THE GARDEN SPIDER 



235 



continued in gradually diminishing turns until the centre 

 is almost reached. 



Why, we may ask, should two spiral lines be laid down 

 by the garden spider, one temporary and the other per- 

 manent ? The answer is that in its final state the spiral 

 line is meant to be adhesive, so as better to entangle flies, 

 but a viscid thread is too slippery to give foothold even 

 to the spider that 

 lays it down, and 

 moreover the viscid 

 coating is injured 

 whenever the spider 

 steps upon it. Since 

 the radii are too wide 4. f^ 

 apart towards the /( 

 circumference for the 

 spider to step from 

 one to another, she 

 lays a non-viscid 

 spiral line for her 

 own use, and bites it 

 away bit by bit when 

 she passes over it for 

 the last time. 



The original spiral 

 line is not completely removed. Towards the centre a 

 few non-viscid threads are left, and these constitute the 

 watching station of the spider. Here she hangs head 

 downwards by the claws of her hind legs, waiting for a 

 victim, which cannot fail to agitate one or more of the 

 radii, and thus give her instant warning. 



The permanent spiral thread is coated with a sticky 

 film, as we see by its retaining dust, and adhering to the 

 finger-tip when lightly touched. When fresh-spun, this 

 thread has a uniform covering of fluid, poured out no 

 doubt from special glands, though these have not been 

 clearly identified. As soon as the thread is properly 



FIG. 51. Extremity of abdomen (a) of 

 garden spider, and two pairs of spinners (b 

 and c). When these spinners are separated, 

 another small pair is exposed. 



