familiar with it by practical microscopical study of leaves. For a teacher
to endeavor to explain the complex structure of the leaf, without having
seen it for himself, is open to the same objection which could be urged
against the attempted explanation of complicated machinery by one who has
never seen it, but has heard about it. What is here said with regard to
stomata applies to all the more recondite matters connected with plant
structure."[1]

[Footnote 1: Concerning a few Common Plants, p. 29.]

There are many simple experiments which can be used to illustrate the
subject.

(1) Pass the stem of a cutting through a cork, fitting tightly into the
neck of a bottle of water. Make the cork perfectly air-tight by coating it
with beeswax or paraffine. The level of the liquid in the bottle will be
lowered by the escape of water through the stem and leaves of the cutting
into the atmosphere.

(2) Cut two shoots of any plant, leave one on the table and place the
other in a glass of water.[1] The first will soon wilt, while the other
will remain fresh. If the latter shoot be a cutting from some plant that
will root in water, such as Ivy, it will not fade at all. Also, leave one
of the plants in the schoolroom unwatered for a day or two, till it begins
to wilt. If the plant be now thoroughly watered, it will recover and the
leaves will resume their normal appearance.

[Footnote 1: Lessons in Elementary Botany, by Daniel Oliver, London.
Macmillan & Co., 1864, pp. 14-15.]