Part 33

We have only to add to this lively narrative, that the hunting-spider, when he leaps, takes good care to provide against accidental falls by always swinging himself from a good strong cable of silk, as Swammerdam correctly states, and which anybody may verify, as one of the small hunters (Salticus scenicus), known by having its back striped with black and white like a zebra, is very common in Britain.

Mr. Weston, the editor of 'Bloomfield's Remains,' falls into a very singular mistake about hunting-spiders, imagining them to be web-weaving ones which have exhausted their materials, and which are therefore compelled to hunt. In proof of this he gives an instance which fell under his own observation!

As a contrast to the little elastic satin nest of the hunter, we may mention the largest with which we are acquainted,--that of the labyrinthic spider (Agelena labyrinthica, Walchenaer). Our readers must often have seen this nest spread out like a broad sheet in hedges, furze, and other low bushes, and sometimes on the ground. The middle of this sheet, which is of a close texture, is swung like a sailor's hammock, by silken ropes extended all around to the higher branches; but the whole curves upwards and backwards, sloping down to a long funnel-shaped gallery which is nearly horizontal at the entrance, but soon winds obliquely till it becomes quite perpendicular. This curved gallery is about a quarter of an inch in diameter, is much more closely woven than the sheet part of the web, and sometimes descends into a hole in the ground, though oftener into a group of crowded twigs, or a tuft of grass. Here the spider dwells secure, frequently resting with her legs extended from the entrance of the gallery, ready to spring out upon whatever insect may fall into her sheet net. She herself can only be caught by getting behind her and forcing her out into the web; but though we have often endeavoured to make her construct a nest under our eye, we have been as unsuccessful as in similar experiments with the common house spider (Aranea domestica). (J. R.)

The house spider's proceedings were long ago described by Homberg, and the account has been copied, as usual, by almost every subsequent writer. Goldsmith has, indeed, given some strange misstatements from his own observations, and Bingley has added the original remark, that, after fixing its first thread, creeping along the wall, and joining it as it proceeds, it "darts itself to the opposite side, where the other end is to be fastened!" Homberg's spider took the more circuitous route of travelling to the opposite wall, carrying in one of the claws the end of the thread previously fixed, lest it should stick in the wrong place. This we believe to be the correct statement, for as the web is always horizontal, it would seldom answer to commit a floating thread to the wind, as is done by other species. Homberg's spider, after stretching as many lines by way of warp as it deemed sufficient between the two walls of the corner which it had chosen, proceeded to cross this in the way our weavers do in adding the woof, with this difference, that the spider's threads were only laid on, and not interlaced. The domestic spiders, however, in these modern days, must have forgot this mode of weaving, for none of their webs will be found to be thus regularly constructed!

The geometric, or net-working spiders (Tendeuses, Latr.), are as well known in most districts as any of the preceding; almost every bush and tree in the gardens and hedge-rows having one or more of their nets stretched out in a vertical position between adjacent branches. The common garden spider (Epeira diadema), and the long-bodied spider (Tetragnatha extensa), are the best known of this order.

The chief care of a spider of this sort is, to form a cable of sufficient strength to bear the net she means to hang upon it; and, after throwing out a floating line as above described, when it catches properly she doubles and redoubles it with additional threads. On trying its strength she is not contented with the test of pulling it with her legs, but drops herself down several feet from various points of it, as we have often seen, swinging and bobbing with the whole weight of her body. She proceeds in a similar manner with the rest of the framework of her wheel-shaped net; and it may be remarked that some of the ends of these lines are not simple, but in form of a Y, giving her the additional security of two attachments instead of one.

In constructing the body of the net, the most remarkable circumstance is her using her limbs as a measure, to regulate the distances of her radii or wheel-spokes, and the circular meshes interweaved into them. These are consequently always proportional to the size of the spider. She often takes up her station in the centre, but not always, though it is so said by inaccurate writers; for she as frequently lurks in a little chamber constructed under a leaf or other shelter at the corner of her web, ready to dart down upon whatever prey may be entangled in her net. The centre of the net is said also to be composed of more viscid materials than its suspensory lines,--a circumstance alleged to be proved by the former appearing under the microscope studded with globules of gum. We have not been able to verify this distinction, having seen the suspensory lines as often studded in this manner as those in the centre. (J. R.)

Mason-Spiders.

A no less wonderful structure is composed by a sort of spiders, natives of the tropics and the south of Europe, which have been justly called mason-spiders by M. Latreille. One of these (Mygale nidulans, Walckn.), found in the West Indies, "digs a hole in the earth obliquely downwards about three inches in length, and one in diameter. This cavity she lines with a tough thick web, which, when taken out, resembles a leathern purse; but, what is most curious, this house has a door with hinges, like the operculum of some sea-shells, and herself and family, who tenant this nest, open and shut the door whenever they pass and repass. This history was told me," says Darwin, "and the nest, with its door, shown me by the late Dr. Butt, of Bath, who was some years physician in Jamaica."

