The Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for Life, 2권

accumulated adapted admit adult affinity allied species ancient animals appear Archipelago arctic areas become beds believe birds breeds Cambrian changes characters classification climate closely allied continent crustaceans degree deposited difficulty distant distinct species domestic doubt embryo Europe existing extinct fact faunas fertilised fertility flowers formations formerly forms fossil fresh-water Fritz Müller Gärtner genera genus geological period geological record Glacial period groups of species habits hybrids hybrids produced important individuals inhabitants inherited insects instance intermediate intervals land larvæ less living mammals manner marine Marsupials migration modified descendants mongrels mountains natural selection naturalists nearly occur oceanic islands offspring organisation parent parent-form peculiar perfect pistil plants pollen present probably produced quadrupeds reciprocal crosses regions remains remarked reproductive resemblance rocks rudimentary organs seeds Silurian slight South America species belonging stage stamens sterility structure successive suppose terrestrial tertiary tion variations varieties whilst widely different wings