The Origin of SpeciesP.F. Collier, 1909 - 552페이지 |
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31 페이지
... stage . But hereditary diseases and some other facts make me believe that the rule has a wider extension , and that , when there is no apparent reason why a peculiarity should appear at any particular age , yet that it does tend to ...
... stage . But hereditary diseases and some other facts make me believe that the rule has a wider extension , and that , when there is no apparent reason why a peculiarity should appear at any particular age , yet that it does tend to ...
50 페이지
... stages through which they have insensibly passed , and come to differ so greatly from the rock - pigeon . Youatt gives an excellent illustration of the effects of a course of selection , which may be considered as unconscious , in so ...
... stages through which they have insensibly passed , and come to differ so greatly from the rock - pigeon . Youatt gives an excellent illustration of the effects of a course of selection , which may be considered as unconscious , in so ...
68 페이지
... stage of difference to another may , in many cases , be the simple result of the nature of the organism and of the different physical conditions to which it has long been ex- posed ; but with respect to the more important and adaptive ...
... stage of difference to another may , in many cases , be the simple result of the nature of the organism and of the different physical conditions to which it has long been ex- posed ; but with respect to the more important and adaptive ...
99 페이지
... stages of the varieties of the silkworm ; in the eggs of poultry , and in the colour of the down of their chickens ; in the horns of our sheep and cattle when nearly adult ; -so in a state of nature natural selection will be enabled to ...
... stages of the varieties of the silkworm ; in the eggs of poultry , and in the colour of the down of their chickens ; in the horns of our sheep and cattle when nearly adult ; -so in a state of nature natural selection will be enabled to ...
123 페이지
... stage of development . THE PROBABLE EFFECTS OF THE ACTION OF NATURAL SELECTION THROUGH DIVERGENCE OF CHARACTER AND EXTINC- TION , ON THE DESCENDANTS OF A COMMON ANCESTOR After the foregoing discussion , which has been much com- pressed ...
... stage of development . THE PROBABLE EFFECTS OF THE ACTION OF NATURAL SELECTION THROUGH DIVERGENCE OF CHARACTER AND EXTINC- TION , ON THE DESCENDANTS OF A COMMON ANCESTOR After the foregoing discussion , which has been much com- pressed ...
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자주 나오는 단어 및 구문
adapted admit affinities allied species America analogous ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters cirripedes climate closely allied colour common continent crossed crustaceans degree developed difficulty distinct species domestic doubt eggs embryo existing extinct extremely facts favourable fertilised fertility flowers formation forms fossil Fritz Müller genera genus geological geological period Glacial period gradations groups of species habits Hence hybrids important increase individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living male mammals manner Marsupials migration modified descendants natural selection naturalists nearly nest offspring organisation organs parent peculiar perfect pigeon pistil pollen present principle probably produced progenitor quadrupeds ranked reciprocal crosses remarked resemblance rudimentary seeds sexual selection slight South America stamens sterility structure successive supposed tend theory tion trees variability variations varieties vary whilst whole wings young
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78 페이지 - Nothing is easier than to admit in words the truth of the universal struggle for life, or more difficult — at least I have found it so — than constantly to bear this conclusion in mind.
22 페이지 - ... species had not been independently created, but had descended, like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how the innumerable species inhabiting this world have been modified, so as to acquire that perfection of structure and coadaptation which justly excites our admiration.
94 페이지 - If such do occur, can we doubt (remembering that many more individuals are born than can possibly survive) that individuals having any advantage, however slight, over others, would have the best chance of surviving and of procreating their kind ? On the other hand, we may feel sure that any variation in the least degree injurious would be rigidly destroyed. This preservation of favourable individual differences and variations, and the destruction of those which are injurious, I have called Natural...
90 페이지 - We can dimly see why the competition should be most severe between allied forms which fill nearly the same place in the economy of nature, but probably in no one case could we precisely' say why one species has been victorious over another in the great battle of life.
77 페이지 - I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection, in order to mark its relation to man's power of selection. But the expression often used by Mr. Herbert Spencer of the Survival of the Fittest is more accurate, and is sometimes equally convenient.
46 페이지 - We cannot suppose that all the c— HC x1 breeds were suddenly produced as perfect and as useful as we now see them ; indeed, in many cases, we know that this has not been their history. The key is man's power of accumulative selection : nature gives successive variations ; man adds them up in certain directions useful to him.
188 페이지 - 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.
192 페이지 - Let this process go on for millions of years; and during each year on millions of individuals of many kinds; and may we not believe that a living optical instrument might thus be formed as superior to one of glass, as the works of the Creator are to those of man?
527 페이지 - Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are...
140 페이지 - It is a truly wonderful fact — the wonder of which we are apt to overlook from familiarity — that all animals and all plants throughout all time and space should be related to each other in groups, subordinate to groups, in the manner which we everywhere behold...