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 142
... difficulty , more especially under changing conditions of life , in the continued preservation of individuals with fuller and fuller flank - membranes , each modification being useful , each being propagated , until by the accumulated ...
... difficulty , more especially under changing conditions of life , in the continued preservation of individuals with fuller and fuller flank - membranes , each modification being useful , each being propagated , until by the accumulated ...
Página 236
... difficulty , which at first appeared to me insuperable , and actually fatal to the whole theory . I allude to the neuters or sterile females in insect - communities ; for these neuters often differ widely in instinct and in structure ...
... difficulty , which at first appeared to me insuperable , and actually fatal to the whole theory . I allude to the neuters or sterile females in insect - communities ; for these neuters often differ widely in instinct and in structure ...
Página 330
... difficulty in believing that they have migrated from the same region ; for during the vast geographical and climatal changes which have supervened since ancient times , almost any amount of migration is possible . But in many other ...
... difficulty in believing that they have migrated from the same region ; for during the vast geographical and climatal changes which have supervened since ancient times , almost any amount of migration is possible . But in many other ...
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