n 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 chapterin which he compares the record of the rocks to the much mutilated volumes of a human historyremains 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 lifewe 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 remarkableI 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 〃Consisten