Fig. 327. Transverse section of the very young bark

of Cinchona ovata, showing the disposition of the layers before their modification by the progress of vegetation.
ep, Remains of the epidermis.
s', Suberous coat or resinous circle.
ec, Cellular envelop.
la, Lacunae: these, as well as the cells of the cellular envelop, are filled with resinous matters, which require to be removed in order to render the cell-walls obvious.
l, Liber.
fl', Cortical fibres.

This image is from _ in Pereira's Elements of Materia Medica and Therapeutics, 1854.