e class gradually heat the potato juice with its starch
sediment, stirring all the time to distribute the sediment evenly. They
will find that a little less than boiling temperature dissolves the
starch. This will show them that heat is necessary for the solution of
starch, and a heat much greater than that in the body, hence raw starch
is indigestible. Recall the milk lesson and the uselessness of starch as
a component of milk, unless the milk be cooked.

Squeeze the juice from a sour apple or lemon, and note the taste.
Explain that all fruit juices contain more or less acid. The effects of
this acid in the body are similar to those of mineral matter.

Protein is also found in plant juices; but in such small quantities that
it may be disregarded as a source of food supply.

GENERAL COMPOSITION OF PLANT JUICE

Water; mineral matter; flavouring matter; starch or sugar, or both; acid
(in fruit juice).

LESSON III

COMPOSITION OF SOLID MATERIAL IN CELLS OF SEEDS

This part of the lesson may be developed as follows:

1. Seeds contain the building material for new plants, as well as their
food for a short time.

2. Plants and animals require much the same material to build and feed
them.

3. Animals require water, mineral matter, protein, sugar, starch, and
fat.

4. Plants require the same; but the seed being a storehouse part of the
plant, it will not have sugar, and water has to be supplied when the new
plant is to be formed.

5. Seeds contain, therefore, mineral matter, protein, starch, and fat.

NOTE 1.--Seeds will grow in water until their
stored food is used: they must then be planted
in soil, to get further nourishment.

NOTE 2.--The two fuel foods, starch and fat,
are not found together in abundance in seeds;
one or the other will be much in excess. For
instance, in walnuts there is a great deal of
fat, while in peas and beans there is scarcely
a trace of fat, but the starch is abundant.

COMPARATIVE FOOD VALUE OF DIFFERENT PARTS OF PLANTS

Only a very general idea of this should be attempted. The food value of
any part of a plant can be roughly estimated by considering the office
of that particular part in plant structure. Nature study will assist in
this. The root collects the food to send it to the parts above; the stem
is a hallway through which the food is carried in a more diluted form.
The leaves serve the purpo