darwin and modern science-第32章
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atural 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
