6 NATURE’S CRAFTSMEN 
graph wire. It also serves the spider as a foot¬ 
bridge. Follow its length closely. This is usu¬ 
ally not over twenty-two inches, though the An¬ 
gular spider, a tree species, is said to have a drag¬ 
line often eight or nine feet long. At the end of 
the line is the spider’s retreat: in some instances 
a burrow in the earth, in others a leaf rolled into 
a little tubular shelter, in others a tent made by 
joining a few leaves together with bits of silk— 
all depending on the size and kind of the spider. 
“ In each instance, the spider is safely hidden, 
all but its hind leg; this you will find stretched 
out with the toe firmly grasping the line. Upon 
the foot of the spider is a wonderful comb-like 
structure which may aid it in getting messages. 
Go back and drop some bait into the center of the 
web and see what happens. Instantly the net is 
set vibrating, and the spider shoots down the 
drag-line almost instantaneously. It-” 
“ Wait a minute,” demanded Tommy, his in¬ 
terest making him both brusque and unceremoni¬ 
ous. “ How does the spider know what jarred 
the web? The wind must often shake it. Doesn’t 
the spider come down then? ” 
“ It does not,” averred Uncle John stoutly. 
“ This has been proven over and over. The spi¬ 
der knows the difference in the vibration made 
by the struggle of a prisoner and that of a mere 
shaking caused by the wind. It remains abso- 
