CHAPTER IX.THE SPIDER.

CHAPTER IX.THE SPIDER.ATTEMPTS TO PROCURE SILKEN FILAMENTS FROM SPIDERS.

ATTEMPTS TO PROCURE SILKEN FILAMENTS FROM SPIDERS.

Structures of spiders—Spiders not properly insects, and why—Apparatus for spinning—Extraordinary number of spinnerules—Great number of filaments composing one thread—Réaumur and Leeuwenhoeck’s laughable estimates—Attachment of the thread against a wall or stick—Shooting of the lines of spiders—1. Opinions of Redi, Swammerdam, and Kirby—2. Lister, Kirby, and White—3. La Pluche and Bingley—4. D’Isjonval, Murray, and Bowman—5. Experiments of Mr. Blackwall—His account of the ascent of gossamer—6. Experiments by Rennie—Thread supposed to go off double—Subsequent experiments—Nests, Webs, and Nets of Spiders—Elastic satin nest of a spider—Evelyn’s account of hunting spiders—Labyrinthic spider’s nest—Erroneous account of the House Spider—Geometric Spiders—Attempts to procure silken filaments from Spiders bags—Experiments of M. Bon—Silken material—Manner of its preparations—M. Bon’s enthusiasm—His spider establishment—Spider-silk not poisonous—Its usefulness in healing wounds—Investigation of M. Bon’s establishment by M. Réaumur—His objections—Swift’s satire against speculators and projectors—Ewbank’s interesting observations on the ingenuity of spiders—Mason-spiders—Ingenious door with a hinge—Nest from the West Indies with spring hinge—Raft-building Spider—Diving Water-Spider—Rev. Mr. Kirby’s beautiful description of it—Observations of M. Clerck—Cleanliness of Spiders—Structure of their claws—Fanciful account of them patting their webs—Proceedings of a spider in a steamboat—Addison—His suggestions on the compilation of a “History of Insects.”

Of spiders there are many species; most of them extend their labors no farther than merely to make a web to ensnare and detain their food. But others are known to go beyond this, and spin a bag in the form of a cocoon, for the protection of their eggs, nearly similar to that of the silk-worm.[142]

[142]Don Luis Nee observed on certain trees growing in Chilpancingo, Tixtala in South America, ovate nests of caterpillars, eight inches long, which the inhabitants manufacture into stockings and handkerchiefs.—Annals of Botany, 2d, p. 104.

Modern naturalists do not rank spiders among insects, because they have no antennæ, and no division between the headand shoulders. They breathe by leaf-shaped gills, situated under the belly, instead of spiracles in the sides; and have a heart connected with these. But as spiders are popularly considered insects, it will sufficiently suit our purpose to introduce them here as such.

Spiders are usually classed according to their difference of color, whether black, brown, yellow, &c., or sometimes by the number and arrangement of their eyes: of these organs some possess no fewer than ten, others eight, and others again six[143].

[143]Porter’s “Treatise on the Silk Manufacture,” p. 168.

Some species of spiders are known to possess the power of not merely forming a web, but also of spinning, for the protection of their eggs, a bag somewhat similar in form and substance to the cocoon of the silk-worm. The apparatus by which they construct their ingenious fabrics, is much more complicated than that which is common to the various species of caterpillars. Caterpillars have only two reservoirs for the materials of their silk; but the spider spins minute fibres from fine papillæ, or small nipples placed in the hinder part of its body. These papillæ serve the office of so many wire-drawing machines, from which the silken threadlets are ejected. Spiders, according to the dissections of M. Treviranus, have four principal vessels, two larger and two smaller, with a number of minute ones at their base. Several small tubes branch towards the reservoirs, for carrying to them, no doubt, a supply of the secreted material. Swammerdam describes them as twisted into many coils of an agate color[144]. We do not find them coiled, but nearly straight, and of a deep yellow color. From these, when broken, threads can be drawn out like those spun by the spider, though we cannot draw them so fine by many degrees.

[144]Hill’s Swammerdam, part i. p. 23.

From these little flasks or bags of gum, situated near the apex of the abdomen, and not at the mouth as in caterpillars, a tube originates, and terminates in the external spinnerets, which may be seen by the naked eye in the form of five little teats surrounded by a small circle, as represented in Fig. 8.Plate IV.; this figure shows the garden spider (Epeira diadema) suspended by a thread proceeding from its spinneret.

