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 54
... bees do not visit this flower . I have also found that the visits of bees are necessary for the fertilisation of some kinds of clover ; for instance , 20 heads of Dutch clover ( Trifolium repens ) yielded 2,290 seeds , but 20 other ...
... bees do not visit this flower . I have also found that the visits of bees are necessary for the fertilisation of some kinds of clover ; for instance , 20 heads of Dutch clover ( Trifolium repens ) yielded 2,290 seeds , but 20 other ...
Página 230
... bees instantly began on both sides to excavate little basins near to each other , in the same way as before ; but the ridge of wax was so thin , that the bottoms of the basins , if they had been excavated to the same depths as in the ...
... bees instantly began on both sides to excavate little basins near to each other , in the same way as before ; but the ridge of wax was so thin , that the bottoms of the basins , if they had been excavated to the same depths as in the ...
Página 233
... bees in a hive for the secretion of the wax necessary for the construction of their combs . Moreover , many bees have to remain idle for many days during the process of secretion . A large store of honey is indispensable to support a ...
... bees in a hive for the secretion of the wax necessary for the construction of their combs . Moreover , many bees have to remain idle for many days during the process of secretion . A large store of honey is indispensable to support a ...
Contenido
VARIATION UNDER NATURE | 30 |
STRUGGLE FOR EXISTENCE | 45 |
NATURAL SELECTION | 59 |
Derechos de autor | |
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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