Chapters on EvolutionChatto & Windus, 1883 - 383 páginas |
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Términos y frases comunes
adult air-bladder animal or plant animal world animalcule animals and plants appear appendages Axolotl barnacle become biological bird body bone buds Campodea cells changes chapter chiton cilia colonial common Compsognathus connected constitution crabs Crinoid cross-fertilisation crustaceans curious Darwin degeneration descent discover evidence evolution evolutionist exhibit existence fact favour fertilisation firstly fish flowers fossil frog geological germ gills higher animals idea illustrated individual insects jaws lampshells lancelet larva larvæ latter life-history likewise limbs living lobster marsupials ment metamorphosis missing links modification molluscs named natural selection naturalist Nauplius neighbours organs origin parent Penæus phases pistil pollen pollen-grains possess present primitive primrose produced protoplasm pteropod quadrupeds race regarded remarks represented reptiles resemblance rudimentary Sacculina scientific sea-squirt seen skull species sponge stage stamens Starfishes structure tail theory tion to-day variation varied vertebrate whilst wings worm young zoophyte
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Página 141 - that of the adult." Or, again, " embryology (or development) rises greatly in interest when we look at the embryo as a picture, more or less obscured, of the progenitor, either in its adult or larval state, of all the members of the same great class." Second to none in interest, in the eyes of
Página 95 - their not being blended together by innumerable transitional links, is a very obvious difficulty;" and again, "Why is not- all nature in confusion, instead of the species being,, as. we see them, well defined?" Alike grave, then, to evolutionists and their opponents is the question of
Página 1 - struck with certain facts in the distribution of the organic beings inhabiting South America, and in the geological relations of the present to the past inhabitants of that continent.
Página 294 - even to an earthworm, to be highly organised ? If it were no advantage, these forms would be left, by natural selection, unimproved or but little improved, and might remain for ages in their present lowly condition. And geology tells us that some of the lowest forms, as the foraminifera (Fig.
Página 317 - for believing that most of our great formations, rich in fossils, were deposited during periods of subsidence ; and that blank intervals of vast duration, as far as fossils are concerned, occurred during the periods when the bed of the sea was either stationary or rising, and likewise when sediment was not thrown down quickly enough to
Página 141 - race and species in time past. So that, once again to quote Darwin's words, " we can understand how it is that, in the eyes of most naturalists, the structure of. the embryo is even more important for classification
Página 140 - arches is as reasonably detailed, when Darwin states that, "in order to understand the existence of rudimentary organs, we have only to suppose that a former progenitor possessed the parts in question in a perfect state, and that under
Página 2 - by minute steps in various directions, but always checked and balanced by the necessary conditions, subject to which alone existence can be preserved, may, it is believed, be followed out so as to agree with all the phenomena presented by organised beings, their extinction and succession in past ages, and all the extraordinary modifications of form, instinct, and habits which they exhibit.
Página 317 - and preserve organic remains. During these long and blank intervals I suppose that the inhabitants of each region underwent a considerable amount of modification and extinction, and that there was much migration from other parts of the world. As we have reason to believe,
Página 286 - of nature that no organic being fertilises itself for a perpetuity of generations; but that a cross with another individual is occasionally —perhaps at long intervals of time—indispensable." Remarking the strange feature of the stamens and pistil of most flowers being placed closed together," as if for the very purpose of self-fertilisation," and yet being " mutually useless to each other,