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 13
... crossed offspring from a short - horned cow by a long - horned bull , the greater length of horn , though appearing late in life , is clearly due to the male element . Having alluded to the subject of reversion , I may here refer to a ...
... crossed offspring from a short - horned cow by a long - horned bull , the greater length of horn , though appearing late in life , is clearly due to the male element . Having alluded to the subject of reversion , I may here refer to a ...
Página 14
... crossing , that only a single variety should be turned loose in its new home . Nevertheless , as our varieties certainly do occasionally revert in some of their characters to ancestral forms , it seems to me not improbable , that if we ...
... crossing , that only a single variety should be turned loose in its new home . Nevertheless , as our varieties certainly do occasionally revert in some of their characters to ancestral forms , it seems to me not improbable , that if we ...
Página 15
... crossed , ―a subject hereafter to be discussed ) , domestic races of the same species differ from each other in the same manner as , only in most cases in a lesser degree than , do closely - allied species of the same genus in a state ...
... crossed , ―a subject hereafter to be discussed ) , domestic races of the same species differ from each other in the same manner as , only in most cases in a lesser degree than , do closely - allied species of the same genus in a state ...
Página 18
... crossing of a few aboriginal species ; but by crossing we can only get forms in some degree intermediate between their parents ; and if we account for our several domestic races by this process , we must admit the former existence of ...
... crossing of a few aboriginal species ; but by crossing we can only get forms in some degree intermediate between their parents ; and if we account for our several domestic races by this process , we must admit the former existence of ...
Página 19
... crossed one with another for several generations , hardly two of them will be alike , and then the extreme difficulty , or rather utter hopelessness , of the task becomes apparent . Certainly , a breed intermediate between two very ...
... crossed one with another for several generations , hardly two of them will be alike , and then the extreme difficulty , or rather utter hopelessness , of the task becomes apparent . Certainly , a breed intermediate between two very ...
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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