Search Results - The Complete Work of Charles Darwin Online

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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

. Anyone who is interested in the matter will find a full and exact statement of the case in as far as we know it, in Poulton's Essays on Evolution (pp. 373-3751). I need only add that three different mimetic female forms have been reared from the eggs of a single female in South Africa. The resemblance of these forms to their immune models goes so far that even the details of the local forms of the models are copied by the mimetic species. It remains to be said that in Madagascar a butterfly

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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

animal, the disappearance of the ear-muscles and the auditory passages, the displacement of the external nares to the forehead for the greater security of the breathing-hole during the brief appearance at the surface, and certain remarkable changes in the respiratory and circulatory organs which enable the animal to remain for a long time 1 The Evolution Theory, London, 1904, p. 144. [page] 6

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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

first arise through selection in the course of the evolution of the birds, for it formed the covering of the scales of their reptilian ancestors. It is quite true that a similar substance covered the scales of the Reptiles, but why should it not have arisen among them through selection? Or in what other way could it have arisen, since scales are also passively useful parts? It is true that if we are only to call adaptation what has been acquired by the species we happen to be considering, there

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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

modifications. These have been of paramount importance on many lines of evolution of the animal as well as of the vegetable kingdom. It is often assumed that monocotyledons are descended from some lower group of dicotyledons, probably allied to that which includes the buttercup family. On this view the monocotyledons must be assumed to have lost the cambium and all its influence on secondary growth, the differentiation of the flower into calyx and corolla, the second cotyledon or seed-leaf and

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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

such views had been promulgated; and many must, as Huxley says, have taken up his own position of critical expectancy1. 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, but it was true as far as it went. Evolution could thus in great measure be fairly represented as a consequence of demonstrable processes

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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

subjects which their teachers were investigating. During this period nevertheless one distinct advance was made, that with which Weismann's name is prominently connected. In Darwin's genetic scheme the hereditary transmission of parental experience and its consequences played a considerable role. Exactly how great that role was supposed to be, he with his habitual caution refrained from specifying, for the sufficient reason that he did not know. Nevertheless much of the process of Evolution

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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 temperature of our atmosphere decides that no liquid carbon shall be found on the face of the earth: but we do not suppose that the form of the diamond has been gradually achieved by a process of Selection. So again, as the course of descent branches in the successive generations, Selection determines along which branch Evolution shall proceed, but it does not decide what novelties that branch shall bring forth. La Nature contient le fonds de toutes ces vari t s, mais le hazard ou l'art les

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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

plane back, and so looked rather less prominent. The abundance of Adaptation, we all grant, is an immense, almost an unsurpassable difficulty in all non-Lamarckian views of Evolution; but if the steps by which that adaptation arose were fortuitous, to imagine them insensible is assuredly no help. In one most important respect indeed, as has often been observed, it is a multiplication of troubles. For the smaller the steps, the less could Natural Selection act upon them. Definite variations—and of

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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

chapter may be very briefly summarised. In it Darwin shows that the intellectual and moral faculties are perfected through natural selection. He inquires how it can come about that a tribe at a low level of evolution attains to a higher, although the best and bravest among them often pay for their fidelity and courage with their lives without leaving any descendants. In this case it is the sentiment of glory, praise and blame, the admiration of others, which bring about the increase of the better

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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

discovery, which he illustrated by a humorous sketch1. But there are still many followers in Darwin's footsteps in England. Keane has worked at the special genealogical tree of the Primates; Keith has inquired which of the anthropoid apes has the greatest number of characters in common with man; Morris concerns himself with the evolution of man in general, especially with his acquisition of the erect position. The recent discoveries of Pithecanthropus and Homo primigenius are being vigorously discussed

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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

indicate a common descent, and cannot be explained as phenomena of convergence. I believe I have shown in the above sketch that a theory which derives man directly from lower forms without regarding apes as transition-types leads ad absurdum. The close structural relationship between man and monkeys can only be understood if both are brought into the same line of evolution. To trace man's line of descent directly back to the old Eocene mammals, alongside of, but with no relation to these very

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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

cenogenesis. As early as 1874 I had emphasised, in the first chapter of my Evolution of Man, the importance of discriminating carefully between these two sets of phenomena: In the evolutionary appreciation of the facts of embryology we must take particular care to distinguish sharply and clearly between the primary, palingenetic evolutionary processes and the secondary, cenogenetic processes. The palingenetic phenomena, or embryonic recapitulations, are due to heredity, to the transmission of

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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

existed long before Darwinian evolution was thought of and will endure without any reference to philosophic speculations. She is a mistress in whose face are beauties and in whose arms are delights elsewhere unattainable. She is and always has been pursued for her own sake without any reference to philosophy, science, or utility. Darwin's own views of the bearing of the facts of embryology upon questions of wide scientific interest are perfectly clear. He writes1: On the other hand it is highly

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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

they ever discharged a branchial function. Until such evidence is forthcoming, it is beside the point to say that it cannot be disputed that they are evidence of a piscine ancestry. It must, therefore, be admitted that one outcome of the progress of embryological and palaeontological research for the last 50 years 1 The Evolution Theory, by A. Weismann, English Translation, Vol. II. p. 176, London, 1904. [page] 17

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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

Fayoum show us that the region sought for is Africa, and that the elephants form just such a series of gradual modifications as we have found among other hoofed animals. The 1 C. W. Andrews, On the Evolution of the Proboscidea, Phil. Trans. Roy. Soc. London, Vol. 196, 1904, p. 99. [page] 19

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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

lines of inquiry has established the theory of evolution upon a foundation of ever growing solidity. It is Darwin's imperishable glory that he prescribed the lines along which all the biological sciences were to advance to conquests not dreamed of when he wrote. [page 200

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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

governed by Natural Selection, just as much as the specialisation of the rostellum in an Orchid, or of the pappus in a Composite. Did space allow, other examples might be added. We may venture to maintain that the glimpses which the fossil record allows us into early stages in the evolution of organs now of high systematic importance, by no means justify the belief in any essential distinction between morphological and adaptive characters. Another point, closely connected with Darwin's theory

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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

accordance with the environment. In the examples mentioned the modified character in the simple varieties (or a number of characters in elementary species) appears more or less suddenly and is constant in the above sense. The result is what de Vries has 1 Bateson, Reports to the Evolution Committee of the Royal Society, London, 1902; cf. also Lotsy, Vorlesungen, Vol. I. p. 234. D. 16 [page] 24

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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

produced. But perhaps the view here put forward in regard to the production of form throws new light on this puzzling problem. 1 Mutationstheorie, Vol. I. pp. 412 et seq. 2 Korschinsky, Heterogenesis und Evolution, Flora, 1901. 3 L. de Vilmorin, Notices sur l'am lioration des plantes, Paris, 1886, p. 36. 4 Klebs, K nstliche Metamorphosen, Stuttgart, 1906, p. 152. [page] 24

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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

successive generations of the same species in these regions than in the temperate or tropical regions. The writer is inclined to believe that these results have some bearing upon a problem which plays an important role in theories of evolution, namely, the cause of natural death. It has been stated that the processes of differentiation and development lead also to the natural death of the individual. If we express this in chemical terms it means that the chemical processes which underlie development