and in some the body is more or less divided into two portions, but at least two pairs of legs will be found to be attached to the hinder portion; and neither harvestmen nor mites possess the spinnerets which are the most striking characteristic of the spider; some mites—like the “red spider”—can spin, but the mechanism by which that operation is performed is of quite a different nature.

Fig. 1. A, a Mite; B, a Spider; C, a Phalangid.

Having, then, very readily determined our specimen to be a true spider, we may as well use it to note some further structural points the detailed examination of which may be deferred till we have considered their functions. Note the jaws or chelicerae, consisting of a stout basal part and a fang which, when not in use, is shut down like the blade of a knife; note the pedipalps or feelers, exactly like small legs, but showing by their action that their function is sensory and not locomotor. If they are knobbed at the end, the specimen is a male, otherwise it is a female or as yet immature. Look closely at the front part of the cephalothorax, and several eyes will be visible—probably eight. They are not compound—divided into innumerable facets, like those of insects—but simple and smooth, though to make sure of this the use of a microscope would be necessary. Finally, obtain a view of the under surface of the abdomen, and note in front, on either side of the middle line, two semilunar patches of a lighter colour. These are the “lung-books,”—special breathing organs peculiar to these animals; two is the usual number, though certain spiders possess a second pair behind the first.

But the spinning mammillae or spinnerets are still more characteristic and more easily seen, though, curiously enough, it is not among the cleverest spinners that they are most conspicuous. In the family to which most of the cellar spiders belong (Agelenidae) and in the elongate brown or mouse-coloured spiders found lurking under stones (Drassidae) they are visible as little finger-like projections at the posterior end of the abdomen, but if we have taken our specimen from a circular web (Epeiridae) we shall have to look for them more closely. In these spiders they are beneath the abdomen near its termination, and are not visible from above. Moreover when at rest their tips are applied together so that they form a small rosette in surface-view, or, in profile, a slight cone.

The best way to capture a spider for examination is to induce it to run up into a small glass specimen tube—for spiders readily part with their legs if handled roughly—and if we have adopted this method we shall see the spinnerets in use as the animal crawls about the tube. It will not move without first attaching a silken cable to the glass, and this cable lengthens as the spider progresses, so that before long the interior of the tube will be a network of silken threads, and its sides will be flecked with little white specks where the threads have been re-attached for a new departure; and by observing closely we shall be able to note the extreme mobility of the spinnerets in action.

All spiders spin, but it is by no means all spiders that make snares for the purpose of catching prey. The fundamental purpose of the spinning organs seems to be to connect the spider with its point of departure. The jumping spiders (Attidae) make no snare, but this “drag-line” as it has been called comes in very useful when stalking prey on the vertical surface of a wall, when a miscalculation at the moment of pouncing upon it would entail a considerable fall were it not for such an anchorage. It can hardly be doubted—though of course it is incapable of proof—that all the more complicated spinning operations originated in this universal spider habit, but all known spiders have learnt to apply their power of making silk to other purposes. If they do not make snares they at least spin “cocoons” for the protection of their eggs, and if they have a definite home from which they emerge to seek food, such a retreat is always more or less lined with silk. It is clear that a spider cocoon is quite different from that of an insect; it encloses the eggs and is manufactured by the mother, whereas among the insects the larva makes the cocoon for the protection of the pupa or chrysalis into which it is about to turn. However far from exhaustive the foregoing study of spider structure may be it will suffice for our purposes, at least for the present, and we may proceed at once to an investigation of one of the most remarkable achievements in the way of spinning—the familiar circular snare or wheel-web of the garden spider.

CHAPTER III

THE CIRCULAR SNARE

Select the most perfect circular snare at hand, and examine it attentively. In the autumn, when the large garden-spider, Epeira diademata (fig. 2 A), is mature, it will probably be easy to find such a snare a foot or more in diameter. It is stretched within an irregular frame of foundation lines of extra thickness and strength, and consists of a large number of radii or spokes connected by what appear to be a series of concentric circles, in reality a continuous spiral, like the hair-spring of a watch. The central portion is different from the rest of the wheel. Probably in the very centre there is a vacant space and round this a hub, consisting of a spiral line different in appearance from that of the main spiral. It does not leave a radius exactly at the point where it strikes it, and the rather zig-zag effect has caused it to be known as the “notched zone.” Touch the web and it adheres to the finger, but all its lines are not adhesive. Test this with some fine-pointed implement, and the foundation lines, the radii and the notched zone will give negative results; the spiral line alone is viscid, and its viscidity is due to the presence of thousands of little beads of gummy matter strung on a thin elastic thread. The vast number and uniformity of these beads—estimated at 120,000 on a large web—excited the wonder and admiration of naturalists until it was proved that they were not deposited by the spider as beads at all, but as a uniform coating of viscid matter which subsequently arranged itself into equidistant globules easily explicable by the physicist. Indeed precisely the same phenomenon is seen on a dew-laden web, where similar but very much larger beads of water decorate all the lines.

From the hub of the wheel we shall very likely notice a rather stout cable diverging from the plane of the snare and leading to a nest of leaves spun together. Here the spider is to be found when not on duty in the centre of the wheel, and here it constructs its egg-cocoons.

This, then, is the complete circular snare, but we shall understand it much better if we watch the spider at work in its construction.

Fig. 2. A, the Garden Spider. B, diagram of a sector of the snare. f, foundation line; r, radius; v.s, viscid spiral; n.z, notched zone; h, hub.

The first business of the spider is to lay down the foundation lines. Any sort of trapezium—or even a