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 18
... believe that every race which breeds true , let the distinctive characters be ever so slight , has had its wild prototype . At this rate there must have existed at least a score of species of wild cattle , as many sheep , and several ...
... believe that every race which breeds true , let the distinctive characters be ever so slight , has had its wild prototype . At this rate there must have existed at least a score of species of wild cattle , as many sheep , and several ...
Página 19
... believe . Sir J. Sebright ex- pressly experimentised for this object , and failed . The offspring from the first cross between two pure breeds is tolerably and sometimes ( as I have found with pigeons ) extremely uniform , and ...
... believe . Sir J. Sebright ex- pressly experimentised for this object , and failed . The offspring from the first cross between two pure breeds is tolerably and sometimes ( as I have found with pigeons ) extremely uniform , and ...
Página 21
... believe that any ornithologist would place the English carrier , the short - faced tumbler , the runt , the barb , pouter , and fantail in the same genus ; more especially as in each of these breeds several truly- inherited sub - breeds ...
... believe that any ornithologist would place the English carrier , the short - faced tumbler , the runt , the barb , pouter , and fantail in the same genus ; more especially as in each of these breeds several truly- inherited sub - breeds ...
Página 32
... believe that King Charles's spaniel has been unconsciously modified to a large extent since the time of that monarch . Some highly competent authorities are convinced that the setter is directly derived from the spaniel , and has ...
... believe that King Charles's spaniel has been unconsciously modified to a large extent since the time of that monarch . Some highly competent authorities are convinced that the setter is directly derived from the spaniel , and has ...
Página 39
... believe that the conditions of life , from their action on the reproductive system , are so far of the highest importance as causing variability . I do not believe that variability is an inherent and necessary contingency , under all ...
... believe that the conditions of life , from their action on the reproductive system , are so far of the highest importance as causing variability . I do not believe that variability is an inherent and necessary contingency , under all ...
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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