AGELENA

Before going farther afield, let us investigate one of the spinners of the sheet-webs that are so unpleasantly familiar in the house. We object to them on very obvious grounds, first as evidence of neglect and bad housewifery, and secondly as repulsive objects when covered by accumulations of dust which their firm texture and their durability make inevitable.

The common house-spiders belong to the family Agelenidae. It is quite likely that their original home was in a warmer climate where they lived out of doors, but that was long ago, and now they uniformly select buildings of some sort for their operations. They have, however, even in this country, several open-air cousins, and most people know the great sheet-web spider of the hedge-rows, though its name—Agelena labyrinthica—may be new to them. Its web consists of a closely woven wide-spreading sheet connected with a tube of even denser material, in the mouth of which the spider may generally be seen lurking, a rather sinister object. If a better view of the animal is desired it is only necessary to agitate the web slightly and the spider runs forward to investigate. It is a large species as British spiders go—about three quarters of an inch in length—with the abdomen rather prettily marked with oblique white streaks.

It is very unlike our garden spider in certain points of structure; its body is more elongate and rather rigid, with little play of action between the cephalothorax and the abdomen; its legs are notably long, and so are two of its spinnerets, which can be seen protruding beyond the abdomen as we look down upon it.

But we shall gain little information by looking at the completed web, and our best plan is to take the animal home and observe it in captivity. We have prepared for its reception a box about a foot square, with a gauze top and a movable glass front.

It is not such an easy matter to secure the spider, which can run like a lamp-lighter, and which has a way of escape at the lower end of its tube. The safest way is suddenly to shut off this means of retreat with the finger and thumb of the left hand and simultaneously to present a glass phial at the mouth of the tube; the spider runs up into it and is taken without the risk of injury. It is never advisable to handle spiders, not because any British species is formidable, but because they so readily part with their limbs in order to escape, and the chances are that only a mutilated specimen will be obtained.

Now Agelena does not seem to be a particularly engaging pet, but it has its points. In the first place, it very quickly makes itself at home; a short time is spent in exploring its new quarters, but it adapts itself almost at once to its changed situation. Moreover it is of a peaceable and domestic disposition and the male and female live amicably together, which is far from being the case among the Epeiridae, whose peculiar marital relations are often—quite wrongly—attributed to the whole tribe of spiders. A male garden-spider courts the female at the risk of his life, and it is not surprising that he should evince great hesitation and caution in his advances. If his attentions are unwelcome, or even if they have been accepted, he will be promptly trussed up and eaten unless he beats a hasty retreat. But with Agelena the conjugal relations are exemplary, and harmony reigns in the home. The question of food is certainly a difficulty, but if insects are let loose in the cage the spider will attend to the catching of them. In some cases raw meat has been found a satisfactory substitute.

After a brief exploration of the box the captive soon becomes busy, going to and fro across its cage and attaching lines to the sides at some height up from the floor. So fine is the work that for a long time hardly anything is visible, and the movements of the animal are the only clue to what is taking place. By and by it becomes evident that a sort of skeleton platform has been spun across the box, upon which the spider is able to walk. It is continually strengthened by new threads, and braced by stay-lines above and below. It has been hardly possible to follow the operations by which this has come about, and even now we are chiefly aware of the existence of the platform because we see the spider walking upon it; its movements seemed very scrambling and unmethodical, but they have resulted in the foundation of the sheet-web and its terminal tube. But now it begins to behave quite differently, and another phase of the work has clearly begun; it crawls about over the almost invisible foundation lines with a most curious gait, using its long legs to sway its body from side to side, raising and depressing its abdomen at intervals, and as this motion continues a beautiful gauzy sheet of incredibly fine texture gradually grows into view. What is happening is that the spider is strewing over the foundation lines multitudinous threads from its long posterior spinnerets, which are beset on their under surface with numbers of hair-like spinning tubes from each of which the silk is issuing. All day long the process goes on, and by slow degrees the web increases in density. Indeed for days after the structure is complete the spider spends odd moments in going over the ground again till the sheet, and especially the tube proceeding from it to a corner of the box, are so closely woven as to have become almost opaque, and its occupant at length appears to be satisfied with his handiwork, and retires into the tube to wait patiently for casual visitors.

