82 Life and Immortality. 



the legs show signs of strengthening, and she is able to 

 draw them gradually towards her. A few up-and-down 

 movements, and she manages to get into the web again. 



That which, more than anything else, discriminates spiders 

 from other animals is their habit of spinning webs. Some 

 of the mites spin irregular threads upon plants, or cocoons 

 for their eggs, and many insects cocoons in which to 

 undergo their changes from larva to imago, but in the 

 spiders the spinning-organs are much more complicated, 

 and used for a greater variety of purposes, for making 

 egg-cocoons, silk linings to their nests, and nets for catching 

 insects. The spider's thread differs from that of insects, in 

 being constituted of a great number of finer threads laid 

 together, while soft enough to coalesce into one. Each 

 spinneret is provided with a number of little tubes, which 

 convey the viscid liquid that forms the thread from glands 

 in the spider's body. In Agalena the two hinder spinnerets 

 are long, and have spinning-tubes along the under side of the 

 last joint. 



When about to produce a thread the spider presses the 

 spinnerets against some object and forces out from each 

 tube enough of the secretion to adhere to it, when the spin- 

 nerets are moved away, drawing the viscid liquid out, which 

 hardens at once into threads for each tube. A band of 

 threads is formed when the spinnerets are kept apart, 

 but when closed together the fine threads unite into one 

 or more large ones. Commonly the spinning is aided by 

 the hinder feet, which guide the thread, keeping it clear of 

 surrounding objects, and even pulling it from the spin- 

 nerets. 



Spiders are best known and hated as animals that bite. 

 Their biting-apparatus, the mandibles, are located in front of 

 the head. Partly in the basal joints of these organs and 

 partly in the head, the poison-glands are seated, from which 

 is discharged through a tube the venom, which makes spi- 

 ders so much to be feared. This tube opens at the point of 



