The Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for Life, Volumen2D. Appleton, 1898 |
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Página 2
... common to the two cases , has to be considered . The distinction probably has been slurred over , owing to the sterility in both cases being looked on as a special en- dowment , beyond the province of our reasoning powers . The ...
... common to the two cases , has to be considered . The distinction probably has been slurred over , owing to the sterility in both cases being looked on as a special en- dowment , beyond the province of our reasoning powers . The ...
Página 3
... acknowledged difficulty in the manipulation ) half of these twenty plants had their fertility in some degree impaired . Moreover , as Gärtner repeatedly crossed some forms , such as the common red and. CHAP . IX . ] 3 DEGREES OF STERILITY .
... acknowledged difficulty in the manipulation ) half of these twenty plants had their fertility in some degree impaired . Moreover , as Gärtner repeatedly crossed some forms , such as the common red and. CHAP . IX . ] 3 DEGREES OF STERILITY .
Página 4
... common red and blue pimpernels ( Anagallis arvensis and cœrulea ) , which the best botanists rank as varieties , and found them absolutely sterile , we may doubt whether many species are really so sterile , when intercrossed , as he be ...
... common red and blue pimpernels ( Anagallis arvensis and cœrulea ) , which the best botanists rank as varieties , and found them absolutely sterile , we may doubt whether many species are really so sterile , when intercrossed , as he be ...
Página 5
... common to both parents , this is often transmitted in an augmented degree to the offspring ; and both sexual elements in hybrid plants are already affected in some degree . But I believe that their fertility has been di- minished in ...
... common to both parents , this is often transmitted in an augmented degree to the offspring ; and both sexual elements in hybrid plants are already affected in some degree . But I believe that their fertility has been di- minished in ...
Página 9
... common and Chinese geese ( A. cygnoides ) , species which are so different that they are generally ranked in distinct genera , have often bred in this country with either pure parent , and in one single instance they have bred inter 10 ...
... common and Chinese geese ( A. cygnoides ) , species which are so different that they are generally ranked in distinct genera , have often bred in this country with either pure parent , and in one single instance they have bred inter 10 ...
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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