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 57
... , to whom I lie under deep obligation for assistance of all kinds , has marked for me 182 British plants , which are generally considered as varieties , but which have all been ranked by CHAP . II . ] 57 DOUBTFUL SPECIES .
... , to whom I lie under deep obligation for assistance of all kinds , has marked for me 182 British plants , which are generally considered as varieties , but which have all been ranked by CHAP . II . ] 57 DOUBTFUL SPECIES .
Página 59
... considered as species and which as varieties . " Lastly , representative species fill the same place in the natural economy of each island as do the local forms and sub - species ; but as they are distin- guished from each other by a ...
... considered as species and which as varieties . " Lastly , representative species fill the same place in the natural economy of each island as do the local forms and sub - species ; but as they are distin- guished from each other by a ...
Página 61
... considered by highly - competent judges to be varieties , resemble species so completely in character , that they have been thus ranked by other highly - competent judges . But to discuss whether they ought to be called species or ...
... considered by highly - competent judges to be varieties , resemble species so completely in character , that they have been thus ranked by other highly - competent judges . But to discuss whether they ought to be called species or ...
Página 62
... considered by other botanists to be varieties ; and in this country the highest botanical authorities and practical men can be quoted to show that the sessile and pedunculated oaks are either good and distinct species or mere varieties ...
... considered by other botanists to be varieties ; and in this country the highest botanical authorities and practical men can be quoted to show that the sessile and pedunculated oaks are either good and distinct species or mere varieties ...
Página 73
... considered necessary to give to any two forms the rank of species cannot be defined . In genera having more than the average number of species in any country , the species of these genera have more than the average number of varieties ...
... considered necessary to give to any two forms the rank of species cannot be defined . In genera having more than the average number of species in any country , the species of these genera have more than the average number of varieties ...
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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