NATURE'S GEOMETRICIANS 227 



worm encases its body with a mile or more of 

 gleaming silk, but there its usefulness is ended 

 as far as the silkworm is concerned. But spiders 

 have found a hundred uses for their cordage, 

 some of w T hich are startlingly similar to human 

 inventions. 



Those spiders which burrow in the earth hang 

 their tunnels with silken tapestries impervious 

 to wet, which at the same time act as lining to the 

 tube. Then the entrance may be a trap-door of 

 soil and silk, hinged with strong silken threads; 

 or in the turret spiders which are found in our 

 fields there is reared a tiny tower of leaves or 

 twigs bound together with silk. Who of us has 

 not teased the inmate by pushing a bent straw 

 into his stronghold and awaiting his furious on- 

 slaught upon the innocent stalk ! 



A list of all the uses of cobwebs would take 

 more space than we can spare; but of these the 

 most familiar is the snare set for unwary flies, — 

 the wonderfully ingenious webs which sparkle 

 With dew among the grasses or stretch from bush 

 to bush. The framework is of strong webbing and 

 upon this is closely woven the sticky spiral which 

 is so elastic, so ethereal, and yet strong enough to 

 entangle a good-sized insect. How knowing seems 

 the little worker, as when, the web and his den of 

 concealment being completed, he spins a strong 

 cable from the centre of the web to the entrance 

 of his watch-tower. Then, when a trembling of 



