The Atlantic Monthly/Volume 18/Number 106/How my New Acquaintances spin
HOW MY NEW ACQUAINTANCES SPIN.
The strictly professional man may have overcome his natural aversion to some of the most interesting objects of his study, such as snakes, and toads, and spiders, and vermin of all kinds; but people in general have always required that any attempt to force such abominations upon their notice should be preceded by a more or less elaborate and humble acknowledgment of their hideous aspect, their ferocious disposition, their dark and bloody deeds, and the utter impossibility of their conducing in any way to human comfort and convenience.
But, while admitting the truth of much that has been thus urged against spiders as a class, I must decline, or at least defer, conforming to custom in speaking of the particular variety which we are about to consider, and I believe that it will need only a glance at the insect and its silk, and a brief notice of its habits, to justify my indisposition to follow the usual routine.
Without apology, then, I shall endeavor to show that in the structure, the habits, the mode of growth, and, above all, in the productions of this spider are to be found subjects worthy the attention of every class of minds; for to the naturalist is exhibited a species which, though not absolutely new to science, was never seen nor heard of by Professor Agassiz till the spring of 1865, and which is so narrowly circumscribed in its geographical distribution that, so far as I can ascertain, it was never observed by Hentz,—a Southern entomologist, who devoted himself particularly to spiders,—and is met with only upon a few low, marshy islands on the coast of South Carolina, and perhaps of other Southern States. Its habits, too, are so interesting, and so different in many respects from those recorded of other species, that the observer of living creatures has here an abundant opportunity, not only for increasing his own knowledge, but for enlarging the domain of science. And this more especially in America; for while, in England, Blackwall and others have been laboring for more than thirty years, spiders seem to have received little attention on this side of the Atlantic.
We have now, moreover, in our observation of these insects, an incentive of sovereign effect, namely, the hope of increasing our national wealth; for to the practical man, to the manufacturer and the mechanic, is offered a new silken material which far surpasses in beauty and elegance that of the silk-worm, and which, however small in quantity at present, demands some attention in view of the alarming decrease in the silk crops of Europe. This material is obtained in a manner entirely new,—not, as with the worm, by unwinding the cocoons, nor yet, as might be suggested for the spider, by unravelling the web, but by drawing or winding or reeling directly from the body of the living insect, even as you would milk a cow, or, more aptly, as wire is pulled through a wire-drawing machine.
To the admirer of the beautiful and perfect in nature is presented a fibre of absolute smoothness, roundness, and finish, the colors of which resemble, and in the sunlight even excel in brilliancy those of the two precious metals, silver and gold; while the moralist who loves to illustrate the workings of God's providence in bringing forth good out of evil, by comparing the disgusting silk-worm with its beautiful and useful product, may now enforce the lesson by the still more striking contrast between this silk and the loathed and hated spider.
The statesman who, after a four years' war, sees few indications of a better spirit on the part of the South, and is almost ready to exclaim, "Can any good thing come out of Nazareth?" may now perhaps discern a spot, small indeed, but brilliant, on the very edge of the dark Carolina cloud; and it may not be too much to hope that, in course of time, the cords of our spider's golden and silver silk may prove potent bonds of union with the first of the rebellious States.
As to the mathematician who believes in the inborn tendency of mankind to variation and imperfection, and holds up to us, as shining examples of mathematical accuracy, the work of certain insects, and who—since Professor Wyman has shown that the hexagonal form of the bee's cell is not of original design, but rather the necessary result of difficulties met and overcome in the most economical manner, though by no means always with perfect exactness and uniformity—has fallen back upon the ancient and still prevalent belief in the precise construction of the spider's web, (which, as will be seen, really displays it no more than does the bee's cell,)—to this disappointed man of geometry and figures is now offered the alternative of either finding a new and truer illustration, or of abandoning his position entirely.
Let us, then, wait till we have seen this spider and heard his story. His story! That reminds me of another class which may possibly be represented among my readers, and whose members, in the contemplation of the domestic economy of these insects, will, I fear, discover many and weighty arguments in favor of the various opinions entertained by the advocates of Woman's Rights; for here is a community in which the females not only far exceed the males in number, but present so great a contrast to them in size and importance, that, but for absolute proof, they never would be regarded as belonging to the same species.
Here, then, is a life-size picture of our spider and of—I was about to say, his partner; but in truth it is she who is the spider, and he is only her partner. Such is the real physical, and, so to speak, mental superiority of the female, that, even if we insist upon the legal equality at least of the masculine element, we can do so only in name, and will find it hard to avoid speaking of him as the male of the Nephila plumipes, thus tacitly admitting her as the truer representative of the species. Their relative size and appearance are shown by the figures; but it may be added that she is very handsome; the fore part of her body, which, being composed of the head and chest soldered together, is termed cephalothorax, is glossy-black and covered, except in
Fig. 1. Male and Female Nephila plumipes.spots, with white hairs; she has also upon six of her legs one or two brushes of black hairs;—while he is an insignificant-looking insect of a dull-brown color and half-starved look, with only a few scattered bristles upon his slender limbs. He does nothing for himself, leaving her to make the web and provide the food, and even to carry him on her back when removal is necessary; but she makes up for the imposition by keeping him on short allowance and at a respectful distance, excepting when the impregnation of her eggs is necessary; and even then she is mistress of the situation, and, etiam in amoribus sæva, may afterward eat him up. But of this contrast between the two sexes, of their functions and their relations to each other, more hereafter. It is sufficient to observe that, when this spider is mentioned, and the sex is not specified, the female is always referred to.
When, where, and how was this spider discovered? and why is it that we have never heard of it before? To answer these questions, we must go back three years, to the 19th of August, 1863, and to the camp of the Fifty-fifth Regiment of Massachusetts Volunteers, on a desolate island a little south from the harbor of Charleston, South Carolina, and in sight of the fortress which Gillmore had just begun to strengthen by the addition of tons of Union shot and shell, till, from tolerably strong masonry, its walls became solid earthworks which nothing could pierce or greatly injure. There, at the north end of Folly Island,—scarce wider than our camp at that point, and narrower than the magnificent beach which, at low tide, afforded ample space for the battalion drill,—I found in a tree a very large and handsome spider, whose web was at least three feet in diameter.
