The Origin of species

accumulated adapted ancient appear Asa Gray beak become bees believe birds breeds cause chapter characters climate closely allied colour common continent crossed crustaceans Darwin degree developed difficulty distinct species divergence domestic races doubt edition effects eggs embryo existing extinct extremely facts favourable female fertilised fertility flowers formation forms fossil Fritz Müller genera genus geological Glacial period gradations greater number groups habits Hence hermaphrodites Hooker hybrids important increase individuals inhabitants inherited insects instance instincts intercrossing intermediate islands kind lamellæ lancelet larvæ less living LLCD males mammals manner migration natural selection naturalists nearly occasionally occur offspring organisation organs origin ORIGIN OF SPECIES parent perfect pigeons pollen pollen-grains present preserved principle probably produced progenitor quadrupeds ranked relation remarked resemble rudimentary seeds sexual selection Silurian slight Space stamens sterility structure struggle supposed tend theory tion trees variability variations varieties vary whilst whole widely young