Popular Science Monthly/Volume 33/October 1888/Spiders and their Ways

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SPIDERS AND THEIR WAYS.
By M. ÉMILE BLANCHARD,

OF THE FRENCH ACADEMY OF SCIENCES.

SPIDERS live in both hemispheres—from the torrid zone to the coldest regions. Over all the world they are distinguished by their singular aspects and curious habits. The largest and gayest-colored species are found in the tropics. In cold and temperate latitudes live smaller species and more tamely colored, which attract attention by other titles than that of their garb.

As classified by naturalists, the spiders compose an order of the class of Arachnida. They are the Araneids, a division so well characterized and perfectly circumscribed that it is sufficiently designated when it is named. In these animals the head and corselet are confounded into a single mass, at the upper part of which is a kind of dorsal buckler, supporting in front the organs of vision. The eyes are generally eight in number, but are variously grouped, according to the types. Walckenäer, at the beginning of this century, made the disposition of the eyes a criterion of distinction between the genera and species. More recently, some remarkable coincidences having been noticed between the disposition of the eyes and the habits of the species, it became recognized that that feature could be relied upon in an animal wholly a stranger to determine the conditions of its existence and the way it got its living. The eyes do not turn in their socket like man's, for the cornea is only a tegumentary part which remains transparent. This immobility is an imperfection which is amply compensated for by the different orientations of the numerous organs, and their dispersion and grouping in such a manner as to respond to all the visual necessities of the animal. Being silent animals, and never having to answer to a call, spiders are backward in distinguishing sounds. This fact is assured by some features in their conformation. The romances that have been woven about their fondness for music are purely illusory. The disturbances which they experience at the playing of violins and pianos are simply effects of the vibration of their webs. Alarmed by it, they quit their hiding-places and rim about in panic.

Beneath the front of the spider project two thick processes armed with a movable hook—the antennæ forceps—which conceal a poison-gland with a little tube running out to near the point of the hook. All who have seen a spider taking a fly have remarked how it stings its victim so as to kill it before introducing it to its mouth. At the edge of the buccal orifice of those species that live on fluids, exist only a simple tongue and two highly developed palpi behind it.

Spiders are differentiated from insects, which have six legs, by having four pairs of legs (Fig. 1). These members support hooks at their ends, which are working instruments of astonishing perfection. The body and limbs are covered with hair, fine down, and spines. These are the organs of touch, often of exquisite sensitiveness, planted in the skin. Under the microscope the downy hairs, which are hardly visible to the naked eye, appear fringed and bearded like incomparably delicate feathers. When we consider the habitual neatness of their clothing, to which grains of dust would so readily stick, we are satisfied that spiders are far from the hindmost in the care they give to their toilet. Their long, hooked legs perform an office that leaves nothing to be desired. At the extremity of the body may be found mobile articulated tubes, having solid walls, and the end truncated with a membranous surface, riddled with holes. By these microscopic openings escapes the liquid which, hardened in contact with the air, becomes the thread out of which the web and the cocoon are PSM V33 D809 Parts of a spider.jpgFig. 1.—Parts of a Spider.

1. Under part of a spider's body—t, the thorax or chest, from which the eight legs spring, and to which the head is united in one piece; f, fangs; p, palpi or feelers attached to the jaws; a, abdomen; b, breathing slits; s, six spinnerets, with thread coming from them.

2. Front of spider's head—c, eyes; p, palpi; l, front legs; h, hasp of fangs; f, poison fangs; j, outer jaws.
made. Although it is cited as the type of fineness, this thread is formed of several fibers, which adhere together on issuing from the spinneret. It is unrivaled for evenness, delicacy, and power of resistance.

The internal organization of the spider is even more admirable than the external parts. It would be hardly possible even to point out in this paper the most essential features of it. It would be going into long details to describe a muscular apparatus having a power of which the animal kingdom affords few examples, assuring wonderful precision and agility in movement; a nervous system whose enormous development accounts for faculties of a superior order; and a stomach of construction peculiarly adapted to a diet composed exclusively of fluids. It is written that spiders breathe by lungs. They have an aerial respiration, but it is by organs very different in structure from the lungs of man. They consist of minute pockets containing flattened sacks packed like the leaves of a book, through the walls of which the blood infiltrates, and the interior of which is penetrated by the air. Thus observed under water, the little sacks appear like so many sheets of silver communicating with the outside by slits at the bottom of the belly. Spiders have also a heart and a circulation of blood of the most complex character. The heart, which is on the dorsal face, is of an ideal anatomical structure, and long evaded the attempts of investigators to discover the vessels that carry the blood to the periphery of the body. The main vessels were finally traced out by means of colored injections in the European species, and the smaller ones afterward in the larger South American species. The study was a most charming one to the young naturalist who made it about forty years ago, revealing a beautiful force-pump action, executed by instruments of infinite delicacy, and a power with which no machine of human invention can be compared.

