Palaeontology Or a Systematic Summary of Extinct Animals and Their Geological Relations

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Black, 1861 - 463페이지
 

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440 페이지 - But analogy may be a deceitful guide. Nevertheless all living things have much in common, . . . Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form into which life was first breathed."1...
446 페이지 - Organic remains, traced from their earliest known graves, are succeeded, one series by another, to the present period, and never re-appear when once lost sight of in the ascending search. As well might we expect a living Ichthyosaur in the Pacific, as a fossil whale in the Lias : the rule governs as strongly in the retrospect as the prospect. And not only as respects the Vertebrata, but the sum of the animal species at each successive geological period has been distinct and peculiar to such period.
448 페이지 - ... what, I say, have they differed from the artificial instruments which we ourselves plan with foresight and calculation for analogous uses, save in their greater complexity, in their perfection, and in the unity and simplicity of the elements which are modified to constitute these several locomotive organs. Everywhere in organic nature we see the means not only subservient to an end, but that end accomplished by the simplest means.
446 페이지 - Vertebrata, but the sum of the animal species at each successive geological period has been distinct and peculiar to such period. Not that the extinction of such forms or species was sudden or simultaneous : the evidences so interpreted have been but local : over the wider field of life at any given epoch, the change has been gradual; and, as it would, seem, obedient to some general, but as yet, ill-comprehended law. In regard to animal life, and its assigned work on this planet, there has, however,...
444 페이지 - Cetacea have existed, the evidence in the shape of bones and teeth, which latter enduring characteristics in most of the species are peculiar for their great number in the same individual, must have been abundantly deposited at the bottom of the sea ; and as cachalots, grampuses, dolphins, and porpoises...
435 페이지 - ... of any gradual diminution of the size of such species, but is the result of circumstances, which may be illustrated by the fable of the ' Oak and the Reed ; ' the smaller and feebler animals have bent and accommodated themselves to changes which have destroyed the larger species.
439 페이지 - ... and human objects, was agglutinated to the roof by the infiltration of water holding lime in solution ; that subsequently, and within the human period, such a great amount of change took place in the physical configuration of the district as to have caused the cave to be washed out and emptied of its contents, excepting the floor breccia, and the patches of material cemented to the roof and since coated with additional stalagmite.
435 페이지 - ... the species. If a dry season be gradually prolonged, the large mammal will suffer from the drought sooner than the small one ; if such alteration of climate affect the quantity of vegetable food, the bulky Herbivore will first feel the effects of stinted nourishment ; if new enemies...
434 페이지 - ... of the year when food was scarcest; they would also rear more young, which would tend to inherit these slight peculiarities. The less fleet ones would be rigidly destroyed. I can see no more reason to doubt that these causes in a thousand generations would produce a marked effect, and adapt the form of the fox or dog to the catching of hares instead of rabbits, than that greyhounds can be improved by selection and careful breeding.
434 페이지 - ... has to maintain against the surrounding agencies that are ever tending to dissolve the vital bond and subjugate the living matter to the ordinary chemical and physical forces.

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