110 A NATURALIST IN HIMALAYA 



served as a measuring line from which to adjust 

 the outermost turn of the viscid spiral, it has bound 

 the radii together until the viscid spiral was in place, 

 it has served as a succession of many bridges to 

 convey the spider from radius to radius. All these 

 functions are now complete ; they take no part in the 

 ensnaring of the prey. The temporary spiral is there- 

 fore of no further use ; its presence any longer would 



FIG. 5. Diagram of reversal of spiral. 



(a) One method. 



(b) Another method. 



The spider has reversed at the point X. 



lead to loss of symmetry and to imperfection ; it is 

 therefore destroyed and disappears. 



I come now to consider another feature in the 

 architecture of the snare. If an Araneus be carefully 

 watched while constructing its viscid spiral, it will be 

 noticed that from time to time the spider stops, turns 

 about and commences to circle again round the snare 

 in the opposite direction. It rarely completes its spiral 

 from the first to the last turn by always circling in 

 the same direction. It is working to the right. It 

 suddenly halts, seals off the end of its spiral, turns 

 about, commences a new spiral and starts off on a 



