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 xx
... distinct creations in and for those islands respectively . Always , also , it may be well to bear in mind that by the word ' creation ' the zoologist means a process he knows not what . " He amplifies this idea by adding that when such ...
... distinct creations in and for those islands respectively . Always , also , it may be well to bear in mind that by the word ' creation ' the zoologist means a process he knows not what . " He amplifies this idea by adding that when such ...
Página xxv
... distinct have descended from a single parent - form . In June , 1859 , Professor Huxley gave a lecture be- fore 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 be- fore the Royal Institution on the Persistent Types of Animal Life . ' Referring to such cases , he remarks , " It is difficult to ...
Página 10
... distinct species , and that which may be observed with plants and ani- mals when reared under new or unnatural condi- tions . Many facts clearly show how eminently sus- ceptible the reproductive system is to very slight changes in the ...
... distinct species , and that which may be observed with plants and ani- mals when reared under new or unnatural condi- tions . Many facts clearly show how eminently sus- ceptible the reproductive system is to very slight changes in the ...
Página 23
... 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 30
... 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 ...
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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