The cultivation of senna is carried on to considerable extent in Ethiopia, Arabia, Persia, and Upper Egypt, from several of which countries it has, from time immemorial, been brought by the caravans to Alexandria, as the most convenient port whence it could be shipped or sold into Europe. From this circumstance, it is sometimes denominated _Alexandrian senna_. The process of stripping and drying the leaves is perfectly simple. When dried, they are of a yellowish green colour, have a faint, though not unpleasant smell, and a somewhat acrid, bitterish, and nauseous taste. These leaves have long been in use in Eastern countries as a medicine; and their repute, though not so great as in the East, is very considerable in Europe. They are administered in various ways; and the _pods_ have the same effect as the leaves. A kind of senna has of late been cultivated, with success, in Italy and some of the southern parts of France. 137. _The OFFICINAL CASSIA is a somewhat cylindrical pod, about an inch in diameter, and a foot or more in length, the fruit of a tree_ (Cassia fistula) _which is cultivated in Egypt, the East and West Indies, and South America._ _This tree is forty or fifty feet high, and much branched. Its leaves are winged, with five pair of leaflets, somewhat oval, pointed, smooth, and of pale green colour. The flowers are large, yellow, and grow in oblong clusters. The pods are divided, by transverse partitions, into numerous cells, each containing one seed._ These pods are in request on account of the black, sweetish, but somewhat acid _pulp_, which is contained in their cells, and which is used, in many cases, as a mild opening medicine. It is customary in Egypt to pluck the pods before they are quite ripe, and to place them in a house, from which the external air is, as much as possible, excluded. They are then laid in beds about six inches deep, having palm leaves interposed betwixt them. On the two following days the whole are sprinkled with water; and, in the course of about six weeks, they are in a fit state to be packed for sale. The East Indian and West Indian cassia somewhat differ, both in appearance and qualities. Of the former the pods are smoother, smaller, and have a thinner rind; and the pulp is of a deeper shining black colour, sweeter, and more agreeable to the taste. In choosing cassia, those pods should be selected which are the heaviest, and in which the seeds do not rattle on being shaken. 138. _LIGNUM VITÆ and GUIACUM are the wood and resin of a large West Indian tree_ (Guiacum officinale, Fig. 77) _which has winged leaves in two sets upon one footstalk, and regular flowers of five petals._