od, prepared for the next year, so that the plant can live on its
reserve fund and devote its whole attention to flowering. These roots
are often good food for animals. There are some plants that store their
surplus food in their roots year after year, using up in each season the
store of the former one, and forming new roots continually. The Sweet
Potato is an example of this class. These are _perennials_. The food in
perennials, however, is usually stored in stems, rather than in roots, as
in trees. _Annuals_ are generally fibrous-rooted, and the plant dies after
its first year. The following experiment will serve as an illustration of
the way in which the food stored in fleshy roots is utilized for growth.

Cut off the tapering end of a carrot and scoop out the inside of the
larger half in the form of a vase, leaving about half of the flesh behind.
Put strings through the upper rim, fill the carrot cup with water, and
hang it up in a sunny window. Keep it constantly full of water. The
leaf-buds below will put forth, and grow into leafy shoots, which, turning
upwards, soon hide the vase in a green circle. This is because the dry,
starchy food stored in the carrot becomes soft and soluble, and the supply
of proper food and the warmth of the room make the leaf-buds able to grow.
It is also a pretty illustration of the way in which stems always grow
upward, even though there is enough light and air for them to grow
straight downwards. Why this is so, we do not know.

3. _Differences between the Stem and the Root.--_Ask the pupils to tell
what differences they have found.

_Stems_. _Roots_.

Ascend into the air. Descend into the ground.
Grow by a succession of similar Grow only from a point
parts, each part when young just behind the tip.
elongating throughout.
Bear organs. Bear no organs.

There are certain exceptions to the statement that roots descend into the
ground; such as aerial roots and parasitic roots. The aerial roots of the
Ivy have been mentioned. Other examples of roots used for climbing are
the Trumpet Creeper _(Tecoma radicans)_, and the Poison Ivy _(Rhus
Toxicodendron)_. Parasitic roots take their food ready-made from the
plants into which they strike. The roots of air-plants, such as certain
orchids, draw their nourishment from the air.

The experiment of marking roots and stem has been already tried, but it
should be rep