The Origin of Species by Means of Natural Selection,: Or the Preservation of Favoured Races in the Struggle for LifeJohn Murray, Albemarle Street., 1891 - 432 páginas |
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Página xx
... separated from the extinct by new creations , but are to be regarded as their descendants through continued reproduction . " A well - known French botanist , M. Lecoq , writes in 1854 ( ' Etudes sur Géograph . Bot . , ' tom . i . p ...
... separated from the extinct by new creations , but are to be regarded as their descendants through continued reproduction . " A well - known French botanist , M. Lecoq , writes in 1854 ( ' Etudes sur Géograph . Bot . , ' tom . i . p ...
Página 6
... separated by any distinct line from slighter variations . All such changes of structure , whether extremely slight or strongly marked , which appear amongst many individuals living together , may be considered as the indefinite effects ...
... separated by any distinct line from slighter variations . All such changes of structure , whether extremely slight or strongly marked , which appear amongst many individuals living together , may be considered as the indefinite effects ...
Página 34
... separated areas . How many of the birds and insects in North America and Europe , which differ very slightly from each other , have been ranked by one eminent naturalist as undoubted species , and by another as varieties , or , as they ...
... separated areas . How many of the birds and insects in North America and Europe , which differ very slightly from each other , have been ranked by one eminent naturalist as undoubted species , and by another as varieties , or , as they ...
Página 68
... separation of the sexes of plants . Some holly - trees bear only male flowers , which have four stamens producing a rather small quantity of pollen , and a rudimentary pistil ; other holly - trees bear only female flowers ; these have a ...
... separation of the sexes of plants . Some holly - trees bear only male flowers , which have four stamens producing a rather small quantity of pollen , and a rudimentary pistil ; other holly - trees bear only female flowers ; these have a ...
Página 69
... separation of the sexes of our plant would be advantageous on the principle of the division of labour , individuals with this tendency more and more increased , would be continually favoured or selected , until at last a complete separation ...
... separation of the sexes of our plant would be advantageous on the principle of the division of labour , individuals with this tendency more and more increased , would be continually favoured or selected , until at last a complete separation ...
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Términos y frases comunes
accumulated adapted admit affinities allied species America analogous ancient appear beak become bees believe belonging birds breeds cause cells characters climate closely allied colour continued crossed crustaceans degree developed difficulty distinct species domestic animals doubt effects eggs embryo existing extinct extremely facts favourable female fertilised fertility flowers formation formerly forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number habits Hence hybrids 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 occur oceanic islands offspring organisation organs parent peculiar perfect pigeon pistil pollen present preserved principle probably produced quadrupeds ranked reciprocal crosses remarked resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure successive supposed tend theory tion variability variations varieties vary whilst whole wings young