A. The nest shut. B. The nest open. C. The spider, Mygale cæmentaria. D. The eyes magnified. E, F. Parts of the foot and claw magnified.]

The nest of a mason-spider, similar to this, has been obligingly put into our hands by Mr. Riddle, of Blackheath. It came from the West Indies, and is probably that of Latreille's clay-kneader (Mygale cratiens), and one of the smallest of the genus. We have since seen a pair of these spiders in possession of Mr. William Mello, of Blackheath. The nest is composed of very hard argillaceous clay, deeply tinged with brown oxide of iron. It is in form of a tube, about one inch in diameter, between six and seven inches long, and slightly bent towards the lower extremity--appearing to have been mined into the clay rather than built. The interior of the tube is lined with a uniform tapestry of silken web, of an orange-white colour, with a texture intermediate between India paper and very fine glove leather. But the most wonderful part of this nest is its entrance, which we look upon as the perfection of insect architecture. A circular door, about the size of a crown piece, slightly concave on the outside and convex within, is formed of more than a dozen layers of the same web which lines the interior, closely laid upon one another, and shaped so that the inner layers are the broadest, the outer being gradually less in diameter, except towards the hinge, which is about an inch long; and in consequence of all the layers being united there, and prolonged into the tube, it becomes the thickest and strongest part of the structure. The elasticity of the materials, also, gives to this hinge the remarkable peculiarity of acting like a spring, and shutting the door of the nest spontaneously. It is, besides, made to fit so accurately to the aperture, which is composed of similar concentric layers of web, that it is almost impossible to distinguish the joining by the most careful inspection. To gratify curiosity, the door has been opened and shut hundreds of times, without in the least destroying the power of the spring. When the door is shut, it resembles some of the lichens (Lecidea), or the leathery fungi, such as Polyporus versicolor (Micheli), or, nearer still, the upper valve of a young oyster shell. The door of the nest, the only part seen above ground, being of a blackish-brown colour, it must be very difficult to discover. (J. R.)

Another mason-spider (Mygale cæmentaria, Latr.), found in the south of France, usually selects for her nest a place bare of grass, sloping in such a manner as to carry off the water, and of a firm soil, without rocks or small stones. She digs a gallery a foot or two in depth, and of a diameter (equal throughout) sufficient to admit of her easily passing. She lines this with a tapestry of silk glued to the walls. The door, which is circular, is constructed of many layers of earth kneaded, and bound together with silk. Externally, it is flat and rough, corresponding to the earth around the entrance, for the purpose, no doubt, of concealment: on the inside it is convex, and tapestried thickly with a web of fine silk. The threads of this door-tapestry are prolonged, and strongly attached to the upper side of the entrance, forming an excellent hinge, which, when pushed open by the spider, shuts again by its own weight, without the aid of spring hinges. When the spider is at home, and her door forcibly opened by an intruder, she pulls it strongly inwards, and even when half-opened often snatches it out of the hand; but when she is foiled in this, she retreats to the bottom of her den, as her last resource.

Rossi ascertained that the female of an allied species (Mygale sauvagesii, Latr.), found in Corsica, lived in one of these nests, with a numerous posterity. He destroyed one of these doors to observe whether a new one would be made, which it was; but it was fixed immovably, without a hinge; the spider, no doubt, fortifying herself in this manner till she thought she might reopen it without danger.

The nest is nearly six inches in length, and is made of a double layer of silken web. The inner layer is yellowish, with a tinge of red, and although fine, very tough and strong. The outer layer is thick, coarse, dark brown, and rather flaky, the dark colour being probably caused by the earth which is mixed with it. The lid is made of eight or ten layers of coarse web, overlapping each other like the tiles of a house-roof, and the entrance of the nest is formed after the same fashion. If the lid be opened, the inside of the nest is seen to be of a different make from the exterior, being greyish-white, smooth, close-textured, and looking much like the finest kid leather.

The smaller illustration shows the spider in the act of emerging from its home.]

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"The Rev. Revett Shepherd has often noticed, in the fen ditches of Norfolk, a very large spider (the species not yet determined) which actually forms a raft for the purpose of obtaining its prey with more facility. Keeping its station upon a ball of weeds about three inches in diameter, probably held together by slight silken cords, it is wafted along the surface of the water upon this floating island, which it quits the moment it sees a drowning insect. The booty thus seized it devours at leisure upon its raft, under which it retires when alarmed by any danger." In the spring of 1830, we found a spider on some reeds in the Croydon Canal, which agreed in appearance with Mr. Shepherd's.

Among our native spiders there are several besides this one, which, not contented with a web like the rest of their congeners, take advantage of other materials to construct cells where, "hushed in grim repose," they "expect their insect prey." The most simple of those spider-cells is constructed by a longish-bodied spider (Aranea holosericea, Linn.), which is a little larger than the common hunting-spider. It rolls up a leaf of the lilac or poplar, precisely in the same manner as is done by the leaf-rolling caterpillars, upon whose cells it sometimes seizes to save itself trouble, having first expelled, or perhaps devoured, the rightful owner. The spider, however, is not satisfied with the tapestry of the caterpillar, but always weaves a fresh set of her own, much more close and substantial.

