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 xviii
... follows : - " All species might have been varieties once , and many va- rieties are gradually becoming species by assuming con- stant and peculiar characters ; " but farther on ( p . 18 ) he adds , " except the original types or ...
... follows : - " All species might have been varieties once , and many va- rieties are gradually becoming species by assuming con- stant and peculiar characters ; " but farther on ( p . 18 ) he adds , " except the original types or ...
Página xx
... follows : - " The archetypal idea was manifested in the flesh under divers such modifications , upon this planet , long prior to the existence of those animal species that actually exemplify it . To what natural laws or secondary causes ...
... follows : - " The archetypal idea was manifested in the flesh under divers such modifications , upon this planet , long prior to the existence of those animal species that actually exemplify it . To what natural laws or secondary causes ...
Página 5
... follows from the high geo- metrical ratio of their increase , will be considered . This is the doctrine of Malthus , applied to the whole animal and vegetable kingdoms . As many more individuals of each species are born than can ...
... follows from the high geo- metrical ratio of their increase , will be considered . This is the doctrine of Malthus , applied to the whole animal and vegetable kingdoms . As many more individuals of each species are born than can ...
Página 10
... follows from the crossing of distinct species , and that which may be observed with plants and ani- mals when reared under new or unnatural condi- tions . Many facts clearly show how eminently sus- ceptible the reproductive system is to ...
... follows from the crossing of distinct species , and that which may be observed with plants and ani- mals when reared under new or unnatural condi- tions . Many facts clearly show how eminently sus- ceptible the reproductive system is to ...
Página 36
... follow it as a trade : the sheep are placed on a table and are studied , like a picture by a connoisseur ; this is done three times at intervals of months , and the sheep are each time marked and classed , so that the very best may ...
... follow it as a trade : the sheep are placed on a table and are studied , like a picture by a connoisseur ; this is done three times at intervals of months , and the sheep are each time marked and classed , so that the very best may ...
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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