Spiders are generally very prolific; yet we never see their numbers increasing considerably in any country. Fecundity is always proportioned to the dangers that threaten individuals. The young of these creatures so skilled in spreading nets are tempting bits to the appetites of carnivorous birds. All the spiders lay eggs, the larvæ from which have already the form and aspect of their parents. While as mothers they are incomparably careful, vigilant, and devoted, spiders show no feeling except for their own progeny. From the moment the young are in a condition to leave their mother, they become isolated from one another. When not under the influence of maternal instincts, the spider lives only for herself, ignoring the existence of every other individual of her race, which she devours pitilessly whenever she finds one within her reach. In such a world there are, in fact, no loves. The females are believed to be absolutely indifferent. If a male desires to contract a marriage, he proceeds with unexampled precautions, as if he knew he would be ill received. At last, if he is adroit, he will enjoy an embrace of an instant, and then, making the best use of his legs, which are longer than those of his ferocious spouse, he gets away as quickly as possible, otherwise his relative weakness would make him a victim. Poor male spider! He can not know the joys of paternity, but he can doubtless renew again and again his short instants of pleasure, for the two sexes are represented in the most unequal manner, the females being ten or twenty times as numerous as the males. The facts just related apply to spiders in general. But the various types furnish examples of special industries, aptitudes, and manners, on account of which it is necessary to divide our subject into special histories.

On the edge of the forest, among the rough-barked trees, or in dilapidated walls in the open fields, one may see in hot, sunshiny days numerous little spiders, scattered singly or gathered in groups, among which no hostility is manifested. Parts of their bodies are sometimes glossy and brightly colored, sometimes adorned with regular and elegant designs, forming a fine white, yellow, or red pubescence. They are extremely lively, and seek the brightest light. If the amateur tries to catch one he will be disappointed, for it will escape him and get out of the way at a bound. These spiders, jumpers, belong to the group which naturalists call the saltatory spiders (Fig. 2). Some of them are disguised, as if for protective resemblance, with the costume of a hymenopterous insect, or under an aspect resembling that of ants. Producing only a small quantity of silk, they hide themselves in cracks in the walls or in fissures of bark in the shadow of the foliage, and PSM V33 D811 Jumping spider.jpgFig. 2.—Jumping Spider (Altus familiaris). make themselves a lodge out of a smooth or flossy tissue. At the laying of its eggs, the jumper shuts itself up in its shell. One species deposits its eggs without any covering; a more fortunate species incloses them in a sack with thin and almost diaphanous walls. Not having the faculty of spinning webs, the saltatory spiders are hunters, and have to fast if the weather is bad. On pleasant days they are to be found all around, and, having eyes all over the cephalic region, some of them quite small and others of enormous size, they can look accurately through all the surrounding space, which they explore slowly and with care. If a fly is in sight, the spider lances itself upon it with dizzy rapidity. It measures its distance so well that it rarely misses; but, if this should happen, no harm comes to it, for it has fixed a thread to its starting-point, which, unrolling as it leaps, prevents its striking upon the ground, and affords an easy road back to its position.

PSM V33 D811 Wolf and hunting spider.jpg
Fig. 3.—Wolf Spider (Lycosœ fertifera). Fig. 4.—Hunting Spider (Dolomedes mirabilis), with a bag of eggs, b.

Some spiders are wealthy, having at their disposal an immense quantity of textile matter, which is renewed continually; others produce but little, and have to live in cells under stones or dead leaves, in the cracks of trees, and in walls. They have to hunt their game in the fields, along the edges of the water, or among aquatic plants. They are the Lycosœ. (Fig. 3). The smaller, dark-colored species of central Europe have little to attract the eye; but occasionally the attention of the careful observer is directed to one which is running rapidly along the road or trying to hide itself in the grass. It is carrying a pure white, round shell—the sack containing the eggs—in making which it has expended all the silk it had (Fig. 4). A mother of incomparable vigilance, homeless, its eggs laid and well protected in the silky walls of the shell, it does not abandon the cradle of its offspring for an instant. If we succeed in seizing one of the animals during its journey and take away its cocoon, the spider, usually so timid, instead of running away, makes a show of fight against the aggressor. If the cocoon is on the ground, it makes most earnest efforts to take it up and run away as quickly as possible. As soon as the young are hatched they attach themselves to the body of their mother, and she carries them till they are strong enough to hunt a prey, crafty enough to deceive an enemy, and ungrateful enough to cease to recognize a mother whose care has become of no use to them. Large lycosas adorned with lively colors inhabit southern Europe, Africa, and some parts of Asia. They are wanderers like their congeners of cold and temperate countries, and have the advantage over them of a longer existence and of having fixed retreats. They dig a cell in the ground, tapestry its walls, and weave a barricade of crossed threads across the entrance. Among them is the tarantula, concerning the effect of whose bite many marvelous but fictitious stories are told.

