The Origin of Species by Means of Natural Selection: Or the Preservation of Favored Races in the Struggle for LifeD. Appleton, 1904 - 435 páginas |
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Página 47
... seen it gravely remarked , that it was most fortunate that the strawberry began to vary just when gardeners began to attend to this plant . No doubt the strawberry had always varied since it was cultivated , but the slight varieties had ...
... seen it gravely remarked , that it was most fortunate that the strawberry began to vary just when gardeners began to attend to this plant . No doubt the strawberry had always varied since it was cultivated , but the slight varieties had ...
Página 58
... seen to be so slight and graduated , that it is impossible to define or describe them , though at the same time the extreme forms are sufficiently distinct . The geographical races or sub - species are local forms completely fixed and ...
... seen to be so slight and graduated , that it is impossible to define or describe them , though at the same time the extreme forms are sufficiently distinct . The geographical races or sub - species are local forms completely fixed and ...
Página 66
... seen that I look at the term species as one arbitrarily given , for the sake of convenience , to a set of individuals closely resembling each other , and that it does not essentially differ from the term variety , which is given to less ...
... seen that I look at the term species as one arbitrarily given , for the sake of convenience , to a set of individuals closely resembling each other , and that it does not essentially differ from the term variety , which is given to less ...
Página 74
... seen that it is the most flourishing or dominant species of the larger genera within each class which on an average yield the greatest number of varieties ; and varieties , as we shall hereafter see , tend to become converted into new ...
... seen that it is the most flourishing or dominant species of the larger genera within each class which on an average yield the greatest number of varieties ; and varieties , as we shall hereafter see , tend to become converted into new ...
Página 75
... seen in the last chapter that amongst organic beings in a state of nature there is some individual variability : indeed I am not aware that this has ever been disputed . It is immaterial for us whether a mul- titude of doubtful forms be ...
... seen in the last chapter that amongst organic beings in a state of nature there is some individual variability : indeed I am not aware that this has ever been disputed . It is immaterial for us whether a mul- titude of doubtful forms be ...
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Términos y frases comunes
adapted affinities allied species America ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters climate closely allied colour common continent crossed crustaceans degree developed difficulty distinct species domestic doubt effects eggs embryo existing extinct extremely facts favourable fertilised fertility flowers formation forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hybrids important individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living males mammals manner marsupials migration modified descendants natural selection naturalists nearly nest occasionally offspring organisation organs parent peculiar perfect pigeon pistil pollen present principle probably produced progenitor quadrupeds ranked remarked resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure successive supposed swimbladder tend theory tion trees variability variations varieties vary whilst whole wings young