sugar maple trees, turpentine from pine, tannin from oak bark, Peruvian bark from cinchona, are all useful products.
Suggestions.—Parts of a root and stem through which liquids rise. 49. Pull up a small plant with abundant leaves, cut off the
root so as to leave two inches or more on the plant (or cut a leafy
shoot of squash or other strong-growing coarse plant), and stand it
in a bottle with a little water in the bottom which has been colored
with red ink (eosin). After three hours examine the root; make
cross-sections at several places. Has the water colored the axis
cylinder? The cortex? What is your conclusion? Stand some
cut flowers or a leafy plant with cut stem in the same solution and
examine as before: conclusion? 50. Girdle a twig of a rapidly
growing bush (as willow) in early spring when growth begins (a)
by very carefully removing only the bark, and (b) by cutting away
also the sapwood. Under which condition do the leaves wilt?
Why? 51. Stand twigs of willow in water; after roots have formed
under the water, girdle the twig (in the two ways) above the roots.
What happens to the roots, and why? 52. Observe the swellings
on trees that have been girdled or very badly injured by wires or
otherwise: where are these swellings, and why? 53. Kinds of wood. Let each pupil determine the kind of wood in the desk,
the floor, the door and window casings, the doors themselves, the
sash, the shingles, the fence, and in the small implements and
furniture in the room; also what is the cheapest and the most
expensive lumber in the community. 54. How many kinds of
wood does the pupil know, and what are their chief uses?
Note to Teacher.—The work in this chapter is intended to be mainly descriptive, for the purpose of giving the pupil a rational conception of the main vital processes associated with the stem, in such a way that he may translate it into his daily thought. It is not intended to give advice for the use of the compound microscope. If the pupil is led to make a careful study of the text, drawings, and photographs on the preceding and the following pages, he will obtain some of the benefit of studying microscope sections without being forced to spend time in mastering microscope technique. If the school is equipped with compound microscopes, a teacher is probably chosen who has the necessary skill to manipulate them and the knowledge of anatomy and physiology that goes naturally with such work; and it would be useless to give instruction in such work in a text of this kind. The writer is of the opinion that the introduction of the compound microscope into first courses in botany has been productive of harm. Good and vital teaching demands first that the pupil have a normal,