We have seen that the thread of the silk-worm is composed of two filaments united, but the spider’s thread would appear, from the first view of its five spinnerets, to be quintuple, and in some species which have six teats, so many times more. It is not safe, however, in our interpretations of nature to proceed upon conjecture, however plausible, nor to take anything for granted which we have not actually seen; since our inferences in such cases are almost certain to be erroneous. If Aristotle, for example, had ever looked narrowly at a spider when spinning, he could not have fancied, as he does, that the materials which it uses are nothing but wool stripped from its body. On looking, then, with a strong magnifying glass, at the teat-shaped spinnerets of a spider, we perceive them studded with regular rows of minute bristle-like points, about a thousand to each teat, making in all from five to six thousand. These are minute tubes which we may appropriately termspinnerules, as each is connected with the internal reservoirs, and emits a thread of inconceivable fineness. Fig. 9. represents this wonderful apparatus as it appears in the microscope.

We do not recollect that naturalists have ventured to assign any cause for this very remarkable multiplicity of the spinnerules of spiders, so different from the simple spinneret of caterpillars. To us it appears an admirable provision for their mode of life. Caterpillars neither require such strong materials, nor that their thread should dry as quickly. It is well known in our manufactures, particularly in rope-spinning, that in cords of equal thickness, those which are composed of many smaller ones united are stronger than those spun at once. In the instance of the spider’s thread, this principle must hold still more strikingly, inasmuch as it is composed of fluid materials that require to be dried rapidly, and this drying must be greatlyfacilitated by exposing so many to the air separately before their union, which is effected at about the tenth of an inch from the spinnerets. In Fig. 10.Plate IV. each of the threads shown is represented to contain one hundred minute threads, the whole forming only one of the spider’s common threads. In the figure the threads are, of course, greatly magnified, so that, for the small space represented, the lines are shown as parallel. The threadlets, or filaments as they come from the papillæ, are too fine to be counted with any degree of accuracy, but it is evident that very many are sent forth from each of the larger papillæ. This fact tends to explain the power possessed by the spider of producing threads having different degrees of tenuity. By applying more or less of these papillæ against the place whence it begins its web, the spider joins into one thread the almost imperceptible individual filaments which it draws from its body; the size of this thread being dependent on the number of nipples employed, and regulated by that instinct which teaches the creature to make choice of the degree of exility most appropriate to the work wherein it is about to engage.

Réaumur relates that he has often counted as many as seventy or eighty fibres through a microscope, and perceived that there were yet infinitely more than he could reckon; so that he believed himself to be far within the limit of truth in computing that the tip ofeachof the five papillæ furnished 1000 separate fibres: thus supposing that one slender filament of a spider’s web is made up of 5000 fibres!

Leeuwenhoeck, in one of his extraordinary microscopical observations on a young spider, not bigger than a grain of sand, upon enumerating the threadlets in one of its threads, calculated that it would requirefour millionsof them to be as thick as a hair of his head!

Another important advantage derived by the spider from the multiplicity of its threadlets is, that the thread affords a much more secure attachment to a wall, a branch of a tree, or any other object, than if it were simple; for, upon pressing the spinneret against the object, as spiders always do when they fixa thread, the spinnerules are extended over an area of some diameter, from every hair’s breadth of which a strand, as rope-makers term it, is extended to compound the main cord. Fig. 11.Plate IV. exhibits, magnified, this ingenious contrivance. Those who may be curious to examine it, will see it best when the line is attached to any black object, for the threads, being whitish, are, in otherwise, not so easily perceived.

Shooting of the lines.—It has long been considered a curious though difficult investigation, to determine in what manner spiders, seeing that they are destitute of wings, transport themselves from tree to tree, across brooks, and frequently through the air itself, without any apparent starting point. On looking into the authors who have treated upon this subject, it is surprising how little there is to be met with that is new, even in the most recent. Their conclusions, or rather their conjectural opinions, are, however, worthy of notice;for by unlearning error, we the more firmly establish truth.

