To show how water gets into the roots of plants. Water passed up into
the egg through the skin, or membrane, and forced the contents up the
glass tube until it began to overflow.]

[Illustration: FIG. 15.
To show osmose (see page 19).]




CHAPTER III

SOILS


The soil considered agriculturally, is that part of the earth's crust
which is occupied by the roots of plants and from which they absorb
food and moisture.


RELATION OF SOIL TO PLANTS

We have learned that plant roots penetrate the soil to hold the plant
in a firm and stable position, to absorb moisture and with it plant
food. We learned also that for roots to do these things well, the soil
in which they grow must be mellow and firm, and must contain moisture
and plant food, air must circulate in its pores and it must be warm.

How can we bring about these conditions? To answer this question
intelligently it will be necessary for us to study the soil to find