that,
+although the speed is greater, approaching in some cases within five per
+cent. that of light, the mass is very much less.  The beta-rays must be
+streams of particles, identical with those of cathode rays, possessing the
+minute mass of J.J. Thomson's corpuscle, some eight-hundredth part of that
+of a hydrogen atom.  A third or gamma type of radiation was also detected. 
+More penetrating even than beta-rays, the gamma-rays have never been
+deflected by any magnetic or electric force yet applied.  Like Rontgen
+rays, it is probable that gamma-rays are wave-pulses in the luminiferous
+aether, though the possibility of explaining them as flights of non-
+electrified particles is before the minds of some physicists.
+
+Still another kind of radiation has been discovered more recently by
+Thomson, who has found that in high vacua, rays become apparent which are
+absorbed at once by air at any ordinary pressure.
+
+The emission of all these different types of radiation involves a continual
+drain of energy from the radio-active body.  When M. and Mme Curie had
+prepared as much as a gramme of radium chloride, the energy of the
+radiation became apparent as an evolution of heat.  The radium salt itself,
+and the case containing it, absorbed the major part of the radiation, and
+were thus maintained at a temperature measurably higher than that of the
+surroundings.  The rate of thermal evolution was such that it appeared that
+one gramme of pure radium must emit about 100 gramme-calories of heat in an
+hour.  This observation, naturally as it follows from the phenomena
+previously discovered, first called attention to the question of the source
+of the energy which maintains indefinitely and without apparent diminution
+the wonderful stream of radiation proceeding from a radio-active substance. 
+In the solution of this problem lies the point of the present essay.
+
+In order to appreciate the evidence which bears on the question we must now
+describe two other series of phenomena.
+
+It is a remarkable fact that the intensity of the radiation from a radio-
+active body is independent of the external conditions of temperature,
+pressure, etc. which modify so profoundly almost all other physical and
+chemical processes.  Exposure to the extreme cold of liquid air, or to the
+great heat of a furnace, leaves the radio-activity of a substance
+unchanged, apparent exceptions to this statement having been traced to
+secondary causes.
+
+Then, it is found that radio-activity is always accompanied by some
+chemical change; a new substance always appears as the parent substance
+emits these radiations.  Thus by chemical reactions it is possible to
+separate from uranium and thorium minute quantities of radio-active
+materials to which the names of uranium-X and thorium-X have been given. 
+These bodies behave differently from their parents uranium and thorium, and
+show all the signs of distinct chemical individuality.  They are strongly
+radio-active, while, after the separation, the parents uranium and thorium
+are found to have lost some of their radio-activity.  If the X-substances
+be kept, their radio-activity decays, while that of the uranium or thorium
+from which they were obtained gradually rises to the initial value it had
+before the separation.  At any moment, the sum of the radio-activity is
+constant, the activity lost by the product being equal to that gained by
+the parent substance.  These phenomena are explained if we suppose that the
+X-product is slowly produced in the substance of the parent, and decays at
+a constant rate.  Uranium, as usually seen, contains a certain amount of
+uranium-X, and its radio-activity consists of two parts--that of the
+uranium itself, and that of the X product.  When the latter is separated by
+means of its chemical reactions, its radio-activity is separated also, and
+the rates of decay and recovery may be examined.
+
+Radium and thorium, but not uranium, give rise to radio-active gases which
+have been called emanations.  Rutherford has shown that their radio-
+activity, like that of the X products, suffers decay, while the walls of
+the vessel in which the emanation is confined, become themselves radio-
+active.  If washed with certain acids, however, the walls lose their
+activity, which is transferred to the acid, and can be deposited by
+evaporation from it on to a solid surface.  Here again it is clear that the
+emanation gives rise to a radio-active substance which clings to the walls
+of the vessel, and is soluble in certain liquids, but not in others.
+
+We shall return to this point, and trace farther the history of the radio-
+active matter.  At present we wish to emphasise the fact that, as in other
+cases, the radio-activity of the emanation is accompanied by the appearance
+of a new kind of substance with distinct chemical properties.
+
+We are now in a position to consider as a whole the evidence on the
+question of the source of radio-active energy.
+
+(1)  Radio-activity is accompanied by the appearance of new chemical
+substances.  The energy liberated is therefore probably due to the
+associated chemical change.  (2)  The activity of a series of compounds is
+found to accompany the presence of a radio-active element, the activity of
+each compound depends only on the contents of the element, and is
+independent of the nature of its combination.  Thus radio-activity is a
+property of the element, and is not affected by its state of isolation or
+chemical combination. (3)  The radio-activity of a simple transient product
+decays in a geometrical progression, the loss per second being proportional
+to the mass of substance still left at the moment, and independent of its
+state of concentration or dilution.  This type of reaction is well known in
+chemistry to mark a mono-molecular change, where each molecule is
+dissociated or altered in structure independently.  If two or more
+molecules were concerned simultaneously, the rate of reaction would depend
+on the nearness of the molecules to each other, that is, to the
+concentration of the material.  (4)  The amount of energy liberated by the
+change of a given mass of material far transcends the amount set free by
+any known ordinary chemical action.  The activity of radium decays so
+slowly that it would not sink to half its initial value in less than some
+two thousand years, and yet one gramme of radium emits about 100 calories
+of heat during each hour of its existence.
+
+The energy of radio-activity is due to chemical change, but clearly to no
+chemical change hitherto familiar to science.  It is an atomic property,
+characteristic of a given element, and the atoms undergo the change
+individually, not by means of interaction among each other.  The conclusion
+is irresistible that we are dealing with a fundamental change in the
+structure of the individual atoms, which, one by one, are dissociating into
+simpler parts.  We are watching the disintegration of the "atoms" of the
+chemist, hitherto believed indestructible and eternal, and measuring the
+liberation of some of the long-suspected store of internal atomic energy. 
+We have stumbled on the transmutation dreamed by the alchemist, and
+discovered the process of a veritable evolution of matter.
+
+The transmutation theory of radio-activity was formulated by Rutherford
+(Rutherford, "Radio-activity" (2nd edition), Cambridge, 1905, page 307.)
+and Soddy in 1903.  By its light, all recent work on the subject has been
+guided; it has stood the supreme test of a hypothesis, and shown power to
+suggest new investigations and to co-ordinate and explain them, when
+carried out.  We have summarised the evidence which led to the conception
+of the theory; we have now to consider the progress which has been made in
+tracing the successive disintegration of radio-active atoms.
+
+Soon after the statement of the transmutation theory, a striking
+verification of one of its consequences appeared.  The measurement of the
+magnetic and electric deflection of the alpha-rays suggested to Rutherford
+the idea that the stream of projectiles of which they consisted was a
+flight of helium atoms.  Ramsay and Soddy, confining a minute bubble of
+radium emanation in a fine glass tube, were able to watch the development
+of the helium spectrum as, day by day, the emanation decayed.  By isolating
+a very narrow pencil of alpha-rays, and watching through a microscope their
+impact on a fluorescent screen, Rutherford has lately counted the
+individual alpha-projectiles, and confirmed his original conclusion that
+their mass corresponded to that of helium atoms and their charge to double
+that on a univalent atom.  ("Proc. Roy. Soc." A, page 141, 1908.)  Still
+more recently, he has collected the alpha-particles shot through an
+extremely thin wall of glass, and demonstrated by direct spectroscopic
+evidence the presence of helium.  ("Phil. Mag." February 1909.)
+
+But the most thorough investigation of a radio-active pedigree is found in
+Rutherford's classical researches on the successive disintegration products
+of radium, in order to follow the evidence on which his results are
+founded, we must describe more fully the process of decay of the activity
+of a simple radio-active substance.  The decay of activity of the body
+known as uranium-X is shown in a falling curve (Fig. 1.).  It will be seen
+that, in each successive 22 days, the activity falls to half the value it
+possessed at the beginning.
