On the 13th the slaves destined to this labour set off under the direction of several marabouts; it was not till some days afterwards that I learnt from my host’s wife the particulars which I am now about to relate. It has been believed, but without foundation, that there were forests of gum-bearing trees in the desert; travellers have fallen into this error from the inaccurate accounts of the Moors, who, to do honour to their country, always profess that every thing is to be found there in the greatest abundance. The acacia which furnishes gum grows singly in all the elevated parts of the desert, never on argillaceous or alluvial soil, but on dry sandy ground; it is very rare on the banks of the Senegal. The tree is not the same with the _mimosa gummifera_ of the botanists, which I had seen in our settlements; its leaves are regularly pinnated; the folioles are broader, thicker, and of a darker green; in its shape and appearance it more nearly resembles the acacia cultivated in France. The wells which have been dug in the interior, where the operation of collecting the gum is carried on, have given their name to the neighbourhood, and such has been the origin of the names that have been given to the fictitious gum forests. Near these wells the marabouts take up their abode, and the slaves cut straw to make huts; a single marabout superintends the slaves of his whole family, or of several of his friends; and he assembles them all, sometimes to the number of forty or fifty under the same hut. Every marabout sends as many slaves as he can spare, and they are sometimes joined by a few wretched zenagues. The superintending marabout takes with him two cows, and carries a bag of millet for his food.