Search Results - The Complete Work of Charles Darwin Online

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

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 [page] 138 THE VALUE OF COLOU

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

of but a single one. When, as in North America, a recent invader becomes the model determining the direction of evolution in some constituent of the ancient butterfly fauna, the case becomes especially striking. The effects produced on the mimic are generally sharper and more distinct than those seen in the concealing resemblances to bark, lichen, earth, c.,— the difference corresponding to the more definite and individual appearance usually presented by the pattern of the model as compared with

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

appearance of the former. The history thus unravelled may often be further confirmed by a study of the non-mimetic males of mimetic females. Many naturalists at the present day incline to return to the old belief that the history of evolution has been' discontinuous', proceeding by 'mutations' or large and definite steps of change. The comprehensive and detailed study of Mimicry as a piece of biological history certainly provides [page] 148 MIMICRY IN N. AMERICAN BUTTERFLIE

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

certain. Nevertheless the evidence at present available yields much support to the theory of Natural Selection as the motive cause of evolution. The facts certainly do not point to any other interpretation. They negative the conclusion that mimetic resemblances have been produced by the direct action of external forces (Hypothesis of External Causes) or by variation unguided by selection (Hypothesis of Internal Causes). Nor do they support Fritz Müller's earlier and daring speculation (see pp. 127-8

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

: Whence came the Danaini of North America? The answer requires a somewhat careful comparison between the New and Old World butterflies of this group. Among the commonest of the Old World Danaini, are certain species with tawny colouring, a black border, and black white-barred apex to the fore wing. The under surface is even more 1 Verhandl. d. V. Internal. Zool. Congr. z. Berlin, 1901, Jena, 1902, 171. See also Essays on Evolution (1908), 274: also errata. [page] 156 MIMICRY IN N. AMERICAN

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

through a crowded area without producing any effect on any member of the Lepidopterous fauna, or without themselves being affected thereby.'1 Abundant wide-ranging Danaines in the Old World, even when much smaller and with a less marked appearance, invariably produce some effect, and often themselves exhibit Müllerian resemblances. THE EVOLUTION OF LIMENITIS (BASILARCHIA) ARCHIPPUS AS A MIMIC OF THE INVADING DANAIDA PLEXIPPUS It has already been mentioned that a single species, undergoing

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

between such specimens and those from Florida, and also to ascertain the proportion which they bear to typical archippus. By far the most important feature in the evolution of floridensis is the general darkening of the ground-colour, and the material for such a transformation certainly exists freely in archippus, for the shade of brown varies immensely and may often be seen of as dark a tint as in floridensis, but not in my experience of precisely the same shade. [page] 171 INVESTIGATIONS

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

that later, after the separation had become complete, it spread northward over the whole range of its parent. The evolution of astyanax from arthemis was far simpler than that of archippus. The great difference in appearance between parent and offspring is brought about, as regards the upper surface, by the disappearance of the broad white band of arthemis together with all but a trace of the sub-apical white markings of the fore wings. Over and within the area formerly occupied by the white

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

a set of dark female forms well known in Argynnis, forms which he believes to be ancestral.1 It is probable that' the recent evolution of L. astyanax provided this ancestral form with a model which it could approach by small and easy steps of variation'.2 THE BEARING UPON THEORIES OF MIMICRY OF PHARM. PHILENOR AND ITS MIMICS Haase, who always shows an imperfect appreciation of the scopo of Fritz Müller's principle, apparently regarded all the species mentioned in the preceding section as simple

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

profound significance still, for the comprehension of the method of evolution, is the vast performance of Nature herself.1 Because of the bright promise it holds for the understanding of Nature's experiments, I have brought before you the subject of Mimicry in North American butterflies. In the introductory words I spoke of the relationship of my subject to the teachings of Darwin, and now I am anxious to connect this address by a closer link to the personality of the illustrious naturalist. With

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

conclusion that the Mimicry is in an incipient stage and that it has been reached and is probably still advancing by minute increments,—that the evolution is 'continuous'tothe last degree. 32. In addition to their bearing upon the problems of Mimicry, the examples considered 1 In the southernmost part of the range of bredowi, in Guatemala, the resemblance to Adelpha was very slightly augmented in the only two specimens from this locality I have had the opportunity of studying (Trans. Ent. Soc. Lond

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A331 Book: Poulton, Edward Bagnall. 1909. Charles Darwin and the Origin of species: addresses, etc., in America and England in the year of the two anniversaries. London: Longmans, Green, and Co. Text Image

endangered by the one man who held the same belief on much stronger grounds. We find the great geologist, at a later stage, ready to give up his belief if he can thereby obtain a weapon against evolution; and observe, in Darwin's answer to him and to the Duke of Argyll, an entire grasp of the problem conspicuously wanting in those authorities who expressed, at a—later date, an ill-founded enthusiasm for the worthless hypothesis of multiple Origins. [page] 25

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A36 Periodical contribution: Darwin Centenary Number. Christ's College Magazine. vol. XXIII, Easter Term, 1909. Text Image PDF

world in the Beagle. Is there any one now in College of whom a freshman of 1908 9 will write in a like strain, sixty years hence? JOHN PEILE. DARWIN AND THE LINNEAN SOCIETY. AT a special meeting of the Linnean Society of London held on the 1st of July, 1908, to celebrate the fiftieth anniversary of the reading of the joint papers on evolution by Charles Robert Darwin and Alfred Russel Wallace, the following striking words were spoken by Mr Francis Darwin: I wish to say a few words in my private

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A36 Periodical contribution: Darwin Centenary Number. Christ's College Magazine. vol. XXIII, Easter Term, 1909. Text Image PDF

about that organic diversity which has found such endless expression. But however this may be, it will ever stand to Darwin's credit that he did more than any other man to extend to the field of biology that great unifying principle of evolution, the recognition of which made it possible for an English bishop to write, All that lives, lives with one life. If we know that we share in this, we can wait for the revelation of its action. F. H. A. MARSHALL. [page] 24

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McGill-CA-OSLER0-P110[.166] Note: [1909] 4pp list of items to display at Darwin exhibition, Christ's College, Cambridge Text Image

The Complete Work of Charles Darwin Online 1 (✓ = sent now June 4) s ✓ 1 MSS First sketch of Origin of Species 1842 2 Second Sketch ─ 1844 s ✓ 3 s ✓ Note Book – a 'Beagle voyage 4 books ✓ s ✓ b Books to be Read 2 s ✓ - c Earliest Notes on Evolution B 1837 (1) s ✓ 4 Notes on Paley's Evidence s ✓ 5 ✓ Notes on Geology 2 envelopes s ✓ 6 ✓ Page of Expression of the Emotions 7 Zoological Note Book 1837? s ✓ 8 ✓ Diary- to 1881 s ✓ 9 Lecture tickets – Edinburgh University 2 lots ✓ s ✓ 10 Calling over

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A162 Book: Seward, A. C. ed. 1909. 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. Cambridge: Cambridge University Press. Text Image PDF

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

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A162 Book: Seward, A. C. ed. 1909. 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. Cambridge: Cambridge University Press. Text Image PDF

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

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A162 Book: Seward, A. C. ed. 1909. 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. Cambridge: Cambridge University Press. Text Image PDF

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 species1. 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

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A162 Book: Seward, A. C. ed. 1909. 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. Cambridge: Cambridge University Press. Text Image PDF

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

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A162 Book: Seward, A. C. ed. 1909. 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. Cambridge: Cambridge University Press. Text Image PDF

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