1. One of the earliest notions upon this subject is that of Blancanus, the commentator on Aristotle, which is partly adopted by Redi, by Henricus Regius of Utrecht, by Swammerdam[145], by Lehmann, as well as by Kirby and Spence[146]. “The spider’s thread,” says Swammerdam, “is generally made up of two or more parts, and after descending by such a thread, it ascends by one only, and is thus enabled to waft itself from one height or tree to another, even across running waters; the thread it leaves loose behind it being driven about by the wind, and so fixed to some other body.” “I placed,” says Kirby, “the large garden spider (Epeira diadema) upon a stick about a foot long, set upright in a vessel containing water.... It let itself drop, not by a single thread, but bytwo, each distant from the other about the twelfth of an inch, guided, as usual, by one of its hind feet, and that one apparently smaller than the other. When it had suffered itself to descend nearly to the surface of the water, it stopped short, and by some means, which I could not distinctly see, broke off, close to the spinners, the smallest thread, which still adhering by the other end tothe top of the stick, floated in the air, and was so light as to be carried about by the slightest breath. On approaching a pencil to the loose end of this line, it did not adhere from mere contact. I, therefore, twisted it once or twice round the pencil, and then drew it tight. The spider, which had previously climbed to the top of the stick, immediately pulled at it with one of its feet, and finding it sufficiently tense, crept along it, strengthening it as it proceeded by another thread, and thus reached the pencil.”

[145]Swammerdam, part i. p. 24.[146]Intr. vol. i. p. 415.

[145]Swammerdam, part i. p. 24.

[146]Intr. vol. i. p. 415.

1. “We have repeatedly witnessed this occurrence,” says Mr. Rennie, “in the fields, and when spiders were placed for experiment, as Kirby has described; but we very much doubt that the thread broken is ever intended as a bridge cable, or that it would have been so used in that instance, had it not been artificially fixed and again accidentally found by the spider. According to our observations, a spider never for an instant, abandons, the thread which she dispatches in quest of an attachment, but uniformly keeps trying it with her feet, in order to ascertain its success. We are, therefore, persuaded, that when a thread is broken in the manner above described, it is because it has been spun too weak, and spiders may often be seen breaking such threads in the process of netting their webs.”

The plan, besides, as explained by these distinguished writers, would more frequently prove abortive than successful, from the cut thread not being sufficiently long. They admit, indeed, that spiders’ lines are often found “a yard or two long, fastened to twigs of grass not a foot in height.... Here, therefore, some other process must have been used[147].”

[147]Kirby and Spence, vol. i. Intr. p. 416.

2. The celebrated English naturalist, Dr. Lister, whose treatise upon the native spiders of that country, has been the basis of every subsequent work on the subject, maintains that “some spiders shoot out their threads in the same manner that porcupines do their quills[148]; that whereas the quills of the latter are entirely separated from their bodies, when thus shot out, the threads of the former remain fixed to their anus, as the sun’s rays to its body[149].” A French periodical writer goes a little farther, and says, that spiders have the power of shooting out threads,and directing them at pleasure towards a determined point, judging of the distance and position of the objectby some sense of which we are ignorant[150]. Kirby also says, that he once observed a small garden spider (Aranea reticulata) “standing midway on a long perpendicular fixed thread, and an appearance caught” his “eye, of what seemed to be the emission of threads.” “I,” therefore, he adds, “moved my arm in the direction in which they apparently proceeded, and, as I had suspected, a floating thread attached itself to my coat, along which the spider crept. As this was connected with the spinners of the spider, it could not have been formed” by breaking a “secondary thread[151].” Again, in speaking of the gossamer-spider, he says, “it first extends its thigh, shank, and foot, into a right line, and then, elevating its abdomen till it becomes vertical,shoots its threadinto the air, and flies off from its station[152].”

[148]Porcupines do not shoot out their quills, as was once generally believed.[149]Lister, Hist. Animalia Angliæ, 4to. p. 7.[150]Phil. Mag. ii. p. 275.[151]Vol. i. Intr. p. 417.[152]Ibid. ii. p. 339.

[148]Porcupines do not shoot out their quills, as was once generally believed.

[149]Lister, Hist. Animalia Angliæ, 4to. p. 7.

[150]Phil. Mag. ii. p. 275.

[151]Vol. i. Intr. p. 417.

[152]Ibid. ii. p. 339.

