The Origin of Species by Means of Natural Selection, Or, The Preservation of Favored Races in the Struggle for Life, Volúmenes1-2D. Appleton, 1917 |
Contenido
VARIATION UNDER DOMESTICATION | 7 |
CHAPTER II | 51 |
STRUGGLE FOR EXISTENCE | 66 |
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Términos y frases comunes
adapted affinity allied species ancient animals appear Archipelago beak become believe belonging birds breeds Cambrian cause characters climate closely allied colour common continent crossed crustaceans degree developed difficulty distinct species domestic doubt eggs embryo Europe existing extinct extremely facts favourable fertilised fertility fish flowers formation formerly forms fossil Fritz Müller Gärtner genera genus geological geological period Glacial period gradations groups of species habits Hence hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing intermediate land larvæ less living male mammals manner Marsupials migration modified descendants natural selection naturalists nearly occur oceanic islands offspring organisation parent peculiar perfect pigeon pistil plants pollen present probably produced progenitor quadrupeds ranked reciprocal crosses remarked resemblance seeds Silurian slight South America stage stamens sterility structure successive suppose theory tion variability variations varieties vary whilst whole widely different wings