tnote 1: Each of these books has the Professor's definitions on the
last pages.]

[Illustration: _Fig. 14. Serrate. Fig. 15. Bi-serrate._]

"If you would make drawings of the different kinds of leaves and give
their names we could hang them up and could look at them any time."

"The leaf is the proper part to commence on, because it is the most
important thing of every plant, or tree, or shrub."

"What, more important than the fruit or the flower, or the nut that
grows on the tree?"

"That is just what I mean. When you smell the rich red flower of the
rose, or look at the pure white petals of the lily, or the
sweet-smelling blossoms of the orange or the jasmine, you are simply
seeing or smelling leaves. The fruit itself, whether in the form of an
apple, or a berry or a nut, is simply a form of leaf, a perfected form
of the plant, or bush, or tree. Originally all these fruits, flowers and
nuts were but leaves in an undeveloped state."

"I never heard of such a thing before."

"It is a subject treated of in botanical knowledge which is called
Morphology, and the object is to show that every fruit and flower was
developed, in accordance with a well-known law, from the particular
shape or form of the leaf. We can go into that branch of the subject
later on. What we now want is to know something about the shape of the
leaf, so we can have a starting point. There are two particular things
about leaves; one has reference to the shape of the leaf, and the other
to the way in which the edges are formed. To simplify the explanation,
the drawings which I make pertain only to the edges. That will be
sufficient for one time.

"Look at Fig. 14. The edges are like the teeth of a saw. This is called
the serrate leaf. The rose and the common nettle have such leaves.

"Fig. 15 shows a leaf with a saw tooth edge wherein the teeth themselves
have a lot of little saw teeth, as in the nettle-leaved bell-flower, and
this is called bi-serrate.

"Fig. 16 has very large, sharp teeth, not pointing in any particular
direction, like the oak leaf. This is called the dentate, or tooth.

"Fig. 17 has rounded projections instead of angular teeth, and is called
crenate. Ground ivy and horseradish have such leaves.

"When we make drawings of the shapes of the leaves that will take us
along another step, and thus enable us to find out just what kind of
tree or plant we are talking about."

[Illustration: _Fig. 16. Dentate. Fig. 17. Crenate.