Ball is of opinion (p. 584) that the effects
of the Glacial period have been greatly overrated. "Even during the
period of maximum cold the highest ridges of the Alps were not
completely covered with snow and ice; for we still see by the appearance
of the surface, the limit above which the ancient ice did not reach, and
in the middle zone the slopes that rose above the ancient glaciers had a
summer climate not very different from that which now prevails. In my
opinion the effect of the Glacial period on the growth of plants in the
Alps was to lower the vertical height of the zones of vegetation by
from one to two thousand feet." He acknowledges that there was probably
a moderate diminution of the mean temperature of Europe with an
increased snowfall, so as to cause a great extension of glaciers on all
the mountains of Northern Europe. "But that the climate of Middle Europe
was such that the plants of the high Alps could spread across the plains
seems to me an improbable supposition" (p. 584).

On the Continent, also, some botanists seem to feel that Forbes's
theories of the origin of the Alpine flora, which were at first hailed
with such delight, and accepted by almost every naturalist as the final
verdict, must be modified in the light of recent researches. Professor
Krasan believes that many plants which now live in the high Alps
flourished in pliocene times at sea-level (p. 37). "Especially the
evergreen species exhibit the impression of an originally mild
climate--of a climate without winter frosts--for otherwise the plants
would have developed into species with deciduous leaves." To the
favourable conditions, consisting in periodic snowfalls and high summer
temperature, must be attributed the fact that in the highlands so many
more species from Tertiary times have survived than in the plains. The
temperature was probably much higher during the Glacial period than is
generally believed. The climate was more moist, thus contributing to an
abundant snowfall, while the survivors of ancient Tertiary times were
able to repeople the parts which were temporarily devastated by the
advancing glaciers.

In so short a chapter it is impossible to deal with the Alpine fauna in
a manner more deserving of this theme. I have merely sought to give a
sketch of the general outlines of the subject and to suggest another
possible mode of origin of Alpine animals than that currently believed
in by naturalists. It is to be hoped these s