THE INSTINCT OF SPIDERS 139 



those events or to alter a sincrle link in the lonor chain 

 of action is far beyond the simple mind of the Arancus. 



I pass now to another question. How will geo- 

 metrical spiders behave when their snares are inter- 

 changed? The snare of an Araneiis is made with such 

 precision ; each line is so accurately measured by some 

 portion of the spider's body that I fancy the complete 

 structure is specially adapted to the movements of its 

 owner. If we take a spider from a snare and place it on 

 another snare, we see that the movements of the spider 

 are more difficult in the new snare, and it often injures 

 the fabric in its progress. The intricacies of the new 

 snare are not suited to this spider. Each is best fitted 

 to the product of its own precision. 



But a spider will often rest content with a snare 

 other than its own. I interchange two Aranei, placing 

 each on the other's web. They are first scared, hasten 

 away to the foundation-lines, but, taking confidence 

 after some twenty minutes, return to the centre. 

 There they wait. They grow restless ; they test the 

 radii with their fore limbs, vibrate the snare, make 

 short explorations towards the circumference as though 

 dissatisfied with their homes. Soon confidence in- 

 creases ; they remain passive at the centre and seldom 

 stir from the resting-place unless to seize an entangled 

 prey. They are satisfied with the exchange. Each is 

 probably quite oblivious of the fact that it is not in its 

 own snare. 



I make a more marked exchange. I place an 

 Aranezis in the snare of a Tetraznatha and a Tetra- 

 gnat ha in that of an Aranetis. What will happen now ? 

 The snares are more dissimilar. One is horizontal, 

 the other vertical. The spiral of the Araneus is closely 