Glad enough to meet with anything new, and bearing in mind the interest with which, when a boy, I had watched and recorded the operations of our common house and hunting spiders, I entangled him—I didn't then know it was her, so let it pass—in the web, and carried it to my tent. The insect was very quiet, and did not attempt to escape; but presently, after crawling slowly along my sleeve, she let herself down to the floor, taking first the precaution, after the prudent fashion of most spiders, to attach to the point she left a silken line, which, as she descended, came from her body. Rather than seize the insect itself, I caught the thread and pulled. The spider was not moved, but the line readily drew out, and, being wound upon my hands, seemed so strong that I attached the end to a little quill, and, having placed the spider upon the side of the tent, lay down on my couch and turned the quill between my fingers at such a rate that in one minute six feet of silk were wound upon it. At the end of an hour and a half I estimated, with due allowance for stop-pages, that I had four hundred and fifty feet, or one hundred and fifty yards, of the most brilliant and beautiful golden silk I had ever seen.
During all this operation the spider had remained perfectly quiet, but finally put an end to my proceedings by grasping the line with the tip of one of her hind legs so that it snapped. I was tired, however, and contented myself with the quantity already obtained, which now formed a raised band of gold upon the quill. This specimen is now in my possession, but has been removed from the quill to ascertain its weight, which is one third of a grain.
It is worthy of notice, perhaps, that in all this was involved no new fact, but only a happy deduction from one known ages ago; namely, that a spider, when dropping, leaves her line attached, and so allows it to be drawn from her body. Nothing was more natural than to simply reverse the position of the fixed point, and, instead of letting the spider go away from the end of her line, to take the end of her line away from her. So natural, indeed, did it seem, that my gratification at having been (as was then supposed) the first to do it was, on reflection, mixed with surprise that no one had ever thought of it before, and I am very glad to find that at least four individuals have, within the last century, pulled silk out of a spider, though of these only one, whose researches I hope to make known, regarded the matter as anything more than a curious experiment.
I had never before seen such a spider, nor even paid attention to any geometrical species; though one large black and yellow variety is, or used to be, common enough in our fields at the North. Neither had I ever heard of such a method of obtaining silk. But though my first specimen was not preserved, and a second was never seen on Folly Island, yet I was so impressed with its size and brilliant colors, and especially with the curious brushes of black hairs on its legs, that when, during the following summer, another officer described to me a great spider which was very common on Long Island, where he was stationed, I knew it was the same, and told him what I had done the year before, adding that I was sure something would come of it in time.
With leisure and many spiders at his command, this officer improved upon my suggestion, by substituting for my quill turned in the fingers a wooden cylinder worked by a crank, and by securing, at a proper distance, (between pins, I think,) one or more spiders, whose threads were guided between pins upon the cylinder. He thus produced more of the silk, winding it upon rings of hard rubber so as to make very pretty ornaments. With this simple machine I wound the silk in two grooves cut on a ring of hard rubber and parallel except at one point, where they crossed so as to form a kind of signet. Another officer now suggested and put in operation still another improvement, in the shape of the "gear-drill-stock" of our armorer's chest. This, being a machine for drilling iron, was rough in its construction and uneven in its action, but, having cog-wheels, a rapid and nearly steady motion could be given to its shaft. To this shaft he attached a little cross of rubber, and covered it with silk, which was of a silver-white color instead of golden-yellow, as in other cases. The difference in color was then supposed to depend upon individual peculiarities, but the true explanation will be given farther on. With this gear-drill-stock, upon a larger ring, one inch in diameter and three eighths of an inch in width, in a groove upon its periphery one fourth of an inch in width, and across the sides of the ring in two directions, I wound three thousand four hundred and eighty-four yards, or nearly two miles, of silk. The length was estimated by accurately determining the different dimensions of the ring where wound upon, and multiplying by this the number of revolutions of the cylinder per minute (170), and this product again by the number of minutes of actual winding (285), deducting from the gross time of winding (about nine hours) each moment of stoppage for any cause.
This was late in the fall of 1864, and, our specimens being sent home, further experiments, and even thoughts upon the subject, were prevented by the expedition against the Charleston and Savannah Railroad, and the many changes of station that followed the disastrous battle of Honey Hill. But, when I was at the North in February, 1865, a friend expressed to me his confident belief that this new silken product could be made of practical utility, and advised me to make inquiries on the subject. So, before presenting it to the scientific societies, I tested the strength of the silk by attaching to a fixed point one end of a thread one four-thousandth of an inch in diameter, and tying the other end upon the arm of an accurate balance: weights were then dropped in to the amount of fifty-four grains before the line was broken. By a calculation from this, a solid bar of spider's silk, one inch in diameter, would sustain a weight of more than seventy tons; while a similar bar of steel will sustain only fifty-six, and one of iron twenty-eight tons. The specimens were then exhibited to Professors Wyman, Agassiz, and Cooke, of Harvard University, to all of whom the species of spider was unknown, though Professor Wyman has since found a single specimen among some insects collected at the South; while to them as well as to the silk-manufacturers the idea of reeling silk directly from a living insect was entirely new. The latter, of course, wished to see a quantity of it before pronouncing upon its usefulness. So most of my furlough was spent in making arrangements for securing a number of the spiders, and reeling their silk during the coming summer. These comprised six light wooden boxes with sliding fronts, each eighteen inches wide and high and one foot deep, and containing six tin trays one above another, each of which, again, held twenty-four square paper boxes two and a half inches in diameter, and with lids closed by an elastic. Into these the spiders were to be put for transportation. Then I had made a costly machine for reeling the silk, which, however, proved of no practical value.