Another distinguished naturalist, Mr. White of Selborne, in speaking of the gossamer-spider, says, “Every day in fine weather in autumn do I see these spiders shooting out their webs, and mounting aloft: they will go off from the finger, if you take them into your hand. Last summer, one alighted on my book as I was reading in the parlor; ran to the top of the page, andshooting out a web, took its departure from thence. But what I most wondered at, was, that it went off with considerable velocity in a place where no air was stirring; and I am sure I did not assist it with my breath[153].”

[153]Nat. Hist. of Selborne, vol. i. p. 327.

“Having so often witnessed,” says Mr. Rennie, “the thread set afloat in the air by spiders, we can readily conceive the way in which those eminent naturalists were led to suppose it to be ejected by some animal force acting like a syringe; but as the statement can be completely disproved by experiment, we shall only at present ask, in the words of Swammerdam—‘how can it be possible that a thread so fine and slender should be shot out with force enough to divide and pass through the air?—is it not rather probable that the air would stop its progress, and so entangle it and fit it to perplex the spider’s operations[154]?’”The opinion, indeed, is equally improbable with another suggested by Dr. Lister, that the spider can retract her thread within the abdomen, after it has been emitted[155]. De Geer[156]very justly joins Swammerdam in rejecting both of these fancies, which, in our own earlier observations upon spiders, certainly struck us as plausible and true. There can be no doubt, indeed, that the animal has a voluntary power of permitting the material to escape, or stopping it at pleasure, but this is not projectile.

[154]Book of Nature, part i. p. 25.[155]Hist. Anim. Anglæ, 4to.[156]Mémoires, vol. vii. p. 189.

[154]Book of Nature, part i. p. 25.

[155]Hist. Anim. Anglæ, 4to.

[156]Mémoires, vol. vii. p. 189.

3. “There are many people,” says the Abbé de la Pluche, “who believe that the spider flies when they see her pass from branch to branch, and even from one high tree to another; but she transports herself in this manner; and places herself upon the end of a branch, or some projecting body, and there fastens her thread; after which, with her two hind feet, she squeezes her dugs (spinnerets), and presses out one or more threads of two or three ells in length, which she leaves to float in the air till it be fixed to some particular place[157].” Without pretending to have observed this, Swammerdam says, “I can easily comprehend how spiders, without giving themselves any motion, may, by only compressing their spinnerets, force out a thread, which being driven by the wind, may serve to waft them from place to place[158].” Others, proceeding upon a similar notion, give a rather different account of the matter. “The spider,” says Bingley, “fixes one end of a thread to the place where she stands, and then with her hind pawsdraws outseveral other threads from the nipples, which, being lengthened out and driven by the wind to some neighboring tree or other object, are by their natural clamminess fixed to it[159].”

[157]Spectacle de la Nature, vol. i.[158]Book of Nature, pt. i. p. 25.[159]Animal Biography, vol. iii. p. 475, 3d edition.

[157]Spectacle de la Nature, vol. i.

[158]Book of Nature, pt. i. p. 25.

[159]Animal Biography, vol. iii. p. 475, 3d edition.

Observation gives some plausibility to the latter opinion, as the spider always actively uses her legs, though not to draw out the thread, but ascertain whether it has caught upon any object. The notion of her pressing the spinneret with her feetmust be a mere fancy; at least it is not countenanced by anything which we have observed.

4. An opinion much more recondite is mentioned, if it was not started, by M. D’Isjonval, that the floating of the spider’s thread is electrical. “Frogs, cats, and other animals,” he says, “are affected by natural electricity, and feel the change of weather; but no other animal more than myself and spiders.” In wet and windy weather he accordingly found that they spun very short lines, “but when a spider spins a long thread, there is a certainty of fine weather for at least ten or twelve days afterwards[160].” A periodical writer, who signs himself Carolan[161], fancies that in darting out her thread the spider emits a stream of air, or some subtle electric fluid, by which she guides it as if by magic.

[160]Brez, Flore des Insectophiles. Notes, Supp. p. 134.[161]Thomson’s Ann. of Philosophy, vol. iii. p. 306.

[160]Brez, Flore des Insectophiles. Notes, Supp. p. 134.

[161]Thomson’s Ann. of Philosophy, vol. iii. p. 306.

