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fluencesespecially of climate and foodwere 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 knownif it has known itof 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 leapsinduced 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 Buffonianmaintaining that environment moulded organisms adaptively； and in part a Goethianbelieving 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；