SPIDEKS AND MITES. 247 



planation was first suggested, I believe, by Mr. Ken- 

 nie,* but it has been amplified with much force by 

 Professor Jones, in the following words : — 



" A very obvious reflection will here naturally sug- 

 gest itself, in connexion with this beautiful machinery ; 

 why, in the case of the Spider, it has been found ne- 

 cessary to provide a rope of such complex structure, 

 when in so many Insects a simple, undivided thread, 

 drawn from the orifice of a single tube, like the thread 

 of the Silkworm, for instance, was sufficient for all re- 

 quired purposes. And here, as in every other case, it 

 will be found, on consideration, that a complicated ap- 

 paratus has been substituted for a simple one only to 

 meet the requirements of strict necessity. The slow- 

 moving Caterpillar, as it leisurely produces its silken 

 cord, gives time enough for the fluid of which it is 

 formed to harden by degrees into a tenacious filament, 

 as it is allowed to issue by instalments from the end of 

 the labial pipe ; but the habits of the Spider require a 

 different mode of proceeding, as its line must be in- 

 stantly converted from a fluid into a strong rope, or it 

 would be of no use for the purposes it is intended to 

 fulfil. Let a fly, for example, become entangled in the 

 meshes of a Spider's web ; no time is to be lost ; the 

 strugghng victim, by every effort to escape, is tearing 

 the meshes that entangle it, and would soon succeed 

 in breaking loose did not its lurking destroyer at once 

 rush out to complete the capture and save its net, spun 

 with so much labour, from ruin. With the rapidity of 

 thought, it darts upon its prey ; and before the eye of 

 the spectator can comprehend the manceuvre, the poor 

 fly is swathed in silken bands, imtil it is as incapable 

 * Insect Architecture, 337. 



