VARIETIES OF CINCHONA BARK. 43 
The outer bark exhibits practically no stone-cells or only a few 
isolated ones, but contains a single or double circle of lacticiferous 
ducts, which, however, soon disappear. 
The bark of the Indian Calisaya Ledgeriana (see page 17), in 
consequence of its much higher percentage of alkaloid, now fur- 
nishes a complete substitute for the American bark. Many of the 
varieties formerly known as Loxa Bark, and derived from different 
Cinchonas, are especially distinguished from the bark of the twigs 
of Calisaya by the less reticulated outer surface. 
(b) The bast of the stem as Cchona (China) regia plana, 
Cinchona (China) regia sine epidermide; Flat Calisaya; Ger., 
Flache, platte, unbedeckte Konigschina; Fr., Calisaya plat. 
Flat pieces, of a foot or several feet in length, often nearly 2 
decimeters (8 inches) in width and from 5 to 15 millimeters (14 to 
54 inch) in thickness, and of that particularly handsome pure color 
which is designated as a type of the yellow varieties of Cinchona ; 
indeed, the approach to a reddish-yellow tint is often scarcely per- 
ceptible. The outer surface, by the action of the air, is frequently 
darker, at least in spots, and in consequence of the conchas (see 
page 35) more or less, often to the highest degree, irregular; the 
inner surface does not always exhibit parallel stripes, as in the 
barks of the branches, but is often wavy. In this case, the bast 
bundles of the different layers occasionally separate from the frac- 
tured surface in a diverging direction. This variety of bark is highly 
characterized by its soft tissue; even with the finger-nail one can, 
without effort, separate the pointed fibres, which readily penetrate 
the skin. 
On the edges of the conchas there are,as a rule, only a few easily 
detached bork-scales. The bast, of which, without consideration of 
the interior cork bands, the bark alone consists, displays sometimes 
more and sometimes less plainly radial, occasionally also almost 
tangential, rows of fibres. Here and there from 2 to 4 of these 
rows come in direct contact, but otherwise they always occur sepa- 
rated by the abundant parenchyma. ae 
The flat Calisaya bark from Bolivia, which until within a few 
years maintained a high character, has latterly occurred in com- 
merce with a very much diminished percentage of alkaloid. It 
was occasionally confused with the bark of a south Peruvian spe- 
cies, Cinchona scrobiculata Humboldt et Bonpland. Their uncov- — 
ered bast-plates resemble to a high degree those of the flat Cali- 
saya, but are distinguished, however, especially upon being moist-— 
1 Figure in Humb. et Bonp., Plantes éguinoct, t. 47; also Weddell’s Hist. nat. des 
Quinguinas, Plate VII. ; S 
