At this favorable season the wild animals—the lion, the gazelle, and the antelope—wander to the sections in the south. Here nature provides the nourishment which the dry summer season could not afford them.
In the southern portions of the Sahara, and in some more northern sections, the tropical rains produce periodical changes in the character of the desert. Under the influence of these rains, the sandy plains soon become clothed with grasses and shrubs.
During the dry season this carpet of green disappears, and the country becomes again an arid tract. Stubbles and tufts of mimosas are the only signs of vegetable life.
The beneficial change from the dry to the rainy season does not always take place. The tropical rains frequently fail to make their appearance in these northern sections, and the hopes of the desert, thirsting for moisture, are doomed to disappointment.
CHAPTER III.
THE OASES OF THE DESERT.
This desolation of the Sahara would be of such a nature that nothing, either in the animal or vegetable world, could survive, were it not for the fertile tracts, or oases, found at intervals throughout its whole extent.
These oases, or roadies, as they are sometimes called, are caused by subterranean, or underground, springs. Oases are more common in the eastern part of the Sahara than in the other sections.
