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As spiders grow larger, they must moult from time to time. This is an interesting process. The spider hangs herself by a thread from the spinnerets to the centre of the web. In a short time 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 now breaks irregularly along the sides and back, and shrinks together in a bunch, leaving the spider suspended only by a short thread from the spinnerets, her legs still being trammelled by the old skin. Fifteen minutes of violent exertion releases her from the encumbrance, when she drops down, hanging by her spinnerets like a wet rag. She can do nothing in this condition, not even draw her legs away from an approaching hand. In ten or twelve minutes 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.