ut only when the sun
is shining. They are visited by numerous insects which carry the
pollen from one flower to another and deposit it upon the stigma,
where it germinates, and the tube, growing down through the long
style, finally reaches the ovules and fertilizes them. Usually only a
comparatively small number of the seeds mature, there being almost
always a number of imperfect ones in each pod. The pod or fruit (_F_)
is full-grown about a month after the flower opens, and finally
separates into three parts, and discharges the seeds. These are quite
large (Fig. 81, _J_) and covered with a yellowish brown outer coat,
and provided with a peculiar, whitish, spongy appendage attaching it
to the placenta. A longitudinal section of a ripe seed (_K_) shows the
very small, nearly triangular embryo (_em._), while the rest of the
cavity of the seed is filled with a white, starch-bearing tissue, the
endosperm.

[Illustration: FIG. 82.--_Erythronium_. _A_, a portion of the wall of
the anther, x 150. _B_, a single epidermal cell from the petal, x 150.
_C_, cross-section of a fibro-vascular bundle of the stem, x 150.
_tr._ vessels. _D_, _E_, longitudinal section of the same, showing the
markings of the vessels, x 150. _F_, a bit of the epidermis from the
lower surface of a leaf, showing the breathing pores, x 50. _G_, a
single breathing pore, x 200. _H_, cross-section of a leaf, x 50.
_st._ a breathing pore. _m_, the mesophyll. _fb._ a vein. _I_,
cross-section of a breathing pore, x 200. _J_, young embryo, x 150.]

A microscopical examination of the tissues of the plant shows them
to be comparatively simple, this being especially the case with the
fibro-vascular system.

The epidermis of the leaf is readily removed, and examination shows
it to be made up of oblong cells with large breathing pores in
rows. The breathing pores are much larger than any we have yet
seen, and are of the type common to most angiosperms. The ordinary
epidermal cells are quite destitute of chlorophyll, but the two
cells (guard cells) enclosing the breathing pore contain numerous
chloroplasts, and the oblong nuclei of these cells are usually
conspicuous (Fig. 82, _G_). By placing a piece of the leaf between
pieces of pith, and making a number of thin cross-sections at right
angles to the longer axis of the leaf, some of the breathing pores
will probably be cut across, and their structure may be then better
understood. Such