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 23
... characters ; for instance , I crossed some uniformly white fantails with some uniformly black barbs , and they produced mottled brown and black birds ; these I again crossed together , and one grandchild of the pure white fantail and ...
... characters ; for instance , I crossed some uniformly white fantails with some uniformly black barbs , and they produced mottled brown and black birds ; these I again crossed together , and one grandchild of the pure white fantail and ...
Página 24
... characters , if all the domestic breeds have descended from the rock - pigeon . But if we deny this , we must make ... character derived from such cross will naturally become less and less , as in each succeeding genera- tion there will ...
... characters , if all the domestic breeds have descended from the rock - pigeon . But if we deny this , we must make ... character derived from such cross will naturally become less and less , as in each succeeding genera- tion there will ...
Página 25
... characters in certain re- spects , as compared with all other Columbida , though so like in most other respects to the rock - pigeon ; the blue colour and various marks occasionally appearing in all the breeds , both when kept pure and ...
... characters in certain re- spects , as compared with all other Columbida , though so like in most other respects to the rock - pigeon ; the blue colour and various marks occasionally appearing in all the breeds , both when kept pure and ...
Página 31
... characters . It may be objected that the principle of selection has been reduced to methodical practice for scarcely more than three - quarters of a century ; it has certainly been more attended to of late years , and many treatises ...
... characters . It may be objected that the principle of selection has been reduced to methodical practice for scarcely more than three - quarters of a century ; it has certainly been more attended to of late years , and many treatises ...
Página 35
... character of our domestic races , and likewise their differences being so great in external characters and relatively so slight in internal parts or organs . Man can hardly select , or only with much difficulty , any deviation of ...
... character of our domestic races , and likewise their differences being so great in external characters and relatively so slight in internal parts or organs . Man can hardly select , or only with much difficulty , any deviation of ...
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