Hydrographically the Ukraine is distinguished by a web of rivers concentrating in the Pontus. The Ukraine embraces the river systems of the Dniester, Boh, Dnieper, Don and Kuban—not entirely, to be sure, yet by far the greater part, leaving only the sources of the two greatest rivers to the White and Great Russians. Only the most western borderlands of the Ukraine lie within the watersheds [10]of the Baltic Rivers (the Vistula district); only the most eastern mountain-spurs in the water-shed of the Caspian Sea (Terek and Kuma). We may therefore, without hesitation, conceive of the Ukraine hydrographically as the northern part of the Eastern European water-shed. In respect to climate, the Ukraine occupies an independent position in Eastern Europe. In fact, de Martonne recently declared “the Ukrainian climate to be one of the main types of climate of the earth.” We shall not go so far as this, but we must emphasize the fact that the climate of the Ukraine differs no less from that of Poland, White Russia and Great Russia than does Germany’s climate from that of England or France. An important wind-partition crosses the Ukraine in winter from East to West, subjecting the entire southern part to the sway of the east wind. Winter in the Ukraine is strictly continental, with a coldness of 30 degrees, but not with the semi-polar character of the Russian or the Central European character of the Polish winter. The east and southeast winds by day prevent the snow-blankets, produced by the moist south winds of the Pontus, from ever becoming too heavy, especially in the Southern Ukraine, and cause them to disappear quickly in the spring. In the spring the temperature rises very rapidly. The summer of the Ukraine is the hot continental summer, and despite the predominant Atlantic west winds and the abundant precipitation, it is not sultry. Autumn is pleasant and dry. The climate of the Ukraine, then, is the continental climate of the Pontus. Toward the west it merges into the Central European climatic zone at the border of Poland, into the Eastern European continental climate at the border of White and Great Russia, into the Aralo-Caspian dry climate at the eastern border. The southern borderlands of the Ukraine, like those of France, constitute a transition to the Mediterranean climate. [11] In respect to its flora, the unique position of the Ukraine depends upon the fact that it embraces almost the entire region of the prairie-steppes of the Pontus, with their regions of transition to the Northern and Central European forest zone. Right east of the Don begin the steppes and desert-steppes of the Caspian region. Consequently, the Ukraine is the only country in Europe which has the prevailing character of the steppes. Here, again, this circumstance is of geographical importance and makes the Ukraine, in this respect also, a geographic unit.