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 15
... ranked by competent judges as mere varieties , and by other competent judges as the descendants of aborigin- ally distinct species . If any marked distinction ex- isted between domestic races and species , this source of doubt could not ...
... ranked by competent judges as mere varieties , and by other competent judges as the descendants of aborigin- ally distinct species . If any marked distinction ex- isted between domestic races and species , this source of doubt could not ...
Página 34
... ranked at their first appearance as distinct varieties , and whether or not two or more species or races have become blended together by crossing , may plainly be recognised in the increased size and beauty which we now see in the ...
... ranked at their first appearance as distinct varieties , and whether or not two or more species or races have become blended together by crossing , may plainly be recognised in the increased size and beauty which we now see in the ...
Página 45
... ranked by botanists as species ; and in making this list he has omitted many trifling varieties , but which nevertheless have been ranked by some botanists as species , and he has entirely omitted several highly polymorphic genera ...
... ranked by botanists as species ; and in making this list he has omitted many trifling varieties , but which nevertheless have been ranked by some botanists as species , and he has entirely omitted several highly polymorphic genera ...
Página 46
... ranked by other highly - competent judges as good and true species . But to discuss whether they are rightly called species or varieties , before any definition of these terms has been generally accepted , is vainly to beat the air ...
... ranked by other highly - competent judges as good and true species . But to discuss whether they are rightly called species or varieties , before any definition of these terms has been generally accepted , is vainly to beat the air ...
Página 52
... ranked as species or varieties . Now Fries has remarked in regard to plants , and Westwood in regard to insects , that in large genera the amount of difference between the species is often exceedingly small . I have endeavoured to test ...
... ranked as species or varieties . Now Fries has remarked in regard to plants , and Westwood in regard to insects , that in large genera the amount of difference between the species is often exceedingly small . I have endeavoured to test ...
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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