+
+This change in a geometrical progression is characteristic of simple radio-
+active processes, and can be expressed mathematically by a simple
+exponential formula.
+
+As we have said above, solid bodies exposed to the emanations of radium or
+thorium become coated with a radio-active deposit.  The rate of decay of
+this activity depends on the time of exposure to the emanation, and does
+not always show the usual simple type of curve.  Thus the activity of a rod
+exposed to radium emanation for 1 minute decays in accordance with a curve
+(Fig. 2) which represents the activity as measured by the alpha-rays.  If
+the electroscope be screened from the alpha-rays, it is found that the
+activity of the rod in beta- an gamma-rays increases for some 35 minutes
+and then diminishes (Fig. 3.).
+
+These complicated relations have been explained satisfactorily and
+completely by Rutherford on the hypothesis of successive changes of the
+radio-active matter into one new body after another.  (Rutherford, "Radio-
+activity" (2nd edition), Cambridge, 1905, page 379.)  The experimental
+curve represents the resultant activity of all the matter present at a
+given moment, and the process of disentangling the component effects
+consists in finding a number of curves, which express the rise and fall of
+activity of each kind of matter as it is produced and decays, and, fitted
+together, give the curve of the experiments.
+
+Other methods of investigation also are open.  They have enabled Rutherford
+to complete the life-history of radium and its products, and to clear up
+doubtful points left by the analysis of the curves.  By the removal of the
+emanation, the activity of radium itself has been shown to consist solely
+of alpha-rays.  This removal can be effected by passing air through the
+solution of a radium salt.  The emanation comes away, and the activity of
+the deposit which it leaves behind decays rapidly to a small fraction of
+its initial value.  Again, some of the active deposits of the emanation are
+more volatile than others, and can be separated from them by the agency of
+heat.
+
+From such evidence Rutherford has traced a long series of disintegration
+products of radium, all but the first of which exist in much too minute
+quantities to be detected otherwise than by their radio-activities. 
+Moreover, two of these products are not themselves appreciably radio-
+active, though they are born from radio-active parents, and give rise to a
+series of radio-active descendants.  Their presence is inferred from such
+evidence as the rise of beta and gamma radio-activity in the solid newly
+deposited by the emanation; this rise measuring the growth of the first
+radio-active offspring of one of the non-active bodies.  Some of the radium
+products give out alpha-rays only, one beta- and gamma-rays, while one
+yields all three types of radiation.  The pedigree of the radium family may
+be expressed in the following table, the time noted in the second column
+being the time required for a given quantity to be half transformed into
+its next derivative.
+
+           Time of half      Radio-       Properties
+           decay             activity    
+
+Radium     About 2600 years  alpha rays   Element chemically analogous
+                                          to barium.
+>
+Emanation  3.8 days          alpha rays   Chemically inert gas;
+                                           condenses at -150 deg C.
+>
+Radium-A   3 minutes         alpha rays   Behaves as a solid deposited on
+                                           surfaces; concentrated on a 
+                                           negative electrode.
+>
+Radium-B   21 minutes        no rays      Soluble in strong acids;
+                                           volatile at a white heat; more
+                                           volatile than A or C.
+>
+Radium-C   28 minutes        alpha, beta, Soluble in strong acids; less
+                             gamma rays    volatile than B.
+>
+Radium-D   about 40 years    no rays      Soluble in strong acids; volatile
+                                           below 1000 deg C.
+>
+Radium-E   6 days            beta, gamma  Non-volatile at 1000 deg C.
+                             rays
+>
+Radium-F   143 days          alpha rays   Volatile at 1000 deg C.
+                                           Deposited from solution on a
+                                           bismuth plate.
+
+Of these products, A, B, and C constitute that part of the active deposit
+of the emanation which suffers rapid decay and nearly disappears in a few
+hours.  Radium-D, continually producing its short-lived descendants E and
+F, remains for years on surfaces once exposed to the emanation, and makes
+delicate radio-active researches impossible in laboratories which have been
+contaminated by an escape of radium emanation.
+
+A somewhat similar pedigree has been made out in the case of thorium.  Here
+thorium-X is interposed between thorium and its short-lived emanation,
+which decays to half its initial quantity in 54 seconds.  Two active
+deposits, thorium A and B, arise successively from the emanation.  In
+uranium, we have the one obvious derivative uranium-X, and the question
+remains whether this one descent can be connected with any other individual
+or family.  Uranium is long-lived, and emits only alpha-rays.  Uranium-X
+decays to half value in 22 days, giving out beta- and gamma-rays.  Since
+our evidence goes to show that radio-activity is generally accompanied by
+the production of new elements, it is natural to search for the substance
+of uranium-X in other forms, and perhaps under other names, rather than to
+surrender immediately our belief in the conservation of matter.
+
+With this idea in mind we see at once the significance of the constitution
+of uranium minerals.  Formed in the remote antiquity of past geological
+ages, these minerals must become store-houses of all the products of
+uranium except those which may have escaped as gases or possibly liquids. 
+Even gases may be expected to some extent to be retained by occlusion. 
+Among the contents of uranium minerals, then, we may look for the
+descendants of the parent uranium.  If the descendants are permanent or
+more long-lived than uranium, they will accumulate continually.  If they
+are short-lived, they will accumulate at a steady rate till enough is
+formed for the quantity disintegrating to be equal to the quantity
+developed.  A state of mobile equilibrium will then be reached, and the
+amount of the product will remain constant.  This constant amount of
+substance will depend only on the amount of uranium which is its source,
+and, for different minerals, if all the product is retained, the quantity
+of the product will be proportional to the quantity of uranium.  In a
+series of analyses of uranium minerals, therefore, we ought to be able to
+pick out its more short-lived descendants by seeking for instances of such
+proportionality.
+
+Now radium itself is a constituent of uranium minerals, and two series of
+experiments by R.J. Strutt and B.B. Boltwood have shown that the content of
+radium, as measured by the radio-activity of the emanation, is directly
+proportional to the content of uranium.  (Strutt, "Proc. Roy. Soc." A,
+February 1905; Boltwood, "Phil. Mag." April, 1905.)  In Boltwood's
+investigation, some twenty minerals, with amounts of uranium varying from
+that in a specimen of uraninite with 74.65 per cent., to that in a monazite
+with 0.30 per cent., gave a ratio of uranium to radium, constant within
+about one part in ten.
+
+The conclusion is irresistible that radium is a descendant of uranium,
+though whether uranium is its parent or a more remote ancestor requires
+further investigation by the radio-active genealogist.  On the hypothesis
+of direct parentage, it is easy to calculate that the amount of radium
+produced in a month by a kilogramme of a uranium salt would be enough to be
+detected easily by the radio-activity of its emanation.  The investigation
+has been attempted by several observers, and the results, especially those
+of a careful experiment of Boltwood, show that from purified uranium salts
+the growth of radium, if appreciable at all, is much less than would be
+found if the radium was the first product of change of the uranium.  It is
+necessary, therefore, to look for one or more intermediate substances.
+
+While working in 1899 with the uranium residues used by M. and Mme Curie
+for the preparation of radium, Debierne discovered and partially separated
+another radio-active element which he called actinium.  It gives rise to an
+intermediate product actinium-X, which yields an emanation with the short
+half-life of 3.9 seconds.  The emanation deposits two successive
+disintegration products actinium-A and actinium-B.
+
+Evidence gradually accumulated that the amounts of actinium in radio-active
+minerals were, roughly at any rate, proportional to the amounts of uranium. 
