The roots of the scammony plant are thick, black on the surface, white within, and full of an acrid milky juice, which, in a concrete state, is frequently used in medicine. To obtain it, the earth, at a certain season of the year, is removed from the upper part of the roots whilst they are growing, and the tops are cut obliquely. The juice flows from the wound into a small vessel sunk into the earth, at the lower end of the gash, to receive it. But, as each root furnishes only a very small quantity, the produce of several roots is usually mixed together for the greater convenience of being exposed to the sun and dried. Still, however, the quantity, thus obtained, is sometimes insufficient to supply the demand. In this case an addition is made to it by the pressure of juice from the leaves and stalks. The best scammony is imported from Aleppo, in light, spongy, friable pieces, of shining blackish grey colour, which have a faint, unpleasant smell, and a bitterish, pungent taste. It is sometimes adulterated with flour, and sometimes even with sand or earth. In its medical effects, scammony, when administered alone, is an efficacious, though violent purgative. But if triturated or ground down with sugar, almonds, or gum-arabic, its operation becomes sufficiently mild and safe. 61. _JALAP is a dark-coloured root, which is usually imported, in transverse slices, from South America._ _The plant that produces it_ (Convolvulus jalapa, Fig. 8) _belongs to the convolvulus tribe, and has generally somewhat heart-shaped leaves, and flowers that are reddish on the outside, and dark purple or yellowish within._ The name of jalap is derived from Xalapa, a town in South America, situated betwixt Vera Cruz and Mexico, where the plant, of which it is the root, was originally discovered, and whence it has been imported, in great quantities, into Europe. The jalap plant is now cultivated in the botanical garden at Charlestown, and in several other parts of America. When recent, the root is large, whitish, and full of juice; but, when dried, the best pieces are compact, hard, weighty, and of dark colour, with black circular marks. Both in smell and taste it is very nauseous. It is frequently mixed with slices of bryony root; but these are easily distinguished by their paler colour and porous texture. The only mode in which this root is of use is as a medicine; and it is administered in substance, in a tincture, and an extract. It has been advantageously employed in several disorders; but, as it is very powerful in its effects, great caution is necessary in the use of it, particularly with children. 62. _PERUVIAN BARK is the produce of a tree which grows in South America, and chiefly in Peru, whence its name has been derived._