40 CINCHONA BARKS. 
still living layers, small starch granules. The same are also found 
in the parenchyma of the bark itself, although not very abundantly. 
The outermost layers of young barks contain, moreover, also 
chlorophyll granules. 
The already mentioned, extremely small and slightly developed 
crystals of calcium oxalate, are deposited here and there in the 
parenchyma of the true Cinchonas, so that all the cells containing 
crystals by no means possess lignified or even only thickened 
walls; the stone-cells enclosing oxalate are altogether of even less 
frequent occurrence. Larger, often well developed crystals, are 
contained in the barks of those trees which are related to the Cin- 
chonas, as in the Cinchona cuprea, and, as it appears, also usually 
in greater abundance. In others, vertical rows of cells containing 
crystals are found in the bast, while in the Cinchona barks these 
only occur isolated. 
In addition to these universally distributed substances, the 
peculiar constituents of the Cinchona barks do not admit of direct 
observation by means of the microscope. 
Oudemans (Aanteekeningen, etc., of the Pharmacopoeia Neerlan-. 
dica, 1854 to 1856, p. 221) had already observed the occurrence 
of crystals in Cinchona Calisaya and Cinchona rubra, Howard, in 
1862, in the Nueva Quinologia of Pavon (Plate II of the micro- 
scopic figures), and in 1870, in the first part of the “East Indian 
Plantations,” figured crystals which exhibit themselves in the paren- 
chyma of Cinchona barks when thin sections of the same are 
warmed for a moment with caustic alkali, and the latter removed 
as speedily as possible. Howard declares these crystals to be the 
chinovates of the cinchona bases, and considers that they are already 
deposited in a crystalline form’ in the respective barks, as, for 
instance, in Ledger’s Calisaya bark, where these crystals are said 
to be already visible without further treatment of the section. By 
the examination of a bark kindly furnished me by Howard, I was 
unable to convince myself that such crystals were originally present 
therein; they presumably consist of the alkaloids which have been 
liberated by the action of the alkali. 
Through my investigation, as also that of Miller, it is known 
that the alkaloids are located in the parenchyma of the Cinchona 
barks and not in the bast-fibres. Carles* has likewise confirmed 
these observations. 
* Kerner finds the chinovates of the cinchona bases to be uncrystallizable. 
? Wiggers-Husemann’s Fahresbericht der Pharmako oste, etc., 1866, p. 82; 
Quinology of the East Indian Plantations, 1869, p. 33. i i 1 eps eles 
* In Pringsheim’s Fahrbiicher Sir wissenschaftliche Botanik, 1866, p. 238. 
* Fournal de Pharmacie, 16, (1873), p. 22. 
