As we travel to the north-west also, with the increase in the rainfall and the consequent increase in pasturage, the number of cattle increases, and with them the increased use of beef as food, and the increased use of cows' milk and milk products. This is well seen in the broad fields of Normandy, while still further west, in the British Islands, pastures become more and more extensive, and only the existence of a well-marked "rain shadow" on the eastern seaboard, which is robbed of much of its rainfall by the hills of the west, makes the extensive growth of wheat possible in south-eastern England. With the increase of pasture, and the increased cold of winter, as compared with the Mediterranean area, we have stall-feeding, with the possibility of collecting manure for the fields. The consequence is that England, with a climate very different from that which wheat experiences elsewhere, has a yield per acre greater than that of any other country in the world. France, despite her warmth and sunshine, only gets an average of 19 bushels to the acre from her wheat fields, while in England, where wheat can only be grown at a profit when the conditions are especially favourable, the average yield is 30 bushels per acre. In those parts of Europe where the climate or soil does not suit cereals, even such cereals as oats and rye, there is a tendency for these to be partially replaced as the basis of the diet by plants requiring less sunshine and tolerant of greater moisture. Thus in Ireland and North Germany, the potato is a very important article of diet, while in France and in Mediterranean regions generally it is unimportant. Similarly, towards the north the "fowl in the pot" tends to be replaced by fish, in the case of those who cannot afford beef or mutton. In the more northern regions also, with their relatively large rainfall, root crops play a very important part. Most of these are grown for the domestic animals, as turnips, mangels, swedes, etc., a phenomenon which does not occur in the Mediterranean area to any extent; but the sugar beet, whose cultivation is spreading greatly in northern and central Europe, is of course grown for its yield of sugar.