BMilding the Web 215 



apparatus, which is on the left wing-case. 

 They are right-handed. 



When you and I take an unpremeditated turn, 

 we spin round on our right heel. The left side, 

 the weaker, moves on the pivot of the right, the 

 stronger. In the same way, nearly all the 

 Molluscs that have spiral shells roll their coils 

 from left to right. Among the numerous species 

 in both land and water fauna, only a very few are 

 exceptional and turn from right to left. 



It would be interesting to try and work out to 

 what extent that part of the zoological kingdom 

 which boasts a two-sided structure is divided 

 into right-handed and left-handed animals. 

 Can dissymetry, that source of contrasts, be a 

 general rule? Or are there neutrals, endowed 

 with equal powers of skill and energy on both 

 sides ? Yes, there are ; and the Spider is one 

 of them. She enjoys the very enviable privilege 

 of possessing a left side which is no less capable 

 than the right. She is ambidextrous, as witness 

 the following observations. 



When laying her snaring-thread, every Epeira 

 turns in either direction indifferently, as a close 

 watch will prove. Reasons whose secret escapes 

 us determine the direction adopted. Once this 



