The White Nile is indebted to the Great Lakes for the greater persistence of its waters, which feed the river as far as the Mediterranean, and save the valley from utter drought in winter. But, even with this resource, the level of the water falls daily, and its volume is diminished. Long-hidden sandbanks reappear, and are again linked into continuous line. Islands expand by the rise of shingly beaches, which gradually reconnect them with each other and with the shore. Smaller branches of the river cease to flow, and form a mere network of stagnant pools and muddy ponds, which fast dry up. The main channel itself is only intermittently navigable; after March boats run aground in it, and are forced to await the return of the inundation for their release. From the middle of April to the middle of June, Egypt is only half alive, awaiting the new Nile. [Illustration: 034.jpg ASSIOUT] Those ruddy and heavily charged waters, rising and retiring with almost mathematical regularity, bring and leave the spoils of the countries they have traversed: sand from Nubia, whitish clay from the regions of the Lakes, ferruginous mud, and the various rock-formations of Abyssinia. These materials are not uniformly disseminated in the deposits; their precipitation being regulated both by their specific gravity and the velocity of the current. Flattened stones and rounded pebbles are left behind at the cataract between Syene and Keneh, while coarser particles of sand are suspended in the undercurrents and serve to raise the bed of the river, or are carried out to sea and form the sandbanks which are slowly rising at the Damietta and Rosetta mouths of the Nile. The mud and finer particles rise towards the surface, and are deposited upon the land after the opening of the dykes. Soil which is entirely dependent on the deposit of a river, and periodically invaded by it, necessarily maintains but a scanty flora; and though it is well known that, as a general rule, a flora is rich in proportion to its distance from the poles and its approach to the equator, it is also admitted that Egypt offers an exception to this rule. At the most, she has not more than a thousand species, while, with equal area, England, for instance, possesses more than fifteen hundred; and of this thousand, the greater number are not indigenous. Many of them have been brought From Central Africa by the river: birds and winds have continued the work, and man himself has contributed his part in making it more complete. From Asia he has at different times brought wheat barley the olive, the apple, the white or pink almond, and some twenty other species now acclimatized on the banks of the Nile. Marsh plants predominate in the Delta; but the papyrus, and the three varieties of blue, white, and pink lotus which once flourished there, being no longer cultivated, have now almost entirely disappeared, and reverted to their original habitats. [Illustration: 036.jpg ENTRANCE OF THE MUDIRIYEH OF ASYUT.]