In March, with these and other real or fancied adjuvants, (some of which proved even less useful and trustworthy than the machine,) but, above all, with a determination to put this matter to the test of actual experiment, I rejoined the regiment at Charleston, which had just fallen into our hands. It was not until April, however, that we were so situated that I could make any attempt to get spiders. Of course it was not expected that the full-grown ones should be found at that season, but the eggs or young should be abundant where the spiders had been in the summer.
Charleston stands upon the extremity of a narrow peninsula, between the Cooper and the Ashley Rivers. Charleston Harbor, supplied by these and some smaller streams, lies between Mt. Pleasant and Sullivan's Island on the northeast, and James and Morris Islands on the southwest. One cannot but be struck with the resemblance, so great as to be almost symmetrical, between the two sides of the harbor. Mt. Pleasant and James Island are quite high land,—high at least for the coast of South Carolina,—and are separated from the mainland, the one by the Wando River, the other by Wappoo Creek; while Sullivan's Island, where stand Fort Moultrie and other Rebel batteries, corresponds almost precisely to Morris Island, both being low and sandy, and being, as it were, bent inland from the sea, with sharp points looking toward the city, their convex shores forming a rounded entrance to the harbor. Extending southward from Morris Island, and separated from it by Lighthouse Inlet, is Folly Island; and in exact correspondence to the latter, north of Sullivan's Island, and separated from it by Breach Inlet, is a similar sand-ridge called Long Island. But now occurs a difference; for while between Long and Sullivan's Islands and Christ's Church Parish is an immense salt marsh intersected by creeks, but presenting an unbroken surface, in the midst of the corresponding marsh between Morris and Folly Islands and James Island is a group of low wooded islands, the largest of which lies opposite the upper or north end of Folly Island. To this no name is given on the maps, nor is it even distinguished from the marsh. It is, however, completely surrounded by water; and, though this is in the form of creeks neither wide nor deep, yet the peculiar softness of the mud, and the absence of any landing-place except upon the side toward Folly Island, render it almost inaccessible.
To this narrow strip of land, not three miles in length, was given the name of Long Island,—perhaps by our own troops, who knew nothing of an island of the same name north of the harbor; and in case it is found that no other name belongs to it, we may properly avoid a confusion, and christen it Spider Island, in honor of the remarkable insects for whose especial benefit it seems to have been made, and which, with the exception of the mosquitoes, are its sole inhabitants.
As was said, the first spider was found on Folly Island on the 19th of August, 1863: it was also the last there seen. During the summer of 1864, many were found on Long Island (so called); and when, in the spring of 1865, our regiment was encamped on James Island near Wappoo Creek, it was toward Long Island that all my attention, so far as concerned spiders, was directed.
But first, as a bit of collateral history, and to show how easily and how far one may go astray when one of the links in the chain of argument is only an inference, let me relate that, while riding over James Island, I observed upon trees and bushes numbers of small brown bags, from half an inch to an inch and a half in diameter, pear-shaped, and suspended by strong silken cords. The bags themselves were made of a finer silk so closely woven as to resemble brown paper, and, when opened, were found to contain a mass of loose silk filled with young spiders to the number of five hundred or more. In certain localities, especially in a swampy field just outside the first line of Rebel works, they were quite abundant. I had soon collected about four hundred of them, which, by a moderate estimate, contained two hundred thousand little spiders,—quite enough, I thought, with which to commence operations. But one hot day in June I placed them all on a tray in the sun. I was called away, and on my return found my one fifth of a million young spiders dead,—baked to death.
Prior to this catastrophe, however, I had become convinced that these were not the spiders I sought. Indeed, my only reasons for thinking they might be were, first, the abundance of these cocoons in a locality so near Long Island; and, second, my own great desire that they should prove the spiders I wanted. The young spiders, it is true, did not at all resemble their supposed progenitors, as to either shape, or color, or markings; yet all of these evidently changed during growth, and would not of themselves disprove the relationship.
One day in April, however, a cocoon was found in a tree on James Island, of a very different appearance from the others. It was of loose texture, and, instead of being pear-shaped, was hemispherical in form, and attached by its flat surface to the lower side of a leaf. This also contained young spiders, a little larger and a little brighter in color than the others, but really bearing no resemblance to the full-grown spiders of Long Island. This single cocoon formed the entering wedge of doubt, and soon it was clear that the only means of proof lay on Long Island itself.
But how was this to be reached? Easily enough while we were upon Folly Island and could row through the creeks to a wharf on the east side of Long Island. But now the case was altered; for between James and Long Islands was the immense marsh already mentioned, intersected by creeks, and composed of mud practically without bottom, and ranging from eighteen to twenty-three feet in depth by actual measurement. Around or over or through this marsh it was necessary to go, in order to reach Long Island, the home of the spiders.
I could easily occupy the rest of my allotted space in recounting my various attempts to reach this El Dorado, which my fancy, excited by every delay, stocked with innumerable cocoons of the kind already found so abundantly on James Island. These I expected would furnish thousands of spiders, the care of which, with the reeling of their silk, would give employment to all the freed people in South Carolina,—for even then the poor creatures were finding their way to the coast. And perhaps, I thought, some day, the Sea-Island silk may be as famous as the choice Sea-Island cotton. This hope I still cherish, together with the belief that, under certain conditions, the spiders may also be reared at the North.
After riding miles and miles in all directions in search of the readiest point of attack; after having once engaged a row-boat to go around through Stono River and meet me at the nearest point of land,—on which occasion I dismounted to give my horse a better chance of getting over a bad place in the road, and the ungrateful beast left me in the lurch and went home much faster than he came, while I, being now half-way, walked on through the marsh, and had the pleasure of sitting on a log in a pouring rain for an hour, with Long Island just on the other side of a creek over which no boat came to carry me,—after this and other disappointments, I at last made sure by going in the boat myself, and so finally reached the island. But now, to my discomfiture, after a most careful search, I saw only two or three cocoons of the kind I looked for, while the others, of loose texture, were quite abundant, and doubtless would have been found in still greater numbers but for their always being under leaves, and often at a considerable height. It was probable now that these latter cocoons contained the spiders, and that the former were a different species.
