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 28
... variability . We cannot suppose that all the breeds were suddenly produced as perfect and as useful as we now see them ; indeed , in several cases , we know that this has not been their history . The key is man's power of accumulative ...
... variability . We cannot suppose that all the breeds were suddenly produced as perfect and as useful as we now see them ; indeed , in several cases , we know that this has not been their history . The key is man's power of accumulative ...
Página 37
... variability is obviously favourable , as freely giving the materials for selection to work on ; not that mere individual differences are not amply sufficient , with extreme care , to allow of the accumula- tion of a large amount of ...
... variability is obviously favourable , as freely giving the materials for selection to work on ; not that mere individual differences are not amply sufficient , with extreme care , to allow of the accumula- tion of a large amount of ...
Página 39
... variability . I do not believe that variability is an inherent and necessary contingency , under all circumstances , with all organic beings , as some authors have thought . The effects of variability are modified by various degrees of ...
... variability . I do not believe that variability is an inherent and necessary contingency , under all circumstances , with all organic beings , as some authors have thought . The effects of variability are modified by various degrees of ...
Página 40
... variability both of hybrids and mongrels , and the frequent sterility of hybrids ; but the cases of plants not propagated by seed are of little importance to us , for their endurance is only temporary . Over all these causes of Change I ...
... variability both of hybrids and mongrels , and the frequent sterility of hybrids ; but the cases of plants not propagated by seed are of little importance to us , for their endurance is only temporary . Over all these causes of Change I ...
Página 41
... Variability - Individual differences - Doubtful species - Wide ranging , much diffused , and common species vary most - Species of the larger genera in any country vary more than the species of the smaller genera - Many of the species ...
... Variability - Individual differences - Doubtful species - Wide ranging , much diffused , and common species vary most - Species of the larger genera in any country vary more than the species of the smaller genera - Many of the species ...
Otras ediciones - Ver todas
On the Origin of Species by Means of Natural Selection: or the Preservation ... Charles Darwin Vista previa limitada - 2023 |
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