On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeEaston Press, 1976 - 470 páginas |
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... reproductive system being affected , we may infer that variability is thus induced , partly from the fact of this system being extremely sensitive to any change in the conditions , and partly from the similarity , as Kölreuter and ...
... reproductive system being affected , we may infer that variability is thus induced , partly from the fact of this system being extremely sensitive to any change in the conditions , and partly from the similarity , as Kölreuter and ...
Página 258
... reproductive systems having been specially affected , though in a lesser degree than when sterility ensues . So it is with hybrids , for their offspring in successive generations are eminently liable to vary , as every experimentalist ...
... reproductive systems having been specially affected , though in a lesser degree than when sterility ensues . So it is with hybrids , for their offspring in successive generations are eminently liable to vary , as every experimentalist ...
Página 268
... reproductive systems in any way affected , and they are not variable ; but hybrids themselves have their reproductive systems seriously affected , and their descendants are highly variable . But to return to our comparison of mongrels ...
... reproductive systems in any way affected , and they are not variable ; but hybrids themselves have their reproductive systems seriously affected , and their descendants are highly variable . But to return to our comparison of mongrels ...
Contenido
VARIATION UNDER NATURE | 30 |
STRUGGLE FOR EXISTENCE | 45 |
NATURAL SELECTION | 59 |
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Términos y frases comunes
accumulated adapted admit affinities allied species America ancient appear beak become bees believe belonging birds breeds cause cells characters climate closely allied colour common progenitor continuous crossed crustaceans degree developed difficulty distinct species divergence doubt effects eggs embryo existing exterminated extinct extremely facts favourable fertilised fertility flowers formation forms fossil Fritz Müller genera genus geological geological period gradations greater number groups of species habits Hence hybrids hybrids produced important increase individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living male mammals manner marsupials migration modified descendants natural selection naturalists nearly nest occasionally offspring organisation organs Origin of Species parent peculiar perfect pigeons pistil plants pollen present preserved principle probably produced quadrupeds ranked reciprocal crosses remarked resemblance rudimentary seeds slight South America stamens sterility structure struggle successive supposed swimbladder theory variability variations varieties vary whilst whole wings young