The regiment now removed to the interior of the State, and while there occurred the coup de soleil above mentioned. We remained at Orangeburg until the middle of August, and then, being stationed at Mt. Pleasant, I again made raids for spiders. Upon James Island, in the localities where during the spring the cocoons were abundant, I found many large geometrical spiders, all of one kind, but not of the kind I sought. They were bad-tempered, and their legs were so short and strong that it was not easy to handle them, while their silk was of a light, and not brilliant, yellow.
My first attempt upon Long Island was made by leaving Charleston in a boat, which, after touching at Sumter, landed me at Fort Johnson. Here I was joined by a sergeant and corporal of the Fifty-fourth Massachusetts, and we walked across to a little settlement of freed people not far from Secessionville, where a boat and crew were engaged. It would be tedious to relate how, after sticking on invisible oyster-beds and mud-flats, and losing our way among the creeks, at two o'clock we found ourselves about one hundred yards from the north end of the island; and how, since it was too late to try to reach the wharf on the east side, even had we been sure of the way, the two Fifty-fourth boys and myself got out of the boat and essayed to cross upon the marsh. Such a marsh! We have marshes at the North, but they are as dry land in comparison. I had seen them at the South, had stepped upon and into them, but never one like this. It was clear mud, as soft as mud could be and not run like the water that covered it at high tide. Even the tall rushes wore an unsteady look; and the few oysters upon its surface evidently required all their balancing powers to lie upon their flat sides and avoid sinking edgewise into the oozy depths. In we sank, over ankles, at the first step, and deeper and deeper till we took a second; for our only safety lay in pushing down the rushes with the inside of one foot and treading upon them, till the other could be withdrawn from its yielding bed, and a spot selected for the next step forward. I say selected, for even this mud was more firm than a hole in it filled with water and treacherously concealed by a few rushes. A misstep into one of these pitfalls brought me to my knees, and well-nigh compelled me to call for help; but a sudden and determined spring, and a friendly bunch of rushes beyond, spared me that mortification. When two thirds of the way across, and while thinking we should soon reach dry land, we came upon the edge of a creek, not wide, it is true, but with soft, slimy, sloping sides, (for banks they could not properly be called,) and no one knew how many feet of mud beneath its sluggish stream. Under ordinary circumstances I might have sounded a retreat; but, remembering that there was twice as much mud behind as before us, and feeling ourselves sinking slowly but surely in our tracks, we slid down the sides into the water. This received our bodies to the waist, the mud our legs to the knees; but we struggled through, and, after another terrible thirty yards of mud, reached Long Island. Leaving my faithful companions to rest, I struck off down the east side of the island, and soon found spiders in plenty. Stopping at the wharf, and returning upon the west side, I counted one hundred spiders in less than an hour. This was only a voyage of discovery, but I could not resist the temptation to capture one big fellow and put it in my hat, which, with the edges brought together, I was forced to carry in my teeth, for one hand was required to break down the webs stretched across my path, and the other to do battle in vain with the thousands of mosquitoes, of huge size and bloody intent, besetting me on every side. What with the extreme heat and my previous fatigue, and the dread lest my captive should escape and revenge herself upon my face while I was avoiding the nets of her friends, and the relentless attacks of their smaller but more venomous associates, it was the most uncomfortable walk imaginable. To complete my misery, the path led me out upon the marsh where I could see nothing of the boat or my companions, and whence, to reach them, I had to walk across the head of the island. Excepting the dreaded recrossing of the mud, I hardly remember how we made our way back; but by one means and another I finally reached Charleston at nine o'clock, about as disreputable-looking a medical man as ever was seen.
However, all this was soon forgotten, and, being now assured of the presence of the spiders in their former haunts, on the 30th of August, 1865, I organized a new expedition, which was to proceed entirely by water, and which consisted of a sail-boat and crew of picked volunteers. Leaving Mt. Pleasant in the morning, we crossed the harbor, and were soon lost in the meanderings of the creeks behind Morris Island. Lost is appropriate, for, once in these creeks, you know nothing, you see and hear nothing, and, if you change your course, must do so by mere guess. But the most annoying thing is, after an apparent advance of a quarter of a mile, to find yourself not twenty yards from your starting-point, so tortuous are the windings of the creeks.
By dint of hard rowing (in the wrong direction, as we soon found), then by walking across Morris Island to Light-House Inlet, and still harder rowing from there to the wharf of Long Island, we succeeded in securing sixty spiders; but now arose a furious storm of wind and rain, which not only compelled our retreat, but drenched us to the skin, blew us back faster than we could row, and threatened to overturn our boat if we hoisted the sail; so slow was our progress, that it was eleven o'clock at night before we reached Mt. Pleasant. Thus ended my last and only successful raid upon Long Island.
It may seem that I have dwelt longer than was necessary upon the circumstances attending the discovery of this spider and its silk. If so, it is not merely because at that time both were new to myself and all to whom I showed them, and everything concerning them was likely to be impressed upon my mind, but also because I then hoped that the idea of obtaining silk directly from a living insect might be found of practical importance, as I still hope it may. The incidents illustrate, too, the nature of the obstacles daily encountered and overcome by our troops; for no one who has never seen or stepped into a Sea-Island marsh can realize how difficult it was for our forces to obtain a foothold in the vicinity of Charleston. This was appreciated by the old freedman whom we left in the boat while crossing the mud. "No wonder," he said, "the Yankees whipped the Rebels, if they will do such things for to catch spiders."
The sixty spiders so obtained were kept for several weeks in the little boxes in which they had been deposited when caught. Every day each box was opened, the occupant examined, and its condition, if altered, noted on the cover. They generally spun a few irregular lines on which to hang, and so remained quiet except when the boxes were opened: then, of course, they tried to escape. Half a dozen of the larger ones were placed on the window-seats and in corners of the room, where they speedily constructed webs. By preference these were stretched across the windows, illustrating one of the three principal instincts of this spider, which are, first, to seek the light; second, to ascend; and third, to take a position with the head downward.
