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 vii
... crossing - Fertility of varieties when crossed and of their mongrel offspring not universal - Hybrids and mongrels compared independently of their fertility - Summary 245-278 CHAPTER IX . ON THE IMPERFECTION OF THE GEOLOGICAL RECORD.
... crossing - Fertility of varieties when crossed and of their mongrel offspring not universal - Hybrids and mongrels compared independently of their fertility - Summary 245-278 CHAPTER IX . ON THE IMPERFECTION OF THE GEOLOGICAL RECORD.
Página 14
... crossed offspring from a short- horned cow by a long - horned bull , the greater length of horn , though appearing late in life , is clearly due to the male element . Having alluded to the subject of reversion , I may here refer to a ...
... crossed offspring from a short- horned cow by a long - horned bull , the greater length of horn , though appearing late in life , is clearly due to the male element . Having alluded to the subject of reversion , I may here refer to a ...
Página 16
... crossed , -a subject hereafter to be discussed ) , domestic races of the same species differ from each other in the same manner as , only in most cases in a lesser degree than , do closely- allied species of the same genus in a state of ...
... crossed , -a subject hereafter to be discussed ) , domestic races of the same species differ from each other in the same manner as , only in most cases in a lesser degree than , do closely- allied species of the same genus in a state of ...
Página 19
... . - so unlike all wild Canida -ever existed freely in a state of nature ? It has often been loosely said that all our races of dogs have been produced by the crossing of a few aboriginal species. CHAP . I. 19 UNDER DOMESTICATION .
... . - so unlike all wild Canida -ever existed freely in a state of nature ? It has often been loosely said that all our races of dogs have been produced by the crossing of a few aboriginal species. CHAP . I. 19 UNDER DOMESTICATION .
Página 20
... crossing of a few aboriginal species ; but by crossing we can only get forms in some degree intermediate between their parents ... crossed one with another for several generations , hardly two of them will be alike , and then the extreme ...
... crossing of a few aboriginal species ; but by crossing we can only get forms in some degree intermediate between their parents ... crossed one with another for several generations , hardly two of them will be alike , and then the extreme ...
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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