in fructificatione et viribus;" Petiver,an apothecary of Alders- gate-street, and well known as a botanist, has a paper in the 21st volume of the Philosophical Transactions (1699), entitled, " Some attempts to prove that herbs of the same make and class, for the generality, have the like virtue, and tendency to work the same effects.'" Again, Linna?us has stated, " Plantae quae Genere eonveniunt, etiam virtute conveniunt ; quae Ordine naturali continentur, etiam virtute proprius accedunt; quasque Classi naturali congruunt, etiam viribus quodammodo congruunt." But the progress was inconsiderable in the path pointed out by these illus- trious naturalists, until the publication by the celebrated De Candolle, who has thrown a light over so many depart- ments of Botany, of his " Essai sur les proprietes medicales des Plantes." In this work he has shown, that as the effects of the different substances used as medicines, must be owing either to their physical characters or their chemical composition, so must these depend on the peculiar organization of the vegetable, especially in the organs of nutrition, by which they are secreted. But as plants are classified from their organs of reproduction, and not from those of nutrition, it does not appear how we are led to the nature of the secretions formed by these, from a consideration of groupings founded on the examination of a different set of organs. To this it has been well replied, that though an artificial arrangement may draw its charac- ters of classes from as small a number of organs as possible, the natural method is, on the contrary, the more perfect in proportion that the characters of its classes express a greater number of ideas; hence those families which present the most numerous points of analogy in the organs of reproduc- tion, will also display them in the organs of nutrition, in which the secretions are chiefly performed. Thus the divi- sion of vegetables from the seeds, into Acotyledons,
