Geographical Distribution. 209 
one time the species occupied the whole of the range 
in question, but afterwards became broken up as 
geographical, climatic, or other changes rendered 
parts of the area unfit for the species to inhabit. 
Thus, for instance, it is easy to understand that 
during the last cold epoch the mountain-hare would 
have had a continuous range; but that as the Arctic 
climate gradually receded to polar regions, the species 
would be able to survive in southern latitudes only 
on mountain ranges, and thus would become broken 
up into many discontinuous patches, corresponding 
with these ranges. In the same way we can explain 
the occurrence of Arctic vegetation on the Alps and 
Pyrenees—namely, as left behind by the retreat of 
the Arctic climate at the close of the glacial period. 
But now, on the other hand, the theory of special 
creation cannot so well afford to render this obvious 
explanation of discontinuity. In the case of the 
Arctic flora of the Alps, for instance, although it is 
true that much of this vegetation is of an Arctic type, 
it is not true that the species are all identical with 
those which occur in the Arctic regions. Therefore 
the theory of special creation would here have to 
assume that, although the now common species were 
left behind on the Alps by the retreat of glaciation 
northwards, the peculiar Alpine species were after- 
wards created separately upon the Alps, and yet 
created with such close affinities to the pre-existing 
species as to be included with them under the same 
genera. Looking to the absurdity of this supposition, 
as well as of others which I need not wait to mention, 
certain advocates of special creation have sought to 
take refuge in another hypothesis—namely, that 
2k P 
