FOOD OF INSECTS. 417 



sibility of reconstructing them for many clays or some- 

 times weeks, during which not a single gnat regales their 

 sharp-set appetites. And when at length formed anew 

 or repaired, an unlucky bee or wasp, or an overgrown 

 fly, will perversely entangle itself in toils not intended 

 for insects of its bulk, and in disengaging itself once 

 more leave the net in ruin. All these trials move not 

 our philosophic race. They patiently sit in their watch- 

 ing-place in the same posture, scarcely ever stirring but 

 when the expected prey appears. And however repeat- 

 edly their nets are injured or destroyed, as long as their 

 store of silk is unexhausted, they repair or reconstruct 

 them without loss of time. 



The web of a house spider will, with occasional re- 

 pairs, serve for a considerable period ; but the nets of 

 the geometric spiders are in favourable weather renewed 

 either wholly, or at least their concentric circles, every 

 twenty-four hours, even when not apparently injured. 

 This difference in the operations of the two tribes de- 

 pends upon a very remarkable peculiarity in the con- 

 formation of their snares. The threads of the house 

 spider's web are all of the same kind of silk, and flies 

 are caught in them from their claws becoming entangled 

 in the fine meshes which form the texture. On the other 

 hand the net of the garden spicier is composed of two 

 distinct kinds of silk ; that of the radii not adhesive, that 

 of the circles extremely viscid 3 . The cause of this dif- 

 ference, which, when it is considered that both sorts of 



a May not the spinners mentioned by Leeuwenhoek (see above 

 p. 404, note) be peculiar to the retiary spiders, and furnish this viscid 

 thread ? 



VOL. I. 2 E 