A living writer (Mr. John Murray) whose learning and skill in conducting experiments give no little weight to his opinions, has carried these views considerably farther. “The aëronautic spider,” he says, “can propel its thread both horizontally and vertically, and at all relative angles,in motionless airand in anatmosphere agitated by winds; nay more, the aërial traveller can even dart its thread, to use a nautical phrase, in the ‘wind’s eye.’ My opinion and observations are based on many hundred experiments.... The entire phenomena are electrical. When a thread is propelled in a vertical plane, it remains perpendicular to the horizontal plane always upright, and when others are projected at angles more or less inclined, their direction is invariably preserved; the threads never intermingle, and when a pencil of threads is propelled, it ever presents the appearance of a divergent brush. These are electrical phenomena, and cannot be explained but on electrical principles.”

“In clear, fine weather, the air is invariably positive; and it is precisely in such weather that the aëronautic spider makes its ascent most easily and rapidly, whether it be in summer or winter.” “When the air is weakly positive, the ascent of thespider will be difficult, and its altitude extremely limited, and the threads propelled will be but little elevated above the horizontal plane. When negative electricity prevails, as in cloudy weather, or on the approach of rain, and the index of De Saussure’s hygrometer rapidly advancing towards humidity, the spider is unable to ascend[162].”

[162]Loudon’s Mag. of Nat. Hist., vol. i. p. 322.

Mr. Murray tells us, that “when a stick of excited sealing-wax is brought near the thread of suspension, it is evidently repelled; consequently, the electricity of the thread is of a negative character,” while “an excited glass tube brought near, seemed to attract the thread, and with it the aëronautic spider[163].” His friend, Mr. Bowman, further describes the aërial spider as “shooting out four or five, often six or eight, extremely fine webs several yards long, which waved in the breeze, diverging from each other like a pencil of rays.” One of them “had two distinct and widely diverging fasciculi of webs,” and “a line uniting them would have been at right angles to the direction of the breeze[164].”

[163]Experim. Researches in Nat. Hist., p. 136.[164]Mag. Nat. Hist. vol. i. p. 324.

[163]Experim. Researches in Nat. Hist., p. 136.

[164]Mag. Nat. Hist. vol. i. p. 324.

“Such is the chief evidence in support of the electrical theory,” says Mr. Rennie; “but though we have tried these experiments, we have not succeeded in verifying any one of them. The following statements of Mr. Blackwall come nearer our own observations.

5. ‘Having procured a small branched twig,’ says Mr. Blackwall, ‘I fixed it upright in an earthen vessel containing water, its base being immersed in the liquid, and upon it I placed several of the spiders which produce gossamer. Whenever the insects thus circumstanced were exposed to a current of air, either naturally or artificially produced, they directly turned the thorax towards the quarter whence it came, even when it was so slight as scarcely to be perceptible, and elevating the abdomen, they emitted from their spinners a small portion of glutinous matter, which was instantly carried out in a line, consisting of four finer ones, with a velocity equal, or nearlyso, to that with which the air moved, as was apparent from observations made on the motion of detached lines similarly exposed. The spiders, in the next place, carefully ascertained whether their lines had become firmly attached to any object or not, by pulling at them with the front pair of legs; and if the result was satisfactory, after tightening them sufficiently, they made them pass to the twig; then discharging from their spinners, which they applied to the spot where they stood, a little more of their liquid gum, and committing themselves to these bridges of their own constructing, they passed over them in safety, drawing a second line after them, as a security in case the first gave way, and so effected their escape.

‘Such was invariably the result when spiders were placed where the air was liable to be sensibly agitated: I resolved, therefore, to put a bell-glass over them; and in this situation they remained seventeen days, evidently unable to produce a single line by which they could quit the branch they occupied, without encountering the water at its base; though, on the removal of the glass, they regained their liberty with as much celerity as in the instances already recorded.

‘This experiment, which, from want of due precaution, has misled so many distinguished naturalists, I have tried with several geometric spiders, and always with the same success[165].’”

[165]Linn. Trans., vol. xv. p. 456.

