wn in Fig. 333. The cells of the epicarp are broad and
polygonal, sometimes regularly four-sided, about 15-35 mu broad. At
intervals along the surface of the epicarp are stomata, or breathing
pores, surrounded by guard cells. The next layer of the pericarp is the
mesocarp (Figs. 333, 334, 335), the cells of which are larger and more
regular in outline than the epicarp. The cells of the mesocarp become as
large as 100 mu broad, but in the inner parts of the layer they become
very much flattened. Fibrovascular bundles are scattered through the
compressed cells of the mesocarp. The cell walls are thick; and large,
amorphous, brown masses are found within the cell; occasionally, large
crystals are found in the outer part of the layer. The fibro-vascular
bundles consist mainly of bast and wood fibers and vessels. The bast
fibers are as large as 1 mm long and 25 mu broad, with thick walls and
very small _lumina_. Spiral and pitted vessels are also present.

[Illustration: Fig. 334. Coffee. Surface view of _ep_, epicarp, and _p_,
outer parenchyma of mesocarp. x160. (Moeller)]

The layer next to this is a soft tissue, parenchyma (Fig. 333, 5; Fig.
334, _p_). The parenchyma, or palisade cells as they are called, is a
thin-walled tissue in which the cells are elongated, from which fact
they receive their name. The walls of these cells, though very thin, are
mucilaginous, and capable of taking up large amounts of water. They
stain well with the aniline stains.

The endocarp (Fig. 336) is closely connected with the palisade layer and
has thin-walled cells that closely resemble, in all respects, the
endocarp of the apple. The outer layer consists of thick-walled fibers,
which are remarkably porous (Fig. 333, 6; Fig. 336) while the fibers of
the inner layer are thin-walled and run in the transverse direction.

_The Bean Structure_

Spermoderm, or silver skin, is not difficult to secure for microscopic
analysis; because shreds of it remain in the groove of the berry, and
these shreds are ample for examination. It can readily be removed
without tearing, if soaked in water for a few hours. The spermoderm is
thin enough not to need sectioning. It consists of two
elements--sclerenchyma and parenchyma cells. (Figs. 333, 337, _st_,
_p_).

[Illustration: Fig. 335. Coffee. Elements of pericarp in surface view.
_p_, parenchyma; _bp_, parenchyma of fibro-vascular bundle; _b_, bast
fiber; _sp_, spiral vessel. x160. (Moeller)]

Scler