out something about its structure, its composition, its
characteristics; also, how it was made and what forces or agencies
were active in making it. Are these forces acting on the soil at the
present time? Do they have any influence over the conditions which are
favorable or unfavorable to plant growth? If so, can we control them
in their action for the benefit or injury of plants?

We will begin this soil study with an excursion and a few experiments.

Go to the field. Examine the soil in the holes dug for the root
lessons, noticing the difference between the upper or surface soil and
the under or subsoil. Examine as many kinds of surface soils and
subsoils as possible, also decayed leaf mould, the black soil of the
woods, etc. If there are in the neighborhood any exposed embankments
where a road has been cut through a hill, or where a river or the sea
water has cut into a bank of soil, visit them and examine the exposed
soils.

=Experiment.=--Place in separate pans, dishes, plates, boxes, or on
boards, one or two pints each of sand, clay, decayed vegetable matter
or leaf mould or woods soil, and garden soil. The soil should be fresh
from the field. Examine the sand, clay and leaf mould, comparing them
as to color; are they light or dark, are they moist or not? Test the
soils for comparative size of particles by rubbing between the fingers
(Fig. 19), noticing if they are coarse or fine, and for stickiness by
squeezing in the hand and noting whether or not they easily crumble
afterwards.

=Experiment.=--Take samples, about a teaspoonful, of sand, clay and
leaf mould. Dry them and then place each in an iron spoon or on a