IN THE PITTSIOLOOT OF SriDERS AND INSECTS. 155 



purpose of moving these processes ; their action must be to draw 

 the spinnerets inwards." Such is the evidence supplied by dissec- 

 tion in support of the opinion that spiders can forcibly eject their 

 lines to a distance. 



Now it is manifest from well-known physiological facts that the 

 muscles distributed to the spinning-organs perform various func- 

 tions, the office of some being to give motion to those parts, of 

 others to close either the minute aperture in the dilated base of 

 the tubular papillae, or that of the fine ducts which terminate the 

 vessels that secrete the fluid employed by spiders in the process 

 of spinning, as its issue from the papillae can be instantaneously 

 prevented at the will of the animals ; others, moreover, must pos- 

 sess a contractile force sufficient to propel the fluid to the open 

 extremity of the delicate hair-like papillae, exactly as the non- 

 viscid fluid, propelled by the contraction of the muscles connected 

 with the vessel that secretes it, passes out of, but is not ejected 

 in a stream from, the minute orifice situated near the extremity 

 of the fang that terminates the falces. 



To this extent I am prepared to admit the influence of the 

 muscles that contribute directly or indirectly to the action of the 

 spinning apparatus ; but that a remarkably viscid fluid, which 

 immediately becomes concrete on exposure to the air when drawn 

 out in a filament of such marvellous tenuity as the lines produced 

 by spiders, can, notwithstanding its extreme levity and flexibility, 

 and quite irrespective of the size of the animals producing it, be 

 propelled by any physical power vdth which they are endowed in 

 a straight line of many feet in length, through a resisting me- 

 dium liable to rapid fluctuations like the atmosphere, does appear 

 to be in the highest degree improbable, and is, as already asserted, 

 directly at variance with the result of an extensive and elaborate 

 experimental investigation of the subject*, a brief abstract of 

 which I proceed to give. 



Spiders, if placed on wooden or metallic rods set upright in 

 glass vessels with perpendicular sides, containing a sufficient quan- 

 tity of clean water completely to immerse their bases, in vain 

 attempt to effect an escape from them in a still atmosphere ; all 

 their efforts to accomplish the desired object, though perseveringly 

 persisted in, proving quite unavailing when they are placed under 

 a glass-shade, or in any situation where the air is not liable to be 



* Transactions of the Linnean Society, vol. xv. p. 455 ; Researches in 

 Zoology, pp. 242-248 ; A History of the Spiders of Great Britain and Ireland, 

 part 1st, p. 12. 



