ontribute to the needs of the lowly plants. It is probably
due to the action of these creatures that small relics of ancient men,
such as stone tools, are commonly found buried at a considerable depth
beneath the earth, and rarely appear upon the surface except where it
has been subjected to deep ploughing or to the action of running
streams.

Along with the earthworms, the ants labour to overturn the soil;
frequently they are the more effective of the two agents. The common
species, though they make no permanent hillocks, have been observed by
the writer to lay upon the surface each year as much as a quarter of
an inch of sand and other fine materials which they have brought up
from a considerable depth. In many regions, particularly in those
occupied by glacial drift, and pebbly alluvium along the rivers, the
effect of this action, like that of earthworms, is to bring to the
surface the finer materials, leaving the coarser pebbles in the
depths. In this way they have changed the superficial character of the
soil over great areas; we may say, indeed, over a large part of the
earth, and this in a way which fits it better to serve the needs of
the wild plants as well as the uses of the farmer.

Many thousand species of insects, particularly the larger beetles,
have the habit of passing their larval state in the under earth. Here
they generally excavate burrows, and thus in a way delve the soil. As
many of them die before reaching maturity, their store of organic
matter is contributed to the mass, and serves to nourish the plants.
If the student will carefully examine a section of the earth either in
its natural or in its tilled state, he will be surprised to find how
numerous the grubs are. They may often be found to the number of a
score or more of each cubic foot of material. Many of the species
which develop underground come from eggs which have carefully been
encased in organic matter before their deposition in the earth. Thus
some of the carrion beetles are in the habit of laying their eggs in
the bodies of dead birds or field mice, which they then bury to the
depth of some inches in the earth. In this way nearly all the small
birds and mammals of our woods disappear from view in a few hours
after they are dead. Other species make balls from the dung of cattle
in which they lay their eggs, afterward rolling the little spheres, it
may be for hundreds of feet, to the chambers in the soil which they
have previously p