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 10
... fact of this system being extremely sensitive to any change in the conditions , and partly from the similarity , as ... facts clearly show how eminently sus- ceptible the reproductive system is to very slight changes in the surrounding ...
... fact of this system being extremely sensitive to any change in the conditions , and partly from the similarity , as ... facts clearly show how eminently sus- ceptible the reproductive system is to very slight changes in the surrounding ...
Página 13
... facts collected by Heusinger , it appears that white sheep and pigs are injured by certain plants , whilst dark - coloured individuals escape : Professor Wy- man has recently communicated to me a good illustra- tion of this fact ; on ...
... facts collected by Heusinger , it appears that white sheep and pigs are injured by certain plants , whilst dark - coloured individuals escape : Professor Wy- man has recently communicated to me a good illustra- tion of this fact ; on ...
Página 16
... facts make me believe that the rule has a wider extension , and that , when there is no apparent reason why a peculiarity should appear at any particular age , yet that it does tend to appear in the offspring at the same period at which ...
... facts make me believe that the rule has a wider extension , and that , when there is no apparent reason why a peculiarity should appear at any particular age , yet that it does tend to appear in the offspring at the same period at which ...
Página 21
... facts , come to the conclusion that several wild species of Canidæ have been tamed , and that their blood , in some cases mingled together , flows in the veins of our do- mestic breeds . In regard to sheep and goats I can form no ...
... facts , come to the conclusion that several wild species of Canidæ have been tamed , and that their blood , in some cases mingled together , flows in the veins of our do- mestic breeds . In regard to sheep and goats I can form no ...
Página 29
... facts , on the well - known principle of reversion to ancestral characters , if all the domestic breeds are descended from the rock - pigeon . But if we deny this , we must make one of the two following highly improbable suppositions ...
... facts , on the well - known principle of reversion to ancestral characters , if all the domestic breeds are descended from the rock - pigeon . But if we deny this , we must make one of the two following highly improbable suppositions ...
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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