On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeEaston Press, 1976 - 470 páginas |
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Página 165
... fertilised by the wind it never has a gaily - coloured corolla . Several plants habitually produce two kinds of flowers ; one kind open and coloured so as to attract insects ; the other closed , not coloured , destitute of nectar , and ...
... fertilised by the wind it never has a gaily - coloured corolla . Several plants habitually produce two kinds of flowers ; one kind open and coloured so as to attract insects ; the other closed , not coloured , destitute of nectar , and ...
Página 244
... fertilised during each generation by pollen from the same flower ; and this would probably be injurious to their fertility , already lessened by their hybrid origin . I am strengthened in this conviction by a remarkable statement ...
... fertilised during each generation by pollen from the same flower ; and this would probably be injurious to their fertility , already lessened by their hybrid origin . I am strengthened in this conviction by a remarkable statement ...
Página 256
... fertilised ; and in the majority of the fertilised eggs , the embryos had either been partially developed and had then perished , or had become nearly mature , but the young chickens had been unable to break through the shell . Of the ...
... fertilised ; and in the majority of the fertilised eggs , the embryos had either been partially developed and had then perished , or had become nearly mature , but the young chickens had been unable to break through the shell . Of the ...
Contenido
VARIATION UNDER NATURE | 30 |
STRUGGLE FOR EXISTENCE | 45 |
NATURAL SELECTION | 59 |
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Términos y frases comunes
accumulated adapted admit affinities allied species America ancient appear beak become bees believe belonging birds breeds cause cells characters climate closely allied colour common progenitor continuous crossed crustaceans degree developed difficulty distinct species divergence doubt effects eggs embryo existing exterminated extinct extremely facts favourable fertilised fertility flowers formation forms fossil Fritz Müller genera genus geological geological period gradations greater number groups of species habits Hence hybrids hybrids produced 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 offspring organisation organs Origin of Species parent peculiar perfect pigeons pistil plants pollen present preserved principle probably produced quadrupeds ranked reciprocal crosses remarked resemblance rudimentary seeds slight South America stamens sterility structure struggle successive supposed swimbladder theory variability variations varieties vary whilst whole wings young