What conditions are necessary for the root to do its work?

We know that a part of the work of the root is to penetrate the soil
and hold the plant firmly in place. Therefore, it needs a firm soil.

We know that the part of the root which penetrates the soil is tender
and easily injured. Therefore, for rapid growth the root needs a
mellow soil.

We know that part of the work of the root is to take moisture from the
soil. Therefore, it needs a moist soil.

We know that part of the work of the root is to take food from the
soil. Therefore, it needs a soil well supplied with plant food.

We know that roots stop their work in cold weather. Therefore, they
need a warm soil.

Another condition needed by roots we will find out by experiment.

=Experiment.=--Take two wide-mouthed clear glass bottles (Fig. 16);
fill one nearly full of water from the well or hydrant; fill the other
bottle nearly full of water that has been boiled and cooled; place in
each bottle a slip or cutting of Wandering Jew (called also inch
plant, or tradescantia, and spiderwort), or some other plant that
roots readily in water. Then pour on top of the boiled water about a
quarter of an inch of oil--lard oil or cotton-seed oil or salad oil.
This is to prevent the absorption of air. In a few days roots will
appear on the slip in the hydrant water, while only a very few short