Webbing (anatomy)

“ For instance, it is possible that the feet of our water-dogs, and of the American dogs which have to travel much over the snow, may have become partially webbed from the stimulus of widely extending their toes; but it is far more probable that the webbing, like the membrane between the toes of certain pigeons, spontaneously appeared and was afterwards increased by the best swimmers and the best snow-travellers being preserved during many generations. ”

“ Webbing between fingers one and two is basal in all species. Webbing between fingers two, three, and four is most extensive in taurinus, in which the three fingers are about one-half webbed (Fig. 5) . Osteocephalus buckleyi, pearsoni, and verrucigerus have reduced webbing between fingers two and three, and leprieurii has reduced webbing between fingers two, three, and four. All members of the genus have well-developed subconical subarticular tubercles on the fingers and toes; there is a tendency for the distal tubercle on the fourth finger to be weakly bifid. ”

“ Those which radiate from the centre to the circumference are strong and smooth, while those which unite them are much slighter, and are covered with tiny globules set at regular intervals. When the web is newly spun, these globules are found to be nearly as tenacious as birdlime, and it is by these means that an insect which falls into the web is arrested,{101} and cannot extricate itself until the spider can seize it. After awhile the globules become dry, refuse to perform their office, and then the spider has to construct another web. ”

“ Not the ordinary single web which we all know, but a broad band which represents the many hundreds of strands usually combined in the single thread, but now permitted to issue singly from the spinnerets. White speaks of the spider "shooting out" the web, and such is the apparent feat, but doubtless the breeze assists in the operation. It is certainly taking good care of this floating banner from the loom of this little spinner upon our finger-tip. Longer and longer it grows. ”

“ Rightly considered, a Spider's web is a most curious as well as a most beautiful thing. When we were children, the majority of us supposed that the Spider's web was pulled out of its mouth, and that the little insect had a large reel of the stuff in his stomach, and that he could almost instantly add feet, yards, or rods to the roll. ”

“ Hence, from each spinner proceeds a compound thread; and these four threads, at the distance of about one-tenth of an inch from the apex of the spinner, again unite, and form the thread we are accustomed to see, which the spider uses in forming its web. Thus, a spider’s web, even spun by the smallest species, and when so fine that it is almost imperceptible to our senses, is not, as we suppose, a straight line, but a rope, composed of at least 400 yarns. ”

“ If anyone destroys the web, she begins spinning again at the rising or setting of the sun, for it is at this time that her prey usually falls into the web. The female both makes the web and pursues the prey. The male only enjoys it with her.
6. There are two kinds of graceful spiders that spin a thick web, one large and one small. The one with long legs keeps watch suspended above its web, that the creatures which fall into the web may not be frightened when taken, and then it falls upon them from above, for its size prevents [Pg 260] it from being easily concealed. ”

“ Insects flying through the web strike the sticky threads and, trying to free themselves, fall against others. The spider at the center of the web feels the movements of the insect and goes toward it by the nearest ray and, drawing out silk from the spinnerets, throws it around the insect until it is tied fast. Adult male Epeiridæ are seldom seen in webs of their own, but some of them do occasionally make webs. ”

“ If, however, the molecules could turn with perfect freedom, it is clear that the smallest magnetizing force would be sufficient to develop the highest possible degree of magnetization, which is of course not the case. Weber therefore supposed each molecule to be acted on by a force tending to preserve it in its original direction, the position actually assumed by the axis being in the direction of the resultant of this hypothetical force and the applied magnetizing force. ”

“ Weber's theory differs from this in assuming that the molecules of the iron are always magnets, even before the application of the magnetizing force, but that in ordinary iron the magnetic axes of the molecules are turned indifferently in every direction, so that the iron as a whole exhibits no magnetic properties. ”

“ The spider walks on the nearest sound thread, and gathers in with her front-feet as much old web as she can tear off, and rolls it up with her palpi and mandibles into a ball, and, when it is tight enough not to stick to the web, drops it. As she walks along, gathering up the old web in front, she at the same time spins a new thread behind, and, when she gets to a suitable place, makes it fast as one of the rays of the new web. The common story has it, that the spider eats the old web. ”

“ The size of the web is usually proportioned to that of the spider; but Epeira displicata, which is quarter of an inch long, makes a web only two or three inches in diameter, on the ends of branches of bushes, where it is shaken about, and sometimes blown to pieces, by the wind. ”

“ By beginning thus at the outside, the spider is able to cover the whole web with adhesive threads, and, without stepping on it, take her usual place in the centre. She usually is careful enough to spin beforehand a thread from the centre to her nest, and sometimes stays there, with one foot on the thread, so as to feel if any thing is caught in the web. When she feels a shake, she runs down to the centre, feels the rays to see where the insect is, and runs out, and seizes it, or ties it up as described on page 43. We have described the web as consisting of one regular spiral ”

“ 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. ”

“ The position must also offer favourable opposite points for the attachment of the web itself. People have often puzzled their brains, wondering how spiders, without being able to fly, had managed first to stretch their web through the air between two opposite points. But the little creature succeeds in accomplishing this difficult task in the most various and ingenious ways. It either, when the distance is not too great, throws a moist viscid pellet, joined to a thread, which will stick where it touches; or hangs itself by a thread in the air and lets itself be driven by the wind to the spot ”