PSM V33 D813 Aquatic spider and its diving bell.jpg
Fig. 5.—Aquatic Spider and its Diving-Bell.

The smaller rivers of Europe are inhabited by an aquatic spider, the Argyronetus aquaticus, the first observation of which was a considerable surprise to the Père de Lignac, who discovered it and first described it. It was in 1747, and he was bathing in a river near Mans, when, he relates, "I was surprised by a wonderful sight: bubbles of air, bright as polished silver, appeared to swim around me and follow me. Their free movements, which were not determined by the motion of the water or by the levity of the air, declared that they were animated. My surprise shortly became astonishment when I perceived that they were large spiders whose bodies were enveloped in air." Two years afterward, Lignac obtained several specimens of the argyronetus, and made a closer study of them. While their nearly constant abode is the water, they are, like most other spiders, air-breathers; consequently they need some special provision for providing themselves with air while living under the water, and for this purpose they possess the art of constructing a kind of diving-bell. It is an interesting sight to witness one of them making his air-cell. Clinging to the lower side of a few leaves, and securing them in position by spinning a few threads, the spider rises to the level of the water, with its belly uppermost, and, doubling up its hind-legs, retains a stratum of air among the hairs with which its body is covered. Then it. plunges into the water and appears as in the first stage of the making of its silvery robe. Going immediately to the spot it had chosen, it brushes its body with its paws, when the air detaches itself and forms a bubble under the leaf. The spider surrounds this bubble with the impermeable silky matter furnished by its spinneret. Returning to the surface, it takes in another layer of air, which it carries down and adds to the first one, also extending the envelope over it. The process is kept up till the "diving-bell" has reached the proper size, and is finished. The ideal form of the construction is that of a thimble, but it often assumes an irregular shape, like an inverted sack (Fig, 5). When the spider has taken possession of its redoubt it remains quiet in it, head down, watching for the appearance of an insect. Perceiving one, it seizes it and returns to its lodge, which it has secured against intruders by spinning threads across it, to devour its prey at its leisure. The argyroneti being as ferocious as other spiders, the matter of marriage involves a grave crisis to the male. If he should present himself bluntly at the female's diving-bell, the result of the application would probably be fatal to him. But his instincts are adequate to the occasion, and he uses diplomacy, stratagem, and address. He makes a diving-bell near the female's, and adds a wide gallery between them. When his preliminary operations have been finished, he breaks through the wall of the female's lodge and surprises her into an embrace which is not always disagreeable to her. The young live for some time with their mother, whose solicitude for her little family is unremitting. When they have become strong enough, the young ones accept the struggle for existence and separate, each one going, as its parents did, to construct its cell and live a solitary life.

We now change our point of observation, and look at a spider that lives still another kind of life—as an inhabitant of our homes (Fig, 6), In a corner of the room under the ceiling is stretched a PSM V33 D814 Common house spider.jpgFig. 6.—Common House Spider (Tegenaria medicinalis.) web, and on the web, watchful, stands a long-legged spider. It is the spider of all dwellings, and its presence is tolerated—the Tegenaria domestica. It has so pronounced a taste for dwelling-houses that it acts as if men's houses were built especially for it, A skillful weaver, it has at its disposal a quite abundant mass of silk. Its web is formed of an even material, which has been carded b/ tools of exquisite fineness, assuring the perfection of the work. When new, the web is a pure white; but it soon becomes soiled with dust and wears an unpleasant look, which, however, does not seem to give the proprietor any concern. The domestic spider is timid, and does not feel fully secure unless it has a good hiding-place to run to. It has reserved a vacant spot in the corner of the wall, and this is the road by which it steals away when it is alarmed. Beneath its web it has fixed a roomy hammock in which to take refuge. It deposits its eggs in a silken cocoon, which it hides under foreign bodies to conceal it from the greed of animals that would appreciate too well the delicious meats. During incubation, the mother watches the cocoon unceasingly, even forgetting to feed herself. When the young have escaped from their cradle, the starved mother returns to her web, where she sits and devours flies so numerously that the ground beneath becomes littered with their bodies. The domestic spider rarely inhabits the holes in rocks and the hollows of old trees, which are preferred by so many other creatures. Open-air species of the south and center of Europe, where the temperature is never rigorous, learn in the cold climates of the north, as in Scandinavia, to insinuate themselves into the houses—wise animals, that seem to know they will require a shelter from the cold.

