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 |
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Página 65
... occur with our game animals - often ensue and here we have a limiting check independent of the struggle for life . But even some of these so - called epidemics appear to be due to parasitic worms , which have from some cause , possibly ...
... occur with our game animals - often ensue and here we have a limiting check independent of the struggle for life . But even some of these so - called epidemics appear to be due to parasitic worms , which have from some cause , possibly ...
Página 73
... occurred , that other variations useful in some way to each being in the great and com- plex battle of life , should sometimes occur in the course of thousands of generations ? If such do occur , can we doubt ( remembering that many ...
... occurred , that other variations useful in some way to each being in the great and com- plex battle of life , should sometimes occur in the course of thousands of generations ? If such do occur , can we doubt ( remembering that many ...
Página 75
... occurring ; and unless profitable variations do occur , natural selection can do nothing . Not that , as I believe , any extreme amount of variability is necessary ; as man can certainly produce great results by adding up in any given ...
... occurring ; and unless profitable variations do occur , natural selection can do nothing . Not that , as I believe , any extreme amount of variability is necessary ; as man can certainly produce great results by adding up in any given ...
Página 80
... occurs under nature , and if so , natural selection will be able to modify one sex in its functional rela- tions to the other sex , or in relation to wholly different habits of life in the two sexes , as is sometimes the case with ...
... occurs under nature , and if so , natural selection will be able to modify one sex in its functional rela- tions to the other sex , or in relation to wholly different habits of life in the two sexes , as is sometimes the case with ...
Página 85
... 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 the division of ...
... 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 the division of ...
Otras ediciones - Ver todas
On the Origin of Species by Means of Natural Selection: or the Preservation ... Charles Darwin Vista previa limitada - 2023 |
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