2. Sow does the amount of water and other
materials in the leaves compare with what we
found in autumn?

Gather and tabulate results, as directed on
page 76; also, see Chart 7, page 82. In the
course of the spring it is interesting to repeat,
each month, the experiments there outlined for
the purpose of determining the relative amounts
of water, carbon and other materials, at the dif-
ferent stages of development of the leaves.
the grammar grades. 383

number "work.
Queries :

A. How much water is thrown off by the leaves
of plants?

1. Under experiment (A), weigh the plant
carefully, calculate how much water is thrown
off into the air during the daylight.
2. Compare the amount thrown off by each
plant when in the sunshine with that thrown
off during a cloudy or rainy day.
3. The amount of water thrown off during
the night equals what part of that thrown off
of plants during the day.
4. Estimate the leaf surface of a tree, say,
the oak, ash, maple, etc. Do this by counting
the leaves on some of the smaller branches; and
estimate their area, and then consider what
part this branch is of the whole tree.
5. At the rate indicated by the plants in the
bottle, how much moisture does an oak tree lift
into the air during the hours of sunlight.
Note. — It has been estimated that a full-grown oak
tree has about 700,000 leaves and that an elm tree
has about 1,000,000.