It was now a question how they were to be fed; not so much while there, where flies were abundant, but after their arrival at the North. So, remembering that the young ones had seemed to relish blood, I took the tender liver of a chicken, cut it into little pieces, and dipped them in water, not, I am sorry to say, with any view to supply them with that fluid for the want of which they afterward perished, but in order that the bits of liver should be more easily pulled from the pins by the spiders. To my delight they greedily accepted the new food, and now I felt assured of keeping them during the winter.
Deferring, however, a more particular account of what was observed at Mt. Pleasant, until their habits and mode of life are taken up in order, it should be understood that, during our short stay, my attention was chiefly directed to getting from the spiders as much silk as possible; for it was evident that practical men would not credit the usefulness of spiders' silk until an appreciable quantity could be shown to them. The first trial of the machine with a live spider proved it an utter failure; for though quite ingenious and complicated, it had been devised with reference only to dead spiders. In regard to the arrangement (wherein lay its chief, if not sole, peculiarity) by which a thin slip of brass was sprung against a rubber band by the latter's elasticity, with a view to secure the spider's legs between them, it was found that, as the spider was alive, and, literally, kicking, and two of its legs were smaller than the rest, these were at once extricated, and the others soon followed; while, if the spring was made forcible enough to hold the smaller legs, the larger were in danger of being crushed, and the spider, fearing this, often disjointed them, according to the convenient, though loose habit of most Arachnida, crabs, and other articulates. It was also proposed to secure several spiders in the above manner upon the periphery of a wheel, the revolution of which would give a twist to their conjoined threads, carried through a common eyelet upon the spindle; but this can be accomplished without the inconvenience of whirling the spiders out of sight, by modifications of the apparatus which has always been used for twisting ordinary silk. It will probably be inferred from the above, that, in securing the spider, two points are to be considered; first, to prevent its escape, and second, so to confine the legs that it cannot reach with their tips either the silk or the spinners. Now the machine accomplished this by putting all the legs together in a vice, as it were, entailing upon the captive much discomfort and perhaps the loss of some of its legs, which, though eight in number, are each appropriated to a special use by their possessor.
So, abandoning the machine, I fell back upon a simple reel, and a modification of my little contrivance of the previous year; which was, to grasp the spider by all the legs, holding them behind her back, and to let her body down into a deep notch or slot cut in a thin card, the edges of which reached the constriction between the two regions of the body, the cephalothorax and abdomen; so that, when a second piece of card was let down upon it, the cephalothorax, with the legs of the spider, was upon one side of a partition, while on the other was the abdomen, bearing upon its posterior extremity the spinning organs. The head and horns of a cow to be milked are secured in a similar manner. By placing in a row, or one behind another, several spiders thus secured, a compound thread was simultaneously obtained from them, and wound upon a spindle of hard rubber.
By this means were produced several very handsome bands of bright yellow silk; but the time was so short, and the means of constructing and improving my apparatus so deficient, that I could procure no more than these few specimens, which were very beautiful, and shone in the sun like polished and almost translucent gold; but which, being wound upon a cylinder only an inch in diameter, and from several spiders at different times, could not be unwound, and so made of any further use.
I tried now to ascertain how much silk could be obtained from a single spider at once. It will be remembered that the first specimen, wound on Folly Island, was one hundred and fifty yards in length, and weighed one third of a grain. I now exhausted the supply of a spider for three days, using the same spindle, one inch in diameter, and turning this at the rate of one hundred and sixty times per minute. On the first day I reeled for twenty minutes, which gave two hundred and sixty-six and two thirds yards; on the third day, the second being Sunday, for twenty-five minutes, giving three hundred and thirty-three and one third yards; and on the fourth day, for eighteen minutes, giving two hundred and thirty-three and one third yards,—amounting in all to eight hundred and thirty-three and one third yards in three or four days. This was all that could be got, and the spider herself seemed unable to evolve any more; but on killing her and opening her abdomen, plenty of the gum was found in the little silk bags into which it is secreted. As this has always been the case, I have concluded that the evolution of the silk is almost entirely a mechanical process, which is but little controlled by the spinners themselves, and that the gum requires some degree of preparation after it is secreted before it is fit for use as silk; for it must be remembered that with the spider, as with the silk-worm, the silk is formed and contained in little bags or glands in the abdomen, not as threads, but as a very viscid gum. This passes in little tubes or ducts to the spinners, through minute openings, in which it is drawn out into filaments, uniting and drying instantly in the air, and so forming the single fibre from each spinner.
The silk obtained the first day was of a deep yellow; to my great astonishment, the second reeling from the same spider gave silk of a brilliant silver-white color; while on the third occasion, as if by magic, the color had changed again, and I got only yellow silk. The hypothesis of individual peculiarity, adopted the previous year to explain why some spiders gave yellow, and others white silk, was now untenable; and, remembering that, beside these two positive colors there was also (and indeed more commonly) a light yellow, as if a combination of the other two, I saw that the real solution of the mystery must lie in the spinners themselves. Examining carefully the thread as it came from the body, it was seen to be composed of two distinct portions, differing materially in their size, their color, their elasticity, and their relative position; for one of them was white and inelastic, crinkling and flying up when relaxed, and seemed to proceed from the posterior of the two principal pairs of spinners, while the other was larger, yellow, so elastic that when relaxed it kept its direction, and seemed to come from the anterior pair of spinners, and so, in the inverted position of the spider, was above the other. By putting a spider under the influence of chloroform, and then carrying the first thread under a pin stuck in a cork to one part of a spindle, and the second or yellow line over another pin to a different part of the spindle, I reeled off from the same spider, at the same time, two distinct bands of silk, of which one was a deep golden-yellow, the other a bright silver-white; while, if both threads ran together, there was formed a band of light yellow from the union of the two. Thinking such a difference must subserve some use in the economy of the insect, I made a more careful examination of its webs. At first sight these resembled those of most geometrical spiders, in being broad, rounded, nearly vertical nets; but they were unusually large, and in their native woods often stretched between trees and across the paths, so as to be two, three, and even more, feet in diameter, and in my room at Mt. Pleasant hung like curtains before the windows. They were of a bright yellow color and very viscid; but now I noticed that neither the color nor the viscidity pertained to the entire net, for although the concentric circles constituting the principal part of the web were yellow, and very elastic, and studded with little beads of gum, (Fig 3,) yet the diverging lines or radii of the wheel-shaped structure, with all the guys and stays by which it was suspended and braced, were dry and inelastic, and of a white or lighter yellow color.