Mr. Blackwall, from subsequent experiments, says he is “confident in affirming, that in motionless air, spiders have not the power of darting their threads even through the space of half an inch[166].” The following details are given in confirmation of this opinion. Mr. Blackwall observed, the 1st of Oct., 1826, a little before noon, with the sun shining brightly, no wind stirring, and the thermometer in the shade ranging from 55°.5 to 64°, a profusion of shining lines crossing each other at every angle, forming a confused net-work, covering the fields and hedges, and thickly coating his feet and ankles, as he walked across a pasture. He was more struck with the phenomenon because on the previous day a strong gale of wind hadblown from the south, and as gossamer is only seen in calm weather, it must have been all produced within a very short time.

[166]Mag. Nat. Hist., vol. ii. p. 397.

“What more particularly arrested my attention,” says Mr. Blackwall, “was the ascent of an amazing quantity of webs of an irregular, complicated structure, resembling ravelled silk of the finest quality, and clearest white; they were of various shapes and dimensions, some of the largest measuring upwards of a yard in length, and several inches in breadth in the widest part; while others were almost as broad as long, presenting an area of a few square inches only.

“These webs, it was quickly perceived, were not formed in the air, as is generally believed,but at the earth’s surface. The lines of which they were composed, being brought into contact by the mechanical action of gentle airs, adhered together, till, by continual additions, they were accumulated into flakes or masses of considerable magnitude, on which the ascending current, occasioned by the rarefaction of the air contiguous to the heated ground, acted with so much force as to separate them from the objects to which they were attached, raising them in the atmosphere to a perpendicular height of at least several hundred feet. I collected a number of these webs about mid-day, as they rose; and again in the afternoon, when the upward current had ceased, and they were falling; but scarcely one in twenty contained a spider: though, on minute inspection, I found small winged insects, chieflyaphides, entangled in most of them.

“From contemplating this unusual display of gossamer, my thoughts were naturally directed to the animals which produced it, and the countless myriads in which they swarmed almost created as much surprise as the singular occupation that engrossed them. Apparently actuated by the same impulse, all were intent upon traversing the regions of air;accordingly, after gaining the summits of various objects, as blades of grass, stubble, rails, gates, &c., by the slow and laborious process of climbing, they raised themselves still higher by strengthening their limbs; and elevating the abdomen, by bringing it from the usual horizontal position into one almostperpendicular, they emitted from their spinning apparatus a small quantity of the glutinous secretion with which they construct their webs. This viscous substance being drawn out by the ascending current of rarefied air into fine lines several feet in length, was carried upward, until the spiders, feeling themselves acted upon with sufficient force in that direction, quitted their hold of the objects on which they stood, and commenced their journey by mounting aloft.

“Whenever the lines became inadequate to the purpose for which they were intended, by adhering to any fixed body, they were immediately detached from the spinners and so converted into terrestrial gossamer, by means of the last pair of legs, and the proceedings just described were repeated; which plainly proves that these operations result from a strong desire felt by the insects to effect an ascent[167].” Mr. Blackwall has recently read a paper (still unpublished) in the Linnæan Society, confirmatory of his opinions.

[167]Linn. Trans., vol. xv. p. 453.

6. “Without going into the particulars,” says Mr. Rennie, “of what agrees or disagrees in the above experiments with our own observations, we shall give a brief account of what we have actually seen in our researches. So far as we have determined, then, all the various species of spiders, how different soever the form of their webs may be, proceed in the circumstance of shooting their lines precisely alike; but those which we have found the most manageable in experimenting, are the small gossamer spider (Aranea obtextrix,Bechstein), known by its shining blackish-brown body and reddish-brown semi-transparent legs; but particularly the long-bodied spider (Tetragnatha extensa,Latr.), which varies in color from green to brownish or grey—but has always a black line along the belly, with a silvery white or yellowish one on each side. The latter is chiefly recommended by being a very industrious and persevering spinner, while its movements are easily seen, from the long cylindrical form of its body and the length of its legs.

“We placed the above two species with five or six others, including the garden, the domestic, and the labyrinthic spiders,in empty wine-glasses, set in tea-saucers filled with water, to prevent their escape. When they discovered, by repeated descents from the brims of the glasses, that they were thus surrounded by a wet ditch, they all set themselves to the task of throwing their silken bridges across. For this purpose they first endeavored to ascertain in what direction the wind blew, or rather (as the experiment was made in our study) which way any current of air set,—by elevating their armsas we have seen sailors do in a dead calm. But, as it may prove more interesting to keep to one individual, we shall first watch the proceedings of the gossamer spider.

