184 NATURAL HISTORY OF THE FARM 
One observes in the woods that different kinds of logs have 
very different behavior in decay. * Certain kinds, like poplar 
and willow, decay rapidly and soon disappear. Others, like 
chestnut and cypress, long persist. Some, like the oaks, lose 
the bark and sapwood quickly while the heartwood is still 
sound: others, like the yellow birch, preserve the hollow 
cylinders of bark intact, long after the wood has decayed and 
fallen from them. One finds the segments of the bark of 
birch kicked about over the forest floor, long after the 
trunks have vanished. The resinous knots of the pines 
persist far beyond all other parts of the tree. And with the 
differences in the character and content of the trunks, go 
differences in the population. The insects and fungi that 
work in pine logs are not the same species that work on logs 
of oak or willow. 
In the forest, where every inch of ground is densely filled 
with roots, the crumbling logs, as they settle into the earth, 
furnish a new place in which seedlings may get a foothold. 
Certain shrubs, like wild currant and raspberry, habitually 
spring up from seeds dropped upon fallen logs by birds; 
many trees, also, start in the same place from wind-sown 
seeds, and gradually settle with the disintegrating heap to 
the level of the ground. How often one finds in the woods 
a young birch tree or hemlock, standing astride a stump 
or fallen log with long leg-like roots reaching down either 
side into the soil. 
Gradually the moldering heap is dispersed by winds and the 
patter of raindrops and the stir of passing feet. The great tree 
has silently passed and left no sign; but the organic products 
it gathered in its lifetime have gone to the permanent enrich- 
ment of the soil. 