Fig. 3. Silk threads, viscid and dry. Now, however, a new mystery presented itself. We will admit that the spider had the power, not only to vary the size of her lines according to the number of spinners, or of the minute holes in each spinner, which were applied to the surface whence the line was to proceed, but also to make use of either golden or silver silk at will. But how was it that this yellow silk—which was quite dry and firm, though elastic, as reeled from the spider, or as spun by her in the formation of her cocoons—was nevertheless, when used for the concentric circles of the web, so viscid as to follow the point of a pin, stretching in so doing many times its length? A satisfactory explanation of this has never yet been offered, nor can be until the minute anatomy of the spinning organs is better understood, and the evolution of the silk more carefully observed at every stage, and under all conditions. I will merely state very briefly the few facts already established, with some of the possible explanations.
The spinning mammulæ are placed in pairs at the lower part of the abdomen, near its hinder end, and number four, six, or eight in different species. They are little conical or cylindrical papillæ, closely resembling the pro-legs of caterpillars, and are composed of two or three joints, the terminal one of which is pierced with a greater or less number of minute holes, the sides of these, in some, if not all, cases, being prolonged into tubes. Through these holes or tubes issue the fine filaments, which, uniting as they dry in the air, constitute the line from each spinner.
Fig. 4. Spinners. Now the Nephila plumipes possesses at least three pairs of spinners. Of these, two are much larger than the third, which indeed does not appear till they are separated. From the posterior of the two largest pairs seems to proceed the white, and from the anterior the yellow silk, while from the small intermediate pair seem to proceed very fine filaments of a pale-blue color, the use of which is to envelop the prey after it has been seized and killed, being drawn out by the bristles near the tips of the spider's hinder legs. Beside these six papillæ there is, just in front of the anterior pair, a single small papilla on the middle line, the nature and use of which I have not ascertained, though I feel quite sure that no silk comes from it. The large median papilla, just behind the posterior pair, surrounds the termination of the intestines, and through it the excrement is voided, the insect for this purpose turning back the abdomen as she hangs head downward, so that neither the web nor the spinners shall be contaminated. Now it has recently been ascertained that the minute globules with which the circles are studded, and the number of which on a web of average size is estimated at one hundred thousand, do not exist in that form when the viscid lines are first spun by the spider, but as a uniform coating of gum upon a thread; this gum, of itself and according to physical laws, soon exhibits little undulations, and then separates into the globules which have long been observed and supposed to be formed by the spider. The fact of spiders selecting the night for the construction of their webs, the difficulty of making any close observations upon them while so engaged without disturbing them, and the near approximation of the two larger pairs of spinners while the viscid line is slowly drawn out by the hind leg, have hitherto prevented my determining its exact source and manner of formation. If it comes from the anterior pair only, then one and the same organ has the power of evolving a central axis and covering it with viscid gum; and it seems less improbable that the axis is white and formed by the posterior pair, the yellow gum being spread upon it by the anterior pair, which also would then have the power to evolve this same gum at other times as an equally dry, though more elastic thread. But in either case we have only three pairs of spinners and four kinds of silk, the pale-blue fasciculi the dry white, the dry yellow, and the viscid and very elastic silk which is employed only in the circles of the web, and which often does not become yellow till after exposure to the light. Apparently the surest method of investigation will be carefully to destroy one pair of spinners at a time without injuring the others, and then note the effect upon the spinning.
Let us go back now to the sixty spiders left at Mt. Pleasant. A few of these died on the way North, but the majority reached Boston in safety about the 20th of September, 1865; for some time I had observed that they all were becoming more or less emaciated, and relished their food less than at first. Occasionally one died from no apparent cause. The mortality increasing toward the end of the month, and all of them losing both flesh and vigor, I was persuaded to try them with water,—a thing I had thus far declined to do, never having heard of a spider's drinking water, and knowing that our common house species can hardly get it at all. The result was most gratifying: a drop of water upon the tip of a camel's-hair pencil, not only was not avoided, but greedily seized and slowly swallowed, being held between the jaws and the palpi. All of the spiders took it, and some even five or six drops in succession. You will exclaim, "Poor things! what tortures they must have suffered!" I admit that it could not have been pleasant for them to go so long without that which they crave every day, but I cannot believe that creatures whose legs drop off on very slight provocation, and which never show any sign whatever of real pain, suffered very acute pangs even when subjected to what occasions such distress to ourselves.
The few survivors straightway improved in health and spirits; but being now convinced that a moist atmosphere was almost as needful as water to drink, I turned them loose in the north wing of the hot-house in Dr. Gray's Botanical Garden at Cambridge. They all mysteriously disappeared, excepting one, which made a nice web at one end just under the ridge-pole, and for several weeks lived and grew fat upon the flies; but a thorough fumigation of the house with tobacco so shocked her not yet civilized organization that she died.
