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SPIDERS. 



109 



like a spider. The eyes become darkei-colored, marks on the thorax become more 

 distinct, and a dark stripe appears across the edge of each segment of the abdomen. 

 Tlie hairs are long and few in number, and arranged in rows across the abdomen and 

 along the middle of the thorax. Before the next moult they usually leave the cocoon 

 and for a time live together in a web spun in common. Where large broods of young 

 spiders live together they soon begin to eat one another, and if kept in confinement 

 one or two out of a cocoon-full may be raised without any other food. The young of 

 the running spiders, Lycosidse, when they come out of the cocoon, get on their mother's 

 back, and are carried round by her for some time. 



As spiders grow larger they have to moult from time to time. The spider then 

 hangs itself by a thread from the spinnerets to the centre of the web. The skin cracks 

 around the thorax just over the first joints of the legs, and the top part falls forward, 

 being held only at the front edge. The skin of the abdomen breaks irregularly along 

 the sides and back, and shrinks together in a bunch. The spider now hangs by a 

 short thread from the spinnerets, and works to free her legs from the old skin. 



That which more than anything else distinguishes spiders from other animals is the 

 habit of spinning webs. Some of the mites spin irregular threads on plants, or cocoons 

 for their eggs, and many insects spin cocoons in which to pass through the change from 

 larva to adult. 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 

 nest, and nets for catching insects. The 

 spider's thread differs from that of insects 

 in being made up of a gi'eat number of 

 finer threads laid together while soft 

 enough to unite into one. 



The external spinning-organs are little 

 two-jointed tubes on the ends of the spin- 

 nerets. There is a large number of these 

 little tubes on each spinneret, and in cer- 

 tain places a few larger ones, each tube 

 being the outlet of a separate gland. 

 When the spider begins a thread it 

 presses the spinnerets against some ob- 

 ject, and forces out enough of the secre- 

 tion from each tube 

 to adhere to it. Then 



it moves the spinnerets away, and the viscid liquid is drawn out 

 and hardens at once into threads, — one fi-om each tube. If 

 the spinnerets 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, covered with very fine threads pointing 

 towards the middle, where they unite, Fig. 155. 



The spinning is commonly helped by the hinder feet, which 

 guide the thread and keep it clear of surrounding objects, and 

 even pull it from the spinnerets. This is well seen when an insect has been caught in 

 a web, and a spider is trying to tie it up. She goes as near as she safely can, and 



Fig. 154. — Spinnerets of Epeira. 



Fig. 155. — End of 

 spider's thread. 



