carried on.
"Physiologically, leaves are green expansions borne by the stern,
outspread in the air and light, in which assimilation and the processes
connected with it are carried on."[1]

[Footnote 1: Gray's Structural Botany, p. 85.]

The whole leaf is covered with a delicate skin, or epidermis, continuous
with that of the stem.[1]

[Footnote 1: Reader in Botany. XI. Protection of Leaves from the Attacks
of Animals.]

2. _Descriptions_.--As yet the pupils have had no practice in writing
technical descriptions. This sort of work may be begun when they come to
the study of leaves. In winter a collection of pressed specimens will be
useful. Do not attach importance to the memorizing of terms. Let them be
looked up as they are needed, and they will become fixed by practice. The
pupils may fill out such schedules as the following with any leaves that
are at hand.

SCHEDULE FOR LEAVES.

Arrangement _Alternate_[1]

|Simple or compound. _Simple_
|(arr. and no. of leaflets)
|
|Venation _Netted and
| feather-veined_
|Shape _Oval_
1. BLADE <
| Apex _Acute_
|
| Base _Oblique_
|
|Margin _Slightly wavy_
|
|Surface _Smooth_

2. PETIOLE _Short; hairy_

3. STIPULES _Deciduous_

Remarks. Veins prominent and very straight.

[Footnote 1: The specimen described is a leaf of Copper Beech.]

In describing shapes, etc., the pupils can find the terms in the book as
they need them. It is desirable at first to give leaves that are easily
matched with the terms, keeping those which need compound words, such as
lance-ovate, etc., to come later. The pupils are more interested if they
are allowed to press and keep the specimens they have described. It is not
well to put the pressed leaves in their note books, as it is difficult to
write in the books without spoiling the specimens. It is better to mount
the specimens on white paper, keeping these sheets in brown paper covers.
The pupils can make illustrations for themselves by sorting leaves
according to the shapes, outlines, etc., and mounting them.