e lungs as fuel.

The stems, roots, branches, etc., of most plants consist principally of
_woody fibre_.

Their seeds, and sometimes their roots, contain considerable quantities
of _starch_.

[Name the parts of the plant in which the different proximates
exist.

State what you know about flour.

Do we know that different plants have ashes of different composition?]

The _protein_ and the _oils_ of most plants exist most largely in the
_seeds_.

The location of the proximates, as well as of the inorganic parts of the
plant, show a remarkable reference to the purposes of growth, and to the
wants of the animal world, as is noticed in the difference between the
construction of the straw and that of the kernel of wheat.

The reason why the fine flour now made is not so healthfully nutritious
as that which contained more of the coarse portions, is that it is
robbed of a large proportion of protein and phosphate of lime, while it
contains an undue amount of starch, which is available only to form fat,
and to supply fuel to the lungs.

Different plants have ashes of different composition. Thus--one may take
from the soil large quantities of potash, another of phosphoric acid,
and another of lime.

By understanding these differences, we shall be able so to regulate our
rotations, that the soil may not be called on to supply more of one
ingredient than of another, and thus it may be kept in balance.

[How are farmers to be benefited by such knowledge?]

The facts contained in this chapter are the _alphabet of agriculture_,
and the learner should not only become perfectly familiar with them, but
should also clearly understand the _reasons_ why they are true, before
proceeding further.

SECTION SECOND.

THE SOIL.

CHAPTER I.

FORMATION AND CHARACTER OF THE SOIL.

[What is a necessary condition of growth?]

In the foregoing section, we have studied the character of plants and
the laws which govern their growth. We learned that one necessary
condition for growth is a fertile soil, and therefore we will examine
the nature of different soils, in order that we may understand the
relations between them and plants.

[What is a fixed character of soils?

How is the chemical character of the soil to be ascertained?

What do we first learn in analyzing a soil?

How do the proportions of organic or inorganic parts of soils compare
with those of plants?

Of what does the organic part of soils consi