This colossus of the vegetable world was discovered in Senegal by the French botanist Adanson, in 1749. He measured the trunks of several individuals, and found them from 65 to 78 feet in circumference, with mighty branches, each of which was equal to a great oak or magnificent chestnut. One baobab he computed at 90 feet in girth, and its rounded crest extended over an area of upwards of 170 yards in circuit. A root which was exposed to view, through the washing away of the superjacent soil, measured 110 feet in length. Adanson estimated the age of some of these Anakim of trees at 1500 years. They were just shooting above the ground, if this reckoning be true, at the time that Constantine, the first Christian emperor, removed the seat of empire from Rome to Constantinople. There are other gigantic trees in the forests of Senegambia, as, for instance, the _Khaya Senegalensis_, which rears its crest to a height of 50 or 60 yards, whose hard reddish-coloured timber belongs to the species known in commerce under the name of _Mahogany_. Another kind of mahogany, but less valuable, called Senegal Mahogany, is furnished by the _Swietenia Senegalensis_ (family of _Meliaceæ_, tribe of _Cedrelaceæ_), named after Baron von Swieten, a Dutch botanist. It forms a stately tree, some 60 or 80 feet high. _Swietenia Mahogani_, a native of the warmer regions of America and the West Indies, yields the mahogany of commerce. The first discovery of the existence of this kind of wood is ascribed to the carpenter on board Sir Walter Raleigh's vessel, when lying off Trinidad in 1595. It is not considered to reach perfection under the venerable age of two hundred years. The seeds prepared with oil are used by the modern Mexicans, as they were by the ancient Aztecs, for cosmetic purposes; and the bark is considered a febrifuge. Among the most curious trees of the Senegal, whose Flora has quite a character of its own, travellers have singled out the Butter Tree (_Bassia butyracea_, family of the _Sapotaceæ_), whose fruits contain an edible fatty substance, used by the natives as a substitute for butter; and the Henna (_Lawsonia inermis_), which also flourishes on the eastern coast and in Upper Egypt. The henna is a shrub from six to seven feet high. Its flowers exhale a goat-like odour, which seems much affected by the Orientals and the natives of Africa. Its roots, of a deep red hue, are distinguished by a bitter taste and astringent properties. Finally, its leaves supply an orange-red colouring matter, with which the Arabs and negroes tint their hair, beard, and nails. Let us not pass over without the tribute of our respectful notice the numerous tribe of Acacias, which form vast forests in the districts north of the Senegal, and yield the gum-arabic of commerce. The best known species of this important and useful group are the _Acacia Arabica_, or Red Gum-tree, the _Acacia Adansoni_, the _Acacia vera_, and the _Acacia verek_.