Evolution by Natural Selection

1st ed 6th ed abortive organs acquired adapted admit affinity allied analogous appear become believe birds breed cattle cause changes chapter characters Charles Darwin climate common common descent continent corresponding crossing Crustacea Darwin degree descended distinct distribution dogs domestic animals domestic races doubt E. B. Ford effect embryo evidence evolution existence external conditions extinct facts favourable fertile forms fossil Francis Darwin Galapagos gene genera genus geological germinal vesicle groups H. J. Muller habits hereditary hybrids increase individuals inhabitants inherited instance instincts intermediate islands less Letters Lyell main divisions mammifers marsupial modified mountains natural selection naturalists Note in original occurs offspring Origin of Species parent passage peculiar period plants preserved probably produced quadrupeds reproductive resemblance seeds sheep shown similar Sketch of 1842 slight South America species sterility structure struggle suppose tend tendency theory tion unity of type variation varieties vary wild young