THE SPIDER 107 



of the web. Then radii are spun from a central httle l)all of 

 floss to the frame. The radii are, often at least, laid down 

 alternatelj^ on opposite sides of the centre. Tlie number of radii 

 formed by a species of spider is not perfectly constant, but 



Fig. 109. — Web of a line-weaver. Photo, by Emcrton. 



varies within limits. It would be an interesting occupation 

 to sketch a number of webs of Argiope, showing the variations 

 in the number of radii and the other details of form. After the 

 radii are placed, the spiral lines are laid down. In the com- 

 pleted web four regions are distinguishable, as follows, passing 

 from the centre outward: (1) the inner spiral zone, consisting 

 of four to eight turns at the centre; (2) the free zone in which 



