MOTIONS OF INSECTS. 289 



over the welfare of the most insignificant of its creatures, 

 has gifted them with the means of attaining these ends, 

 without all this labour and los^ 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 which they were sta- 

 tioned ; and however sudden your attack, they are 

 nevertheless 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 

 them, 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 find it 

 again ; but thus, whenever the caterpillar falls or would 

 descend from a leaf, it has a cord always ready to sup- 

 port it in the air, by lengthening which it can with ease 

 reach the ground. Thus it can drop itself without 

 danger from the summit of the most lofty trees, and 

 ascend again by the same road. As the silky matter 

 is fluid when it issues from the spinners, it should seem 

 as if the weight of the insect would be too great, and its 

 descent too rapid, so as to cause it to fall with violence 

 upon the earth. The little animal knows how to prevent 



VOL. II. U 



