a 
1905] NATURE STuDY—No. 30. 185 
into a right relationship with the big Nature world about us.— 
Study our home surroundings. 
- Down in a low corner of the grounds the soil is covered with 
much decaying vegetable matter. Ferns and mosses grow there 
and the leaf-screen of the trees allows but little sunlight to reach 
the damp soil. Year after year the organic matter accumulates 
in this corner, for pieces of limbs and bark are added to the leaf- 
mould, and year after year the decay continues. It is worth our 
while sometimes to observe the disintegrating agents at work. 
The leaves and twigs are often eaten by borers, sow-bugs, and 
centipedes, and the fungi continue the work on the stems which 
they have made to fall. Rupturing the bark of the dead limbs 
black pustules of many kinds of ‘‘sac-fungi”’ may be seen. The 
fine threads of these fungi have already penetrated the wood of 
the limb in all directions, and have come to the surface to produce 
their spores. On many limbs are slimy masses of the ‘‘ slime- 
fungi,” which also sends fine threads through the wood in search 
of food. 
We may observe, moreover, that the bark breaks down less 
rapidly than the wood, for bark, we know, is largely composed of 
corky matter, which absorbs water but slowly ; and as the de- 
structive agents require moisture, its break-down is quite slow. 
The lichens, mosses and alge that live on the bark, no doubt, 
hasten the operation, but the main agents are certain larger fungj 
and the bark-beetles. Moulds and bacteria tollow and break down 
the tissues much farther. Soon this vegetable matter becomes 
mixed with the soil, forming a new soil from which mushrooms 
and other similar forms get their food-material. The decay con- 
tinues through-the activity of other delicate underground fungi 
attached to the rootlets of trees, whose threads explore the ground 
in every direction. Ina few years the vegetable tissue, therefore, 
is completely broken down and incorporated with the mineral 
matter to form humus soil. 
