On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeJ. Murray, 1860 - 502 páginas "In considering the Origin of Species, it is quite conceivable that a naturalist, reflecting on the mutual affinities of organic beings, on their embryological relations, their geographical distribution, geological succession, and other such facts, might come to the conclusion that each 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. Naturalists continually refer to external conditions, such as climate, food, & c, as the only possible cause of variation. In one very limited sense, as we shall hereafter see, this may be true; but it is preposterous to attribute to mere external conditions, the structure, for instance, of the woodpecker, with its feet, tail, beak, and tongue, so admirably adapted to catch insects under the bark of trees. In the case of the misseltoe, which draws its nourishment from certain trees, which has seeds that must be transported by certain birds, and which has flowers with separate sexes absolutely requiring the agency of certain insects to bring pollen from one flower to the other, it is equally preposterous to account for the structure of this parasite, with its relations to several distinct organic beings, by the effects of external conditions, or of habit, or of the volition of the plant itself"--Introduction. (PsycINFO Database Record (c) 2012 APA, all rights reserved) |
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Página 51
... continuous , in which case he can hardly hope to find the intermediate links between his doubtful forms , he will have to trust almost entirely to analogy , and his difficulties rise to a climax . Certainly no clear line of demarcation ...
... continuous , in which case he can hardly hope to find the intermediate links between his doubtful forms , he will have to trust almost entirely to analogy , and his difficulties rise to a climax . Certainly no clear line of demarcation ...
Página 106
... continuous , owing to oscillations of level , will often have recently existed in a broken con- dition , so that the good effects of isolation will generally , to a certain extent , have concurred . Finally , I conclude that , although ...
... continuous , owing to oscillations of level , will often have recently existed in a broken con- dition , so that the good effects of isolation will generally , to a certain extent , have concurred . Finally , I conclude that , although ...
Página 174
... continuous , that it has been continuous during a long period . Geology would lead us to believe that almost every continent has been broken up into islands even during the later tertiary periods ; and in such islands distinct species ...
... continuous , that it has been continuous during a long period . Geology would lead us to believe that almost every continent has been broken up into islands even during the later tertiary periods ; and in such islands distinct species ...
Página 175
... continuous area , are gene- rally so distributed that each has a wide range , with a comparatively narrow neutral territory between them , in which they become rather suddenly rarer and rarer ; then , as varieties do not essentially ...
... continuous area , are gene- rally so distributed that each has a wide range , with a comparatively narrow neutral territory between them , in which they become rather suddenly rarer and rarer ; then , as varieties do not essentially ...
Página 178
... continuous must often have existed within the recent period in isolated portions , in which many forms , more especially amongst the classes which unite for each birth and wander much , may have separately been rendered sufficiently ...
... continuous must often have existed within the recent period in isolated portions , in which many forms , more especially amongst the classes which unite for each birth and wander much , may have separately been rendered sufficiently ...
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Términos y frases comunes
adapted affinities allied species America analogous ancient animals become bees believe birds breeds cause cells chapter characters cirripedes climate closely allied colour continuous crossed crustaceans degree difficulty distinct species divergence domestic doubt embryo Europe existing exterminated extinct extremely facts favourable Fcap fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period greater number groups of species habits Hence hermaphrodites History hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing intermediate land larvæ less living male mammals manner migration modification modified descendants natural selection naturalists nearly nest offspring perfect pigeons plants pollen Portrait Post 8vo present principle probably produced progenitor racter ranked reciprocal crosses remarked resemble rudimentary organs Second Edition seeds sexual selection Silurian slight South America sterility structure struggle successive supposed theory Third Edition tion variability variations varieties vary Vols widely Woodcuts