nd, is nourished
upon mineral or inorganic matter. It can make its own food from the soil
and the air, while animals can only live upon that which is made for
them by plants. These are thus the link between the mineral and animal
kingdoms. Ask the scholars if they can think of anything to eat or drink
that does not come from a plant. With a little help they will think of
salt and water. These could not support life. So we see that animals
receive all their food through the vegetable kingdom. One great use of
plants is that they are _food-producers_.

[Footnote 1: Reader in Botany, for use in Schools. Selected and adapted
from well-known authors. Ginn & Co., Boston, New York and Chicago, 1889.
I. Origin of Cultivated Plants.]

This lesson may be followed by a talk on food and the various plants used
for food.[2]

[Footnote 2: The Flour Mills of Minneapolis: Century Magazine, May, 1886.
Maize: Popular Science News, Nov. and Dec., 1888.]

2. _Clothing_.--Plants are used for clothing. Of the four great clothing
materials, cotton, linen, silk, and woollen, the first two are of
vegetable, the last two of animal origin. Cotton is made from the hairs of
the seed of the cotton plant.[1] Linen is made of the inner fibre of
the bark of the flax plant. It has been cultivated from the earliest
historical times.

[Footnote 1: Reader in Botany. II. The Cotton Plant.]

3. _Purification of the Air_.--The following questions and experiments are
intended to show the pupils, first, that we live in an atmosphere, the
presence of which is necessary to support life and combustion (1) and (2);
secondly, that this atmosphere is deprived of its power to support life
and combustion by the actions of combustion (2), and of respiration (3);
thirdly, that this power is restored to the air by the action of plants
(4).

We have the air about us everywhere. A so-called empty vessel is one
where the contents are invisible. The following experiment is a good
illustration of this.

(1) Wrap the throat of a glass funnel with moistened cloth or paper so
that it will fit tightly into the neck of a bottle, and fill the funnel
with water. If the space between the funnel and the bottle is air-tight,
the water will not flow into the bottle.

[Illustration: FIG. 1.]

Do not explain this in advance to the pupils. Ask them what prevents
the water from flowing into the bottle. If they are puzzled, loosen the
funnel, and show them that the water will