Discourses biological and geological : essays / by Thomas H. Huxley.

  • Thomas Henry Huxley
Date:
1894
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Licence: Public Domain Mark

Credit: Discourses biological and geological : essays / by Thomas H. Huxley. Source: Wellcome Collection.

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    from a very remote ejooch of geological time, the earth has been peopled by a continual succession of the higher forms of animals and plants, these either must have been created, or they have arisen by evolution. And in respect of certain groups of animals, the well-established facts of paleontology leave no rational doubt that they arose by the latter method. In the second place, there are no data what- ever, which justify the biologist in assigning any, even approximately definite, period of time, either long or short, to the evolution of one species from another by the process of variation and selection. In the ninth of the following essays, I have taken pains to prove that the change of animals has gone on at very different rates in different groups of living beings; that some types have persisted with little change from the paleo- zoic epoch till now, while others have changed rapidly within the limits of an epoch. In 1862 (see below p. 803, 304) in 1863 (vol. II., p. 461) and again in 1864 {ibid., p. 89—91) I argued, not as a matter of speculation, but, from paleonto- logical facts, the bearing of which I beheve, up to that time, had not been shown, that any ade- quate hypothesis of the causes of evolution must be consistent with progression, stationariness and retrogression, of the same type at different epochs; of different types in the same epoch; and that Darwin's hypothesis fulfilled these conditions.
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