The Origin of Species by Means of Natural Selection: Or the Preservation of Favored Races in the Struggle for LifeD. Appleton, 1904 - 435 páginas |
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Página 26
... males and females have come to differ in 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 be ...
... males and females have come to differ in 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 be ...
Página 32
... 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 ...
Página 55
... males of certain Brazilian Crustaceans : thus , the male of a Tanais regularly occurs under two distinct forms ; one of these has strong and differently shaped pincers , and the other has antennæ much more abundantly fur- nished with ...
... males of certain Brazilian Crustaceans : thus , the male of a Tanais regularly occurs under two distinct forms ; one of these has strong and differently shaped pincers , and the other has antennæ much more abundantly fur- nished with ...
Página 56
... male ; and that an hermaphrodite plant should produce from the same seed - capsule three distinct hermaphrodite forms , bear- ing three different kinds of females and three or even six different kinds of males . Nevertheless these cases ...
... male ; and that an hermaphrodite plant should produce from the same seed - capsule three distinct hermaphrodite forms , bear- ing three different kinds of females and three or even six different kinds of males . Nevertheless these cases ...
Página 60
... males alone , in other instances both males and females , have been observed thus to differ in a slight degree . When the differences are rather more strongly marked , and when both sexes and all ages are affected , the forms are ranked ...
... males alone , in other instances both males and females , have been observed thus to differ in a slight degree . When the differences are rather more strongly marked , and when both sexes and all ages are affected , the forms are ranked ...
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Términos y frases comunes
adapted affinities allied species America ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters climate closely allied colour common continent crossed crustaceans degree developed difficulty distinct species domestic doubt effects eggs embryo existing extinct extremely facts favourable fertilised fertility flowers formation forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hybrids important individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living males mammals manner marsupials migration modified descendants natural selection naturalists nearly nest occasionally offspring organisation organs parent peculiar perfect pigeon pistil pollen present principle probably produced progenitor quadrupeds ranked remarked resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure successive supposed swimbladder tend theory tion trees variability variations varieties vary whilst whole wings young