The spider begins to cross them with adhesive threads near the end of the upper ray at S′. After fastening the end of the thread, she walks along toward the centre, scratching away all the time with her calamistrum, till she comes to a place, 5, where she can cross to the next ray. She crosses over, and goes outward toward S″, the thread shrinking as she goes, until, when she arrives at S″, it is just long enough to reach across to S′. She fastens it by laying it along the ray for a short distance, and goes inward again till she reaches 7, where she crosses to the next ray; and so on till the thread is finished to S‴′. Here she stops spinning, and goes up the lower ray to A, and along the upper one to 4, where she starts another cross-thread. This goes on till the whole web is filled, as in Fig. 39, nearly to the centre. When the web is finished, the spider goes up the thread A _o_, to within an inch or so of the twig to which it is fastened; turns round, and takes hold of the thread with her front-feet; then pulls herself backward with her hind-feet up to the twig. She thus tightens the web, and draws up a loop of thread between her front and hind feet, Fig. 39, lower figure. [Illustration: Fig. 39.] The net is now set for use, and she stands holding it till something touches it; then she lets go with her hind-legs, and the net springs forward, bringing more threads into contact with the insect, and sliding the spider along the line toward A. If she thinks it worth while, she draws up another loop, and snaps the web again. When she is satisfied that the insect is caught, she gathers up part of the web till she comes to him, covers him with silk, and carries him up to her roost. There are other spiders of this group that make round webs, just like those of the _Epeiridæ_, Fig. 28, except in the adhesive threads being spun with the calamistrum. FLYING SPIDERS. Often, in summer, the bushes are covered with threads, attached by one end, blowing out in the wind; and bits of cobweb are blowing about, with occasionally a spider attached. To account for such threads, curious theories have been thought of; among others, that spiders are able to force the thread from their spinnerets, like water from a syringe, in any direction they choose.