194 ARTHROPODS: ARACHNIDS. 



holes in each knob. Through these the invisible silken 

 threads pass out, — more than four thousand at a time, 

 — and at a little distance from the knobs all these 

 unite into one, forming the single line of spider web 

 which all are so familiar with. As the threads issue 

 from the knobs they are a sticky fluid, — which has 



Fig. 340. — Spider — L3'cosa. 



been secreted in little bags in the abdomen ; but this 

 hardens into silk as soon as it comes to the air. The 

 length of the line which the Spider is able to produce is 

 truly wonderful. Dr. Wilder wound nearly two miles 

 of silk, in less than a day, from his celebrated Ncpliila 

 plujnifics, — a Spider which he discovered in South Car- 

 olina. The kinds of Spider are very numerous, and 

 most of them spin some sort of a net-like web, in or 

 near which they live, and by means of which they cap- 

 ture insects for food. The House Spider spreads a flat 

 net in the corners of rooms. The Geometric Spider 

 spreads a vertical net, which is made in the most beau- 

 tiful manner, radiating lines running from the center, 



