The Origin of SpeciesP.F. Collier, 1909 - Всего страниц: 552 |
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Стр. 26
... offspring are either definite or indefinite . They may be considered as definite when all or nearly all the offspring of individuals exposed to certain conditions during several generations are modified in the same manner . It is ...
... offspring are either definite or indefinite . They may be considered as definite when all or nearly all the offspring of individuals exposed to certain conditions during several generations are modified in the same manner . It is ...
Стр. 28
... offspring somewhat unlike their parents . I may add , that as some organisms breed freely under the most unnat- ural conditions ( for instance , rabbits and ferrets kept in hutches ) , showing that their reproductive organs are not ...
... offspring somewhat unlike their parents . I may add , that as some organisms breed freely under the most unnat- ural conditions ( for instance , rabbits and ferrets kept in hutches ) , showing that their reproductive organs are not ...
Стр. 31
... offspring at a corresponding age , though sometimes earlier . In many cases this could not be otherwise ; thus the inherited pecu- liarities in the horns of cattle could appear only in the off- spring when nearly mature ; peculiarities ...
... offspring at a corresponding age , though sometimes earlier . In many cases this could not be otherwise ; thus the inherited pecu- liarities in the horns of cattle could appear only in the off- spring when nearly mature ; peculiarities ...
Стр. 32
... offspring from a short - horned cow by a long - horned bull , though appearing late in life , is clearly due to the male element . Having alluded to the subject of aversion , I may here refer to a statement often made by naturalists ...
... offspring from a short - horned cow by a long - horned bull , though appearing late in life , is clearly due to the male element . Having alluded to the subject of aversion , I may here refer to a statement often made by naturalists ...
Стр. 34
... offspring of any single species , then such facts would have great weight in making us doubt about the immuta- bility of the many closely allied natural species - for in- stance , of the many foxes - inhabiting different quarters of the ...
... offspring of any single species , then such facts would have great weight in making us doubt about the immuta- bility of the many closely allied natural species - for in- stance , of the many foxes - inhabiting different quarters of the ...
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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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Стр. 78 - 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.
Стр. 22 - ... 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.
Стр. 94 - 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...
Стр. 90 - 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.
Стр. 77 - 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.
Стр. 46 - 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.
Стр. 188 - 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. 192 - 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?
Стр. 527 - 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...
Стр. 140 - 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...