“ When a magnetic force acts on the iron it tends to turn the axes of the molecules all in one direction, and so to cause the iron, as a whole, to become a magnet.
If the axes of all the molecules were set parallel to each other, the iron would exhibit the greatest intensity of magnetization of which it is capable. Hence Weber's theory implies the existence of a limiting intensity of magnetization, and the experimental evidence that such a limit exists is therefore necessary to the theory. ”

“ Her web is like that of the other weaving Spiders. Straight threads run out like spokes of a wheel from a central point. Over these runs a continuous spiral thread, forming chords, or cross-bars, from the center to the circumference. It is magnificently large and magnificently symmetrical.
In the lower part of the web, starting from the center, a thick wide ribbon descends zigzag-wise across the spokes. This is the Spider’s trademark, the way she signs her work of art. Also, the strong silk zigzag gives greater firmness to the web. ”

“ This gregarious habit, in so typical a genus as Epeira, among insects, which are so bloodthirsty and solitary that even the two sexes attack each other, is a very singular fact.
In a lofty valley of the Cordillera, near Mendoza, I found another spider with a singularly-formed web. Strong lines radiated in a vertical plane from a common centre, where the insect had its station; but only two of the rays were connected by a symmetrical mesh-work; so that the net, instead of being, as is generally the case, circular, consisted of a wedge-shaped segment. All the webs were similarly constructed. ”

“ We know in what a strange way the Spider weaves her web and divides the area of the web into a large number of equal parts or sectors, a number which is almost always the same in the work of each species of Spider. The Spider darts here and there when laying her spokes as if she had no plan, and this irresponsible way of working produces a beautiful web like the rose-window in a church, a web which no designer could have drawn better with compasses. ”

“ A fine large web it was when finished, and with this about it that set it off from all the other webs thereabouts, that it seemed to stand straight up in the air, without anything to show what held it. It takes pretty sharp eyes to make out a single strand of a spider-web, even a very little way off. ”

“ I can still see him sitting on the end of the table in my cell, which was fastened with iron clamps to the wall, jerking his long, thin legs, and flourishing his long, thin arms, like a great spider who finds a broken mesh in his web. It was probably a hard task for so learned a spider, into whose web a clumsy blue-bottle had blundered and was floundering about in his awkward way, to extricate him with scientific nicety. And now for the first time I began to find out how far-spreading this web was, and how many flies, besides myself, were entangled in its meshes. ”

“ The main or radial threads which fasten the web possess such a high degree of elasticity, that they tighten themselves between two distant points to which the spider has crawled, without it being necessary for the latter to pull them towards itself. When the little artist has once got a single thread at its disposition, it strengthens this until it is sufficiently strong for it to run backwards and forwards thereupon, and to spin therefrom the web. ”

“ Whatever other variations there may be in the spider's work, as to the size and proportions of the net, and the number of interradial lines, the number of radii is constant. In more than a hundred nets, I have found the number to be four, never more nor less. Now, this seems to offer a confirmation of the common idea that spiders' webs, like bees' cells, are constructed with absolute accuracy, and are models for poor humanity.
Fig. 11.—Net of Nephila plumipes, made in a wire frame, and photographed upon wood reduced. In nature, the free radii, as above described, occupy about 1⁄6of the area ”

“ Now when the dome-shaped web is ready to be filled with air the spider rises to the surface, lifts its abdomen above it, and brings it down with a flop, thus imprisoning an extra large air-bubble which it embraces with its hind-legs by way of holding it more securely, and then, swimming rapidly down by means of its other legs to the web it discharges its load of air beneath the downwardly directed mouth of the dome. ”

“ As soon as the inner spiral is found in the way a part of it is cut out, and by the time the outer spiral is finished the inner is reduced to the small and close portion near the center.... The whole making of the web seems to be done entirely by feeling, and is done as well in the dark as in daylight. When the spider is active and the food supply good, a fresh web is made every day, the old one being torn down and thrown away. ”

“ As a spider makes its web out of its own substance, and becomes bound in it, and cannot go anywhere except along the lines of that web, so we have projected out of our own substance this network called the nerves, and we cannot work except through the channels of those nerves. ”

“ 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. ”

“ The next thing that the spider does is to spin a little silken platform in the middle of her web to sit upon. And as soon as she has done this she begins to spin the spiral thread. Beginning from the center, she goes round and round and round, fastening the thread down every time that it crosses one of the straight cords—the spokes, as it were, of the wheel—until at last the web is finished. ”

“ Q. Who teaches the spider to make its web? A. God. Q. Could any man in the world make a spider's web? A. No, no one could do it.
The teacher may then add thus:—Thus you see, little children, that every living thing has some merit of its own, and can do many things which we cannot do, although God has given us the means to become so much wiser than they; and be sure you are not frightened at them, nor put them to unnecessary pain. Some other day I will tell you what is the shape of the spider's web, and shew you what a number of regular figures the spider's web is composed of. ”