to the presence of ducts in the wood formed in the spring.
In other woods there are no ducts, or they are evenly distributed, but
the transition from the close autumn wood, consisting of smaller and
more closely packed cells, to the wood of looser texture, formed in the
following spring, makes a line that marks the season's growth.

[Footnote 1: Mr. Romeyn B. Hough, of Lowville, N.Y., will supply a package
of such sections for one dollar. The package will consist of several
different woods, in both cross and vertical section and will contain
enough duplicates for an ordinary class.

He also issues a series of books on woods illustrated by actual and neatly
mounted specimens, showing in each case three distinct views of the grain.
The work is issued in parts, each representing twenty-five species, and
selling with text at $5, expressage prepaid; the mounted specimens alone
at 25 cts. per species or twenty-five in neat box for $4. He has also
a line of specimens prepared for the stereopticon and another for the
microscope. They are very useful and sell at 50 cts. per species or
twenty-five for $10.]

Let each of the scholars take one of the sections of Oak and write a
description of its markings. The age is easily determined; the pith rays,
or _medullary rays_, are also plain. These form what is called the silver
grain of the wood. The ducts, also, are clear in the Oak and Chestnut.
There is a difference in color between the outer and inner wood, the older
wood becomes darker and is called the _heart-wood_, the outer is the
_sap-wood_. In Birds-eye Maple, and some other woods, the abortive buds
are seen. They are buried in the wood, and make the disturbance which
produces the ornamental grain. In sections of Pine or Spruce, no ducts
can be found. The wood consists entirely of elongated, thickened cells or
fibres. In some of the trees the pith rays cannot be seen with the naked
eye.

Let the pupils compare the branches which they have described, with a
stalk of Asparagus, Rattan, or Lily. A cross section of one of these shows
dots among the soft tissue. These are ends of the fibro-vascular bundles,
which in these plants are scattered through the cellular tissue instead of
being brought together in a cylinder outside of the pith. In a vertical
section they appear as lines. There are no annular rings.

If possible, let the pupils compare the leaves belonging to these
different types of stems. The parallel-veined leaves