On the Origin of Species by Means of Natural Selection: Or The Preservation of Favoured Races in the Struggle for LifeHumphrey Milford, Oxford University Press, 1923 - 454 páginas |
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Página 61
... extremely few , is , that the slow - breeders would require a few more years to people , under favourable conditions , a whole district , let it be ever so large . The condor lays a couple of eggs and the ostrich a score , and yet in ...
... extremely few , is , that the slow - breeders would require a few more years to people , under favourable conditions , a whole district , let it be ever so large . The condor lays a couple of eggs and the ostrich a score , and yet in ...
Página 66
... extremely barren heath , which had never been touched by the hand of man ; but several hundred acres of exactly the same nature had been enclosed twenty - five years previously and planted with Scotch fir . The change in the native ...
... extremely barren heath , which had never been touched by the hand of man ; but several hundred acres of exactly the same nature had been enclosed twenty - five years previously and planted with Scotch fir . The change in the native ...
Página 67
... extremely barren and so extensive that no one would ever have imagined that cattle would have so closely and effectually searched it for food . Here we see that cattle absolutely determine the existence of the Scotch fir ; but in ...
... extremely barren and so extensive that no one would ever have imagined that cattle would have so closely and effectually searched it for food . Here we see that cattle absolutely determine the existence of the Scotch fir ; but in ...
Página 70
... extremely close varieties as the variously coloured sweet - peas , they must be each year harvested separately , and the seed then mixed in due proportion , otherwise the weaker kinds will steadily decrease in numbers and disappear . So ...
... extremely close varieties as the variously coloured sweet - peas , they must be each year harvested separately , and the seed then mixed in due proportion , otherwise the weaker kinds will steadily decrease in numbers and disappear . So ...
Página 72
... extremely cold or dry , yet there will be competition between some few species , or between the individuals of the same species , for the warmest or dampest spots . Hence , also , we can see that when a plant or animal is placed in a ...
... extremely cold or dry , yet there will be competition between some few species , or between the individuals of the same species , for the warmest or dampest spots . Hence , also , we can see that when a plant or animal is placed in a ...
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Términos y frases comunes
accumulated adapted affinities allied species America amount analogous ancient appear Archipelago become bees believe birds breeds cause cells characters cirripedes climate closely allied colour common parent continuous crossed crustaceans degree difficulty distinct species divergence 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 less living male mammals manner Marsupials migration modification modified descendants natural selection naturalists nearly nest oceanic islands offspring organisation perfect pigeons pistil plants pollen present principle probably produced progenitor ranked reciprocal crosses remarked resemble rock-pigeon rudimentary organs seeds sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder tend theory tion trees variability variation vary whole widely