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 other lines being merely a framework to support it. In spinning the sticky line, the spider begins at the outer edge of the orb, and passing around it, fastens this line to each radius as it goes. Thus a second spiral is made. The turns of this spiral are placed quite close together, and the first spiral, which is merely a temporary support, is destroyed as the second spiral progresses. Fig. 93 represents a web in which the second spiral is made over the outer half of the radii. In this figure, _aa_ represents the temporary stayline; _bb_, the sticky spiral; and _cc_, the fragments of the first spiral hanging from the radii. [Illustration: _Fig. 94. Wasp, with head, thorax and abdomen separated._] [Illustration: _Fig. 95. Spider, showing division of the body into cephalothorax and abdomen._] [Illustration: _Fig. 96. Lower side of cephalothorax of a spider;_ md_, mandible;_ mx_, maxilla;_ p_, palpus;_ l_, lower lip;_ s_, sternum._] 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 which the legs are attached; and the abdomen or hind part of the body (Fig. 94). In the spiders the head and thorax are grown together, forming a region which is known as the _cephalothorax_; to this the _abdomen_ is joined by a short, narrow stalk (Fig. 95). Spiders differ also from insects in the number of their legs, spiders having eight legs and insects only six. Spiders have two pairs of jaws, which, except in the Tarantula family, move sidewise like the jaws of insects. The first pair of jaws are called the _mandibles_. Each mandible consists of two segments, a strong basal one and a claw-shaped terminal one, at the tip of which the poison gland opens (Fig. 96). The second pair of jaws is known as the _maxillæ_. These jaws are situated just behind the mandibles, one on each side of the mouth. Each maxilla bears a large feeler or _palpus_. These palpi vary greatly in form; frequently, especially in females, they resemble legs; hence many spiders appear to have five pairs of legs. In the male spiders the last segment of the palpus is more or less enlarged, ending in a complicated, knob-like structure (Fig. 97). It is thus easy to determine the sex of a spider by merely examining the palpi. [Illustration: _Fig. 97. Maxilla and palpus of male house-spider._] [Illustration: _Fig. 98. Head of spider, showing eyes and mandibles._]