The Origin of Species by Means of Natural Selection,: Or the Preservation of Favoured Races in the Struggle for LifeAppleton, 1898 - 432 páginas |
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Página 11
... remarked , that the degree of fertility , both of first crosses and of hybrids , graduates from zero to perfect fertility . It is surprising in how many curious ways this gradation can be shown ; but CHAP . IX . ] 11 DEGREES OF STERILITY .
... remarked , that the degree of fertility , both of first crosses and of hybrids , graduates from zero to perfect fertility . It is surprising in how many curious ways this gradation can be shown ; but CHAP . IX . ] 11 DEGREES OF STERILITY .
Página 20
... remarked that species inhabiting distinct regions are often sterile when crossed ; now it could clearly have been of no advantage to such sepa- rated species to have been rendered mutually sterile , and consequently this could not have ...
... remarked that species inhabiting distinct regions are often sterile when crossed ; now it could clearly have been of no advantage to such sepa- rated species to have been rendered mutually sterile , and consequently this could not have ...
Página 52
... remarked , the extent and thickness of our sedimentary formations are the result and the measure of the denudation which the earth's crust has elsewhere undergone . Therefore a man should examine for himself the great piles of super ...
... remarked , the extent and thickness of our sedimentary formations are the result and the measure of the denudation which the earth's crust has elsewhere undergone . Therefore a man should examine for himself the great piles of super ...
Página 73
... remarked , " Every species is a link " between other allied forms . " If we take a genus having a score of species , recent and extinct , and de- stroy four - fifths of them , no one doubts that the re- mainder will stand much more ...
... remarked , " Every species is a link " between other allied forms . " If we take a genus having a score of species , recent and extinct , and de- stroy four - fifths of them , no one doubts that the re- mainder will stand much more ...
Página 85
... remarked , certainly preyed on other minute organic beings , which must have lived in great numbers . Thus the words , which I wrote in 1859 , about the existence of living beings long before the Cambrian period , and which are almost ...
... remarked , certainly preyed on other minute organic beings , which must have lived in great numbers . Thus the words , which I wrote in 1859 , about the existence of living beings long before the Cambrian period , and which are almost ...
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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