The history of the arctic-Alpine flora of Europe is a very interesting one. These plants, whose true home is in the arctic regions, living high up on the mountains of Europe, give unmistakable evidence of a time, very far back, when Northern Europe was overrun by glaciers and snowfields so as to resemble in appearance and in climate the Greenland of the present day. This period is known to geologists as the "Great Ice Age." The moraines of glaciers, ice-worn rock surfaces, and other unmistakable signs may be well seen in many parts of Great Britain. How long ago this took place we cannot say; but judging from the considerable changes in geography which have undoubtedly taken place since then, we must conclude that many thousands of years, perhaps two hundred thousand, have intervened between this period and the present time. When arctic conditions prevailed over this wide area, the plants and animals which now live in arctic latitudes flourished in Great Britain; but as the climate gradually became more genial, and the snow and ice melted, the plants and animals mostly retreated to their northern home. A certain number doubtless became extinct; but others took to the highest parts of the mountains, where snow and ice abound; and there they remain to the present day, separated from their fellows, but still enjoying the kind of climate to which they have always been accustomed, and testifying to the wonderful changes which have taken place since the mammoth, whose bones are found embedded in our river-gravels, wandered over the plains of Northern Europe. _Animal Life._