On The Origin of Species by Charles Darwin Chapter 12 Page 20

that any explanation could be offered of many instances. But, after some preliminary remarks, I will discuss a few of the most striking classes of facts, namely, the existence of the same species on the summits of distant mountain ranges, and at distant points in the Arctic and Antarctic regions; and secondly (in the following chapter), the wide distribution of fresh water productions; and thirdly, the occurrence of the same terrestrial species on islands and on the nearest mainland, though separated by hundreds of miles of open sea. If the existence of the same species at distant and isolated points of the earth’s surface can in many instances be explained on the view of each species having migrated from a single birthplace; then, considering our ignorance with respect to former climatical and geographical changes, and to the various