Her untimely death, however, afforded opportunity for a closer examination of the web itself. The first one she had made was not vertical; and, following the prevalent ideas as to the precise construction of the spider's web, I had felt somewhat ashamed of my pet, but supposed the next she made would be an improvement. But no, the rebellious insect constantly made them all (for, it should have been said before, this spider seldom uses the same web more than forty-eight hours) after the same manner, and finally I laid it to a depraved idiocrasy, incident to captivity and poor health. But now another and most unexpected feature developed itself; for, on attempting to remove the last web by placing against it a large wire ring, and cutting the guy-lines, I found that this most degenerate spider had not only failed to make her house perpendicular, but had so far departed from the traditions of our ancestors as to have the centre thereof decidedly eccentric, and four times as near the upper as the lower border of the web, so that its upper portion was only a confused array of irregular lines, which it was impossible to secure to the frame. For any accurate observation my web was of no value. But perhaps this was best; for had I then learned what I have since, that our spider utterly ignores every precedent, not only in the position and shape of her web, but also in its minute arrangement, I might have been so affected by her evident bad character and radical proclivities, as to have feared paying her any further attentions,—much more, presenting her to the world.
But in order to understand how these further discoveries were made, we must again go back to the original sixty spiders in my room at Mt. Pleasant, South Carolina.
At the time of their capture, I had observed upon a few of the webs little brown spiders, which I then imagined might be the half-grown young. Six of these were found among the sixty larger spiders, and a moment's examination of their palpi or feelers (Fig. 5) showed that they were males, though even then I could not believe they had reached their maturity; for their bodies were only about one fourth of an inch in length, and weighed only one thirty-second part of a grain, while the females were from an inch to an inch and a quarter in length, and weighed from three to four grains. It was as absurd as if a man weighing one hundred and fifty pounds were joined to a bigger half of eighteen thousand pounds' weight, and I was not fully convinced that these small spiders were really the males of the Nephila plumipes till I had witnessed the impregnation of the eggs of the females by them.
Fig. 5. Palpi, or Feelers. One morning, in the cell of a large female, I found a cocoon of beautiful yellow silk containing a rounded mass of eggs. Soon the same occurred with other females, and there were fifteen cocoons, which would give about seven thousand spiders. Early in October, just one month after they were laid, the eggs of the first cocoon were broken and disclosed little spiders with rounded yellow bodies and short legs, looking about as little like their parents as could be imagined. The eggs in the other cocoons followed in their order, and now each contained four or five hundred little spiders closely packed.
For some time they seemed to eat nothing at all; but within a few days all had shed their skins, and now the abdomen was smaller, while the cephalothorax and legs were larger and darker; but they showed no desire to leave their cocoons. Still they grew perceptibly; and coincident with this was a less pleasing fact: their numbers were decreasing in the same proportion, and occasionally one was seen eating another. It was some time before I could reconcile the good temper and quiet behavior of the parents with this instinctive and habitual fratricide on the part of their children. But look at it in this way: here were several hundred active little creatures in a space just large enough to contain them; presently they were hungry, and as no two could be of exactly the same size, the smaller and weaker naturally fell a prey to their larger brethren, or rather sisters, for either very few males are hatched, or else they are particularly good eating, and a very small proportion survive the perils of infancy. It is evidently an established and well-understood thing among them: all seem to be aware of their destiny, to eat or be eaten. What else can they do? Human beings would do the same under the same circumstances; and I have never seen the least sign of personal spite or malignity in the spider. There is no pursuit, for there is no escape; and we can only conclude that, as the new-born fish's first nourishment is the contents of the yolk-sac, partly outside, though still a portion of its body, so the first food of the young spiders is, if not themselves, the next best thing,—each other. Thus it is provided that the smaller and less vigorous shall furnish food for the larger until the latter are strong enough to venture forth in search of other means of support.
In consequence of this mutual destruction, aided materially by the depredations of birds and of other insects, and by exposure to the weather, only about one per cent of those hatched reach maturity. If properly protected, however, a far larger proportion may be saved; and as their multiplication is so rapid, no fear need be entertained of a limit to the supply.
By keeping these little spiders in glass jars, inverted, and with a wet sponge at the bottom, they were easily watched and cared for. At first only about one twentieth of an inch long and nearly as wide, they increased in length as they grew, but for many weeks lived in common on an irregular web, feeding together on the crushed flies or bugs thrown to them. But when one fourth of an inch in length, they showed a disposition to separate, and to spin each for herself a regular web, out of which all intruders were kept. And now it was found that all these webs were inclined at nearly the same angle, and were never exactly vertical; that, like the spider in the first web she made in the Botanical Garden, the insect took a position much nearer the upper than the lower border; and also that, instead of a web of perfect circles laid upon regular radii, as used to be described and is still figured in our books, or even one of a spiral line, as is now more correctly described of ordinary geometrical spiders (Fig. 6), these never made a circle, nor even a spiral, but a series of concentric loops or arcs of circles, the lines turning back upon themselves before reaching a point over the spider, and leaving the larger portion of the web below her; and more than this, that the lines, though quite regular, were by no means perfectly so, as may be seen in Fig. 7, copied from a photograph.
Fig. 6. Web of common Garden Spider.
Fig. 8. Section of Web.As usual, the radii, or spokes, of the wheel-shaped structure are first made; then the spider begins a little way from the centre, and, passing from one radius to another, spins a series of loops at considerable distances from each other till she reaches the circumference. These first loops, like the radii, are of white, dry, and inelastic silk, and may be recognized by the little notches at their junction with the radii. The notches are made by the spider's drawing her body a little inward toward the centre of the web at the time of attaching them to the radii, and so they always point in the direction in which the spider is moving at that time, and in opposite directions on any two successive lines (Fig. 8). Having reached what is to be the border of her web, and thus constructed a firm framework or scaffolding, she begins to retrace her steps, moving more slowly and spinning now in the intervals of the dry loops two or three similar loops, but much nearer together and made of the elastic and viscid silk, till she has again reached her starting-point near the middle of the web, where, on its under side, she takes a position, head downward, hanging by her claws, and thus keeping her body from direct contact with the web.
Fig. 7. Web of Nephila plumipes.
