ON CINCHONA. 
253 
their presence on Cinchona bark is a bad characteristic. 
Very few, however, are met with. 
Quilling of the bark. — Bark, little or not at all curled, is 
called in commerce flat bark {Cinchona plana.) The ab- 
sence of the curl arises from one of two circumstances, — the 
age of the stem from which the bark is taken, or the want of 
flexibility of the bark even in the fresh state. When bark is 
rolled eylindrically in a quilled form, it is termed quilled 
bark {Cinchona tubulata.) Bergen speaks of several kinds 
of quilling — namely, the partially quilled {Cinchona sub- 
eonvoluta,) when the two edges of the quill approximate, — 
the closely quilled {Cinchona convoluta,) when the edges of 
the quill overlap each other, forming a more or less closely 
rolled up tube, — and the doubly quilled {Cinchona involuta) 
when both edges of the quill are rolled together, so as to form 
two cylinders, but which, seen from the back, appears as one. 
Fracture. — The transverse fracture of bark furnishes an 
important character. Bergen admits three kinds of it: 1st. 
smooth, even, or short fracture {fractura plana;) 2dly, resin- 
ous fracture {fractura resinosa;) and 3dly, fibrous fracture, 
{fractura fibrosa.) Bark with a resinous fracture is usually 
to be preferred. 
Color, taste, and smell. — Little need be said of these cha- 
racters. The same kind of bark often varies in its color, 
while several kinds may have the same tint. Moisture usually 
deepens the color. 
Classifications and varieties of Cinchona barks. — A bo- 
tanical classification of the Cinchona barks I hold to be at 
present impracticable; and moreover, if it were practicable, it 
would be, in a commercial and pharmaceutical point of view, 
useless, since the barks are never accompanied by the other 
parts of the tree from which the botanical characters are drawn. 
A chemical classification I also think cannot be at present 
attempted with any great chance of success. Goebel has 
offered the following: — 
