Darwin's time was divided between the study of the great deposits of red mudthe Pampean formationwith 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 collectinga taste his friend had in common with himselfhe 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 muchin 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 landthe 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 specimensthe 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 appearedthat 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 extinctionnot by overwhelming catastrophes； but by the silent and almost unobserved action of natural causes。 This leads him