Another spider, common in woods and copses (Epeira quadrata?), weaves together a great number of leaves to form a dwelling for herself, and in front of it she spreads her toils for entrapping the unwary insects which stray thither. These, as soon as caught, are dragged into her den, and stored up for a time of scarcity. Here also her eggs are deposited and hatched in safety. When the cold weather approaches, and the leaves of her edifice wither, she abandons it for the more secure shelter of a hollow tree, where she soon dies; but the continuation of the species depends upon eggs, deposited in the nest before winter, and remaining to be hatched with the warmth of the ensuing summer.

The spider's den of united leaves, however, which has just been described, is not always useless when withered and deserted, for the dormouse usually selects it as a ready-made roof for its nest of dried grass. That those old spiders' dens are not accidentally chosen by the mouse, appears from the fact, that out of about a dozen mouse-nests of this sort found during winter in a copse between Lewisham and Bromley, Kent, every second or third one was furnished with such a roof. (J. R.)

Diving Water-Spider.

Though spiders require atmospheric air for respiration, yet one species well known to naturalists is aquatic in its habits, and lives not only upon the surface but below the surface of the water, contriving to carry down with it a sufficiency of air for the support of life during a considerable period of time. Its subaqueous nest is in fact a sort of diving-bell, and constitutes a secure and most ingenious habitation. This spider does not like stagnant water, but prefers low running streams, canals, and ditches, where she may often be seen in the vicinity of London and elsewhere, living in her diving-bell, which shines through the water like a little globe of silver: her singular economy was first, we believe, described by Clerck, L. M. de Lignac, and De Geer.

"The shining appearance," says Clerck, "proceeds either from an inflated globule surrounding the abdomen, or from the space between the body and the water. The spider, when wishing to inhale the air, rises to the surface, with its body still submersed, and only the part containing the spinneret rising just to the surface, when it briskly opens and moves its four teats. A thick coat of hair keeps the water from approaching or wetting the abdomen. It comes up for air about four times an hour or oftener, though I have good reason to suppose it can continue without it for several days together.

"I found in the middle of May one male and ten females, which I put into a glass filled with water, where they lived together very quietly for eight days. I put some duckweed (Lemna) into the glass to afford them shelter, and the females began to stretch diagonal threads in a confused manner from it to the sides of the glass about half-way down. Each of the females afterwards fixed a close bag to the edge of the glass, from which the water was expelled by the air from the spinneret, and thus a cell was formed capable of containing the whole animal. Here they remained quietly, with their abdomens in their cells, and their bodies still plunged in the water; and in a short time brimstone-coloured bags of eggs appeared in each cell, filling it about a fourth part. On the 7th of July several young ones swam out from one of the bags. All this time the old ones had nothing to eat, and yet they never attacked one another as other spiders would have been apt to do."

"These spiders," says De Geer, "spin in the water a cell of strong, closely-woven white silk, in the form of half the shell of a pigeon's egg, or like a diving-bell. This is sometimes left partly above water, but at others is entirely submersed, and is always attached to the objects near it by a great number of irregular threads. It is closed all round, but has a large opening below, which, however, I found closed on the 15th of December, and the spider living quietly within, with her head downwards. I made a rent in this cell, and expelled the air, upon which the spider came out; yet, though she appeared to have been laid up for three months in her winter quarters, she greedily seized upon an insect and sucked it. I also found that the male as well as the female constructs a similar subaqueous cell, and during summer no less than in winter." We have recently kept one of these spiders for several months in a glass of water, where it built a cell half under water, in which it laid its eggs.

Cleanliness of Spiders.

When we look at the viscid material with which spiders construct their lines and webs, and at the rough, hairy covering (with a few exceptions) of their bodies, we might conclude that they would be always stuck over with fragments of the minute fibres which they produce. This, indeed, must often happen, did they not take careful precautions to avoid it; for we have observed that they seldom, if ever, leave a thread to float at random, except when they wish to form a bridge. When a spider drops along a line, for instance, in order to ascertain the strength of her web, or the nature of the place below her, she invariably, when she reascends, coils it up into a little ball, and throws it away. Her claws are admirably adapted for this purpose, as well as for walking along the lines, as may be readily seen by a magnifying glass.

There are three claws, one of which acts as a thumb, the others being toothed like a comb, for gliding along the lines. This structure, however, unfits it to walk, as flies can do, upon any upright polished surface like glass; although the contrary is erroneously asserted by the Abbé de la Pluche. Before she can do so, she is obliged to construct a ladder of ropes, as Mr. Blackwell remarks, by elevating her spinneret as high as she can, and laying down a step upon which she stands to form a second, and so on; as any one may try by placing a spider at the bottom of a very clean wine-glass.