The Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeJohn Murray, 1873 - 458페이지 |
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73 페이지
... pistils placed , in relation to the size and habits of the particular insect which visited them , so as to favour in ... pistil , and four stamens with shrivelled anthers , in which not a grain of pollen can be detected . Having found a ...
... pistils placed , in relation to the size and habits of the particular insect which visited them , so as to favour in ... pistil , and four stamens with shrivelled anthers , in which not a grain of pollen can be detected . Having found a ...
74 페이지
... pistils alone in another flower or on another plant . In plants under culture and placed under new conditions of life , sometimes the male organs and sometimes the female organs become more or less impotent ; now if we suppose this to ...
... pistils alone in another flower or on another plant . In plants under culture and placed under new conditions of life , sometimes the male organs and sometimes the female organs become more or less impotent ; now if we suppose this to ...
77 페이지
... pistil stand so near each other as almost to ensure self - fertilisation , the fullest freedom for the entrance of pollen from another individual will explain the above state of exposure of the organs . Many flowers , on the other hand ...
... pistil stand so near each other as almost to ensure self - fertilisation , the fullest freedom for the entrance of pollen from another individual will explain the above state of exposure of the organs . Many flowers , on the other hand ...
78 페이지
... pistil of each cabbage - flower is surrounded not only by its own six stamens , but by those of the many other flowers on the same plant ; and the pollen of each flower readily gets on its own stigma without insect - agency ; for I have ...
... pistil of each cabbage - flower is surrounded not only by its own six stamens , but by those of the many other flowers on the same plant ; and the pollen of each flower readily gets on its own stigma without insect - agency ; for I have ...
97 페이지
... as highest which have every organ , as sepals , petals , stamens , and pistils , fully developed in each flower ; whereas other botanists , H probably with more truth , look at the plants which CHAP . IV . 97 Natural Selection .
... as highest which have every organ , as sepals , petals , stamens , and pistils , fully developed in each flower ; whereas other botanists , H probably with more truth , look at the plants which CHAP . IV . 97 Natural Selection .
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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 continuous 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 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 occasionally oceanic islands offspring organisation organs parent peculiar perfect pigeon pistil pollen present preserved principle probably produced quadrupeds ranked reciprocal crosses remarked reproductive resemblance rudimentary seeds sexual selection slight South America stamens sterility structure struggle successive supposed theory tion variability variations varieties vary whilst whole wings young
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1 페이지 - These facts, as will be seen in the latter chapters of this volume, seemed to throw some light on the origin of species — that mystery of mysteries, as it has been called by one of our greatest philosophers.
162 페이지 - ... if it could be proved that any part of the structure of any one species had been formed for the exclusive good of another species, it would annihilate my theory, for such could not have been produced through natural selection
1 페이지 - ... of our greatest philosophers. 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...
424 페이지 - Analogy would lead me one step further, namely, to the belief that all animals and plants have descended from some one prototype. But analogy may be a deceitful guide.
50 페이지 - In these several senses, which pass into each other, I use for convenience' sake the general term of Struggle for Existence.
322 페이지 - Every species has come into existence coincident both in space and time with a pre-existing closely allied species.
146 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.
310 페이지 - I strongly insisted, in 1839 and 1845, on this " law of the succession of types,"—on " this wonderful relationship in the same continent between the dead and the living." Professor Owen has subsequently extended the same generalisation to the mammals of the Old World. We see the same law in this author's restorations of the extinct and gigantic birds of New Zealand. We see it also in the birds of the caves of Brazil. Mr. Woodward has shown that the same law holds good with sea-shells, but, from...
57 페이지 - Now the number of. mice is largely dependent, as every one knows, on the number of cats; and Col.
103 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...