We inhabitants of houses need not be above sharing our life with spiders. The part they perform is appreciated in the country, where they are not destroyed or disturbed in bedrooms or stables. The flies are a perpetual cause of torment to the people and to animals, and they perish in the webs of spiders, with perceptible decrease in their numbers. Spiders are, indeed, valuable servants given us by Nature.

On clear and sunny days, especially in the latter part of the summer, when a light breeze is blowing, long threads and flakes of a snowy whiteness may be seen floating in the air; or, covering the grass of the flowery meadows, they wave in the breeze and cause on the lawns shimmerings of strange effect. The peasantry of France call them the Virgin's threads. More accurately the naturalist would say they are the threads, abandoned as if to chance, of a kind of spider very common in the fields, which is called the gossamer spider. These spiders are wanderers, and frequent low plants and shrubs; small in size and loving the bright light, they wear lively colors which often confound them with the flowers and mask them from the pursuit of carnivorous animals. Their motions are abrupt and rapid, and their broad bellies give them a singular gait, something like that of crabs that we see running over the sea-beaches. They do not spin webs, but watch for passing insects, and, precipitating themselves upon their game with a sudden spring and extraordinary address, they rarely fail to secure it. The gossamer spider takes shelter under stones or plants or in holes. At the breeding-season they construct a sack to hold their eggs, and from that moment become sedentary and abstinent, watching over their posterity.

As day butterflies are gayer than night-moths, so do the epeïras show to better advantage than other spiders. They have for the most part either handsome colors or agreeable shades, and they hold the supreme rank as spinners. The European representatives of the group are modest in appearance, but in tropical countries the species to large size add luxury in dress. They are numerous enough on the globe to form a large family, that of the Epeïridœ, which is composed of many genera (Fig. 7); but the family is one of which the members are all so alike that they all bear the same general signs and pursue the same kind of industry. The epeïras weave webs of enormous proportions, with large, regular meshes. As they work in broad daylight, among the most beautiful features PSM V33 D816 Common epeira.jpgFig. 7.—Common Epeïra (Epeïra vulgaris). of nature, it is possible to follow them in all their operations, which are performed as if expressly to charm a philosopher. The spectacle may be witnessed every summer in the parks and gardens of Paris in the webs of the Epeïra diadema, which sometimes obstruct the streets. This spider is of a reddish-yellow color, marked on the upper part in dark hues with a figure that has been compared with the cross of St. Denis. Posted on a branch of privet, lilac, or cytissus, it puts forth a thread of silk which lengthens out under the very eye of the observer, and, caught up by the lightest breath of air, at last fastens itself to the limb of a shrub, often at a considerable distance from the point of departure. Subsequently the spinner herself mounts the aërial cord, and fastens it to the place where it has fixed itself, adjusting its position if necessary. The most skilled balancers in the circus would lose in the comparison with the epeïra of the gardens, which manoeuvres in every kind of attitude, upon a thread of extreme tenuity, with an ease and agility that defy all parallel. Threads carried to new points of support among the branches are adjusted so as to form a polygonal framework. This done, the spider returns upon the bridge which it first threw over, and stopping exactly in the middle, as if it had calculated the spot geometrically, it drops, head down, hanging to a thread which would divide the polygon in two. At the central point is fixed a fleck of silk that serves as a support to all the rays which diverge regularly to the periphery. The frame is made, but a final operation remains to be completed. An agglutinating thread must be stuck upon the rays, so as to form a spiral. The epeïra comes to the center of the web, draws the thread, which it attaches to the fleck of silk, and passes from ray to ray, describing circles away out to the exterior line of the frame. It will finish its work by returning from the circumference to the center, to interpose new circles between the former ones. It is impossible to realize a more sagacious combination to obtain a charming network, a lace of more admirable perfection (Fig. 8). Accidents will happen to the web of the epeïra. Gusts of wind during storms, or the stroke of a bird's wing, may mar its usefulness. The skillful spinner is only slightly affected by a disaster of the kind, for in less than an hour it will construct a new network. It is in cases where the web has suffered a single tear that it displays the resources of its intelligence; it makes the repairs that are called for in a way that will command the attention of the intelligent observer. Particular tools are necessary for executing works demanding precision. Accordingly, the claws of the epeïra are of a much more complicated construction than those of other spiders. One of them is cleft so as to form a fork, with which the artist is able to hold its threads and put them precisely where they are wanted to be.

PSM V33 D817 Web of the garden spider.jpg
Fig. 8.—Web of the Garden Spider.

