ALOE.—ALOES. Botanical Source and History

There are several species which furnish medicinal aloes, but the three above named are supposed to yield the principal portion, although but two are now recognized by the U. S. Pharmacopœia. The mucilaginous juice expressed from the parenchymatous tissue of the leaves has no remedial influences; but only that which is procured by incising the air-ducts of the leaves transversely, so that the juice may flow from them or, as stated by M. E. Robiquet, from the intercellular structure between them. M. Marais states that three distinct kinds of Barbadoes aloes have been found in commerce, two of which are probably obtained by simple exudations of the juice from the incised leaves, while the third is the result obtained by boiling the plant in water and evaporating. These three kinds may be distinguished from the other species of aloes by a common property they have of giving a perfect emulsion when triturated with a little cold water.