The Origin of Species by Means of Natural Selection: Or the Preservation of Favored Races in the Struggle for LifeD. Appleton, 1904 - 435 páginas |
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Página 60
... living on different plants , have been observed by Mr. Walsh to present in their larval or mature state , or in both states , slight , though constant differences in colour , size , or in the nature of their secretions . In some ...
... living on different plants , have been observed by Mr. Walsh to present in their larval or mature state , or in both states , slight , though constant differences in colour , size , or in the nature of their secretions . In some ...
Página 130
... living fos- sils ; they have endured to the present day , from having inhabited a confined area , and from having been exposed to less varied , and therefore less severe , competition . To sum up , as far as the extreme intricacy of the ...
... living fos- sils ; they have endured to the present day , from having inhabited a confined area , and from having been exposed to less varied , and therefore less severe , competition . To sum up , as far as the extreme intricacy of the ...
Página 137
... living on the same piece of ground . And we know that each species and each variety of grass is annu- ally sowing almost countless seeds ; and is thus striv- ing , as it may be said , to the utmost to increase in num- ber . Consequently ...
... living on the same piece of ground . And we know that each species and each variety of grass is annu- ally sowing almost countless seeds ; and is thus striv- ing , as it may be said , to the utmost to increase in num- ber . Consequently ...
Página 139
... living in the United States . By considering the nature of the plants or animals which have in any country struggled successfully with the indigenes and have there become naturalised , we may gain some crude idea in what manner some of ...
... living in the United States . By considering the nature of the plants or animals which have in any country struggled successfully with the indigenes and have there become naturalised , we may gain some crude idea in what manner some of ...
Página 149
... living , yet are often , in some degree , intermediate in character between existing groups ; and we can understand this fact , for the extinct species lived at various remote epochs when the branching lines of descent had diverged less ...
... living , yet are often , in some degree , intermediate in character between existing groups ; and we can understand this fact , for the extinct species lived at various remote epochs when the branching lines of descent had diverged less ...
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Términos y frases comunes
adapted affinities allied species America ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters climate closely allied colour common continent crossed crustaceans degree developed difficulty distinct species domestic doubt effects eggs embryo existing extinct extremely facts favourable fertilised fertility flowers formation forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hybrids important individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living males mammals manner marsupials migration modified descendants natural selection naturalists nearly nest occasionally offspring organisation organs parent peculiar perfect pigeon pistil pollen present principle probably produced progenitor quadrupeds ranked remarked resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure successive supposed swimbladder tend theory tion trees variability variations varieties vary whilst whole wings young