+This result pointed to a lineal connection between them, and led Boltwood
+to undertake a direct attack on the problem.  Separating a quantity of
+actinium from a kilogramme of ore, Boltwood observed a growth of 8.5 x (10
+to the power -9) gramme of radium in 193 days, agreeing with that indicated
+by theory within the limits of experimental error.  ("American Journal of
+Science", December, 1906.)  We may therefore insert provisionally actinium
+and its series of derivatives between uranium and radium in the radio-
+active pedigree.
+
+Turning to the other end of the radium series we are led to ask what
+becomes of radium-F when in turn it disintegrates?  What is the final non-
+active product of the series of changes we have traced from uranium through
+actinium and radium?
+
+One such product has been indicated above.  The alpha-ray particles appear
+to possess the mass of helium atoms, and the growth of helium has been
+detected by its spectrum in a tube of radium emanation.  Moreover, helium
+is found occluded in most if not all radio-active minerals in amount which
+approaches, but never exceeds, the quantity suggested by theory.  We may
+safely regard such helium as formed by the accumulation of alpha-ray
+particles given out by successive radio-active changes.
+
+In considering the nature of the residue left after the expulsion of the
+five alpha-particles, and the consequent passage of radium to radium-F we
+are faced by the fact that lead is a general constituent of uranium
+minerals.  Five alpha-particles, each of atomic weight 4, taken from the
+atomic weight (about 225) of radium gives 205--a number agreeing fairly
+well with the 207 of lead.  Since lead is more permanent than uranium, it
+must steadily accumulate, no radio-active equilibrium will be reached, and
+the amount of lead will depend on the age of the mineral as well as on the
+quantity of uranium present in it.  In primary minerals from the same
+locality, Boltwood has shown that the contents of lead are proportional to
+the amounts of uranium, while, accepting this theory, the age of minerals
+with a given content of uranium may be calculated from the amount of lead
+they contain.  The results vary from 400 to 2000 million years.  ("American
+Journal of Science", October, 1905, and February, 1907.)
+
+We can now exhibit in tabular form the amazing pedigree of radio-active
+change shown by this one family of elements.  An immediate descent is
+indicated by >, while one which may either be immediate or involve an
+intermediate step is shown by ....  No place is found in this pedigree for
+thorium and its derivatives.  They seem to form a separate and independent
+radio-active family.
+
+                    Atomic Weight  Time of half     Radio-Activity
+                                      decay
+
+Uranium               238.5                         alpha
+>
+Uranium-X             ?            22 days          beta, gamma
+...
+Actinium              ?            ?                no rays
+>
+Actinium-X            ?            10.2 days        alpha (beta, gamma)
+>
+Actinium Emanation    ?            3.9 seconds      alpha
+>
+Actinium-A            ?            35.7 minutes     no rays
+>
+Actinium-B            ?            2.15 minutes      alpha, beta, gamma
+...
+Radium                225          about 2600 years  alpha
+>
+Radium Emanation      ?            3.8 days          alpha
+>
+Radium-A              ?            3 minutes         alpha
+>
+Radium-B              ?            21 minutes        no rays
+>
+Radium-C              ?            28 minutes        alpha, beta, gamma
+>
+Radium-D              ?            about 40 years    no rays
+>
+Radium-E              ?            6 days            beta (gamma)
+>
+Radium-F              ?            143 days          alpha
+...
+Lead                  207          ?                 no rays
+
+As soon as the transmutation theory of radio-activity was accepted, it
+became natural to speculate about the intimate structure of the radio-
+active atoms, and the mode in which they broke up with the liberation of
+some of their store of internal energy.  How could we imagine an atomic
+structure which would persist unchanged for long periods of time, and yet
+eventually spontaneously explode, as here an atom and there an atom reached
+a condition of instability?
+
+The atomic theory of corpuscles or electrons fortunately was ready to be
+applied to this new problem.  Of the resulting speculations the most
+detailed and suggestive is that of J.J. Thomson.  ("Phil. Mag." March,
+1904.)  Thomson regards the atom as composed of a number of mutually
+repelling negative corpuscles or electrons held together by some central
+attractive force which he represents by supposing them immersed in a
+uniform sphere of positive electricity.  Under the action of the two
+forces, the electrons space themselves in symmetrical patterns, which
+depend on the number of electrons.  Three place themselves at the corner of
+an equilateral triangle, four at those of a square, and five form a
+pentagon.  With six, however, the single ring becomes unstable, one
+corpuscle moves to the middle and five lie round it.  But if we imagine the
+system rapidly to rotate, the centrifugal force would enable the six
+corpuscles to remain in a single ring.  Thus internal kinetic energy would
+maintain a configuration which would become unstable as the energy drained
+away.  Now in a system of electrons, electromagnetic radiation would result
+in a loss of energy, and at one point of instability we might well have a
+sudden spontaneous redistribution of the constituents, taking place with an
+explosive violence, and accompanied by the ejection of a corpuscle as a
+beta-ray, or of a large fragment of the atom as an alpha-ray.
+
+The discovery of the new property of radio-activity in a small number of
+chemical elements led physicists to ask whether the property might not be
+found in other elements, though in a much less striking form.  Are ordinary
+materials slightly radio-active?  Does the feeble electric conductivity
+always observed in the air contained within the walls of an electroscope
+depend on ionizing radiations from the material of the walls themselves? 
+The question is very difficult, owing to the wide distribution of slight
+traces of radium.  Contact with radium emanation results in a deposit of
+the fatal radium-D, which in 40 years is but half removed.  Is the
+"natural" leak of a brass electroscope due to an intrinsic radio-activity
+of brass, or to traces of a radio-active impurity on its surface?  Long and
+laborious researches have succeeded in establishing the existence of slight
+intrinsic radio-activity in a few metals such as potassium, and have left
+the wider problem still unsolved.
+
+It should be noted, however, that, even if ordinary elements are not radio-
+active, they may still be undergoing spontaneous disintegration.  The
+detection of ray-less changes by Rutherford, when those changes are
+interposed between two radio-active transformations which can be followed,
+show that spontaneous transmutation is possible without measureable radio-
+activity.  And, indeed, any theory of disintegration, such as Thomson's
+corpuscular hypothesis, would suggest that atomic rearrangements are of
+much more general occurrence than would be apparent to one who could
+observe them only by the effect of the projectiles, which, in special
+cases, owing to some peculiarity of atomic configuration, happened to be
+shot out with the enormous velocity needed to ionize the surrounding gas. 
+No evidence for such ray-less changes in ordinary elements is yet known,
+perhaps none may ever be obtained; but the possibility should not be
+forgotten.
+
+In the strict sense of the word, the process of atomic disintegration
+revealed to us by the new science of radio-activity can hardly be called
+evolution.  In each case radio-active change involves the breaking up of a
+heavier, more complex atom into lighter and simpler fragments.  Are we to
+regard this process as characteristic of the tendencies in accord with
+which the universe has reached its present state, and is passing to its
+unknown future?  Or have we chanced upon an eddy in a backwater, opposed to
+the main stream of advance?  In the chaos from which the present universe
+developed, was matter composed of large highly complex atoms, which have
+formed the simpler elements by radio-active or ray-less disintegration?  Or
+did the primaeval substance consist of isolated electrons, which have
+slowly come together to form the elements, and yet have left here and there
+an anomaly such as that illustrated by the unstable family of uranium and
+radium, or by some such course are returning to their state of primaeval
+simplicity?
+
+
+INDEX.
+
+Abraxas grossulariata.
+
+Acquired characters, transmission of.
+
+Acraea johnstoni.
+
+Adaptation.
+
+Adloff.
+
+Adlumia cirrhosa.
+
+Agassiz, A.
+
+Agassiz, L.
+
+Alexander.
+
+Allen, C.A.
+
+Alternation of generations.
+
+Ameghino.
+
+Ammon, O., Works of.
+
+Ammonites, Descent of.
