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 6-10 de 100
Página 47
... forms , which are very generally considered as varieties ; and in this country the highest botanical authorities and ... forms . His general tendency will be to make many species , for he will become impressed , just like the pigeon or ...
... forms , which are very generally considered as varieties ; and in this country the highest botanical authorities and ... forms . His general tendency will be to make many species , for he will become impressed , just like the pigeon or ...
Página 52
... forms , naturalists are compelled to come to a deter- mination by the amount of difference between them , judging by analogy whether or not the amount suffices to raise one or both to the rank of species . Hence the amount of difference ...
... forms , naturalists are compelled to come to a deter- mination by the amount of difference between them , judging by analogy whether or not the amount suffices to raise one or both to the rank of species . Hence the amount of difference ...
Página 53
... forms , unequally related to each other , and clustered round certain forms - that is , round their parent - species ? Undoubt- edly there is one most important point of difference between varieties and species ; namely , that the ...
... forms , unequally related to each other , and clustered round certain forms - that is , round their parent - species ? Undoubt- edly there is one most important point of difference between varieties and species ; namely , that the ...
Página 54
... forms , and the occurrence of such links cannot affect the actual characters of the forms which they connect ; and except , secondly , by a certain amount of difference , for two forms , if differing very little , are generally ranked ...
... forms , and the occurrence of such links cannot affect the actual characters of the forms which they connect ; and except , secondly , by a certain amount of difference , for two forms , if differing very little , are generally ranked ...
Página 55
... forms of life which are now dominant tend to become still more dominant by leaving many modified and dominant descendants . But by steps hereafter to be explained , the larger genera also tend to break up into smaller genera . And thus ...
... forms of life which are now dominant tend to become still more dominant by leaving many modified and dominant descendants . But by steps hereafter to be explained , the larger genera also tend to break up into smaller genera . And thus ...
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