The Geometry of the Epeira's Web 



But we must not rely too much on this rule, 

 say others. The Angular Epeira, the Pale- 

 tinted Epeira and the Diadem Epeira, or 

 Cross Spider, all three more or less short- 

 limbed, rival the Banded Epeira in the spac- 

 ing of their lime-snares. The last two 

 even dispose them with greater intervening 

 distances. 



We recognize in another respect that the 

 organization of the animal does not imply an 

 immutable type of work. Before beginning 

 the sticky spiral, the Epeirae first spin an 

 auxiliary intended to strengthen the stays. 

 This spiral, formed of plain, non-glutinous 

 thread, starts from the centre and winds in 

 rapidly-widening circles to the circumference. 

 It is merely a temporary construction, where- 

 of naught but the central part survives when 

 the Spider has set its limy meshes. The 

 second spiral, the essential part of the snare, 

 proceeds, on the contrary, in serried coils from 

 the circumference to the centre and is com- 

 posed entirely of viscous cross-threads. 



Here we have, following one upon the 

 other, by a sudden alteration of the machine, 

 two volutes of an entirely different order as 

 regards direction, the number of whorls and 



395 



