Leaving the last dwellings of the Nueir behind us, we arrived on the following day at the first wood which is to be observed on the banks of the Gazelle. Ant-hills of more than ten feet high are here scattered in every direction, and alone break the universal levelness of the plain. They are not unfrequently found in the heart of a thicket, because originally the stem of a tree served as the central axis of the earthy structure. Dead and withered though this had been, it sprouted out afresh from the roots, provided that these had been uninjured by the passages of the ants. Vestiges of the floods are traceable upon them, and show that the average difference between the highest and lowest level of the water is from three to four feet. [Sidenote: ALONG THE GAZELLE.] The river wends its way through charming wood-scenery, meandering amidst groves gay with the red bindweed (_Ipomæa_), amidst which now and then a tall tamarind uprears itself. Here I met with a fresh representative of the flora of Central Africa in the tree-like Euphorbia with its arms outspread like candelabras. This can be distinguished from the Euphorbia of the Abyssinian highlands, mentioned in Chapter I., by the involved confusion of its branches. Its eccentric shapes would seem to fill a place in Africa which in America is supplied by the order of the Cactaceæ; it also serves like the Mexican Cereus for the enclosure of estates, as slips taken from its branches readily take root in the ground. The sportsman could here reckon on a good bag, for the widow-ducks which swarmed upon the papyrus were brought down at every shot, and were serviceable for the table. Our people were all expert swimmers, and they continually fished out of the stream the birds which were struck, while their sport in no way ever hindered the progress of our craft.