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 17
... single variety should have been turned . loose in its new home . Nevertheless , as our varieties certainly do occasionally revert in some of their charac- ters to ancestral forms , it seems to me not improbable that if we could succeed ...
... single variety should have been turned . loose in its new home . Nevertheless , as our varieties certainly do occasionally revert in some of their charac- ters to ancestral forms , it seems to me not improbable that if we could succeed ...
Página 19
... single species , then such facts would have great weight in making us doubt about the immutability of the many closely allied natural species - for instance , of the many foxes - inhabiting different quarters of the world . I do not ...
... single species , then such facts would have great weight in making us doubt about the immutability of the many closely allied natural species - for instance , of the many foxes - inhabiting different quarters of the world . I do not ...
Página 35
... single lifetime , modified to a large extent their breeds of cattle and sheep . In order fully to realise what they have done , it is almost necessary to read several of the many treatises devoted to this subject , and to inspect the ...
... single lifetime , modified to a large extent their breeds of cattle and sheep . In order fully to realise what they have done , it is almost necessary to read several of the many treatises devoted to this subject , and to inspect the ...
Página 37
... single variation from the aboriginal stock . We have proofs that this has not been so in several cases in which exact records have been kept ; thus , to give a very trifling instance , the steadily - increasing size of the common ...
... single variation from the aboriginal stock . We have proofs that this has not been so in several cases in which exact records have been kept ; thus , to give a very trifling instance , the steadily - increasing size of the common ...
Página 43
... single plant worth culture . It is not that these coun- tries , so rich in species , do not by a strange chance pos- sess the aboriginal stocks of any useful plants , but that the native plants have not been improved by con- tinued ...
... single plant worth culture . It is not that these coun- tries , so rich in species , do not by a strange chance pos- sess the aboriginal stocks of any useful plants , but that the native plants have not been improved by con- tinued ...
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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