trees supply shade from the sun and shelter from the wind,
thus retarding evaporation. The roots of the trees hold the soil from
being washed away. The dead leaves and fallen stems provide humus, and,
on account of the water-holding capacity of humus, the forest floor acts
like a sponge, preventing floods in wet seasons and droughts in dry
times.

6. ANIMALS.--Pupils should make a list of all burrowing animals and look
for examples. The work of the earthworms is especially interesting. By
eating the soil, they improve its texture and expose it to the air.
Their holes admit air and water to the soil. The worms also drag leaves,
sticks, and grass into their holes and thus add to the humus.

Darwin estimated that the earthworms in England passed over ten tons of
soil an acre through their bodies annually. This is left on the surface
and makes a rich top-dressing.

TILLING THE SOIL

1. It makes the soil finer, thus increasing the surface for holding film
water and enabling it to conduct more water by capillarity.

2. It saves water from evaporation. (See Experiments 7 and 8, Form III.)

3. It aerates the soil, enabling roots to thrive better.

4. It drains (hence warms) the soil, assuring more rapid growth.

5. It kills weeds.

A large part of the work with soils may be done in connection with the
garden studies, though most of the above mentioned experiments may be
tried in the school-room. In ungraded schools any of the experiments may
be made instructive to all the Forms.

Pupils should be asked to acquaint themselves with the common implements
used on the farm. They should ascertain the special service rendered by
each. See _Circular 156_, Dominion Department of Agriculture.

GARDEN WORK

The work in gardening for Form IV should be connected with some definite
line of experimental work. The garden should be so planned that a part
of it can be used exclusively for experimental work. Co-operation with
the Farmer's Experimental Union of the Ontario Agricultural College at
Guelph is advisable at this point. The following list of experiments is
suggested as suitable for boys especially, but no pupil should attempt
more than one experiment each year.

EXPERIMENTS IN PLOTS OUT-OF-DOORS

Experimental plots may be of different sizes, according to the space
available, from a yard square to a rod square or larger. A plot 10 ft. 5
in. by 20 ft. 10 in. is almost 1/200 of an acre, so that the actual
yield on such a