292 MOTIONS OF INSECTS/ ' 



fluid, which hardens in the air ; so that it has no diffi- 

 culty in making it stick to the glass. — Many caterpil- 

 lars that feed upon trees, particularly the geometers, 

 have often occasion to descend from branch to branch, 

 and sometimes, especially previously to assuming the 

 pupa, to the ground. Had they to descend by the 

 trunk, supposing- them able to traverse with ease its 

 rugged bark, what a circuitous route must they take 

 before they could accomplish their purpose ! Provi- 

 dence, ever watchful over the welfare of the most in- 

 significant of its creatures, has gifted them with the 

 means of attaining these ends, without all this labour 

 and loss of time. From their own internal stores they, 

 can let down a rope, and prolong it indefinitely, which 

 will enable them to travel where they please. Shake 

 the branches of an oak or other tree in summer, and 

 its inhabitants of this description, whether they were 

 reposing, moving, or feeding, will immediately cast 

 themselves from the leaves on wliich they were sta- 

 tioned ; and however sudden your attack, they are ne- 

 vertheless still provided for it, and will all descend by 

 means of the silken cord just alluded to, and hang sus- 

 pended in the air. Their name of geometer was given 

 Ihem, because they seem to measure the surface they 

 pass over, as they walk, with a chain. If you place one 

 upon your hand, you will find that they draw a thread 

 as they go ; when they move, their head is extended 

 as far as they can reach with it : then fastening their 

 thread there, and bringing up the rest of their body, 

 they take another step ; never moving without leaving 

 this clue behind them ; the object of which, however, 

 is neither to measure, nor to mark its path that it may 



