xiv Preliminary Observations. 
introduced by their names, and some few remarks on their properties, 
into the works already noticed ; and to enable every one to identify 
the precise plants described, good coloured engravings of them are 
indispensable. : 
_ The author of the following pages has undertaken the task of 
“WR drawing and describing all the important plants of a medicinal cha- 
racter, native to the United States, which are known; and also of 
figuring and describing many never before noticed for medical pro- 
perties. In all the drawings, many of which are already finished, 
the greatest accuracy will be studied ; and with a view to render the 
work | as. correct as possible, the author encounters the laborious 
task of colouring all the plates with his own hand. Since faithful 
colouring is nearly as important in a work of this nature, as correct 
- drawitigs, he trusts that the usefulness of the undertaking will be 
enhanced by this part of his labour. In the history of the plants no- 
thing will be omitted, which can render the work interesting. 
Three years have been passed in collecting materials for this 
work, The author has already delivered three courses of public lec- 
tures to the medical students of the University of Pennsylvania, on 
the plants which will be described ; and he announced to the mem- 
bers of his class, in May, 18416, his intention of publishing the system 
of Indigenous Vegetable Materia Medica, of which he now presents 
the first number. - | : 
