| → to the various 1869 1872 |
| various 1859 1860 1861 1866 |
|
| → a single birthplace is the 1869 1872 |
| this has been the universal 1859 1860 1861 1866 |
|
|
occur, in which we cannot explain how the same species could have passed from one point to the other. But the geographical and climatal changes, which have certainly occurred within recent geological times, must have
rendered discontinuous the
continuous range of many species. So that we are reduced to consider whether the exceptions to continuity of range are so numerous and of so grave a nature, that we ought to give up the belief, rendered probable by general considerations, that each species has been produced within one area, and has migrated thence as far as it could. It would be hopelessly tedious to discuss all the exceptional cases of the same species, now living at distant and separated
nor do I for a moment pretend that any explanation could be offered of many
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
productions; and thirdly, the occurrence of the same terrestrial species on islands and on the
though separated by hundreds of miles of open sea. If the existence of the same species at distant and isolated points of the
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 climatal and geographical changes and
→to the various
occasional means of transport, the belief that
→a single birthplace is the
law, seems to me incomparably the safest. |
|
| In discussing this subject, we shall be enabled at the same time to consider a point equally important for us, namely, whether the several
species of a genus,
|
