1. _The Olive region._--This region curiously illustrates what has just been said about other causes besides height influencing the climate and vegetation. For along the southern base of the Alps, the lower slopes and the mouths of the valleys have a decidedly warmer climate than the plains of Piedmont and Lombardy. Thus, while the winter climate of Milan is colder than that of Edinburgh, the olive can ripen its fruit along the skirts of the mountain region, and penetrates to a certain distance towards the interior of the chain along the lakes and the wider valleys of the Southern Alps. Even up the shores of the Lake of Garda, where the evergreen oak grows, the olive has become wild. The milder climate of the Borromean Islands, and some points on the shores of the Lago Maggiore, will permit many plants of the warmer temperate zone to grow; while at a distance of a few miles, and close to the shores of the same lake, but in positions exposed to the cold winds from the Alps, plants of the Alpine region grow freely, and no delicate perennials can survive the winter. The olive has been known to resist a temperature of about 16° F. (or 16° below the freezing point of water), but is generally destroyed by a less degree of cold. It can only be successfully cultivated where the winter frosts are neither long nor severe, where the mean temperature of winter does not fall below 42° F., and a heat of 75° F. during the day is continued through four or five months of the summer and autumn. 2. _The Vine region._--The vine, being more tolerant of cold than the olive, can grow at a higher level; and so the next zone of vegetation in the Alps may be called "the Vine region." But to give tolerable wine it requires at the season of ripening of the grape almost as much warmth as the olive needs. Vines can grow in the deeper valleys throughout a great part of the Alpine chain, and in favourable situations up to a considerable height on their northern slopes. On the south side, although the limit of perpetual snow is lower, the vine often reaches near to the foot of the greater peaks. But the fitness of a particular spot for the production of wine depends far more on the direction of the valley and of the prevailing winds than on the height. And so it happens that in the Canton Valais, the Valley of the Arc in Savoy, and some others on the north side of the dividing range, tolerable wine is made at a higher level than in the valleys of Lombardy, whose direction allows the free passage of the keen northern blasts. It is a curious fact that in the Alps the vine often resists a winter temperature which would kill it down to the roots in the low country; and we must explain it by the protection of the deep winter snow. Along with the vine many species of wild plants, especially annuals, characteristic of the flora of the south of Europe, show themselves in the valleys of the Alps.