234 



line, it walks back to the outer framework and attaches this line an 

 incli or two from tlie first. h\ this way all of the radiating lines 

 are drawn. The next stop is to stay these radii by a spiral line, 

 which is begun near the center, and attached to each radius as it 

 crosses it. The turns of this spiral are as far apart as the spider can 

 convenientlv reach. 



All of the threads spun up to this stage in the construction of the 

 web are dry and inelastic. The spider now proceeds to stretch upon 

 this framework a sticky and elastic line, which is the most important 

 part of the web, the otlier lines being merely a framework to sup- 

 port it. In spinning the sticky 

 line, the spider begins at the 

 outer edge of the orb, and pass- 

 ino; around it fastens this line 

 to each radius as it goes. Thus 

 a second spiral is made. The 

 turns of this spiral are placed 

 (juite close together, and the first 

 spiral, which is merely a tempo- 

 rary support, is destroyed as the 

 second spiral progresses. Figure 

 1 1 7 represents a web in which 

 the second spiral is made over 

 t!ie outer half of the radii. In 

 this figure, ««, represents the 

 temporary stay-line ; hh, the 

 sticky spiral ; and cc, the fragments of the first spiral hanging from 



the radii. 



The Parts of a Spider. 



Spiders differ much in appearance from the true insects. In the 

 insects the body is composed of three regions : the head, the thorax, 

 to wliich the legs are attached ; and the al)domen or hind body (Fig. 

 118). In the spiders the head and thorax are grown together, form- 

 ing a region wliich is known as the cephalotJwrax j to this the ahJo- 

 men is joined by a short, narrow stalk (Fig. 119). Spiders differ 

 also from insects in the number of their legs, spiders having eight 



legs and insects only six. 



'6U 



117. — Xeaiiy completed orh-wch. 



