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 28
... extinct or unknown . So many strange con- tigencies are improbable in the highest degree . Some facts in regard to the colouring of pigeons well deserve consideration . The rock - pigeon is of a slaty- blue , with white loins ; but the ...
... extinct or unknown . So many strange con- tigencies are improbable in the highest degree . Some facts in regard to the colouring of pigeons well deserve consideration . The rock - pigeon is of a slaty- blue , with white loins ; but the ...
Página 63
... extinct , the three sub - species would hold exactly the same relation to each other , as do the four or five provisionally admitted species which closely surround the typical Quercus ro- bur . Finally , De Candolle admits that out of ...
... extinct , the three sub - species would hold exactly the same relation to each other , as do the four or five provisionally admitted species which closely surround the typical Quercus ro- bur . Finally , De Candolle admits that out of ...
Página 65
... extinct , or they may endure as varieties for very long periods , as has been shown to be the case by Mr. Wollas- ton with the varieties of certain fossil land - shells in Madeira , and with plants by Gaston de Saporta . If a variety ...
... extinct , or they may endure as varieties for very long periods , as has been shown to be the case by Mr. Wollas- ton with the varieties of certain fossil land - shells in Madeira , and with plants by Gaston de Saporta . If a variety ...
Página 82
... extinct . It would suffice to keep up the full number of a tree , which lived on an average for a thousand years , if a single seed were produced once in a thousand years , supposing that this seed were never destroyed , and could be ...
... extinct . It would suffice to keep up the full number of a tree , which lived on an average for a thousand years , if a single seed were produced once in a thousand years , supposing that this seed were never destroyed , and could be ...
Página 90
... extinct or very rare in England , the heartsease and red clover would become very rare , or wholly dis- appear . The number of humble - bees in any district depends in a great measure upon the number of field- mice , which destroy their ...
... extinct or very rare in England , the heartsease and red clover would become very rare , or wholly dis- appear . The number of humble - bees in any district depends in a great measure upon the number of field- mice , which destroy their ...
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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