THE INSTINCT OF SPIDERS 135 



accuracy its viscid spiral. Beautiful parallel lines were 

 stretched across every segment except the experi- 

 mental segment. In this segment was a vacant space, 

 for I there divided the line as fast as the spider laid it. 

 But the spider could not appreciate this, though every 

 time it crossed the segment it found that its measuring 

 line was lost. It worked unheeded. Twenty-eight 

 times it drew a line across the experimental segment 

 and twenty-eight times I severed it. The spider could 

 not recognize that, although it was bridging this 

 segment again and again, yet it was constructing no 

 network. It circled on, ever diminishing the circum- 

 ference of its spiral as it drew nearer to the centre. 

 Finally it sealed off the end of the spiral and ran away 

 to the centre to wait for entangled insects. The spider 

 was satisfied. Without doubt it believed that it had 

 constructed a perfect snare and was quite oblivious of 

 the fact that one whole segment was almost entirely 

 absent. 



That the spider is a slave to its own instinct, that 

 it is able to recommence its work only at the point 

 where the instinctive round is broken, can be still 

 further exemplified. I discovered a snare with the 

 spider busy at its work. Ten turns of the viscid spiral 

 were complete. I divided all the turns of the viscid 

 spiral right round the snare so that only the hub, the 

 radii and the temporary spiral remained attached to 

 the foundation-lines. My interference disturbed the 

 spider and it hurried away to the edge of the snare. 

 I wished to know what it would do on its return. It 

 would find a snare with a hub, radii and temporary 

 spiral, but with no viscid spiral. What will it do? 

 Will it commence to lay down a spiral from the 



