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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49 페이지
... hybrid nature of the in- termediate links always remove the difficulty . In very many cases , however , one form is ranked as a variety of another , not because the intermediate links have actually been found , but because analogy leads ...
... hybrid nature of the in- termediate links always remove the difficulty . In very many cases , however , one form is ranked as a variety of another , not because the intermediate links have actually been found , but because analogy leads ...
51 페이지
... 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 be ranked as varieties . Close investigation , in most cases , will ...
... 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 be ranked as varieties . Close investigation , in most cases , will ...
92 페이지
... hybrids between distinct species ; for if you bring on the same brush a plant's own pollen and pollen from another species , the former will have such a prepotent effect , that it will invariably and com- pletely destroy , as has been ...
... hybrids between distinct species ; for if you bring on the same brush a plant's own pollen and pollen from another species , the former will have such a prepotent effect , that it will invariably and com- pletely destroy , as has been ...
148 페이지
... have been the product of a zebra ; and Mr. W. C. Martin , in his excellent treatise on the horse , has given a figure of a similar mule . In four coloured draw- ings , which I have seen , of hybrids between 148 [ CHAP . LAWS OF VARIATION .
... have been the product of a zebra ; and Mr. W. C. Martin , in his excellent treatise on the horse , has given a figure of a similar mule . In four coloured draw- ings , which I have seen , of hybrids between 148 [ CHAP . LAWS OF VARIATION .
149 페이지
... hybrids between the ass and zebra , the legs were much more plainly barred than the rest of the body ; and in one of them there was a double shoulder - stripe . In Lord Moreton's famous hybrid from a chestnut mare and male quagga , the ...
... hybrids between the ass and zebra , the legs were much more plainly barred than the rest of the body ; and in one of them there was a double shoulder - stripe . In Lord Moreton's famous hybrid from a chestnut mare and male quagga , the ...
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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.