On the Origin of Species by Means of Natural Selection: Or The Preservation of Favoured Races in the Struggle for LifeD. Appleton, 1870 - 440페이지 |
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56개의 결과 중 6 - 10개
51 페이지
... intermediate links , and it is very doubt- ful whether these links are hybrids ; and there is , as it seems to me , an overwhelming amount of experimental evidence , showing that they descend from common parents , and consequently must ...
... intermediate links , and it is very doubt- ful whether these links are hybrids ; and there is , as it seems to me , an overwhelming amount of experimental evidence , showing that they descend from common parents , and consequently must ...
52 페이지
... intermediate links between his doubtful forms , he will have to trust almost entirely to analogy , and his difficulties will rise to a climax . Certainly no clear line of demarcation has as yet been drawn between species and sub ...
... intermediate links between his doubtful forms , he will have to trust almost entirely to analogy , and his difficulties will rise to a climax . Certainly no clear line of demarcation has as yet been drawn between species and sub ...
57 페이지
... intermediate links have not been found between doubtful forms , naturalists are compelled to come to a determination by the amount of difference between them , judging by analogy whether or not the amount suffices to raise one or both ...
... intermediate links have not been found between doubtful forms , naturalists are compelled to come to a determination by the amount of difference between them , judging by analogy whether or not the amount suffices to raise one or both ...
58 페이지
... intermediate linking forms , and the occurrence of such links cannot affect the actual characters of the forms which they con- nect ; and except , secondly , by a certain amount of differ- ence , for two forms , if differing very little ...
... intermediate linking forms , and the occurrence of such links cannot affect the actual characters of the forms which they con- nect ; and except , secondly , by a certain amount of differ- ence , for two forms , if differing very little ...
112 페이지
... intermediate forms between the earlier and later states , that is between the less and more improved state . of a species , as well as the original parent - species itself , will generally tend to become extinct . So it probably will be ...
... intermediate forms between the earlier and later states , that is between the less and more improved state . of a species , as well as the original parent - species itself , will generally tend to become extinct . So it probably will be ...
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accumulated adapted affinities allied species America amount analogous ancient animals appear become bees believe birds breeds cause cells chapter characters cirripedes climate closely allied colour continuous crossed crustaceans degree difficulty distinct species disuse divergence domestic doubt embryo endemic Europe existing exterminated extinct extremely facts favourable fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hermaphrodites hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing land larvæ laws less living look male mammals manner migration modification modified descendants natural selection naturalists nearly nest occasional offspring organic organisation perfect pigeons pistil plants pollen present probably produced progenitor ranked reciprocal crosses remarked resemble rudimentary seeds sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder tend theory tion variability variation vary whole widely
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423 페이지 - It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other and dependent upon each other in so complex a manner, have all been produced by laws acting around us.
422 페이지 - In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history.
423 페이지 - Variability from the indirect and direct action of the conditions of life, and from use and disuse; a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less-improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of higher animals, directly follows.
9 페이지 - On my return home, it occurred to me, in 1837, that something might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it. After five years' work I allowed myself to speculate on the subject, and drew up some short notes ; these I enlarged in 1844 into a sketch of the conclusions which then seemed to me probable : from that period to the present day I have steadily pursued the same object. I hope that I may...
423 페이지 - 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 being evolved.
61 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.
72 페이지 - Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice.
169 페이지 - If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.
420 페이지 - Our classifications will come to be, as far as they can be so made, genealogies ; and will then truly give what may be called the plan of creation.
11 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 most justly excites our admiration.