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 8
... male and female reproductive elements having been affected prior to the act of con- ception . Several reasons make me believe in this ; but the chief one is the remarkable effect which confine- ment or cultivation has on the function of ...
... male and female reproductive elements having been affected prior to the act of con- ception . Several reasons make me believe in this ; but the chief one is the remarkable effect which confine- ment or cultivation has on the function of ...
Página 13
... males alone . A much more important rule , which I think may be trusted , is that , at whatever period of life a ... male element ; in nearly the same manner as in the crossed offspring from a short - horned cow by a long - horned bull ...
... males alone . A much more important rule , which I think may be trusted , is that , at whatever period of life a ... male element ; in nearly the same manner as in the crossed offspring from a short - horned cow by a long - horned bull ...
Página 19
... male bird , is also remarkable from the wonderful development of the carunculated skin about the head , and this is accompanied by greatly elongated eyelids , very large external orifices to the nostrils , and a wide gape of mouth . The ...
... male bird , is also remarkable from the wonderful development of the carunculated skin about the head , and this is accompanied by greatly elongated eyelids , very large external orifices to the nostrils , and a wide gape of mouth . The ...
Página 21
... males and females have come to differ to a slight degree from each other . Altogether at least a score of pigeons might be chosen , which if shown to an ornithologist , and he were told that they were wild birds , would certainly , I ...
... males and females have come to differ to a slight degree from each other . Altogether at least a score of pigeons might be chosen , which if shown to an ornithologist , and he were told that they were wild birds , would certainly , I ...
Página 26
... male and female pigeons can be easily mated for life ; and thus different breeds can be kept together in the same aviary . I have discussed the probable origin of domestic pigeons at some , yet quite insufficient , length ; because when ...
... male and female pigeons can be easily mated for life ; and thus different breeds can be kept together in the same aviary . I have discussed the probable origin of domestic pigeons at some , yet quite insufficient , length ; because when ...
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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