The Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for Life, Volumen2D. Appleton, 1898 |
Dentro del libro
Resultados 1-5 de 37
Página 4
... 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 different in degree and graduates away so insensibly ...
... 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 different in degree and graduates away so insensibly ...
Página 5
... doubt the correctness of this conclusion . Hybrids are seldom raised by experimentalists in great numbers ; and as the parent - species , or other allied hybrids , generally grow in the same garden , the visits of insects must be ...
... doubt the correctness of this conclusion . Hybrids are seldom raised by experimentalists in great numbers ; and as the parent - species , or other allied hybrids , generally grow in the same garden , the visits of insects must be ...
Página 10
... doubt , whether the sev- eral aboriginal species would at first have freely bred together and have produced quite fertile hybrids . So again I have lately acquired decisive evidence that the crossed offspring from the Indian humped and ...
... doubt , whether the sev- eral aboriginal species would at first have freely bred together and have produced quite fertile hybrids . So again I have lately acquired decisive evidence that the crossed offspring from the Indian humped and ...
Página 33
... doubt- ful whether this is really so ; but I will not enlarge on this obscure subject . We may , however , infer as probable from the con- sideration of dimorphic and trimorphic plants , that the sterility of distinct species when ...
... doubt- ful whether this is really so ; but I will not enlarge on this obscure subject . We may , however , infer as probable from the con- sideration of dimorphic and trimorphic plants , that the sterility of distinct species when ...
Página 34
... doubt . For when it is stated , for in- stance , that certain South American indigenous domes- tic dogs do not readily unite with European dogs , the explanation which will occur to every one , and probably the true one , is that they ...
... doubt . For when it is stated , for in- stance , that certain South American indigenous domes- tic dogs do not readily unite with European dogs , the explanation which will occur to every one , and probably the true one , is that they ...
Otras ediciones - Ver todas
Términos y frases comunes
admit affinity allied species ancient animals appear Archipelago arctic areas become believe belonging birds Cambrian changes characters cies classification climate closely allied 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 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 palæontologists Palæozoic parent parent-form peculiar perfect pistil plants pollen present probably produced quadrupeds reciprocal crosses regions remains remarked reproductive resemblance rocks rudimentary organs seeds Silurian South America stage stamens sterility structure successive suppose terrestrial tertiary theory tion variations varieties whilst whole widely different wings