Here she will remain quiet for hours as if asleep; but no sooner does a fly or other insect strike the web, than she darts in the direction whence the vibrations proceed, and usually seizes her prey; but, strangely enough, if the insect have ceased its struggles before she reaches it, she stops, and if she cannot renew them by shaking the web with her claws, will slowly and disconsolately return to the centre of the web, there to await fresh vibrations. These and many other facts, even more conclusive, have satisfied me that, although this spider has eight eyes (Fig. 9), it is as blind as a man with his eyelids shut, and can only distinguish light from darkness, nothing more. This seems to be the case with other geometrical species, but not at all with the field and hunting spiders, some of which will boldly turn upon you and look right in your eyes; they alone, of all insects, seeming to recognize the face of man as different from his body.
Fig. 9. Face and Jaws, magnified (eyes dimly seen).The hearing and touch of this spider are very acute. The latter is exercised by the palpi and the tips of the legs, especially the first pair, but no ear has yet been discovered; neither is anything known of the organs of taste and smell, or even whether the insect possesses these senses at all.
I ought before this to have anticipated and answered a question which nine out of ten, perhaps, of my readers have already asked themselves, "Do not spiders bite? and is not their bite poisonous, nay, at times, deadly even to man?" The answer is, in brief, Yes, spiders do bite, probably all of them, if provoked and so confined that they cannot escape; though only a few tropical species can be said to seek of their own accord an opportunity for attacking man, or any creature larger than the insects that form their natural prey. Even the Nephila plumipes, which, it has been intimated, is "Christian in its disposition, and well-behaved beyond most of its kind," will readily bite, if it is held in the fingers and anything is put to its jaws. But that is nothing. So would you, most gentle reader, if a great giant pinched you between his thumb and finger, and held your hands and feet and head; and if, too, like our spider, you could not see enough to distinguish friends from foes. Spiders, then, will bite. But to the second part of the inquiry our answer must be less positive. They have a very bad name; but much of this is due to their grim and forbidding aspect, and their bloody trade of trapping and eating poor little insects. It is to be remembered that there are very few, if any, medical reports of injuries from the bites of spiders, and that the accounts of such cases occurring in the newspapers consist in great measure of inference, and either make no mention of the offender at all, or merely speak of a little black or gray spider being found in the vicinity. A number of experiments have been made in England to ascertain the effect of the bite of the larger geometrical spiders upon the experimenter himself, upon other spiders, and upon common insects; and the conclusion was, that it produces no greater effect than the prick of a pin, or any other injury of equal extent and severity; while the speedy death of its victim is ascribed to the spider's sucking its juices, rather than to any poison instilled into the wound. But these experiments, though somewhat reassuring, are not conclusive; for they were tried only on one person, and people vary much in their susceptibility to poison of all kinds; moreover, the spiders employed were of the geometrical kinds, which have never been so much feared as the larger field and hunting spiders. Indeed, it may be found that among spiders there is as great a difference in respect to venom as among serpents, and that those which depend upon their jaws for taking and holding their prey, such as the field and hunting spiders, are poisonous, while the web-builders which ensnare their victims are not so. In regard to our spiders, I have caused a large one to bite, so as to draw blood, a kitten three days old, and the kitten has not appeared to suffer in the least on that account.
They are very quiet insects, and never appear disturbed at what goes on about them; neither do they run away and hide in holes and corners, like our common spiders; but if their webs are injured, or they are startled by a noise, they will shake themselves from side to side in their webs, so as to be wholly invisible. Their natural food is insects of all kinds; but they soon learn to eat soft flesh, such as the liver of chickens, for which, as well as for water, they will sometimes stretch themselves and turn in their webs so as to take it from the point of a pin or camel's-hair pencil. Besides water to drink, they require an atmosphere saturated with moisture, like that of their native island, the relative humidity being about seventy on the Hygrodeik scale. If stroked upon the back, they often raise their bodies as a cat does, and sometimes put back a leg to push away your finger. They may be allowed to run over one's person with perfect safety, but, if suddenly seized, will hold on with tooth as well as nail.
They are quite economical, and every few days, when the web has become too dry and dusty for use, will gather it up in a mass, which they stuff into their jaws and masticate for hours, swallowing the gum, but throwing out the rest, with the little particles of dust, in the form of a hard black pellet,—an instance rare, if not indeed unique, of an animal eating a substance already excreted from its body.
Here I must close, though much against my will. It would please me to describe, as it has almost fascinated me to observe, the doings of my spiders, as they grew older and made their webs in the Wardian cases to which they were removed when too many and too large for the jars; how the young are gregarious, and move from place to place in a close column, protected on all sides by skirmishers, which continually report to the main body; how some of these young, whose parents were caught on Long Island, South Carolina, a year ago, and which were hatched from the egg in October last, have grown up during a Northern winter, have themselves become parents and laid eggs; how they periodically cast off their skins, even to that of the eyes, the jaws, and the breathing tubes, and how, from too great impatience, sad accidents sometimes befall them on these occasions; how, also, I have reeled silk from several of these spiders, and made a thread which has been woven in a power-loom as a woof or filling upon a warp of common black silk, so as to make a bit of ribbon two inches wide, thereby proving that it is real silk and can be treated as such.
Much, too, could be said of the only other attempts to utilize spiders' silk, a knowledge of which would have materially aided me. In France, one hundred and fifty years ago, M. Bon made gloves and stockings of silk got by carding spiders' cocoons, and seventy years later, as I have but recently ascertained, Termeyer, a Spaniard, not only used the cocoons, but also, by an observation similar to my own, was led to reel the silk from the living insect. He, however, had poorer spiders or too little perseverance, or friends and a government influenced by a most short-sighted economy and prudence, else the highly interesting and instructive account of his experiments would have been familiar to some one in this country, and would not have waited these many years to be found by accident last spring in an obscure corner of the Astor Library.
I will add, finally, that I believe some other geometrical spiders, especially of the genus Nephila, may be found as docile, and as productive of beautiful silk, as the species I have described. At any rate, you cannot find a more interesting inmate of your Wardian case than some large geometrical spider.