The Structure a?id Habits of Spiders. 41 



When the spider begins a thread, 



it presses the spinnerets against 



some object, and forces out enough 



of the secretion from 



each tube to adhere 



to it. Then it moves 



the spinnerets away ; 



and the viscid liquid 

 Fig. 19. is drawn out, and 

 hardens at once into threads, — 

 one from each tube. If the spin- 

 nerets are kept apart, a band of 

 threads is formed ; but, if they 

 are closed together, the fine 

 threads unite into one or more 

 larger ones. If a spider is 

 allowed to attach its thread to 

 glass, the end can be seen spread 

 out over a surface as large as 

 the ends of the spinnerets, cov- 

 ered with very fine threads point- 

 ing toward the middle, where 

 they unite, Fig. 21. 



The spinning is commonly 

 helped by the hinder feet, which rig. 20. 





~r 



•v ft 



