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 27
... favourable to Man's Power of Selection . I will now say a few words on the circumstances , favourable , or the reverse , to man's power of selection . A high degree of variability is obviously favourable , as freely giving the materials ...
... favourable to Man's Power of Selection . I will now say a few words on the circumstances , favourable , or the reverse , to man's power of selection . A high degree of variability is obviously favourable , as freely giving the materials ...
Página 28
... favourable . When the individuals are scanty , all will be allowed to breed , whatever their quality may be , and this will effectually prevent selection . But probably the most important element is that the animal or plant should be so ...
... favourable . When the individuals are scanty , all will be allowed to breed , whatever their quality may be , and this will effectually prevent selection . But probably the most important element is that the animal or plant should be so ...
Página 29
... affecting the reproductive system . It is not probable that variability is an inherent and necessary contingent , under all circumstances . The greater or less force of. CHAP . I. ] CIRCUMSTANCES FAVOURABLE TO SELECTION . 29.
... affecting the reproductive system . It is not probable that variability is an inherent and necessary contingent , under all circumstances . The greater or less force of. CHAP . I. ] CIRCUMSTANCES FAVOURABLE TO SELECTION . 29.
Página 31
... favourable circumstances . They would , also , during the first and succeeding generations cross with the ordinary form , and thus their abnormal character would almost inevitably be lost . But I shall have to return in a future chapter ...
... favourable circumstances . They would , also , during the first and succeeding generations cross with the ordinary form , and thus their abnormal character would almost inevitably be lost . But I shall have to return in a future chapter ...
Página 41
... favourable for varia- tion ; and hence we might expect that the circumstances would generally be still favourable to variation . On the other hand , if we look at each species as a special act of creation , there is no apparent reason ...
... favourable for varia- tion ; and hence we might expect that the circumstances would generally be still favourable to variation . On the other hand , if we look at each species as a special act of creation , there is no apparent reason ...
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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