The Origin of Species, Том 2Books, Incorporated, 1900 - Всего страниц: 365 |
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Стр. 242
... pollen of the same kind , their fertility , not- withstanding the frequent ill effects from manipulation , some- times decidedly increases , and goes on increasing . Now , in the process of artificial fertilization , pollen is as often ...
... pollen of the same kind , their fertility , not- withstanding the frequent ill effects from manipulation , some- times decidedly increases , and goes on increasing . Now , in the process of artificial fertilization , pollen is as often ...
Стр. 257
... pollen- grains . With trimorphic plants there are three forms likewise differing in the lengths of their pistils and stamens , in the size and color of the pollen - grains , and in some other respects ; and as in each of the three forms ...
... pollen- grains . With trimorphic plants there are three forms likewise differing in the lengths of their pistils and stamens , in the size and color of the pollen - grains , and in some other respects ; and as in each of the three forms ...
Стр. 258
... pollen is strongly prepotent over illegitimate pollen , when both are placed on the same stigma . I ascertained this by fertilizing several flowers , first illegitimately and twenty - four hours afterward legitimately , with pollen ...
... pollen is strongly prepotent over illegitimate pollen , when both are placed on the same stigma . I ascertained this by fertilizing several flowers , first illegitimately and twenty - four hours afterward legitimately , with pollen ...
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adapted admit affinity ancient animals appear Archipelago areas become believe belonging birds Cambrian characters classification climate closely allied species common continent creation crustaceans degree deposits descent with modification developed difficulty distant distinct species domestic doubt embryo Europe existing extinct facts faunas 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 INDIANENSIS individuals inhabitants inherited insects instance intermediate intervals land larvæ less living mammæ mammals manner marine Marsupials MDCCCXX migration modified descendants mongrels mountains natural selection naturalists nearly oceanic islands offspring parent peculiar perfect pistil plants pollen present probably produced progenitor quadrupeds reciprocal crosses regions remains remarked reproductive resemblance rocks rudimentary organs seeds SIGILLUM Silurian South America stage stamens sterility structure successive suppose terrestrial tertiary theory of natural tion variations varieties VERITAS whole widely different