In attack, the epeïra holds itself in the center of the web, head down. If an insect strikes against the network, it precipitates itself upon the game, which instantly finds itself held and tied in such a way that it can not escape. At the end of the summer this garden-spinner is depositing its eggs, and incloses them in a cocoon made of a different kind of silk from those which enter into the construction of its web. The poor mother, who must die in the autumn, takes care to hide the cradle of her offspring in as secluded a place as possible. The young spiders, when, hatched in the spring, remain together for several weeks as one family, after which they scatter and live isolated after the general manner of the daughters of Arachne.

In various parts of the East Indies and in the islands of the Pacific Ocean there are brilliant epeïras of superb proportions. The species are numerous, and the individuals occur, in many places, in multitudes. Some of these spiders prefer situations over water-courses, where they offer the most enchanting spectacle to the eye. In the midst of the most luxuriant and intricate vegetation the epeïras stretch their nets from the tops of the highest trees from one side of the river to the other. The traveler, looking up from his canoe beneath, views with admiration these delicate aërial structures, succeeding one another at short intervals and giving curious effects to the landscape. The great spider may generally be perceived on each of these nets, either motionless or in a state of high excitement, according as it is waiting for game or struggling with it. At some periods of the year, yellow, golden-like globes may be perceived suspended from the nets. They are the cocoons containing the eggs. In building their nets over streams, the epeïras are directed by a happy instinct. In the midst of a peculiarly bushy vegetation, they seek out broad, open spaces suitable for their establishments. In such spaces they are safest from their voracious enemies, and are at the same time conveniently situated to capture the insects that are their food. Not only are mammals and insects, lizards and birds fond of spiders, multitudes of people regard the handsome spinners as delicious meat. A large species, very abundant in the Polynesian Archipelago, is called the eatable epeïra (Epeïra edulis), and is much sought for by the islanders.

PSM V33 D818 Net of the triangle spider.jpg
Fig. 9.—Net of the Triangle Spider (Hyptiotes Americanus), about one half the usual length. The spider shown of the natural size.

The epeïras of Madagascar and the Mascarene Islands, according to the descriptions of Captain Dupré, are among the largest and handsomest of their kind. They build vertical webs which they attach to trees and shrubs by long threads having great power of resistance. The black epeïra predominates in the island of Reunion, the gilded epeïra in Mauritius—a magnificent animal, whose body, two inches or more in length, bears on the back a large space of bright yellow, relieved by two rows of black dots. The Madagascar species, which the Malagasy eat with relish, is yet more highly distinguished by the gayety of its dress. Its black dorsal buckler is clothed with a silvery pubescence; on its abdomen are harmoniously combined the colors of ebony, gold, and silver, and its legs are a fiery red. The disproportion in the size of the two sexes, marked enough in all spiders, is greatly exaggerated in these two species, of which the male is a mere myrmidon by the side of the female (Fig. 11).

PSM V33 D819 Supposed cocoon of the triangle spider.jpg
Fig. 10.—Supposed Cocoon (Egg-Case) of the Triangle Spider (Hyptiotes Americanus). A, the cocoon, of natural size, hung by thread-lines between hemlock twigs; B, the cocoon enlarged, seen obliquely, so as to show the triangular base.

In the Mediterranean countries, pretty epeïras, mostly of a silvery luster, fabricate a web with regular meshes and having a singular attachment, the use of which was first discovered by M. Vinson by observing one of the species common to Mauritius and Réunion. The webs are distinguished by a single silvery thread of enormous size compared with the other threads, running across them in zigzag folds. Not having seen any use made of this cable, M. Vinson cut it several times. It was replaced in a few hours. Flies and small insects flying against the web were seized and bound without calling this thread into use. Finally, a large grasshopper was ensnared, when in an instant the spider undid the large thread and quickly bound up in it the nimble giant, against which cords strong enough to hold flies would count for nothing. This, then, was its purpose, and it is hardly possible sufficiently to admire the instinct that prompted the preparation of it.

While most of the epeïras are lovers of the daylight, a few of them are active at night. Some species of the Mascarene Islands and Madagascar weave webs in the twilight which they destroy at dawn. During the day they hide under heaps of leaves which they have gathered up into a kind of nest. Their webs are coarsely spun, as becomes a nomad who has to pitch his tent anew every night, and has no time to waste in elegance. Some of them, however, are not satisfied to pass their days in heaps of leaves, but construct a kind of nest out of thin silk as a more eligible habitation. Of these more refined spiders, the Epeïra Borbonica, with its cherry-colored body and lustrous black legs, fixes its night-web and its day-tent to the roofs of houses, the projections of rocks, and the branches of large trees. The much larger lilac-colored Epeïra livida lives in similar luxury under the roofs of the Malagasy houses of the province of Imerina.

