Evolution and AdaptationMacmillan, 1903 - Всего страниц: 470 |
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Стр. vii
... living things . The ques- tion at once suggests itself : How has such a relation been brought about ? Is it due to something inherent in the liv- ing matter itself , or is it something that has been , as it were , superimposed upon it ...
... living things . The ques- tion at once suggests itself : How has such a relation been brought about ? Is it due to something inherent in the liv- ing matter itself , or is it something that has been , as it were , superimposed upon it ...
Стр. viii
... living things is frowned upon , but I have failed to observe that the critics themselves refrain entirely from theorizing . They shut one door only to open another , which also leads out into the dark . To deny the right to speculative ...
... living things is frowned upon , but I have failed to observe that the critics themselves refrain entirely from theorizing . They shut one door only to open another , which also leads out into the dark . To deny the right to speculative ...
Стр. ix
... living things must be adapted more or less well to their environ- ment in order to remain in existence may , after all , account for the widespread occurrence of adaptation in animals and plants . It is this point of view that will be ...
... living things must be adapted more or less well to their environ- ment in order to remain in existence may , after all , account for the widespread occurrence of adaptation in animals and plants . It is this point of view that will be ...
Стр. 1
... living or lifeless ; but in the living organism this relation is a peculiar one ; first , because the plant or the animal is so constructed that it is suited to a particular set of physical conditions , and , second , because it may so ...
... living or lifeless ; but in the living organism this relation is a peculiar one ; first , because the plant or the animal is so constructed that it is suited to a particular set of physical conditions , and , second , because it may so ...
Стр. 6
... living amongst green foliage , where their color must make them conspicuous , rather than the reverse . The polar bear is the only member of the family that is white , and while this can scarcely be said to protect it from enemies ...
... living amongst green foliage , where their color must make them conspicuous , rather than the reverse . The polar bear is the only member of the family that is white , and while this can scarcely be said to protect it from enemies ...
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Часто встречающиеся слова и выражения
acquired characters adaptation adult advantage amongst ancestors animals and plants aphids appear arisen artificial selection assume become believe birds breed caterpillars causes cells color connection crustaceans Darwin Darwinian degeneration degrees descendants direction Draba verna eggs elementary species embryo environment evidence evolution exist experiments explain fact females fertilized flowers fluctuating variations gemmules geotropic germ-cells give heliotropic hybrid hypothesis important individuals inheritance of acquired insects instance instinct kind Lamarck Lamarckian large number larvæ later less light living long-styled males mammals ment moths mutation theory Nägeli natural selection occur offspring organs origin ornaments outcome pangenesis parent form parthenogenetic pistil polar body pollen present probable produced question race regard relation reproduction resemblance response result rotifers secondary sexual characters seeds sexual selection short-styled shown side sort spermatozoon stages stamens structure supposed takes place tion tropisms variability varieties Vries Weismann wings young
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Стр. 131 - To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree.
Стр. 116 - Can the principle of selection, which we have seen is so potent in the hands of man, apply under nature? I think we shall see that it can act most efficiently. Let the endless number of slight variations and individual differences occurring in our domestic productions, and, in a lesser degree, in those under nature, be borne in mind ; as well as the strength of the hereditary tendency.
Стр. 113 - The amount of food for each species of course gives the extreme limit to which each can increase ; but very frequently it is not the obtaining food, but the serving as prey to other animals, which determines the average numbers of a species.
Стр. 119 - ... be, compared with those accumulated by nature during whole geological periods. Can we wonder, then, that nature's productions should be far "truer" in character than man's productions; that they should be infinitely better adapted to the most complex conditions of life, and should plainly...
Стр. 167 - This form of selection depends, not on a struggle for existence in relation to other organic beings or to external conditions, but on a struggle between the individuals of one sex, generally the males, for the possession of the other «ex. The result is not death to the unsuccessful competitor, but few or no offspring.
Стр. 129 - LONG before the reader has arrived at this part of my work, a crowd of difficulties will have occurred to him. Some of them are so serious that to this day I can hardly reflect on them without being in some degree staggered...
Стр. 117 - Variations neither useful nor injurious would not be affected by natural selection, and would be left either a fluctuating element, as perhaps we see in certain polymorphic species, or would ultimately become fixed, owing to the nature of the organism and the nature of the conditions.
Стр. 116 - Can it, then, be thought improbable, seeing that variations useful to man have undoubtedly occurred, that other variations, useful in some way to each being in the great and complex battle of life, should occur in the course of many successive generations ? If such do occur, can we doubt (remembering that many more...
Стр. 108 - Again, it may be asked, how is it that varieties, which I have called incipient species, become ultimately converted into good and distinct species, which in most cases obviously differ from each other far more than do the varieties of the same species...
Стр. 132 - To arrive, however, at a just conclusion regarding the formation of the eye, with all its marvellous yet not absolutely perfect characters, it is indispensable that the reason should conquer the imagination; but I have felt the difficulty far too keenly to be surprised at others hesitating to extend the principle of natural selection to so startling a length.