On the Origin of Species by Means of Natural Selection: Or The Preservation of Favoured Races in the Struggle for LifeHumphrey Milford, Oxford University Press, 1923 - 454 páginas |
Dentro del libro
Resultados 1-5 de 40
Página 24
... species closely related together , though it is unsupported by a single experiment . But to ex- tend the hypothesis so far as to suppose that species , aboriginally as distinct as carriers , tumblers , pouters , 24 ON THE ORIGIN OF SPECIES.
... species closely related together , though it is unsupported by a single experiment . But to ex- tend the hypothesis so far as to suppose that species , aboriginally as distinct as carriers , tumblers , pouters , 24 ON THE ORIGIN OF SPECIES.
Página 28
... suppose that all the breeds were suddenly produced as perfect and as useful as we now see them ; indeed , in several cases , we know that this has not been their history . The key is man's power of accumulative selection : nature gives ...
... suppose that all the breeds were suddenly produced as perfect and as useful as we now see them ; indeed , in several cases , we know that this has not been their history . The key is man's power of accumulative selection : nature gives ...
Página 82
... suppose that the fleetest prey , a deer for instance , had from any change in the country increased in numbers , or that other prey had decreased in numbers , during that season of the year when the wolf is hardest pressed for food . I ...
... suppose that the fleetest prey , a deer for instance , had from any change in the country increased in numbers , or that other prey had decreased in numbers , during that season of the year when the wolf is hardest pressed for food . I ...
Página 83
... suppose a little sweet juice or nectar to be excreted by the inner bases of the petals of a flower . In this case insects in seeking the nectar would get dusted with pollen , and would certainly often transport the pollen from one ...
... suppose a little sweet juice or nectar to be excreted by the inner bases of the petals of a flower . In this case insects in seeking the nectar would get dusted with pollen , and would certainly often transport the pollen from one ...
Página 85
... suppose this to occur in ever so slight a degree under nature , then as pollen is already carried regularly from flower to flower , and as a more complete separa- tion of the sexes of our plant would be advantageous on the principle of ...
... suppose this to occur in ever so slight a degree under nature , then as pollen is already carried regularly from flower to flower , and as a more complete separa- tion of the sexes of our plant would be advantageous on the principle of ...
Otras ediciones - Ver todas
Términos y frases comunes
accumulated adapted affinities allied species America amount analogous ancient appear Archipelago become bees believe birds breeds cause cells characters cirripedes climate closely allied colour common parent continuous crossed crustaceans degree difficulty distinct species divergence doubt embryo endemic Europe existing exterminated extinct extremely facts favourable fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hermaphrodites hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing land larvæ less living male mammals manner Marsupials migration modification modified descendants natural selection naturalists nearly nest oceanic islands offspring organisation perfect pigeons pistil plants pollen present principle probably produced progenitor ranked reciprocal crosses remarked resemble rock-pigeon rudimentary organs seeds sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder tend theory tion trees variability variation vary whole widely