Maggiore, indeed, least fortunate of the three main sheets, is being attacked by the insidious foe at three points simultaneously. At the upper end, the Ticino, that furious radical river, has filled in a large arm, which once spread far away up the valley towards Bellinzona. A little lower down, the Maggia near Locarno carries in a fresh contribution of mud, which forms another fan-shaped delta, and stretches its ugly mass half across the lake, compelling the steamers to make a considerable detour eastward. This delta is rapidly extending into the open water, and will in time fill in the whole remaining space from bank to bank, cutting off the upper end of the lake about Locarno from the main basin by a partition of lowland. This upper end will then form a separate minor lake, and the Ticino will flow out of it across the intervening mud flat into the new and smaller Maggiore of our great-great-grandchildren. If you doubt it, look what the torrent of the Toce, the third assailing battalion of the persistent mud force, has already done in the neighbourhood of Pallanza. It has entirely cut off the upper end of the bay, that turns westward towards the Simplon, by a partition of mud; and this isolated upper bit forms now in our own day a separate lake, the Lago di Mergozzo, divided from the main sheet by an uninteresting mud bank. In process of time, no doubt, the whole of Maggiore will be similarly filled in by the advancing mud sheet, and will become a level alluvial plain, surrounded by mountains, and greatly admired by the astute Piedmontese cultivator. What is going on in Maggiore is going on equally in all the other sub-Alpine lakes of the Po valley. They are being gradually filled in, every one of them, by the aggressive mud sheet. The upper end of Lugano, for example, has already been cut off, as the Lago del Piano, from the main body; and the _piano_ itself, from which the little isolated tarn takes its name, is the alluvial mud fiat of a lateral torrent--the mud flat, in fact, which the railway from Porlezza traverses for twenty minutes before it begins its steep and picturesque climb by successive zigzags over the mountains to Menaggio. Similarly the influx of the Adda at the upper end of Como has cut off the Lago di Mezzola from the main lake, and has formed the alluvial level that stretches so drearily all around Colico. Slowly the mud fiend encroaches everywhere on the lakes; and if you look for him when you go, there you can see him actually at work every spring under your very eyes, piling up fresh banks and deltas with alarming industry, and preparing (in a few hundred thousand years) to ruin the tourist trade of Cadenabbia and Bellagio.