On the Origin of Species by Means of Natural Selection, Or, The Preservation of Favoured Races in the Struggle for LifeAppleton, 1898 |
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Página 4
... varieties , and found them absolutely sterile , we may doubt whether many species are really so sterile , when intercrossed , as he be- lieved . It is certain , on the one hand , that the sterility of various species when crossed is so ...
... varieties , and found them absolutely sterile , we may doubt whether many species are really so sterile , when intercrossed , as he be- lieved . It is certain , on the one hand , that the sterility of various species when crossed is so ...
Página 15
... varieties . It is also a remarkable fact , that hybrids raised from reciprocal crosses , though of course compounded of the very same two species , the one spe- cies having first been used as the father and then as the mother , though ...
... varieties . It is also a remarkable fact , that hybrids raised from reciprocal crosses , though of course compounded of the very same two species , the one spe- cies having first been used as the father and then as the mother , though ...
Página 18
... varieties of the pear take with different de- grees of facility on the quince ; so do different varie- ties of the apricot and peach on certain varieties of the plum . As Gärtner found that there was sometimes an innate difference in ...
... varieties of the pear take with different de- grees of facility on the quince ; so do different varie- ties of the apricot and peach on certain varieties of the plum . As Gärtner found that there was sometimes an innate difference in ...
Página 20
... varieties or incipient species , if they could be kept from blending , on the same principle that , when man is selecting at the same time two varieties , it is necessary that he should keep them separate . In the first place , it may ...
... varieties or incipient species , if they could be kept from blending , on the same principle that , when man is selecting at the same time two varieties , it is necessary that he should keep them separate . In the first place , it may ...
Página 32
... varieties ( and such occur ) of the long - styled form of the trimorphic Lythrum salicaria , and that he determined to try by crossing whether they were specifically distinct . He would find that they yielded only about one - fifth of ...
... varieties ( and such occur ) of the long - styled form of the trimorphic Lythrum salicaria , and that he determined to try by crossing whether they were specifically distinct . He would find that they yielded only about one - fifth of ...
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Términos y frases comunes
admit affinity allied species ancient animals appear Archipelago arctic areas become believe birds Cambrian changes characters cies classification climate closely allied common progenitor continent crustaceans degree deposited difficulty distant distinct species domestic doubt embryo eral Europe existing extinct fact faunas fertilised fertility flowers formations formerly forms fossil fresh-water Fritz Müller Gärtner genera genus geological period geological record Glacial period groups of species habits hybrids hybrids produced important individuals inhabitants inherited insects instance intermediate intervals land larvæ less living mammals manner marine Marsupials migration modified descendants mongrels mountains natural selection naturalists nearly occur oceanic islands offspring organisation parent parent-form peculiar perfect pistil plants pollen present probably produced quadrupeds reciprocal crosses regions remains remarked reproductive resemblance rocks rudimentary organs sediment seeds Silurian South America stage stamens sterility structure successive suppose terrestrial tertiary theory tion variations varieties whilst widely different wings