ENTOMOLOGY THE SPIDER. 87 



. . . Spiders, according to the dissections of M. Treviianus, have four principal ves- 

 sels, two larger and two smaller, with a number of miiiute ones at their base. Several small 

 tubes branch toward the reservoirs, for canning to them, no doubt, a snpjjly of the secreted 

 material. . . From these little llasks or bags of gum, situated near the apex of the abdo- 

 men, and not at the mouth as in caterpillars, a tid)e originates, and terminates in the external 

 spiuuerets, which may be seen by the naked eye in the fonn of live little teats suiTounded 

 by a small ciritle, as represented in Fig. 8, I'late IV.; tljis iignre shows the garden spider 

 (Epeira dladema) sus|)ended by a thread proceeding from its spinneret. . . On looking 

 with a strong magnifying glass, at the teat-shaped spinnerets of a spidcir, we pei'ceive them 

 studded with regular rows of minute bristle-like points, about a thousand to each teat, mak- 

 ing in all friini hvo to si.x thousand. These are minute tubes which we may appropriately 

 tenii spiiinendcs, as each is connected with the intennd reservoirs, and emits a thread of in- 

 conceivable fmeness. Fig. 9 represents this wonderfi.il apparattis as it appears in the micro- 

 scope. 



We do not recollect that naturalists have ventured to assign any cause for this very re- 

 markable tnulfi[)licity of the spinneniles of spiders, so diftei-ent from the simple sjjinneret 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 (|uickly. It is well 

 known in our manufactures, particidarly in rope-spinning, that in cords of etjual 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, hiasmuch 

 as it is composed of fluid materials that require to be dried rapidly, and this drying nmst be 

 CTeatly facilitatful by exposing so many to the air separately before their luiioii, which is ef 

 fected at about the tenth of an inch from the spinnerets. In Fig 10, I'late IV. each of the 

 threads showai is represented to contain one hundred minute threads, the whole fonuing only 

 one of the spider's common threads. In the figure the threads are, of course, gi'eady magni- 

 fied, so that, for the small sj)ace represented, the lines are showni as parallel. . . 



Reauunn- relates that he has often counted as many as seventy or eight)- fibres through a 

 microscope, and perceived that there were yet uifinitely more than he could reckon ; so 

 that he believed liimself to lie far within the limit of tiiitli in computing that the tip of eack 

 of the five pa])ilhe funiished 1,000 separate fibres : thus supposing that one slender filament 

 of a spider's web is made up of ,5,000 fibres! 



Leeuwenhoeck, in one of his extraordinary microscopical obsen'ations on a young spider, 

 not bigger than a grain of sand, upon enumerating the threadlets in one of its threads, calcu- 

 lated that it would require /o7/r millions of them to be as thick as a hair of his head ! 



Another important advant^ige derived by the spider from the multiplj(-it)- of its threadlets 

 is, tliat 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 fix a thread, the spinneiides are extended over an area of 

 some diameter, from eveiy hair's breadth of which a strand, as rope-makers tenn it, is ex- 

 tended 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 Ime is 

 attached to any black object, for the threatls, being whitish, are, in otherwise, not so easily 

 perceived. 



Shooting of thk link*. — It has long been considered a curious though difficult investiga- 

 tion, to detemiine in what manner spiders, seeing that they are destitute of wings, ti-ansport 

 themselves from ti-ee to tree, across brooks, and fretpiently through the air itself, without 

 any apparent starting point. On looking into the authors who have ti-eated upon this sub- 

 ject, it is suiprising how little there is to be met with that is new, even in the most recent. 



Here the author gives the theories of various writers, which, we agree with 

 him, seem to be neither reasonable nor satisfactory — some of them proved to be 

 unfounded and impracticable ; and finally he inclines to that of Mr. Blackwall, 

 who says : 



Having procured a small branched twi?, I fixed it upright in an earthen vessel containing 

 water, its base being iiniuersed in the li()ui(l, 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, thcj- directly turned the thorax toward the quarter whence 

 it came, even \vhen 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 liner ones, with a velocity equal, or nearly so, to that witli which 

 the air moved, as was apparent from observations made on the motion of detached linos similarly 

 expo.sed. The spider.s, in the next place, carefully a.sccrtained whether their lines had become 

 firmly attached to any object or not, by pulling at them with the front pair of legs : and il the re- 

 sult was satisfactory, after tightening them sufhriently, 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 liqjiid gum. and committing themselves to these bridges of Uieir own constructing, they 

 (183) 