+
+Amphidesmus analis.
+
+Anaea divina.
+
+Andrews, C.W.
+
+Angiosperms, evolution of.
+
+Anglicus, Bartholomaeus.
+
+Ankyroderma.
+
+Anomma.
+
+Antedon rosacea.
+
+Antennularia antennina.
+
+Anthropops.
+
+Ants, modifications of.
+
+Arber, E.A.N.,
+--and J. Parkin, on the origin of Angiosperms.
+
+Archaeopteryx.
+
+Arctic regions, velocity of development of life in.
+
+Ardigo.
+
+Argelander.
+
+Argyll, Huxley and the Duke of.
+
+Aristotle.
+
+Arrhenius.
+
+Asterias, Loeb on hybridisation of.
+
+Autogamy.
+
+Avena fatua.
+
+Avenarius.
+
+Bacon, on mutability of species.
+
+Baehr, von, on Cytology.
+
+Baer, law of von.
+
+Bain.
+
+Baldwin, J.M.
+
+Balfour, A.J.
+
+Ball, J.
+
+Barber, Mrs M.E., on Papilio nireus.
+
+Barclay, W.
+
+Barratt.
+
+Bary, de.
+
+Bates, H.W., on Mimicry.
+--Letters from Darwin to.
+--elsewhere.
+
+Bateson, A.
+
+BATESON, W., on "Heredity and Variation in Modern lights".
+--on discontinuous evolution.
+--on hybridisation.
+
+Bateson, W. and R.P. Gregory.
+
+Bathmism.
+
+Beche, de la.
+
+Beck, P.
+
+Becquerel, H.
+
+Beebe, C.W., on the plumage of birds.
+--on sexual selection.
+
+Beguyer de Chancourtois.
+
+Bell's (Sir Charles) "Anatomy of Expression".
+
+Belopolsky.
+
+Belt, T., on Mimicry.
+
+Beneden, E. van.
+
+Benson, M.
+
+Bentham, G., on Darwin's species-theory.
+--on geographical distribution.
+
+Bentham, Jeremy.
+
+Bergson, H.
+
+Berkeley.
+
+Berthelot.
+
+Betham, Sir W.
+
+Bickford, E., experiments on degeneration by.
+
+Bignonia capreolata.
+
+Biophores.
+
+Birds, geological history of.
+
+Blanford, W.T.
+
+Blaringhem, on wounding.
+
+Blumenbach.
+
+Bodin.
+
+Boltwood, B.B.
+
+Bonald, on war.
+
+Bonnet.
+
+Bonney, T.G.
+
+Bonnier, G.
+
+Bopp, F., on language.
+
+BOUGLE C., on "Darwinism and Sociology".
+
+Bourdeau.
+
+Bourget, P.
+
+Boutroux.
+
+Boveri, T.
+
+Brachiopods, history of.
+
+Brassica, hybrids of.
+
+Brassica Napus.
+
+Broca.
+
+Brock, on Kant.
+
+Brown, Robert.
+
+Brugmann and Osthoff.
+
+Brugmann.
+
+Brunetiere.
+
+Bruno, on Evolution.
+
+Buch, von.
+
+Bucher, K.
+
+Buckland.
+
+Buckle.
+
+Buffon.
+
+Burchell, W.J.
+
+Burck, W.
+
+Burdon-Sanderson, J., letter from.
+
+BURY, J.B., on "Darwinism and History".
+
+Butler, A.G.
+
+Butler, Samuel.
+
+Butschli, O.
+
+Butterflies, mimicry in.
+--sexual characters in.
+
+Cabanis.
+
+Campbell.
+
+Camels, geological history of.
+
+Camerarius, R.J.
+
+Candolle, A. de.
+
+Cannon and Davenport, experiments on Daphniae by.
+
+Capsella bursapastoris.
+
+Carneri.
+
+Castnia linus.
+
+Catasetum barbatum.
+
+Catasetum tridentatum.
+
+Caterpillars, variation in.
+
+Celosia, variability of.
+
+Cereals, variability in.
+
+Cesnola, experiments on Mantis by.
+
+Chaerocampa, colouring of.
+
+Chambers, R., "The Vestiges of Creation" by.
+
+Chromosomes and Chromomeres.
+
+Chun.
+
+Cieslar, experiments by.
+
+Circumnutation, Darwin on.
+
+Claus.
+
+Cleistogamy.
+
+Clerke, Miss A.
+
+Clodd, E.
+
+Cluer.
+
+Clytus arietis.
+
+Coadaptation.
+
+Codrington.
+
+Cohen and Peter.
+
+Collingwood.
+
+Colobopsis truncata.
+
+Colour, E.B. Poulton on The Value in the Struggle for life of.
+--influence and temperature on changes in.
+--in relation to Sexual Selection.
+
+Colours, incidental.
+--warning.
+
+Comte, A.
+
+Condorcet.
+
+Cope.
+
+Coral reefs, Darwin's work on.
+
+Correlation of organisms, Darwin's idea of the.
+
+Correlation of parts.
+
+Corydalis claviculata.
+
+Cournot.
+
+Couteur, Col. Le.
+
+Crooks, Sir William.
+
+Cruger, on Orchids.
+
+Cunningham and Marchand, on the brain.
+
+Curie, M. and Mme.
+
+Cuvier.
+
+Cycadeoidea dacotensis.
+
+Cycads, geological history of.
+
+Cystidea, an ancient group.
+
+Cytology and heredity.
+
+Cytolysis and fertilisation.
+
+Czapek.
+
+Dalton's atomic theory.
+
+Dana, J.D., on marine faunas.
+
+Danaida chrysippus.
+
+Danaida genutia.
+
+Danaida plexippus.
+
+Dante.
+
+Dantec, Le,
+
+Darwin, Charles, as an Anthropologist.
+--on ants.
+--and the "Beagle" Voyage.
+--on the Biology of Flowers.
+--as a Botanist.
+--his influence on Botany.
+--and S. Butler.
+--at Cambridge.
+--on Cirripedia.
+--on climbing plants.
+--on colour.
+--on coral reefs.
+--on the Descent of Man.
+--his work on Drosera.
+--at Edinburgh.
+--his influence on Animal Embryology.
+--on Geographical Distribution.
+--his work on Earthworms.
+--evolutionist authors referred to in the "Origin" by.
+--and E. Forbes.
+--on the geological record.
+--and Geology.
+--his early love for geology.
+--his connection with the Geological Society of London.
+--and Haeckel.
+--and Henslow.
+--and History.
+--and Hooker.
+--and Huxley.
+--on ice-action.
+--on igneous rocks.
+--on Lamarck.
+--on Language.
+--his Scientific Library.
+--and the Linnean Society.
+--and Lyell.
+--and Malthus.
+--on Patrick Matthew.
+--on mental evolution.
+--on Mimicry.
+--a "Monistic Philosopher." 
+--on the movements of plants.
+--on Natural Selection.
+--a "Naturalist for Naturalists."
+--on Paley.
+
+Darwin, Charles, his Pangenesis hypothesis.
+--on the permanence of continents.
+--his personality.
+--his influence on Philosophy.
+--predecessors of.
+--his views on religion, etc.
+--his influence on religious thought.
+--his influence on the study of religions.
+--his methods of research.
+--and Sedgwick.
+--on Sexual Selection.
+--the first germ of his species theory.
+--on H. Spencer.
+--causes of his success.
+--on Variation.
+--on the "Vestiges of Creation".
+--on volcanic islands.
+--and Wallace.
+--letter to Wallace from.
+--letter to E.B. Wilson from.
+
+Darwin, E., on the colour of animals.
+--Charles Darwin's reference to.
+--on evolution.
+
+DARWIN, F., on "Darwin's work on the Movements of Plants".
+--on Darwin as a botanist.