July is a good month in which to experiment with Agelena, for if the captives include female specimens some further spinning operations of a very complicated description may be observed. The time of egg-laying is at hand and elaborate preparations have to be made, but if the experimenter wishes to see the whole process he must be prepared to sacrifice his night’s rest, for the most critical part of the performance takes place in the small hours of the morning. We will describe what occurred in the case of one Agelena.

The approaching oviposition was heralded several hours beforehand by the animal commencing to weave a hammock-like compartment from the roof of the box and above the sheet-web. This chamber was about four inches long and was constructed precisely in the same manner as the sheet, to which it was braced by lines from various points of its under surface. Its construction occupied the whole day previous to the laying of the eggs, and not until half an hour before midnight was it completed. Within this compartment, close to the roof, the spider next wove a small sheet one inch long, working diligently in an inverted position, ventral surface upwards. After a quarter of an hour it rested for an equal space, apparently exhausted by its prolonged efforts. An hour and three quarters intermittent work served to complete the sheet, the spider varying the monotony of its sinuous walk round this small area by occasionally walking over it and strengthening the lines which attached its angles to the roof.

A marked change now became observable in the manner of working. The animal abandoned its incessant to and fro motion but began to jerk its body up towards the sheet, throwing silk strongly against it. At the same time the posterior spinnerets were actively rubbed together and the long posterior spinnerets separated and brought together again with a scissor-like action. The result of this performance was to invest the under surface of the small sheet with a coating of flossy silk quite unlike the ordinary web in texture, the purpose of which soon became evident, for at about a quarter past two the spider began to deposit its eggs upwards, against this loose-textured silk, aiding the egg-mass to adhere by occasional upward jerks of the body. This occupied between five and ten minutes, and as soon as it was accomplished the under surface of the egg-mass was covered by a layer of flossy silk similar to that against which it was laid, the eggs being thus entirely enveloped in a coating of soft loose-textured material. This was next covered in by a sheet of firm texture like that of the original web.

It might be supposed that the work was at length finished and that a well-earned rest might be enjoyed, but this was far from being the case. The spider remained as active as ever though an hour or two passed before the object of its industry was evident. All this time it was incessantly climbing backwards and forwards between the egg-sheet and the hammock and generally scrimmaging round in the most unaccountable way, but it gradually became evident that the eggs were being enclosed in a wonderful transparent box of filmy silk with the egg-bearing sheet for its roof. By nine o’clock it was of moderate strength and opacity, and the spider, having worked “the clock round,” no longer laboured continuously. Days elapsed, however, before it was entirely finished to the satisfaction of the spider, which remained all the time in close proximity to the box and could with difficulty be frightened away, but clung tenaciously to it when interfered with.

Now this remarkable performance, which any reader endowed with sufficient patience may observe for himself, gives food for thought. The spider has never seen a cocoon constructed and has no model to work by, and yet it performs with absolute precision all the stages, in their proper succession, of a work which involves quite a number of different spinning operations, nor does the absence of light by which to work trouble it in the slightest. It seems hard to believe that this is not a sign of high intelligence and that the spider is probably quite unconscious of the object for which it has laboured so long and so aptly. But how otherwise explain this curious fact? If the eggs are removed the moment they are laid the work is continued precisely as if they were still there. The box is laboriously built round the place where they ought to be, and the spider refuses to budge from the empty casket, though there is no longer any treasure to guard.

Clearly as the egg-laying time approaches the spider feels an irresistible blind impulse to perform in a definite order certain complicated actions. It is like a machine actuated by an internal spring, and in the spider’s case the internal spring is the inherited nervous mechanism we call instinct, which urges it to actions which it is not in the least necessary that it should understand.