The hub is next surrounded by what Dr. M‘Cook calls a “notched zone,” consisting of a few turns of spiral thread which serve to bind more firmly the spokes of the wheel. The most important part of the work is still to be performed. The lines hitherto laid down are perfectly dry and free from viscidity, so that an entangled insect would easily be able to free itself. A viscid spiral line remains to be spun, and the snare will be complete. The precise method of laying this down will vary somewhat according to the species, but, to refer again to the large Garden-spider, the proceeding is as follows:—Commencing at a point somewhat outside the notched zone, the creature rapidly works in a spiral thread of ordinary silk with the successive turns rather far apart. This forms a kind of scaffolding, by clinging to which the spider can put in the viscid spiral, which it commences at the _circumference_. Its action now becomes exceedingly careful and deliberate, though by no means slow, and so great is its absorption in the work that it may be observed quite closely with a hand-lens without fear of interrupting it. The proceeding consists in drawing out from its spinnerets with one (or both) of its hind legs successive lengths of a highly elastic line, which it stretches just at the moment of fixing it to a radius, and then lets go with a snap. There is no hesitation or pause for consideration, but there is a peculiar deliberateness in drawing out each length of the thread which, together with stretching and sudden release, require explanation. Now, it has already been mentioned that the framework and radii of the snare are not at all moist or adhesive. This, however, is not the case with the spiral, upon which the spider chiefly relies in capturing its prey. A close examination of it—even with the naked eye— will show it to be beaded over with little viscid globules which, under a low magnifying power, are seen to be arranged with remarkable regularity. [Illustration: FIG. 190.—=A=, =B=, =C=, =D=, Stages in the formation of the viscid globules of the web. ] A very convenient method of investigation is to carry off a newly-constructed web—or, better still, one not quite finished—on a piece of plate glass, to which it will adhere by reason of the viscid spiral, and on which it may be examined at leisure. Immersion in a staining fluid will colour the viscid spiral, and show its structure in a striking manner. It will appear to consist of a thread strung with beads of two sizes, occurring with pretty uniform alternation, though two of the larger beads are often separated by two or more of the smaller.