+--observations on Earthworms by.
+--on Lamarckism.
+--on Memory.
+--on Prichard's "Anticipations".
+--various.
+
+DARWIN, SIR G., on "The Genesis of Double Stars".
+--on the earth's mass.
+
+Darwin, H.
+
+Darwin, W.
+
+Darwinism, Sociology, Evolution and.
+
+Davenport and Cannon, experiments on Daphniae by.
+
+David, T.E., his work on Funafuti.
+
+Death, cause of natural.
+
+Debey, on Cretaceous plants.
+
+Debierne.
+
+Degeneration.
+
+Delage, experiments on parthenogenesis by.
+
+Delbruck.
+
+Democritus.
+
+Deniker.
+
+Descartes.
+
+Descent, history of doctrine of.
+
+"Descent of Man", G. Schwalbe on "The".
+--Darwin on Sexual Selection in "The".
+--rejection in Germany of "The".
+
+Desmatippus.
+
+Desmoulins, A., on Geographical Distribution.
+
+Detto.
+
+Development, effect of environment on.
+
+Dianthus caryophyllus.
+
+Diderot.
+
+Digitalis purpurea.
+
+Dimorphism, seasonal.
+
+Dismorphia astynome.
+
+Dismorphia orise.
+
+Distribution, H. Gadow on Geographical.
+--Sir W. Thiselton-Dyer on.
+
+Dittrick, O.
+
+Dixey, F.A., on the scent of Butterflies.
+
+Dolichonyx oryzivorus.
+
+Dorfmeister.
+
+Down, Darwin at.
+
+Draba verna.
+
+Dragomirov.
+
+Driesch, experiments by.
+--elsewhere.
+
+Drosera, Darwin's work on.
+
+Dryopithecus.
+
+Dubois, E., on Pithecanthropus.
+
+Duhring.
+
+Duhamel.
+
+Duncan, J.S.
+
+Duncan, P.B.
+
+Duns Scotus.
+
+Duret, C.
+
+Durkheim, on division of labour.
+
+Dutrochet.
+
+Echinoderms, ancestry of.
+
+Ecology.
+
+Eimer.
+
+Ekstam.
+
+Elephants, geological history of.
+
+Elymnias phegea.
+
+E. undularis.
+
+Embleton, A.L.
+
+Embryology, A. Sedgwick on the influence of Darwin on.
+
+Embryology, as a clue to Phylogeny.
+--the Origin of Species and.
+
+Empedocles.
+
+Engles.
+
+Environment, action of.
+--Klebs on the influence on plants of.
+--Loeb on experimental study in relation to.
+
+Eohippus.
+
+Epicurus, a poet of Evolution.
+
+Eristalis.
+
+Ernst.
+
+Ernst, A., on the Flora of Krakatau.
+
+Eschscholzia californica.
+
+Espinas.
+
+Eudendrium racemosum.
+
+Evolution, in relation to Astronomy.
+--and creation.
+--conception of.
+--discontinuous.
+--experimental.
+--factors of.
+--fossil plants as evidence of.
+--and language.
+--of matter, W.C.D. Whetham on.
+--mental.
+--Lloyd Morgan on mental factors in.
+--Darwinism and Social.
+--Saltatory.
+--Herbert Spencer on.
+--Uniformitarian.
+--Philosophers and modern methods of studying.
+
+Expression of the Emotions.
+
+Fabricius, J.C., on geographical distribution.
+
+Farmer, J.B.
+
+Farrer, Lord.
+
+Fearnsides, W.G.
+
+Felton, S., on protective resemblance.
+
+Ferri.
+
+Ferrier, his work on the brain.
+
+Fertilisation, experimental work on animal-.
+
+Fertilisation of Flowers.
+
+Fichte.
+
+Field, Admiral A.M.
+
+Fischer, experiments on Butterflies by.
+
+Fitting.
+
+Flemming, W.
+
+Flourens.
+
+Flowering plants, ancestry of.
+
+Flowers, K. Goebel on the Biology of.
+
+Flowers and Insects.
+
+Flowers, relation of external influences to the production of.
+
+Fol, H.
+
+Forbes, E.
+--and C. Darwin.
+
+Ford, S.O. and A.C. Seward, on the Araucarieae.
+
+Fossil Animals, W.B. Scott on their bearing on evolution.
+
+Fossil Plants, D.H. Scott on their bearing on evolution.
+
+Fouillee.
+
+Fraipont, on skulls from Spy.
+
+FRAZER, J.G., on "Some Primitive Theories of the Origin of Man". 
+--various.
+
+Fruwirth.
+
+Fumaria officinalis.
+
+Funafuti, coral atoll of.
+
+Fundulus.
+
+F. heteroclitus.
+
+GADOW, H., on "Geographical Distribution of Animals".
+--elsewhere.
+
+Gartner, K.F.
+
+Gallus bankiva.
+
+Galton, F.
+
+Gamble, F.W. and F.W. Keeble.
+
+Gasca, La.
+
+Geddes, P.
+
+Geddes, P. and A.W. Thomson.
+
+Gegenbauer.
+
+Geikie, Sir A.
+
+Geitonogamy.
+
+Genetics.
+
+Geographical Distribution of Animals.
+--of Plants.
+--influence of "The Origin of Species" on.
+--Wallace's contribution to.
+
+Geography of former periods, reconstruction of.
+
+Geology, Darwin and.
+
+Geranium spinosum.
+
+Germ-plasm, continuity of.
+--Weismann on.
+
+Germinal Selection.
+
+Gibbon.
+
+Gilbert.
+
+GILES, P., on "Evolution and the Science of Language".
+
+Giuffrida-Ruggeri.
+
+Giotto.
+
+Gizycki.
+
+Glossopteris Flora.
+
+Gmelin.
+
+Godlewski, on hybridisation.
+
+GOEBEL, K., on "The Biology of Flowers".  
+--his work on Morphology.
+
+Goethe and Evolution. 
+--on the relation between Man and Mammals.
+--elsewhere.
+
+Goldfarb.
+
+Gondwana Land.
+
+Goodricke, J.
+
+Gore, Dr.
+
+Gorjanovic-Kramberger.
+
+Gosse, P.H.
+
+Grabau, A.W., on Fusus.
+
+Grand'Eury, F.C., on fossil plants.
+
+Grapta C. album.
+
+Gravitation, effect on life-phenomena of.
+
+Gray, Asa.
+
+Gregoire, V.
+
+Groom, T.T., on heliotropism.
+
+Groos.
+
+Grunbaum, on the brain.
+
+Guignard, L.
+
+Gulick.
+
+Guppy, on plant-distribution.
+
+Guyau.
+
+Gwynne-Vaughan, D.T., on Osmundaceae.
+
+Gymnadenia conopsea.
+
+Haberlandt, G.
+
+Haddon, A.C.
+
+HAECKEL, E., on "Charles Darwin as an Anthropologist".
+--on Colour.
+--and Darwin.
+--on the Descent of Man.
+--contributions to Evolution by.
+
+Haeckel, E., on Lamarck.
+--on Language.
+--a leader in the Darwinian controversy.
+--on Lyell's influence on Darwin.
+--various.
+
+Hacker.
+
+Hagedoorn, on hybridisation.
+
+Hales, S.
+
+Hansen.
+
+Harker, A.
+
+HARRISON, J.E., on "The Influence of Darwinism on the Study of Religions".
+
+Hartmann, von.
+
+Harvey.
+
+Haupt, P., on  Language.
+
+Haycraft.
+
+Hays, W.M.
+
+Hegel.
+
+Heliconius narcaea.
+
+Heliotropism in animals.
+
+Henslow, Rev. J.S. and Darwin.
+
+Hensen, Van.
+
+Herbst, his experiments on sea urchins.
