On the Origin of Species by Means of Natural Selection: Or The Preservation of Favored Races in the Struggle for Life, Volumen2D. Appleton, 1888 - 458 páginas |
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Página viii
... occasional means --Dispersal during the Glacial period Alternate Glacial periods in - the north and south .. 316-342 ― CHAPTER XIII . GEOGRAPHICAL DISTRIBUTION - continued . Distribution of fresh - water productions -- On the ...
... occasional means --Dispersal during the Glacial period Alternate Glacial periods in - the north and south .. 316-342 ― CHAPTER XIII . GEOGRAPHICAL DISTRIBUTION - continued . Distribution of fresh - water productions -- On the ...
Página 6
... occasionally appear in the young of the same litter , and in seedlings from the same seed - capsule . At long intervals of time , out of millions or individuals reared in the same country and fed on nearly the same food , deviations of ...
... occasionally appear in the young of the same litter , and in seedlings from the same seed - capsule . At long intervals of time , out of millions or individuals reared in the same country and fed on nearly the same food , deviations of ...
Página 11
... occasionally revert in some of their characters to ancestral forms , it seems to me not improbable that if we could succeed in naturalising , or were to cultivate , during many generations , the several races , for instance , of the ...
... occasionally revert in some of their characters to ancestral forms , it seems to me not improbable that if we could succeed in naturalising , or were to cultivate , during many generations , the several races , for instance , of the ...
Página 15
... occasional crosses , if aided by the careful selection of the individuals which present the desired character ; but to obtain a race intermediate between two quite distinct races , would be very difficult . Sir J. Sebright expressly ...
... occasional crosses , if aided by the careful selection of the individuals which present the desired character ; but to obtain a race intermediate between two quite distinct races , would be very difficult . Sir J. Sebright expressly ...
Página 20
... occasional re - appearance of the blue colour and various black marks in all the breeds , both when kept pure and when crossed ; -and lastly , the mongrel off- spring being perfectly fertile ; -from these several reasons , taker ...
... occasional re - appearance of the blue colour and various black marks in all the breeds , both when kept pure and when crossed ; -and lastly , the mongrel off- spring being perfectly fertile ; -from these several reasons , taker ...
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Términos y frases comunes
adapted admit affinities allied species America analogous ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters climate closely allied colour continued crossed crustaceans degree developed difficulty distinct species doubt effects eggs embryo existing extinct extremely facts favourable fertilised fertility flowers formation formerly forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number habits Hence hybrids important 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 occur oceanic islands offspring organisation organs parent peculiar perfect pigeon pistil pollen present preserved principle probably produced quadrupeds ranked reciprocal crosses remarked reproductive resemblance rudimentary seeds sexual selection slight South America stamens sterility structure struggle successive supposed tend theory tion variability variations varieties vary whilst whole wings young