On the Origin of Species by Means of Natural Selection, Or, The Preservation of Favoured Races in the Struggle for LifeAppleton, 1898 - Всего страниц: 432 |
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Стр. 3
... fertilised with their own pollen , and ( ex- cluding all cases such as the Leguminosa , in which there is an acknowledged difficulty in the manipulation ) half of these twenty plants had their fertility in some degree impaired ...
... fertilised with their own pollen , and ( ex- cluding all cases such as the Leguminosa , in which there is an acknowledged difficulty in the manipulation ) half of these twenty plants had their fertility in some degree impaired ...
Стр. 5
... fertilised during each generation by pollen from the same flower ; and this would probably be injurious to their fertility , already lessened by their hybrid origin . I am strengthened in this conviction by a remarkable statement ...
... fertilised during each generation by pollen from the same flower ; and this would probably be injurious to their fertility , already lessened by their hybrid origin . I am strengthened in this conviction by a remarkable statement ...
Стр. 6
... fertilised hybrids , in contrast with those spontaneously self - fertilised , may , as I believe , be accounted for by too close interbreeding having been avoided . Now let us turn to the results arrived at by a third most experienced ...
... fertilised hybrids , in contrast with those spontaneously self - fertilised , may , as I believe , be accounted for by too close interbreeding having been avoided . Now let us turn to the results arrived at by a third most experienced ...
Стр. 7
... fertilised by pollen from the same individual plant ! To give one instance , a bulb of Hippeastrum aulicum produced four flowers ; three were fertilised by Herbert with their own pollen , and the fourth was subsequently fertilised by ...
... fertilised by pollen from the same individual plant ! To give one instance , a bulb of Hippeastrum aulicum produced four flowers ; three were fertilised by Herbert with their own pollen , and the fourth was subsequently fertilised by ...
Стр. 12
... fertilised hybrids producing a greater and greater number of seeds up to perfect fer- tility . The hybrids raised from two species which are very difficult to cross , and which rarely produce any off- spring , are generally very sterile ...
... fertilised hybrids producing a greater and greater number of seeds up to perfect fer- tility . The hybrids raised from two species which are very difficult to cross , and which rarely produce any off- spring , are generally very sterile ...
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The Origin of Species by Means of Natural Selection: Or, The ..., Том 1 Charles Darwin Полный просмотр - 1889 |
The Origin of Species by Means of Natural Selection: Or, the ..., Том 1 Charles Darwin Полный просмотр - 1898 |
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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