+
+Heracleitus.
+
+Herder.
+
+Heredity and Cytology. 
+--Haeckel on.
+--and Variation.
+--various.
+
+Hering, E., on Memory.
+
+Herschel, J. 
+
+Hertwig, R. 
+
+Hertwig, O. 
+
+Hertz.
+
+Heteromorphosis.
+
+Heterostylism.
+
+Heuser, E. 
+
+Hewitt.
+
+Heyse's theory of language.
+
+Hinde, G.J., his work on Funafuti.
+
+Hipparion.
+
+Hippolyte cranchii.
+
+Hirase.
+
+History, Darwin and.
+
+Hobbes, T. 
+
+Hobhouse.
+
+HOFFDING, H., on "The Influence of the Conception of Evolution on Modern
+Philosophy".
+
+Hofmeister, W. 
+
+Holmes, S.J., on Arthropods.
+
+Holothurians, calcareous bodies in skin of.
+
+Homo heidelbergensis.
+
+Homo neandertalensis.
+
+Homo pampaeus.
+
+Homo primigenius.
+
+Homunculus.
+
+Hooker, Sir J.D., and Darwin.
+--on Distribution of Plants.
+--on Ferns.
+--Letter to the Editor from.
+
+Horner, L. 
+
+Horse, Geological history of the.
+
+Huber.
+
+Hubert and Mauss.
+
+Hubrecht, A.R.W.
+
+Hugel, F. von.
+
+Humboldt, A. von.
+
+Humboldt, W. von.
+
+Hume.
+
+Hutcheson.
+
+Hutton.
+
+Huxley, T.H., and Darwin.
+--and the Duke of Argyll.
+--on Embryology.
+--on Geographical Distribution.
+--on Lamarck.
+--Letter to J.W. Judd from.
+--on Lyell.
+--on Man.
+--on "The Origin of Species".
+--on Selection.
+--on Teleology.
+--on transmission of acquired characters.
+--various.
+
+Hybridisation.
+
+Hybrids, Sterility of.
+
+Hyracodon.
+
+Iberis umbellata.
+
+Ikeno.
+
+Imperfection of the Geological Record.
+
+Ingenhousz, on plant physiology.
+
+Inheritance of acquired characters.
+
+Insects and Flowers.
+
+Instinct.
+
+Instincts, experimental control of animal.
+
+Ipomaea purpurea.
+
+Irish Elk, an example of co-adaptation.
+
+Jacobian figures.
+
+Jacoby, "Studies in Selection" by.
+
+James, W. 
+
+Janczewski.
+
+Jeans, J.H.
+
+Jennings, H.S., on Paramoecium.
+
+Jentsch.
+
+Jespersen, Prof., Theory of.
+
+Johannsen, on Species.
+
+Jones, Sir William, on Language.
+
+Jordan.
+
+JUDD, J.W., on "Darwin and Geology".
+
+Kallima, protective colouring of.
+
+Kallima inachis.
+
+Kammerer's experiments on Salamanders.
+
+Kant, I. 
+
+Keane, on the Primates.
+
+Keeble, F.W. and F.W. Gamble, on Colour-change.
+
+Keith, on Anthropoid Apes.
+
+Kellogg, V., on heliotropism.
+
+Kepler.
+
+Kerguelen Island.
+
+Kidd.
+
+Kidston, R., on fossil plants.
+
+Killmann, on origin of human races.
+
+King, Sir George.
+
+Klaatsch, on Ancestry of Man.
+
+Klaatsch and Hauser.
+
+KLEBS, G., on "The influence of Environment on the forms of plants".
+
+Kniep.
+
+Knies.
+
+Knight, A., experiments on plants by.
+--on Geotropism.
+
+Knight-Darwin law.
+
+Knuth.
+
+Kolliker, his views on Evolution.
+
+Kolreuter, J.G.
+
+Kohl.
+
+Korschinsky.
+
+Kowalevsky, on fossil horses.
+
+Krakatau, Ernst on the Flora of.
+
+Krause, E. 
+
+Kreft, Dr.
+
+Kropotkin.
+
+Kupelwieser, on hybridisation.
+
+Lagopus hyperboreus.
+
+Lamarck, his division of the Animal Kingdom.
+--Darwin's opinion of.
+--on Evolution.
+--on Man.
+--various.
+
+Lamarckian principle.
+
+Lamb, C. 
+
+Lamettrie.
+
+Lamprecht.
+
+Lanessan, J.L. de.
+
+Lang.
+
+Lange.
+
+Language, Darwin on.
+--Evolution and the Science of.
+--various.
+
+Lankester, Sir E. Ray, on degeneration.
+--on educability.
+--on the germ-plasm theory.
+--elsewhere.
+
+Lapouge, Vacher de.
+
+Larmor, J. 
+
+Lartet, M.E.
+
+Lassalle.
+
+Lathyrus odoratus.
+
+Lavelaye, de.
+
+Lawrence, W. 
+
+Lehmann.
+
+Lehmann-Nitsche.
+
+Leibnitz.
+
+Lepidium Draba.
+
+Lepidoptera, variation in.
+
+Leskien, A., on language.
+
+Lessing.
+
+Leucippus.
+
+Levi, E. 
+
+Lewes, G.H.
+
+Lewin, Capt.
+
+Liapounoff.
+
+Liddon, H.P.
+
+Light, effect on organisms of.
+
+Limenitis archippus.
+--arthemis.
+
+Linnaeus.
+
+Livingstone, on plant-forms.
+
+Llamas, geological history of.
+
+Lockyer, Sir N. 
+
+Locy, W.A.
+
+LOEB, J., on "The Experimental Study of the influence of environment on
+Animals.
+
+Loew, E.
+
+Longstaff, G.B., on the Scents of Butterflies.
+
+Lorentz.
+
+Lotsy, J.P.
+
+Love, A.E.W.
+
+Lovejoy.
+
+Lubbock.
+
+Lucas, K.
+
+Lucretius, a poet of Evolution.
+
+Lumholtz, C.
+
+Luteva macrophthalma.
+
+Lycorea halia.
+
+Lyell, Sir Charles, and Darwin.
+--the influence of.
+--on geographical distribution.
+--on "The Origin of Species".
+--on the permanence of Ocean-basins.
+--publication of the "Principles" by.
+--the uniformitarian teaching of.
+
+Lythrum salicaria.
+
+Macacus, ear of.
+
+MacDougal, on wounding.
+
+Mach, E.
+
+Macromytis flexuosa, colour-change in.
+
+Magic and religion.
+
+Mahoudeau.
+
+Maillet, de.
+
+Majewski.
+
+Malthus, his influence on Darwin.
+--various.
+
+Mammalia, history of.
+
+Man, Descent of.
+--J.G. Frazer on some primitive theories of the origin of.
+--mental and moral qualities of animals and.
+--pre-Darwinian views on the Descent of.
+--religious views of primitive.
+--Tertiary flints worked by.
+
+"Man", G. Schwalbe on Darwin's "Descent of".
+
+Manouvrier.
+
+Mantis religiosa, colour experiments on.
+
+Marett, R.R.
+
+Markwick.
+
+Marshall, G.A.K.
+
+Marx.
+
+Massart.
+
+Masters, M.
+
+Matonia pectinata.
+
+Matthew, P., and Natural Selection.
+
+Maupertuis.
+
+Maurandia semperflorens.
+
+Mauss and Herbert.
+
+Mauthner.
+
+Maxwell.
+
+Maxwell, Clerk.
+
+Mayer, R. 
+
+Mechanitis lysimnia.
+
+Meehan, T.
+
+Meldola, R., Letters from Darwin to.
+
+Melinaea ethra.
+
+Mendel.
+
+Mendeleeff.
+
+Merrifield.
+
+Merz, J.T.
