ked over with India-ink or black drawing ink. Ink
drawings are best made upon light bristol board with a hard,
smooth-finished surface.

When obtainable, the student will do best to work with freshly
gathered specimens; but as these are not always to be had when wanted,
a few words about gathering and preserving material may be of service.

Most of the lower green plants (_algae_) may be kept for a long time in
glass jars or other vessels, provided care is taken to remove all
dead specimens at first and to renew the water from time to time. They
usually thrive best in a north window where they get little or no
direct sunshine, and it is well to avoid keeping them too warm.

Numbers of the most valuable fungi--_i.e._ the lower plants that are
not green--grow spontaneously on many organic substances that are kept
warm and moist. Fresh bread kept moist and covered with a glass will
in a short time produce a varied crop of moulds, and fresh horse
manure kept in the same way serves to support a still greater number
of fungi.

Mosses, ferns, etc., can be raised with a little care, and of course
very many flowering plants are readily grown in pots.

Most of the smaller parasitic fungi (rusts, mildews, etc.) may be kept
dry for any length of time, and on moistening with a weak solution of
caustic potash will serve nearly as well as freshly gathered specimens
for most purposes.

When it is desired to preserve as perfectly as possible the more
delicate plant structures for future study, strong alcohol is the best
and most convenient preserving agent. Except for loss of color it
preserves nearly all plant tissues perfectly.

CHAPTER II.

THE CELL.

If we make a thin slice across the stem of a rapidly growing
plant,--_e.g._ geranium, begonia, celery,--mount it in water, and
examine it microscopically, it will be found to be made up of numerous
cavities or chambers separated by delicate partitions. Often these
cavities are of sufficient size to be visible to the naked eye, and
examined with a hand lens the section appears like a piece of fine
lace, each mesh being one of the chambers visible when more strongly
magnified. These chambers are known as "cells," and of them the whole
plant is built up.

[Illustration: FIG. 1.--A single cell from a hair on the stamen of the
common spiderwort (_Tradescantia_), x 150. _pr._ protoplasm; _w_, cell
wall; _n_, nucleus.]

In order to study the structure of the cell more