PSM V33 D820 Male and female nephila Chrysogaster.jpg
Fig. 11.Nephila Chrysogaster[1] Male and Female (one half natural size).

Leaving the grand epeïras, we may find, among vegetation and on walls, spiders whose weak proportions suggest their classification among the most insignificant of beings; but they play an important part in nature, and often serve the interests of cultivators by causing the destruction of numerous noxious insects. They are the Theridions. Some of them form a web with wide meshes, while others weave a regular tissue that rests directly upon the grass or is fixed upon other plants. They usually lurk under their webs. The females make several cocoons for their young and keep them in their nets. Some species build a dome-shaped shelter out of foreign bodies fastened together with threads. Sometimes the grapes in vineyards are covered with a web so fine that it escapes notice, and the grape is swallowed, web, spider, and all. Walckenaër named this species Theridium benignum, considering it beneficent. It lives in part on insects injurious to the vine, and its little web protects the grapes against the attacks of animals fond of good fruit, but which will not venture to embarrass their mouths with spiders' webs.

Spiders very generally take pains to isolate themselves from one another. It is a matter of instinct. Were it not so, there would be perpetual slaughterings. Two spiders meeting never fail to be taken with a terrible desire to devour each other; but there are curious exceptions to this rule. Minute spiders, called Linyphia, are not afraid to attach their nets to the large-meshed webs of the great epeïras. Some linyphias, like the Linyphia argyroides, are of curious forms, from four to six millimetres in size at the largest, and are adorned, on a reddish-brown ground, with golden and silvery colors that shine with a bright luster. They may be remarked in the south of Europe and in Africa, stationed on a little net within the meshes of the web of a superb epeïra. A feature that adds to the singularity of the grouping at a certain period is the presence of the cocoon of the linyphia, hanging by a slight thread from the web of the larger species; but treachery sometimes invades this association. An epeïra and a linyphia had lived in the best of relations. The larger spider was taken away from her abode, leaving the cradle of her family without defense. On the next day the linyphia had opened the cocoon and was quietly eating the half-hatched epeïras.

There are legions of spiders, superior to all the others, living in the shade, which are distinguished in an extraordinary degree by their habits and instincts, and perhaps by their intelligence. These species do not make webs, but have some of them only a shift for a refuge, others simple abodes, and still others quite sumptuous habitations. In temperate climates many of them construct in secluded spots, from a fine white silk, well-finished tunnels in which they make a nearly permanent residence. The Segestria are the most important members of this group. The Florentine or perfidious segestrium, the larger species of the genus, is of a rich black color, with antenna claws of bright emerald-green. It is spread through most of Europe, and lives under cornices, in the cracks of walls, and clefts of rock. While spiders of every other type have eight eyes, these tubicolar species have only six, those which look backward being wanting. They would be of no use to an animal living in a hole which is closed at one end.

PSM V33 D822 Bird eating spider killing a hummingbird.jpg
Fig. 12.—Bird-Eating Spider killing a Humming-Bird.

In the intertropical regions, especially in the Antilles, Guiana, and Brazil, there live enormous spiders which the European colonists call spider-crabs, and naturalists mygales. In them, suppleness and agility are united with muscular strength. Of all the representatives of the race which now engages our attention, the greatest physical power is exhibited in these. The mygales produce but little silk, only enough to give them a foothold on a vertical plane, to bar the opening of their holes, and to bind their prey. Their simple claws are not adapted to the purposes of tools. They are hunters, and live in the hollows of trees, which they do not leave, except to go on the chase. Their eyes are not distributed over the body, like those of other spiders, but are grouped upon an eminence in the middle of the cephalic region, two in front, two on each side, and two looking hindward, in such positions as to command simultaneous views in every direction. The larger, dark-colored species go abroad usually in the dusk and at night, and capture with equal boldness large insects, small lizards, and humming-birds (Fig. 12).

The abbé Sauvage, of Madrid, in 1768, astonished the French Academy of Sciences with the declaration that he had found a spider "that did not stretch any kind of web, but hollowed a burrow in the ground like a rabbit, and added a movable door to it." The species had been observed on the road-sides, around Montpellier, and on the banks of the little river Lez. A little while previously, a traveler, Patrick Browne, had found a nest of similar construction to this, but less perfect, in Jamaica. Since the last century these animals have been called in France, mason-spiders; in England, trap-door spiders. Judged by the organism as a whole, they appear to be related to the mygales, but they present several differences in detail. Like the larger mygales, the trap-door spiders have stout bodies, large legs, eyes grouped on an eminence, and a dorsal buckler; but in the lower parts of their forceps-antennae they have a row of points, a kind of rake, with spines on their paws, and teeth in their claws, which give a resemblance to microscopic combs. These are tools, working instruments, of which the mygales, compelled to find a home where they can, are destitute; naturalists call these spiders ctenizas.