+
+Mesembryanthemum truncatum.
+
+Mesohippus.
+
+Mesopithecus.
+
+Metschnikoff.
+
+Mill, J.S.
+
+Mimicry.
+--H.W. Bates on.
+--F. Muller on.
+
+Mimulus luteus.
+
+Miquel, F.W.A.
+
+Mobius.
+
+Mohl, H. von.
+
+Moltke, on war.
+
+Monachanthus viridis.
+
+Monkeys, fossil.
+
+Montesquieu.
+
+Montgomery, T.H.
+
+Monstrosoties.
+
+Monticelli.
+
+Moore, J.E.S.
+
+MORGAN, C. LLOYD, on "Mental Factors in Evolution".
+--on Organic Selection.
+
+Morgan, T.H.
+
+Morse, E.S., on colour.
+
+Morselli.
+
+Mortillet.
+
+Moseley.
+
+Mottier, M.
+
+Muller, Fritz, "Fur Darwin" by.
+--on Mimicry.
+
+Muller, Fritz.
+
+Muller, J.
+
+Muller, Max, on language.
+
+Murray, A., on geographical distribution.
+
+Murray, G. 
+
+Mutability.
+
+Mutation.
+
+Myanthus barbatus.
+
+Myers, G.W., on Eclipses.
+
+Nageli.
+
+Nathorst, A.G.
+
+Nathusius.
+
+Natural Selection, and adaptation.
+--Darwin's views on.
+--Darwin and Wallace on.
+--and design.
+--and educability.
+--Fossil plants in relation to.
+--and human development.
+--and Mimicry.
+--and Mutability.
+--various.
+
+Naudin.
+
+Neandertal skulls.
+
+Nemec.
+
+Neoclytus curvatus.
+
+Neodarwinism.
+
+Neumayr, M.
+
+Newton, A.
+
+Newton, I.
+
+Niebuhr.
+
+Nietzsche.
+
+Nilsson, on cereals.
+
+Nitsche.
+
+Noire.
+
+Noll.
+
+Novicow.
+
+Nuclear division.
+
+Nussbaum, M.
+
+Nuttall, G.H.F.
+
+Occam.
+
+Odin.
+
+Oecology, see Ecology.
+
+Oenothera biennis.
+
+Oenothera gigas.
+
+Oenothera Lamarckiana.
+
+Oenothera muricata.
+
+Oenothera nanella.
+
+Oestergren, on Holothurians.
+
+Oken, L.
+
+Oliver, F.W., on Palaeozoic Seeds.
+
+Ononis minutissima.
+
+Ophyrs apifera.
+
+Orchids, Darwin's work on the fertilisation of.
+
+Organic Selection.
+
+"Origin of Species", first draft of the. 
+--geological chapter in the.
+
+Orthogenesis.
+
+Ortmann, A.E.
+
+Osborn, H.F.
+--"From the Greeks to Darwin" by.
+
+Osthoff and Brugmann.
+
+Ostwald, W. 
+
+Ovibos moschatus.
+
+Owen, Sir Richard.
+
+Oxford, Ashmolean Museum at.
+
+Packard, A.S.
+
+Palaeontological Record, D.H. Scott on the.
+--W.B. Scott on the.
+
+Palaeopithecus.
+
+Paley.
+
+Palitzch, G.
+
+Palm.
+
+Pangenesis.
+
+Panmixia, Weismann's principle of.
+
+Papilio dardanus.
+
+Papilio meriones.
+
+Papilio merope.
+
+Papilio nireus.
+
+Paramoecium, Jennings on.
+
+Parker, G.H., on Butterflies.
+
+Parkin, J. and E.A.N. Arber, on the origin of Angiosperms.
+
+Parthenogenesis, artificial.
+
+Paul, H. and Wundt.
+
+Pearson, K.
+
+Peckham, Dr and Mrs, on the Attidae.
+
+Penck.
+
+Penzig.
+
+Peripatus, distribution of.
+
+Peridineae.
+
+Permanence of continents.
+
+Perrier, E.
+
+Perrhybris pyrrha.
+
+Perthes, B. de.
+
+Peter, on sea urchin's eggs.
+
+Petunia violacea.
+
+Pfeffer, W.
+
+Pfitzner, W.
+
+Pflueger.
+
+Phillips.
+
+Philosophy, influence of the conception of evolution on modern.
+
+Phryniscus nigricans.
+
+Phylogeny, embryology as a clue to.
+--Palaeontological evidence on.
+
+Physiology of plants, development of.
+
+Piccard, on Geotropism.
+
+Pickering, spectroscopic observations by.
+
+Piranga erythromelas.
+
+Pisum sativum.
+
+Pithecanthropus.
+
+Pitheculites.
+
+Planema epaea.
+
+Plants, Darwin's work on the movements of.
+--geographical distribution of.
+--Palaeontological record of fossil.
+
+Platanthera bifolia.
+
+Plate.
+
+Plato.
+
+Playfair.
+
+Pliopithecus.
+
+Pocock, R.I.
+
+Poincare.
+
+Polarity, Vochting on.
+
+Polymorphic species.
+--variability in cereals.
+
+Polypodium incanum.
+
+Porthesia chrysorrhoea.
+
+Potonie, R.
+
+Pouchet, G.
+
+POULTON, E.B., on "The Value of Colour in the Struggle for Life".
+--experiments on Butterflies by.
+--on J.C. Prichard.
+--on Mimicry.
+--various.
+
+Pratt.
+
+Pratz, du.
+
+Premutation.
+
+Preuss, K. Th.
+
+Prichard, J.C.
+
+Primula, heterostylism in.
+
+Primula acaulis.
+
+Primula elatior.
+
+Primula officinalis.
+
+Promeces viridis.
+
+Pronuba yuccasella.
+
+Protective resemblance.
+
+Protocetus.
+
+Protohippus.
+
+Psychology.
+
+Pteridophytes, history of.
+
+Pteridospermeae.
+
+Pucheran.
+
+Pusey.
+
+Quatrefages, A. de.
+
+Quetelet, statistical investigations by.
+
+Rabl, C.
+
+Radio-activity.
+
+Radiolarians.
+
+Raimannia odorata.
+
+Ramsay, Sir W. and Soddy.
+
+Ranke.
+
+Rau, A.
+
+Ray, J.
+
+Reade, Mellard.
+
+Recapitulation, the theory of.
+
+Reduction.
+
+Regeneration.
+
+Reid, C.
+
+Reinke.
+
+Religion, Darwin's attitude towards.
+--Darwin's influence on the study of.
+--and Magic.
+
+Religious thought, Darwin's influence on.
+
+Renard, on Darwin's work on volcanic islands.
+
+Reproduction, effect of environment on.
+
+Reptiles, history of.
+
+Reversion.
+
+Rhinoceros, the history of the.
+
+Ridley, H.N.
+
+Riley, C.V.
+
+Ritchie.
+
+Ritual.
+
+Roberts, A.
+
+Robertson, T.B.
+
+Robinet.
+
+Rolfe, R.A.
+
+Rolph.
+
+Romanes, G.J.
+
+Rothert.
+
+Roux.
+
+Rozwadowski, von.
+
+Ruskin.
+
+Rutherford, E.
+
+Rutot.
+
+Sachs, J.
+
+St Hilaire, E.G. de.
+
+Salamandra atra.
+
+Salamandra maculosa.
+
+Saltatory Evolution, (see also Mutations).
+
+Sanders, experiments on Vanessa by.
+
+Saporta, on the Evolution of Angiosperms.
+
+Sargant, Ethel, on the Evolution of Angiosperms.
+
+Savigny.
+
+Scardafella inca.
+
+Scent, in relation to Sexual Selection.
+
+Scharff, R.F.
+
+Schelling.
+
+Schlegel.
