500 



MOTIONS OF INSECTS. 



their young or half-grown state^ ; whence we may infer lliat when full- 

 grown their bodies are too heavy to be thus conveyed. One spider lie 

 noticed that at one tintie contented itself with ejaculating a single thread, 

 while at others it darted out several, like so many shining rays at the 

 tail of a comet. Of these, in Cambridgeshire in October, he once saw 

 an incredible number sailing in the air.^ Speaking of his Ar. suhfus- 

 cus miniitissimis ocnlis, he, he says, " Certainly this is an excellent 

 rope-dancer, and is wonderfully delighted with darling its threads : nor 

 is it only carried in the air, like the preceding ones ; but it effects itself 

 its ascent and sailing : for, by means of its legs closely applied to each 

 other, it as it were balances itself, and promotes and directs its course 

 no otherwise than as if nature had furnished it with wings or oars."'' 

 A later but equally gifted observer of nature, Mr. White, confirms Dr. 

 Lister's account. " Every day in fine weather in autumn," says he, "do 

 I see these spiders shooting out their webs, and mounting aloft : they will 

 go off from the finger, if you lake them into your hand. Last summer 

 one aliglited on my book as I was reading in the parlor ; and running to 

 the top of the page and shooting out a web, took its departure from thence. 

 But what I most wondered at was, that it went oft' with considerable 

 velocity in a place where no air was stirring ; and I am sure that I did not 

 assist it with my breath. So that these little crawlers seem to have while 

 mounting some locomotive power without the use of wings, and, move 

 faster than the air in the air itself."^ A writer in the last number of 

 Thomson's Annals of Philosophy^, under the signature of Carolan, has 

 given some curious observations on the mode in which some geometric 

 spiders shoot and direct their threads, and fly upon them ; by which it 

 appears that as they dart them out tliey guide them as if by magic, emitting 

 at the same time a stream of air, as he supposes, or possibly some subtile 

 electric fluid. One, which was running upon his hand, dropped by its 

 thread about six inches from the point of his finger, when it immediately 

 emitted a pretty long line at a right angle with that by which it was sus- 

 pended. This thread, though at first horizontal, quickly rose upwards, 

 carrying the spider along with it. When it had ascended as far above his 

 finger as it had dropped before below it, it let out the thread by which it 

 had been attached to it, and continued flying smoothly upwards till it 

 nearly reached the roof of the room, when it veered on one side and 

 alighted on the wall. In flying, its motion was smoother and quicker than 

 when a spider runs along its thread. He observes, that as the line length- 

 ens behind them, the tendency of spiders to rise increases. I have myself 

 more than once observed these creatures take their flight, and find the fol- 

 lowing memorandum with respect to their mode of proceeding: — '-The 

 spider first extends its thighs, shanks, and feet into a right line, and then 

 elevating its abdomen till it becomes vertical, shoots its thread into the air, 

 and flies ofT from its station." It is not often, however, that an observer 

 can be gratified with this interesting sight, since these animals are soon 

 alarmed. I have frequently noticed them — for at the times when these 

 webs are floating in the air they are very numerous — on the vertical angle 

 of a post or pale, or one of the uprights of a gate, with the end of their 



> De Araneis, 8. 27. 64. 75. 79. » Ibid. 79. ' Ibid. 85. 



* Nat. Jlist. i. 327. » No. lii. 306. 



