The Principles of Biology, Volumen1D. Appleton, 1866 |
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Términos y frases comunes
acid Acrogens actions adaptation aggregate altered Amphibia animals arise arrangement assimilation atoms become binary compounds body carbonic carbonic acid cause cells changes chemical colloids combination complex compounds conception constituting continuous contrasts correspondence creatures crustaceans crystalloids Darwin definite degree differentiation direct displayed distinct divergence effects embryo environment equilibration ethereal waves evidence exhibit exist external facts fertilized germ functions further gamogenesis genesis greater groups growth habitats habitually heat Hence heterogeneity higher Hydrozoa hypothesis of evolution implies incident forces increase individuals Infusoria inorganic kind less living mammals manifest mass ment modes modifications molecular mobility motion moving equilibrium multiplication muscles natural selection nitrogenous nutriment nutrition offspring organic matter oviparous ovum oxygen parent parthenogenesis peculiarity phenomena physiological units plants produced Protozoa races re-actions re-distribution relations result similarly special creations species stamens structure substances successive temperature tion tissues truth types undergo unlike variations vertebral Vertebrata vital
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Página 74 - is a definite combination of heterogeneous changes, both simultaneous and successive, in correspondence with external coexistences and sequences.
Página 242 - That most skilful breeder, Sir John Sebright, used to say, with respect to pigeons, that "he would produce any given feather in three years, but it would take him six years to obtain head and beak.
Página 492 - Their implications are no more materialistic than they are spiritualistic; and no more spiritualistic than they are materialistic.
Página 183 - There seems no alternative but to suppose that the chemical units combine into units immensely more complex than themselves, complex as they are; and that in each organism, the physiological -units produced by this further compounding of highly compound atoms, have a more or less distinctive character. We must conclude that in each case, some slight difference of composition . in these units, leading to some slight difference in their mutual play of forces, produces a difference in the form which...
Página 175 - It is a corollary from that primordial truth which, as we have seen, underlies all other truths, that whatever amount of power an organism expends in any shape is the correlate and equivalent of a power that was taken into it from without.
Página 61 - Life is a series of definite and successive changes, both of structure and composition, which take place within an individual without destroying its identity.
Página 247 - Kentucky, are blind. In some of the crabs the foot-stalk for the eye remains, though the eye is gone ; — the stand for the telescope is there, though the telescope with its glasses has been lost. As it is difficult to imagine that eyes, though useless, could be in any way injurious to animals living in darkness, their loss may be attributed to disuse.
Página 370 - Some of the cases of rudimentary organs are extremely curious; for instance, the presence of teeth in foetal whales, which when grown up have not a tooth in their heads; and the presence of teeth, which never cut through the gums, in the upper jaws of our unborn calves.
Página 445 - This survival of the fittest which I have here sought to express in mechanical terms, is that which Mr. Darwin has called " natural selection, or the preservation of favoured races in the struggle for life.
Página 400 - This wonderful relationship in the same continent between the dead and the living, will, I do not doubt, hereafter throw more light on the appearance of organic beings on our earth and their disappearance from it than any other class of facts.