one, and it is best, even with the older pupils, to touch it lightly. The
point to be especially brought out is the disposition of the leaves so
that each can get the benefit of the light. This can be seen in any plant
and there are many ways in which the desired result is brought about. The
chief way is the distribution of the leaves about the stem, and this is
well studied from the leaf-scars.

The scholars should keep the branches they have studied. It is well to
have them marked with the respective names, that the teacher may examine
and return them without fear of mistakes.

In the various branches that the pupils have studied, they have seen that
the arrangement of the leaves differs greatly. The arrangement of leaves
is usually classed under three modes: the _alternate_, the _opposite_,
and the _whorled_; but the opposite is the simplest form of the whorled
arrangement, the leaves being in circles of two. In this arrangement, the
leaves of each whorl stand over the spaces of the whorl just below. The
pupils have observed and noted this in Horsechestnut and Lilac. In these
there are four vertical rows or ranks of leaves. In whorls of three leaves
there would be six ranks, in whorls of four, eight, and so on.

When the leaves are alternate, or single at each node of the stem, they
are arranged in many different ways. Ask the pupils to look at all the
branches with alternate leaves that they have studied, and determine in
each case what leaves stand directly over each other. That is, beginning
with any leaf, count the number of leaves passed on the stem, till one is
reached that stands directly over the first.[1] In the Beech and the Elm
the leaves are on opposite sides of the stem, so that the third stands
directly over the first. This makes two vertical ranks, or rows, of
leaves, dividing the circle into halves. It is, therefore, called the