viii PREFACE, 
glove, and Opium are all of them properly placed 
by authors under the head of Narcotics. But of 
these, Tobacco is an emetic, Henbane a cathartic, 
Foxglove a diuretic, and Opium, while it checks 
all other excretions, is itself sudorific. Mercury, 
under its different forms and modes of adminis- 
tration, is capable of fulfilling half a dozen differ- 
ent intentions. The classifier of medicines then 
can do no more than to arrange them by their 
most obvious and well known properties, whatever 
these may be, leaving it understood that the 
name of a class is by no means fully descriptive 
of the character of its contents. = | 
In forming a selection of sixty plants to be 
represented in this work, it has been endeavoured 
to choose those which are among the most 
interesting to botanists, at the same time that 
they possess claims upon the attention of medi- 
eal men. Itis by no means ‘to be asserted that 
all these possess so decided an efficacy as to enti- 
tle them to the rank of standard medicines, or to 
make it advisable that pharmacopeias should be 
swelled by their introduction, A part of them 
no doubt are eminently entitled to this distinction, 
Others are efficacious only in a second degree, 
* For a botanical arrangement of the plants, see the systematic 
index at the end of the volume. 