The domiciles or burrows of the trap-door spiders are so well disguised that only an experienced observer can distinguish their presence on the surface of the ground. But, while without everything is as far as possible from suggesting a comfortable habitation, within the hole reign neatness, elegance, and graceful adjustments. These structures abound in the south of France and in nearly all of southern Europe. In compact earth, free from stones and gravel, they are built quite close to one another. Each one of them consists of a vertical hole or pit (Fig. 13), of a size proportioned to that of the architect, the cylindrical tube flaring toward the mouth. The walls are tapestried with the softest of satin, prepared from the silk which the animal spins. The entrance is most skillfully closed by a solid door, which can not easily be broken or pushed in. It is made of the material thrown out during the digging of the pit, the earthy particles being held together by the silky matter. The doors are cut in a conical shape, to fit the flare of the cylinder, and will not yield under pressure from without. The exterior of the door is uneven and rough, like the ground round it, whereby the attention of enemies is diverted. Inside it is tapestried like the nest itself. The hinge, made of a compact silk, possesses great resisting power, and such elasticity that the trap infallibly falls back as soon as it ceases to be held up. The place of a lock or bolt is taken by a series of little holes, like needle-pricks, arranged in a circle around the side of the door opposite the hinge. When the trap is down, the closing is so exact that the most delicate instrument can not be introduced into the interstice without danger of injury. If one tries to raise the trap, the spider, clinging to the walls of the pit, and inserting its claws into the holes of the cover, will make the most desperate efforts to keep it shut. In the evening, the spider comes out stealthily from its retreat, and goes to hunt its game in the fields. Having finished its meal, it returns to its home, lifts the trap-door with its claws, and disappears from view in an instant.

PSM V33 D824 Trap door spider nest.jpg
Fig. 13.—Nest of one of the Trap Door Spiders (Moggridge). D, the door which closes naturally by its own elasticity and weight; m, marks of the spider's claws when she has held it down from inside.

A much larger and finer species of cteniza than the one just described inhabits Corsica, Sardinia, and the parts of Italy near Mentone. Its nest, usually built in the light red clay of the region, is a beautiful construction, from four to eight inches deep, and about five eighths of an inch in diameter. Like the others, these nests are usually grouped in considerable numbers, very near to one another; sometimes, indeed, they are contiguous. The first admirers of the art of these creatures, the "pioneer ctenizas"—the Italian Pietro Rossi, and the Frenchman Victor Audouin—were struck with this association, so like that of villages; for we do not usually think of spiders without conceiving them as solitary and isolated. But it is evident that these trap-door spiders do not hold that antipathy toward their fellows by race which is the rule in the Arachnidan world. While everywhere else, with this strange race, the association of males and females is only for an instant, and is accomplished by a surprise, the manners of the ctenizas are more gentle and like those of birds. The chief difference is that, while the bird builds a nest for its family, the cteniza has a permanent home in which to accommodate its offspring. The ctenizas behave as if they knew what was to occur. At the time of reproduction, a male is admitted to the residence of the female, and becomes a guest there. The eggs having been laid, the couple appear to watch together over the deposit with the best understanding, and an equal solicitude. But when the young have become large enough, like young birds, they leave the nest and assume their independence without any further concern for parental cares, and the father and mother separate, to resume the freedom of isolation. And when we observe a male in the cell of a female, we are inclined to think that many doors are open to him; for females are numerous and males are rare.

