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 xxi
... distinct have descended from a single parent - form . In June , 1859 , Professor Huxley gave a lecture before the Royal Institution on the Persistent Types of Animal life . ' Referring to such cases , he remarks , " It is difficult to ...
... distinct have descended from a single parent - form . In June , 1859 , Professor Huxley gave a lecture before the Royal Institution on the Persistent Types of Animal life . ' Referring to such cases , he remarks , " It is difficult to ...
Página 13
... distinct species . In the case of strongly marked races of some other domesticated species , there is presumptive or even strong evidence , that all are descended from a single wild stock . It has often been assumed that man has chosen ...
... distinct species . In the case of strongly marked races of some other domesticated species , there is presumptive or even strong evidence , that all are descended from a single wild stock . It has often been assumed that man has chosen ...
Página 15
... distinct races by crossing has been greatly exaggerated . Many cases are on record , showing that a race may be modified by occasional crosses , if aided by the careful selection of the individuals which present the desired character ...
... distinct races by crossing has been greatly exaggerated . Many cases are on record , showing that a race may be modified by occasional crosses , if aided by the careful selection of the individuals which present the desired character ...
Página 19
... distinct breeds . Now , hardly any cases have been ascertained with certainty of hybrids from two quite distinct species of animals being perfectly fertile . Some authors believe that long - continued domestication eliminates this ...
... distinct breeds . Now , hardly any cases have been ascertained with certainty of hybrids from two quite distinct species of animals being perfectly fertile . Some authors believe that long - continued domestication eliminates this ...
Página 26
... distinct strains . The two flocks of Leicester sheep kept by Mr. Buckley and Mr. Burgess , as Mr. Youatt remarks ... distinct to be ranked at their first appearance as distinct varieties , and whether or not two or more species or races ...
... distinct strains . The two flocks of Leicester sheep kept by Mr. Buckley and Mr. Burgess , as Mr. Youatt remarks ... distinct to be ranked at their first appearance as distinct varieties , and whether or not two or more species or races ...
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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