THE GEOMETRICAL SNARE 113 



completion of the snare there were forty-four turns on 

 the broad side and only thirty on the narrow side. 

 It was evident that the cause of the reversal of the 

 spiral was the eccentricity of the snare, and that it 

 was the means adopted by the spider to perform the 

 difficult operation of winding spirals round an eccentric 

 point with the least possible loss of parallelism and 

 symmetry. 



This reversal of the spiral is to my mind an excellent 

 example of the plasticity of instinct. No two snares 

 can be exactly alike ; some are more, others are less 

 eccentric. All must vary somewhat in their construc- 

 tion. In some the number of reversals are few, in 

 others many, possibly in others there may be none 

 required. In some the reversed spiral may be so 

 short as to connect but two radii, in others it may 

 connect ten. In every snare the reverses must vary 

 in number, in order and in length. What a wonderful 

 flexibility of instinct must a spider possess to adapt its 

 work to such changing circumstances and construct in 

 the end a perfect architecture. Every snare the spider 

 weaves must differ in some way from its predecessor 

 and must demand some modification in the plastic 

 instinct which may never before have been called into 

 action. It would not be surprising to see every snare 

 varying in length or breadth or even in the number 

 of the turns of the spiral, for such variations are those 

 of the ordinary course of nature and directed to no 

 vital end. But it is wonderful to think that this varia- 

 tion in the reversal of the spiral is so necessary, so 

 intricate, so universal, and is directed to the ultimate 

 purpose of mathematical perfection in the complexity 

 of the snare. It is indeed strange to witness the 



