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, 
