Spider nets and their weavers have, I think, never been given quite their place in the world of wonders. As far as human profit is concerned, spiders are useless things; and have therefore missed, because, from that standpoint, they have not merited, popular favour. But no doubt their ingenuity as craftswomen stands very nearly on a level with that of the worker honey-bee. The waxen comb of the bee, whose perfection is due to the combined arts of engineer, mason, and geometrician, is very little superior in design and carrying-out to the spider’s web.
On these still, grey autumn mornings, the tendency of the eye is not to wander far afield, but to concern itself with the little things of the wayside close at hand; and so, more than at any other time of year, perhaps, the spiders and their ways come in for narrow scrutiny. And here is something, in the first loving investigation of which the uninformed, unread observer is much to be envied.
He notices in the outset that these fine silken snares, hung by the spiders in the hedgerows, are of two kinds—the one placed vertically across a gap in the surface of the thicket; the other placed horizontally, closing up some shaft or upward passage-way in the heart of the green bush. The vertical net is seen to be composed of a number of threads radiating from a common centre, and upon these threads an ever-increasing spiral line has been laid, forming a regular, meshed net. But the horizontal web has none of this geometric neatness. It is a mere expanse of fine tissue irregularly woven into a sort of crazy pattern, and slung hammock fashion, completely closing the chimney-like hollow wherein it has been made. From a view of the finished webs, two other facts will be noted—the vertical net is supported only by lines springing from its circumference, and the spider sits at its centre in front; the horizontal net is suspended by numberless fine lines attached at all points in its upper surface, while the spider clings to the under side as she lies in wait for her prey.
But it is in the actual weaving of the nets that the interest of the onlooker will be chiefly centred. The maker of the vertical, or cartwheel, pattern of web begins operations in various ways, according to the conditions imposed upon her by the weather and the spot she has selected. Webs made in calm seasons, or when only light airs are stirring, will have few mainstays, and these may be of considerable length; but in windy times the spider will stretch her snare on only short hawsers, using as many as may be necessary to make assurance doubly sure. But in either case she will commence the work in much the same way.
First she goes to the highest point on the windward side of her gap, and turning her head to the current, begins to pay out a line behind her. As this floats out, she continually tries it with her leg until she knows that the end of the line has caught in the opposite twigs. Then she runs to the middle of this horizontal line, dragging after her another thread which she has previously attached to her original starting-point. From the centre of the first line she lowers herself vertically, always dragging the second line in her rear, until she reaches a twig below. Here she draws her second line tight and fastens it, after which she climbs to the horizontal line and repeats the manœuvre, only this time from its leeward end. Thus the triangle of mainstays—the first essential in all spider-web making—is complete.
The weaving of the net within this triangular frame is the next work undertaken. The spider, when she first dropped from the centre of her uppermost thread, made a vertical line in descending. Some point on this line marks the centre of the future cartwheel pattern of web, and this central point the spider now finds unerringly, and begins to put in one by one the radiating spokes of the wheel. When all these spokes are in place, she returns to the centre, and revolving her body quickly, she forms upon it a close spiral of four or five turns. This is to be her seat and watch-tower, whence she will keep the whole web under observation. Having done this, she now—if the morning is at all breezy—carries temporary stay-lines from spoke to spoke all round the web, these isolated circles of thread occurring at intervals of an inch or so between centre and circumference. But on still mornings this part of her work is omitted as unnecessary, and she proceeds at once to the main spinning of the net.
The construction of the cross-threads between the spokes of the web is always commenced at the extreme outer edges of the space to be filled; and the spider works inwardly, carrying the thread round and round from spoke to spoke until she arrives within half an inch or so of the central small spiral. But the two are never joined: an interval is always left where the web consists of nothing but bare radiating lines. The snare is now finished. The spider takes up her station in the middle of the net, with no more to do for the rest of the day but take what fair chance, and her own crafty ingenuity, may provide.
Yet, having thus watched the making of a spider-web from start to finish, and having noted all the details of construction here set down, there is something more about the matter which, if it escape the observer, will leave him in the rather disgraceful plight of having missed the most wonderful thing of all.
The spider’s snare is not woven throughout of the same kind of thread. Two kinds are used, and the difference between them is apparent even to eyes of very moderate power. While the triangle and the radiating lines are made of plain silk, the cross-threads are corrugated, and look like strings of tiny, transparent beads. A touch of the finger will prove that these beads are really adhering drops of some glutinous fluid, whose use is not difficult to guess. But how do the beads get on the line, seeing that this, when first drawn from the spider’s body, is visibly nothing but a plain filament of silk, like the rest of the web?
The question has been asked many times, and the answer commonly given is, I have come to believe, an entirely erroneous one. We are told that the thread used for the cross-bars in a spider’s web, when it first emerges from the creature’s body, is only smeared, not beaded with the gluten; but that after attaching each segment of the spiral to the spokes, the spider gives it a twang with her foot, thus causing the gluten to separate into beads. Here then is a fact such as one would read in the nature books, and unquestionably accept. But a little independent experiment with various kinds of strings, elastic or non-elastic, and smeared with different glutinous substances, reveals the fact that no amount of twanging will induce the latter to divide into beads, such as one sees in the spider line. In every case, the tendency of the gluten in the experiment is to fly off altogether, or to gather to one side of the string.