92 * USEFUL BIRDS. 
when the tree falls. Lacking the nesting sites, protection, 
and shelter once afforded them among the trees, they must 
find other shelter, or perish. The interests of birds and 
trees are identical, and each must protect the other for the 
good of all. Birds are conspicuously useful in distributing 
the seed, and in planting, pruning, and protecting the trees. 
THE FOREST PLANTERS. 
If we take a white pine cone, containing seeds, break it 
open and examine a seed, we find that it is enveloped in a 
membrane with a wing-like appendage. Now take the seed 
and toss it into the air, and it will descend to the ground with 
a rotary motion, like that of a pickerel 
spoon when drawn through the water. 
As the seed descends, its wing in rotat- 
Fig.30.—Thewingedseed ing forms a spiral plane at an angle with 
pau ate the direction of its descent, serving as 
a parachute to sustain it in the air. If there is the slightest 
breeze, the seed floats off upon it and descends diagonally 
to the ground. The pheffomenon is much the same as that 
observed in falling seeds of the ash and some other deciduous 
trees. Such seeds are winged, like the pine seed, for dis- 
tribution. Although they will not float on a gentle breeze, 
like thistle or dandelion seeds, still, in a strong wind they 
are carried fifteen or twenty rods, or more. When pine 
seeds fall to the ground they soon separate from their wings. 
A heavy washing rain or the foot of some animal may bury 
them with earth mould, or falling leaves may cover them, 
and the planting is done. Should they fall upon the surface 
of a lake, the gentle breeze would waft them alang over the 
surface, like a fleet of little boats, to islands or distant shores ; 
should they fall upon a stream, they would float away with 
the current. 
Although the seeds of many forest trees do not grow their 
own wings, we find them as widely distributed as the seeds 
of the pine. Notice the distribution of the wild cherry along 
the roadsides. In spring we see here and there, on bushes 
or trees, the webs of the tent caterpillar. They are usually 
found upon the apple and wild cherry; and if, late in May, 
