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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Página 142
... become modified , and all analogy would lead us to believe that some at least of the squirrels would decrease in numbers or become exterminated , unless they also become modified and improved in structure in a corresponding manner ...
... become modified , and all analogy would lead us to believe that some at least of the squirrels would decrease in numbers or become exterminated , unless they also become modified and improved in structure in a corresponding manner ...
Página 340
... become widely trans- ported . These means of transport are sometimes called accidental , but this is not strictly correct : the currents of the sea are not accidental , nor is the direction of prevalent gales of wind . It should be ...
... become widely trans- ported . These means of transport are sometimes called accidental , but this is not strictly correct : the currents of the sea are not accidental , nor is the direction of prevalent gales of wind . It should be ...
Página 416
... become reduced in size in the adult descendants of this animal , but would retain nearly its original standard of develop- ment in the embryo . There remains , however , this difficulty . After an organ has ceased being used , and has ...
... become reduced in size in the adult descendants of this animal , but would retain nearly its original standard of develop- ment in the embryo . There remains , however , this difficulty . After an organ has ceased being used , and has ...
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