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 49
Página 5
... kind , their fertility , notwithstanding the frequent ill effects from manipulation , sometimes decidedly increases , and goes on increasing . Now , in the process of artificial fertilisa- tion , pollen is as often taken by chance ( as ...
... kind , their fertility , notwithstanding the frequent ill effects from manipulation , sometimes decidedly increases , and goes on increasing . Now , in the process of artificial fertilisa- tion , pollen is as often taken by chance ( as ...
Página 8
... kinds of hy- brid Rhododendrons , which produce no pollen , for he will find on their stigmas plenty of pollen brought from other flowers . men . In regard to animals , much fewer experiments have been carefully tried than with plants ...
... kinds of hy- brid Rhododendrons , which produce no pollen , for he will find on their stigmas plenty of pollen brought from other flowers . men . In regard to animals , much fewer experiments have been carefully tried than with plants ...
Página 14
... kind or what amount of difference , in any recognisable character , is sufficient to prevent two species crossing . It can be shown that plants most widely different in habit and general appearance , and having strongly marked differ ...
... kind or what amount of difference , in any recognisable character , is sufficient to prevent two species crossing . It can be shown that plants most widely different in habit and general appearance , and having strongly marked differ ...
Página 20
... kind of resem- blance and dissimilarity between organic beings is at- tempted to be expressed . The facts by no means seem to indicate that the greater or lesser difficulty of either grafting or crossing various species has been a ...
... kind of resem- blance and dissimilarity between organic beings is at- tempted to be expressed . The facts by no means seem to indicate that the greater or lesser difficulty of either grafting or crossing various species has been a ...
Página 22
... kind , if the theory of natural selection be brought to bear , must have incessantly occurred with many species , for a multitude are mutually quite barren . With sterile neuter insects we have reason to believe that modifica- tions in ...
... kind , if the theory of natural selection be brought to bear , must have incessantly occurred with many species , for a multitude are mutually quite barren . With sterile neuter insects we have reason to believe that modifica- tions in ...
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