+
+Schleicher, A., on language.
+
+Schleiden and Schwann, Cell-theory of.
+
+Schmarda, L.K., on geographical distribution.
+
+Schoetensack, on Homo heidelbergensis.
+
+Schreiner, K.E.
+
+Schubler, on cereals.
+
+Schultze, O., experiments on Frogs.
+
+Schur.
+
+Schutt.
+
+SCHWALBE, G., on "The Descent of Man".
+
+Sclater, P.L., on geographical distribution.
+
+SCOTT, D.H., on "The Palaeontological Record (Plants)".
+--elsewhere.
+
+SCOTT, W.B., on "The Palaeontological Record (Animals)".
+
+Scrope.
+
+Scyllaea.
+
+Sechehaye, C.A.
+
+SEDGWICK, A., on "The Influence of Darwin on Animal Embryology".
+
+Sedgwick, A., Darwin's Geological Expedition with.
+
+Seeck, O.
+
+Seed-plants, origin of.
+
+Segregation.
+
+Selection, artificial.
+--germinal.
+
+Selection, natural (see Natural Selection).
+--organic.
+--sexual.
+--social and natural.
+--various.
+
+Selenka.
+
+Semnopithecus.
+
+Semon, R.
+
+Semper.
+
+Senebier.
+
+Senecio vulgaris.
+
+Sergi.
+
+Seward, A.C.
+--and S.O. Ford.
+--and J. Gowan.
+
+Sex, recent investigations on.
+
+Sharpe, D.
+
+Sherrington, C.S.
+
+Shirreff, P.
+
+Shrewsbury, Darwin's recollections of.
+
+Sibbern.
+
+Sinapis alba.
+
+Smerinthus ocellata.
+
+Smerinthus populi.
+
+Smerinthus tiliae.
+
+Smith, A.
+
+Smith, W.
+
+Snyder.
+
+Sociology, Darwinism and. 
+--History and.
+
+Soddy.
+
+Sollas, W.J.
+
+Sorley, W.R.
+
+Species, Darwin's early work on transmutation of.
+--geographical distribution and origin of.
+--immutability of.
+--influence on environment on.
+--Lamarck on.
+--multiple origin of.
+--the nature of a.
+--polymorphic.
+--production by physico-chemical means of.
+--and varieties.
+--de Vries's work on.
+
+Spencer, H., on evolution. 
+--on Lyell's "Principles".
+--on the nature of the living cell.
+--on primitive man.
+--on the theory of Selection.
+--on Sociology.
+
+Spencer, H., on the transmission of acquired characters.
+--on Weismann.
+--various.
+
+Sphingidae, variation in.
+
+Spinoza.
+
+Sports.
+
+Sprengel, C.K.
+
+Stability, principle of.
+
+Stahl.
+
+Standfuss.
+
+Stars, evolution of double.
+
+Stellaria media.
+
+Stephen, L.
+
+Sterility in hybrids.
+
+Sterne, C.
+
+Stockard, his experiments on fish embryos.
+
+STRASBURBER, E., on "The Minute Structure of Cells in relation to
+Heredity".
+
+Strongylocentrotus franciscanus.
+
+Strongylocentrotus purpuratus.
+
+Struggle for existence.
+
+Strutt, R.J.
+
+Stuart, A.
+
+Sturdee, F.C.D.
+
+Sutterlin, L.
+
+Sully.
+
+Sutton, A.W.
+
+Sutton, W.S.
+
+Svalof, agricultural station of.
+
+Swainson, W.
+
+Synapta, calcareous bodies in skin of.
+
+S. lappa.
+
+Syrphus.
+
+Tarde, G.
+
+Teleology and adaptation.
+
+Tennant, F.R.
+
+Teratology.
+
+Tetraprothomo.
+
+THISELTON-DYER, SIR WILLIAM, on "Geographical distribution of Plants".
+--on Burchell.
+--on protective resemblance.
+--elsewhere.
+
+THOMSON, J.A., on "Darwin's Predecessors.
+--elsewhere.
+--and P. Geddes.
+
+Thomson, Sir J.J.
+
+Theology, Darwin and.
+
+Tiedemann, F.
+
+Tooke, Horne.
+
+Totemism.
+
+Treschow.
+
+Treviranus.
+
+Trifolium pratense quinquefolium.
+
+Trigonias.
+
+Trilobites, phylogeny of.
+
+Tschermack.
+
+Turgot.
+
+Turner, Sir W.
+
+Twins, artificial production of.
+
+Tylor.
+
+Tyndall, W.
+
+Tyrrell, G.
+
+Uhlenhuth, on blood reactions.
+
+Underhill, E.
+
+Use and disuse.
+
+Vanessa.
+
+Vanessa antiope.
+
+Vanessa levana.
+
+Vanessa polychloros.
+
+Vanessa urticae.
+
+Van 't Hoff.
+
+Varanus Salvator.
+
+Variability, Darwin's attention directed to.
+--W. Bateson on. 
+--and cultivation.
+--causes of.
+--polymorphic.
+
+Variation, continuous and discontinuous. 
+--Darwin's views as an evolutionist, and as a systematist, on.
+--definite and indefinite.
+--environment and.
+--and heredity.
+--as seen in the life-history of an organism.
+--minute.
+--mutability and.
+--in relation to species.
+--H. de Vries on.
+
+Varigny, H. de.    
+
+Varro, on language.
+
+Veronica chamaedrys.
+
+Verworn.
+
+"Vestiges of Creation", Darwin on "The".
+
+Vierkandt.
+
+Vilmorin, L. de.
+
+Virchow, his opposition to Darwin.
+
+Virchow, on the transmission of acquired characters.
+
+Vochting.
+
+Vogt, C.
+
+Voltaire.
+
+Volvox.
+
+VRIES, H. de, on "Variation"
+--the Mutation theory of.
+
+WAGGETT, REV. P.N., on "The Influence of Darwin upon religious thought".
+
+Wagner.
+
+Waldeyer, W.
+
+Wallace, A.R., on Malayan Butterflies.
+--on Colour.
+--and Darwin.
+--on the Descent of Man.
+--on distribution.
+--on Malthus.
+--on Natural Selection.
+--on the permanence of continents.
+--on social reforms.
+--on Sexual Selection.
+
+Waller, A.D.
+
+Walton.
+
+Watson, H.C.
+
+Watson, S.
+
+Watt, J., and Natural Selection.
+
+Watts, W.W.
+
+Wedgwood, L.
+
+Weir, J.J.
+
+WEISMANN, A., on "The Selection Theory".
+--on Amphimixis.
+
+Weismann, A., his germ-plasm theory.
+--on ontogeny.
+--and Prichard.
+--and Spencer.
+--on the transmission of acquired characters.
+--various.
+
+Wells, W.C., and Natural Selection.
+
+Weston, S., on language.
+
+WHETHAM, W.C.D., on "The Evolution of Matter".
+
+Whewell.
+
+White, G.
+
+Wichmann.
+
+Wieland, G.R., on fossil Cycads.
+
+Wiesner, on Darwin's work on plant movements.
+
+Williams, C.M.
+
+Williamson, W.C.
+
+Wilson, E.B., on cytology.
+--letter from Darwin to.
+
+Wolf.
+
+Wollaston's, T.V. "Variation of Species".
+
+Woltmann.
+
+Woolner.
+
+Wundt, on language.
+
+Xylina vetusta.
+
+Yucca, fertilisation of.
+
+Zeiller, R., on Fossil Plants.
+
+Zeller, E.
+
+Zimmermann, E.A.W.
+
+Zittel, on palaeontological research.
+
+"Zoonomia", Erasmus Darwin's.
+
+
+
+
+
+End of Project Gutenberg Etext Darwin and Modern Science, by A C Seward
+
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