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 35
... region inhabited by quite uncivilised man , has afforded us a single plant worth culture . It is not that these countries , so rich in species , do not by a strange chance possess the abori- ginal stocks of any useful plants , but that ...
... region inhabited by quite uncivilised man , has afforded us a single plant worth culture . It is not that these countries , so rich in species , do not by a strange chance possess the abori- ginal stocks of any useful plants , but that ...
Página 48
... regions ; but I have not much faith in this view ; and I attribute the passage of a variety , from a state in which it differs very slightly from its parent to one in which it differs more , to the action of natural selection in ...
... regions ; but I have not much faith in this view ; and I attribute the passage of a variety , from a state in which it differs very slightly from its parent to one in which it differs more , to the action of natural selection in ...
Página 64
... region to a dry , we invariably see some species gradually getting rarer and rarer , and finally disappearing ; and the ... regions , or snow - capped summits , or absolute deserts , the struggle for life is almost exclusively with the ...
... region to a dry , we invariably see some species gradually getting rarer and rarer , and finally disappearing ; and the ... regions , or snow - capped summits , or absolute deserts , the struggle for life is almost exclusively with the ...
Página 72
... regions or on the borders of an utter desert , will competition cease . The land may be 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 ...
... regions or on the borders of an utter desert , will competition cease . The land may be 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 ...
Página 98
... that natural selection always acts very slowly , often only at long intervals of time , and generally on only a very few of the inhabitants of the same region at the same time . I further believe 98 38 ON THE ORIGIN OF SPECIES.
... that natural selection always acts very slowly , often only at long intervals of time , and generally on only a very few of the inhabitants of the same region at the same time . I further believe 98 38 ON THE ORIGIN OF SPECIES.
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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