LULU-TREES. 173 all along the road were large quantities of ironstone, and we passed almost continuously under huge lulu-trees. This tree, which grows in vast quantities throughout the Bahr-el-Ghazel Province, forming forests of hundreds of square miles in extent, attains usually a height of about forty feet. It is much branched, and has a dome-shaped head of foliage. The leaves, which are very long in comparison with their breadth, grow in whorls at the extremity of the twigs ; they are of a bright sea-green colour, smooth and shining. From the centre of the leaves springs a cluster of flowers, which are small cup-shaped blossoms of a greenishyellow colour. The fruit is a nut of the size of a small walnut, but spherical in shape; it has a thin hard brown shell. The bark is very thick and somewhat corky, being seamed in all directions with cracks and fissures ; when wounded a large quantity of caoutchouc of superior quality exudes. The nut yields, when crushed and boiled, a quantity of greenish oil, which at ordinary temperatures is solid. It is used by the Bongo, Djour, and other tribes as an article of food ; but it has a strong and, to a European palate, somewhat unpleasant flavour. A sample of this " butter " we brought with us to England, and an analysis of it will be found at the end of the book. It would, I think, make a good machine grease.

The river Djour was 200 yards broad, and very