On the origin of species by means of natural selection ; or, The preservation of favored races in the struggle for lifeD. Appleton and Company, 1875 - Всего страниц: 458 |
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Стр. 38
... ranked as distinct species by many entomologists . Even Ireland has a few animals , now generally regarded as varieties , but which have been ranked as species by some zoologists . Several experienced ornithologists consider our British ...
... ranked as distinct species by many entomologists . Even Ireland has a few animals , now generally regarded as varieties , but which have been ranked as species by some zoologists . Several experienced ornithologists consider our British ...
Стр. 39
... ranked by all entomologists as good species . But no observer can determine for another , even if he can do so for himself , which of these Phytophagic forms ought to be called species and which varietics . Mr. Walsh ranks the forms ...
... ranked by all entomologists as good species . But no observer can determine for another , even if he can do so for himself , which of these Phytophagic forms ought to be called species and which varietics . Mr. Walsh ranks the forms ...
Стр. 40
... ranked by some authors as species . Look at the common oak , how closely it has been studied ; yet a German author makes more than a dozen species out of forms , which are almost universally considered by other botanists to be varieties ...
... ranked by some authors as species . Look at the common oak , how closely it has been studied ; yet a German author makes more than a dozen species out of forms , which are almost universally considered by other botanists to be varieties ...
Стр. 45
... ranked as species or varioties . Now Fries has remarked in regard to plants , and Westwood in regard to insects , that in large genera the amount of difference between the species is often exceedingly small . CHAP . II . 45 Specics of ...
... ranked as species or varioties . Now Fries has remarked in regard to plants , and Westwood in regard to insects , that in large genera the amount of difference between the species is often exceedingly small . CHAP . II . 45 Specics of ...
Стр. 46
... ranked as species , but which he considers as so closely allied to other species as to be of doubtful value : these 63 reputed species range on an average over 6-9 of the provinces into which Mr. Watson has divided Great Britain . Now ...
... ranked as species , but which he considers as so closely allied to other species as to be of doubtful value : these 63 reputed species range on an average over 6-9 of the provinces into which Mr. Watson has divided Great Britain . Now ...
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adapted admit affinities allied species America analogous ancient appear beak become bees believe belonging birds breeds cause cells characters climate closely allied colour continued crossed crustaceans degree developed difficulty distinct species doubt effects eggs embryo existing extinct extremely facts favourable fertilised fertility flowers formations formerly forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hybrids important 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 occasionally occur oceanic islands offspring organisation organs parent peculiar perfect pigeon pistil pollen present principle probably produced quadrupeds ranked reciprocal crosses remarked reproductive resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure struggle successive supposed theory tion variability variations varieties vary whilst whole wings young
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Стр. 50 - I should premise that I use this term in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny.
Стр. 63 - It has been said that I speak of natural selection as an active power or Deity; but who objects to an author speaking of the attraction of gravity as ruling the movements of the planets ? Every one knows what is meant and is implied by such metaphorical expressions; and they are almost necessary for brevity.
Стр. 65 - 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 bear the stamp of far higher workmanship...
Стр. 143 - 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. 3 - As many more individuals of each species are born than can possibly survive ; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected.
Стр. 56 - ... there was a large and extremely barren heath, which had never been touched by the hand of man ; but several hundred acres of exactly the same nature had been enclosed twenty-five years previously and planted with Scotch fir. The change in the native vegetation of the planted part of the heath was most remarkable, more than is generally seen in passing from one quite different soil to another ; not only the proportional numbers of the heath-plants were wholly changed, but twelve species of plants...
Стр. 49 - 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. Yet unless it be thoroughly engrained in the mind, the whole economy of nature, with every fact on distribution, rarity, abundance, extinction, and variation, will be dimly seen or quite misunderstood.
Стр. 48 - ... we see beautiful adaptations everywhere and in every part of the organic world.
Стр. 69 - The result is not death to the unsuccessful competitor but few or no offspring. Sexual selection is, therefore, less rigorous than natural selection. Generally the most vigorous males, those which are best fitted for their places in nature, will leave most progeny. But in many cases victory depends not so much on general vigor as on having special weapons, confined to the male sex. A hornless stag or spurless cock would have a poor chance of leaving numerous offspring.
Стр. 412 - What limit can be put to this power, acting during long ages and rigidly scrutinising the whole constitution, structure, and habits of each creature, — favouring the good and rejecting the bad ? I can see no limit to this power, in slowly and beautifully adapting each form to the most complex relations of life.