“Finding no current of air on any quarter of the brim of the glass, it seemed to give up all hopes of constructing its bridge of escape, and placed itself in the attitude of repose;but no sooner did we produce a stream of air, by blowing gently towards its position, than, fixing a thread to the glass, and laying hold of it with one of its feet, by way of security, it placed its body in a vertical position, with its spinnerets extended outwards; and immediately we had the pleasure of seeing a thread streaming out from them several feet in length, on which the little aëronaut sprung up into the air. We were convinced, from what we thus observed, that it was the double or bend of the thread which was blown into the air; and we assigned as a reason for her previously attaching and drawing out a thread from the glass, the wish to give the wind apoint d’appui—something upon which it might have apurchase, as a mechanic would say of a lever. The bend of the thread, then, on this view of the matter, would be carried out by the wind,—would form the point of impulsion,—and, of course, the escape bridge would be an ordinary line doubled.”

Such is the opinion of Mr. Rennie, which is strongly corroborated by what has been said by M. Latreille—than whom no higher authority could be given. “When the animal,” says he, “desires to cross a brook, she fixes to a tree or some other object one of the ends of her first threads, in order that the wind or a current of air may carry the other beyond the obstacle[168];”and as one end is always attached to the spinnerets, he must mean that the double of the thread flies off. In his previous publications, however, Latreille had contented himself with copying the statement of Dr. Lister. “In order to ascertain the fact,” says Mr. Rennie, “and put an end to all doubts, we watched, with great care and minuteness, the proceedings of the long-bodied spider above mentioned, by producing a stream of air in the same manner, as it perambulated the brim of the glass. It immediately, as the other had done, attached a thread and raised its body perpendicularly, like a tumbler standing on his hands with his head downwards; but we looked in vain for this thread bending, as we had at first supposed, and going off double. Instead of this it remained tight, while another thread, or what appeared to be so, streamed off from the spinners, similar to smoke issuing through a pin-hole, sometimes in a line, and sometimes at a considerable angle, with the first, according to the current of the air,—the first thread, extended from the glass to the spinnerets, remaining all the while tight drawn in a right line. It further appeared to us, that the first thread proceeded from the pair of spinnerets nearest the head, while the floating thread came from the outer pair,—though it is possible in such minute objects we may have been deceived. That the first was continuous with the second, without any perceptible joining, we ascertained in numerous instances, by catching the floating line and pulling it tight, in which case the spider glides along without attaching another line to the glass; but if she have to coil up the floating line to lighten it, as usually happens, she gathers it into a packet and glues the two ends tight together. Her body, while the floating line streamed out, remained quite motionless, but we distinctly saw the spinnerets not only projected, as is always done when a spider spins, but moved in the same way as an infant moves its lips when sucking. We cannot doubt, therefore, that this motion is intended to emit (if eject or project be deemed words too strong), the liquid material of the thread; at the same time,we are quite certain that it cannot throw out a single inch of threadwithout the aid of a current of air. A long-bodied spider will thus throw out in succession as many threads as we please, by simply blowing towards it; but not one where there is no current, as under a bell-glass, where it may be kept till it die, without being able to construct a bridge over water of an inch long. We never observed more than one floating thread produced at the same time; though other observers mention several.

[168]——“L’un des bouts de ces premiers fils, afin que le vent ou un courant d’air pousse l’autre extrémité de l’un d’eux au delà de l’obstacle.”—Dict. Classique d’Hist. Nat., vol. i. p. 510.

“The probable commencement, we think, of the floating line, is by the emission of little globules of the glutinous material to the points of the spinnerules—perhaps it may be dropped from them, if not ejected, and the globules being carried off by the current of air, drawn out into a thread. But we give this as only a conjecture, for we could not bring a glass of sufficient power to bear upon the spinnerules at the commencement of the floating line.

“In subsequent experiments we found, that it was not indispensable for the spider to rest upon a solid body when producing a line, as she can do so while she is suspended in the air by another line. When the current of air also is strong, she will sometimes commit herself to it by swinging from the end of the line. We have even remarked this when there was scarcely a breath of air.

