256 
SELECTED ARTICLES. 
known in French and English commerce. Lectures, how- 
ever, are not adapted for entering into an account of all the 
known varieties, and, therefore, I shall confine myself princi- 
pally to those commonly used in medicine"! in this country, 
only introducing an account of others when they serve to 
illustrate the history of the more important ones. I shall 
adopt the following arrangement: — 
Div. I. — Genuine Cinchona Barks. 
Section 1. — Having a brown epidermis. 
(a.) Pale barks. 
(b.) Yellow barks, 
(c.) Red barks. 
(d.) Brown barks. 
Section 2. — Having a whitish epidermis, (white Cinchona 
of some authors.) 
(a.) Pale. 
(b.) Yellow, 
(c.) Red. 
Div. II. — False Cichona barks. 
Div. I. — True Cinchona Barks. 
By the terms true, or genuine Cinchona bark, (Cinchona 
vera,) I mean the bark of some species of the genus Cinchona. 
Hitherto all these barks have been found to contain one or 
more of the vegetable alkalies, quinia, cinchonia, or aricina: 
we presume, therefore, one or more of these to be essential, 
and perhaps we might also add peculiar, to the genus. 
The true Cinchonas are subdivided from the character of 
their epidermis. In some Cinchona barks, (the Carthagena, 
for example,) the epidermis is naturally white, has a mica- 
ceous appearance, is smooth, not cracked, and adheres to the 
subjacent laminae: these are the white Cinchonas of some 
continental writers, (Guibourt, for example.) In other in- 
stances the epidermis is naturally more or less brown, crack- 
ed, and rugous. Frequently, however, it has a whitish 