Mr. Traherne Moggridge undertook to obtain a deeper view of the life-secrets of the mason or trap-door spiders. As they work at night, it was not easy to surprise them when active in their labors; but much may be accomplished in the way of discovery by the exercise of patience and sagacity. Mr. Moggridge found it a good plan to follow the spider in building a new abode when its old one had been demolished. It executes its task speedily, without neglecting any detail, as if in obedience to a perfect method. The favorite places are the slopes of terraces and the banks of rivers; choosing a time, if it can, when the ground is moist, it clears away the earth with its claw-rake, and marks out the cylindrical hole. If there are any places in the walls that lack cohesion and where a slide may be anticipated, the animal, as if it were a graduate from a school of engineers, consolidates the parts with silk and weaves in successive layers the pretty satiny texture with which its house is to be adorned. It pursues its task in this way till the determined depth is reached. The tube having been constructed, the mason stretches a little web over the opening, sticking to it such particles of earth as it may find within its reach. A new sheet of silk is stretched over this, and a second layer is formed; and the process is repeated till the trap-door has obtained the requisite thickness. Then it shaves the edges to make the contours even, and the door is finished. If we compare several nests of the same species, we shall notice considerable differences in the merit of the work, from the greatest excellence down to comparative inferiority. Sometimes we find nests with two doors and two vestibules. In the majority of instances of this kind, one of the trap-doors has been condemned. Sometimes the hole is provided with an ascending annex, not opening out upon the surface but provided with an interior door separating a smaller chamber from the main abode. This puts the spider to advantage against an enemy that may have gained access to the main chamber. The ctenizas take a variety of precautions against being discovered. Sometimes the trap-doors are disguised by looking in no way different from the ground around them. In other places they are concealed by means of moss, lichen, grass-blades, bits of straw, or whatever foreign bodies it may be convenient to strew around and over them. The masons are very diligent in their work. If one of them is deprived of his retreat, he will replace it in a night or two. But, notwithstanding their skill in construction, the best observers affirm that young spiders will not abandon a nest when it has become too narrow for them. They have the art of enlarging them so that they shall always be at ease within. The Austrian naturalist, Erber, met in the island of Tinos, in 1868, a previously unknown species. He studied its habits and found that it came out of its nest every evening to make an excursion, but left its door open, fastening it back to some stone or plant-stalk, protecting the entrance by weaving over it a net which it destroyed on its return in the morning.

The trap-door spiders have been seen in many parts of the globe, but usually in countries where a high temperature prevails. They are abundant in the countries around the Mediterranean, and have been observed in the Austral lands and in America. A species of very fair proportions, the Cteniza Californica, lives in California. A living specimen was kept and observed by M. Hippolyte Lucas for four months in the Muséum d'Histoire naturelle. The observer succeeded in opening the door of the cell and presenting the spider with a fly. The cteniza, hungry after a long voyage, seized the fly at the entrance of its burrow, but retired to the back upon the attempt being made to draw it out; and it continued suspicious, even toward its friend. One night, after it had had a few days of good feeding, it sealed the circumference of its door, which it was annoyed to see opened by a stranger, and on the next day a new trap was constructed at a short distance from the former one. Had the creature thought that the new door would be unknown to the person who had disturbed it at the old one? When its last hour was approaching, the California mason crept slowly out from its home, and was afterward picked up dead on the ground at some distance from the spot.

In the world of spiders, as we have seen it under its varying aspects, a fundamental unity of character prevails in essentials, with an attracting diversity in secondary things. While the creatures are highly organized, they are very unequally endowed in fortune, in physical advantages, and in resources to help them in the struggle for existence. Notwithstanding their sagacity, they do not inspire the interest or sympathy that is bestowed upon insects that work in common and form social organizations. In their solitary life they represent individual egotism in its most absolute sense. Yet they are all alike watchful mothers, displaying an unparalleled solicitude for their offspring—a solicitude which we might even call tenderness. While with most other animals the sexual relations promote kindly and social qualities, the relations between male and female spiders are generally very much strained. Yet, as if Nature repelled a rule absolutely without exception, we have witnessed some pleasant instances of union among a few privileged species. The instincts of spiders have revealed themselves in striking forms, while some signs of a higher faculty have also appeared. And does not a being which shows such just appreciation of situations, and can repair damages to its structures in so irreproachable a manner, show evidence of a reasoning faculty? In truth, observation of the acts and faculties of the humblest creatures is not without use in adding to our knowledge of the wonderful phenomena which are the subjects of psychology.—Translated for the Popular Science Monthly from the Revue des Deux Mondes.

 


 
The advance that has taken place in scientific and in all thought is wonderfully illustrated in the history of the authorship of the "Vestiges of Creation." Robert Chambers's connection with the work was well understood in private circles when the book appeared, but was never avowed; and he was obliged to forego a candidacy for public office for fear that the matter would be stirred. This was because there was danger that the house of the Chambers's would be ruined if it became publicly known that one of its members was the author of so pernicious a book. Compare this situation with that of the present, when evolution has become a general scientific fact, exerting its acknowledged influence on religious thought, almost without longer exciting remark!
  1. This spider, whose name translated is the golden-bellied Nephila, has been described in "La Nature," by M. Maurice Maindron, from his observations of it in Java, the Moluccas, and New Guinea. Its nests are quite numerous in Java, and occupied several metres in the forests. They are constructed at an elevation above the ground corresponding with the height of a man's head, and are frequently annoying to persons passing through the wood. M. Maindron found the threads strong enough to pull off his salacko, or cork helmet, whenever it became entangled in them, and hold it suspended in their meshes. It is not unusual for the casual intruder into the nest to carry off the spider on his face, where the animal makes itself perfectly at home, and will promenade at its leisure over your face, shoulders, and arms, and will walk quietly the length of your body, in no seeming hurry to get away.—Editor.