“We tried another experiment. We pressed pretty firmly upon the base of the spinnerets, so as not to injure the spider, blowing obliquely over them; but no floating line appeared. We then touched them with a pencil and drew out several lines an inch or two in length, upon which we blew in order to extend them, but in this also we were unsuccessful, as they did not lengthen more than a quarter of an inch. We next traced out the reservoirs of a garden-spider (Epeira diadema), and immediately taking a drop of the matter from one of them on the point of a fine needle, we directed upon it a strong current of air, and succeeded in blowing out a thick yellow line, as we might have done with gum-water, of about an inch and a half long.

“When we observed our long-bodied spider eager to throw aline by raising up its body, we brought within three inches of its spinnerets an excited stick of sealing-wax, of which it took no notice, nor did any thread extend to it, not even when brought almost to touch the spinnerets. We experienced the same want of success with an excited glass rod; and indeed had not anticipated any other result, as we have never observed that either these attract or repel the floating threads, as Mr. Murray has seen them do; nor have we ever noticed the end of a floating thread separated into its component threadlets and diverging like a brush, as he and Mr. Bowman describe (See Fig. 11.). It may be proper to mention that Mr. Murray, in conformity with his theory, explains the shooting of lines in a current of air by the electric state produced by motion in consequence of the mutual friction of the gaseous particles. But this view of the matter does not seem to affect our statements.”

Nests, Webs, and Nets of Spiders.—“The neatest,” says Mr. Rennie, “though the smallest spider’s nest which we have seen, was constructed in the chink of a garden-post, which we had cut out the previous summer in getting at the cells of a carpenter-bee. The architect was one of the larger hunting-spiders, erroneously said by some naturalists to be incapable of spinning. The nest in question was about two inches high, composed of a very close satin-like texture. There were two parallel chambers placed perpendicularly, in which position also the inhabitant reposed there during the day, going, as we presume, only abroad to prey during the night. But the most remarkable circumstance was, that the openings (two above and two below) were so elastic, that they shut closely together. We observed this spider for several months, but at last it disappeared, and we took the nest out under the notion that it might contain eggs; but found none, and therefore concluded that it was only used as a day retreat.” The account which Evelyn has given of these hunting spiders is so interesting that we must transcribe it.

“Of all sorts of insects,” says he, “none have afforded me more divertisement than thevenatores(hunters), which are a sort oflupi(wolves) that have their dens in ruggedwalls and crevices of our houses; a small brown and delicately-spotted kind of spiders, whose hinder legs are longer than the rest. Such I did frequently observe at Rome, which, espying a fly at three or four yards distance, upon the balcony where I stood, would not make directly to her,but crawl under the rail, till being arrived to the antipodes, it would steal up, seldom missing its aim; but if it chanced to want anything of being perfectly opposite, would, at first peep, immediately slide down again,—till taking better notice, it would come the next time exactly upon the fly’s back: but if this happened not to be within a competent leap, then would this insect move so softly, as the very shadow of the gnomon seemed not to be more imperceptible, unless the fly moved; and then would the spider move also in the same proportion, keeping that just time with her motion, as if the same soul had animated both these little bodies; and whether it were forwards, backwards, or to either side, without at all turning her body, like a well-managed horse: but if the capricious fly took wing and pitched upon another place behind our huntress, then would the spider whirl its body so nimbly about, as nothing could be imagined more swift: by which means she always kept the head towards her prey, though, to appearance, as immoveable as if it had been a nail driven into the wood, till by that indiscernible progress (being arrived within the sphere of her reach) she made a fatal leap, swift as lightning, upon the fly, catching him in the pole, where she never quitted hold till her belly was full, and then carried the remainder home.”

One feels a little sceptical, however, when he adds, “I have beheld theminstructing their young ones how to hunt, which they would sometimes discipline for not well observing; but when any of the old ones did (as sometimes) miss a leap,they would run out of the field and hide themselves in their crannies, as ashamed, and haply not to be seen abroad for four or five hours after; for so long have I watched the nature of this strange insect, the contemplation of whose so wonderful sagacity and address has amazed me; nor do I find in any chase whatsoever more cunning and stratagem observed. Ihave found some of these spiders in my garden, when the weather, towards spring, was very hot, but they are not so eager in hunting as in Italy[169].”

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