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 31
... points of structure with all the domestic breeds . Secondly , that , although an English carrier or a short - faced tumbler differs immensely in certain characters from the rock - pigeon , yet that , by comparing the several sub ...
... points of structure with all the domestic breeds . Secondly , that , although an English carrier or a short - faced tumbler differs immensely in certain characters from the rock - pigeon , yet that , by comparing the several sub ...
Página 38
... point do not differ at all in other points ; this is hardly ever , I speak after careful observation , -perhaps never , the case . The law of correlated variation , the importance of which should never be overlooked , will ensure some ...
... point do not differ at all in other points ; this is hardly ever , I speak after careful observation , -perhaps never , the case . The law of correlated variation , the importance of which should never be overlooked , will ensure some ...
Página 44
... points of the breed . Nor let it be thought that some great deviation of structure would be necessary to catch the fancier's eye : he perceives extremely small differences , and it is in human nature to value any novelty , however ...
... points of the breed . Nor let it be thought that some great deviation of structure would be necessary to catch the fancier's eye : he perceives extremely small differences , and it is in human nature to value any novelty , however ...
Página 45
... points of value are once ac- knowledged , the principle , as I have called it , of un- conscious selection will always tend , -perhaps more at one period than at another , as the breed rises or falls in fashion , perhaps more in one ...
... points of value are once ac- knowledged , the principle , as I have called it , of un- conscious selection will always tend , -perhaps more at one period than at another , as the breed rises or falls in fashion , perhaps more in one ...
Página 53
... point of view , sometimes vary in the individuals of the same species . I am convinced that the most experienced naturalist would be surprised at the number of the cases of variability , even in impor- tant parts of structure , which he ...
... point of view , sometimes vary in the individuals of the same species . I am convinced that the most experienced naturalist would be surprised at the number of the cases of variability , even in impor- tant parts of structure , which he ...
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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