The Origin of Species by Means of Natural Selection: Or the Preservation of Favored Races in the Struggle for Life

adapted advantage analogous appear Asa Gray beak become bees believe birds breeds caudicle cause chapter characters climate closely allied colour common continued crossed crustaceans degree developed difficulty distinct species disuse divergence domestic animals doubt effects eggs existing extinct extremely facts favourable fertilised fertility fishes flowers formation forms Fritz Müller genera genus geological gradations greater number groups habits Hence hybrids important increase individuals inhabitants inherited insects instance instincts intercrossing intermediate islands kind lamellæ larvæ less living males mammals manner marsupial Mivart modified descendants natural selection naturalists nearly offspring organisation organs Origin of Species parent peculiar perfect period pigeons pistil pollen pollen-grains present preserved principle probably produced progenitor quadrupeds ranked remarked resemble rudimentary seeds sexual sexual selection slight South America stamens sterility structure struggle supposed swimbladder tend tendency theory tion trees variability variations varieties vary whilst whole widely wings young