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 45
... genera . Under genera , including the most polymorphic forms , Mr. Babington gives 251 species , whereas Mr. Ben- tham gives only 112 , -a difference of 139 doubtful forms ! Amongst animals which unite for each birth , and which are ...
... genera . Under genera , including the most polymorphic forms , Mr. Babington gives 251 species , whereas Mr. Ben- tham gives only 112 , -a difference of 139 doubtful forms ! Amongst animals which unite for each birth , and which are ...
Página 50
... genera being placed on one side , and all those in the smaller genera on the other side , a some- what larger number of the very common and much diffused or dominant species will be found on the side of the larger genera . This , again ...
... genera being placed on one side , and all those in the smaller genera on the other side , a some- what larger number of the very common and much diffused or dominant species will be found on the side of the larger genera . This , again ...
Página 51
... genera in each country would oftener present varieties , than the species of the smaller genera ; for wherever many closely - related species ( i.e. species of the same genus ) have been formed , many varieties or incipient species ...
... genera in each country would oftener present varieties , than the species of the smaller genera ; for wherever many closely - related species ( i.e. species of the same genus ) have been formed , many varieties or incipient species ...
Página 52
... genera are now varying much , and are thus increasing in the number of their species , or that no small genera are now varying and increasing ; for if this had been so , it would have been fatal to my theory ; inasmuch as geology ...
... genera are now varying much , and are thus increasing in the number of their species , or that no small genera are now varying and increasing ; for if this had been so , it would have been fatal to my theory ; inasmuch as geology ...
Página 53
... genera . Or the case may be put in another way , and it may be said , that in the larger genera , in which a number of varieties or incipient species greater than the average are now manufacturing , many of the species already ...
... genera . Or the case may be put in another way , and it may be said , that in the larger genera , in which a number of varieties or incipient species greater than the average are now manufacturing , many of the species already ...
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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