102 Life and Immortality. 
seemed to know, through the guidance of the same dumb 
and unerring instinct which teaches it to cement its under- 
ground dwelling, but would that same instinct teach it to 
construct so wonderful a dome-like house as the one 
described for the preservation of its after-life, and one so 
eminently fitted by its position, shape, size and entrance to 
secure the necessary shelter, warmth and air for its protection 
and development? I apprehend not. Nothing short of a 
reason, similar to that in man, but differing in degree, would 
enable it to grasp the situation in which it found itself to be 
placed when nearing its final change, and plan with the view 
of carrying out the ultimate aim of its existence. 
Fortunately, these insects are appointed to return at — 
periods so distant that vegetation has a chance to recover 
from the injuries which they inflict. Were they to appear 
at shorter intervals, our forest- and fruit-trees would be 
entirely destroyed by them. They are, moreover, subject 
to many accidents, and have many enemies, which contribute 
to diminish their numbers. Their eggs are eaten by birds, 
and the young, when they leave the egg, are preyed upon 
by ants, who mount the trees for that purpose, or take them 
upon the ground as they are about to enter upon their pro- 
tracted larval career. Blackbirds eat them in the spring 
when turned up by the plough, and hogs, when allowed to 
run at large in the woods, root them up and devour large 
numbers, especially just before the arrival of the period of 
their final transformation, when they are lodged only a few 
inches below the surface of the soil. Many perish in the 
egg by the closing up of the bark and wood that constitute 
the walls of the perforations, thus burying the eggs before 
they have hatched, and others, no doubt, are killed by their 
perilous descent from the trees. 
As its name implies, this insect generally requires seven- 
teen years to complete its transformations, a fact that was 
first pointed out many years ago by the botanist Kalm. The 
late Prof. Riley, who had given this species a great deal of 
